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
2
Q
endocrine glands
A
synthesize and secrete hormones directly into circulatory system
3
Q
hormones
A
chemical substances synthesized by endocrine glands
secreted directly into circulatory system
4
Q
exocrine glands
A
e.g. gall bladder
secrete substances that are transported by ducts
5
Q
glands that synthesize/secrete hormones
(13)
A
pituitary
hypothalamus
thyroid
parathyroids
adrenals
pancreas
testes
ovaries
pineal
kidneys
gastrointestinal
heart
thymus
6
Q
hormones may regulate
A
single type of cell or organ
or
widespread actions
7
Q
specificity of hormonal action usually determined by
A
presence of specific receptors on or in target cells
8
Q
adrenal glands
structure
location
A
on top of kidneys
adrenal cortex + adrenal medulla
9
Q
adrenal cortex
(makes up part of adrenal glands)
A
in response to stress, ACTH stimulates adrenal cortex to synthesize and secrete corticosteroids
10
Q
ACTH
A
produced by anterior pituitary
stimulates adrenal cortex to synthesize and secrete cortiocosteroids
11
Q
corticosteroids
A
steroids hormones
synthesized and secreted by adrenal cortex
12
Q
corticosteroids
(3)
A
glucocorticoids
mineralocorticoids
cortical sex hormones
13
Q
corticosteroids derived from
A
cholesterol
14
Q
glucocorticoids
fxn
A
glucose regulation
protein metabolism
15
Q
glucorticoids
examples (2)
A
cortisol
cortisone
16
Q
glucocorticoids raise blood glucose levels by
A
promoting:
protein breakdown
gluconegenesis
decreasing:
protein synthesis
17
Q
glucocorticoids and insulin
A
glucocorticoids raise plasma glucose levels
and are
antagonistic to effects of insulin
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
19
Q
two main mechanisms humans and many other animals use to keep blood glucose levels from dropping too low
A
gluconegenesis
glycogenolysis
20
Q
mineralocorticoids
aldosterone
fxn
A
regulate plasma levels of sodium, potassium
consequently, total extracellular water volume
21
Q
aldosterone
(mineralocorticoids)
A
causes active reabsorption of sodium and passive reabsorption of water in the nephron
—> rise in blood volume + blood pressure
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
23
Q
excess production of aldosterone results in
A
excess retention of water
resulting hypertension (high blood pressure)
24
Q
cortical sex hormones
A
adrenal cortex secretes small quantities of adrogens
(male and female)
small physiologic effect
25
adrogens
male sex hormones
26
adrogens secreted by adrenal cortex
adrostenedione
dehydroepiandrosterone
27
in males, most androgens produced by
testes
28
in females, overproduction of adrenal androgens may
have masculinizing effects
e.g. excessive facial hair
29
adrenal medulla
| (adrenal gland)
produces epinephrine (adrenaline)
and norepinephrine (noradrenaline)
30
catecholamines
amino acid-derived compounds
includes:
norepinephrine
epinephrine
31
epinephrine
| (adrenal medulla)
increases conversion of glycogen to glucose in liver and muscle tissue
causes rise in blood glucose ---\> increase in basal metabolic rate
type of catecholamine
32
both epinephrine and norepinephrine increase
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
33
fight or flight response
description
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
34
fight or flight response elicited by
sympathetic nervous stimulation in response to stress
35
epinephrine inhibits
"vegetative" functions e.g. digestion
not immediately important for survival
36
epinephrine and norepinephrine
examples of
neurotransmitters
37
release of adrenal corticol hormones controlled by
adrenocorticotrophic hormone (ACTH)
38
adrenocorticotrophic hormone (ACTH) secreted by
anterior pituitary gland
39
adrenocorticotrophic hormone (ACTH) stimulates production of
glucocorticoids and sex steroids
40
Pituitary gland
(hypophysis)
structure
small, tri-lobed gland at base of brain
lobes - anterior, posterior, intermediate
(intermediate in humans - rudimentary)
41
anterior pituitary
fxn
(pituitary gland)
synthesizes direct hormones and tropic hormones
42
direct hormones
| (synthesized by anterior pituitary)
directly stimulate target organs
43
tropic hormones
| (anterior pituitary)
stimulate other endocrine glands to release hormones
44
hormonal secretions of anterior pituitary regulated by
hypothalamic secretions called releasing/inhibiting hormones or factors
45
hypothalamic secretions which regulate hormonal secretions of anterior pituitary are called
releasing/inhibiting hormones/factors
46
direct hormones
types
(anterior pituitary - synthesis of hormones)
1. growth hormone
2. prolactin
47
grwoth hormones (GH, somatotropin)
fxn
(direct hormones - anterior pituitary)
promotes bone and muscle growth
48
dwarfism caused by
(direct hormones - anterior pituitary)
GH deficiency in children
49
gigantism caused by
overproduction of GH in children
50
acromegaly caused by..
