keywords:
Bookmark and Share



Front Back
exocrine glands
release enzymes to external environment through ducts (include sweat, oil, mucous, digestive glands)
endocrine glands
release hormones directly into body fluids
endocrine system
  • endocrine system is slower, indirect, long lasting (vs. nervous system)
  • all hormones act by binding to proteins called receptors (highly specific) (receptors can be on membrane or inside the cell)
hormones exist in 3 basic chemistry types:
1. peptide hormones
2. steroid hormones
3. tyrosine derivatives
peptide hormones
  • derived from peptides
  • manufactured in rough ER
  • water soluble and move freely through blood
  • difficulty diffusing through cell membrane of the effector (target cell of hormone)
  • attach to membrane-bound receptor and may activate intracellular second messenger (ex: cAMP, cGMP, calmodulin)
NEED TO KNOW peptide hormones:
1. anterior pituitary hormones: FSH, LH, ACTH, hGH, TSH, Prolactin
2. posterior pituitary hormones: ADH and oxytocin
3. parathyroid hormone PTH
4. pancreatic hormones: glucagon and insulin
steroid hormones
  • lipids
  • diffuse through membrane and act in nucleus
  • normally bind to receptor in cytosol
  • come only from adrenal cortex, gonads, or placenta
tyrosine derivatives
  • thyroid hormones and catecholamines (adrenal medulla hormones)
  • split: thyroids diffuse into nucleus and catecholamines act on receptors at the membrane
NEED TO KNOW steroid hormones:
1. glucocorticoids and mineral corticoids of the adrenal cortex: cortisol and aldosterone
2. gonadal hormones: estrogen, progesterone, testosterone (estrogen and progesterone also produced by placenta)
NEED TO KNOW tyrosine derivatives
1. thyroid hormones: T3 (triiodothyronine contains 3 iodine atoms) and T4 (thyroxine contains 4 iodine atoms) and; (lipid soluble, bind to receptors inside nucleus, controlled by neg. feedback mech. involving TSH (from anterior pituitary))
2. the catecholamines formed in adrenal medulla: epinephrine and norepinephrine (water soluble and bind to receptors and act mainly through second messenger cAMP) - behave like peptide hormones
negative feedback
  • endocrine glands tend to oversecrete hormone
  • control point of feedback is conduct of effector, not concentration of hormone
hormones of ANTERIOR PITUITARY
  • located in brain beneath hypothalamus
  • releases 6 peptide hormones:

