Chapter 6 - Endocrinology Flashcards

1
Q

chemical regulation in animals

endocrine system acts as a means of

A

internal communication

coordinates activities of organ systems

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2
Q

endocrine glands

A

synthesize and secrete hormones directly into circulatory system

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3
Q

hormones

A

chemical substances synthesized by endocrine glands

secreted directly into circulatory system

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4
Q

exocrine glands

A

e.g. gall bladder

secrete substances that are transported by ducts

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5
Q

glands that synthesize/secrete hormones

(13)

A

pituitary

hypothalamus

thyroid

parathyroids

adrenals

pancreas

testes

ovaries

pineal

kidneys

gastrointestinal

heart

thymus

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6
Q

hormones may regulate

A

single type of cell or organ

or

widespread actions

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7
Q

specificity of hormonal action usually determined by

A

presence of specific receptors on or in target cells

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8
Q

adrenal glands

structure

location

A

on top of kidneys

adrenal cortex + adrenal medulla

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9
Q

adrenal cortex

(makes up part of adrenal glands)

A

in response to stress, ACTH stimulates adrenal cortex to synthesize and secrete corticosteroids

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10
Q

ACTH

A

produced by anterior pituitary

stimulates adrenal cortex to synthesize and secrete cortiocosteroids

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11
Q

corticosteroids

A

steroids hormones

synthesized and secreted by adrenal cortex

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12
Q

corticosteroids

(3)

A

glucocorticoids

mineralocorticoids

cortical sex hormones

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13
Q

corticosteroids derived from

A

cholesterol

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14
Q

glucocorticoids

fxn

A

glucose regulation

protein metabolism

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15
Q

glucorticoids

examples (2)

A

cortisol

cortisone

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16
Q

glucocorticoids raise blood glucose levels by

A

promoting:

protein breakdown

gluconegenesis

decreasing:

protein synthesis

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17
Q

glucocorticoids and insulin

A

glucocorticoids raise plasma glucose levels

and are

antagonistic to effects of insulin

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18
Q

gluconegenesis

A

metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids

one of the two main mechanisms humans and many other animals use to keep blood glucose levels from dropping too low

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19
Q

two main mechanisms humans and many other animals use to keep blood glucose levels from dropping too low

A

gluconegenesis

glycogenolysis

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20
Q

mineralocorticoids

aldosterone

fxn

A

regulate plasma levels of sodium, potassium

consequently, total extracellular water volume

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21
Q

aldosterone

(mineralocorticoids)

A

causes active reabsorption of sodium and passive reabsorption of water in the nephron

—> rise in blood volume + blood pressure

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22
Q

nephron

A

basic structural and functional unit of the kidney

regulate concentration of water and soluble substances (sodium salts) by filtering the blood, reabsorbing what is needed and excreting the rest as urine

eliminates wastes from the body

regulates blood volume and blood pressure

controls levels of electrolytes and metabolites

regulates blood pH

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23
Q

excess production of aldosterone results in

A

excess retention of water

resulting hypertension (high blood pressure)

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24
Q

cortical sex hormones

A

adrenal cortex secretes small quantities of adrogens

(male and female)

small physiologic effect

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25
Q

adrogens

A

male sex hormones

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26
Q

adrogens secreted by adrenal cortex

A

adrostenedione

dehydroepiandrosterone

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27
Q

in males, most androgens produced by

A

testes

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28
Q

in females, overproduction of adrenal androgens may

A

have masculinizing effects

e.g. excessive facial hair

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29
Q

adrenal medulla

(adrenal gland)

A

produces epinephrine (adrenaline)

and norepinephrine (noradrenaline)

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30
Q

catecholamines

A

amino acid-derived compounds

includes:

norepinephrine

epinephrine

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31
Q

epinephrine

(adrenal medulla)

A

increases conversion of glycogen to glucose in liver and muscle tissue

causes rise in blood glucose —> increase in basal metabolic rate

type of catecholamine

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32
Q

both epinephrine and norepinephrine increase

A

rate and strength of heartbate

dilate and constrict blood vessels to incerase blood supply to skeletal muscle, heart, brain

decrease blood supply to kidneys, skin, digestive tract

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33
Q

fight or flight response

description

A

increase rate and strength of heartbeat

dilate, constrict blood vessels to:

increase blood supply to skeletal muscle, heart, brain

decrease blood supply to kidney, skin, digestive tract

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34
Q

fight or flight response elicited by

A

sympathetic nervous stimulation in response to stress

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35
Q

epinephrine inhibits

A

“vegetative” functions e.g. digestion

not immediately important for survival

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36
Q

epinephrine and norepinephrine

examples of

A

neurotransmitters

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37
Q

release of adrenal corticol hormones controlled by

A

adrenocorticotrophic hormone (ACTH)

