Results for "Bronchioles"

System Interactions in Animals Tools Finish System Interactions in Animals The human body is made of many different organ systems. Each system performs unique functions for the body, but the systems also interact with each other to perform more complex functions. Major Organ Systems Body Systems In humans, cells, tissues, and organs group together to form organ systems. These systems each perform different functions for the human body. The major organ systems and their functions in humans include: The Nervous System — The nervous systems consists of two parts. The central nervous system consists of the brain and spinal cord, while the peripheral nervous system consists of nerves that connect the central nervous system to other parts of the body. The brain plays an important role in interpreting the information picked up by the sensory system. It helps in producing a precise response to the stimuli. It also controls bodily functions such as movements, thoughts, speech, and memory. The brain also controls many processes related to homeostasis in the body. The spinal cord connects to the brain through the brainstem. From the brainstem, the spinal cord extends to all the major nerves in the body. The spinal cord is the origin of spinal nerves that branch out to various body parts. These nerves help in receiving and transmitting signals from various body parts. The spinal cord helps in reflex actions of the body The smallest unit of the nervous system is the nerve cell, or neuron. Neurons communicate with each other and with other cells by producing and releasing electrochemical signals known as nerve impulses. Neurons consist of the cell body, the dendrites, and the axon. The cell body consists of a nucleus and cytoplasm. Dendrites are specialized branch-like structures that help in conducting impulses to and from the various body parts. Axons are long, slender extensions of the neuron. Each neuron possesses just a single axon. Its function is to carry the impulses away from the cell body to other neurons. The Circulatory System — The circulatory (or cardiovascular) system is composed of the heart, arteries, veins, and capillaries. The circulatory system is responsible for transporting blood to and from the lungs so that gas exchange can take place. As the circulatory system pumps blood throughout the body, dissolved nutrients and wastes are also delivered to their destinations. The heart is a muscular organ roughly the size of an adult human's closed fist. It is present behind the breastbone, slightly to the left. It consists of four chambers: right atrium, left atrium, right ventricle, and left ventricle. The heart receives deoxygenated blood from the body and pumps this blood to the lugs, where it is oxygenated. The oxygen-rich blood reenters the heart and is then pumped back through the body. The circulatory system is responsible for transporting blood to and from the lungs so that gas exchange can take place. As the circulatory system pumps blood throughout the body, dissolved nutrients and wastes are also delivered to their destinations. Blood circulation takes place through blood vessels. Blood vessels are tubular structures that form a network within the body and transport blood to each tissue. There are three major types of blood vessels: veins, arteries, and capillaries. Veins carry deoxygenated blood from the body to the heart, except for pulmonary veins, which carry oxygenated blood from the lungs to the heart. Arteries carry oxygenated blood from the heart to different organs, except for the pulmonary artery, which carries deoxygenated blood from the heart to the lungs. The arteries branch out to form capillaries. These capillaries are thin-walled vessels through which nutrients and wastes are exchanged with cells. The Respiratory System — The main structures of the respiratory system are the trachea (windpipe), the lungs, and the diaphragm. When the diaphragm contracts, it creates a vacuum in the lungs that causes them to fill with air. During this inhalation, oxygen diffuses into the circulatory system while carbon dioxide diffuses out into the air that will be exhaled. The trachea branches out into two primary bronchi. Each bronchus is further divided into numerous secondary bronchi. These secondary bronchi further branch into tertiary bronchi. Finally, each tertiary bronchus branches into numerous bronchioles. Each bronchiole terminates into a tiny, sac-like structure known as an alveolus. The walls of each alveolus are thin and contain numerous blood capillaries. The process of gaseous exchange occurs in these alveoli. The diaphragm is a dome-shaped muscle situated at the lower end of the rib cage. It separates the abdominal cavity from the chest cavity. During inhalation, the diaphragm contracts, and the chest cavity enlarges, creating a vacuum that allows air to be drawn in. This causes the alveoli in the lungs to expand with air. During this process, oxygen diffuses into the circulatory system while carbon dioxide diffuses out into the air that will be exhaled. On the other hand, expansion of the diaphragm causes exhalation of air containing carbon dioxide. The Digestive System — The digestive system consists of the mouth, stomach, small intestine, large intestine, and anus. It is responsible for taking in food, digesting it to extract energy and nutrients that cells can use to function, and expelling the remaining waste material. Mechanical and chemical digestion takes place in the mouth and stomach, while absorption of nutrients and water takes place in the intestines. The digestive system begins at the mouth, where food is taken in, and ends at the anus, where waste is expelled. The food taken into the mouth breaks into pieces by the grinding action of the teeth. Carbohydrate digestion starts in the mouth with the breakdown of carbohydrates into simple sugars with the help of salivary enzymes. The chewed food, known as a bolus, enters the stomach through the esophagus. The bolus mixes with acids and enzymes released by the stomach. Protein digestion starts in the stomach as proteins are broken down into peptides. This partially digested food is known as chyme. Chyme enters the small intestine and mixes with bile, a substance secreted by the liver, along with enzymes secreted by the pancreas. The digestion of fats starts in the small intestine as bile and pancreatic enzymes break down fats into fatty acids. The surface of the small intestine consists of hair-like projections known as villi. These villi help in absorbing nutrients from the digested food. The digested food enters the large intestine, or colon, where water and salts are reabsorbed. Any undigested food is expelled out of the body as waste. The Skeletal System — The skeletal system is made up of over 200 bones. It protects the body's internal organs, provides support for the body and gives it shape, and works with the muscular system to move the body. In addition, bones can store calcium and produce red and white blood cells. The Muscular System — The muscular system includes more than 650 tough, elastic pieces of tissue. The primary function of any muscle tissue is movement. This includes the movement of blood through the arteries, the movement of food through the digestive tract, and the movement of arms and legs through space. Skeletal muscles relax and contract to move the bones of the skeletal system. The Excretory System — The excretory system removes excess water, dangerous substances, and wastes from the body. The excretory system also plays an important role in maintaining body equilibrium, or homeostasis. The human excretory system includes the lungs, sweat glands in the skin, and the urinary system (such as the kidneys and the bladder). The body uses oxygen for metabolic processes. Oxygen metabolism results in the production of carbon dioxide, which