endocrine Flashcards
glands
tissue derived from epithelium
specialized cells that synthesize, store, + secrete chemical substances
exocrine + endocrine
exocrine glands
release secretions into ducts → carried to body surface
ex. sweat, mammary, salivary
endocrine glands
release secretions into sinusoids → passed into capillaries = carried by circulatory system to target tissues + rest of body
ex. thyroid, pituitary, adrenal
endocrine system
collection of glands + tissues of body that secrete chemical messengers into blood and ISF
integrates activities of organs + systems throughout body
NS + ES function together to maintain homeostasis
neuroendocrinology
association between endocrine + NS
brain regulates secretion from endocrine glands + hormones modify CNS function
similarities between nerve cells + gland cells
secrete chemical messengers that act on target cells
electrical activity
secrete hormones that enter vasc system
release similar substances (DA, NE, somatostatin) = act as NT, neural hormone, classic hormone
hormone signal messengers
NT = signals between neurons
neural hormone = released from neuron into blood
classic hormone = released from gland into blood
NS
neurons produce responses that are highly specific + act over short term
signals = electrical impulses conducted along axons
chemical messengers conduct impulse between neurons
ES
hormones produce responses that affect many tissues simultaneously + act over long term
signals = chemical substances released by endocrine glands → circulate in bloodstream
hormone
chemical messenger
produced + secreted by endocrine cell or tissue
travels through circulatory system to other tissues
acts upon specific target cells within tissue
hormone actions
bind to specific cellular receptors
presence or absence of receptor determines cell’s response to hormone
changing number of receptors = change cell’s sensitivity to hormone
pituitary gland
hypophysis
extends from hypothalamus as infundibulum = pituitary stalk
within bony cavity inferior to optic chiasm
anterior + posterior lobes
development of pituitary gland
derived from epithelium in oral cavity
neurohypophyseal bud grows into infundibulum below hypot. to form posterior lobe
hypophyseal pouch extends from oral cavity into mesenchyme → becomes pars intermedia before forming anterior lobe
anterior lobe of pituitary gland
adenohypophysis
true glandular mass with endocrine cells
hormones = hGH, TSH, FSH/LH, Prl, ACTH, MSH
posterior lobe of pituitary gland
neurohypophysis
axons of neurons descend from hypothalamus
hormones = ADH, oxytocin
hGH
human growth hormone
stimulates body growth + metabolism
TSH
thyroid stimulating hormone
controls thyroid gland function
FSH + LH
follicle stimulating + luteinizing hormones
control secretion of sex hormones and production of gametes (oocytes + sperm)
Prolactin
stimulates milk production in mammary gland
ACTH
controls hormone secretion by adrenal cortex
MSH
melanocyte stimulating hormone
stimulates melanin secretion by melanocytes
ADH
antidiuretic hormone/vasopressin
regulates concentration of urine = functions in regulation of blood pressure
oxytocin
stimulates uterine muscle contraction during childbirth
stimulates release of milk from mammary glands
control of posterior pituitary hormones
hypothalamus cells produce hormones → travel along stalk into posterior pituitary = released into vasculature
control of anterior pituitary hormones
hypothalamus secretes regulatory hormones to control pituitary activity
hormones secreted by pituitary control other endocrine organs
hypothalamic-hypophyseal portal system
neurons in the hypothalamus: supraoptic nucleus (ADH) + paraventricular nucleus (oxytocin) = release hormones in post. pituitary inferior hypophyseal artery (capillary network)
other cells in hypot. release hormones into primary capillary plexus (formed by superior hypophyseal artery in pituitary stalk) = carried by portal veins to anterior pituitary (form secondary capillary plexus)
hypophyseal veins leave base on ant + post pituitary = carry hormones to vasculature
feedback inhibition
releasing hormone ex. TRH
↓
stimulating hormone ex. TSH (neg feedback to hypot.)
