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Endocrine, Ch16 Flashcards

1
Q

Signals that use a hormone secreted by cells into the bloodstream to affect distant and different types of cells.

A

Endocrine signals

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2
Q

Signals where a chemical is secreted by specialized cells into the ECF to affect the same cell or a near one. Affects the same cell or cell type.

A

Autocrine signals

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3
Q

What is a primary endocrine organ vs secondary? What are the primary?

A

Primary has only endocrine functions, whereas secondary may have others. Anterior pituitary, thyroid, parathyroid, adrenal cortices, endocrine pancreas, thymus

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4
Q

Anatomically these structures consist of nervous tissue, yet they secrete chemicals that act as hormones, known as neurohormones. Examples?

A

Neuroendocrine glands, hypothalamus, pineal, adrenal medulla

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5
Q

Signals that consist of a chemical secreted by tissue cells into the ECF to affect nearby but different types of cells.

A

Paracrine signals

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6
Q

What are the signs and symptoms that accompany hormone secretion from cancer cells? What are the most common types of cells?

A

Paraneoplastic syndrome. Lung and gastrointestinal cancer cells

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7
Q

Where can hormone receptors for endocrine hormones reside?

A

Either in the plasma membrane or within the cytosol or nucleus of the target cell.

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8
Q

When the level of a particular hormone rises in the blood, certain target cells produce more of that hormone.
Prolonged exposure causes the opposite, with target cells decreasing the number of receptors.

A

Up-regulation. Down-regulation

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9
Q

Hormones that consist of one or more amino acids. Each type? Properties?

A

Amino acid-based hormone. Single amino is amine. Several is peptide. Complete proteins are protein hormones. Generally hydrophilic, except hydrophobic thyroid hormones

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10
Q

Hormones that are cholesterol derivatives, with a core of hydrocarbon rings. Properties?

A

Steroid hormones. Hydrophobic, can interact with either intracellular or plasma membrane receptors

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11
Q

What are the parts of a negative feedback loop?

A

Stimulus. Receptor. Control center (in endo system, the cell that detects a change in variable from normal is also generally control center). Effector/response. Homeostatic range

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12
Q

Hormones that control secretion from other endocrine glands.

Hormones that induce growth in their target cell.

A

Tropic hormone. Trophic hormone

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13
Q

What homeostatic functions is the hypothalamus involved in?

A

Regulation of hunger, thirst, fluid balance, body temp, sleep/wake cycle, and certain reproductive functions.

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14
Q

The small, anteroinferior portion of the diencephalon of the brain.

A

Hypothalamus

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15
Q

“Adeno” in adenohypophysis means gland, which reflects the fact that this is a true gland composed of hormone-secreting glandular epithelium.

A

Anterior pituitary gland

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16
Q

“Neuro” in neurohypophysis refers to the fact that this is actually made up of nervous tissue. It makes no hormones of its own, instead storing and releasing two neurohormones (?) that are produced by the hypothalamus.

A

Posterior pituitary gland. Antidiuretic hormone (ADH), vasopressin. Oxytocin

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17
Q

The tiny blood vessels called what merge in the hypothalamus to form larger blood vessels called what, which travel through the infundibulum? What is this system called?

A

Capillaries. Portal veins, which lead to a second group of capillaries in the anterior pituitary gland. Hypothalamic-hypophyseal portal system

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18
Q

In which capillaries are drained by veins that lead to another set of capillaries.

A

Portal systems

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19
Q

The hypothalamic hormone that controls water balance. Its primary function is to increase the amount of water retained by the kidneys, by causing the insertion of aquaporins into the kidney tubules. Net effect is to return water to the blood that would have otherwise been excreted through urine.

A

Antidiuretic hormone (ADH)/Vasopressin

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20
Q

Water channels in the plasma membranes of cells forming the kidney tubules. Allow water in the tubules to re-enter the cytosol of the kidney cells, reducing the amount of water in the tubules. From here, water moves into the ECF and blood by osmosis.

A

Aquaporins

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21
Q

Cells of the hypothalamus contain these, that monitor changes in the solute concentration of the blood. They respond to increasing solute by stimulating ADH release from the posterior pituitary, which leads to water retention, decreasing the concentration. And vice versa.

A

Osmoreceptors

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22
Q

An abnormal lack of ADH secretion or activity results in this disease. Symptoms include extreme thirst and signs of dehydration because the body is unable to conserve most of the water that is consumed.