is a waste matter. The lungs expel carbon dioxide through the mouth and nose. The liver converts toxic metabolic wastes, such as ammonia, into less harmful susbtances. Ammonia is converted to urea, which is then excreted in the urine. The skin also expels urea and small amounts of ammonia through sweat. The skin is embedded with sweat glands. These glands secrete sweat, a solution of water, salt, and wastes. The sweat rises to the skin's surface, where it evaporates. The skin maintains homeostasis by producing sweat in hot environments. Sweat production cools and prevents excessive heating of the body. Each kidney contains about a million tiny structures called nephrons, which filter the blood and collect waste products, such as urea, salts, and excess water that go on to become urine. The Endocrine System — The endocrine system is involved with the control of body processes such as fluid balance, growth, and sexual development. The endocrine system controls these processes through hormones, which are produced by endocrine glands. Some endocrine glands include the pituitary gland, thyroid gland, parathyroid gland, adrenal glands, thymus gland, ovaries in females, and testes in males. The Immune System — The immune system is a network of cells, tissues, and organs that defends the body against foreign invaders. The immune system uses antibodies and specialized cells, such as T-cells, to defend the body from microorganisms that cause disease. The Reproductive System — The reproductive system includes structures, such as the uterus and fallopian tubes in females and the penis and testes in males, that allow humans to produce new offspring. The reproductive system also controls certain hormones in the human body that regulate the development of sexual characteristics and determine when the body is able to reproduce. The Integumentary System — The integumentary system is made up of a person's skin, hair, and nails. The skin acts as a barrier to the outside world by keeping moisture in the body and foreign substances out of the body. Nerves in the skin act as an interface with the outside world, helping to regulate important aspects of homeostasis, such as body temperature. Interacting Organ Systems The organ systems work together to perform complex bodily functions. The functions of regulation, nutrient absorption, defense, and reproduction are only possible because of the interaction of multiple body systems. Regulation All living organisms must maintain homeostasis, a stable internal environment. Organisms maintain homeostasis by monitoring internal conditions and making adjustments to the body systems as necessary. For example, as body temperature increases, skin receptors and receptors in a region of the brain called the hypothalamus sense the change. The change triggers the nervous system to send signals to the integumentary and circulatory systems. These signals cause the skin to sweat and blood vessels close to the surface of the skin to dilate, actions which dispel heat to decrease body temperature. Both the nervous system and the endocrine system are typically involved in the maintenance of homeostasis. The nervous system receives and processes stimuli, and then it sends signals to body structures to coordinate a response. The endocrine system helps regulate the response through the release of hormones, which travel through the circulatory system to their site of action. For example, the endocrine system regulates the level of sugar in the blood by the release of the hormones insulin, which stimulates uptake of glucose by cells, and glucagon, which stimulates the release of glucose by the liver. The nervous and endocrine systems interact with the excretory system in the process of osmoregulation, the homeostatic regulation of water and fluid balance in the body. The excretory system expels excess water, salts, and waste products. The excretion of excessive amounts of water can be harmful to the body because it reduces blood pressure. If the nervous system detects a decrease in blood pressure, it stimulates the endocrine system to release antidiuretic hormone. This hormone decreases the amount of water released by the kidneys to ensure appropriate blood pressure. Appropriate levels of carbon dioxide in the blood are also maintained by homeostatic mechanisms that involve several organ systems. Excess carbon dioxide, a byproduct of cellular respiration, can be harmful to an organism. As blood circulates throughout the body, it picks up carbon dioxide waste from cells and transports it to the lungs, where it is exhaled while fresh oxygen is inhaled. If the concentration of carbon dioxide in the blood increases above a certain threshold, the nervous system directs the lungs to increase their respiration rate to remove the excess carbon dioxide, which ensures that the levels of carbon dioxide in the blood are maintained at appropriate levels. In this way, the circulatory, respiratory, and nervous systems work together to limit the level of carbon dioxide in the blood. Nutrient Absorption To absorb nutrients from food, the nervous, digestive, muscular, excretory, and circulatory systems all interact. The nervous system controls the intake of food and regulates the muscular action of chewing, which mechanically breaks down food. As food travels through the stomach and intestines, the digestive system structures release enzymes to stimulate its chemical breakdown. At the same time, the muscular action, called peristalsis, of the muscles in the wall of the stomach help churn the food and push it through the digestive tract. In the intestines, nutrients from food travel across the surfaces of the villi. The nutrients are then picked up by the blood, and the circulatory system transports the nutrients throughout the cells of the body. The endocrine system releases hormones, such as insulin, that control the rate at which certain body cells use nutrients. Any excess minerals, such as calcium, in the blood are deposited in and stored by the skeletal system. Waste products produced by the use of nutrients, as well as the leftover solid waste from the digestion of food, exit the body through the excretory system. Throughout the process of nutrient absorption, the nervous system controls the muscles involved in digestion, circulation, and excretion. Defense Several body systems interact to defend the body from external threats. The body's first line of defense is the integumentary system, which provide a physical barrier that prevents pathogens from entering the body. The skin of the integumentary system also contains receptors for pain, temperature, and pressure. If an unpleasant stimulus is encountered, these receptors send signals to the central nervous system. In response, the central nervous system sends commands to the muscles to move the body part away from the stimulus. In this way, the integumentary, nervous, and muscular systems interact to prevent damage to the body. In the event of a break in the skin, the nervous, immune, lymphatic, and circulatory systems work together to repair the wound and protect the body from pathogens. When the skin is broken, specialized blood cells called platelets form a clot to stop the bleeding. These platelets also release chemicals that travel through the circulatory system and recruit cells, like immune system cells, to repair the wound. These immune cells, or white blood cells, are transported by the circulatory and lymphatic systems to the site of the wound, where they identify and destroy potentially pathogenic cells to prevent an infection. Some lymphocytes, white blood cells produced by the lymphatic system, also produce antibodies to neutralize specific pathogens. All of the white blood cells involved in the body's response were originally produced in the bone marrow of the skeletal system. If an infection does occur

