THE URINARY (EXCRETORY) SYSTEM NHS – Anatomy and Physiology Dr. Smith

FUNCTION Produces and excretes urine from the body Fluid, Electrolytes and wastes are filtered from blood - VITAL Toxic levels in the blood - uremic poisoning Normally adjust output to equal input

Characteristics of URINE

LOCATION Lies above the waistline - between back muscles and peritoneum right kidney is a little lower then left - surrounded by fat 20% of blood each minute gets pumped through the kidney’s - large renal arteries

Internal Structure Cortex - outer part of kidney Medulla - inner part of kidney Pyramid - triangular divisions of the kidney Papilla - innermost end of pyramid- Minor calyx, Major calyx Pelvis - end of ureter; Calyxes- part of renal pelvis Minor calyx- from each papilla Major calyx- into renal pelvis

Microscopic Structure Nephron - functional unit of kidney ( 2 main parts renal corpuscle renal tubule

Renal Corpuscle Bowman’s capsule - top of nephron Glomerulus - small network of capillaries - blood delivered by afferent arterioles and drained by efferent arterioles

Renal Tubule Proximal convoluted tube - 1st branch tube - has several bends Loop of Henle - hairpin loop Distal convoluted tube - distal to Loop Collecting tube – distal con. Tube drains into

MAKING URINE Millions of nephrons form urine by 1. Filtration - blood pressure causes substances to move out of glomeruli and into Bowman’s capsule 2. Reabsorption - movement of substances out of renal tubes into blood capillaries where they are reabsorbed (glucose, H2O, ions) Secretion - moving undesired (not reabsorbed substances into urine

CONTROL OF MAKING URINE ADH (antidiuretic hormone) - pituitary- little or no water is removed - (urine decreasing hormone) aldosterone -adrenal- reabsorb sodium salts at a faster rate (water follows- is reasbsorbed) PH - Urine - 4.5-8.0 ABNORMAL AMOUNTS OF URINE Anuria - absence of urine Oliguria - low amounts of urine Polyuria - excess amount of urine

URETERS Long narrow tubes with an expanded upper end(renal pelvis)located inside the kidney and lined with mucous membrane (transitional epithelium). Function: to drain the urine for the renal pelvis to the urinary bladder

URINARY BLADDER an elastic muscular organ capable of great expansion it is lined with a mucous membrane (TE) arranged in rugae like stomach mucous, when it’s empty its wrinkled and when full it’s smooth, it stores urine before voiding and is responsible for voiding

URETHRA narrow tube from the urinary bladder to exterior, lined with mucous membrane the opening of the urethra to exterior is called the urinary meatus passes urine to exterior of body MALE: passage way of semen from the body

Micturition Passing of urine to the exterior of the body (VOIDING, URINATION) Reflex action up until about age 3 - then voluntary reaction 2 sphincter (muscle rings), internal and external seal off bladder. Bladder can hold 300 - 400 ml - need to urinate begins at 150mL Emptying Reflex - opening of internal sphincter - and contraction of bladder muscles

Urinary retention - kidneys produce urine - bladder cannot empty Urinary suppression - kidneys do not produce urine - bladder always empties Incontinence - voids involuntary - usually do to spinal injury – age ( normal in infants) Cystitis - bladder infection

Hemodialysis Artificial Kidney machine - usually radial artery- takes blood through a solution where dialysis can occur - usually 2,3 treatments a week CAPD - 1 to 3 liters of sterile fluid is introduced into peritoneum, allowed to perform dialysis then drained

Catheterization Insertion of a tube or catheter into the bladder via the urethra to remove urine

KIDNEY STONES Renal caculli - very painful Most are small enough to pass through system Up until present most were surgically removed NOW- possible- lithotripsy - produces ultrasonic waves that breaks up stones into smaller pieces