Unit 6 Urinary System

Functions Removes unwanted waste products from blood Return materials to the blood Regulate BP Regulate Blood pH Activate Vitamin D3 Secrete Erythropoetin

Kidneys – 2 [PAIR] Location: retroperitoneal – on post. abdominal wall ~right is lower than left [pushed down by liver] Shape – kidney bean Size – of your fist

External Structure 3 outer layers 1. renal capsule – surface of the kidney 2. adipose capsule – fatty tissue that surrounds the kidneys 3. renal fascia – membrane that covers the posterior abdominal wall and anchors kidney

INTERNAL STRUCTURES Renal Artery- supplies blood to the kidney from aorta Renal Vein- returns blood to IVC Ureter- tubes that lead from kidney to bladder Hilum- opening in kidney for vessels to travel through Renal Pelvis- fully expanded upper end of ureter

Renal Artery Renal Vein

3 inner regions Pelvis - innermost region of the kidney Medulla - middle region of the kidney, contains 8-10 r. pyramids, r. column in between Cortex - outer region of the kidney, r. column is cortex tissue, also

Pyramids - the base of the pyramid borders the cortex; the tip (apex/ papillae) points to a minor calyx (small funnel). several (2-4) minor calyces form a major calyx

Nephrons - functional unit of the kidney - 1 million, exist in both cortex and medulla 2 parts - Renal corpuscle (cortex) and renal tubule   Corpuscle - consists of glomerular (Bowman’s) capsule and glomerulus (literally means tiny ball of yarn)

How Blood travels through the Kidney Blood Supply - Renal artery (from abdominal aorta) – eventually branches into the afferent arterioles (into nephron) Blood flow through nephron - arrives via afferent arteriole into glomerulus (capillary network), which is contained within the Glomerular/Bowman’s Capsule

In B.Capsule, the blood goes into the efferent arteriole efferent is narrower than afferent., thus increased pressure forces material (fluid, solutes) out of the blood and into the B Capsular space material is called filtrate – it will eventually become urine (blood drainage is by a reverse system, efferent arteriole eventually leads to renal vein - to inf. vena cava.)

Glomerulus has openings ( pores), which allows filtrate to escape from the blood B. Capsule wall has specialized cells called podocytes (foot cell) Podocytes form filtration slits – to help limit the type and amount of filtrate produced

Bowman’s capsule - drains into the Renal tubule Renal tubule – starts at proximal convoluted tubule, which is joined to B capsule descends into medulla and ascends back into cortex via Nephron loop (Loop of Henle). coils into distal convoluted tubule - then collecting duct

By the time filtrate reaches the collecting duct, it is urine. Urine travels through collecting duct, through the pyramids to the papillae, to the calyx