IU P225 Physiology Exam 5

gonadotropin-releasing hormone (GnRH)

produced: hypothalamus

stimulus: negative feedback (low estrogen & progesterone)

target: anterior pituitary

effect: stimulates release of LH & FSH

follicle-stimulating hormone (FSH)

produced: anterior pituitary

stimulus: GnRH

target: ovaries & testes

effect: follicle-delevopement & spermatogenesis

luteinizing hormone

produced: anterior pituitary

stimulus: GnRH

target: ovaries & interstitial cells of testes

effect: produce estrogen & ovulation & testosterone

estrogen

produced: ovaries

stimulus: FSH &LH

target: uterus, breasts, bones, heart

effect: thickens endometrium, preps for pregnancy, bigger boobs, mammary gland development, bone formation & vasodilation

testosterone

produced: testes

stimulus: LH

target: repro system, bones

effect: sperm production, bone formation

progesterone (endometrium & mammary glands)

produced: corpus luteum (ovaries)

stimulus: LH

target: endometrium & mammary glands

effect: prepares for implantation, prevents contractions, inhibits lactation

progesterone (respiratori centers & smooth muscle)

produced: corpus lute (ovaries)

stimulus: LH

target: respiratory centers, smooth muscle

effect: increased ventilation, vasodilation, muscle relaxation

inhibin

produced: ovaries & testes

stimulus: high levels of FSH

target: anterior pituitary

effect: inhibit release of FSH

interstitial cells

produce testosterone, promote spermatogenesis, negative feedback loop to hypothalamus & anterior pit.

sustentacular cells

surround sperms (barrier between sperm & blood), protects from immune response, secrete ABP & regulates sperm production

endocrine control of spermatogenesis

hypothalamus releases GnRH --> FSH & LH released --> testosterone & ABP released --> elevated FSH & LH cause high testosterone --> negative feedback reduces release of GnRH, LH & FSH

key word

goldilocks

oogenesis

production of female gametes/egg cells (similar to spermatogenesis)

folliculogenesis

growth & development of ovarian follicles/mature egg cells

phases of ovarian cycle

1. follicular phase

2. luteal phase

follicular phase of ovarian cycle

days 1-14; GnRH released --> stimulates FSH & LH --> follicle stimulated --> FSH causes inhibin release --> high estrogen causes LH surge via positive feedback --> triggers ovulation

luteal phase of ovarian cycle

days 15-28; ruptured follicle becomes corpus lute --> secretes progesterone & estrogen; no implantation = corpus lute degrades & restarts; implantation = corpus lute maintained by hCG

phases of uterine cycle

1. menstruation

2. proliferative

3. secretory

menstrual phase of uterine cycle

days 1-5; endometrium sheds from uterus

proliferative phase of uterine cycle

days 6-14; endometrium grows back

secretory phase of uterine cycle

days 15-28; uterus preps for implantation of egg --> endometrium degrades if no implantation

fertilization

combining of egg and sperm nuclei; results in 23 pairs of chromosomes (1 pair determines sex)

sperm capacitation

prepares sperm for fertilization by enhancing sperm motility and ability to penetrate egg

primary purpose of sperm capacitation?

getting sperm ready to fertilize the egg

stages of fertilization

1. corona radiata penetration

2. zona pellucida penetration

3. fusion of pronuclei (combine genetic material)

3 direct pregnancy hormones

estrogen, progesterone, hCG

human chorionic hormone (hCG) in pregnancy

maintains corpus luteum & endometrium; spikes between 8-12 weeks of pregnancy; prevents menstruation & stimulates placenta

progesterone in pregnancy

maintains endometrium & prevents contractions; supports placenta, develops mammary glands & prevents lactation

estrogen in pregnancy

stimulates uterine growth; increases placental blood flow, develops milk ducts

role of placenta

exchange between fetus and mother for nutrients, waste, gases, antibodies; physical and immune barrier; releases hormones

pregnancy: endocrine system

maintain pregnancy & prevent menstruation; increased progesterone, estrogen, hCH; reduced GnRH, FSH, LH

pregnancy: respiratory system

provide oxygen & remove CO2 from fetus; causes respiratory alkalosis in mother

pregnancy: cardiovascular system

deliver nutrients & oxygen, remove waste; increased plasma volume (50%), vasodilation, decreased MAP

