Urinary system Lab 8

Urinary System Two Kidneys Two Ureters Urinary Bladder Urethra Perform all functions except actual excretion. Two Ureters Convey urine from Kidneys to Urinary Bladder Urinary Bladder Holds Urine until excretion Urethra Conveys urine from bladder to outside of body

Complete System

Kidney general info Lie against posterior abdominal wall at level of T12-L3. Right kidney is lower than left kidney due to the shape of the liver. Lateral surface of kidney is convex while medial is concave. Concave side has a cleft – Renal Hilus Inside hilus is Renal sinus Where kidneys receive renal vessels and nerves.

Kidney External Anatomy Average size – 12cm x 6cm x 3 cm Weights 150 grams or 5 oz Surrounded by three membranes (deep to superficial) Renal capsule – fibrous barrier for kidneys. Adipose capsule – fatty tissue designed for protection / stability. Renal fascia – dense fibrous CT anchors kidneys/ adrenals/ membrane 1 and 2 to surroundings.

Kidney Anatomy Renal arteries and veins Renal cortex Renal medulla Nephron Renal pyramids (6-10) Renal papilla Calyx (ces) Renal pelvis Ureter

Kidney- External Anatomy Lateral surface- convex Medial is concave- Renal Hilum Opening to Kidney Renal Sinus Space within hilus Kidneys receive blood vessels and nerves.

Kidney Internal Anatomy I Renal arteries and veins Bring blood in and out of kidney Renal cortex Outer layer of Kidney Renal medulla Inner layer of Kidney Nephron

Kidney Internal Anatomy II Renal Pyramids Renal Columns Space between pyramids within the medula Renal Papilla Narrow end of pyramid Calyx (ces) Collecting tubes Renal Pelvis Collecting vessel prior to ureter

Human Kidney

Nephron Blood processing unit which serves to produce urine 1 million per kidney Consists of a glomerulus and tubules

Nephron: Vascular System Afferent arteriole Glomerulus Efferent arteriole Peritubular capillaries Capillary beds reabsorb in cortex Vasa recta Capillary beds reabsorb in medulla

Nephron Tubular system Glomerular Capsule Proximal convoluted tubule Loop of Henle (nephron loop) Descending limb Ascending limb Distal convoluted tubule Collecting duct

Nephron

Gross Anatomy Urinary system Kidney Nephron Dynamic Human Gross Anatomy Urinary system Kidney Nephron

Urine Formation I Glomerular filtration Water, ions, amino acids, and glucose get into capsular space from blood Proteins stay in blood – too big to leave capillaries.

Urine Formation II Proximal convoluted tubule and Peritubular capillary Na+ goes down gradient and brings glucose, amino acids, etc. back into blood stream (cotransport). Reabsorbs about 65% of filtrate.

Countercurrent Multiplication Urine Formation III Countercurrent Multiplication in the Nephron Loop Descending limb Goes into medulla - increasing salt gradient Water leaves Fluid concentrates Ascending limb Goes up toward cortex - decreasing salt gradient Na+ pumped out Fluid relatively diluted

Nephron Loop

Urine Formation IV Collecting duct Travels down into medulla Water leaves tubule and enters blood Urine becomes concentrated and enters renal papilla ADH controls water channel ADH – Antidiuretic hormone

Collecting duct

Dynamic Human Urine Formation

Micturition Ureters Urinary Bladder 25 cm long Enters on the floor of bladder Urinary Bladder Muscular sac on floor of pelvic cavity Muscle layer formed by detrusor muscle Average bladder volume is 500 ml Max capacity is 700-800 ml

Micturition Urethra Conveys urine out of body Female urethra – 3 - 4 cm Opens into external urethral oriface Lies between vaginal oriface and clitoris Male urethra – 18 cm 3 regions Prostatic urethra – 2.5 cm Membranous urethra – 0.5 cm Penile urethra – 15 cm

Micturition Reflex Bladder with >= 200 ml of urine Sensory input to parasympathetic system Contraction of detrusor muscle and relaxation of internal urethral sphincter Relaxation of external urethral sphincter

Micturition

Kidney stones A hard granule of calcium, phosphate, uric acid and protein. Form in renal pelvis and get lodged in pelvis or ureter. Caused by urinary tract infections, dehydration, pH imbalances, or an enlarged prostate gland. Treated with stone dissolving drugs, surgical removal, or lithotripsy (ultrasonic vibrations)