also, definition
(direct hormone - anterior pituitary)
overproduction of GH in adults
disproportionate overgrowth of bone
localized - skull, jaw, feet, hands
51
prolactin
(direct hormones - anterior pituitary)
stimulates milk production and secretion in female mammary glands
52
tropic hormones
types
(anterior pituitary - synthesis)
1. adrenocorticotropic hormone (ACTH)
2. thyroid-stimulating hormone (TSH)
3. luteinizing hormone (LH)
4. follicle-stimulating hormone (FSH)
5. melanocyte-stimulating hormone (MSH)
53
FLAT PiG M
FSH
LH
ACTH
TSH
Prolactin
ignore
Growth hormone
MSH
54
adrenocorticotropic hormone
(ACTH)
(tropic hormone - anterior pituitary)
stimulate adrenal cortex to synthesize and secrete glucocorticoids
55
ACTH regulated by
releasing hormone corticotrophin releasing factor (CRF)
56
Thyroid-stimulating hormone (TSH)
stimulates thyroid gland to synthesize and release thyroid hormone
e..g thryoxin
57
luteinizing hormone (LH)
females
stimulates ovulation and formation of corpus luteum
58
luteinizing hormone (LH)
males
stimulates interstitial cells of testes to synthesize testosterone
59
follicle-stimulating hormone
(FSH)
females
causes maturation of ovarian follicles which begin secreting estrogen
60
follicle-stimulating hormone (FSH)
males
stimulates maturation of seminiferous tubules and sperm production
61
melanocyte-stimulating hormone (MSH)
secreted by intermediate lobe of pituitary
fxn in mammals unclear
62
melanocyte-stimulating hormone (MSH)
fxn in frogs
causes darkening of the skin via
induced dispersion of molecules of pigment in melanopore cells
63
posterior pituitary (neurohyphosis)
fxn
does NOT synthesize hormones
stores and releases peptide hormones: oxytocin and ADH
64
oxytocin and ADH produced by
neurosecretory cells of hypothalamus
65
hormone secretion of posterior pituitary stimulated by
action potentials descending from hypothalamus
66
oxytocin
secreted during childbirth
increases strength and frequency of uterine muscle contractions
also induced by suckling
sitmulates milk production in mammary glands
67
antidiuretic hormone (ADH, vasopressin)
increases permeability of nephron's collecting duct to water
promoting water reabsorption and increasing blood volume
68
ADH secreted when..
plasma osmolarity increases
or
blood volume decreases
69
plasma osmolarity changes sensed by
osmoreceptors in hypothalamus
70
blood volume changes sensed by
baroreceptors in circulatory system
71
hypothalamus
location
part of forebrain
directly above pituitary gland
72
hypothalamus receives neural transmission from
other parts of the brain and peripheral nerves
that trigger responses from neurosecretory cells
73
neurosecretory cells regulate
pituitary gland secretions
via negative feedback mechanisms, actions of inhibiting and releasing hormones
74
hypothalamic releasing hormones stimulate or inhibit
secretions of anterior pituitar
75
GnRH stimulates
the anterior pituitary to secrete FSH and LH
76
releasing hormones are secreted into the
hypothalmic-hypophyseal portal system
(circulatory pathway)
77
in the hypothalamic-hypophyseal portal system
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
secretions of endocrine system regulated by
feedback system
79
regulation of plasma levels of adrenal cortical hormones
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
interactions of hypothalamus with posterior pituitary
neurosecretory cells in hypothalamus synthesize oxytocin and ADH and transport them via axons into posterior pituitary for storage and secretion
81
thyroid
structure & location
bi-lobed
located on ventral surface of trachea
82
thyroid produces and secretes
thyroid hormones (thyroxin, triiodothyronine)
calcetonin
83
thyroid hormones
| (thyroxine & triiodothyronine)
necessary for growth and development in children
increase rate of metabolism throughout body
84
thyroxine (T4) and triiodothyronine (T3)
(thyroid hormones)
derived from
iodination of amino acid tyrosine
85
hypothyroidism
cause
thyroid hormones undersecreted or not secreted at all
86
symptoms of hypothyroidism
slowed heart rate, respiratory rate
fatige, cold intolerance, weight gain
87
cretinism
hypothyroidism in newborn infants
characterized by mental retardation and short stature
88
hyperthyroidism
definition
thyroid overstimulated ---\> oversecretion of thyroid hormones
89
hyperthyroidism
symptoms
increased metabolic rate
excessive warmth, profuse sweating, palpiatations, weight loss, protruding eyes
90
physical effect of hypo and hyperthyroidism
thyroid enlarges
forms bulge in neck: goiter
91
calcitonin
produced and secreted by thyroid
decreases plasma Ca2+ concentration by inhibiting release of Ca2+ from bone
92
calcitonin secretion regulated by
plasma Ca2+ levels
93
calcitonin antagonistic to
parathyroid hormone
94
pancreas
exocrine and endocrine organ
95
exocrine function of pancreas performed by
cells that secrete digestive enzymes into small intestine via series of ducts
96
endocrine function of pancreas performed by
small glandular structures - islets of Langerhaus
97
islets of langerhans
performs endocrine function of pancreas
small glandular structure
composed of alpha and beta cells
98
alpha cells produce and secrete
