Exam 4 Physiology (Ch.11-14)

What is a definition of a hormone?

regulatory molecule secreted into the blood by the endocrine gland

What is the difference between endocrine and exocrine glands?

Endocrine glands secrete hormones directly into the bloodstream, while exocrine glands secrete their products through ducts leading to the outside or a cavity within the body. Examples of endocrine glands include the thyroid and pituitary glands, while examples of exocrine glands include sweat and digestive glands. The pancreas is a unique gland that serves both endocrine and exocrine functions.

Why does the pancreas serve both roles?

The pancreas produces and secretes digestive enzymes and bicarbonate through a duct as an exocrine gland, and hormones like insulin and glucagon directly into the bloodstream as an endocrine gland.

What is the source of oxytocin?

hypothalamus

What is the target of oxytocin?

uterus and mammary glands

What is the effect of oxytocin?

stimulates contractions of uterus and mammary glands

What is the source of ADH?

hypothalamus

What is the target of ADH?

kidneys

What is the effect of ADH?

Regulates Water Retention or Elimination

What three commonalities are shared between all regulatory molecules?

1. Target cells must possess specific receptor for that molecule
2. Binding of regulatory molecule to its receptor must cause a change in that target cell's activity
3. A mechanism must be in place to turn off the action of the regulator or physiological control would be impossible

What is an example of a synergistic hormone interaction?

effect of epineohrine and norepinehphine on increasing heart rate

What is an example of an antagonistic interaction?

opposing effect of insulin and glucagon regarding blood sugar regulation

What is the mechanism of action for steroid hormones?

Hormone->travels through plasma membrane binding to receptors in cytoplasm-> travels to nucleus->binds to DNA->Binding activates hormone receptor complex->transcripition-> formation of mRNA-> leaves nucleus->directs protein synthesis-> produce hormonal effect

What is the ultimate intracellular(metabolic effect of the phosphlipase-C second messenger system?

It releases calcium ions from intracellular stores, activating various intracellular enzymes and pathways, leading to physiological responses such as muscle contraction, secretion, and gene expression.

What is the target of Adrenocoritecotropic Hormone (ACTH)?

adrenal cortex

What is the effect of Adrenocoritecotropic Hormone (ACTH)?

stimulates secretion of cortisol/stress response

What is the target of Thyroid stimulating hormone (TSH)?

Thyroid gland

What is the effect of Thyroid stimulating hormone (TSH)?

stimulates secretion of T3 and T4 regulating metabolism

What is the target of Growth hormone (GH)?

most body tissues

What is the effect of Growth hormone (GH)?

promotes the growth of bone and muscles

What is the target of Follicle stimulating hormone (FSH)?

gonadal tissues (ovaries and testis)

What is the effect of Follicle stimulating hormone (FSH)?

promote gamete production

What is the target of Prolactin (Prl)?

mammary glands

What is the effect of Prolactin (Prl)?

stimulates lactation

What is the target of Lutenizing hormone (LH)?

gonads

What is the effect of Lutenizing hormone (LH)?

stimulates ovulation / testosterone secretion

Where do releasing and inhibiting hormones come from and what (in general) do they do?

Releasing and inhibiting hormones are produced by specialized neruons in the hypothalamus of the brain and are released into the bloodstream through the capillary system. These cells act on specific cells in the anterior pituitary gland, regulating the secretion of hormones

What are the two negative feedback effects for both the sex steroids and thyroid hormone?

1. Inhibits the pituitarys response to thyrotropin-releasing hormone
2. inhibits the secretion of thryrotropin- releasing hormone from the hypothalamus in the first place

Under what circumstances are cortisol levels elevated?

Stress percieved by higher brain centers leads to the secretion of CRH from the hypothalamus. Increased releasing hormone leads to increased secretion of ACRH from the anterior pituitary gland and secretion of the stress hormone

What causes goiter?

iodine deficiency

What organ increases in size as a goiter develops?

enlargement of thyroid gland

What is the primary cause of cretinism?

Lack of dietry iodine

What do cretins suffer from?

stunted growth, intellectual disability, delayed motor development

What is Grave's disease?

An autoimmune disease of unknown etiology marked by diffused thyroid enlargement and excessive hormone secretion.

