Urinary system

Lab 7

Announcements

• Urinary system

• Lab Practical Week after Spring Break

• Practical Review this Sunday 23rd at 3-5 pm

Functions of Urinary System

• Kidneys carry out four functions– Filter nitrogenous wastes, toxins, ions, etc. from blood

to be excreted as urine.

– Regulate volume and chemical composition of blood (water, salts, acids, bases).

– Produce regulatory enzymes.• Renin – regulates BP/ kidney function

• Erthropoeitin – stimulates RBC production from marrow.

– Metabolism of Vitamin D to active form.

Urinary System

• Two Kidneys– 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 CTP 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

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.

Urine Formation III

• 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

Countercurrent Multiplicationin the Nephron Loop

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– 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)

Dynamic Human

Visualizing the Urinary System

Intravenous pyelography

Ultrasound

Dissection

• Be able to identify layers of the kidney on human material

• Be able to locate kidneys, ureters, urinary bladder, and urethra on cat.

Next Week – Spring BreakWeek After - Practical II

• Material over lymphatic, respiratory, and urinary systems

• Review Sunday (end of break) at 3-5pm

• Remember – some questions will be based on identifying structures on the cats.