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MCAT Biology Lecture 5


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made: thyroid
effects: decreases blood calcium level
made: ovaries
effect: prepares and maintaines uterus for pregnancy
Placenta hormones
HCG, (Estrogens, Progesterone... in addition to ovaries).
made: ovaries
effect: growth of mother sex organs, causes LH surge
made: testes
effect: secondary sex characteristics, closing of epiphyseal plates
Difference between endocrine and exocrine glands.
exocrine release enzymes to external environment through ducts, ie sweat, oil, digestive stuff.
endocrine releases directly into body fluid.
Three types of hormones
peptide, steroid, tyrosine derivatives
target cell of hormone
peptide hormone properties
peptide derivative, water soluable.
have hard time diffusing through effector cell membrane.
specific peptide hormones
1. anterior pituitary: FSH, LH, ACTH, hGH, TSH, Prolactin
2. posterior pituitary: ADH, oxytocin
3. parathyroid: PTH
4. pancreatic: glucagon, insulin
specific second messengers
cAMP, cGMP, calmodulin -- often lead to cascade
steroid hormone properties
cholesterol derived, similar.
formed in smooth ER & Mito.
lipids, so require protein transport in blood.
can diffuse through effector membrane.
tends to increase protein production
specific steroid hormones
1. glucocorticoids and mineral corticoids of adrenal cortex: cortisol, aldosterone
2. gonadal hormones: estrogen, progesterone, testosterone
specific tyrosine derivatives
1. thyroid hormones: T3, T4
2. catecholamines adrenal medulla: epinephrine and norepinephrine
thyroid hormone properties
lipid soluable, use plasma protein carriers. Bind to receptors in nucleus. Latent response, longer duration.
epinephrine and norepinephrine properties
water soluable, bind to receptors on target tissue, act through 2nd messenger cAMP
negative feedback
gland lags behind effector... high hormone concentrations are not feeding back. gland responds to BODY not body to GLAND. glands try to normalize body.
anterior pituitary
beneath hypothalmus in brain.
releases prolactin, hGH, ACTH, TSH, FSH and LH
human growth hormone (hGH)
made: anterior pituitary
effects: all body cells
action: stimulates growth, increasing protein production
made: anterior pituitary, stress response
effects: adrenal cortex
action: adrenal cortex releases glucocorticoids
made: anterior pituitary
effects: thyroid
action: thyroid releases T3 and T4, thyroid cells grow
made: anterior pituitary
effects: breasts
action: stimulates milk production
posterior pituitary
support tissue for hypothalamus.
hypothalmus makes oxytocin and ADH, which are released by post. pituitary
made: hypothalamus
action: uterine contractions and milk ejection
made: hypothalamus
effects: kidney collecting ducts
action: concentrates urine, retains water.
adrenal cortex
on top of kidney, cortex is outside part.
releases Aldosterone, Cortisol, ie minteral corticoids and glucocorticoids.
made: adrenal cortex
effects: Na+ absorption, K+ secretion in tubule of kidney, also increases blood pressure
made: adrenal cortex
effects: stimulates gluconeogenesis in liver, degrades adipose tissue for energy, diminishes immune response
catecholamines - epinephrine, norepinephrine
made: adrenal medulla
effects: 'fight or flight', like in sympathetic NS, but longer lasting.
gland located along trachea in front of larynx
releases T3, T4 and calcitonin
T3 & T4
made: thyroid
difference is 3 vs 4 iodine atoms
effects: increase basal metabolic rate.

release regulated by TSH
located near kidney
both endo and exocrine gland.
releases insulin and glucagon.
made: pancreas
effects: lowers blood glucose levels, by increasing membrane permeability to glucose (except in brain)
made: pancreas
effects: raise blood glucose levels, by promoting gluconeogenesis and glycogenolysis in liver. Also breaks down adipose tissue. (fat)
small glands attached to back of thyroid, releases PTH
PTH, parathyroid hormone
made: parathyroid
effects: increase blood calcium, regulated by calcium ion concentration in plasma
seminiferous tubules
sperm production occurs there
FSH - follicle stim. hormone
made: anterior pituitary
effects: growth of follicles in female, sperm production in male
made: anterior pituitary
effects: causes ovulation, stimulates estrogen and testosterone secretion
stimulates corpus luteum to grow and release estrogen and progesterone
male sex hormone, primary is testosterone. Also responsible for secondary sex characteristics.
sperm growth phases
epithelial tissue, spermatogonia, spermatocytes, spermatids, spermatozoa.
egg and sperm fuse to form
zygote undergoes many mitosis resulting in ball of cells called morula
hallow ball of cells derived from morula implanted in wall of uterus
once cell type affects the direction of differentiation of another cell type. differentiation "determines" cell fate.

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