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Flashcards in endocrine Deck (34):
1

peptide hormones

made up of amino acids
derived from polypeptides cleaved during post transcriptional modifications
polar, charged
cannot pass through membrane
bind to extracellular receptors and triggers transmission of signal
effect is rapid but short lived
water soluble, travel freely in bloodstream

2

steroid hormones

derived from cholesterol
produced by gonads and adrenal cortex
nonpolar, not charged
can pass through membrane
receptors usually intracellular
effect is slow but long lived, bc cause conformational changes
not water-soluble, require proteins to be carried in bloodstream, very specific carriers

3

amino acid-derivative hormones

less common
epinephrine, norepinephrine, triiodothyronine(T3), and thyroxine(T4) (thyroid hormones)
chemistry is less predictable, can bind extracellular or intracellular
derived from 1 or 2 amino acids with some modifications

4

endocrine organs

hypothalamus
anterior pituitary
posterior pituitary
thyroid
parathyroid
adrenal cortex
adrenal medulla
pancreas
gonads
pineal gland
other (kidney and heart)

5

hypothalamus

bridge b/w nervous and endocrine systems
3 nuclei
role in emotional experience, aggression, sexual behavior, metabolism, temperature, regulation, and water balance
releases many tropic hormones to interact with the anterior and posterior pituitary glands

6

hypothalamus and anterior pituitary hormones

Gonadotropin-releasing hormone (GnRH)--> follicle-stimulating hormone (FSH) and Luteinizing hormone (LH)
Growth hormone-releasing hormone (GHRH)--> growth hormone (GH)
Thyroid-releasing hormone(TRH)-->thyroid-stimulating hormone(TSH)
corticotropin-releasing factor (CRF)-->adrenocorticotropic hormone (ACTH)

7

hypothalamus and posterior pituitary

does not receive tropic hormones but neurons in the hypothalamus send axons down the pituitary stalk directly into the posterior pituitary
this signals the release of oxytocin and antidiuretic hormone

8

oxytocin

hormone that stimulates uterine contractions during labor and milk let down during lactation
also envolved in bonding behavior

9

antidiuretic hormone (ADH)

vasopressin
increases reabsorption of water in collecting ducts of kidneys
secreted in response to increased plasma osmolarity or increased concentration of solutes within the blood

10

anterior pituitary

FSH (tropic act on gonads)
LH (tropic act on gonads)
Adrenocorticotropic hormone (ACTH) (tropic act on adrenal cortex)
Thyroid-stimulating hormone (TSH) (tropic act on thyroid)
Prolactin (direct, milk production)
Endorphins (direct, decrease perception of pain)
Growth Hormone (direct, promote growth of bone and muscle)

11

posterior pituitary

stores 2 hormones that are synthesized in the hypothalamus
simply released when received signals from hypothalamus
ADH and oxytocin

12

thyroid

controlled by TSH from anterior pituitary gland
calcitonin produced by C-cells
releases triiodothyronine (T3) and thyroxine (T4) produced by follicular cells
3 and 4 refer to # of iodine atoms attached to tyrosine
increasing T3 and T4 increases cellular respiration
reset basal metabolic rate by making energy production more or less efficient

13

calcitonin

acts to decrease plasma calcium levels in 3 ways:
1. increased calcium excretion from kidneys
2. decreased calcium absorption from the gut
3. increased storage of calcium in the bone
high levels of calcium in blood stimulates secretion from C-cells

14

function of calcium

bone structure and strength
regulation of muscle contraction
clotting of blood (is a cofactor)
also plays role in cell movement, exocytosis, and neurotransmitter release

15

parathyroid gland

produces parathyroid hormone (PTH)
serves as an antagonistic hormone to calcitonin, raising blood calcium levels
opposite mechanisms of calcitonin
activates vitamin D, required for absorption of calcium and phosphate in gut

16

adrenal cortex

secretes corticosteroids
steroid hormones divided into 3 classes:
1. glucocotricoids
2. mineralocorticoids
3. cortical sex hormones

17

glucocorticoids

steroid hormones
regulate glucose levels
affect protein metabolism
exp. cortisol and cortisone, raise blood glucose by gluconeogensis and decrease protein synthesis, also decrease inflammation and immunologic responses
under control of ACTH from anterior pituitary gland

18

mineralocorticoids

steroid hormone
salt and water homeostasis, biggest effect on kidneys
exp. aldosterone, increases sodium reabsorpition in distal convoluted tubule and collecting duct of nephron
under control of renin-angiotensin-aldosterone system

19

renin-angiotensin-aldosterone system

decreased blood pressure causes juxtaglomerular cells of kidney to release renin
renin cleaves an inactive plasma protein angiotensinogen to its active form angiotensin I
angiotensin I is converted to angiotensin II in lungs
angiotensin II stimulates adrenal cortex to secrete aldosterone to restore blood pressure

20

cortical sex hormones

androgens and extrogen
little role in males
females more sensitive to disorders of hormone production

21

functions of corticosteroids

The 3 S's
Salt (mineralocorticoids)
Sugar (glucocorticoids)
Sex (cortical sex hormones)
the hormones regulate these things

22

adrenal medulla

production of sympathetic hormones
epinephrine and norepinephrine (are catecholamines)
secreted directly into circulation
control the sympathetic and parasympathetic NS

23

pancreas

exocrine and endocrine function
produce digestive enzymes
islets of Langerhans are cells that produce hormones
pancreas secretes glucagon, insulin, and somatostatin

24

islets of Langerhans

contain 3 distinct cells:
Alpha-cells secrete glucagon
Beta-cells secrete insulin
Delta-cells secrete somatostatin

25

glucagon

secreted during times of fasting
when glucose levels are low
stimulates the degradation of protein and fat, conversion of glycogen to glucose, and production of new glucose by gluconeogensis

26

insulin

secreted when blood glucose levels are high
antagonist of glucagon
induces muscle and liver cells to take up glucose and store it a glycogen
stimulates anabolic processes, fat and protein synthesis

27

hyperglycemia

result in diabetes mellitus
excess blood glucose
caused by underproduction, inefficient secretion, or insensitivity to insulin

28

type I diabetes

insulin-dependent
autoimmune destruction of beta-cells in pancreas
produce little to no insulin
require regular injections of insulin to permit entry of glucose into cells

29

type II diabetes

non-insulin-dependent
receptor-level resistance to the effects of insulin
part inherited and part environmental, like diet and obesity
pharmaceutical agents can be taken to help body more effectively use the insulin it produces

30

somatostatin

inhibitor of both insulin and glucagon secretion
high blood glucose and amino acid concentrations stimulate secretion
produced by hypothalamus, functions to decrease growth hormone secretion in addition to functions in pancreas

31

gonads

testes secrete testoseterone stimulated by FSH and LH, development of male reproductive system
ovaries secrete estrogen and progesterone stimulated by FSH and LH, development of female reproductive system

32

pineal gland

secretes melatonin
involved in circadian rhythms
sleep-wake cycle

33

erythropoietin

produced by the kidneys
stimulates bone marrow to increase production of erythrocytes
secreted in response to low oxygen levels in blood

34

atrial natriuretic peptide (ANP)

released by the heart
helps regulate salt and water balance
stimulated when cells in atria are stretched from excess blood volume
hormone promotes excretion of sodium, increasing urine volume
lowers blood pressure and volume, antagonist to aldosterone