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DAT Kaplan > Bio: Endocrinology > Flashcards

Bio: Endocrinology Flashcards

1
Q

Endocrine system

A

Means of internal communication, coordinating the activities of organ systems.

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2
Q

What do endocrine glands make?

A

Synthesize and secrete chemical substances called hormones directly into the circulatory system

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3
Q

Hormones two major groups

A

Peptide hormones and steroid hormones

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4
Q

Peptide hormones

A

Range from simple short peptides (AA chains) such as ADH to complex polypeptides such as inuslin

short lived. surface reptors. act via secondary messengers

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5
Q

What happens when peptide hormones bind to specific extracellular receptors

A

By binding to specific extracellular receptors on the surface of their target cells, they trigger a series of enzymatic rxns within each cell.

EACH STARTS WITH ATP TO cAMP

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6
Q

Cyclic AMP

A

acts as a secondary messenger and relays messages from extracellular peptide hormone to cytoplasmic enzymes, initiating a cascade effect in which the hormone’s effects are catalyzed

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7
Q

What inactivates cAMP

A

cytoplasmic enzyme phosphodiesterase.

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8
Q

Steroid hormones

A

ie estrogen and aldosterone
Lipid derived molecules with ring structure.
Because they’re lipid soluble, steroid hormones enter their target cells directly and bind to specific INTRACELLULAR RECEPTOR PROTEINS in the cytoplasm.

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9
Q

Intracellular receptor + Steroid hormone complex

A

receptor-hormone complex enters nucleus and activates expression of specific genes by binding to receptors on chromatin..

Induces a change in mRNA transcription and protein synthesis

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10
Q

Endocrine glands (12)

A 
Pituitary
Hypothalamus
Thyroid
Parathyroids
Adrenals
Pancreas
Testes
Ovaries
Pineal
Kidneys
Gastrointestinal glands
Heart
Thymus
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11
Q

What determines the specificity of hormonal action

A

Presence of specific receptors on or in the target cells

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12
Q

Adrenal Glands

A

On top of kidneys.

Consist of adrenal cortex and adrenal medulla

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13
Q

Adrenal Cortex

A

With stress, ACTH stimulates adrenal cortexto synthesize and secrete the steroid hormones,, aka corticosteroids

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14
Q

Corticosteroids

A

Derived from cholesterol, includes glucocorticoids, mineralocorticoids, and cortical sex hormones

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15
Q

Glucocorticoids

A

Corticosteroids
Such as cortisol and cortisone
Involved in glucose regulation and protein metabolism.
Promote protein breakdown and use products in gluconeogenesis
Raise plasma glucose levels and are antagonistic to the effects of insulin

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16
Q

Mineralocorticoids

A

Particuarly aldosterone.

Regulate plasma levels of Na and K and the total extracellular water volume.

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17
Q

Aldosterone

A

Mineralocorticoid
Causes active reabsorption o sodium nd passive reabsorption of water in the nephron
Increases blood volume and blood pressure
Excess production of aldosterone = excess retention of water… HYPERTENSION

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18
Q

Cortical Sex hormones

A

Adrenal cortex secretes a little androgen (male sex hormone) in both M and F
androgen is made by testes.. physiologic effect of adrenal anrogens is small.
overproduction -> masculine

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19
Q

Adrenal Medulla

A 
Produces epinephrine (adrenaline) and norepinephrine (noradrenaline)
Both belong to AA derivedcopounds catecholaines
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20
Q

Epinephrine

A

Increase conversion of glycogen to glucose in liver and muscle tissue, causing a rise in blood glucose levels and basal metabolic rate.

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21
Q

Epinephrine and norepinephrine both do what?

A

increase the rate and strength of the heartbeatand they dilate and constrict blood vessels in a way as to increase blood supply sto skeletal muscle, heart, brain, while decreasing blood supply to kidneys, skin, and digestive tract

FIGHT OR FLIGHT

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22
Q

FIGHT OR FLIGHT

A

elicited by Sympathetic Nervous stimulation in response to stress
Epinephrine inhibits vegetative functions, like digestion.
both ep and norep are also NT

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23
Q

Control of adrenal hormones

A

Release of adrenal cortical hormones is controlled y ACTH

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24
Q

ACTH

A

hormone secreted by anterior pituitary gland
ACTH stimulates production of glucocorticoids and sex steroids.
Aldosterone production is controlled by reninangiotensin mechanism

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25
Q

Pituitary gland

A

small, tri-lobed gland lying at the base of the brain

Two main lobes, anterior and posterior are functionally distinct

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26
Q

Anterior Pituitary

A

synthesizes both direct hormones and tropic hormones

Regulated by hypothalamic secretions called releasing/inhibiting hormones or factors

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27
Q

Direct hormones

A

Directly stimulate their target organs

Growth hormones, prolactin, endorphins

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28
Q

Tropic hormones

A

Stimulate other endocrine glands to release hormones

ACTH, TSH, LH, FSH

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29
Q

Growth hormones

A

Direct hormone
GH, somatotropin
GH promotes bone and muscle growth. GH deficient = dwarf.
Overproduction = acromegaly