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38
Q

adrenocorticotrophic hormone (ACTH) secreted by

A

anterior pituitary gland

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39
Q

adrenocorticotrophic hormone (ACTH) stimulates production of

A

glucocorticoids and sex steroids

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40
Q

Pituitary gland

(hypophysis)

structure

A

small, tri-lobed gland at base of brain

lobes - anterior, posterior, intermediate

(intermediate in humans - rudimentary)

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41
Q

anterior pituitary

fxn

(pituitary gland)

A

synthesizes direct hormones and tropic hormones

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42
Q

direct hormones

(synthesized by anterior pituitary)

A

directly stimulate target organs

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43
Q

tropic hormones

(anterior pituitary)

A

stimulate other endocrine glands to release hormones

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44
Q

hormonal secretions of anterior pituitary regulated by

A

hypothalamic secretions called releasing/inhibiting hormones or factors

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45
Q

hypothalamic secretions which regulate hormonal secretions of anterior pituitary are called

A

releasing/inhibiting hormones/factors

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46
Q

direct hormones

types

(anterior pituitary - synthesis of hormones)

A
  1. growth hormone
  2. prolactin
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47
Q

grwoth hormones (GH, somatotropin)

fxn

(direct hormones - anterior pituitary)

A

promotes bone and muscle growth

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48
Q

dwarfism caused by

(direct hormones - anterior pituitary)

A

GH deficiency in children

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49
Q

gigantism caused by

A

overproduction of GH in children

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50
Q

acromegaly caused by..

also, definition

(direct hormone - anterior pituitary)

A

overproduction of GH in adults

disproportionate overgrowth of bone

localized - skull, jaw, feet, hands

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51
Q

prolactin

(direct hormones - anterior pituitary)

A

stimulates milk production and secretion in female mammary glands

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52
Q

tropic hormones

types

(anterior pituitary - synthesis)

A
  1. adrenocorticotropic hormone (ACTH)
  2. thyroid-stimulating hormone (TSH)
  3. luteinizing hormone (LH)
  4. follicle-stimulating hormone (FSH)
  5. melanocyte-stimulating hormone (MSH)
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53
Q

FLAT PiG M

A

FSH

LH

ACTH

TSH

Prolactin

ignore

Growth hormone

MSH

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54
Q

adrenocorticotropic hormone

(ACTH)

(tropic hormone - anterior pituitary)

A

stimulate adrenal cortex to synthesize and secrete glucocorticoids

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55
Q

ACTH regulated by

A

releasing hormone corticotrophin releasing factor (CRF)

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56
Q

Thyroid-stimulating hormone (TSH)

A

stimulates thyroid gland to synthesize and release thyroid hormone

e..g thryoxin

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57
Q

luteinizing hormone (LH)

females

A

stimulates ovulation and formation of corpus luteum

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58
Q

luteinizing hormone (LH)

males

A

stimulates interstitial cells of testes to synthesize testosterone

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59
Q

follicle-stimulating hormone

(FSH)

females

A

causes maturation of ovarian follicles which begin secreting estrogen

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60
Q

follicle-stimulating hormone (FSH)

males

A

stimulates maturation of seminiferous tubules and sperm production

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61
Q

melanocyte-stimulating hormone (MSH)

A

secreted by intermediate lobe of pituitary

fxn in mammals unclear

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62
Q

melanocyte-stimulating hormone (MSH)

fxn in frogs

A

causes darkening of the skin via

induced dispersion of molecules of pigment in melanopore cells

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63
Q

posterior pituitary (neurohyphosis)

fxn

A

does NOT synthesize hormones

stores and releases peptide hormones: oxytocin and ADH

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64
Q

oxytocin and ADH produced by

A

neurosecretory cells of hypothalamus

65
Q

hormone secretion of posterior pituitary stimulated by

A

action potentials descending from hypothalamus

66
Q

oxytocin

A

secreted during childbirth

increases strength and frequency of uterine muscle contractions

also induced by suckling

sitmulates milk production in mammary glands

67
Q

antidiuretic hormone (ADH, vasopressin)

A

increases permeability of nephron’s collecting duct to water

promoting water reabsorption and increasing blood volume

68
Q

ADH secreted when..