What is regulated by parathryoid hormone?

regulation of calcium and phosphorus levels in the body

What is secreted by the pineal gland?

melatonin

What is the functional role of this hormone of melatonin?

regulating sleep and wake cycle / circadian rhythm

How does the brain tell night from day when it is locked up in a dark box known as the skull?

pineal gland is stimulated by sympathetic axons in brainstem, regulated by the hypothalamus which recieves input from the retina

What is an orgin?

attachment of a muscle to an immovable bone

What is insertion?

attachment to movable bone

What are actions in muscle physiology?

movement caused when insertion is moved toward the orgin

The surface of the whole muscle is covered in an extension of the tendon which is __________

connective tissue

Bundle of muscle fibers is called _______

fascicle

What is the role of actin?

makes up microfilaments and thin filaments in myosin; most abundant protein in eukaryotic cell; has + and - side which allows for unidirectional movement

what is the role of myosin?

a protein that converts chemical energy in the form of ATP to mechanical energy, thus generating force and movement.

What is the role of titin?

-Holds the M-Line and Z-disc in place
-support protein

Describe in words the components of a neuromuscular junction and motor unit

Neuromuscular junction: point of connection between nerve and muscle fiber, components include presynaptic terminal, synaptic cleft, postsynaptic membrane, neurotransmitter (acetylcholine).
Motor unit: motor neuron and all muscle fibers it innervates, components include motor neuron, neuromuscular junction, muscle fibers, and motor end plate.

What two mechanisms contribute to the force of contraction?

1. Number of muscle cells in each motor unit
2. Number of motor units activated at one time / recruitment

What is summation?

multiple contractions are combined to produce a sustained muscle contraction

What is tetanus?

continuous contraction of a muscle fiber that occurs when it is stimulated repeatedly

What is fatigue?

muscle loses ability to maintain contraction

What is the role of creatine phosphate within muscle fibers?

providing energy for muscle contraction, rapidly generates ATP short term

What energy source is preferred by muscle fibers at rest?

fatty acids

What two energy sources are tapped into when muscle is hard at work?

1. Glycogen
2. Fatty acids;n slower atp than glycogen

What is the role of muscle spindle stretch receptors?

responsible for detecting changes in muscle length and the rate of change in muscle length. They play a critical role in the regulation of muscle tone and the coordination of movement.

What is the role of golgi tendon organs?

monitor muscle tension

Give an example of reciprocal innervation

Knee jerk reflex; hamstrings are relaxed, quads are contracted

What is hemiplegia?

paralysis of one side of the body

What is paraplegia?

paralysis of both lower limbs (lower spinal cord)

What is quadriplegia?

paralysis of all four limbs (higher spinal cord)

What is the primary function of blood?

To transport cells, nutrients, gases and dissolved matter through the body

What are the 4 systems linked to the circulatory system?

1. Digestive
2. Respiratory
3. Urinary
4. Endocrine

What is a hematocrit?

the ratio of the volume of red blood cells to the total volume of blood

What is the function of Albumin?

to maintain osmotic pressure which prevents plasma from leaking into tissues

What is the function of Globulin?

produce antibodies for immune system

What is the function of Fibrinogen?

blood clotting

General function of Red blood cells?

to transport oxygen from the lungs to the body's tissues and to transport carbon dioxide from the tissues back to the lungs to be exhaled.

General function of White blood cells?

protect the body against disease

General function of platelets?

blood clotting

What is hematopoiesis?

blood cell formation in red bone marrow

What does erythropoietin do?

stimulates RBC production

What is agglutination?

clumping of red blood cells

What is hemostasis?

stoppage of bleeding
1. collegen is exposed in blood vessels to platelets
2. Vasoconstriction
3. Platelet plug formation
4. Fibrin proteins form blood clots

General blood flow of the heart

What is the cardiac cycle?

The period from the end of one ventricular contraction to the end of the next ventricular contraction.

What is the cardiac cycles relationship to blood pressure?

complete sequence of events that occur during one heartbeat. It has a direct relationship with blood pressure, as the contraction of the heart during systole leads to an increase in blood pressure, while the relaxation of the heart during diastole leads to a decrease in blood pressure.

What is the pacemaker potential ?

slow, spontaneous depolarization of the membrane potential that occurs in cells of the sinoatrial (SA) node, the natural pacemaker of the heart. The pacemaker potential is driven by the opening of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which allow a small influx of positively charged ions (sodium and potassium) to depolarize the cell.

understand the role HCN channels and how they operate

The HCN channels play a critical role in the regulation of heart rate and rhythm, as they are responsible for the spontaneous depolarization that drives the SA node. Changes in the activity or expression of HCN channels can lead to alterations in heart rate and rhythm, and are associated with various cardiovascular diseases.

What does the "conducting system" of the heart refer to?

group of specialized cells that initiate and propagate electrical impulses throughout the heart, coordinating its contractions and maintaining its rhythmic beat. It includes the SA node, AV node, bundle of His, bundle branches, and Purkinje fibers, and is essential for proper cardiac function.