A

Diabetes insidious. Treated by administration of synthetic ADH

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23
Q

A hormone produced by the hypothalamus whose functions are primarily reproductive. Primary target tissues are specialized cells of the mammary glands and the smooth muscle cells of the uterus. Release is triggered in nursing mothers by infant suckling.

A

Oxytocin

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24
Q

A positive feedback loop that occurs during infant suckling, when oxytocin binds to the specialized cells in the mammary glands stimulating their contraction, resulting in milk production.

A

Milk let-down reflex

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25
Q

The hypothalamus controls many of the functions of the anterior pituitary through the production and release of tropic hormones, called what 2 names? What system are these delivered to the anterior pituitary by?

A

Releasing and inhibiting hormones. Hypothalamic-hypophyseal portal system

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26
Q

What are the tiers of control in the negative feedback of the anterior pituitary hormones?

A

First: hypothalamus releases hormones. Second: anterior pituitary releases hormones. Third: target organs release hormones. Effects: hormone levels increase, effects on other cells, returns to normal range

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27
Q

What are the anterior pituitary hormones that affect other glands?

A

Thyroid-stimulating hormone (TSH). Adrenocorticotropic hormone (ACTH)/corticotropin. Prolactin. Luteinizing hormone (LH). Follicle-stimulating hormone (FSH)

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28
Q

What kind of cells produce and secrete TSH? What hypothalamic releasing hormone is its release triggered by? What is it inhibited by?

A

Thyrotrophs. Thyrotropin-releasing hormone. Somatostatin

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29
Q

What does ACTH do? What cells produce it? What is its release stimulated by?

A

Adrenocorticotropic hormone stimulates the development of the adrenal glands and their synthesis of various steroid hormones. It’s produced by corticotrophs. Stimulated by corticotropin-releasing hormone (CRH).

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30
Q

What is the primary target and purpose of the hormone prolactin?

A

Its primary target is mammary gland cells, where it stimulates the growth of the mammary gland, the initiation of milk production after childbirth, and the maintenance of milk production for the duration of breastfeeding.

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31
Q

What is the main stimulus for prolactin? What is it inhibited by?

A

Prolactin-releasing hormone (PRH), which is stimulated by suckling . Inhibited by prolactin-inhibiting factor, aka dopamine

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32
Q

Luteinizing hormone is one of two cells known as what? What is it stimulated by? What does it do in males and females?

A

Gonadotropin . Gonadotropin-releasing hormone (GnRH)

Males, stimulates production of testosterone. Females, estrogens and progesterone, release of oocytes

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33
Q

What is another gonadotropin that is stimulated by GnRH from the hypothalamus? What does it do in males and females?

A

Follicle-stimulating hormone (FSH)
In males, stimulates the cells of testes to produce chemicals that bind and concentrate testosterone. In females, FSH works with LH to trigger production of estrogens.

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34
Q

What hormone is produced and secreted by somatotrophs? When is the peak secretion for this hormone? What are its short-term effects?

A

Growth hormone, peaking during sleep. Primarily metabolic in nature, including promotion of fat breakdown (lipolysis), production of new glucose by the liver (glucogenisis), and inhibition of glucose uptake by muscle fibers.

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35
Q

What are the long-term effects of growth hormone?

A

GH acts on the liver and other target tissues to promote production of insulin-like growth factor (IGF). Triggers rapid protein synthesis and cell division, leading to increased longitudinal bone growth and muscle development in children. Decreases blood glucose concentration by stimulating glucose uptake by cells, opposite of acute GH release.

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36
Q

What two hormones regulate GH?

A

Growth hormone-releasing hormone (GHRH) stimulates the release of GH, increasing during exercise, fasting, stress, after a protein-rich meal.
Inhibited by somatostatin.

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37
Q

If GH hypersecretion occurs before closure of the epiphyseal plates, what is the resulting pathology? After close of the plates? Effects of both?

A

Gigantism. Skeleton and all other tissues increase in size, generally resulting in heart failure. Acromegaly. Longitudinal growth doesn’t take place, but tissues do increase in girth. Distorted facial features, thickening of the tongue and skin, enlargement of the hands and feet.

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38
Q

What does hyposecretion of GH prior to closure of the epiphyseal plates result in?

A

Pituitary dwarfism

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39
Q

The thyroid gland is composed of multiple spheres known as what? They are bounded by a layer of simple cuboidal epithelial cells known as what, which produce thyroid hormones?

