Exam 5 study guide

Urinary system

kidneys, ureters, urinary bladder, urethra

Kidney location

posterior abdominal cavity, one on each side of the vertebral column, retroperitoneal, at roughly T12 to L3. two bean-shaped organs located on either side of the spine, just below the rib cage in the retroperitoneal space of the lower back

Kidney functions

filter blood to remove metabolic wastes, regulate blood volume and pressure, maintain electrolyte and pH balance, produce hormones such as erythropoietin and renin

UTI

infection of the urinary system, most commonly caused by bacteria such as E. coli entering the urethra

UTI risk factors

shorter urethra in people with female anatomy, catheter use, sexual activity, urinary tract abnormalities, suppressed immunity

Nephron

the functional unit of the kidney responsible for filtering blood and producing urine, spanning the renal cortex and medulla

Renal cortex

outer region of the kidney containing the glomeruli, Bowman's capsule, proximal convoluted tubule, and distal convoluted tubule

Renal medulla

inner region of the kidney containing the loops of Henle and collecting ducts

Parts of a nephron

glomerulus, Bowman's capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, collecting duct

RAA pathway trigger

decrease in blood pressure or blood volume, or low sodium levels detected by the kidneys

Renin

an enzymatic hormone produced, stored, and secreted by specialized cells in the kidneys to regulate systemic blood pressure, blood volume, and sodium-potassium balance

Angiotensinogen

inactive protein produced by the liver; substrate for renin

Angiotensin I

inactive precursor formed in the blood; functions as a precursor starting substance that is modified or converted to create another substance.

ACE

enzyme produced by endothelial cells in the lungs that converts angiotensin I to angiotensin II

Angiotensin II

active hormone that causes vasoconstriction and stimulates aldosterone release, raising blood pressure

Aldosterone

hormone produced by the adrenal cortex that increases sodium and water reabsorption in the distal tubule and collecting duct, raising blood volume and pressure

RAA homeostasis model

drop in blood pressure triggers juxtaglomerular cells to release renin, activating the RAA cascade involving the kidney, liver, and lungs, ultimately restoring blood pressure

Kidney disease risk factors

diabetes, hypertension, obesity, family history, advancing age, smoking, certain autoimmune diseases

Preemptive kidney transplantation

receiving a kidney transplant before dialysis becomes necessary; associated with better outcomes and quality of life

Dialysis

procedure that filters waste and excess fluid from blood using a semipermeable membrane when the kidneys cannot

Diffusion in dialysis

wastes move from high concentration in the blood across the dialysis membrane into the dialysate solution down their concentration gradient

Uremia

buildup of urea and other metabolic wastes in the blood because the kidneys can no longer filter them from plasma

Acidosis

kidneys fail to excrete hydrogen ions or reabsorb bicarbonate, causing blood pH to drop

Anemia

damaged kidneys produce insufficient erythropoietin, reducing red blood cell production

Hypertension

sodium and water retention increases blood volume and activates the RAA pathway

Edema

fluid accumulates in tissues because the kidneys cannot excrete enough sodium and water

Hypocalcemia

kidneys cannot activate vitamin D, reducing calcium absorption from the gut

Filtration

passive movement of fluid and small solutes from glomerular capillaries into Bowman's capsule due to hydrostatic pressure; first step in urine formation

Reabsorption

recovery of useful substances such as glucose, amino acids, water, and ions from the filtrate back into the peritubular capillaries

Secretion

active transport of wastes and excess ions from the peritubular capillaries into the tubular fluid for excretion

waste products

urea from protein metabolism, creatinine from muscle metabolism, uric acid from nucleic acid breakdown

Filtration membrane

allows water, small ions, glucose, amino acids, urea, and creatinine to pass; blocks plasma proteins and blood cells

Blood pathway

renal artery, segmental arteries, interlobar arteries, arcuate arteries, interlobular arteries, afferent arteriole, glomerulus, efferent arteriole, peritubular capillaries or vasa recta, then venous drainage to renal vein

