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URINARY SYSTEM, FLUID, ELECTROLYTE, ACID-BASE BALANCE, REPRODUCTIVE SYSTEM…
URINARY SYSTEM
FUNCTIONS:
reg. water volume, concentrations & pH levels
influences RBC production (EPO) & blood pressure (renin)
adjusts blood vol/bp by adjusting water loss in urine
controls quantities of Na, K, Cl, and other ions in urine
Ca levels controlled by calcitriol synthesis
stabilizes pH by controlling loss of hydrogen & bicarbonate ions in urine
filters waste from blood and expels it from body
proteins are broken down and excess amino acids are stored as carbs/fats; amino group is separated and becomes ammonia; ammonia is converted into urea by the liver; the kidneys filter urea into our pee
ORGANS
urinary tract: eliminates urine
ureters: transport urine toward the urinary bladder
urinary bladder: temporarily stores urine
micturition:
urination
; process of eliminating urine via contraction of muscular urinary bladder that force urine through urethra, out of body
urethra: conducts urine out of body; transports semen in males
kidneys: paired organs that produce urine; l kidney is a little higher
renal cortex: superfical region
renal medulla: secretes urine into tubules
kidney lobe: produces urine; also include cortex
renal column: cortical tissue that separate renal pyramids; extend into medulla
renal pyramids: tip (papilla) projects into renal sinus
renal papilla: discharges urine into minor calyx
major calyx: formed by 4-5 minor calyces
renal pelvis: uses peristalsis to move urine out of the kidney, into the ureter, and to the bladder; formed by 3-4 major calyces
protective layers:
renal fascia: dense fibrous outer layer; anchors kidneys to surrounding structures
perinephric fat: thick layer of adipose; surrounds fibrous capsule
fibrous capsule: layer of collagen fiber; covers outer surface of organ
hilum: point of entry for renal artery/nerves; exist for renal vein & ureter
nephrons; functional unit of kidney; consists of renal corpuscle & renal tubule
renal corpuscle: consists of glomerular capsule & glomerulus
glomerular capsule: forms outer wall of corpuscle; encloses glomerular capillaries; continuous with renal tubule
glomerulus: 50 intertwined capillaries; blood is delivered by afferent arteriole; blood leaves through efferent arteriole
podocytes: cells that have foot processes that wrap around glomerular capillaries; gaps create filtration slits
filtration slits: blood pressure forces small solutes to pass through capillary wall and into Bowman's capsule; does not allow RBCs/plasma proteins to pass
filtration membrane: fenestrated epithelium, basement membrane & foot processes of podocytes
renal tubule: the filtrate changes in composition as it travels down tubule
convoluted tubules: PCT & DCT
nephron loop: separates 2 tubules
descending limb: freely permeable to water, not solutes; reabsorbs sodium & Cl from tubular fluid
thin descending: permeable to water; impermeable to solutes
countercurrent multiplication: countercurrent is exchange of fluid moving in opposite directions; multiplication effect of exchange increases as movement continues
Na & Cl are pumped out of thick ascending limb; elevates osmotic concentration in peritubular fluid around thin descending limb
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selective reabsorption of sodium & Ca ions from tubular fluid
aldosterone: produced by adrenal cortex; stimulates synthesis of na pumps along DCT and collecting duct; reduces na loss in urine
selective reabsorption of water; concentrates tubular fluid
ADH: controls permeability of water; cause insertion of aquaporins in apical cell membrane; increases osmotic water movement; higher levels=increase in permeability of DCT; without=all fluid reaching DCT is lost in urine, large amounts of dilute urine produced
active secretion of ions, acids, drugs, & toxins into tubule
K+ ion secretion: tubular cells exchange Na in tubular fluid for excess K in body fluid; K ions diffuse into lumen of DCT through K leak channels
hydrogen ion secretion: ions generated by carbonic acid are secreted by ion-link transport; in exchange for Na in tubular fluid; bicarbonate ions diffuses into bloodstrea; prevents changes in plasma pH
secretion acidifies tubular fluid; elevates blood pH; accelerates when blood pH falls
ascending limb: impermeable to water; removes Na & Cl ions from tubular fluid
thick ascending: impermeable to water & solutes; active transport mechanisms pump Na & Cl from tubular fluid to peritubular fluid of medulla
collecting duct: receive tubular fluid from many nephrons; carries it towards renal sinus
