all anatomy slides

Big Ideas of Anatomy and Physiology

• Structure and Function: How body parts are designed determines what they do.

• Feedback and Homeostasis: Maintaining a stable internal environment.

• Growth and Development: Changes occurring throughout life.

Control Systems

• The body responds to stimuli through control systems that coordinate and direct cell activity.

Nervous System

• Functions:

  • Higher mental function.

  • Emotional expression.

  • Maintains homeostasis.

  • Regulates activities of muscles and glands.

• Mechanism:

  • Sends electrochemical signals through nerves.

Endocrine System

• Function:

  • Regulates complex body processes like growth and development, metabolism, and reproduction.

• Mechanism:

  • Chemical messengers called hormones are released into and travel through the bloodstream.

• Organs:

  • Small and located throughout the body (e.g., pineal gland, hypothalamus, pituitary gland, thyroid gland, parathyroid glands, thymus, adrenal glands, pancreas, kidneys, testes, ovaries).

How Control Systems Coordinate Body Activity

Nervous System

• Neurons transmit signals quickly via electrical signals down axons.

• At axon terminals, neurotransmitters are released across synapses to communicate with other neurons/target cells.

Endocrine System

• Endocrine cells secrete hormones into the bloodstream.

• Signals can act on target cells from seconds to days.

Comparison of Nervous and Endocrine Systems

Types of Hormones

Amino Acid-Based Molecules

• Proteins

• Examples: Growth hormone, insulin, epinephrine, oxytocin.

Steroids

• Lipids

• Examples: Testosterone, progesterone, cortisol.

Hormone Action

• Two main mechanisms:

  • Secondary Messengers

  • Direct Gene Activation

Amino Acid-Based Hormones

• Receptor on cell membrane → cascade of chemical reactions → produce a secondary messenger → cellular responses.

Steroids

• Diffuse through the cell membrane → binds to a specific hormone receptor in the nucleus → activating/deactivating transcription of DNA.

Scientific Modelling

• Scientific models explain processes and help understand complex concepts.

Endocrine Action

1. Endocrine tissue secretes a hormone into the bloodstream. Hormones can be protein-based or steroids.

2. The hormone travels through the bloodstream to the target cells/tissues/organs.

3. Hormones interact with receptors in the target cell.

   • Protein-based hormones bind to receptors on the cell surface.

   • Steroid hormones bind to receptors inside the cell nucleus.

Stimuli for Hormone Release

• Three mechanisms control hormone release:

  • Neural Stimulus: Nerve signals stimulate hormone release.

  • Hormonal Stimulus: Hormone signals stimulate hormone release.

  • Humoral Stimulus: Changes in blood chemistry (e.g., levels of ions and nutrients) stimulate hormone release.

Case Study - Epinephrine

• The sympathetic nervous system activates the “fight or flight” response.

• Nerves send electrochemical signals (ACh) to target organs, such as:

  • Heart: Increased rate of contraction.

  • Adrenal Gland: Release epinephrine.

• Epinephrine goes into the bloodstream (indirect) → entire body effect of “fight or flight”.

Hormonal Stimulus

• Hormone signals stimulate hormone release.

• Examples:

  • Epinephrine activates receptors that increase the production of norepinephrine.

  • Pituitary gland releases thyroid-stimulating hormone (TSH) to influence the thyroid gland to release hormones.

Feedback Mechanisms

• Feedback: Response within a system that influences its continued activity.

  • Positive feedback: A hormone contributes to increased production of itself.

  • Negative feedback: A hormone contributes to decreased production of itself.

• Homeostasis: Steady conditions maintained by organisms to survive and thrive.

  • Negative feedback helps to maintain homeostasis like a thermostat.

Insulin and Glucagon

• Hormones released by the pancreas.

• Insulin leads to the uptake of blood glucose into cells.

• Glucagon leads to the breakdown of glycogen into glucose to be released into the blood.

Humoral Stimulus

• Changes in blood chemistry stimulate hormone release.

• Insulin and glucagon are stimulated by the level of glucose in the bloodstream (blood sugar).

• Blood sugar regulation is an example of negative feedback.

Endocrine Feedback and Homeostasis

• Most hormone levels are regulated through negative feedback.

• Blood levels of many hormones vary within a very narrow range.

• Positive feedback mechanisms are rare and amplify changes rather than reversing them.

• Example: Oxytocin from the pituitary gland during labor stimulates muscle contractions. The release of oxytocin results in stronger contractions until the baby is outside the birth canal. When the stimulus to the pressure receptors ends, oxytocin production stops, and labor contractions cease.

Summary of Hormone Release Mechanisms

• Three mechanisms control hormone release:

  • Neural Stimulus

  • Hormonal Stimulus

  • Humoral Stimulus

• Negative Feedback regulates hormone levels to maintain homeostasis.

• Positive Feedback regulates hormone levels during short-term responses like labor, menstrual cycle, and fight or flight responses.

Endocrine Function

1. Endocrine tissue secretes a hormone into the bloodstream. Hormones can be protein-based or steroids.

2. The hormone travels through the bloodstream to the target cells/tissues/organs.

3. Hormones interact with receptors in the target cell.

   • Protein-based hormones bind to receptors on the cell surface.

   • Steroid hormones bind to receptors inside the cell nucleus.

Endocrine Function

• Three mechanisms control hormone release:

  • Neural Stimulus

  • Hormonal Stimulus

  • Humoral Stimulus

• Negative Feedback regulates hormone levels to maintain homeostasis.

• Positive Feedback regulates hormone levels during short-term responses like labor, menstrual cycle, and fight or flight responses.

• Still to finish learning: Major Endocrine Organs and Hormones

Blood Basics

• Blood is the only liquid tissue in the body, made of both solid and liquid components.