A

plasma osmolarity increases

or

blood volume decreases

69
Q

plasma osmolarity changes sensed by

A

osmoreceptors in hypothalamus

70
Q

blood volume changes sensed by

A

baroreceptors in circulatory system

71
Q

hypothalamus

location

A

part of forebrain

directly above pituitary gland

72
Q

hypothalamus receives neural transmission from

A

other parts of the brain and peripheral nerves

that trigger responses from neurosecretory cells

73
Q

neurosecretory cells regulate

A

pituitary gland secretions

via negative feedback mechanisms, actions of inhibiting and releasing hormones

74
Q

hypothalamic releasing hormones stimulate or inhibit

A

secretions of anterior pituitar

75
Q

GnRH stimulates

A

the anterior pituitary to secrete FSH and LH

76
Q

releasing hormones are secreted into the

A

hypothalmic-hypophyseal portal system

(circulatory pathway)

77
Q

in the hypothalamic-hypophyseal portal system

A

blood from capillary bed in hypothalamus flows through portal vein into anterior pituitary

diverges into second capillary network

releasing hormones can immediately reach anterior pituitary

78
Q

secretions of endocrine system regulated by

A

feedback system

79
Q

regulation of plasma levels of adrenal cortical hormones

A

when plasma levels drop, hypothalamic cells (via negative feedback mech.) release ACTH-releasing factor (ACTH-RF) into portal system

when plasma conc of corticosteroids exceeds normal plasma level, steroids exert inhibitory effect on hypothalamus

80
Q

interactions of hypothalamus with posterior pituitary

A

neurosecretory cells in hypothalamus synthesize oxytocin and ADH and transport them via axons into posterior pituitary for storage and secretion

81
Q

thyroid

structure & location

A

bi-lobed

located on ventral surface of trachea

82
Q

thyroid produces and secretes

A

thyroid hormones (thyroxin, triiodothyronine)

calcetonin

83
Q

thyroid hormones

(thyroxine & triiodothyronine)

A

necessary for growth and development in children

increase rate of metabolism throughout body

84
Q

thyroxine (T4) and triiodothyronine (T3)

(thyroid hormones)

derived from

A

iodination of amino acid tyrosine

85
Q

hypothyroidism

cause

A

thyroid hormones undersecreted or not secreted at all

86
Q

symptoms of hypothyroidism

A

slowed heart rate, respiratory rate

fatige, cold intolerance, weight gain

87
Q

cretinism

A

hypothyroidism in newborn infants

characterized by mental retardation and short stature

88
Q

hyperthyroidism

definition

A

thyroid overstimulated —> oversecretion of thyroid hormones

89
Q

hyperthyroidism

symptoms

A

increased metabolic rate

excessive warmth, profuse sweating, palpiatations, weight loss, protruding eyes

90
Q

physical effect of hypo and hyperthyroidism

A

thyroid enlarges

forms bulge in neck: goiter

91
Q

calcitonin

A

produced and secreted by thyroid

decreases plasma Ca2+ concentration by inhibiting release of Ca2+ from bone

92
Q

calcitonin secretion regulated by

A

plasma Ca2+ levels

93
Q

calcitonin antagonistic to

A

parathyroid hormone

94
Q

pancreas

A

exocrine and endocrine organ

95
Q

exocrine function of pancreas performed by

A

cells that secrete digestive enzymes into small intestine via series of ducts

96
Q

endocrine function of pancreas performed by

A

small glandular structures - islets of Langerhaus

97
Q

islets of langerhans

A

performs endocrine function of pancreas

small glandular structure

composed of alpha and beta cells

98
Q

alpha cells produce and secrete

(islets of langerhans)

A

glucagon

99
Q

beta cells produce and secrete

(islets of langerhans)

A

insulin

100
Q

glucagon stimulates

A

protein and fat degradation

conversion of glyocgen to glucose

gluconeogenesis

101
Q

glucagon serves to

A

increase blood glucose levels

(plasma glucose)

102
Q

glucagon antagonistic to

A

insulin

103
Q

insulin secreted in response to

A

high blood glucose concentration

104
Q

insulin is a

A

protein hormone

105
Q

insulin stimulates uptake of glucose by

A

muscle and adipose cells

x

106
Q

insulin stimulates the stroage of glucose as

A

as glycogen in muscle and liver cells

107
Q

by stimulating the uptake and storage of glucose, insulin

A

lowers blood glucose levels

108
Q

insulin stimulates the synthesis of

A

fats from glucose and uptake of amino acids

109
Q

insulin antagonistic to

A

glucagon and glucocorticoids

110
Q

diabetes mellitus caused by

A

underproduction of insulin

insensitivity to insulin

111
Q

diabetes mellitus characterized by

A

hyperglycemia

112
Q

hyperglycemia

A

high blood glucose levels

(caused by diabetes)

113
Q

decrease plasma glucose

A
114
Q

increase plasma glucose

A

glucagon

growth hormone

glucocorticoids

epinephrine

115
Q

parathyroid glands

structure & location

A

four small pea-shaped

embedded in posterior surface of thyroid

116
Q

parathryoid glands synthesize and secrete

A

parathyroid hormone (PTH)

