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Anatomy & Physiology

Explore the anatomy and physiology of the urinary system, focusing on kidney functions, nephron structures, hormonal regulation, and bladder function. Understand urine formation, hormone impact, and male reproductive system intricacies.

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Anatomy & Physiology

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  1. Anatomy & Physiology Urinary & Reproductive System Unit X

  2. Urinary Terms Renal – kidney Nephrology – study of kidney function Urology – study of urinary system

  3. Kidneys(located on posterior wall) Structures: -Renal cortex – outer region • Projects to inner region as renal columns that separate the renal pyramids - Renal medulla – inner region • Forms renal pyramids Calyces – cuplike units -Renal pelvis • Collects urine made • Upper end of the ureters

  4. Kidney Functions • Excrete waste • Regulate blood volume • Regulate electrolytes • Regulate acid-base balance • Regulate BP • Regulate RBC production

  5. Nephron Unit - Tubule Structures • Bowman’s capsule • C-shaped structure partially surrounding glomeruli • Proximal convoluted tubule • Coiled tubule; extension of Bowman’s capsule • Loop of Henle • Descending & ascending branch • Distal convoluted tubule • Collecting ducts • Several merging distal convoluted tubules

  6. Nephron Unit – Vascular Structures • Arterioles • Afferent → to the glomerulus • Efferent → away from the glomerulus • Glomerulus(i) – cluster(s) of capillaries • Peritubular capillaries – surrounds the renal tubules; returns back to venules, vein, renal vein

  7. Kidney Blood Pathway

  8. Urine Formation Processes • Glomeruli filtrate • H₂O & dissolved substances of Na⁺, K⁺, Cl⁻, glucose, uric acid, creatine; NO protein • Filtration occurs because of ↑ pressure in glomeruli driving substances to low pressure in Bowman’s

  9. Urine Formation Processes • Tubular reabsorption • From tubules back into peritubular capillaries; mostly @ proximal convoluted tubules • Kidneys decide type & amt. • Achieved through active transport (pumping Na⁺ from the tubules) OR passive transport (where Na⁺ goes, H₂O follows); also hormones • Tubular secretions • Small amt. of substances move from capillaries into the tubules

  10. Antidiuretic Hormone (ADH) Released from posterior pituitary gland Stimulates collecting ducts to allow H₂O reabsorption to peritubular capillaries Stimulus comes from low blood volume

  11. Aldosterone Mineralcorticoid Secreted by the adrenal cortex after stimulation by ACTH Stimulates distal tubule to reabsorb Na⁺ & H₂O = expanding blood volume & eliminates K⁺ in the urine Released in response to the enzyme renin

  12. Renin-Angiotensin-Aldosterone System • Juxtaglomerular apparatus (JGA): specialized cells in the afferent arterioles • Renin: enzyme released from the JGA when blood volume or BP ↓ • Angiotensinogen • Inactive form located in liver • Is activated by renin to convert to angiotensin I • Converting enzyme • In blood • Converts angiotensin I to angiotensin II

  13. Renin-Angiotensin-Aldosterone • Angiotensin II • Stimulates release of aldosterone • Also is a vasopressor

  14. Urine Composition Mostly H₂O, waste, electrolytes 1500 mL/day pH: 5.0 – 8.0 (usually acidic) Characteristic odor Specific gravity: 1.001 – 1.030

  15. Urinary Structures – Ureters • Carries urine from renal pelvis to bladder

  16. Urinary Structures – Bladder • Temporary urine storage (rugae) • Mucosa, submucosa, muscle, serosa • Internal sphincter - at exit of bladder • Smooth muscle; involuntary • External sphincter – below internal • Skeletal muscle; voluntary • Urination, micturition, void • Micturition reflex: full bladder; sensory nerves to spinal cord; motor response back to bladder; bladder wall contracts & internal sphincter relaxes

  17. Urethra • Carries urine from bladder to outside (meatus) • Lined with mucous membrane • Length varies

  18. Male Reproductive System Functions Produces, nourishes, transports sperm Deposits sperm within female reproductive tract Secretes hormones that determine secondary sex characteristics

  19. Internal Male Structures & Functions - Testes • Male gonad • Produce sperm & secrete testosterone • Begins developing within abdominopelvic cavity & descends into scrotum to live at lower than body temperature environment • Made of lobules • Seminiferous tubules • Sperm production • Interstitial cells • Secrete the androgens • Spermatogenesis • Sperm formation • Primary spermatocyte undergoes meiosis

  20. Sperm Head: primarily a nucleus; helps to penetrate egg Body: mid piece; contains mitochondria Tail: flagellum; mobility