Bronchioles and alveoli

Endocrine System 1. What are hormones and what is their function in the body? Hormones are chemical messengers transported in the bloodstream that stimulate physiological responses in target cells or organs. 2. Types of hormones Endocrine System 1. What are hormones and what is their function in the body? Hormones are chemical messengers transported in the bloodstream that stimulate physiological responses in target cells or organs. 2. Types of hormones based on chemical composition and how they enter target cells: • Steroid hormones: Lipid-soluble, diffuse through cell membrane (e.g., cortisol). • Protein/Peptide hormones: Water-soluble, bind to surface receptors (e.g., insulin). • Biogenic/Monoamines: Derived from amino acids (e.g., T3/T4), may need carriers or membrane receptors. 3. Know all 6 hormones secreted by the anterior pituitary gland and their functions: • TSH: Stimulates thyroid to release T3 and T4. • ACTH: Stimulates adrenal cortex to release cortisol. • GH: Stimulates tissue growth and protein synthesis. • PRL: Stimulates milk production. • FSH: Stimulates egg maturation/sperm production. • LH: Triggers ovulation and testosterone production. 4. What is thymosin? Which gland secretes it? What is its function? Thymosin is secreted by the thymus and helps in the development and maturation of T-cells. 5. Know thyroid gland hormones, the cells that secrete them, and their functions: • T3 & T4 (follicular cells): Increase metabolism and regulate appetite. • Calcitonin (C cells): Lowers blood calcium levels. 6. Know the hormones secreted by the adrenal gland and their specific functions: • Cortex: • Aldosterone: Retains Na⁺, excretes K⁺, raises blood pressure. • Cortisol: Increases glucose, metabolism of fat/protein. • Androgens: Precursor to sex hormones. • Medulla: • Epinephrine/Norepinephrine: Increase heart rate, blood flow, and alertness. 7. Function of glucagon and insulin in maintaining homeostasis: • Insulin (beta cells): Lowers blood glucose. • Glucagon (alpha cells): Raises blood glucose. • Antagonistic: They have opposing effects to balance blood sugar levels. 8. Which cells are involved in spermatogenesis? Where does sperm production occur? • Sertoli (Sustentacular) cells support spermatogenesis. • Leydig (Interstitial) cells produce testosterone. • Occurs in the seminiferous tubules of the testes. 9. Know the hormones secreted by the testes and their functions: • Testosterone: Stimulates male development and sperm production. • Inhibin: Inhibits FSH to regulate sperm production. 10. What causes diabetes insipidus? How is it different from diabetes mellitus? • Diabetes insipidus: ADH deficiency → excessive urination. • Diabetes mellitus: Insulin issues → high blood glucose. 11. Know the 3 “P’s” of diabetes: • Polyuria: Excessive urination. • Polydipsia: Excessive thirst. • Polyphagia: Excessive hunger. 12. How are oxytocin and prolactin different? • Oxytocin: Stimulates uterine contractions and milk letdown. • Prolactin: Stimulates milk production. 13. Name the ovarian hormones and their functions: • Estrogen/Progesterone: Regulate cycle, pregnancy, and secondary sex characteristics. • Inhibin: Inhibits FSH secretion. ⸻ Muscle Physiology 14. Know 3 muscle types, their locations, and function: • Skeletal: Attached to bones; movement; voluntary. • Cardiac: Heart; pumps blood; involuntary. • Smooth: Organs/vessels; propels substances; involuntary. 15. Know the layers surrounding muscle: • Epimysium: Surrounds entire muscle. • Perimysium: Surrounds fascicle (bundle). • Endomysium: Surrounds individual fiber. 16. What is a fascicle? A bundle of muscle fibers. 17. What is a sarcomere? Name its regions: Smallest contractile unit (Z-disc to Z-disc). • Z-band, A-band (dark), I-band (light), H-zone. 18. What are actin and myosin? • Actin: Thin filament. • Myosin: Thick filament that pulls actin during contraction. 19. What is troponin and tropomyosin? • Tropomyosin blocks binding sites on actin. • Troponin binds Ca²⁺ to move tropomyosin and expose sites. 20. What is a motor unit? A motor neuron and all muscle fibers it controls. 21. Role of T-Tubule, SR, Terminal Cisternae: • T-Tubule: Conducts AP into cell. • SR: Stores calcium. • Terminal cisternae: Release calcium. 22. Which neurotransmitter is released at the neuromuscular junction? Acetylcholine (ACh). 23. What role does Ca²⁺ play in muscle physiology? Binds troponin, moves tropomyosin, exposes actin sites. 24. What happens to Ca²⁺ after action potential ends? Reabsorbed into SR by Ca²⁺ ATPase pump. 25. What is the function of ATP in muscle physiology? Powers myosin movement, detachment, and Ca²⁺ reuptake. 26. What is sliding filament theory? Myosin pulls actin filaments → sarcomere shortens → contraction. 27. What are DHP and Ryanodine receptors and their roles? • DHP: Voltage sensor in T-tubule. • Ryanodine: Releases Ca²⁺ from SR. 28. What is the function of AChE? Breaks down ACh to stop stimulation and contraction. 29. Difference between isotonic and isometric contractions: • Isotonic: Muscle changes length (shortens/lengthens). • Isometric: Muscle length stays same; tension builds. ⸻ Respiratory Physiology 30. Difference between conductive and respiratory divisions: • Conductive: Air passageways (nose to bronchioles). • Respiratory: Gas exchange (alveoli). 31. Type I & II alveolar cells and functions: • Type I: Gas exchange. • Type II: Secretes surfactant, repairs alveoli. 32. Dust cells and their functions: Alveolar macrophages that clean up particles/debris. 33. Muscles in relaxed vs. forced respiration: • Relaxed inhale: Diaphragm, external intercostals. • Forced inhale: Accessory neck muscles. • Forced exhale: Internal intercostals, abdominals. 34. What happens to pressure and volume when inhaling/exhaling? • Inhale: Volume ↑, pressure ↓. • Exhale: Volume ↓, pressure ↑. 35. Difference between systemic and pulmonary exchange: • Systemic: Gas exchange at tissues. • Pulmonary: Gas exchange in lungs. 36. What cells are involved in carrying gases? Red blood cells (RBCs). 37. Which enzyme converts CO₂ + H₂O → H₂CO₃? Carbonic anhydrase. 38. What does carbonic acid break into? H⁺ + HCO₃⁻ (bicarbonate ion). 39. What happens in hypoxia (low oxygen)? • ↓O₂, ↑CO₂, ↓pH (acidosis). 40. What happens in hypercapnia (high CO₂)? • ↑CO₂, ↓O₂, ↓pH (acidosis). 41. Receptors for blood pH and their locations: • Central (CSF pH): Medulla oblongata. • Peripheral (O₂, CO₂, pH): Carotid & aortic bodies. 42. CO₂ loading & O₂ unloading at tissues: • CO₂ enters blood → forms HCO₃⁻. • O₂ released to tissues. 43. CO₂ unloading & O₂ loading at alveoli: • CO₂ released from blood to lungs. • O₂ binds to hemoglobin. 44. Brain part for unconscious breathing: Medulla oblongata. 45. Obstructive vs. restrictive disorders + example: • Obstructive: Narrowed airways (asthma). • Restrictive: Reduced lung expansion (fibrosis). 46. Know spirometry volumes (not numbers): • Tidal volume, • Inspiratory/Expiratory reserve volume, • Residual volume, • Vital capacity, • Total lung capacity, • Inspiratory capacity, • Functional residual capacity. 