Filtrate reabsorption

approximately 99% of filtrate is reabsorbed; only about 1% becomes urine

Afferent vs efferent arteriole

the afferent arteriole is wider, creating high hydrostatic pressure in the glomerulus needed for filtration

Size-selective filtration

plasma is filtered based on molecular size; small molecules pass freely while large proteins and cells are retained

Hydrostatic pressure

pressure exerted by a fluid against a membrane; drives fluid out of capillaries

Osmotic pressure

pressure generated by solutes that draws water toward the side of higher solute concentration; opposes filtration

Net filtration pressure

glomerular hydrostatic pressure minus capsule hydrostatic pressure minus glomerular osmotic pressure

Tmax

the maximum rate at which carrier proteins can reabsorb a given solute; once reached, excess solute passes into urine

Carrier proteins

have a finite number of binding sites and maximum transport speed; become rate-limited when all sites are occupied

Glucosuria in diabetes

blood glucose exceeds the Tmax for glucose carriers so excess glucose spills into urine

Proximal convoluted tubule

reabsorbs most filtered glucose, amino acids, sodium, chloride, water, and bicarbonate; secretes hydrogen ions and some drugs

Loop of Henle descending limb

permeable to water but not solutes; water leaves by osmosis into the medullary interstitium, concentrating the filtrate

Loop of Henle ascending limb

impermeable to water; actively transports sodium, potassium, and chloride out, building the medullary osmotic gradient

Distal convoluted tubule

reabsorbs sodium and calcium under aldosterone and PTH control; secretes potassium and hydrogen ions

Collecting duct

fine-tunes water reabsorption under ADH control; secretes hydrogen ions for acid-base balance

Countercurrent multiplication

process in the loop of Henle that builds a high-osmolarity gradient in the renal medulla, allowing the collecting duct to produce concentrated urine when ADH is present

SA/V ratio and nephrons

small nephrons have a high surface-area-to-volume ratio, maximizing contact between the tubular epithelium and filtrate for efficient reabsorption

Male reproductive divisions

gonads are testes; ducts are epididymis, vas deferens, ejaculatory duct, urethra; external genitalia are penis and scrotum; accessory glands are seminal vesicles, prostate, and bulbourethral glands

Vas deferens

muscular tube that propels sperm from the epididymis to the ejaculatory duct during ejaculation

Ejaculatory duct

formed by the union of the vas deferens and seminal vesicle duct; passes through the prostate and opens into the urethra

BPH

benign prostatic hyperplasia; enlargement of the prostate that compresses the urethra causing difficulty urinating

Bulbourethral gland

secretes alkaline fluid before ejaculation to neutralize acidic urine residue and lubricate the urethra

Pathway of sperm

seminiferous tubules, rete testis, efferent ductules, epididymis, vas deferens, ejaculatory duct, urethra, external urethral orifice

Erection

nitric oxide release causes smooth muscle relaxation and arterial dilation in the corpora cavernosa; increased blood inflow compresses veins maintaining engorgement

Erectile dysfunction preventable risk factor

smoking; damages blood vessel endothelium and reduces blood flow to the penis

Scrotum

houses the testes outside the body cavity and maintains testicular temperature about 2 to 3 degrees Celsius below core body temperature

Countercurrent blood flow in scrotum

cool venous blood from the skin exchanges heat with warm arterial blood, cooling blood before it reaches the testes

Cremaster muscle

skeletal muscle that pulls the testes closer to the body in cold conditions to conserve heat

Dartos muscle

smooth muscle in the scrotal wall that wrinkles the scrotum in cold to reduce surface area and conserve heat

Leydig cells

located between seminiferous tubules; produce testosterone in response to LH

Sertoli cells

located within seminiferous tubules; nourish and regulate sperm development; produce inhibin and respond to FSH

Spermatogonia

stem cells lining the seminiferous tubules that undergo mitosis and meiosis to produce sperm

Spermatogenesis meiosis

one spermatogonium produces 4 haploid spermatids, each maturing into a functional sperm cell