• Transports nutrients, hormones, waste, and body heat through blood vessels.

• pH is slightly basic (7.35-7.45).

• Temperature is ~$101.4^{\circ}F$ (higher than normal body temp).

• Normal adult volume = ~5-6 liters.

Centrifuge

• Centrifuges can separate blood components based on density.

• Solid components precipitate on the bottom, while liquid components sit on top.

Blood Components

• Hematocrit: The volume (%) of packed elements (mainly red blood cells) in a blood sample.

1. ~55% Plasma:

   • Liquid (>92% water) with dissolved proteins.

2. ~45% Erythrocytes:

   • Red blood cells (RBCs).

3. <1% other formed elements:

   • Leukocytes: White blood cells (WBCs).

   • Platelets: Cell fragments.

Examining Hematocrits

• Clinical relevance:

  • Provides information about the oxygen-carrying capacity of blood. Low hematocrit means less red blood cells carrying $O_2$.

• Healthy ranges:

  • Male: 42%-52% hematocrit.

  • Female: 37%-47% hematocrit.

• Anemia:

  • Decrease in the oxygen-carrying capacity of blood.

• Polycythemia:

  • Increase in RBCs; blood is too thick.

Investigation - Microscopy

• Find and draw each of the main solid components of blood:

1. Erythrocytes

2. Leukocytes

3. Platelets

Microscopy - Structure and Function

Erythrocytes (RBCs)

• Carry oxygen throughout the body.

  • Contain hemoglobin - a protein that carries oxygen.

  • Donut shape - better for gas exchange.

  • No nucleus or mitochondria - more room for hemoglobin.

Leukocytes (WBCs)

• Combat pathogens.

  • Complete cells with nuclei and organelles.

  • Can leave the bloodstream.

  • Increase production in response to infection.

Platelets

• Contribute to blood clotting.

  • Fragments of bigger multinucleate cells.

Blood Functions - RBCs

• Red Blood Cells transport oxygen bound to hemoglobin proteins.

• ~5 million cells in a cubic mm of blood, and each cell has ~1 billion oxygen molecules.

• Lifespan: 100 to 120 days.

RBC Disorders

• Anemia: decrease in the oxygen-carrying capacity of blood

  • Iron deficiency anemia: lack of iron in diet → lack of hemoglobin.

  • Sickle cell anemia: genetic disorder causes abnormal hemoglobin

Blood Functions - WBCs

• ~4k-10k cells in every cubic mm of blood

• 2 main types:

  • Granulocytes: Neutrophils, Eosinophils, Basophils

  • Agranulocytes: Lymphocytes, Monocytes

• Form part of the Body Defenses (Unit 10)

Blood Review

1. Plasma

   • Water

   • Plasma proteins

   • Dissolved nutrients

2. Formed Elements

   • Erythrocytes (RBCs)

   • Leukocytes (WBCs)

   • Platelets

• Anemia: decrease in the oxygen-carrying capacity of blood

• Polycythemia: increase in RBCs; blood is too thick

Hematopoiesis

• Blood cells are formed (hematopoiesis) in the red bone marrow tissue.

• All formed elements differentiate from one stem cell - the hemocytoblast.

• RBCs:

  • Short life cycle (100-120 days) and minimal functionality (no organelles).

  • Process of RBC formation is stimulated by erythropoietin (a hormone).

Erythropoietin Pathway

• Stimulus: Low levels of blood oxygen.

• Released by the kidney to target red bone marrow tissue.

• Is the erythropoietin pathway negative or positive feedback?

WBCs and Platelets

• WBCs:Hormones stimulate production of WBCs in response to pathogens in the body.

• Platelets: Stem cell (megakaryocyte) fragments to produce platelets.

Hemostasis

• Normally, blood flows smoothly past the vascular endothelium of blood vessels. When the blood vessels break, hemostasis starts.

1. Vascular spasms:

   • Immediate; vasoconstriction reduces blood loss.

2. Platelet plug forms:

   • Platelets are normally repelled by the vascular endothelium. When collagen fibers are exposed, platelets stick/anchor to them, forming a makeshift plug.

3. Coagulation (clotting):

   • Chain reaction; Tissues release enzymes (thrombin and fibrinogen) to produce long fibrin molecules. Fibrin forms a mesh and traps RBCs, forming the clot.

4. Endothelium Tissue Repair

Medical Treatments for Hemostasis

1. Dressing wounds:

   • Creates a rough surface for platelets to stick to and fibrin to attach to. Applying pressure stimulates release of clotting factors and enzymes.

2. Anticoagulants:

   • Breaks up the chain reaction in coagulation. Used in medical blood bags, sample tubes, and dialysis equipment. Ex - Warfarin and Heparin

3. Antiplatelet drugs:

   • Prevents platelets from clumping together.

Hemostasis Disorders

Too Much Hemostasis

• Thrombus:

  • Clot that develops in an unbroken blood vessel (undesirable). May prevent blood flow -example- pulmonary thrombosis.

• Embolus:

  • If a thrombus breaks free and floats freely in the bloodstream -example- cerebral embolism (stroke)

Not Enough Hemostasis

• Thrombocytopenia:

  • Insufficient number of platelets in the blood.

• Hemophilia:

  • Genetic disorder → lack of coagulant factors

Antigens and Blood Types

• All cells have antigens - membrane protein markers

• Antigens mark cells as belonging to the body. This is part of the immune response to foreign pathogens.

• Antibodies present in blood plasma bind with antigens to cause agglutination and “mark” foreign cells for destruction.

• Blood types are determined by the presence of different antigens on red blood cells.

