CHAPTER 11: ENDOCRINE Flashcards
1
Q
endocrine glands
A
ductless organs or groups of cells that secrete hormones directly into the blood or other bodily fluids
2
Q
three major structural classes of hormones:
A
1) amines
2) peptides & proteins
3) steriods
3
Q
amine hormones
A
derivatives of amino acid tyrosine: examples are epinephrine, norepinephrine, dopamine
4
Q
how many adrenal glands?
A
2 (one above each kidney)
5
Q
adrenal medulla
A
-located in each adrenal gland, secretes catecholamines (norepinephrine + epinephrine) into BLOOD
-cell bodies do not have axons
6
Q
adrenal cortex
A
secretes steroid hormones
7
Q
dopamine is released into a special circulatory system called:
A
portal system (which carries it to pituitary gland)
8
Q
peptide hormones are synthesized as large molecules called _____ which are then cleaved to _____ by proteolytic enzymes in rough ER
A
preprohormones, prohormones
9
Q
post-translational modification
A
prohormone packaged into secretory vesicles by golgi apparatus and then is cleaved to yield active hormone and other peptide chains
10
Q
peptide hormone processing
A
synthesis: preprohormone –> prohormone
packaging: prohormone –> hormone
storage: hormone stored in secretory vesicles
secretion: hormone is secreted via exocytosis
11
Q
vitamin ___ is enzymatically converted in the body to an active steroid hormone
A
vitamin D
12
Q
five major hormones secreted from adrenal cortex
A
-corticosterone
-aidosterone
-cortisol
-androstendione
-dehydroepiandrosterone
13
Q
mineralocorticoid
A
hormone that effects salt mineral balance (ex: aldosterone)
14
Q
aldosterone characteristics
A
-it is a mineralocorticoid
-stimulates the kidneys to retain sodium
-it is derived from cholesterol.
-it stimulates the kidneys to excrete potassium in the urine
15
Q
angiotensin II
A
control production of aldosterone & binds to plasma membrane receptors in adrenal cortex to activate a second messenger pathway
16
Q
glucocorticoids
A
steroids that affect metabolism of glucose + other organic nutrients (ex: cortisol)
17
Q
androgens
A
group of steroid hormones (sex hormones such as testosterone)
18
Q
three laters of adrenal cortex (outer to inner)
A
zona glomerulosa
zona fasciculata
zona reticularis
19
Q
zona glomerulosa
A
outermost layer of AC that expresses enzymes required to synthesize corticosterone and convert it to aldosterone
20
Q
zona fasciculata
A
middle layer of AC that produces cortisol
21
Q
zona reticularis
A
inner layer of AC that produces androgens
22
Q
medulla produces…
A
epinephrine and norepinephrine
23
Q
congenital adrenal hyperplasia
A
excess adrenal androgen production results in virilization of female genitalia
24
Q
estrogens
A
ovarian endocrine cells that synthesize female sex hormones
25
_______ is the predominant estrogen present during a woman's lifetime
estradiol
26
progesterone
steroid important for maintaining a pregnancy, secreted by endocrine cells of the corpus luteum
27
hormone equilibrium equation
free hormone + binding protein ⇌ hormone - protein complex
28
peptide hormones & catecholamines VS. steroids & thyroid hormones
peptide hormones & catecholamines are SOLUBLE IN PLASMA and steroids & thyroid hormones are POORLY SOLUBLE (b/c they circulate bound to plasma proteins)
29
hormones [ ] in the plasma depends on:
-rate of secretion of endocrine gland
-rate of removal from the blood
30
basal levels of cortisol helps maintain what?