A

Thyroid follicles. Follicle cells

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40
Q

The interior of a thyroid follicle is filled with what protein-rich gelatinous material, which is where the precursor of thyroid hormones is stored? It also contains a high concentration of iodine atoms, which are required for the hormone synthesis.

A

Colloid

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41
Q

Between the thyroid follicles lie clusters of these cells, which are larger than follicle cells. They play no role in thyroid hormone production, instead producing the hormone calcitonin.

A

Parafollicular cells

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42
Q

The hormone secreting cells of the parathyroid gland, which produce parathyroid hormone, are called what?

A

Chief cells

43
Q

Thyroid hormones consist of what? What are the two forms and which has greater physiological activity?

A

Amino acid core bound to iodine atoms. Triiodothyronine, with 3 iodine atoms (T3), more active. Thyroxine, with 4 iodine atoms (T4)

44
Q

Although T3 and T4 are amino acid-based hormones, what is different about them?

A

Their amino acids are nonpolar and hydrophobic, so they do not bind to cell-surface receptor proteins. Instead, they diffuse into cells and bind to intracellular receptors in the nucleus.

45
Q

What are the three main effects of the thyroid hormones?

A

Regulation of the metabolic rate and thermoregulation.
Promotion of growth and development.
Synergism with the sympathetic nervous system.

46
Q

What kind of hormones set the BMR? How?

A

Thyroid hormones. They increase the rate at which cells carry out catabolic and anabolic reactions, leading to no net change in the cell’s overall composition.
Na+/K+ pump function, gluconeogenisis, initiate energy-requiring reactions that build proteins and fats in same tissues. Maintains body temp.

47
Q

How do thyroid hormones help regulate blood pressure, heart rate, and other reactions of the SNS?

A

Increases in them act on target cells of the SNS and increase production of receptors for sympathetic neurotransmitters.

48
Q

What are the steps of thyroid hormone production?

A

Iodide ions and thyroglobulin are secreted into the colloid. Iodide ions are converted to iodine atoms that attach to thyroglobulin. Iodinated thyroglobulin enters the follicle cell by endocytosis and is converted to T3 and T4 by lysosomal enzymes. T3 and T4 are released into the blood.

49
Q

Which thyroid hormone is produced in greater amounts? Which has the longer half-life?

A

90% of the hormone produced is T4, and the remainder is T3. T3 has a half-life of about 2.5 days, and T4 about 6.5.

50
Q

What is the most common cause of hyperthyroidism, and how does it work? Why are symptoms?

A

Graves’ disease, which results when the immune system produces abnormal proteins that mimic the actions of TSH on the thyroid. This causes levels of T3 and T4 to increase. Symptoms include weight loss, heat intolerance, disruptions in heart rhythm, increase in blood pressure due to synergism of thyroid hormones with SNS.

51
Q

Name two signs of Graves’ disease and hyperthyroidism.

A

Exopthalamos, which involves bulging of the eyeballs due to weakening of the extraocular muscles and water retention in tissues around the orbits. Goiter, from swelling of the thyroid gland.

52
Q

What are the two most common causes of hypothyroidism? Signs and symptoms of it?

A

Iodine deficiency. Hashimoto’s thyroiditis, destruction of the thyroid gland by the immune system. Both of these cause decreased T3 and T4 production, concurrent increases in TRH and TSH. Symptoms are weight gain, cold intolerance, slow heart rate, low blood pressure due to decreased synergism with SNS.

53
Q

Why might a patient present with a goiter when diagnosed with hypothyroidism?

A

Hashimoto’s thyroiditis because the increased level of TSH promotes growth of the thyroid gland. Iodine deficiency because elevated level of TSH contributes, but also accumulation of thyroglobulin in the colloid of the follicles.

54
Q

What variant of hypothyroidism develops when an infant is born with inadequate thyroid function? What does it result in if left untreated?

A

Congenital hypothyroidism, cretinism. Delayed physical and nervous system development and eventual mental retardation.

55
Q

The chief cells of the parathyroid gland secrete what peptide hormone in response to declining blood calcium ion concentration? What is this decline called?

A

Paraythroid hormone (PTH). Hypocalcemia.

56
Q

What effects does PTH have on the body in order to raise blood calcium levels?