Sperm head

contains the haploid nucleus with genetic material

Acrosome

cap on the sperm head containing enzymes that digest the zona pellucida of the egg during fertilization

Sperm midpiece

packed with mitochondria that produce ATP for flagellar movement

Flagellum

tail that propels the sperm via whip-like motion

Sperm DNA damage

caused by ionizing radiation, chemical toxins, smoking, elevated temperature, and reactive oxygen species

Epididymis

site where sperm gain motility and the ability to fertilize an egg

Hormones for sperm production

GnRH from the hypothalamus stimulates FSH and LH from the anterior pituitary; FSH acts on Sertoli cells; LH stimulates Leydig cells to produce testosterone; testosterone drives spermatogenesis

Female reproductive divisions

gonads are ovaries; ducts are fallopian tubes, uterus, vagina; external genitalia are labia and clitoris; accessory glands are greater vestibular glands

Wolffian ducts

embryonic ducts that develop into male internal reproductive structures in the presence of testosterone; regress in female development

Mullerian ducts

embryonic ducts that develop into the fallopian tubes, uterus, and upper vagina; regress in male development due to anti-Mullerian hormone

Myometrium

thick smooth muscle layer of the uterus that contracts during menstruation and childbirth

Endometrium

inner glandular lining of the uterus; site of implantation; consists of stratum basalis and stratum functionalis

Stratum basalis

deep permanent layer of the endometrium that is not shed during menstruation; regenerates the stratum functionalis

Stratum functionalis

superficial endometrial layer that thickens under estrogen, becomes secretory under progesterone, and is shed during menstruation

Fibroids

benign smooth muscle tumors of the myometrium that can cause heavy bleeding and pelvic pressure

Implantation timing

occurs approximately 6 to 10 days after ovulation when the stratum functionalis is thickened and secretory

Endometriosis

endometrial-like tissue growing outside the uterus; associated with retrograde menstruation, immune dysfunction, and genetic factors; can impair fertility

Site of fertilization

normally occurs in the ampulla of the fallopian tube

Primary follicle

early ovarian follicle containing a primary oocyte surrounded by a single layer of granulosa cells

Mature Graafian follicle

large fluid-filled follicle containing a secondary oocyte just before ovulation; granulosa cells produce estrogen

Granulosa cells

cells surrounding the oocyte in the follicle that produce estrogen and support oocyte development

Corpus luteum

structure formed from the ruptured follicle after ovulation; produces progesterone and estrogen to maintain the endometrium

Corpus albicans

fibrous scar tissue remaining after the corpus luteum degenerates when pregnancy does not occur

Ovulation

LH surge causes the mature follicle to rupture and release the secondary oocyte into the fallopian tube

Oogenesis meiosis

one oogonium produces 1 mature egg and 2 to 3 non-functional polar bodies; meiosis I completes before birth, meiosis II completes at fertilization

Polar bodies

small non-functional cells produced during oogenesis due to unequal cytokinesis

Oocyte maturation

meiosis II is only completed upon fertilization by a sperm cell

Oogonia decline

peak before birth then decline steeply; unlike spermatogonia, they are not replenished; essentially none remain by menopause

PCOS

polycystic ovary syndrome; characterized by irregular periods, elevated androgens, and multiple small follicles; treated with hormonal contraceptives, metformin, or lifestyle changes; associated with elevated LH and androgens from the ovaries and adrenal glands

Premature ovarian failure

intermittent loss of ovarian function before age 40 with possible remaining fertility; distinct from early menopause which is a permanent cessation

Early follicular phase

low estrogen and progesterone; rising FSH stimulates follicle growth and estrogen production

Late follicular phase

rising estrogen switches to positive feedback, triggering the LH surge and ovulation

LH surge

spike in LH from the anterior pituitary that triggers ovulation and formation of the corpus luteum

Luteal phase

corpus luteum produces high progesterone and moderate estrogen; endometrium becomes secretory; FSH and LH are suppressed

Menstruation trigger

degeneration of the corpus luteum causes progesterone and estrogen to fall, causing the stratum functionalis to shed