Chapter 19- Endocrine System Flashcards
general characteristics
- chronic regulation of homeostasis
- -slow and prolonged responses
- -acute=nervous system
- interrelated with nercous system
- -hypothalamus and posterior pituitary
- ductless system
- -hormones produced by specialized cells
- -carried in blood stream
hormones
- substance synthesized by a specific organ or tissue and secreted:
- -secreted into extracellular spaces=paracrine signaling (no blood needed)
- -blood carries it to other sites=endocrine signaling
- act on target cells
- -have specific receptors for specific hormones
chemistry of hormones: categories
- steroids: made from cholesterol, non polar
- peptides: polar
- amines
- derived from amino acids
- polar and non-polar - eicosanoids
- most are non-polar
- paracrine signals (prostaglandins)
steroid hormones
- lipid soluble therefore can cross cell membrane
- -transduction=regulation of DNA transcription
- examples
- -estrogens like estradiol
- -androgens like testosterone
- -aldosterone
- -cortisol
amine hormones
- derived from either tyrosine or tryptophan
- some are membrane soluble (thyroxine)
- some are not (epinephrine)
- most important ones are made by:
- -thyroid
- -adrenal medulla
other hormones
peptide hormones -short chains of amino acids --cannot cross cell membrane -all pituitary hormones eicosanoids -derived from fatty acids --most cross cell membranes -coordinate functions in extracellular fluid --ex. prostaglandins
control of hormone secretion
negative feedback
- gland is sensitive to concentration of substance
- concentration exceeds limits–> prevents gland from secreting hormone
- concentration decreases->secretion increases
- results in relatively stable concentration of both substance and hormone
hypothalamus
- sends signals to the body and the pituitary gland
- -really 2 separate glands: developmental origins are key to function
- pituitary is the most important endocrine gland for regulation
- basically runs endocrine system
pituitary gland
2 lobes posterior (neural) -does not make any hormones -mostly hypothalamic axons anterior (endocrine) -5 types of endocrine cells -controlled by hypothalamic regulatory hormones --releasing hormones --inhibiting hormones
posterior pituitary hormones
Oxytocin
ADH
oxytocin
-posterior pituitary
-causes contraction of muscles in uterine walls
-causes muscles associated with milk ejection to contract
-cause contraction of prostate gland
-significant in emotional bonding
–familial
–romantic
does NOT make milk, just causes release
antidiuretic hormone
- causes kidney to decrease water excetion
- increases blood volume-> rise in BP
anterior pituitary hormones
- melanocyte stimulating hormone (MSH)
- follicle stimulating hormone (FSH)
- luteinizing hormone (LH)
- growth hormone (GH)
- thyroid stimulating hormone (TSH)
- prolactin (PRL)
- adrenocorticotropic hormone (ACTH)
melanocyte stimulating hormone
-increases melanin secretion
follicle stimulating hormone
- testes to produce sperm
- follicular development in ovary
- stimulate secretion of estrogen
luteinizing hormone
- promotes secretion of sex hormones
- release of oocyte
growth hormone
- GH
- increase size and rate of reproduction of body cells
- targets muscles and bones-mobilizes fat and glucose
- enhances movement of amino acids through membranes
- secreted throughout life, increases at puberty
thyroid stimulating hormone
- TSH
- controls secretion of thyroid hormone
prolactin
- PRL
- targets mammary tissue
- milk production/secretion
Adrenocorticotropic hormone
- ACTH
- stimulates adrenal cortex to produce corticosteroids
thyroid gland
- 2 lobes and isthmus
- -inferior to larynx
- Follicular cells
- -line follicle cavities (filled with thyoglogulin colloid)
- -remove Iodine from blood
- -secrete T3 and T4
- Parafollicular cells
- -produce calcitonin
thyroid hormones: follicular cells
Thyroxine (T4) -increase glycogenolysis -increase protein synthesis -increase growth Triiodothyronine (T3) -same as T4 but 5x's more potent
thyroid hormones: parafollicular cells
calcitonin
- DECREASE blood calcium and phosphate
- increase renal excretion
- increase osteoblast activity
parathyroid glands
posterior surface of thyroid
- many tightly packed secretory cells
- -oxyphil and transitional cells=immature
- -chief cells=produce parathyroid hormone
parathyroid hormones
parathyroid hormone (PTH)
- INCREASE blood calcium
- decrease renal calcium and phosphate excretion
- increase osteoclast activity
- increase calcitriol=intestinal calcium absorption
thymus
thoracic cavity, posterior to sternum
- produces thymosin
- -enhances lymphocyte production and competence
- -most active in infancy and childhood
adrenal glands
adrenal cortex
adrenal medulla
adrenal cortex
- glomerulosa
- -aldosterone: sodium retention
- fasciculata
- -cortisol: glycogen formation
- reticularis
- -androgens: secondary sexual characters
adrenal medulla
- chromaffin cells which are modified postganglionic cells of the SNS (neurons)
- -epinephrine and norepinephrine
- only gland directly stimulated from brain
kidneys
- renin: start cascade to increase blood pressure
- erythropoietin (EPO): erythrocyte production
- calcitriol: increases absorption of digested calcium
heart
atrial natriuretic peptide (ANP)
- suppresses aldosterone and ADH
- decrease blood volume and blood pressure
pancrease
posterior to stomach -attaached to duodenum by duct -exocrine and endocrine function islets of langerhans=endocrine function -alpha cells --glucagon=increases blood sugar -beta cells --insulin= decreases blood sugar -delta cells --somatostatin: inhibits glucagon and insulin secretion --antagonizes GH
male gonads
interstitial cells -secrete androgens --testosterone ---stimulate nurse cells ---secondary sex characteristics nurse cells -secrete inhibin --decrease FSH from anterior pituitary --stimulate spermatogenesis
female gonads
follicles=pre-ovulation -estrogens: --maturation of oocyte -- endometrial development -inhibin: --decrease FSH from anterior pituitary corpus luteum: post-ovulation -estrogens (estradiol) -progesterone --prepares body for pregnancy
pineal gland
pineacytes in epithalamus
- melatonin
- -circadian rhythms
- -possible role in puberty