A

Increasing release of calcium ions from bone by stimulating osteoclasts. Increasing absorption of dietary calcium ions by the small intestine. Increasing reabsorption of calcium ions from the fluid in the kidneys through the tubules.

57
Q

How PTH increase absorption of calcium ions by the small intestine?

A

It acts on the kidneys to stimulate the conversion of vitamin D to its active form, D3/calcitriol. In this form, vitamin D3 increase the number of ions absorbed.

58
Q

What occurs when the blood calcium concentration raises above normal?

A

Hypercalcemia. The thyroid gland’s parafollicular cells release the hormone calcitonin, whose primary target are osteoclasts. It inhibits their activity, which allows osteoblasts to deposit calcium ions onto the bone.

59
Q

What are the two types of hormone produced by the adrenal glands?

A

Steroid hormones and catecholamines.

60
Q

In the adrenal gland, what portion is a typical endocrine gland and what portion is a neuroendocrine organ that secretes neurohormones?

A

The adrenal cortex is an endocrine gland.

The adrenal medulla is neuroendocrine.

61
Q

What are the three zones of the adrenal cortex and how are they arranged?

A

Outer zona glomerulosa, with densely packed cells. Middle zona fasciculata with cells stacked on top of one another in columns. Inner zona reticularis, thin and loosely arranged clusters.

62
Q

What types of steroid hormones derived from cholesterol does each zone of the adrenal cortex produce?

A

Zona glomerulosa produces mineralocorticoids. Zona fasciculata and reticularis produce glucocorticoids and androgenic steroids.

63
Q

Production of steroids by the adrenal cortex is partially regulated by a multi-tiered feedback system known as what?

A

Hypothalamic-pituitary-adrendocortical axis. HPA axis.

64
Q

What is the purpose of mineralocorticoids? What is the main mineralocorticoid and what does it do?

A

Regulating the concentration of minerals in the body. Aldosterone is the main one. It maintains the concentrations of extracellular sodium and potassium ions within normal ranges. Regulates the ECF volume. Maintains blood pressure and acid-base homeostasis.

65
Q

How does aldosterone help to maintain the concentrations of extracellular sodium and potassium ions?

A

Aldosterone acts on the cells of the kidney tubules. It stimulates transcription of more Na+/K+ pumps, sodium ion channels, and Na/Cl/K cotransporters. This causes Na and Cl to go from kidney tubules to ECF to the blood. K ions are transported from ECF into fluid in the kidney tubules where they are excreted in urine.

66
Q

How does aldosterone regulate ECF volume?

A

It creates a concentration gradient that favors movement of water by osmosis from fluid in tubule cells to the ECF and blood. It’s an indirect effect, it has no effect on the water molecules or water channels in the tubule cells.

67
Q

How does aldosterone maintain blood pressure? What larger system are these effects a part of, that involves the kidneys, lungs, and liver? What is its purpose?

A

When aldosterone indirectly promotes water reabsorption, this maintains ECF and blood volume, which maintains blood pressure. Renin-angiotensin-aldosterone system, RASS. Purpose is to increase blood pressure and preserve blood flow to the heart, brain, and kidneys.

68
Q

How does aldosterone work to maintain acid-base homeostasis?

A

It activates the hydrogen ion pumps in certain cells of the kidney tubules. These transport hydrogen ions from the ECF into the fluid of the tubules, after which they are excreted in the urine. pH of the blood stays slightly alkaline, at 7.35-7.45.

69
Q

What is the purpose of glucocorticoids? What is the most potent one in the body? What are its primary target tissues and effects?

A

They help mediate the body’s response to stress. Cortisol, or hydrocortisone, stimulates gluconeogenisis in the liver, release of amino acids from muscle tissue, and release of fatty acids from adipose tissue. It can also act as an anti-inflammatory agent by deceasing the levels of certain leukocytes.

70
Q

What are the two main causes of an excess of cortisol in the blood? What are the symptoms?

A

Oversecretion from the adrenal cortex, usually from a tumor, resulting in Cushing’s disease. Long-term administration of corticosteroids, producing iatrogenic Cushing’s syndrome, 90% of cases. Slim limbs, fat deposits in the midsection and into humped back, moon face. Muscle wasting due to release of amino acids, hyperglycemia. Renal retention of sodium ions and water, , suppression of immune response, bone loss, high blood pressure.

71
Q

Hyposecretion of both cortisol and aldosterone are hallmarks of what? What are some causes?