• A, B, AB, O +- Example - a person with A+ blood type has both A antigens and Rh antigens

• What antibodies would this person produce? Why?

• Practice - A person has AB- blood type. What antigens and antibodies do they have?

Transfusions

• Which blood should you give your patients?

• Blood can be received by a patient when the patient doesn’t produce the antibodies against it.

• AB+ people produce no antibodies, so they are considered “universal recipients”.

• O- blood cells have no antigens, so they are considered “universal donors”.

Heart Anatomy Review

• The heart is enclosed in the pericardium for support and protection.

• The heart wall has 3 layers - epicardium, myocardium, endocardium

• The heart functions as a double pump -

  • The right ventricle is the pulmonary pump (right ventricle to lungs to left atrium)

  • The left ventricle is the systemic pump (left ventricle to body tissues to right atrium)

Heart Beat Procedures

• Three possible procedures to measure the heart beat of a patient:

1. Checking carotid/radial artery pulse - heart rate lab

2. Use a stethoscope to listen for sounds the heart makes

3. Use electrocardiography (ecg/ekg) to measure the electrical activity of the heart

Electrical vs Mechanical Signals

• Procedure 1 measures arterial pulse - arterial response to the heart beating

• Procedure 2 (stethoscope) measures the mechanical action behind the heart beating (more to come later)

• Procedure 3 (ECG/EKG) measures the electrical activity of the heart.

Heart Beat Regulation

• 2 systems regulate heart activity:

1. Autonomic nervous system controls

2. Intrinsic Conduction System (or Nodal System) - Specialized cardiac cells that establish the heart rate

ECG Reading

• Electrical signal travels from the sinoatrial (SA) node through the atrium walls, causing contraction of the atria.

• The signal pauses at the atrioventricular (AV) node, before traveling rapidly through the AV bundle, bundle branches, and Purkinje fibers in the ventricular wall, causing contraction of the ventricles.

Heart Beat Anatomy

• Stethoscope - measures the mechanical properties of a heart beat

• 2 distinct sounds: “lub” and “dup” lub dup pause, lub dup pause, etc.

• Cardiac Cycle - events of one complete heartbeat (60-100 bpm)

Heart Terms

• Systole - Contraction stages

• Diastole - Relaxation stages

• 5 events of the cardiac cycle (board diagram)

Heart Valve Sounds

• Heart sounds result from the closing of valves (“lub-dup”)

• Faulty valves reduce efficiency of the heart and result in abnormal heart sounds (heart murmurs)

• ECGs can also measure heart disorders

Heart Anatomy Review

• Atrioventricular (AV) valves prevent backflow into the atria when ventricles are contracting

• Semilunar (SL) valves prevent backflow into the ventricles when they are relaxing

• Sinoatrial (SA) node is the pacemaker. Sets a heart rate of around 75 bpm

• Atria help fill ventricles, ventricles eject blood into major vessels

• Heartbeats can be measured electrically (ECG/EKG) or by sound (stethoscope)

Heart Action Review

• Atrioventricular (AV) valves prevent backflow into the atria when ventricles are contracting

• Semilunar (SL) valves prevent backflow into the ventricles when they are relaxing

• Sinoatrial (SA) node is the pacemaker. Sets a basic heart rate of around 75 bpm

• Atria help fill ventricles, ventricles eject blood into major vessels

• Heartbeats can be measured electrically (ECG/EKG) or by sound (stethoscope)

Heart Rate Factors

• Basic Heart Rate - intrinsic conduction system maintains the contraction of heart muscle (60-100 bpm)

• 3 major ways to change the rate of heart muscle contraction:

  • Neural Controls (ANS) - Sympathetic nervous system activates the SA/AV nodes and the heart muscle itself. More contractions → more blood flow → more oxygen in tissues

  • Hormones - Epinephrine and thyroxine increase heart rate.

  • Ions - Calcium and Potassium are important for muscle contraction.

1. Physical factors - age (-), sex, exercise (+), and body temperature (+) all influence heart rate

Cardiovascular System

Components:

• Heart

• Blood Vessels

Functions:

• Transportion

  • Delivers nutrients - oxygen, glucose, hormones

  • Removes waste - carbon dioxide, lactic acid

Heart Wall and Action

• Pericardium - Fluid-filled sac that surrounds and protects the heart

• Heart Wall:

  • Epicardium - outermost layer of the heart

  • Myocardium - cardiac muscle tissue that causes heart contractions

  • Endocardium - innermost layer of the heart; forms surface of valves

• The heart has 4 hollow cavities (chambers) for blood.

  • 2 atria (atriums) - receive blood from veins

  • 2 ventricles - send blood through arteries

Circulation Function

• The heart is enclosed in the pericardium for support and protection.

• The heart wall has 3 layers - epicardium, myocardium, endocardium

• The heart functions as a double pump -

  • The right ventricle is the pulmonary pump (right ventricle to lungs to left atrium)

  • The left ventricle is the systemic pump (left ventricle to body tissues to right atrium)

Blood Pressure

• Pressure the blood exerts on the inner walls of blood vessels.

• - measured in mmHg

• When ventricles contract, they force blood into the elastic, thick-walled arteries.

• High or low blood pressure?

• Blood flows from high to low pressure areas

• Blood flows from arteries → arterioles → capillaries → venules → veins

• Pressure gradient (high to low) along the direction of blood flow

Blood Pressure Impacts

• Peripheral Resistance - the resistance blood experiences as it flows -

  • Constriction of blood vessels (vasoconstriction or atherosclerosis) -

  • Increase in blood viscosity

• Hypotension (low blood pressure) - systolic < 100; consequence of aging

• Hypertension (high blood pressure) - systolic >140; common and dangerous disorder (chronic); factors like diet, heredity, stress all can contribute

Blood Pressure Review

• Arteries transport blood away from the heart ○ Artery walls are thick and strong to withstand blood pressure fluctuations

• Veins carry blood back to the heart ○ Vein walls are thinner, lumens are larger, and veins have valves

• Capillaries are exchange vessels

• Blood pressure provides the force for blood to flow. Systolic and diastolic pressure are recorded when blood pressure is measured.