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30
Q

Prolactin

A

Direct hormone

Stimulate milk production and secretion in female mammary glands

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31
Q

Endorphins

A

Direct hormone

NT behaves like opioids providing and internal mechanism for pain relief and producing pleasure

32
Q

ACTH

A

Adrenocorticotropic hormone
Stimualtes adrenal cortex to synthesize and secrete glucocorticoids and Is regulated by releasing hormone corticotrophin-releasing factor CRF

33
Q

TSH

A

Thyroid stimulating hormone

Stimulates thyroid gland to synthesize and release thyroid hormones, thyroxine

34
Q

LH

A

Luteinizing hormone
F -> stimulate ovulation and formation of corpus luteum which secretes progesterone and estrogen
M-> stimulate interstitial cells of testes to synthesize testosterone

35
Q

FSH

A

Follicle stimulating hormone
F-> maturation of ovarian follicles, which secrete estrogen
M-> stimulates maturation of seminiferous tubules and sperm production

36
Q

Posterior pituitary

A

doesn’t synthesize hormones
Stores and releases peptide hormones oxytocin and ADH, which are produced by neurosecretory cells of hypothalamus
Secretion occurs when action potentials descend fro hypothalamus in response to body signals

37
Q

OXytocin

A

Posterior pituitary secretes
secreted during childbirth, increase strength and frequency of uterine muscle contractions. (+ feedback control) which releases more oxytocicn
Oxytocin secretion is induced by suckling, as it stimulates milk secretion in mammary glands

38
Q

ADH or vasopressin

A

Antidiuretic hormone
Posterior pituitary secretes
ADH increases permeability of collecting duct in nephron to water, promo of water reabsorption and decreasing blood osmolarity by increasing blood volume
Secreted when plasma orsmolarity increases, as sensed by osmoreceptors in hypothalamus or when blood volume decreases, as sensed by baroreceptors in circulatory system.

39
Q

Hypothalamus

A

in forebrain above pituitary gland
Receives NT from other parts of brain and peripheral nerves which trigger specific responses from its neurosecretory cells

40
Q

Neurosecretory cells

A

regulate pituitary gland secretions via negative feedback mechanisms and through actions if inhibiting and releasing hormones

41
Q

Interactions with Anterior Pituitary

A

hypothalamic releasing hormones stimulate or inhibit secretions of anterior pituitary
GnRH stimulates AP to secrete FSH and LH into hypothalamic hypophyseal portal system.
blood from capbed in hypothalamus flows through portal vein into AP, where it diverges into a second capillary network

42
Q

What happens when plasma levels of adrenal cortical hormones drop?

A

Hypothalamic cells relsease aCTH releasing factor (ACTH-RF) into the portal system.
If plasma concentration of corticosteroids&raquo_space; normal plasma level, steroids exert inhibitory effect on hypothalamus (- feedback)

43
Q

Interactions with Posterior Pituitary

A

Neurosecretory cells in hypothalamus synthesize both oxytocin and ADH and transport via axons into PP for storage and secretion

44
Q

Thyroid

A

bi-lobed structure located on the ventral surface of trachea. Produces and secretes thyroxine and triiodothyronine (thyroid hormones) and calcitonin

45
Q

Thyroid hormones

A

Thyroxine andtriiodothyronine
T4 and T3. derived from iodination of Tyrosine
Need for growth and neurological development in children. Also increase rate of metabolism throughout the body.

46
Q

Hypothyroidism

A

Thyroid hormones are undersecreted or not at all
Slowed heart rate and respiratory rate, fatigue, cold intolerance, weight gain. (in infants called creatinism) mental retardation and short stature.

Thyroid enlarges to bulge into a goiter

47
Q

Hyperthyroidism

A

Overstimulated thyroids
increased metabolic rate, feelings of excessive warmth, profuse sweating, palpitations, weight loss, protruding eyes.

Thyroid enlarges to bulge into a goiter

48
Q

Calcitonin

A

produced and secreted by Thyroid
Decreases plasma Ca2+ concentration by inhibiting release of Ca2+ from bone.
Calcitonin secretion is regulated by plasma Ca2+ levels
Antagonistic to parathyroid hormone.

49
Q

Pancreas

A

Exocrine and endocrine organ
Exocrine function: performed by cells that secrete digestive enzymes into the small intestines via series of ducts
Endocrine function: performed by small glandular structures called islets of Langerhans, which are composed of alpha and beta cells

50
Q

Alpha cells

A

produce and secrete glucagon

51
Q

Beta Cells

A

Produce and secrete insulin

52
Q

Glucagon

A

By alpha cells
Stimulates protein and fat degradation. Conversion of glycogen to glucose. Gluconeogensis.

All of these increase blood glucose levels.
Glucagon’s actions are largely antagonistic to those of insulin. Glucagon increases plasma glucose whereas insulin decreases it.