blood pressure
31
cortisol is important for maintaining [ ]s of _____ that are in the ______ that act to increase ______, which prevents plasma glucose levels from dropping below normal
cortisol is important for maintaining [ ]s of certain enzymes that are in the liver that act to increase hepatic glucose production, which prevents plasma glucose levels from dropping below normal
32
cortisol: ____
epinephrine: ____
cortisol: adrenal cortex
epinephrine: adrenal medulla
33
example of how metabolism of a hormone activates the hormone rather than inactivates it
t4 produced by thyroid gland is converted to much more active t3 inside target cell
34
receptors for water-soluble chemical messengers are proteins located in _____
plasma membranes of target cells
35
up-regulation
an increase in number of a hormone's receptors in a cell as a result of prolonged exposure to a low [ ] of it
36
down-regulation
a decrease in receptor number, often from exposure to high [ ]s of hormone --> prevents overtstimulation
37
permissiveness
hormone A must be present in order for hormone B to exert its full effect
*could be due to A's ability to up-regulate B's receptors
38
CC thyroid hormone and epinephrine
thyroid = little to no fatty acids released
epinephrine = small amount of fatty acids released
epinephrine + TH = large amount of fatty acids released
39
example of a pharmacological effect of hormones
very potent synthetic forms of cortisol are administered to suppress allergic and inflammatory reactions
40
hormone secretion is controlled by:
-changes in plasma [ ]s of mineral ions or organic nutrients
-neurotransmitters released from neurons ending on endocrine cell
-another hormone acting on endocrine cell
41
secretion (of hormone):
release by exocytosis from the cell
42
_____ nervous system controls secretion of hormones
autonomic (neurons of symp and parasymp regulate secretion)
43
tropic hormone
a hormone that stimulates the secretion of another hormone (as well as growth of the stimulated gland)
44
anterior pituitary gland
(anterior lobe) arises embryologically from invagination
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posterior pituitary gland
(posterior lobe) an extension of the neural components of the hypothalamus
46
median eminence
junction of hypothalamus and infundibulum
47
hypothalamo-hypophyseal portal vessels (portal veins)
capillaries in median eminence recombine to form this
48
two posterior pituitary hormones (released by axons with cell bodies)
oxytocin and vasopressin (peptides)
49
role of oxytocin
-stimulates contraction of smooth muscle cells in breasts (--> milk ejection/lactation)
-released when stretch receptors in cervix send neural signals back to hypothalamus during labor
50
role of vasopressin
-stimulates contraction of smooth muscle cells around blood vessels
-acts within kidneys to decrease water excretion in the urine (maintain blood volume)
51
vasopressin is also known as:
antidiuretic hormone (ADH)
52
hypophysiotropic hormones
hormones from hypothalamus that regulate anterior pituitary gland function
53
what are the six hormones that the ant. pit. gland secretes?
1) follicle-stimulating hormone (FSH)
2) luteinizing hormone (LH)
3) growth hormone (GH)
4) thyroid-stimulating hormone (TSH)
5) prolactin
6) adrenocorticotropic hormone (ACTH)
54
which two hormones stimulate gonads and are termed "gonadotropic hormones"?
FSH and LH
55
two peptides derived from ACTH
beta-lipotropin and beta-endorphin
56
insulin-like growth factor-1 (IGF-1) hormone
growth-promoting peptide hormone secreted by growth hormone
57
secretion of ACTH is stimulated by...
corticotropin-releasing hormone (CRH)
58
secretion of growth hormone is stimulated by...
growth hormone-releasing hormone (GHRH)
59
secretion of thyroid-stimulating hormone is stimulated by...
thyrotropin-releasing hormone (TRH)
60
secretion of both LH and FSH is stimulated by...
gonadotropin-releasing hormone (GnRH)
61
two hormones that inhibit the release of an ant. pit. gland hormone
somatostatin (SST) and dopamine (DA)
62
______ ______ is a key component of most homeostatic control systems because it can limit extremes of hormone secretory rates
negative feedback (ex: cortisol)
63
long-loop negative feedback
a situation where, for example, the cortisol secreted by third endocrine gland in a sequence exerts negative feedback effect over ant. pit./hypothalamus
64
short-loop negative feedback
influence of an ant. pit. gland hormone on the hypothalamus
65
what two iodine-containing molecules does the thyroid gland produce?
