The Urinary System

Excretion- removal of waste produced during body functions Occurs through: 1.Intestine- digestive wastes, salts 2.Skin (sweat glands)- water, electrolytes 3.Lungs- carbon dioxide, water 4.Kidneys- toxins, water, N cmpds, electrolytes

Urinary System Functions A.maintain water concentration in blood B.maintain concentration of ions like Na & K C.form urine D.influence rate of secretion of hormones like ADH E.alter pH (acid- base balance) Why bother with all of these?

Basic Anatomy of the Urinary System

Gross Anatomy- KIDNEY 1.lie in retroperitoneal position 2.Fat cushion holds it in position 3.medial surface with concave hilus Not that type….

Gross Anatomy- KIDNEY 4.Cortex- outer and lighter 5.Medulla- inner and darker 1. Cortex region of kidney 2. Medulla region of kidney

Gross Anatomy- KIDNEY 6. Most of the medulla is made up of RENAL PYRAMIDS with a base facing outward and papilla facing the hilus

Gross Anatomy- KIDNEY 7. Cortical tissue dips into the medulla between the pyramids, forming RENAL COLUMNS

Gross Anatomy- KIDNEY 8. Each renal papilla juts into a cup-like CALYX –Urine leaving the renal papilla collects here before leaving the body

Gross Anatomy- KIDNEY 9. The calyces join to form the renal pelvis. It narrows as it exits the hilum to become the ureter.

Macroscopic Kidneys A. Capsule & hilus B. Renal sinus 1. renal pelvis 2. major calyces 3. minor calyces C. Renal medulla 1. renal pyramids a. papilla 2. Renal column D. Renal cortex

C. URINARY BLADDER 1.behind symphysis pubis 2.mostly smooth muscle aka detrusor muscle lined with transitional epithelium 3.3 openings: 2 from ureters and one into the urethra 4.Has valve to prevent backflow into kidney 5.Functions –urine reservoir –aided by urethra, expels urine from body

Male Urethra Female Urethra

Gross Anatomy- URETHRA 1.3 cm in females; 20 cm in males 2.Male urethra (URINE) passes through prostate gland where it is joined by 2 ejacuatory ducts (SEMEN) then travels through penis and ends at the urinary meatus at the tip of the penis. 3.In females, completely separate from vagina

4. Micturition- urination 1.Voluntary relaxation of external sphincter muscle of bladder 2.Detrusor muscle contracts 3.Parasympathetic nerve control 4.Incontinence

Microscopic Structure of the NEPHRON Filtering unit of kidney Process blood plasma Form urine 1.25 million per kidney Looks like a funnel with a long, winding stem

The Nephron The nephron is the functional unit of the kidney, responsible for the actual purification and filtration of the blood. About one million nephrons are in the cortex of each kidney.

The Glomerulus

Microscopic Structure of the NEPHRON PROXIMAL TUBULE- in cortex –Closest to BC (“proximal”) –Aka PCT (proximal convoluted tubule) –Brush border (microvilli) face lumen- increase surface area

The NEPHRON LOOP OF HENLE (LOH) Renal tubule beyond the PCT –Descending limb (thin) –Sharp turn –Ascending limb (thick) –Dips into medulla cortex medulla

THE NEPHRON DISTAL TUBULE Aka DCT (distal convoluted tubule) Beyond LOH (“distal”) Juxtaglomerular apparatus

THE NEPHRON COLLECTING DUCT –Straight tubule joined by distal tubules of several nephrons –Fuse to form papillary ducts which deliver urine to the calyces

Anatomy of Micturition & Incontinence Detrusor muscle with an External and Internal sphincter Normal capacity cc First urge to void cc CNS control –Pons - facilitates –Cerebral cortex - inhibits Harmonal effects - estrogen

Nephrolithiasis: kidney stones Supersat. of urine by stone forming constituents Freq. stone types: Calcium (most common), struvite, oxalate, uric acid Risk factors: metabolic disturbances, previous UTI, gout, genetic Incidence = 2-3% Hematuria (rarely dangerous by itself) Dangerous combo = obstruction + infection

Addison’s Disease Addison's disease occurs when the adrenal glands do not produce enough of the hormone cortisol and, in some cases, the hormone aldosterone