tubular secretion: solutes pass from bloodstream into tubules
tubular reabsorption: solutes pass back into blood stream
REFLEXES
urine voiding reflex: invloes spinal reflexes and the pontine micturition center
bladder contains 200 mL of urine, urge to urinate appears
stretch receptors send impulses to pontine micturition center; initiating sacral spinal reflex
detrusor muscle contracts; internal & external urethral sphincters relax
FLUID, ELECTROLYTE, ACID-BASE BALANCE
FLUID COMPARTMENTS: total body water vol = 45 L
extracellular fluid compartment; ECF; 1/3 outside cells; 33%
interstitial fluid: IF; 12 L in space between cells;
ex. lymph, CSF, humors of eye. synovial fluid, serous fluid, gastrointestinal secretions
plasma: 3 L
high level of Na+ (most abundant positive ion in ECF)
high level of Cl-
(most abundant negative ions in EFC)
intracellular fluid compartment: IFC; 2/3 in cells; 66%
high level of K+ (most abundant positive ion in IFC)
high level of HPO42- (most abundant negative ion in IFC)
ELECTROLYTES: ions that can dissociate in water; can conduct electrical current
electrolyte balance: refers to salt balance;
salts controls fluid movement, provide minerals for excitability, secretory activity, membrane permeability;
salt enters body by ingestion & metabolism, lost by faces, urine, sweat, vomit
estrogen: increases NaCl reabsorption; H2O retention during menstrual cycle & pregnancy; higher bp
progesterone: decreases NaCl; blocks aldosterone; promotes Na+ and H2O loss
sodium salt: contributes 280 mOsm of 300; exerts significant osmotic pressure; water filtrate follows Na+
aldosterone: released by adrenal cortex; triggered by angiotensin II; reabsorbs Na and secretes K; also triggered by increase K+ concentration
ANP: released by atria of heart in response to stretch; decreases bp & blood vol; decreases ADH, renin, aldosterone production; increases excretion of Na & water; promotes vasodilation directly & by decreasing angiotensin II
potassium balance: affects neurons & muscle cells; high K reduced excitability; low K hyperpolarization
H+ shifts opposite of K to maintain cation balance
ECF K levels fall with alkalosis
ECF K levels rise with acidosis
calcium: 99% of Ca in bones; Ca+ in ECF is important for blood clotting, cell membrane permeability, secretory activity, neuromuscular excitability
hypercalcemia: inhibits neurons & muscle cells, may cause heart arrhythmia
hypocalcemia: high excitability and muscle tetany
PTH: parathyroid hormone promotes increase in Ca levels; osteoclasts break down matrix & release Ca in blood; kidney increase Ca reabsorption; small intestine increases Ca absorption
BF OSMOLALITY: maintained at 280-300 mOsm
rise in osmolality stimulates thirst & ADH release
decrease in osmolality inhibits thirst & ADH
increase in ECF osmolality: decreases saliva, stimulates thirst; decreases blood pressure, stimulates angiotensin II
ACID-BASE BALANCE: pH affects all functional proteins & biochemical reactions
venous blood & interstitial pH = 7.35
arterial blood pH = 7.4
alkalosis: pH >7.45
acidosis: pH <7.35
ICF pH = 7.0
respiratory defense
renal regulation: H+ secretion occurs in PCT and collecting ducts
chemical buffer: lungs eliminate carbonic acid by eliminating 2; kidney eliminate acids to prevent metabolic acidosis; kidneys regulate blood levels of alkaline substances
REPRODUCTIVE SYSTEM
MALE REPRODUCTIVE SYSTEM: produces large quantities of gametes; half a billion sperm per day
scrotum: encloses the testes; suspended inferior to perineum; anterior to anus; posterior to base of penis; divided by raphe of scrotum; each testis lies in scrotal cavity
testes: male gonads: secrete male sex hormones (androgens); produces male gametes (sperm); produce immobile sperm
tunica vaginalis: serous membrane; lines scrotal cavity; reduces friction between surfaces
temp reg. normal sperm development require temp 2-6 C lower than body temp; muscles relax/contract to move testes away/from body
tunica albuginea: deep to tunica vaginalis; dense layer of connective tissue rich in collagen fibers; continuous with fibers surrounding epididymis; fibers form septa testis that converge near entrance to epididymis; supports blood/lymphatic vessels of testis & efferent ductules
seminiferous tubules: location of sperm production; connect to rete testis; efferent ductules connect rete testis to epididymis
interstitial endocrine cells: produce androgens; namely testosterone
dartos muscle: layer of smooth muscle in dermis of scrotum; causes wrinkling of scrotal surface