pregnancy: digestive system

provide nutrients to fetus; motility reduced causes constipation --> greater nutrient & water absorption

pregnancy: urinary system

progesterone causes vasodilation; increases GFR, urine volume, metabolic compensation

digestive system functions

1. breakdown of food into smaller molecules

2. absorption of smaller molecules

mechanical digestion

physical breakdown that increases surface area; chewing & churning

types of mechanical digestion

mouth: chewing

stomach: churning/mixing waves

small intestine: segmentation

chemical digestion

chemical breakdown using digestive enzymes

types of chemical digestion

mouth: saliva breaks down carbs

stomach: enzymes break down proteins & fats

small intestine: accessory enzymes break down everything

GI tract

continuous tube from mouth to anus; mouth --> pharynx --> stomach --> small i. --> large i. --> anus

accessory digestive organs

mechanical = teeth & tongue

chemical = salivary glands,

liver, pancreas,

gallbladder

peristalsis

forceful, wave-like contractions primarily in intestine; propel components forward down GI tract

mixing waves

rhythmic contractions in stomach; "churning", breakdown food & mix with gastric acid, small then increase at pylorus

segmentation

alternating contractions in small intestine; causes chyme to mix with digestive enzymes (small role in moving)

mass movement

unique large waves in large intestine; clears out large areas & preps waste for elimination

enzymatic hydrolysis

breakdown of molecules into smaller molecules with water

breakdown enzymes

pepsin & proteases = proteins

amylases = carbs

lipases = fats

where is digestion of macromolecules

carbs: starts in mouth, ends in small i.

fats: starts in mouth, increases in stomach/small i.

proteins: starts in stomach, ends in small i.

what does hydrochloric acid do?

activates pepsin to breakdown proteins; reduces pH which denatures proteins; produced by parietal cells

regulation of hydrochloric acid

stimulated by: acetylcholine (primary neurotransmitter), gastrin & histamine (hormones); inhibited by: somatostatin

emulsification

bile emulsifies by breaking down into smaller droplets; CCK stimulates bile release into small intestine

bile salts

reduce surface tension and form micelles

micelles

transport lipids to enterocyte surface for absorption

gut biome

1000s of types in large intestine; help recover energy for undigested foods (fermentation) & produces vitamins

enteric nervous system

branch of ANS that regulates GI tract; communicates with PNS, SNS and CNS but also acts independently

short reflexes

receptors in GI tract communicate directly with ENS --> ENS integrates info & activates effectors

long reflexes

receptors in GI tract communicate with CNS --> CNS integrates info & communicates with ENS --> ENS activates effectors

primary digestive hormones

gastrin, secretin, cholecystokinin (CCK)

gastrin

stimulus: food (proteins) entering stomach

produced: stomach (duodenum)

target: parietal cells in stomach

effect: stimulate HCL release to breakdown proteins, growth of gastric mucosa

secretin

stimulus: low pH duodenum

produced: duodenum

target: stomach/pancreas

effect: reduces HCI secretion, stimulates bicarb release from pancreas

cholecystokinin (CCK)

stimulus: fat in duodenum

produced: duo & jejunum

target: pancreas/gb/stomach

effect: stimulates digestie enzymes from pancreas, gallbladder release bile, reduce stomach emptying

3 phases of stomach acid secretion

1. cephalic 2. gastric 3. intestinal

cephalic phase

stimulus: food (see, smell taste); activates PNS --> acetylcholine, histamine, gastrin; effect: secretion of HCI

gastric phase

stimulus: food in stomach; activates ENS --> hormones acetylcholine, gastrin, histamine; effect: increased secretion of HCI

intestinal phase

stimulus: chyme in small i.; activates SNS --> somatostatin; effect: decreased secretion of HCI

spermatogenesis vs spermiogenesis

spermatogenesis = production of sperm cells; spermiogenesis = maturation of already made sperm cells

primary homologues

penis & clitoris, ovaries & testes, labia majora & scrotum

production of sperm

mitosis --> meiosis I --> meiosis II --> spermiogenesis = sperm

hemoglobin

can release and accept hydrogen ions

potassium

maintains cell membrane potential