53
Q

Insulin

A

Protein hormone secreted by pancreas in response to a high blood glucose concentration.
It stimulates uptake of glucose by muscle and adipose cells and the storage of glucose as glycogen in muscle and liver cells. Lowers blood glucose levels.

Stimulates synthesis of fats and from glucose and uptake of AA
Insulin’s actions are antagonistic to those of glucagon and glucocorticoids.

54
Q

What else can increase plasma glucose?

A

GH Glucocorticoids, and epinephrine

55
Q

Diabetes mellitus

A

Underproductionof insulin, or insensitivity to insulin, leads to it.
Characterized by hyperglycemia (high blood glucose levels)

56
Q

Parathyroid glands

A

Four small, pea shaped structure in posterior surface of thyroid
Synthe and secrete parathyroid hormone, which regulates plasma Ca2+ concentration. PTH raises Ca2+ in blood by increasing bone resorption and deceasing Ca2+ excretion in kidneys.
PTH INCREASES Ca2+
Calcitonin decreases Ca2+

57
Q

What happens when calcium in the bone bonds to phosphate?

A

BD of bone releasing Phosphate and Calcium.

Parathyroid hormone compensates for this by stimulating excretion of phosphate by the kidneys.

58
Q

Kidneys

A

When blood volume decreases, kidneys make renin

59
Q

Renin

A

When blood volume decreases, kidneys make renin which converts plasma protein angiotensinogen to angiotensin I. Angiotensin I is converted to angiotensin II, which stimulates the adrenal cortex to secrete aldosterone. Aldosterone restores blood volume by increasing sodium reabsorption at the kidney, leading to an increase in water.

60
Q

Gastrointestinal hormones

A

ingested food stimulates stomach to release gastrin

61
Q

Gastrin

A

carried to gastric glands and stimulates glands to secrete HCl in response to food in stomach. Secretion of pancreatic juice, exocrine secretion of pancreas, is under hormone control. secretin.

62
Q

Secretin

A

released by small intestine when acidic food material enters the stomach.
stimulates secretion of alkaline bicarbonate solution from the pancrease, neutralizing chyme’s acidity

63
Q

Cholecystokinin

A

Released from small intestine in response to presence of fats and cause the contraction of the gallbladder and release of bile into small intestine.
Bile digests fats
Cholecystokinin can travel to brain’s satiation center to indicate being full

64
Q

Pineal gland

A

Tiny structure at the base of the brain that secretes melatonin.

65
Q

Melatonin

A

Regulates circadian rhythms, physiological cycles lasting 24 hours.
Melatonin secretion is regulated by light and dark cycles in environment.

66
Q

Plant hormones are primarily involved in the regulation o

A

Growth.
Produced by actively growing parts of the plant, such as the meristematic tissues in th eapical meristem offshoots and roots..
Also produced in young growing leaves and developing seeds

67
Q

Auxins

A

associated with phototropism and geotropism

68
Q

Phototropism

A

Tendency of shoots to bend to light.
light strikes tip of plant from a side, auxin supply on that side reduces.
illuminated side of the plant grows more slowly than the shaded side.
Asymmetrical growth in the cells of stem cause plant to bend toward light side.
Indoleacetic acid (auxin associated with phototropism)

69
Q

Geotropism

A

Growth of portions of plants towards or away from gravity
Negative -> cause shoots to grow up away from gravity. if a plant is on its side, the shoot witll eventually turn up.
Gravity increases concentration of auxin on lower side of horizontally plaed plant, while the concentration on the upper side decreases. Unnequal distribution of auxins stimulates cells on the lower side to elongate faster than cells on the upper side, grow up.

Positive: roots grow towards the pul of gravity. horizontally placed roots have same auxin distribution as horizontally placed stems, but effect on root ells is opposite.
Cells exposed to hi conc of auxin are inhibited from growing. cells with lower concentration continue to grow. roots turn down.

70
Q

Inhibition of lateral buds

A

auxins produced in terminal bud of aplant’s growing tip move downward in shoot and inhibit devo of lateral buds.
Auxins also initiate formation of lateral roots while inhibiting root elongation.

71
Q

Gibberellins

A

stimulate rapid stem elongation, particularly in plants that don’t grow tall.
inhibit formation of new roots
Stimulate production of new phloem by cambium (auxin stiulate production of new xylem)
Terminate dormancy of seeds and buds.
induce biennial plants to flower

72
Q

Kinins

A

promote cd
ratio of kkinetin to auxin is important in determining timing of differentiation of new cells. action of kinetin is enhanced with auxin

73
Q

Ethylene

A

induces senescence. aging

74
Q

Inhibitors

A

block cd and serve a role in growth regulation.
maintain dormancy in lateral buds and seeds of plants during autumn and winter. bd with time so that buds and seeds can be active in te growing season

Abscisic acid

75
Q

Anti auxins

A

regulate activity of auxins
Indoleacetic acid oxidase regulates conc of indoleacetic acids.
increase in oncentration of indoleacetic acid increases the amount of indoleacetic acid oxidase produced.

DAT Kaplan (3 decks)

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