117
Q

parathyroid hormone (PTH)

A

regulates plasma Ca2+ concentration

raises Ca2+ by:

  1. increasing bone reabsorption
  2. decreases Ca2+ excretion in kidneys
118
Q

calcium in bone bonded to

A

phosphate

119
Q

breakdown of bone releases

A

phosphate + calcium

120
Q

parathyroid hormone compensates for breakdown of bone by

A

stimulating excretion of phosphate by kidneys

121
Q

kidneys

A

produce renin when blood volume falls

122
Q

renin

A

enzyme (produced by kidneys) that converts plasma protein angiotensinogen to angiotensin I

angitensin I converted to angiotensin II

angiotensin II stimulates adrenal cortex to secrete aldosterone

kidney –> renin –> angiotensinogen –> angiotensin I —> angiotensin II –> adrenal cortex secretes aldosterone

123
Q

aldosterone

A

restore blood volume by increasing sodium reabsorption at kidney —> increase in water

removes initial stimulus for renin production

124
Q

gastrointestinal hormones

A

ingested food stimulates stomach to release hormone gastrin

125
Q

mechanism initiated by gastrin

A

gastrin carried to gastric glands and stimulate release of HCl (in response to food in stomach)

126
Q

secretin released by

A

small intestine when acidic food enters from stomach

127
Q

secretin stimulates

A

secretion of alkaline bicarbonate solution from pancreas

128
Q

alkaline bicarbonate solution from pancreas

A

neutralizes acidity of chyme

129
Q

chyme

A

partially digested food coming from stomach

130
Q

cholecystokinin released from ___ in response to ____ and causes ____

A

small intestine;

fats;

contraction of gallbladder and release of bile into small intestine

131
Q

bile

A

involved in digestion of fats

released from gallbladder

132
Q

pineal gland

location

A

tiny structure at base of brain

133
Q

pineal gland secretes

A

melatonin

134
Q

melatonin role

A

role in humans unclear

role in regulation of circadian rhythms

135
Q

circadian rhythms

A

physiological cycles lasting 24 hours

136
Q

melatonin secretion regulated by

A

light and dark cycles in environment

137
Q

in primitive vertebrates, melatonin lightens the skin by

A

concentrating pigment granules in melanophores

138
Q

melatonin antagonist to

A
139
Q

hormones classified on basis of chemical structure into two major groups

A
  1. peptide hormones
  2. steroid hormones
140
Q

peptide hormones

structure

A

simple short peptides (amino acid chains)

e.g. ADH

to complex polypeptides

e.g. insulin

141
Q

peptide hormones act as

A

first messengers

142
Q

peptides trigger a series of enzymatic reactions within each cell by

A

binding to specific receptors on the surface of their target cells

143
Q

enzymatic reactions within target cell

(peptide hormones)

A
  1. conversion of ATP to cyclic adenosine monophosphate (cAMP)
144
Q

conversion of ATP to cyclic adenosine monophosphate (cAMP) catalyzed by

A

membrane-bound enzyme adenylate cyclase

145
Q

cyclic AMP acts as

A

second messenger

146
Q

cAMP acts as second messenger by relaying messages from

A

extracellular peptide hormone to cytoplasmic enzymes

initiating cascade

147
Q

cascade effect

A

initiate series of successive reactions in cell

with each step, hormones effects are amplified

148
Q

cAMP activity inactivated by

A

phosphodiesterase - a cytoplasmic enzyme

149
Q

steroid hormones

belong to class of

A

lipid-derived molecules with ring structure

e.g. estrogen, aldosterone

150
Q

steroids produced by

A

testes, ovaries, placenta, adrenal cortex

151
Q

steroid hormones enter their target cells ___ and bind to ____

A

directly;

specific receptor proteins in cytoplasm

152
Q

steroid hormones are able to enter target cells directly because they are

A

lipid soluble

153
Q

receptor hormone complex of steroid hormone and receptor protein in cytoplasm of target cell enters the

A

nucleus;

154
Q

once the steroid and receptor protein complex enters the nucleus, it directly activates

A

gene expression

155
Q

the protein receptor - steroid hormone complex directly activates gene expression by

A

binding to receptors on the chromatin

156
Q

the binding of the hormone-receptor complex to receptors on the chromatin induces ____

A

change in mRNA transcription and protein synthesis

157
Q

in short:

peptide hormones

A

surface receptors

generally act via secondary messengers

158
Q

in short:

steroid hormones

A

intracellular receptrors

hormone/receptor binding to DNA promotes transcription of specific genes

159
Q
A