thyroxine (T4) --> main secretory product and triiodothyronine (T3) --> active hormone
66
follicles
small, fluid-filled sacs found in the ovaries that contain immature eggs located within thyroid gland
67
colloid
protein-rich material in the core surrounded by epithelial cells
68
iodide trapping
process where circulating iodide is actively cotransported with sodium ions across the basolateral membranes of epithelial cells
69
pendrin
integral membrane protein + sodium-independent chloride/iodide transporter
70
thyroglobulin
protein that colloid of follicles contains
71
organification of iodine
iodine is rapidly oxidized at luminal surface of follicular epithelial cells in colloid - then attached to phenolic rings of tyrosine residues
72
thyroid peroxidase
enzyme responsible for oxidizing iodides and attaching them to tyrosines on thyroglobulin in colloid
73
tyrosine with one iodine attached =
monoiodotyrosine (MIT) & two iodines - diiodotyrosine (DIT)
74
steps involved in T3 and T4 formation:
1) iodide is cotransported with Na+ across basolateral membranes
2) iodide ions diffuse to apical membrane and are transported into colloid
3) iodide is oxidized at luminal surface and is attached to phenolic rings of tyrosine residues (organification)
4) iodinated ring of one MIT or DIT is added to a DIT on thyroglobulin molecule
5) endocytosis of thyroglobulin containing T3 and T4 molecules
6) thyroglobulin is brought into contact with lysosomes in cell interior
7) release of T3 and T4 + diffusion out of follicular epithelial cell into interstitial fluid
75
hypertrophy
when thyroid cells are exposed to greater TSH concentrations than normal and INCREASE IN SIZE
76
goiter
enlarged thyroid gland from any cause
77
thyroid hormone increases metabolic rate because...
...it decreases cellular stores of ATP and increases glycolysis (negative feedback)
and in turn increases heat production
78
thyroid hormone increases effectiveness of actions of the _______
sympathetic nervous system
79
congenital hypothyroidism
syndrome characterized by poorly developed nervous system and compromised intellectual function as a result of NO T3 hormone
80
hypothyroidism
plasma concentrations of thyroid hormones are chronically below normal
+ increased sensitivity to cold and tendency towards weight gain
81
for hypothyroidism, do TRH levels increase or decrease?
increase because ant.pit must release more TSH to stimulate the thyroid gland to produce more hormone
82
autoimmune thyroiditis (can result from hashimoto's)
autoimmune disruption of normal function of thyroid gland (hypothyroidism)
83
hyperthyroidism
characterized by the production of antibodies that bind to and activate the TSH receptors on thyroid gland cells --> chronic overstimulation of them (grave's)
+ heat intolerance, weight loss
84
sequence CRH-ACTH-cortisol pathway
neural inputs (stress)
->
hypothalamus secrets CRH
-->
plasma CRH
-->
reaches ant. pit. which secretes ACTH
-->
plasma ACTH
-->
reaches adrenal cortex which stimulates cortisol release
-->
plasma cortisol (cells respond to increase in cortisol)
85
role of cortisol
-maintains normal BP
-maintains concentrations of certain enzymes involved in metabolic homeostasis
-inhibits production of things involved in inflammation
-supresses growth and function of certain key immune cells such as lymphocytes
-*important developmental hormone*
-makes it easier for lungs to inflate
86
87
increased cortisol medaites:
gluconeogenesis, lipolysis, inhibition of insulin actions
88
adrenal insufficiency
plasma concentrations of cortisol are chronically lower than normal
89
primary adrenal insufficiency
result of a loss of adrenocortical function --> addison's disease
90
hypotension
low blood pressure (could be result of loss of salt and water balance)
91
in primary adrenal insufficiency, what are the cortisol and ACTH concentrations?
cortisol is well below normal, ACTH is greatly increased bc of loss of negative feedback of cortisol
92
secondary adrenal insufficiency
inadequate ACTH secretion (can arise from pituitary disease)
93
cushing's syndrome
excess cortisol and glucocorticoids in blood from ACTH-secreting tumor - can promote uncontrolled catabolism of bone, muscle, skin, etc.