47. Define eupnea, dyspnea, tachypnea, apnea, Kussmaul respiration: • Eupnea: Normal breathing. • Dyspnea: Labored breathing. • Tachypnea: Rapid, shallow breathing. • Apnea: No breathing. • Kussmaul: Deep, rapid (from acidosis Endocrine System 1. What are hormones and what is their function in the body? Hormones are chemical messengers transported in the bloodstream that stimulate physiological responses in target cells or organs. 2. Types of hormones based on chemical composition and how they enter target cells: • Steroid hormones: Lipid-soluble, diffuse through cell membrane (e.g., cortisol). • Protein/Peptide hormones: Water-soluble, bind to surface receptors (e.g., insulin). • Biogenic/Monoamines: Derived from amino acids (e.g., T3/T4), may need carriers or membrane receptors. 3. Know all 6 hormones secreted by the anterior pituitary gland and their functions: • TSH: Stimulates thyroid to release T3 and T4. • ACTH: Stimulates adrenal cortex to release cortisol. • GH: Stimulates tissue growth and protein synthesis. • PRL: Stimulates milk production. • FSH: Stimulates egg maturation/sperm production. • LH: Triggers ovulation and testosterone production. 4. What is thymosin? Which gland secretes it? What is its function? Thymosin is secreted by the thymus and helps in the development and maturation of T-cells. 5. Know thyroid gland hormones, the cells that secrete them, and their functions: • T3 & T4 (follicular cells): Increase metabolism and regulate appetite. • Calcitonin (C cells): Lowers blood calcium levels. 6. Know the hormones secreted by the adrenal gland and their specific functions: • Cortex: • Aldosterone: Retains Na⁺, excretes K⁺, raises blood pressure. • Cortisol: Increases glucose, metabolism of fat/protein. • Androgens: Precursor to sex hormones. • Medulla: • Epinephrine/Norepinephrine: Increase heart rate, blood flow, and alertness. 7. Function of glucagon and insulin in maintaining homeostasis: • Insulin (beta cells): Lowers blood glucose. • Glucagon (alpha cells): Raises blood glucose. • Antagonistic: They have opposing effects to balance blood sugar levels. 8. Which cells are involved in spermatogenesis? Where does sperm production occur? • Sertoli (Sustentacular) cells support spermatogenesis. • Leydig (Interstitial) cells produce testosterone. • Occurs in the seminiferous tubules of the testes. 9. Know the hormones secreted by the testes and their functions: • Testosterone: Stimulates male development and sperm production. • Inhibin: Inhibits FSH to regulate sperm production. 10. What causes diabetes insipidus? How is it different from diabetes mellitus? • Diabetes insipidus: ADH deficiency → excessive urination. • Diabetes mellitus: Insulin issues → high blood glucose. 11. Know the 3 “P’s” of diabetes: • Polyuria: Excessive urination. • Polydipsia: Excessive thirst. • Polyphagia: Excessive hunger. 12. How are oxytocin and prolactin different? • Oxytocin: Stimulates uterine contractions and milk letdown. • Prolactin: Stimulates milk production. 13. Name the ovarian hormones and their functions: • Estrogen/Progesterone: Regulate cycle, pregnancy, and secondary sex characteristics. • Inhibin: Inhibits FSH secretion. ⸻ Muscle Physiology 14. Know 3 muscle types, their locations, and function: • Skeletal: Attached to bones; movement; voluntary. • Cardiac: Heart; pumps blood; involuntary. • Smooth: Organs/vessels; propels substances; involuntary. 15. Know the layers surrounding muscle: • Epimysium: Surrounds entire muscle. • Perimysium: Surrounds fascicle (bundle). • Endomysium: Surrounds individual fiber. 16. What is a fascicle? A bundle of muscle fibers. 17. What is a sarcomere? Name its regions: Smallest contractile unit (Z-disc to Z-disc). • Z-band, A-band (dark), I-band (light), H-zone. 18. What are actin and myosin? • Actin: Thin filament. • Myosin: Thick filament that pulls actin during contraction. 19. What is troponin and tropomyosin? • Tropomyosin blocks binding sites on actin. • Troponin binds Ca²⁺ to move tropomyosin and expose sites. 20. What is a motor unit? A motor neuron and all muscle fibers it controls. 21. Role of T-Tubule, SR, Terminal Cisternae: • T-Tubule: Conducts AP into cell. • SR: Stores calcium. • Terminal cisternae: Release calcium. 22. Which neurotransmitter is released at the neuromuscular junction? Acetylcholine (ACh). 23. What role does Ca²⁺ play in muscle physiology? Binds troponin, moves tropomyosin, exposes actin sites. 24. What happens to Ca²⁺ after action potential ends? Reabsorbed into SR by Ca²⁺ ATPase pump. 25. What is the function of ATP in muscle physiology? Powers myosin movement, detachment, and Ca²⁺ reuptake. 26. What is sliding filament theory? Myosin pulls actin filaments → sarcomere shortens → contraction. 27. What are DHP and Ryanodine receptors and their roles? • DHP: Voltage sensor in T-tubule. • Ryanodine: Releases Ca²⁺ from SR. 28. What is the function of AChE? Breaks down ACh to stop stimulation and contraction. 29. Difference between isotonic and isometric contractions: • Isotonic: Muscle changes length (shortens/lengthens). • Isometric: Muscle length stays same; tension builds. ⸻ Respiratory Physiology 30. Difference between conductive and respiratory divisions: • Conductive: Air passageways (nose to bronchioles). • Respiratory: Gas exchange (alveoli). 31. Type I & II alveolar cells and functions: • Type I: Gas exchange. • Type II: Secretes surfactant, repairs alveoli. 32. Dust cells and their functions: Alveolar macrophages that clean up particles/debris. 33. Muscles in relaxed vs. forced respiration: • Relaxed inhale: Diaphragm, external intercostals. • Forced inhale: Accessory neck muscles. • Forced exhale: Internal intercostals, abdominals. 34. What happens to pressure and volume when inhaling/exhaling? • Inhale: Volume ↑, pressure ↓. • Exhale: Volume ↓, pressure ↑. 35. Difference between systemic and pulmonary exchange: • Systemic: Gas exchange at tissues. • Pulmonary: Gas exchange in lungs. 36. What cells are involved in carrying gases? Red blood cells (RBCs). 37. Which enzyme converts CO₂ + H₂O → H₂CO₃? Carbonic anhydrase. 38. What does carbonic acid break into? H⁺ + HCO₃⁻ (bicarbonate ion). 39. What happens in hypoxia (low oxygen)? • ↓O₂, ↑CO₂, ↓pH (acidosis). 40. What happens in hypercapnia (high CO₂)? • ↑CO₂, ↓O₂, ↓pH (acidosis). 41. Receptors for blood pH and their locations: • Central (CSF pH): Medulla oblongata. • Peripheral (O₂, CO₂, pH): Carotid & aortic bodies. 42. CO₂ loading & O₂ unloading at tissues: • CO₂ enters blood → forms HCO₃⁻. • O₂ released to tissues. 43. CO₂ unloading & O₂ loading at alveoli: • CO₂ released from blood to lungs. • O₂ binds to hemoglobin. 44. Brain part for unconscious breathing: Medulla oblongata. 45. Obstructive vs. restrictive disorders + example: • Obstructive: Narrowed airways (asthma). • Restrictive: Reduced lung expansion (fibrosis). 46. Know spirometry volumes (not numbers): • Tidal volume, • Inspiratory/Expiratory reserve volume, • Residual volume, • Vital capacity, • Total lung capacity, • Inspiratory capacity, • Functional residual capacity. 