• Hypertension (high blood pressure) results from an increase in peripheral resistance, strains the heart, and damages blood vessels

Digestive System Functions:

1. Breakdown (digest) food

2. absorb nutrients from food

3. Excrete waste products

• Two primary ways food is digested:
  Mechanical digestion - physically breaking food into smaller pieces
  Chemical digestion - enzymes break down macromolecules (carbohydrates, fats, proteins) into smaller pieces
  Small molecules are absorbed into the bloodstream to be transported to body tissues

Digestive System Review

Digestive System Functions:

1. Breakdown (digest) food

2. absorb nutrients from food

3. Excrete waste products
   For each of the 3 functions of the digestive system, list structures that contribute to that function.

Lymphatic System

• Excess Interstitial Fluid (IF) is captured and returned to the blood stream.

• Edema occurs when excess fluid accumulates in tissues.

Lymphatic Balance and Defenses

1. Fluid Balance
   *The lymphatic system carries excess interstitial fluid from tissues back to the circulatory systems.
   *Lymph - clearish/yellowish fluid carried by the lymphatic system.
   Lymph capillary → lymph collecting vessels → lymph nodes → lymph trunks → lymph ducts → veins

2. Body Defenses (Immune System)

Lymphatic Functions and Lymph Nodes

• The lymphatic system carries excess interstitial fluid from tissues back to the circulatory systems.

• Lymph - clearish/yellowish fluid carried by the lymphatic system.

• Lymph capillary → lymph collecting vessels → lymph nodes → lymph trunks → lymph ducts → veins

• Lymph nodes remove foreign substances (like bacteria and tumor cells) from lymph. Lymph nodes also store lymphocytes - specialized cells involved in the immune response.

• Pathogens - any organism or agent that can produce disease. (germ)

Immune System

• Immune System - functional (physiological) system that combines functions from multiple body systems

• Innate defense system - nonspecific; protects the body from all foreign substances

• Adaptive defense system - specific; targets one or more particular foreign substances

• The immune system protects us from bacteria, viruses, transplanted organs/tissues, cancer cells

• Immunity - highly specific resistance to disease Environmental Cultures Lab

Environmental Cultures Lab - Culture

• Collection of growing microorganisms

• Bacteria grow fast and are ubiquitous

1. Label the bottom of your petri dish with group name and divide into 4 labeled quadrants

2. Come up with 4 sample sites around NDA you and your group wants to test for bacteria

3. In your notebook, record your independent, dependent, several control variables, and a hypothesis of which sample will see the most growth.

Sampling Procedure

1. Wet sterile swab 2. Gather sample 3. Spread sample on plate 4. Tape edge of plate and place upside down in $37^{\circ}C$ incubator

|Innate (nonspecific) defense mechanisms|Adaptive (specific) defense mechanisms|
|---|
|First line of defense
Skin
Mucous membranes
Secretions of skin and mucous membranes
The inflammatory response
Fever|

Culture Bacteria

• Is where only bacteria get on the plate until the next class

Immunity Basics

• Innate(nonspecific) defence mechanisms

• First line of defence-skin, mucous membranes,secretion of skin and mucous membrane

• Second line of defence- phagocytic cells,natural killer cells, antimicrobial proteins,the inflammatory response,fever

The body is defended from constant bacterial infection

• The immune system is a functional(physiological)system that combines functions from multiple body system . Innate defence system and Adaptive defence system that protects us bacteria transplanted transplant organs tissues cancer cells . Immunity is a highly specific resistance to disease . Innate non specific defence mechanisms First line of defence- Skin, mucous membrane ,secretions of skin,mucous membrane. Second line of defence - cells, Natural killer cells,Anitimirbial proteins, the imflamatory response,

Immune Structure Review

Review
What does it mean for bacteria to be ubiquitous?
What makes the innate defense system non-specific?
What characteristics of pathogens might make them able to resist the innate defense system?

1st line of Defence,2nd line of Defence

Innate Defence System 1st Line of Defence
Skin and Mucous Membranes 2nd Line of Defence NK cells and Phagocytes Antimicrobial proteins Fever Inflammatory Response

Double Edged Sword

A Double-Edged Sword and inflammation and your health 1 . Summarize the main point of the article 2. Explain how information forms part of the second line of defence in the immune system 3. Why do some researchers consider information to contricute to cancer 4 design experiment that can to test effect of ininformation on the body A. Independent v variable B Dependent variable C. Hypothesis

Fever Stations

Fever Investigation activity percentage represents the total function of biological processes carried out by enzymes in a cell . 1 . What graph has have you identified the independent and dependent variables 2 . Describe as well as cell function art regular human body temperature degree celsius 3 . In a fever response, the human body temperature Rises up to degrees celsius Predict what a effect a fever might have on pathogens in a body

Pathology Investigation

Innate defence mechanisms first line of defence
Skin mucous membrane secretion of skin and mucous membrane Second line of defence,phagocytic cellnatural killer cells and antimicrobial proteins the inflammatory response fever

Flu Shot Defenses

You are constantly coming into constavte with.   You freind are scared they develop an infection. 1 . Are yoou afriad you will agree with freind ,Why ar Why not? Explian you body miht be able to defend. agisnst the stphylococcus epidemidis.