A

Adrenal insufficiency, or Addison’s disease. Abnormal development of the adrenal gland, deficiency in certain enzymes required to produce steroid hormones, destruction of adrenal glands by the immune system.

72
Q

What sex hormones that affect the gonads, reproductive organs, and other tissues are produced by the adrenal cortex, largely as a byproduct of what process?

A

Androgenic steroids, produced as a byproduct of the production of cortisol. Can be converted in the circulation into testosterone or estrogen.

73
Q

What cells derived from nervous tissue does the adrenal medulla consist of? What are they stimulated by?

A

Chromaffin cells, stimulated by Ach released by preganglionic neurons of the SNS. They are similar to postganglionic, except that they secrete their products into the bloodstream, earning them the name of neurohormones.

74
Q

What catecholamines are released by chromaffin cells? How do they mediate the body’s immediate response to a stressor?

A

Epinephrine (primarily) and norepinephrine. Increase rate and force of heart contraction, dilate bronchioles, constrict blood vessels supplying skin, digestive, and urinary. Dilate blood vessels supplying skeletal muscles, dilate pupils, decreasing digestive and urinary functions. Prolongs the duration of the sympathetic response.

75
Q

In what way is the pancreas both an endocrine and exocrine gland?

A

There are two groups of cells in the pancreas. Endocrine cells called pancreatic islets, or islets of Langerhans, which secrete into the bloodstream. Exocrine cells called acinar cells, which have ducts and secrete into the digestive tract.

76
Q

What are the three main pancreatic islet cell types and what do they each secrete?

A

Alpha cells, peptide hormone glucagon. Beta cells, protein hormone insulin. Delta cells, peptide hormone somatostatin.

77
Q

What are glucagon’a major target cells, and what reactions does it cause to increase glucose and metabolic fuels in the blood?

A

Liver, muscle, adipose. Glyconeogenisis, gluconeogenisis in the liver, protein breakdown in muscle to release amino acids and release of fats from adipose for gluconeogenisis, formation of ketones in the liver.

78
Q

What is glucagon secretion stimulated by? Inhibited by?

A

Stimulated by a decrease in blood glucose, stimulation from the SNS, and circulating catecholamines from the adrenal medulla. Inhibited by an elevated blood glucose level and somatostatin.

79
Q

What is the primary antagonist of glucagon? What is its main effect?

A

Insulin, which promotes the uptake and storage of ingested nutrients into its target cells, which lowers the level of glucose in the blood.

80
Q

What are insulin’s primary target tissues and its effects?

A

Liver, cardiac muscle, skeletal muscle, certain parts of the brain. Stimulates the uptake of lipids, amino acids, glucose. Synthesis of glycogen in the liver and fat from lipid and carbs. Promotion of satiety.

81
Q

What stimulates and inhibits insulin?

A

Stimulated by rising blood glucose concentrations. Inhibited by somatostatin and the SNS.

82
Q

When the insulin level rises too high, blood glucose level drops, a condition known as what? What are symptoms? Causes?

A

Hypoglycemia. Weakness, dizziness, rapid breathing, nausea, sweating. Severe can lead to confusion, hallucinations, seizures, coma, death. Most often caused my over administration of insulin or agents to lower blood glucose. Or prolonged starvation, tumors, alcohol, poisons, infection, metabolic disorders.

83
Q

Insufficient insulin secretion or decrease insulin sensitivity can cause blood glucose to become too elevated, a condition called what? Causes?

A

Hyperglycemia. Diabetes mellitus types 1 and 2.

84
Q

Which diabetes type is insulin-dependent? What is it caused by? Characterized by?

A

Type 1 diabetes mellitus. Cause by the destruction of the insulin-prosecuting beta cells of the pancreas by the immune system. Characterized by hyperglycemia.

85
Q

What type of diabetes is non-insulin dependent? What causes it?

A

Type 2 diabetes mellitus. The beta cells do not respond to normal increases in blood glucose, and other target cells are less responsive to insulin. Results in hyperglycemia and the accompanying signs and symptoms. Generally produces enough insulin to prevent ketoacidosis.

86
Q

What is the feedback loop when blood glucose level rises?

A

Blood glucose increases above normal range. Beta cells detect it, increasing insulin secretion while glucagon secretion from alpha cells are decreased. Insulin decreases the blood glucose level by increasing glucose uptake by cells and storage of glucose, amino acids, and fats. As blood glucose returns to normal, feedback to beta cells decreases insulin secretion.