47. Define eupnea, dyspnea, tachypnea, apnea, Kussmaul respiration: • Eupnea: Normal breathing. • Dyspnea: Labored breathing. • Tachypnea: Rapid, shallow breathing. • Apnea: No breathing. • Kussmaul: Deep, rapid (from acidosis Endocrine System 1. What are hormones and what is their function in the body? Hormones are chemical messengers transported in the bloodstream that stimulate physiological responses in target cells or organs. 2. Types of hormones based on chemical composition and how they enter target cells: • Steroid hormones: Lipid-soluble, diffuse through cell membrane (e.g., cortisol). • Protein/Peptide hormones: Water-soluble, bind to surface receptors (e.g., insulin). • Biogenic/Monoamines: Derived from amino acids (e.g., T3/T4), may need carriers or membrane receptors. 3. Know all 6 hormones secreted by the anterior pituitary gland and their functions: • TSH: Stimulates thyroid to release T3 and T4. • ACTH: Stimulates adrenal cortex to release cortisol. • GH: Stimulates tissue growth and protein synthesis. • PRL: Stimulates milk production. • FSH: Stimulates egg maturation/sperm production. • LH: Triggers ovulation and testosterone production. 4. What is thymosin? Which gland secretes it? What is its function? Thymosin is secreted by the thymus and helps in the development and maturation of T-cells. 5. Know thyroid gland hormones, the cells that secrete them, and their functions: • T3 & T4 (follicular cells): Increase metabolism and regulate appetite. • Calcitonin (C cells): Lowers blood calcium levels. 6. Know the hormones secreted by the adrenal gland and their specific functions: • Cortex: • Aldosterone: Retains Na⁺, excretes K⁺, raises blood pressure. • Cortisol: Increases glucose, metabolism of fat/protein. • Androgens: Precursor to sex hormones. • Medulla: • Epinephrine/Norepinephrine: Increase heart rate, blood flow, and alertness. 7. Function of glucagon and insulin in maintaining homeostasis: • Insulin (beta cells): Lowers blood glucose. • Glucagon (alpha cells): Raises blood glucose. • Antagonistic: They have opposing effects to balance blood sugar levels. 8. Which cells are involved in spermatogenesis? Where does sperm production occur? • Sertoli (Sustentacular) cells support spermatogenesis. • Leydig (Interstitial) cells produce testosterone. • Occurs in the seminiferous tubules of the testes. 9. Know the hormones secreted by the testes and their functions: • Testosterone: Stimulates male development and sperm production. • Inhibin: Inhibits FSH to regulate sperm production. 10. What causes diabetes insipidus? How is it different from diabetes mellitus? • Diabetes insipidus: ADH deficiency → excessive urination. • Diabetes mellitus: Insulin issues → high blood glucose. 11. Know the 3 “P’s” of diabetes: • Polyuria: Excessive urination. • Polydipsia: Excessive thirst. • Polyphagia: Excessive hunger. 12. How are oxytocin and prolactin different? • Oxytocin: Stimulates uterine contractions and milk letdown. • Prolactin: Stimulates milk production. 13. Name the ovarian hormones and their functions: • Estrogen/Progesterone: Regulate cycle, pregnancy, and secondary sex characteristics. • Inhibin: Inhibits FSH secretion. ⸻ Muscle Physiology 14. Know 3 muscle types, their locations, and function: • Skeletal: Attached to bones; movement; voluntary. • Cardiac: Heart; pumps blood; involuntary. • Smooth: Organs/vessels; propels substances; involuntary. 15. Know the layers surrounding muscle: • Epimysium: Surrounds entire muscle. • Perimysium: Surrounds fascicle (bundle). • Endomysium: Surrounds individual fiber. 16. What is a fascicle? A bundle of muscle fibers. 17. What is a sarcomere? Name its regions: Smallest contractile unit (Z-disc to Z-disc). • Z-band, A-band (dark), I-band (light), H-zone. 18. What are actin and myosin? • Actin: Thin filament. • Myosin: Thick filament that pulls actin during contraction. 19. What is troponin and tropomyosin? • Tropomyosin blocks binding sites on actin. • Troponin binds Ca²⁺ to move tropomyosin and expose sites. 20. What is a motor unit? A motor neuron and all muscle fibers it controls. 21. Role of T-Tubule, SR, Terminal Cisternae: • T-Tubule: Conducts AP into cell. • SR: Stores calcium. • Terminal cisternae: Release calcium. 22. Which neurotransmitter is released at the neuromuscular junction? Acetylcholine (ACh). 23. What role does Ca²⁺ play in muscle physiology? Binds troponin, moves tropomyosin, exposes actin sites. 24. What happens to Ca²⁺ after action potential ends? Reabsorbed into SR by Ca²⁺ ATPase pump. 25. What is the function of ATP in muscle physiology? Powers myosin movement, detachment, and Ca²⁺ reuptake. 26. What is sliding filament theory? Myosin pulls actin filaments → sarcomere shortens → contraction. 27. What are DHP and Ryanodine receptors and their roles? • DHP: Voltage sensor in T-tubule. • Ryanodine: Releases Ca²⁺ from SR. 28. What is the function of AChE? Breaks down ACh to stop stimulation and contraction. 29. Difference between isotonic and isometric contractions: • Isotonic: Muscle changes length (shortens/lengthens). • Isometric: Muscle length stays same; tension builds. ⸻ Respiratory Physiology 30. Difference between conductive and respiratory divisions: • Conductive: Air passageways (nose to bronchioles). • Respiratory: Gas exchange (alveoli). 31. Type I & II alveolar cells and functions: • Type I: Gas exchange. • Type II: Secretes surfactant, repairs alveoli. 32. Dust cells and their functions: Alveolar macrophages that clean up particles/debris. 33. Muscles in relaxed vs. forced respiration: • Relaxed inhale: Diaphragm, external intercostals. • Forced inhale: Accessory neck muscles. • Forced exhale: Internal intercostals, abdominals. 34. What happens to pressure and volume when inhaling/exhaling? • Inhale: Volume ↑, pressure ↓. • Exhale: Volume ↓, pressure ↑. 35. Difference between systemic and pulmonary exchange: • Systemic: Gas exchange at tissues. • Pulmonary: Gas exchange in lungs. 36. What cells are involved in carrying gases? Red blood cells (RBCs). 37. Which enzyme converts CO₂ + H₂O → H₂CO₃? Carbonic anhydrase. 38. What does carbonic acid break into? H⁺ + HCO₃⁻ (bicarbonate ion). 39. What happens in hypoxia (low oxygen)? • ↓O₂, ↑CO₂, ↓pH (acidosis). 40. What happens in hypercapnia (high CO₂)? • ↑CO₂, ↓O₂, ↓pH (acidosis). 41. Receptors for blood pH and their locations: • Central (CSF pH): Medulla oblongata. • Peripheral (O₂, CO₂, pH): Carotid & aortic bodies. 42. CO₂ loading & O₂ unloading at tissues: • CO₂ enters blood → forms HCO₃⁻. • O₂ released to tissues. 43. CO₂ unloading & O₂ loading at alveoli: • CO₂ released from blood to lungs. • O₂ binds to hemoglobin. 44. Brain part for unconscious breathing: Medulla oblongata. 45. Obstructive vs. restrictive disorders + example: • Obstructive: Narrowed airways (asthma). • Restrictive: Reduced lung expansion (fibrosis). 46. Know spirometry volumes (not numbers): • Tidal volume, • Inspiratory/Expiratory reserve volume, • Residual volume, • Vital capacity, • Total lung capacity, • Inspiratory capacity, • Functional residual capacity. 