Chapter 11 Endocrine Glands Flashcards by Marc Weber

what are endocrine glands doing

secreting hormones, some secrete multiple

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what is the endocrine system

a major control system

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what are glands

group of epithelial cells or an organ that secretes chemical substances

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2 types of cells

endocrine glands

exocrine cells

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endocrine cells

ductless

secrete hormones into bloodstream - travel to target

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exocrine cells

are ducted

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what is a hormone

biologically active molecule that works as a messenger
often a protein
secreted by glands
travel through body to target cell (through blood)

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four types of hormones

amines
polypeptide and protein hormones
glycoproteins
steroids

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amines hormones

develop from tyrosin and tryptophan (amino acids)

thyroid hormones and catecholamines (epinephrine, norepinephrine)

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polypeptide and protein hormones

larger chains (>100 AA) are proteins, shorter = polypeptide chains
some undergo modification

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glycoproteins

protein connected to carbohydrate group

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steroids

lipids based build on cholesterol
adrenal cortex secretescorticosteroids ans sex steroids
gonads secrete sex steroids

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3 types of input that can control the hormone secretion

mineral ions or organic nutrients
neurotransmitters
hormones

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how can mineral ions and organic nutrients affect the hormone secretion

concentration can affect hormone secretion

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how can neurotransmitters affect the hormone secretion

neurotransmitter affect the stimulation of glands
some glands are controled by the autonomic nervous system
others are directly controlled by brain neurons

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how can other hormones affect the hormone secretion

tropic or trophic hormones - stimulate the secretion of other hormones

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what have polypeptides, glycoproteins and catecholamines in common

water-soluable (polar) - dissolvable in plasma
binds to receptors in membrane of target cell
activate second messanger system

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what have steroids and thyroid hormones in common

lipid soluable (non-polar)
in plasma bound to carrier proteins
binds to receptor in cytosol after passing membrane of target cell

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what does the respons of the target cell depend on

the concentration of hormone and effects of other hormones on tissue

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synergism

2+ hormones work together to produce result

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permissiveness

one hormone needs to be present in order for another hormone to be fully effective

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what effects can prolonged hormone exposure have on receptors

up-regulation

down-regulation

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what is up-regulation

# of receptors increases due to long exposure to low concentration of hormones
increase responsivness of target cell

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what is down-regulation

# of receptors decreases due to a long exposure to high concentration of hormones
decrease responsivness of target cell

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what does the concentration of hormones in blood depend on

the rate of secretion | rate of removal

how are hormones removed

excretion (kidneys - in urin) | inactivation by metabolism (breaking down in the liver)

what is the pituitary gland divided in

posterior- and anterior pituitary gland

what is the pituitary gland affected by

hypothalamus

relationship between hypothalamus and posterior pituitary gland

posterior pituitary gland stores and releases hormones that are produced in the hypothalamus

relationship between hypothalamus and anterior pituitary gland

produces and secretes hormones, but controlled by hypothalamus

where are axons located that transport hormones from hypothalamus to posterior pituitary gland

hypothalamohypophyseal tract

posterior pituitary hormones

oxytocin | vasopressin (ADH)

oxytocin

acts on smooth muscle

vasopressin (ADH)

acts on vascular smooth muscle to increase blood pressure

how does secretion of anterior pituitary gland hormones work

tropic hormones from hypothalamus cause secretion of anterior pituitary gland hormones

3 hormone sequence

1. hypophysiotropic hormone secreted from hypothalamus 2. anterior pituitary hormone 3. a hormone from anothe endocrine gland to affect target cell

in what system do tropic hormones from the hypothalamus travel

hypothalamo-hypophyseal portal system

what does the 3 hormone sequence also work as

negative feedback loop

stress hormones

cortisol | epinephrine

characteristics of cortisol

secreted by adrenal cortex | pituitary-adrenal axis

charcteristics of epinephrine

``` catecholamine secreted by adrenal medulla sympathoadrenal axis (stimulated by sympathetic nervous system - fight or flight) ```

functions of epinephrine

increases heart rate increases respiratory rate shifts blood to skeletal muscle

different regions of adrenal gland

medulla and cortex - secrete different hormones

adrenal medulla hormones

catecholamines (E, NE)

adrenal cortex hormones

corticosteroids

functions of cortisol

decrease inflammatory and immune functions increase blood suger leverl maintainance of cellular concentration of enzymes for metablolic homeostasis (liver) ...

adrenal insufficiency

low plasma cortisol level wekaness, low BP, low blood glucose result of autoimmune attack or anterior pituitary tumor

cushing´s syndrome

high plasma cortisol level diabetes-like syndromes, high BP result of ACTH-secreting tumor or adrenal tumor or long term steroid medication

where is the thyroid gland located

neck

what are thyroid follicles surrounded and filled by

follicular cells | colloid

what do follicular cells synthesize

T3 | thyroxine T4

thyroid gland hormones

triiodothryonine (T3) | thryoxine (T4)

what do triiodothryonine and thryoxine have in common

contain iodide

synthesis of thyroid hormone

iodide from ISF (blood) enter colloid iodide oxidezes and attaches to throsine ring of thyroglobulin enzymes modify and couple thyroglobulin contains hormones enters follicular cells T3 and T4 are release from throglobulin T3 and T4 are secreted into ISF (blood)

2 types of oxidized iodide attached to tyrosine ring of thyroglobulin

MIT (monoiodotyrosine) | DIT (diiodotyrosine)

what does T3 result from

one MIT attached to one DIT

what does T4 result from

two DITs coupled

what does the synthesis of thyroid hormones require

iodide

TSH

thyroid-stimulating hormone, thyrotropin from anterior pituitary

what does TSH stimulate

follicle activity

TRH

throtropin-releasing hormone, from hypothalamus

what is TSH stimulated by

TRH

what are the 3 hormone sequences to control the function of the thyroid

TRH (hypothalamus) TSH (anterior pituitary) T3/T4 thyroid gland

function of thyroid hormone

stimulates carbohydrates from small intestine = energy for metabolism increases fatty acid release from adipocytes = energy for metabolism generates heat = temp. homeostasis

hypothyroidism

lower thyroid hormone concentration in plasma than normal | enlarged thyroid or goiter

what defect can causes hypothyroidism

primary- (at thyroid), secondary- (at anterior pituitary) or tertiary (at hypothalamus)

what are symptoms of hypothyrodism

cold intolerance, weight gain

hyperthyrodism

higher thyroid hormone concentration in plama than normal

what can cause hyperthyroidism

hormone secreting tumors of thyroid | disease called Graves´ Disease

symptoms of hyperthroidism

heat intolerance weight loss goter has T3 and T4 reduce TSH secretion but cannot turn off antibody production