| (islets of langerhans)
glucagon
99
beta cells produce and secrete
| (islets of langerhans)
insulin
100
glucagon stimulates
protein and fat degradation
conversion of glyocgen to glucose
gluconeogenesis
101
glucagon serves to
increase blood glucose levels
| (plasma glucose)
102
glucagon antagonistic to
insulin
103
insulin secreted in response to
high blood glucose concentration
104
insulin is a
protein hormone
105
insulin stimulates uptake of glucose by
muscle and adipose cells
x
106
insulin stimulates the stroage of glucose as
as glycogen in muscle and liver cells
107
by stimulating the uptake and storage of glucose, insulin
lowers blood glucose levels
108
insulin stimulates the synthesis of
fats from glucose and uptake of amino acids
109
insulin antagonistic to
glucagon and glucocorticoids
110
diabetes mellitus caused by
underproduction of insulin
insensitivity to insulin
111
diabetes mellitus characterized by
hyperglycemia
112
hyperglycemia
high blood glucose levels
| (caused by diabetes)
113
decrease plasma glucose
114
increase plasma glucose
glucagon
growth hormone
glucocorticoids
epinephrine
115
parathyroid glands
structure & location
four small pea-shaped
embedded in posterior surface of thyroid
116
parathryoid glands synthesize and secrete
parathyroid hormone (PTH)
117
parathyroid hormone (PTH)
regulates plasma Ca2+ concentration
raises Ca2+ by:
1. increasing bone reabsorption
2. decreases Ca2+ excretion in kidneys
118
calcium in bone bonded to
phosphate
119
breakdown of bone releases
phosphate + calcium
120
parathyroid hormone compensates for breakdown of bone by
stimulating excretion of phosphate by kidneys
121
kidneys
produce renin when blood volume falls
122
renin
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
aldosterone
restore blood volume by increasing sodium reabsorption at kidney ---\> increase in water
removes initial stimulus for renin production
124
gastrointestinal hormones
ingested food stimulates stomach to release hormone gastrin
125
mechanism initiated by gastrin
gastrin carried to gastric glands and stimulate release of HCl (in response to food in stomach)
126
secretin released by
small intestine when acidic food enters from stomach
127
secretin stimulates
secretion of alkaline bicarbonate solution from pancreas
128
alkaline bicarbonate solution from pancreas
neutralizes acidity of chyme
129
chyme
partially digested food coming from stomach
130
cholecystokinin released from \_\_\_ in response to ____ and causes \_\_\_\_
small intestine;
fats;
contraction of gallbladder and release of bile into small intestine
131
bile
involved in digestion of fats
released from gallbladder
132
pineal gland
location
tiny structure at base of brain
133
pineal gland secretes
melatonin
134
melatonin role
role in humans unclear
role in regulation of circadian rhythms
135
circadian rhythms
physiological cycles lasting 24 hours
136
melatonin secretion regulated by
light and dark cycles in environment
137
in primitive vertebrates, melatonin lightens the skin by
concentrating pigment granules in melanophores
138
melatonin antagonist to
139
hormones classified on basis of chemical structure into two major groups
1. peptide hormones
2. steroid hormones
140
peptide hormones
structure
simple short peptides (amino acid chains)
e.g. ADH
to complex polypeptides
e.g. insulin
141
peptide hormones act as
first messengers
142
peptides trigger a series of enzymatic reactions within each cell by
binding to specific receptors on the surface of their target cells
143
enzymatic reactions within target cell
(peptide hormones)
1. conversion of ATP to cyclic adenosine monophosphate (cAMP)
144
conversion of ATP to cyclic adenosine monophosphate (cAMP) catalyzed by
membrane-bound enzyme adenylate cyclase
145
cyclic AMP acts as
second messenger
146
cAMP acts as second messenger by relaying messages from
extracellular peptide hormone to cytoplasmic enzymes
initiating cascade
147
cascade effect
initiate series of successive reactions in cell
with each step, hormones effects are amplified
148
cAMP activity inactivated by
phosphodiesterase - a cytoplasmic enzyme
149
steroid hormones
belong to class of
lipid-derived molecules with ring structure
e.g. estrogen, aldosterone
150
steroids produced by
testes, ovaries, placenta, adrenal cortex
151
steroid hormones enter their target cells ___ and bind to \_\_\_\_
directly;
specific receptor proteins in cytoplasm
152
steroid hormones are able to enter target cells directly because they are
lipid soluble
153
receptor hormone complex of steroid hormone and receptor protein in cytoplasm of target cell enters the
nucleus;
154
once the steroid and receptor protein complex enters the nucleus, it directly activates
gene expression
155
the protein receptor - steroid hormone complex directly activates gene expression by
binding to receptors on the chromatin
156
the binding of the hormone-receptor complex to receptors on the chromatin induces \_\_\_\_
change in mRNA transcription and protein synthesis
157
in short:
peptide hormones
surface receptors
generally act via secondary messengers
158
in short:
steroid hormones
intracellular receptrors
hormone/receptor binding to DNA promotes transcription of specific genes
159