  21. Genital Ducts • Epididymis • Tightly coiled structure sitting on top of testes; • Sperm matures here • Vas deferens • Ascend with spermatic cord into pelvic cavity, curves over bladder

  22. Genital Ducts • Ejaculatory ducts • The joining of the vas deferens with the seminal vesicles • R. & L. duct merge to join urethra • Urethra • Extends from bladder to tip of penis • Surrounded by prostate gland • Transports urine & semen

  23. AccessoryGlands • Seminal vesicles • Base of bladder • Adds a nutritious secretion to semen • Prostate gland • Encircles urethra just below the bladder • Produces alkaline secretion to neutralize vaginal acid & ↑ sperm mobility • Contracts during ejaculation to move semen • Bulbourethral glands • Cowper’s glands • Secrete lubricating mucus into distal urethra

  24. Semen Functions Nourishes sperm Transports sperm Lubricates lower structures of reproductive tract

  25. Male External GenitalsPenis • Shaft • 3 columns of erectile tissue • Accumulation of blood causes erection • Glans penis: distal end • Urinary meatus: penetrates the glans • Prepuce • Foreskin; covers the glans • Function • Expels urine & is intercourse organ

  26. Male External GenitalsScrotum • Sac that holds the testes

  27. Testosterone • Primary sex characteristics • Testes & penis size • Secondary sex characteristics • Hair growth & distribution • ↓ voice • Musculoskeletal growth • ↑ activity of skin glands

  28. Male Hormone System • Hypothalamus – releasing hormones → anterior pituitary gland = gonadotropins • FSH • Stimulates spermatogenic cells = sensitivity ↑ to testosterone • LH • Stimulates interstitial cells to secrete testosterone • Negative feedback effect • As plasma levels of testosterone ↑, ant. pituitary ↓ LH output

  29. Female Reproductive Functions • Produces ova • Secretes hormones • Nurtures & protects a developing fetus during 9 months of pregnancy

  30. Internal Structures & Functions Ovaries – female gonad • Egg development – the ovarian follicle (a tiny saclike structure; MANY) • Each follicle contains an immature oocyte (egg) & surrounding follicular cells • Oocyte → meiosis • Follicular cells → estrogen • Mature ovarian follicle = graafian follicle

  31. OVULATION eject 1 egg/month from surface • Egg swept up by the fimbriae of the fallopian tubes • Follicular cells remain in the ovary; become corpus luteum (gland structure) → progesterone • Corpus luteum = YELLOW BODY • Corpus albicans= WHITE BODY

  32. Internal Structures Fallopian Tubes • Oviduct, uterine tubes • Site of fertilization • Transports egg to uterus • Infundibulum – distal tube

  33. Internal Structures Uterus • Fundus • Upper dome shape part • Body • Center • Cervix • Long narrow region • Layers • Epimetrium (outer) • Myometrium (muscle) • Endometrium (inner)

  34. Internal Structure Vagina • Part of birth canal • Receives penis during intercourse

  35. External Female GenitaliaVulva • Labia majora & minora • Prevents drying of the mucous membrane • Clitoris • Erectile tissue • Vestibule • Between labia minora • Contains urethral & vaginal openings • Bartholin’s glands • Vestibular glands near the vaginal opening; secrete mucus • Perineum • Between vaginal & anus

  36. Female Hormones • Estrogen – secreted by follicular cells • Promotes egg maturation • Secondary sex characteristics • reproductive organs develop • breast development • fat distribution • pelvis widens • menstrual cycle participation • closes epiphyseal disc • Progesterone – secreted by corpus luteum • Menstrual cycle participation • Assist to maintain pregnancy • Breast preparation for milk production MENSES= CYCLIC VARIATION IN HORMONE SECRETION

  37. Ovarian Cycle Follicular phase • Hypothalamus → releasing hormones → ant. pituitary gland → gonadotropins • FSH → development of ovarian follicle which the follicular cells secrete estrogen (which dominates this phase) • LH → ovulation @ about 14 days & starts luteal phase

  38. Ovarian Cycle Luteal phase • Dominated by the progesterone secreted by the corpus luteum • ↑ levels of estrogen & progesterone • Prevent release of gonadotropins • Build up endometrial lining (progesterone) in preparation for pregnancy

  39. Uterine Cycle • Menstrual phase • Shedding of endometrial lining due to ↓ in ovarian hormones when corpus luteum dies • Proliferative phase • Buildup of endometrial lining after menstruation due to estrogen secretion • Secretory phase • Endometrial thickening from progesterone secretion

  40. Pregnant State Human chorionic gonadotropin (hCG) • Will be secreted by the trophoblastic cells of the embryo to maintain corpeus luteum to continue secreting hormones to maintain endometrial tissue

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