What is the functional unit of the circulatory system? why?

the capillary, which is the smallest and most numerous blood vessel in the body. This is because the capillaries are the site of exchange of nutrients, gases, and waste products between the blood and the body's tissues.

Why are venous valves necessary?

prevent the backflow of blood in the veins, which can occur due to the low pressure and slow flow of blood in these vessels. The valves act as one-way gates, allowing blood to flow towards the heart while preventing it from flowing backwards.

What is atheroclerosis?

clogging of the arteries with cholesterol

How does atherosclerosis contribute to heart attacks and strokes?

narrowing or blocking the arteries that supply blood to the heart and brain, respectively. This reduces blood flow and oxygen supply to these organs, leading to tissue damage and cell death, which can result in heart attacks or strokes.

What are the 3 functions of the lymphatic system?

1. It transports interstitial fluid back to the blood.
2.It transports absorbed fat from the intestines into the blood
3. The immune cells it produces, called lymphocytes, provide
defense against disease.

What is the Frank-Starling law of the heart?

the more the heart fills with blood during diastole, the greater the force of contraction during systole

During rest where is most of the blood found in the body?

found in the veins and venules, which hold about 60% of the total blood volume.

What is edema and what causes it?

large amounts of fluid in intercellular spaces, leading to tissue swelling

Can be caused by:
Decrease in plasma proteins
Retention of electrolytes, esp. Na+
Increase in capillary blood pressure

What is elephantiasis?

condition caused by Filarial worms that block the lymphatic vessels causing body parts to swell drastically

What is the function of Angiotensin II?

constrict arterioles and increase blood pressure

Where is blood pressure "lost" in the circulation?

as blood flows through the arterioles, capillaries, and venules, due to frictional resistance from the vessel walls and other factors. However, the majority of the pressure drop occurs across the arterioles, which have the highest resistance to blood flow, and is responsible for maintaining the pressure gradient that drives blood flow throughout the circulatory system.

What is myoglobin?

A protein that holds a reserve supply of oxygen in muscle cells

What gaseous neurotransmitter causes vasodilation in metabolically active organs such as skeletal muscles?

Nitric oxide (NO) is the gaseous neurotransmitter that causes vasodilation in metabolically active organs such as skeletal muscles.

What is being bypassed in a bypass surgery?

a new route for blood flow is created by grafting a blood vessel, typically from another part of the body, to bypass a blocked or narrowed coronary artery in the heart.

How does peripheral resistance affect blood pressure?

Increased peripheral resistance can raise blood pressure, while decreased peripheral resistance can lower blood pressure. Factors that can increase peripheral resistance include arterial constriction and plaque buildup, while factors that decrease peripheral resistance can help prevent high blood pressure.

Do baroreceptors regulate increases or decreases in blood pressure or both?

both increases and decreases in blood pressure by sending signals to the brainstem, which helps to decrease sympathetic nervous system activity and increase parasympathetic nervous system activity to lower blood pressure when it rises.

Korotkoff sounds

sounds heard while taking the blood pressure

What is the sound for systole?

lub

What is the sound for disastole?

dub

What are the dangers of hypertension?

1. Difficult for ventricles to eject blood against back pressure
2. Heart grows pathologically
3. Arrhythmias and valve problems leading to heart failure
4. Stroke and blown out cerebral arteries

how to calculate cardiac output

heart rate x stroke volume

How does negative feedback inhibition act on the thyroid system, and what is the resulting effect on thyroxine levels?

1. Elevated thyroxine levels in the blood inhibits the pituitary's response to thyrotropin-releasing hormone.
2. Elevated thyroxine levels in the blood inhibits the secretion of thyrotropin-releasing hormone from the hypothalamus in the first place.

What is the function of the pineal gland, and how is its secretion of melatonin regulated?

secretes the hormone melatonin, and its secretion follows a circadian or daily rhythm, tied to daily and seasonal changes in daylight. Melatonin secretion by the pineal gland begins to increase with darkness and peaks by the middle of the night when an individual should be sleeping.

What are the two functions of Golgi tendon organs, and how does their reflex pathway differ from a monosynaptic reflex?

they act as stretch receptors in tendons, and they prevent muscle damage by regulating muscle tension. Their reflex pathway differs from a monosynaptic reflex because it involves two synapses, one between the sensory neuron and the interneuron and the other between the interneuron and the motor neuron.

What are two features of the heart that enable it to meet its high oxygen demands, and how does it regulate blood flow during heavy exercise?

The heart's high oxygen demand is met by a large number of capillaries in the myocardium and myoglobin in heart muscle cells. During heavy exercise, the heart regulates blood flow by increasing the diameter of coronary arteries.