Endocrine system Flashcards
(65 cards)
1
Q
GPCR –> peptide hormones
A
- peptide bound to 7a helix transmembrane (Gs or Gi)
- induces confirmational change and alpha subunit attaches to GTP and detaches from b and g.
- GTP and alpha bind adenyl cyclase which changes ATP to cAMP - a secondary messenger.
- targets downstream enzymes
- induces a phosphorylation cascade of many protein targets.
2
Q
Receptor Kinase receptor –> peptide hormones
A
no adenylyl cyclase but also a phosphorylation cascade.
3
Q
Steroid hormones
A
- Steroid hormones are derived from cholesterol; made by gonads and adrenal cortex
- Can easily cross cell membrane and bind to intracellular or intranuclear receptors
- Binding to receptors cause conformational changes and dimerization
- Steroid hormones have slower, long-lasting effects (since they affect mRNA levels)
4
Q
peptide hormones mechanism of action
A
- GPCR and receptor tyrosine kinase
5
Q
AA derivative hormones follow which mechanism of action?
A
- Catecholamines: follow GPCR - Fast and short action
- Thyroid hormones: follow steroid hormones - slow and long action
6
Q
Steroid hormones nomenclature
A
ol, one, oid
7
Q
peptide hormone nomenclature
A
in, ine
8
Q
hypothalamic-hypophysiotropic nuclei targeting anterior pituitary gland
A
GHRH GnRH CRH TRH PRH Dopamine/PIF
9
Q
paraventricular nuclei
A
Oxytocin
10
Q
supraoptic nuclei
A
ADH/vasopressin
11
Q
GHRH stimulates?
A
GH (bone, muscle, cell turnover)
12
Q
GnRH Stimulates?
A
FSH (sertoli cells, granulosa cells)
LH (Leydig cells, theca cells)
13
Q
TRH stimulates?
A
TSH (thyroid glands) - stimulate the synthesis of T3 and T4
14
Q
CRH stimulates?
A
ACTH and MSH (adrenal cortex –> cortisol and melanin)
15
Q
PRH stimulates?
A
PRL (breast)
16
Q
posterior pituitary gland secretes?
A
OT and ADH
17
Q
Role of OT
A
milk let down –> mammary glands
smooth uterine muscle contraction (+ feedback)
18
Q
Role of ADH
A
Vasopressin increase water retention through aquaporins in DCT.
19
Q
T3 and T4
A
increases BMR and temperature and necessary for child development
20
Q
thyroid C cells secrete?
A
Calcitonin –> bone, kidney; lowers serum Ca
21
Q
Parathyroid cells secrete?
A
Parathyroid hormone PTH –> bone, kidney, SI; increase serum Ca
22
Q
Thymus (in children)
A
thymosin for T cell development during childhood
23
Q
Adrenal medulla secretes?
A
Epinephrine –> sympathetic response (fast)
24
Q
adrenal cortex secretes?
A
- Cortisol –> long term stress response, inc protein catabolism, G in blood, dec inflammation and immunity
- Aldosterone –> increase Na reabsorption and thus water at DCT and collecting duct
- Sex steroids/androgens: increase Na and water retention, reproductive purposes
25
endocrine pancreas
insulin, glucagon, and somatostatin
26
Role of Insulin
decreases blood G concentration and increase glycogenesis and FA synthesis
27
Role of glucagon
increase blood G concentration and increase glycogenolysis
28
Role of somatostatin
Inhibits gastrin and thus HCl secretion in parietal cells in stomach
29
Testosterone
spermatogenesis by sertoli cells
| male characteristics
30
Estrogen
female characteristics, endometrial growth
31
Progesterone
endometrial secretion, pregnancy maintenance
32
Hormone released by heart?
Atrial Natriuretic peptide --> acts on Kidney to release pressure
33
Hormone released by Kidney?
Erythropoietin EPO --> bone marrow and increase RBC synthesis
34
Why do you pee more when you drink?
ADH is inhibited and less water is reabsorbed in DCT.
35
Neurohypophysis =
posterior pituitary gland
36
Adenophysis =
Anterior pituitary gland
37
What is the hypophyseal portal system?
it connects the anterior pituitary gland with the hypothalamus.
38
T3 and T4 synthesis
1) Na-K pump maintain gradient, Na-I symporter brings I in with Na gradient.
2) Iodination of Tyrosyl residues on TG: organification. The synthesis of DIT and MIT.