|Adaptive (specific) defense
mechanisms|
|---|---|
|• Lymphocytes • Antibodies
Macrophages and other antigen-presenting cells|

Dr.Francis and Dr.Salk set up

Francis and Dr Salk and prevented and influenza out breaks in ww2 2 Experiment to determinant the cause ofinfluenza

Adaptive Defense System

People People Less Likely. Like penicillin were ineffective adaptive defense system the body's Third Line defence. how can we can prepare the adapted adapted fence since to be ready to virus it has not been exposed to

Immunity Diseases

Francis and Salk develop develop a weekend version influenza that for the 1st it will vaccine for disease can we get polio vaccine and effective is how can we design safe vaccination

Vaccination Analysis

vaccination analsis is is poliovirus contrafact polio does polio contact support review practice explain Basel to get another Flu vaccine Review practice Review

Big Ideas of Anatomy and Physiology

• Structure and Function: How body parts are designed determines what they do. This includes both macroscopic (anatomical) and microscopic (physiological) levels of organization. The arrangement of tissues in an organ dictates its function, while cellular structures enable specific physiological processes. For instance, the thin walls of alveoli in the lungs facilitate gas exchange, and the structure of a neuron allows for rapid signal transmission.

• Feedback and Homeostasis: Maintaining a stable internal environment despite external changes. Homeostasis is crucial for optimal cell function. The body uses feedback mechanisms, both negative and positive, to regulate temperature, blood glucose levels, blood pressure, and other vital parameters. Disruptions in homeostasis can lead to disease.

• Growth and Development: Changes occurring throughout life, from conception to old age. These include cell differentiation, tissue organization, and organ maturation. Growth involves increases in size, while development encompasses the functional maturation of tissues and organs. Development is influenced by genetic factors, hormones, and environmental conditions.

Control Systems

• The body responds to stimuli through control systems that coordinate and direct cell activity. These systems involve receptors, control centers, and effectors working together to maintain homeostasis. Control systems can be either local (acting within a specific tissue) or systemic (involving multiple organs).

Nervous System

• Functions:

  • Higher mental function: Cognition, memory, and reasoning.

  • Emotional expression: Generation and regulation of emotions through neural circuits.

  • Maintains homeostasis: Regulates vital parameters such as heart rate, breathing rate, and body temperature.

  • Regulates activities of muscles and glands: Controls both voluntary and involuntary actions through neural pathways.

  ---

• Mechanism: Sends electrochemical signals through nerves. Neurons transmit electrical impulses along their axons. When the impulse reaches the axon terminal, it triggers the release of neurotransmitters, which diffuse across the synapse to bind with receptors on the target cell membrane, initiating a response.

  ---

Endocrine System

• Function: Regulates complex body processes like growth and development, metabolism, and reproduction. Hormones coordinate long-term processes and maintain internal balance.

  ---

• Mechanism: Chemical messengers called hormones are released into and travel through the bloodstream. Hormones bind to specific receptors on target cells to initiate changes in cellular function. The endocrine system's effects are generally slower but more prolonged compared to the nervous system.

  ---

• Organs: Small and located throughout the body (e.g., pineal gland, hypothalamus, pituitary gland, thyroid gland, parathyroid glands, thymus, adrenal glands, pancreas, kidneys, testes, ovaries). Each organ secretes specific hormones that regulate distinct physiological processes.

  ---

How Control Systems Coordinate Body Activity

Nervous System

• Neurons transmit signals quickly via electrical signals down axons. The myelin sheath around axons increases the speed of signal transmission. Signal conduction is also influenced by axon diameter and temperature.

• At axon terminals, neurotransmitters are released across synapses to communicate with other neurons/target cells. Neurotransmitters can be excitatory (stimulating the target cell) or inhibitory (suppressing the target cell). The type of neurotransmitter released determines the nature of the response.

Endocrine System

• Endocrine cells secrete hormones into the bloodstream. Blood carries hormones. Capillaries are near endocrine cells for proper hormone secretion.

• Signals can act on target cells from seconds to days. The duration depends on the type of hormone and the target cell's response mechanisms.

Comparison of Nervous and Endocrine Systems

Types of Hormones

Amino Acid-Based Molecules

• Proteins

• Examples: Growth hormone, insulin, epinephrine, oxytocin. These hormones often act via second messenger systems due to their inability to cross the cell membrane.

Steroids

• Lipids

• Examples: Testosterone, progesterone, cortisol. Steroid hormones can diffuse through the cell membrane and bind to intracellular receptors, directly influencing gene expression.

Hormone Action

• Two main mechanisms:

  • Secondary Messengers

  • Direct Gene Activation

  ---

Amino Acid-Based Hormones

• Receptor on cell membrane → cascade of chemical reactions → produce a secondary messenger → cellular responses. This process involves G proteins, cAMP, and other intracellular signaling molecules that amplify the hormonal signal.

Steroids

• Diffuse through the cell membrane → binds to a specific hormone receptor in the nucleus → activating/deactivating transcription of DNA. This mechanism directly influences gene expression, leading to changes in protein synthesis.

Scientific Modelling

• Scientific models explain processes and help understand complex concepts. These models can be physical, mathematical, or conceptual and are used to simulate and predict biological phenomena.

Endocrine Action

1. Endocrine tissue secretes a hormone into the bloodstream. Hormones can be protein-based or steroids.

2. The hormone travels through the bloodstream to the target cells/tissues/organs. The circulatory system ensures hormones reach distant target sites.

3. Hormones interact with receptors in the target cell.

   • Protein-based hormones bind to receptors on the cell surface.

   • Steroid hormones bind to receptors inside the cell nucleus.