↓
target organ or tissue ex. thyroid gland - thyroxine (neg feedback to hypot. and pituitary)
thyroid gland
contains follicles, formed by follicular cells and containing colloid → storage of thyroglobulin
synthesizes T3 (has physiological activity on cells) + T4 (more produced, deiodinated into T3)
production of thyroid hormones
follicle cells secrete hormone precursor called thyroglobulin into follicle cavity
iodine is added to thyroglobulin in the cavity
when stimulated by TSH, follicle cells convert thyroglobulin to thyroid hormones T3 + T4
follicle cells secrete T3 + T4 into connective tissue between follicles
hormones picked up by capillaries
thyroid hormones regulate metabolism
parafollicular cells
C-cells contained in follicle
produce hormone calcitonin
function in calcium regulation
parathyroid glands
4, in posterior of thyroid
oxiphil cells and principal cells → secrete parathyroid hormone
functions in calcium regulation
thyroid hormones
stimulate oxygen use, basal metabolic rate, cellular metabolism, growth + development
calcitonin
decreases Ca2+ in body fluids
increases Ca2+ deposition in bone
parathyroid hormone
increases Ca2+ in body fluids
decreases Ca2+ deposition in bone
adrenal glands
supplied by superior, middle, and inferior suprarenal arteries (branch from abdominal aorta)
sit on supramedial pole of kidneys
cortex (3 cell layers) + medulla (single cell mass)
aldosterone
mineralocorticoid
increases renal absorption of Na+ and H20
decreases renal absorption of K+
cortisol
glucocorticoid
stimulates protein, lipid, and carbohydrate metabolism
anti-inflammatory
androgens
male-type hormones
in females, adrenal cortex is the only source
stimulates growth of axillary and pubic hair
stimulates libido
adrenal medulla
innervated by both pre and post ganglionic fibres
- preG fibres synapse on chromaffin cells = release epinephrine + norepinephrine into vasculature
- postG fibres supply blood vessels to control diameter
epinephrine/norepinephrine
fight or flight response (sympathetic)
increase cardiac output
increase blood pressure
increase blood glucose
effect release of lipids from adipose tissue
pancreas
exocrine and endocrine gland
exocrine contains ducts that aggregate to main pancreatic duct; surrounds islets = endocrine
pancreatic islet
surrounded by exocrine acinar cells
contain alpha, beta, and delta cells
capillaries travel within
glucagon
secreted by alpha cells
stimulates glucose synthesis
elevates blood glucose
mobilizes lipid reserves
insulin
secreted by beta cells
stimulates lipid and glycogen synthesis and storage
stimulates glucose uptake by cells
decreases blood glucose levels
somatostatin
secreted by delta cells
inhibits secretion of glucagon and insulin (modulator)
diabetes mellitus
inability to produce or use insulin
= elevation of blood glucose levels (hyperglycemia)
excretion of glucose in urine
causes cardiovascular + vision problems
type I diabetes
10%
autoimmune disease that destroys insulin-secreting cells of islets (Beta cells)
marked reduction of insulin levels
insulin-dependent diabetes (need exogenous source injected into body)
can occur at any age; more common between 5-20
type II diabetes
90%
combination of insulin-resistance and insulin-secretory defects
target cells become less sensitive to insulin due to down-regulation of receptors
non-insulin dependent diabetes (insulin present but cannot be used effectively)
correlates with age and obesity
initial management by diet, exercise, weight loss
gonads
ovaries + testes
endocrine glands
pineal gland
in brain (superior to tectum in midbrain; inferior to corpus callosum)
unclear physiological role
secretes melatonin = regulation of biological clock (sleep cycle)
thymus gland
true gland
produces + stores T cells = dunction in cell-mediated immunity
secretes thymic hormones that act on T cells to promote proliferation and maturation
GI tract
> 20 different hormones
regulate activity of GI tract and digestive glands
kidneys
erythropoeitin = ↑ RBC production
renin = ↑ blood pressure
heart
atrial natriuretic peptide released by atria
= ↓ blood pressure
adipose tissue
leptins = appetite suppressant
↑ fat = ↑ storage in adipocytes → secretion of leptin = feedback to brain = ↓ appetite