cremaster: layer of skeletal muscle deep to dermis; tenses scrotum & pulls testes closer to body due to sexual arousal or decreased temp
pathway of sperm
testis
epididymis
ductus deferens
ejaculatory duct
urethra
seminal gland (vesicles): tubular glands; many 60% of semen
prostate: encircle proximal portion of urethra; forms prostatic fluid- slightly acidic; 25% of semen; ejects into prostatic urethra by peristalsis
bulbo-urethral gland: secrete thick, alkaline mucus; neutralizes urinary acid of urethra; lubricates tip of penis
spermatic cords: extends between abdominopelvic cavity and testes; consist of layers of fascia & muscle; enclose ductus deferens, blood vessels, nerves, lymphatic vessels
ductus deferens: begins at the tail of epididymis; lumen enlarges into the ampulla of ductus deferens; wall contains thick layer of smooth muscle; store inactive sperm for months
epididymis: start of reproductive tract; monitor & adjust composition of fluid; recycle damaged sperm; store sperm & facilitate their functional maturation
ejaculatory duct: passageway for sperm; penetrates wall of prostate & empties into prostatic urethra
FEMALE REPRODUCTIVE SYSTEM: produces one gamete per month; retains & nurtures zygote
uterine tubes: carries oocytes to uterus; if sperm reaches oocyte, fertilization is initiated; oocyte matures to ovum
uterus: encloses and supports developing embryo
ovaries: female gonads; releases one immature gamete (oocyte) per month; produces hormones
vagina: connects uterus with exterior
SPERMATOGENESIS: process of sperm production; begins at puberty; involves mitosis, meiosis, spermiogenesis
spermatogonia: stem cells; divide by mitosis to produce two daughter cells; one remains a spermatogonium; second differentiates into primary spermatocyte
primary spermatocytes: begin meiosis & form secondary secondary spermatocytes
secondary spermatocytes: differentiate into spermatids
spermatids: immature gametes; differentiate into sperm
sperm: lose contact with wall of seminiferous tubule; enter fluid in lumen
spermiogenesis: differentiation of spermatid into a sperm; spermatid sheds excess cytoplasm & produces a flagellum
spermiation: sperm loses attachment to nurse cell; enters lumen of seminiferous tubule
nurse cells: Sertoli cells; maintenance of blood testis barrier; support mitosis & meiosis; support spermiogenesis; secretion of inhibin; secretion of ABP
OOGENESIS: ovum production
oogonia: stem cells; contained in fetal ovaries & under go mitosis
primary oocytes: diploid cells; remain in prophase I until puberty; located in outer ovarian cortex
secondary oocytes: formed by primary oocytes that finish meiosis I; diploid cell
ovary releases secondary oocyte; suspended in metaphase II
meiosis II is completed upon fertilization; a mature ovum is formed
cytoplasm divides evenly; produces one secondary oocyte; also prodiced 2-3 polar bodies that disintergrate
primordial ovarian follicle: primary oocyte & surrounding follicle cells
primary follicle: formed by activated primordial ovarian follicle; has a zona pellucida
zona pellucida: area of intermingling microvilli
secondary ovarian follicle: forms from primary
Graafian follicle: follicular fluid accumulates between inner & outer cell layers; 2x size of 2nd ovarian follicle
ovarian cycle: monthly process of maturation, ovulation, degeneration of Graafian follicle
follicular phase: preovulatory phase; rising LH prompt completion of meiosis I; corona radiata remain associated w secondary oocyte
Graafian follicle creates bulge in ovary
oocyte and its follicular cells project into antrum
cells adjacent form layer of thecal endocrine cells that produce estrogen
luteal phase: secreted moderate amount of estrogen; begins degenerating 12 days after ovulation
corpus luteim forms from remaining granulosa cells under stimulation of LH
cholesterol creates yellow color & is converted to progesterone;
corpus albicans is formed from nonfunctional curpus luteum as fibroblasts invade & form scar tissue
ovulation:
Graafian follicle releases secondary oocyte into pelvic cavity
oocyte moves into uterine tube by contact with fimbriae or fluid currents
FSH: triggers start of ovarian cycle. at puberty
LH surge: day 14; completion of meiosis I; rupture follicular wall; ovulation occurs
uterine cycle: repeating series of changes in endometrium
secretory phase: stimulated & sustained by estrogen provided by ovarian follicles; functional layer becomes highly vascularized
menstrual phase: degeneration of endometrial functional layer; leads to menstruation
proliferative phase: epithelial cells of uterine glands mutliple & restore integrity of uterine epithelium