47. Define eupnea, dyspnea, tachypnea, apnea, Kussmaul respiration: • Eupnea: Normal breathing. • Dyspnea: Labored breathing. • Tachypnea: Rapid, shallow breathing. • Apnea: No breathing. • Kussmaul: Deep, rapid (from acidosis based on chemical composition and how they enter target cells: • Steroid hormones: Lipid-soluble, diffuse through cell membrane (e.g., cortisol). • Protein/Peptide hormones: Water-soluble, bind to surface receptors (e.g., insulin). • Biogenic/Monoamines: Derived from amino acids (e.g., T3/T4), may need carriers or membrane receptors. 3. Know all 6 hormones secreted by the anterior pituitary gland and their functions: • TSH: Stimulates thyroid to release T3 and T4. • ACTH: Stimulates adrenal cortex to release cortisol. • GH: Stimulates tissue growth and protein synthesis. • PRL: Stimulates milk production. • FSH: Stimulates egg maturation/sperm production. • LH: Triggers ovulation and testosterone production. 4. What is thymosin? Which gland secretes it? What is its function? Thymosin is secreted by the thymus and helps in the development and maturation of T-cells. 5. Know thyroid gland hormones, the cells that secrete them, and their functions: • T3 & T4 (follicular cells): Increase metabolism and regulate appetite. • Calcitonin (C cells): Lowers blood calcium levels. 6. Know the hormones secreted by the adrenal gland and their specific functions: • Cortex: • Aldosterone: Retains Na⁺, excretes K⁺, raises blood pressure. • Cortisol: Increases glucose, metabolism of fat/protein. • Androgens: Precursor to sex hormones. • Medulla: • Epinephrine/Norepinephrine: Increase heart rate, blood flow, and alertness. 7. Function of glucagon and insulin in maintaining homeostasis: • Insulin (beta cells): Lowers blood glucose. • Glucagon (alpha cells): Raises blood glucose. • Antagonistic: They have opposing effects to balance blood sugar levels. 8. Which cells are involved in spermatogenesis? Where does sperm production occur? • Sertoli (Sustentacular) cells support spermatogenesis. • Leydig (Interstitial) cells produce testosterone. • Occurs in the seminiferous tubules of the testes. 9. Know the hormones secreted by the testes and their functions: • Testosterone: Stimulates male development and sperm production. • Inhibin: Inhibits FSH to regulate sperm production. 10. What causes diabetes insipidus? How is it different from diabetes mellitus? • Diabetes insipidus: ADH deficiency → excessive urination. • Diabetes mellitus: Insulin issues → high blood glucose. 11. Know the 3 “P’s” of diabetes: • Polyuria: Excessive urination. • Polydipsia: Excessive thirst. • Polyphagia: Excessive hunger. 12. How are oxytocin and prolactin different? • Oxytocin: Stimulates uterine contractions and milk letdown. • Prolactin: Stimulates milk production. 13. Name the ovarian hormones and their functions: • Estrogen/Progesterone: Regulate cycle, pregnancy, and secondary sex characteristics. • Inhibin: Inhibits FSH secretion. ⸻ Muscle Physiology 14. Know 3 muscle types, their locations, and function: • Skeletal: Attached to bones; movement; voluntary. • Cardiac: Heart; pumps blood; involuntary. • Smooth: Organs/vessels; propels substances; involuntary. 15. Know the layers surrounding muscle: • Epimysium: Surrounds entire muscle. • Perimysium: Surrounds fascicle (bundle). • Endomysium: Surrounds individual fiber. 16. What is a fascicle? A bundle of muscle fibers. 17. What is a sarcomere? Name its regions: Smallest contractile unit (Z-disc to Z-disc). • Z-band, A-band (dark), I-band (light), H-zone. 18. What are actin and myosin? • Actin: Thin filament. • Myosin: Thick filament that pulls actin during contraction. 19. What is troponin and tropomyosin? • Tropomyosin blocks binding sites on actin. • Troponin binds Ca²⁺ to move tropomyosin and expose sites. 20. What is a motor unit? A motor neuron and all muscle fibers it controls. 21. Role of T-Tubule, SR, Terminal Cisternae: • T-Tubule: Conducts AP into cell. • SR: Stores calcium. • Terminal cisternae: Release calcium. 22. Which neurotransmitter is released at the neuromuscular junction? Acetylcholine (ACh). 23. What role does Ca²⁺ play in muscle physiology? Binds troponin, moves tropomyosin, exposes actin sites. 24. What happens to Ca²⁺ after action potential ends? Reabsorbed into SR by Ca²⁺ ATPase pump. 25. What is the function of ATP in muscle physiology? Powers myosin movement, detachment, and Ca²⁺ reuptake. 26. What is sliding filament theory? Myosin pulls actin filaments → sarcomere shortens → contraction. 27. What are DHP and Ryanodine receptors and their roles? • DHP: Voltage sensor in T-tubule. • Ryanodine: Releases Ca²⁺ from SR. 28. What is the function of AChE? Breaks down ACh to stop stimulation and contraction. 29. Difference between isotonic and isometric contractions: • Isotonic: Muscle changes length (shortens/lengthens). • Isometric: Muscle length stays same; tension builds. ⸻ Respiratory Physiology 30. Difference between conductive and respiratory divisions: • Conductive: Air passageways (nose to bronchioles). • Respiratory: Gas exchange (alveoli). 31. Type I & II alveolar cells and functions: • Type I: Gas exchange. • Type II: Secretes surfactant, repairs alveoli. 32. Dust cells and their functions: Alveolar macrophages that clean up particles/debris. 33. Muscles in relaxed vs. forced respiration: • Relaxed inhale: Diaphragm, external intercostals. • Forced inhale: Accessory neck muscles. • Forced exhale: Internal intercostals, abdominals. 34. What happens to pressure and volume when inhaling/exhaling? • Inhale: Volume ↑, pressure ↓. • Exhale: Volume ↓, pressure ↑. 35. Difference between systemic and pulmonary exchange: • Systemic: Gas exchange at tissues. • Pulmonary: Gas exchange in lungs. 36. What cells are involved in carrying gases? Red blood cells (RBCs). 37. Which enzyme converts CO₂ + H₂O → H₂CO₃? Carbonic anhydrase. 38. What does carbonic acid break into? H⁺ + HCO₃⁻ (bicarbonate ion). 39. What happens in hypoxia (low oxygen)? • ↓O₂, ↑CO₂, ↓pH (acidosis). 40. What happens in hypercapnia (high CO₂)? • ↑CO₂, ↓O₂, ↓pH (acidosis). 41. Receptors for blood pH and their locations: • Central (CSF pH): Medulla oblongata. • Peripheral (O₂, CO₂, pH): Carotid & aortic bodies. 42. CO₂ loading & O₂ unloading at tissues: • CO₂ enters blood → forms HCO₃⁻. • O₂ released to tissues. 43. CO₂ unloading & O₂ loading at alveoli: • CO₂ released from blood to lungs. • O₂ binds to hemoglobin. 44. Brain part for unconscious breathing: Medulla oblongata. 45. Obstructive vs. restrictive disorders + example: • Obstructive: Narrowed airways (asthma). • Restrictive: Reduced lung expansion (fibrosis). 46. Know spirometry volumes (not numbers): • Tidal volume, • Inspiratory/Expiratory reserve volume, • Residual volume, • Vital capacity, • Total lung capacity, • Inspiratory capacity, • Functional residual capacity. 47. Define eupnea, dyspnea, tachypnea, apnea, Kussmaul respiration: • Eupnea: Normal breathing. • Dyspnea: Labored breathing. • Tachypnea: Rapid, shallow breathing. • Apnea: No breathing