94
osteoporosis
loss of bone mass, muscles weaken - common in postmenopausal women
95
hypertension
high blood pressure (related to cushing's)
96
all hormones released during many kinds of stress
-aldosterone
-vasopressin
-growth hormone
-glucagon
-beta-endorphin
97
with stress, insulin secretion usually...
decreases
98
with stress, vasopressin and aldosterone do what?
act to retain water and Na+ within the body, and important response
99
effects of changes in growth hormone, glucagon and insulin during stress are...
to mobilize energy stores and increase plasma concentration of glucose
100
with stress, beta-endorphin does what?
may reduce pain
101
components of bone
-epiphyses = on both ends
-shaft = middle portion
-epiphyseal growth plate (b/t epiphyses and shaft) = connective tissue/cartilage
102
osteoblasts
bone-forming cells at the shaft edge of of epiphyseal growth plate that convert tissue to bone
103
chondrocytes
lay down new cartilage in the interior of the plate
104
epiphyseal closure
when growth of shaft ceases because growth plates themselves are converted to bone because of hormonal influences
105
bone age can be determined by...
taking an x-ray of bones and determining which have undergone epiphyseal closure
106
maternal malnutrition during pregnancy may....
produce irreversible growth stunting and mental deficiency in offspring
107
growth hormone main effects:
-stimulation of cell division in its many target tissues & maturation --> promotes bone lengthening and growth
-stimulates protein synthesis (muscle)
-render adipocytes more responsive to stimuli
-stimulates gluconeogenesis
-reduces ability of insulin to stimulate glucose uptake
108
growth hormone stimulates ______ in epiphyseal plates to differentiate into _______
prechondrocytes & chondrocytes (cells also start to secrete IGF-1)
109
short stature can be caused by...
decreased growth hormone secretion but also by decreased production of IGF-1 (ex: growth hormone-insensitivity syndrome)
110
IGF-2
secretion of this hormone is independent of growth hormone and is crucial during prenatal period (secreted throughout life)
111
insulin stimulates ______ and inhibits _____ (being contributing factor to growth)
stimulates storage of fat and inhibits protein degradation
112
sex steroids have 2 key effects:
1) stimulate bone growth
2) stop bone growth by inducing epiphyseal closure
113
cortisol inhibits...
growth
114
estradiol effects on growth hormone:
-stimulates secretion of growth hormone at puberty
-causes eventual epiphyseal closure
115
osteoid
a collagen matrix that the connective tissue is surrounded by in a bone
116
hydroxyapatite
crystals of calcium, phosphate, and hydroxyl ions
117
composition of bone (fractions)
1/3 osteoid and 2/3 mineral
118
mineralization
process where osteoblasts secrete collagen to form a surrounding matrix that becomes calcified
119
3 types of bone cells involved in formation and breakdown (bones are constantly remodeled)
osteoblasts, osteocytes, osteoclasts
120
osteoblasts
bone-forming cells
121
once surrounded by calcified matrix, osteoblasts become...
osteocytes
122
osteoclasts
large multinucleated cells that break down (reabsorb) previously formed bone by secreting hydrogen ions, which dissolve the crystals
123
urinary excretion of Ca2+ =
amount filtered into tubules - amount reabsorbed into blood (under hormonal control!)
124
parathyroid hormone
the protein hormone that controls the bone, kidneys, gastrointestinal tract
*produced by parathyroid glands
125
actions of PTH that increase EC Ca2+ concentration
-directly increases resorption of bone by osteoclasts (ions move from bone to EC fluid)
-directly stimulates formation of 1,25 D
-directly increases Ca2+ reabsorption in kidneys & decreases urinary Ca2+ excretion
-directly decreases reabsorption of phosphate ions in kidney & increases excretion in urine
126
vitamin D (D3 and D2)
a group of closely related steroid compounds
127
major action of 1,25 vitamin D
to stimulate intestinal absorption of Ca2+
128
calcitonin
peptide hormone secreted by cells in thyroid gland
decreases plasma Ca2+ concentration by inhibiting osteoclasts
129
osteomalacia (adults) & rickets (children)
deficient bone mineralization caused by inadequate vitamin D intake
130
hypercalcemia
chronically elevated plasma Ca2+ concentration
131
primary hyperparathyroidism
PTH increases bone resorption of Ca2+, increases kidney reabsorption of Ca+ and production of 1,25 vitamin D
132
hypocalcemia
chronically decreased plasma Ca2+ concentrations
133
primary hypoparathyroidism
loss of parathyroid gland function causes decreased bone resorption of Ca2+, decreased urinary reabsorption of Ca2+ and decreased renal production of 1,25 vitamin D
134
secondary hypoparathyroidism
vitamin D deficiency due to inadequate intake of 1,25 vitamin D due to kidney disease
135