   ---

Stimuli for Hormone Release

• Three mechanisms control hormone release:

  • Neural Stimulus: Nerve signals stimulate hormone release.

  • Hormonal Stimulus: Hormone signals stimulate hormone release.

  • Humoral Stimulus: Changes in blood chemistry (e.g., levels of ions and nutrients) stimulate hormone release.

  ---

Case Study - Epinephrine

• The sympathetic nervous system activates the “fight or flight” response. This response prepares the body for intense physical activity.

• Nerves send electrochemical signals (ACh) to target organs, such as:

  • Heart: Increased rate of contraction.

  • Adrenal Gland: Release epinephrine.

  ---

• Epinephrine goes into the bloodstream (indirect) → entire body effect of “fight or flight”. Increases heart rate, dilates airways, and mobilizes energy stores.

Hormonal Stimulus

• Hormone signals stimulate hormone release.

• Examples:

  • Epinephrine activates receptors that increase the production of norepinephrine.

  • Pituitary gland releases thyroid-stimulating hormone (TSH) to influence the thyroid gland to release hormones. TSH stimulates the thyroid to produce thyroxine (T4) and triiodothyronine (T3), which regulate metabolism.

  ---

Feedback Mechanisms

• Feedback: Response within a system that influences its continued activity.

  • Positive feedback: A hormone contributes to increased production of itself.

  • Negative feedback: A hormone contributes to decreased production of itself.

  ---

• Homeostasis: Steady conditions maintained by organisms to survive and thrive.

  • Negative feedback helps to maintain homeostasis like a thermostat. It detects deviations from the set point and initiates corrective responses.

  ---

Insulin and Glucagon

• Hormones released by the pancreas.

• Insulin leads to the uptake of blood glucose into cells. It promotes the conversion of glucose to glycogen for storage in the liver and muscles.

• Glucagon leads to the breakdown of glycogen into glucose to be released into the blood. It elevates blood glucose levels.

Humoral Stimulus

• Changes in blood chemistry stimulate hormone release.

• Insulin and glucagon are stimulated by the level of glucose in the bloodstream (blood sugar). Regulation of blood glucose involves intricate interactions between these two hormones.

• Blood sugar regulation is an example of negative feedback. High blood sugar levels lead to insulin release, which reduces blood sugar levels. Low blood sugar levels trigger glucagon release, increasing blood sugar levels.

Endocrine Feedback and Homeostasis

• Most hormone levels are regulated through negative feedback. This ensures stability and prevents excessive hormone production.

• Blood levels of many hormones vary within a very narrow range. Maintaining this narrow range is crucial for proper physiological function.

• Positive feedback mechanisms are rare and amplify changes rather than reversing them. They are typically involved in processes that need to reach a critical threshold.

• Example: Oxytocin from the pituitary gland during labor stimulates muscle contractions. The release of oxytocin results in stronger contractions until the baby is outside the birth canal. When the stimulus to the pressure receptors ends, oxytocin production stops, and labor contractions cease. This example demonstrates how positive feedback drives a process to completion and is then shut off.

Summary of Hormone Release Mechanisms

• Three mechanisms control hormone release:

  • Neural Stimulus

  • Hormonal Stimulus

  • Humoral Stimulus

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• Negative Feedback regulates hormone levels to maintain homeostasis. It ensures that hormone concentrations remain within optimal ranges.

• Positive Feedback regulates hormone levels during short-term responses like labor, menstrual cycle, and fight or flight responses. These responses require amplification of signals over a limited period.

Endocrine Function

1. Endocrine tissue secretes a hormone into the bloodstream. Hormones can be protein-based or steroids.

2. The hormone travels through the bloodstream to the target cells/tissues/organs. Blood vessels deliver hormones throughout the body.

3. Hormones interact with receptors in the target cell.

   • Protein-based hormones bind to receptors on the cell surface.

   • Steroid hormones bind to receptors inside the cell nucleus.

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Endocrine Function

• Three mechanisms control hormone release:

  • Neural Stimulus

  • Hormonal Stimulus

  • Humoral Stimulus

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• Negative Feedback regulates hormone levels to maintain homeostasis. This feedback maintains optimal internal conditions.

• Positive Feedback regulates hormone levels during short-term responses like labor, menstrual cycle, and fight or flight responses. Here, hormonal levels serve specific purposes.

• Still to finish learning: Major Endocrine Organs and Hormones. These include the specific hormones secreted by each gland and their effects on target organs.

Blood Basics

• Blood is the only liquid tissue in the body, made of both solid and liquid components. Its unique composition allows it to perform crucial functions.

• Transports nutrients, hormones, waste, and body heat through blood vessels. The circulatory system works intimately with the blood to carry substances from one place to another efficiently.

• pH is slightly basic (7.35-7.45). Maintaining the blood pH within this range is crucial for protein structure and function.

• Temperature is $\sim$101.4^{\circ}F$(higher than normal body temp). Blood helps dissipate body heat.</p></li><li><p>Normal adult volume = ~5-6 liters. Sufficient blood volume is essential for maintaining blood pressure and ensuring proper tissue perfusion.</p></li></ul><div data-type="horizontalRule"><hr></div><h4 id="d7fad631-db46-42b4-9f7b-0c1d678902a3" data-toc-id="d7fad631-db46-42b4-9f7b-0c1d678902a3" collapsed="false" seolevelmigrated="true">Centrifuge</h4><ul><li><p>Centrifuges can separate blood components based on density. This technique is commonly used in clinical laboratories to analyze blood samples.</p></li><li><p>Solid components precipitate on the bottom, while liquid components sit on top. This allows for easy visualization and quantification of each blood component.</p></li></ul><div data-type="horizontalRule"><hr></div><h4 id="67d9173a-7935-404d-afcb-abfd2444736f" data-toc-id="67d9173a-7935-404d-afcb-abfd2444736f" collapsed="false" seolevelmigrated="true">Blood Components</h4><ul><li><p>Hematocrit: The volume ($O_2$$.