[MT] RESPIRATORY SYSTEM pt.3 (Conducting Portion - Epiglottis, Trachea, Bronchi and Terminal Bronchioles)

1 What structures make up the gas exchange system in humans? Cartilage rings Trachea Bronchi Larynx Intercostal Muscles Alveoli Diaphragm Ribs Bronchioles Trachea: Moves air from outside the body to inside the lungs. Also called the windpipe Cartilage rings: C-shaped rings that hold open the trachea. Bronchi: The trachea splits into two bronchi, that lead into each lung. Bronchioles: The bronchi split into many smaller tubes that take air throughout the lungs. Ribs: Bones that protect the lungs from damage. Alveoli: At the ends of the bronchioles, where gas exchange takes place. Intercostal muscles: The muscle between the ribs. MHS Year 10 Science - BIOLOGY 2025 How does air, containing oxygen, get into and out of the lungs? Breathing in: Diaphragm contracts and moves down, intercostal muscles contract and move ribs up and out = more space in the chest = air moves in. Breathing out: Diaphragm relaxes and moves up, intercostal muscles relax and move ribs down and in = less space in the chest = air moves out. Carbon dioxide needs to be breathed out as it is toxic and will kill cells. Oxygen needs to be breathed in as it is needed by all cells to release energy from food (respiration) What structures make up the human circulatory system? The heart has 4 chambers, two atrium at the top and 2 ventricle at the bottom. There is a left and right side of the heart. The left side has thicker muscle than the right as it pumps blood a greater distance than the right side. The septum is the muscle between the two sides. There are 3 types of blood vessels. Arteries take blood away from the heart, veins that take blood towards the heart and very thin capillaries join the arteries and veins. Blood is made of a liquid called plasma and blood cells. There are three types of blood cells, red blood cells (carry oxygen) white blood cells (prevent disease) and platelets (form blood clots). 5 What does the heart look like? Aorta Right Vent sorrenated 3 Where does oxygen get into the blood? Air containing lots of oxygen is breathed in. The air travels down the trachea, bronchi, bronchioles to the alveoli. Gas exchange takes place in the alveoli. Oxygen is needed by all cells for respiration. Oxygen moves from the air in the alveoli into the blood in the capillaries surrounding the alveoli. Carbon dioxide is made during respiration and is toxic. It is removed from the blood as it travels past the alveoli. It is removed from the body when we breathe out