3) coupling of DIT + DIT = T4 and DIT + MIT = T3
4) endocytosis of the hormones with lysosomes for more protection.
5) T3 and T4 release in bloodstream and TG reused.
6) if I is removed from T4 --> rT3 and from T3 --> T2
39
Physiological effects of thyroid hormones
- Increased metabolic rate
- catabolic
- growth and development
40
Calcitonin
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secreted from parafollicular cells (c cells) of thyroid
reduced Ca levels in blood:
--> increased Ca in bones
--> Decreased Ca absorbtion in SI
--> Increased Ca excretion in kidney
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41
PTH
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secreted from parathyroid cells
increased Ca levels in blood:
--> antagonist to thyroid cells
--> activates Vit D
--> acts on P absorption and excretion (stays balanced in blood)
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42
Glucocorticoid are used to treat which conditions?
overactive immune system - allergy, inflammation...
43
Aldosterone function?
increase BP with increased Na resorption in Kidneys and water follows and K loss. No net increase in osmolarity (opposite to ADH).
44
Renin Angiotensin Aldosterone system (RAAS) mechanism?
- low BP sensed by macula densa and JGS cells (afferent arteries) and latter secretion of renin
- renin (liver) cleaves angiotensinogen into angiotensin I
- ACE cleaves angiotensin I into angiotensin II
- Angiotensin II stimulates the adrenal cortex to secrete aldosterone
- Aldosterone stimulates the reabsorption of Na in DCT
45
What are the cortical sex hormones?
Androgens and Estrogens
46
Adrenal cortex is derived from which germ layer?
mesoderm
47
Adrenal medulla is derived from which germ layer?
ectoderm, like the CNS and is part of the sympathetic system but secretes hormones via bloodstream
48
Catecholamines
AA derivatives, fast and short response
| Epinephrine, NE, dopamine
49
Permissive effects?
E.g. EP not as effective w/o cortisol present
50
Exocrine cells of pancreas secrete?
enzymes and bicarbonate
51
Endocrine cells of pancreas secrete?
insulin, glucagon, somatostatin, secretin, CCK, GIP
52
Glucagon
- a-cells
- primary target is hepatocytes
- stimulated by low G in blood, glucogenic AA (high P diet)
- catabolic: inc GNG, inc glycogenolysis, dec lipogenesis and inc liver lipolysis esp., inc liver ketogenesis
53
insulin
anabolic:
- decreased G from blood, stimulate AA and G take up from cells, inc glycogenesis, inc lipogenesis, inc lpl on walls and take up of CM and VLDL, inhibits ketone synthesis in liver
54
somatostatins
inhibits insulin and glucagon, and HCl secretion in stomach
55
Pineal gland secretes which hormone?
melatonin, governs the circadian rhythms
56
Organs that act as endocrine glands
kidneys (EPO), GI cells (gastrin, secretin, CCK, GIP), heart (ANP), thymus (T cell development), liver (IGF-I)
57
Gastrin
- produced at the antrum of the stomach, released by AA, peptides, parasympathetic nerves
- inhibited by acid in SI and somatostatin
- stimulate acid release from stomach, mobility of ileum and Large instestine
58
CCK
- produced in SI, stimulated by FA in SI, inhibits acid secretion in stomach, and
- potentiate the activitity of secretin on pancreas (HCO3 release) and stimulate secretion of enzymes
- stimulate gallbladder contraction
- relaxes sphincter of Oddi
59
Secretin
- produced in SI, acid in SI, inhibits acid secretion in stomach, stimulates pancreas to release bicarbonate and potentiate release of enzymes,
liver to release bicarbonate,
60
GIP
produced in SI, stimulated by fat and sugar in SI, stimulate insulin secretion.
61
ANP mechanism
high P --> stretch --> pro ANP released by heart --> selective cleavage (ANP) --> adrenal (dec Aldosterone), arterial (dec BP), and renal effects (dec Renin)
62
Terpenes
one isoprene = 5C --> 2 terpene = monoterpene
produced by plants
aromatic
63
Terpenoids
derivative of terpene --> squalene: 6 isoprene units / triterpene, converted to CH by liver.
64
Cholesterol
3 cyclohexane and cyclopentane
ampiphatic and major component of the bilayer
precursor of steroids
65
Steroids
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metabolically active derivative of terpenes
function depends on oxidation of rings and functional groups, not all steroids are hormones.
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