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DAT Kaplan > Bio: Endocrinology > Flashcards

Bio: Endocrinology Flashcards

(75 cards)

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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
Pituitary gland
small, tri-lobed gland lying at the base of the brain | Two main lobes, anterior and posterior are functionally distinct
26
Anterior Pituitary
synthesizes both direct hormones and tropic hormones | Regulated by hypothalamic secretions called releasing/inhibiting hormones or factors
27
Direct hormones
Directly stimulate their target organs | Growth hormones, prolactin, endorphins
28
Tropic hormones
Stimulate other endocrine glands to release hormones | ACTH, TSH, LH, FSH
29
Growth hormones
Direct hormone GH, somatotropin GH promotes bone and muscle growth. GH deficient = dwarf. Overproduction = acromegaly
30
Prolactin
Direct hormone | Stimulate milk production and secretion in female mammary glands
31
Endorphins
Direct hormone | NT behaves like opioids providing and internal mechanism for pain relief and producing pleasure
32
ACTH
Adrenocorticotropic hormone Stimualtes adrenal cortex to synthesize and secrete glucocorticoids and Is regulated by releasing hormone corticotrophin-releasing factor CRF
33
TSH
Thyroid stimulating hormone | Stimulates thyroid gland to synthesize and release thyroid hormones, thyroxine
34
LH
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
FSH
Follicle stimulating hormone F-> maturation of ovarian follicles, which secrete estrogen M-> stimulates maturation of seminiferous tubules and sperm production
36
Posterior pituitary
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
OXytocin
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
ADH or vasopressin
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
Hypothalamus
in forebrain above pituitary gland Receives NT from other parts of brain and peripheral nerves which trigger specific responses from its neurosecretory cells
40
Neurosecretory cells
regulate pituitary gland secretions via negative feedback mechanisms and through actions if inhibiting and releasing hormones
41
Interactions with Anterior Pituitary
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
What happens when plasma levels of adrenal cortical hormones drop?
Hypothalamic cells relsease aCTH releasing factor (ACTH-RF) into the portal system. If plasma concentration of corticosteroids >> normal plasma level, steroids exert inhibitory effect on hypothalamus (- feedback)
43
Interactions with Posterior Pituitary
Neurosecretory cells in hypothalamus synthesize both oxytocin and ADH and transport via axons into PP for storage and secretion
44
Thyroid
bi-lobed structure located on the ventral surface of trachea. Produces and secretes thyroxine and triiodothyronine (thyroid hormones) and calcitonin
45
Thyroid hormones
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
Hypothyroidism
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
Hyperthyroidism
Overstimulated thyroids increased metabolic rate, feelings of excessive warmth, profuse sweating, palpitations, weight loss, protruding eyes. Thyroid enlarges to bulge into a goiter
48
Calcitonin
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
Pancreas
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
Alpha cells
produce and secrete glucagon
51
Beta Cells
Produce and secrete insulin
52
Glucagon
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
Insulin
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
What else can increase plasma glucose?
GH Glucocorticoids, and epinephrine
55
Diabetes mellitus
Underproductionof insulin, or insensitivity to insulin, leads to it. Characterized by hyperglycemia (high blood glucose levels)
56
Parathyroid glands
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
What happens when calcium in the bone bonds to phosphate?
BD of bone releasing Phosphate and Calcium. | Parathyroid hormone compensates for this by stimulating excretion of phosphate by the kidneys.
58
Kidneys
When blood volume decreases, kidneys make renin
59
Renin
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
Gastrointestinal hormones
ingested food stimulates stomach to release gastrin
61
Gastrin
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
Secretin
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
Cholecystokinin
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
Pineal gland
Tiny structure at the base of the brain that secretes melatonin.
65
Melatonin
Regulates circadian rhythms, physiological cycles lasting 24 hours. Melatonin secretion is regulated by light and dark cycles in environment.
66
Plant hormones are primarily involved in the regulation o
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
Auxins
associated with phototropism and geotropism
68
Phototropism
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
Geotropism
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
Inhibition of lateral buds
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
Gibberellins
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
Kinins
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
Ethylene
induces senescence. aging
74
Inhibitors
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
Anti auxins
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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