Bronchioles and alveoli (copy)

Bronchioles and Alveoli

„ INTRODUCTION Medulla is the inner part of adrenal gland and it forms 20% of the mass of adrenal gland. It is made up of interlacing cords of cells known as chromaffin cells. Chromaffin cells are also called pheochrome cells or chromophil cells. These cells contain fine granules which are stained brown by potassium dichromate. Types of chromaffin cells Adrenal medulla is formed by two types of chromaffin cells: 1. Adrenaline-secreting cells (90%) 2. Noradrenaline-secreting cells (10%). „ HORMONES OF ADRENAL MEDULLA Adrenal medullary hormones are the amines derived from catechol and so these hormones are called catecholamines. Catecholamines secreted by adrenal medulla 1. Adrenaline or epinephrine 2. Noradrenaline or norepinephrine 3. Dopamine. „ PLASMA LEVEL OF CATECHOLAMINES 1. Adrenaline : 3 μg/dL 2. Noradrenaline : 30 μg/dL 3. Dopamine : 3.5 μg/dL „ HALF-LIFE OF CATECHOLAMINES Half-life of catecholamines is about 2 minutes. „ SYNTHESIS OF CATECHOLAMINES Catecholamines are synthesized from the amino acid tyrosine in the chromaffin cells of adrenal medulla (Fig. 71.1). These hormones are formed from phenylalanine also. But phenylalanine has to be converted into tyrosine. Stages of Synthesis of Catecholamines 1. Formation of tyrosine from phenylalanine in the presence of enzyme phenylalanine hydroxylase 2. Uptake of tyrosine from blood into the chromaffin cells of adrenal medulla by active transport 3. Conversion of tyrosine into dihydroxyphenylalanine (DOPA) by hydroxylation in the presence of tyrosine hydroxylase 440 Section 6tEndocrinology FIGURE 71.1: Synthesis of catecholamines. DOPA = Di- hydroxyphenylalanine, PNMT = Phenylethanolamine-N- methyltransferase. 4. Decarboxylation of DOPA into dopamine by DOPA decarboxylase 5. Entry of dopamine into granules of chromaffin cells 6. Hydroxylation of dopamine into noradrenaline by the enzyme dopamine beta-hydroxylase 7. Release of noradrenaline from granules into the cytoplasm 8. Methylation of noradrenaline into adrenaline by the most important enzyme called phenylethanolamine- N-methyltransferase (PNMT). PNMT is present in chromaffin cells. „ METABOLISM OF CATECHOLAMINES Eighty five percent of noradrenaline is taken up by the sympathetic adrenergic neurons. Remaining 15% of noradrenaline and adrenaline are degraded (Fig. 71.2). FIGURE 71.2: Metabolism of catecholamines. COMT = Catechol-O-methyltransferase, MAO = Monoamine oxidase. Stages of Metabolism of Catecholamines 1. Methoxylation of adrenaline into meta-adrenaline and noradrenaline into metanoradrenaline in the presence of ‘catechol-O-methyltransferase’ (COMT). Meta-adrenaline and meta-noradrenaline are together called metanephrines 2. Oxidation of metanephrines into vanillylmandelic acid (VMA) by monoamine oxidase (MAO) Removal of Catecholamines Catecholamines are removed from body through urine in three forms: i. 15% as free adrenaline and free noradrenaline ii. 50% as free or conjugated meta-adrenaline and meta-noradrenaline iii. 35% as vanillylmandelic acid (VMA). „ ACTIONS OF ADRENALINE AND NORADRENALINE Adrenaline and noradrenaline stimulate the nervous system. Adrenaline has significant effects on metabolic functions and both adrenaline and noradrenaline have significant effects on cardiovascular system. „ MODE OF ACTION OF ADRENALINE AND NORADRENALINE – ADRENERGIC RECEPTORS Actions of adrenaline and noradrenaline are executed by binding with receptors called adrenergic receptors, which are present in the target organs. Chapter 71tAdrenal Medulla 441 Adrenergic receptors are of two types: 1. Alpha-adrenergic receptors, which are subdivided into alpha-1 and alpha-2 receptors 2. Beta-adrenergic receptors, which are subdivided into beta-1 and beta-2 receptors. Refer Table 71.1 for the mode of action of these receptors. „ ACTIONS Circulating adrenaline and noradrenaline have similar effect of sympathetic stimulation. But, the effect of adrenal hormones is prolonged 10 times more than that of sympathetic stimulation. It is because of the slow inactivation, slow degradation and slow removal of these hormones. Effects of adrenaline and noradrenaline on various target organs depend upon the type of receptors present in the cells of the organs. Adrenaline acts through both alpha and beta receptors equally. Noradrenaline acts mainly through alpha receptors and occasionally through beta receptors. 1. On Metabolism (via Alpha and Beta Receptors) Adrenaline influences the metabolic functions more than noradrenaline. i. General metabolism: Adrenaline increases oxygen consumption and carbon dioxide removal. It increases basal metabolic rate. So, it is said to be a calorigenic hormone ii. Carbohydrate metabolism: Adrenaline increases the blood glucose level by increasing the glycogenolysis in liver and muscle. So, a large quantity of glucose enters the circulation iii. Fat metabolism: Adrenaline causes mobilization of free fatty acids from adipose tissues. Catecholamines need the presence of glucocorticoids for this action. 2. On Blood (via Beta Receptors) Adrenaline decreases blood coagulation time. It increases RBC count in blood by contracting smooth muscles of splenic capsule and releasing RBCs from spleen into circulation. 3. On Heart (via Beta Receptors) Adrenaline has stronger effects on heart than nor- adrenaline. It increases overall activity of the heart, i.e. i. Heart rate (chronotropic effect) ii. Force of contraction (inotropic effect) iii. Excitability of heart muscle (bathmotropic effect) iv. Conductivity in heart muscle (dromotropic effect). 4. On Blood Vessels (via Alpha and Beta-2 Receptors) Noradrenaline has strong effects on blood vessels. It causes constriction of blood vessels throughout the body via alpha receptors. So it is called ‘general vasoconstrictor’. Vasoconstrictor effect of noradrena- line increases total peripheral resistance. Adrenaline also causes constriction of blood vessels. However, it causes dilatation of blood vessels in skeletal muscle, liver and heart through beta-2 receptors. So, the total peripheral resistance is decreased by adrenaline. Catecholamines need the presence of glucocor- ticoids, for these vascular effects. 5. On Blood Pressure (via Alpha and Beta Receptors) Adrenaline increases systolic blood pressure by increasing the force of contraction of the heart and cardiac output. But, it decreases diastolic blood pressure by reducing the total peripheral resistance. Noradrenaline increases diastolic pressure due to general vasoconstrictor effect by increasing the total peripheral resistance. It also increases the systolic blood pressure to a slight extent by its actions on heart. The action of catecholamines on blood pressure needs the presence of glucocorticoids. TABLE 71.1: Adrenergic receptors Receptor Mode of action Response Alpha-1 receptor Activates IP3 through phospholipase C Mediates more of noradrenaline actions than adrenaline actions Alpha-2 receptor Inhibits adenyl cyclase and cAMP Beta-1 receptor Activates adenyl cyclase and cAMP Mediates actions of adrenaline and noradrenaline equally Beta-2 receptor Activates adenyl cyclase and cAMP Mediates more of adrenaline actions than noradrenaline actions IP3 = Inositol triphosphate 442 Section 6tEndocrinology Thus, hypersecretion of catecholamines leads to hypertension. 6. On Respiration (via Beta-2 Receptors) Adrenaline increases rate and force of respiration. Adrenaline injection produces apnea, which is known as adrenaline apnea. It also causes bronchodilation. 7. On Skin (via Alpha and Beta-2 Receptors) Adrenaline causes contraction of arrector pili. It also increases the secretion of sweat. 8. On Skeletal Muscle (via Alpha and Beta-2 Receptors) Adrenaline causes severe contraction and quick fatigue of skeletal muscle. It increases glycogenolysis and release of glucose from muscle into blood. It also causes vasodilatation in skeletal muscles. 9. On Smooth Muscle (via Alpha and Beta Receptors) Catecholamines cause contraction of smooth muscles in the following organs: i. Splenic capsule ii. Sphincters of gastrointestinal (GI) tract iii. Arrector pili of skin iv. Gallbladder v. Uterus vi. Dilator pupillae of iris vii. Nictitating membrane of cat. Catecholamines cause relaxation of smooth muscles in the following organs: i. Non-sphincteric part of GI tract (esophagus, stomach and intestine) ii. Bronchioles iii. Urinary bladder. 10. On Central Nervous System (via Beta Receptors) Adrenaline increases the activity of brain. Adrenaline secretion increases during ‘fight or flight reactions’ after exposure to stress. It enhances the cortical arousal and other facilitatory functions of central nervous system. 11. Other Effects of Catecholamines i. On salivary glands (via alpha and beta-2 receptors): Cause vasoconstriction in salivary gland, leading to mild increase in salivary secretion ii. On sweat glands (via beta-2 receptors): Increase the secretion of apocrine sweat glands iii. On lacrimal glands (via alpha receptors): Increase the secretion of tears iv. On ACTH secretion (via alpha receptors): Adrenaline increases ACTH secretion v. On nerve fibers (via alpha receptors): Adrenaline decreases the latency of action potential in the nerve fibers, i.e. electrical activity is accelerated vi. On renin secretion (via beta receptors): Increase the rennin secretion from juxtaglomerular apparatus of the kidney. „ REGULATION OF SECRETION OF ADRENALINE AND NORADRENALINE Adrenaline and noradrenaline are secreted from adrenal medulla in small quantities even during rest. During stress conditions, due to sympathoadrenal discharge, a large quantity of catecholamines is secreted. These hormones prepare the body for fight or flight reactions. Catecholamine secretion increases during exposure to cold and hypoglycemia also. „ DOPAMINE Dopamine is secreted by adrenal medulla. Type of cells secreting this hormone is not known. Dopamine is also secreted by dopaminergic neurons in some areas of brain, particularly basal ganglia. In brain, this hormone acts as a neurotransmitter. Injected dopamine produces the following effects: 1. Vasoconstriction by releasing norepinephrine 2. Vasodilatation in mesentery 3. Increase in heart rate via beta receptors 4. Increase in systolic blood pressure. Dopamine does not affect diastolic blood pressure. Deficiency of dopamine in basal ganglia produces nervous disorder called parkinsonism (Chapter 151). „ APPLIED PHYSIOLOGY – PHEOCHROMOCYTOMA Pheochromocytoma is a condition characterized by hypersecretion of catecholamines. Cause Pheochromocytoma is caused by tumor of chromophil cells in adrenal medulla. It is also caused rarely by tumor of sympathetic ganglia (extra-adrenal pheochromocytoma). Chapter 71tAdrenal Medulla 443 Signs and Symptoms Characteristic feature of pheochromocytoma is hyper- tension. This type of hypertension is known as endocrine or secondary hypertension. Other features: 1. Anxiety 2. Chest pain 3. Fever 4. Headache 5. Hyperglycemia 6. Metabolic disorders 7. Nausea and vomiting 8. Palpitation 9. Polyuria and glucosuria 10. Sweating and flushing 11. Tachycardia 12. Weight loss. Tests for Pheochromocytoma Pheochromocytoma is detected by measuring meta- nephrines and vanillylmandelic acid in urine and Cathecolamines in olasma

Bronchus, Bronchioles, Terminal Bronchiole

Respiratory System

Bronchi And Bronchioles

Division of Bronchi into Bronchioles

Anatomy & Physiology Respiratory Systems Quiz Diagrams - Bronchioles & Alveoli

Anatomy - 15-3: The Bronchioles

Bronchioles and alveoli

4.8 Bronchioles and Alveoli

6. Trachea, Bronchi, Bronchioles and Alveoli