Chapter 15The Urinary System

Functions of the Urinary SystemFunctions of the Urinary System1. Elimination of waste

Nitrogenous wastes

Toxins

Drugs

2. Regulates homeostasis

Water balance

Electrolytes

Acid-base balance in the blood

Blood pressure

RBC production

Activation of vit. D

Organs of the Urinary systemOrgans of the Urinary system

Kidneys

Ureters

Urinary bladder

Urethra

Location of the KidneysLocation of the Kidneys

Against dorsal wall

Right lower than left

Attached to ureters, renal blood vessels, & nerves at renal hilus

Atop kidney is adrenal gland

Regions of the KidneyRegions of the Kidney

Renal cortex – outer region

Renal medulla – inside the cortex

Renal pelvis – inner collecting tube

NephronsNephrons Structural and

functional units of the kidneys

Forms urine

Main structures

a. Glomerulus

b. Renal tubule

GlomerulusGlomerulus

Glomerulus sits within a glomerular capsule (1st part of the renal tubule)

Specialized capillary bed

Arterioles on both sides (maintains high pressure)

- Large afferent arteriole

- Narrow efferent arteriole

Renal TubuleRenal Tubule Glomerular

(Bowman’s) capsule

Proximal convoluted tubule

Loop of Henle

Distal convoluted tubule

Urine FormationUrine Formation

Filtration

Reabsorption

Secretion

FiltrationFiltration Nonselective passive process

Water and solutes smaller than proteins are forced through capillary walls (Filtrate same as blood plasma)

Blood cells cannot pass out to the capillaries

Filtrate - collected in glomerular capsule and leaves via the renal tubule

ReabsorptionReabsorption Peritubular capillaries reabsorb

- Some water, Glucose, Amino acids, Ions

Some passive, most active

Most reabsorption occurs in proximal tubule

Nitrogenous waste products

- Urea

- Uric acid

- Creatinine

Excess water

Not ReabsorbedNot Reabsorbed

Secretion Secretion

Materials left in renal tubule move to ureter