1. human growth hormone (hGH)
2. adrenocorticotropin (ACTH)
3. thyroid-stimulating hormone (TSH)
4. follicle-stimulating hormone (FSH)
5. leutinizing hormone (LH)
6. prolactin
hGH
  • human growth hormone
  • peptide
  • unique bc doesnt have specific target tissue
  • stimulates growth in almost all cells
  • increasing episode of mitosis, cell size, rate of protein synthesis, amino acid transport across membrane, decrease breakdown of protein
ACTH
  • adrenocorticotropic hormone
  • peptide
  • stimulates adrenal cortex to release glucocorticoids (stress hormones) via second messenger system using cAMP
  • release of ACTH stimulated by stress
TSH
  • thyroid-stimulating hormone
  • peptide
  • stimulate thyroid to release T3 and T4 via second messenger system using cAMP
  • T3 and T4 have negative feedback effect on TSH [!] (both at anterior pituitary and hypothalamus)
FSH and LH
  • reproduction
prolactin
  • peptide
  • promotes lactation by breasts
  • although hypothalamus has stimulatory effect on other anterior pituitary hormones, mainly inhibits release of prolactin
  • milk production effect of prolactin vs. milk ejection effect of oxytocin
hormones of POSTERIOR PITUITARY
  • composed of nerve endings extending from hypothalamus
  • peptide hormones
  • oxytocin and ADH synthesized on neural cell bodies of hypothalamus and transported down axons to posterior pituitary
oxytocin
  • small peptide hormone
  • increase uterine contractions during pregnancy
  • causes milk to be ejected from breasts
ADH
  • antidiuretic hormone (vasopressin)
  • small peptide hormone
  • cause collecting ducts of kidney to become permeable to water, reducing amount of urine and concentrating urine
  • increases blood pressure, because fluid is reabsorbed
  • coffee and beer are ADH blockers that increase urine volume
hormones of ADRENAL CORTEX
  • adrenal glands are located on top of kidneys
  • separated into: adrenal cortex and adrenal medulla
  • adrenal cortex secretes only steroid hormones (mineral corticoids and gluococorticoids)
  • mineral corticoid affect electrolyte balance in blood stream
  • glucocorticoids increase blood glucose concentration and have greater effect on fat and protein metabolism
Aldosterone
  • steroid
  • mineral corticoid
  • acts in distal convoluted tubule and collecting duct to cause Na+ reabsorption and K+ secretion
  • net gain of particles in plasma--> increase in blood pressure (secondary effect)
Cortisol
  • steroid
  • glucocorticoid
  • increases blood glucose levels by stimulating gluconeogenesis in liver (creation of glucose and glycogen from AA, glycerol, and/or lactic acid)
  • stress hormone - when under stress need glucose
hormones of ADRENAL MEDULLA
  • tyrosine derivatives
  • catecholamines
  • behave like peptide hormones
  • epinephrine and norepinephrine (Adrenaline and noradrenaline)
  • epinephrine and norepinephrine are vasoconstrictors (constrict blood vessels) and vasodilators of skeletal muscle (increase blood flow)
  • consistent with fight or flight response
  • also considered stress hormones
hormones of THYROID
  • hormones are T3, thyroxine (T4), and calcitonin
  • thyroid located along trachea in front of larynx
T3 and T4
  • thyroid hormones
  • behave like steroid hormones
  • lipid soluble
  • tyrosine derivatives
  • diffuse through lipid bilayer and act in nucleus of effector
  • effect: increase basal metabolic rate (resting metabolic rate)
  • thyroid hormone secretion regulated by TSH
calcitonin
  • large peptide hormone released by thyroid
  • slightly decreases blood calcium
  • calcium levels can be controlled without calcitonin
  • tones the bone
hormones of PANCREAS (ISLETS OF LANGERHANS)
  • pancreas act as both endocrine and exocrine gland
  • endocrine hormones: peptide hormones insulin and glucagon
insulin
  • peptide hormone
  • released by b-cells of pancreas
  • associated with energy abundance
  • released when blood levels of carbs or proteins are high
  • affects carb, fat, and protein metabolism
  • in presence of insulin, carbs are stored as glycogen in liver and muscles, fat stored as adipose tissue, AA taken up by cells of body and made into proteins
  • net effect: lower blood glucose levels
  • when insulin binds, cells become highly permeable to glucose
glucagon
  • peptide hormone
  • opposite effects as insulin
  • stimulates breakdown of glycogen
  • acts via second messenger system of cAMP
  • net effect: raise blood glucose levels
hormones of PARATHYROID
  • 4 small parathyroid glands attached to back of thyroid
  • release parathyroid hormone (PTH)
PTH
  • parathyroid hormone
  • peptide
  • increases blood calcium
  • stimulates osteoclast (bone reabsorption)
  • works in kidney to slow calcium lost in urine
reproduction
except for FSH, LH, HCG (peptides), other reproductive hormones are steroids
Male reproductive system
  • gonads are called testes
  • production of sperm occurs in the seminiferous tubules of testes
  • spermatogonia arise from epithelial tissue of seminiferous tubules --> to become spermatocytes, spermatids, then spermatozoa
FSH
  • stimulate sertoli cells to surround and nurture spermatocyte and spermatids
LH
stimulate leydig cells to release testosterone
testosterone
  • the primary androgen (male sex hormone)
  • simulates germ cells to become sperm
spermatozoon
  • head (nucleus, acrosome)
  • midpiece (mitochondria)
  • tail
path of spermatozoon
  • once freed into tubule lumen, carried to epididymus to mature
  • upon ejaculation, spermatozoa propelled through vas deferens into urethra and out of penis
  • semen composed of fluid from seminal vesicles, prostate and bulbourethral glands (also called Cowper's glands)
Female reproductive system and menstrual cycle
  • all eggs are arrested as primary oocytes at birth
  • at puberty, FSH stimulates growth of granulosa cells around primary oocyte
  • granulosa cells secrete zona pellucida (form a primary follicle)
  • when stimulated by LH, theca cells secrete androgen, which is converted to estradiol (type of estrogen) by granulosa cells in presence of FSH
  • before ovulation, estradiol level rises rapidly (luteal surge)
  • luteal surge causes follicle to burst, releasing egg into body cavity
  • egg is swept into Fallopian (uterine) tube or oviduct
  • remaining portion of follicle is left behind to become corpus luteum
  • corpus luteum secretes estradiol and progesterone throughout pregnancy until it degrades into corpus albicans
estradiol
  • type of estrogen
  • steroid hormone that prepares uterine wall for pregnancy
  • typically inhibits LH secretion by the anterior pituitary
luteal surge
rapid increase in estradiol levels, causing dramatic increase in LH secretion before ovulation

from positive feedback loop of rising estrogen levels --> increases LH levels --> increase estrogen

luteal surge causes follicle to burst, releasing the egg (secondary oocyte) into body cavity.
corpus luteum
  • remaining portion of follicle
  • secretes estradiol and progesterone throughout pregnancy
  • or if no pregnancy, until corpus luteum degrades into corpus albicans
menstrual cycle
three phases:
1. follicular phase
2. luteal phase
3. flow
Fertilization and Embryology
  • fertilization takes place in fallopian tubes
  • fertilization occurs when nuclei of the ovum and sperm fuse to form the zygote
cleavage
  • begins while the zygote is still in the fallopian tube
  • zygote goes through many cycles of mitosis when zygote is comprised of 8 or more cells, it is a morula
  • become blastocyst (fluid filled ball)
  • blastocyst lodges in uterus in process of implantation (considered to be pregnant)
  • upon implantation, egg secretes peptide hormone HCG (human chorionic gonadotropin) which prevents degeneration of corpus luteum and maintains its secretion of estrogen and progesterone
HCG
  • human chorionic gonadotropin
  • peptide hormone (like LH and FSH)
  • prevents degeneration of corpeus luteum and maintains its secretion of estrogen and progesterone
placenta
  • formed from tissue of egg and mother and takes over job of hormone secretion
  • reaches full development by end of first trimester, secreting its own estrogen and progesterone while lowering secretion of HCG
determination
specialized developmental path of a cell
differentiation
specialization that occurs at end of development forming specialized tissue cell
x of y cards Next >|