Investigation - Microscopy

• Find and draw each of the main solid components of blood:

1. Erythrocytes

2. Leukocytes

3. Platelets

Microscopy - Structure and Function

Erythrocytes (RBCs)

• Carry oxygen throughout the body.

  • Contain hemoglobin - a protein that carries oxygen. Hemoglobin binds oxygen in the lungs and releases it in tissues.

  • Donut shape - better for gas exchange. The biconcave shape increases surface area for efficient diffusion of oxygen and carbon dioxide.

  • No nucleus or mitochondria - more room for hemoglobin. The absence of these organelles maximizes the space available for hemoglobin, enhancing oxygen-carrying capacity.

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Leukocytes (WBCs)

• Combat pathogens.

  • Complete cells with nuclei and organelles. WBCs are capable of diapedesis, allowing them to move out of blood vessels into tissues.

  • Can leave the bloodstream. This migration enables WBCs to reach infection sites and mount an immune response.

  • Increase production in response to infection. Leukocytosis, or an elevated WBC count, is a common sign of infection.

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Platelets

• Contribute to blood clotting.

  • Fragments of bigger multinucleate cells. Platelets release factors that initiate the coagulation cascade, leading to clot formation.

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Blood Functions - RBCs

• Red Blood Cells transport oxygen bound to hemoglobin proteins. Hemoglobin is composed of four subunits, each containing a heme group with an iron atom that binds oxygen.

• ~5 million cells in a cubic mm of blood, and each cell has ~1 billion oxygen molecules. This high concentration ensures efficient oxygen delivery to tissues.

• Lifespan: 100 to 120 days. Aged or damaged RBCs are removed from circulation by macrophages in the spleen and liver.

RBC Disorders

• Anemia: decrease in the oxygen-carrying capacity of blood

  • Iron deficiency anemia: lack of iron in diet → lack of hemoglobin. Iron is a critical component of hemoglobin and is necessary for oxygen binding.

  • Sickle cell anemia: genetic disorder causes abnormal hemoglobin. Sickle-shaped RBCs are fragile and can block blood vessels, causing pain and organ damage.

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Blood Functions - WBCs

• ~4k-10k cells in every cubic mm of blood. Maintaining this range is crucial for proper immune function.

• 2 main types:

  • Granulocytes: Neutrophils, Eosinophils, Basophils. These WBCs contain granules filled with enzymes and other mediators that are released during an immune response.

  • Agranulocytes: Lymphocytes, Monocytes. These WBCs lack prominent granules and play crucial roles in adaptive immunity and phagocytosis.

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• Form part of the Body Defenses (Unit 10). WBCs work together to detect and eliminate pathogens and abnormal cells.

Blood Review

1. Plasma

   • Water

   • Plasma proteins

   • Dissolved nutrients

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2. Formed Elements

   • Erythrocytes (RBCs)

   • Leukocytes (WBCs)

   • Platelets

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• Anemia: decrease in the oxygen-carrying capacity of blood

• Polycythemia: increase in RBCs; blood is too thick

Hematopoiesis

• Blood cells are formed (hematopoiesis) in the red bone marrow tissue. This process occurs continuously to replenish blood cells.

• All formed elements differentiate from one stem cell - the hemocytoblast. The hemocytoblast gives rise to all lineages of blood cells.

• RBCs:

  • Short life cycle (100-120 days) and minimal functionality (no organelles). This high turnover rate necessitates continuous RBC production.

  • Process of RBC formation is stimulated by erythropoietin (a hormone). Erythropoietin targets red bone marrow to increase RBC production.

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Erythropoietin Pathway

• Stimulus: Low levels of blood oxygen.

• Released by the kidney to target red bone marrow tissue. The kidneys detect hypoxia and respond by producing erythropoietin.

• Is the erythropoietin pathway negative or positive feedback? It is negative because increased RBC production leads to increased blood oxygen levels, which then inhibit further erythropoietin release.

WBCs and Platelets

• WBCs: Hormones stimulate production of WBCs in response to pathogens in the body. Cytokines and growth factors regulate WBC production in response to infection or inflammation.

• Platelets: Stem cell (megakaryocyte) fragments to produce platelets. Megakaryocytes reside in the bone marrow and undergo fragmentation to release platelets into circulation.

Hemostasis

• Normally, blood flows smoothly past the vascular endothelium of blood vessels. Healthy endothelium releases factors that prevent platelet activation and coagulation.
  When the blood vessels break, hemostasis starts.

1. Vascular spasms:

   • Immediate; vasoconstriction reduces blood loss. Smooth muscle contraction in the vessel walls narrows the lumen to minimize blood flow.

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2. Platelet plug forms:

   • Platelets are normally repelled by the vascular endothelium. Platelets adhere to collagen exposed during breaks.
     When collagen fibers are exposed, platelets stick/anchor to them, forming a makeshift plug.

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3. Coagulation (clotting):

   • Chain reaction; Tissues release enzymes (thrombin and fibrinogen) to produce long fibrin molecules. Enzymes are released to catalyze fibrin formation.
     Fibrin forms a mesh and traps RBCs, forming the clot.

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4. Endothelium Tissue Repair - New cells replaces damaged ones.

Medical Treatments for Hemostasis

1. Dressing wounds:

   • Creates a rough surface for platelets to stick to and fibrin to attach to. A sterile dressing provides a surface for clot development and keeps the wound clean.
     Applying pressure stimulates release of clotting factors and enzymes. Pressure constricts blood vessels and promotes clot formation.