87
Q

Explain the feedback loop when blood glucose level fall below the normal range?

A

Blood glucose decrease. Alpha cells detect it, and increase glucagon secretion while insulin secretion by beta cells falls. Glucagon increases blood glucose by triggering breakdown of glycogen into glucose and formation of new glucose. As return to normal happens, negative feedback decreases glucagon secretion.

88
Q

This gland is part of the epithalamus, which is the posterior portion of the diencephalon in the brain. What hormone does it secrete? What triggers its release? What are the targets?

A

Pineal gland, which secretes melatonin. Begins secretion when ambient light decreases in the evening, and reaches peak secretion during night hours. Targets are sleep-regulating centers in the reticular formation of the brainstem.

89
Q

What organ is found in the mediastinum? What is it the site for and what does it secrete?

A

Thymus. Site of maturation of leukocytes called T lymphocytes that are involved in immune response. Secretes hormones thymosin and thymopoietin, which function mainly as paraffins signals that assist in the maturation.

90
Q

What are the two types of effects testosterone has on its target cells?

A

Anabolic, which includes those that stimulate bone growth and muscle mass. Androgenic, which involves the development of male secondary sex characteristics.

91
Q

What protein hormone is produced by adipocytes? What are its target cells and effects?

A

Leptin, which acts on neurons in the hypothalamus that control feeding. Induces satiety, fullness.

92
Q

What hormone is secreted by cardiac muscle cells when blood volume inside the heart increases and the stretch-sensitive ion channels open more widely? Targets and effects?

A

Atrial natriuretic peptide (ANP). Smooth muscles cells lining blood vessels and tubules of the kidneys. Causes vasodilation as well as enhanced excretion of Na ions in the kidneys, natriuresis. This enhances water excretion. All of this causes decreased blood pressure.

93
Q

What hormone is secreted mainly by certain cells of the kidney in response to a decrease oxygen level in the blood? Effects?

A

Erythropoietin (EPO). Acts on red marrow, stimulating the development of erythrocytes, which increases oxygen-carrying capacity of the blood.

94
Q

What enzyme in the blood is secreted by kidney cells to convert the plasma protein angiotensinogen to angiotensin-I?

A

Renin

95
Q

What are the three main water regulating hormones?

A

ADH, aldosterone, and ANP.

96
Q

What happens in normal conditions to maintain fluid homeostasis?

A

Low levels of ADH and aldosterone are secreted continually and lead to average output. Huge volumes of blood are filtered through the kidneys every minute. These are secreted to ensure most of plasma volume is not lost to urine. Also electrolytes and acid-base.

97
Q

What happens to maintain fluid homeostasis when there is decreased plasma volume and increased solute concentration?

A

ADH and aldosterone secretion rise, leading to decreased urine output.

98
Q

What happens to main fluid homeostasis when there is increased plasma volume and decreased plasma solute concentration?

A

ADH and aldosterone secretions decline and ANP secretion increases, leading to increased urine output. This results in water loss from the blood and the increase in urine.

99
Q

How is metabolic homeostasis maintained at rest while fasting?

A

Thyroid hormones determine the BMR, triggering cells to consume ATP. They also stimulate gluconeogenisis, increasing blood glucose, helping maintain stable levels. Fasting also triggers the release of glucagon and GH, further raising blood glucose.

100
Q

How is metabolic homeostasis maintained at rest while feeding?

A

Insulin release is triggered, which triggers glucose uptake and storage of excess as glycogen and fat. Protein intake leads to GH and IGF-1 release, which triggers protein synthesis. Glucagon is release to prevent hypoglycemia. Lepton and insulin promote satiety.

101
Q

How is metabolic homeostasis maintained during exercise?

A

SNS increases catecholamine secretion from adrenal medulla, which causes the metabolic rate of all cells to increase to a higher level than that set by thyroid hormones. This means need of more fuels, which means alpha cells increase glucagon secretion.

102
Q

How does the adenylate cyclase-cAMP system work?

A

The G protein activates the enzyme adenylate cyclase. Adenylate cyclase catalyzes the formation of the 2nd messenger adenosine mono phosphate (cAMP) from the ATP. Cyclic AMP then initiates changes within the cell.

103
Q

Many of cAMP’s effects are due to the activation of enzymes called what?

A

Protein kinases which catalyze the transfer of a phosphate group from ATP to another molecule, phosphorylation.

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