The Urinary system

Function is to regulate the volume and composition of body fluids and to excrete liquid waste in the form of urine. Urine travels to the outside via ureters, urinary bladder, and urethra.

Kidney-

Kidneys-Location posterior abdomen beside vertebral column from level T12 to L3. Macroscopic evaluation- recognize hilum, cortex, medulla, pyramids, calyx.

Ureters-mucous inner layer, muscular middle layer, and fibrous outer layer. Propels fluids by peristalsis. Tubes which carry urine from the kidney to the bladder.

Urinary bladder-collapsible bag behind the symphysis pubis. Smooth muscle over the bag is the detrusor muscle. External sphincter is voluntary and internal sphincter is under parasympathetic control.

Urethra- carries urine out of the body. In males it also carries semen during ejaculation. It exits through the penis in males and the orifice is in front of the vagina in females.

Microscopic structure of the kidney. Discuss Bowman’s capsule with glomerulus (filtration), proximal convoluted tubule (reabsorption), descending and ascending loop of Henle (concentration/dilution), distal convoluted tubule (secretion) and collecting ducts

Male reproductive system

Primary sex organs or gonads (testes- similar in function to female ovaries)

Male anatomy—scrotum (pouch)- contains testes and epididymis, maintains intrascrotal temperature with 1) dartos muscle- smooth muscle layer in superficial fascia with wrinkles skin,2) cremaster (suspender muscle) and 3) pampiniform plexus- testicular artery surrounded by testicular vein.

Testes-produce sperm and testosterone. Albuginea (white coat) encases testes within the scrotum, dividing them into lobules. Testes are suspended by the spermatic cord (testicular artery, vein, nerve, lymphatics and ductus (vas) deferens). Each lobule contains interstitial cells of Leydig, Sertoli cells, and seminiferous tubules.

Direction of movement

Seminiferous tubules

-tubulus rectus

-rete testis

(via efferent ductules)

–epididymis (head, body, tail- about 20 days to become fertile and motile)

-ductus or vas deferens

(fluids from seminal vesicle enter here)

- ejaculatory duct-urethra in prostate gland (prostatic, membraneous, and spongy/penile) urethra

Blood supply- testicular arteries (from aorta). Veins form pampiniform plexus around arteries as testicular veins return blood to inferior vena cava.

Accessory glands

Seminal vesicles- alkaline fluid containing fructose ( fuel), ascorbic acid (prevents oxidation), and prostaglandin (decreases viscosity of cervical mucus); about 60% of semen
Prostate gland- about 30% of semen; encircles urethra below the bladder; alkaline fluid containing fibrinolysin (reverses coagulation after ejaculation), acid phosphatase (activates sperm)
Cowper’s (bulbourethral) gland-alkaline mucus released prior to ejaculation believed to neutralize traces of acidic urine.

Penis (tail) is designed to deliver sperm into female reproductive tract. Corpora cavernosa and corpus spongiosum surround urethra. Glans at distal end make be covered by the prepuce/foreskin (sometimes removed for cultural, medical, or religious reasons in a surgical procedure called circumcision)

Spermatogenesis

Spermatogonia divide into Type A (germ cells) and Type B (primary spermatocytes). Spermatocytes undergo meiosis 1 to produce and secondary spermatocyte, followed by meiosis 2 to become a spermatid. The process of spermiogenesis causes structural changes and production of spermatozoan (sperm) cells

Sperm structure- Head (genetic) has acrosome (hyaluronidase allows penetration of an egg). Midpiece behind head had fuel packets (metabolic) and the tail is responsible for locomotion (flagellum).

Sertoli/sustentacular/nurse cells-1) tight junctions separate basal and luminal compartments making the blood-testis barrier preventing immune response to sperm antigens, 2) deliver nutrients, 3) secrete testicular fluid ( sperm transport medium), 4) dispose of xs cytoplasm, 5) release androgen-binding protein, and 6) inhibin