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2. Anticoagulants:

   • Breaks up the chain reaction in coagulation. Anticoagulants prevent excessive clotting in medical equipment and blood samples.
     Used in medical blood bags, sample tubes, and dialysis equipment. Ex - Warfarin and Heparin. Warfarin inhibits vitamin K-dependent clotting factors, while heparin enhances antithrombin activity.

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3. Antiplatelet drugs:

   • Prevents platelets from clumping together. These drugs reduce the risk of clot formation in individuals at risk for heart attack or stroke.

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Hemostasis Disorders

Too Much Hemostasis

• Thrombus:

  • Clot that develops in an unbroken blood vessel (undesirable). Thrombi can obstruct blood flow within the vessel.
    May prevent blood flow -example- pulmonary thrombosis. A pulmonary embolism occurs when a thrombus travels to the lungs, blocking pulmonary arteries.

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• Embolus:

  • If a thrombus breaks free and floats freely in the bloodstream -example- cerebral embolism (stroke) A cerebral embolism occurs when an embolus blocks blood flow to the brain, causing a stroke.

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Not Enough Hemostasis

• Thrombocytopenia:

  • Insufficient number of platelets in the blood, leading to impaired clot formation and increased bleeding risk.

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• Hemophilia:

  • Genetic disorder → lack of coagulant factors, resulting in prolonged bleeding after injury.

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Antigens and Blood Types

• All cells have antigens - membrane protein markers. Antigens are genetically determined and are unique to each individual.

• Antigens mark cells as belonging to the body. Immune system recognizes self to allow it to not attack itself.
  This is part of the immune response to foreign pathogens. Adaptive immune systems only attack foreign invaders.

• Antibodies present in blood plasma bind with antigens to cause agglutination and “mark” foreign cells for destruction. Agglutination facilitates phagocytosis and destruction of foreign cells.

• Blood types are determined by the presence of different antigens on red blood cells. ABO and Rh blood typing are the most clinically relevant.

• A, B, AB, O +-. The Rh factor (positive or negative) is another key antigen on RBCs.
  Example - a person with A+ blood type has both A antigens and Rh antigens. Being RH postivie means you can't produce anti-RH antibodies.

• What antibodies would this person produce? Why? This person would produce anti-B antibodies because they do not have the B antigen.

• Practice - A person has AB- blood type. What antigens and antibodies do they have? This person has A and B antigens but no Rh antigen. Therefore, they produce anti-Rh antibodies.

Transfusions

• Which blood should you give your patients? Compatibility is determined by the presence or absence of antigens and antibodies.

• Blood can be received by a patient when the patient doesn’t produce the antibodies against it. The immune system will attack incompatible blood, leading to transfusion reactions.

• AB+ people produce no antibodies, so they are considered “universal recipients”. They can receive blood from any blood type without risk of reaction.

• O- blood cells have no antigens, so they are considered “universal donors”. They can donate blood to any blood type without causing a reaction.

Heart Anatomy Review

• The heart is enclosed in the pericardium for support and protection. The pericardium consists of two layers: the fibrous pericardium and the serous pericardium.

• The heart wall has 3 layers - epicardium, myocardium, endocardium. Each layer performs distinct functions.

• The heart functions as a double pump -

  • The right ventricle is the pulmonary pump (right ventricle to lungs to left atrium). This circuit oxygenates the blood in the lungs.

  • The left ventricle is the systemic pump (left ventricle to body tissues to right atrium). This circuit delivers oxygenated blood to body tissues.

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Heart Beat Procedures

• Three possible procedures to measure the heart beat of a patient:

1. Checking carotid/radial artery pulse - heart rate lab. This method is simple and non-invasive.

2. Use a stethoscope to listen for sounds the heart makes. Auscultation can detect valve abnormalities and heart murmurs.

3. Use electrocardiography (ecg/ekg) to measure the electrical activity of the heart. ECGs provide detailed information about heart rhythm and conduction.

Electrical vs Mechanical Signals

• Procedure 1 measures arterial pulse - arterial response to the heart beating. This measures the rate not the specifics.

• Procedure 2 (stethoscope) measures the mechanical action behind the heart beating (more to come later). Detecting valve and other mechanical actions.

• Procedure 3 (ECG/EKG) measures the electrical activity of the heart. It picks up various electrical activities like depolorization and reploraztion.

Heart Beat Regulation

• 2 systems regulate heart activity:

1. Autonomic nervous system controls

2. Intrinsic Conduction System (or Nodal System) - Specialized cardiac cells that establish the heart rate. These cells generate electrical impulses that spread throughout the heart.

ECG Reading

• Electrical signal travels from the sinoatrial (SA) node through the atrium walls, causing contraction of the atria. The SA node is the heart's natural pacemaker.

• The signal pauses at the atrioventricular (AV) node, before traveling rapidly through the AV bundle, bundle branches, and Purkinje fibers in the ventricular wall, causing contraction of the ventricles. This coordinated electrical activity ensures efficient heart contraction.

Heart Beat Anatomy

• Stethoscope - measures the mechanical properties of a heart beat. it is a non-invasive tool for measuring heart beats.

• 2 distinct sounds: “lub” and “dup” lub dup pause, lub dup pause, etc.

• Cardiac Cycle - events of one complete heartbeat (60-100 bpm) This includes systole (contraction) and diastole (relaxation).

Heart Terms

• Systole - Contraction stages

• Diastole - Relaxation stages

• 5 events of the cardiac cycle (board diagram): Ventricular filling, atrial contraction, isovolumetric contraction, ventricular ejection, isovolumetric relaxation.

Heart Valve Sounds

• Heart sounds result