Functions of the Excretory System

• Your body must eliminate wastes to remain healthy.

• These systems function together as parts of your excretory system.

• The urinary system rids the blood of wastes produced by the cells.

• The urinary system also controls blood volume by removing excess water produced by body cells during respiration.

• Gets rid of excess salts

The Urinary / Excretory System The Urinary / Excretory System

Organs of the Urinary System

• The main organs of the urinary system are two bean-shaped kidneys.

• The kidneys filter blood that contains wastes collected from cells.

• It is made up of about 1 million tiny filtering units called nephrons (NEF rahnz).

Narrow part of pyramid

Renal pelvis w/ pyramid

Inner layer

Outer layer

Triangle shape in medulla

Drains urine from calyx

Expansion of upper end of ureter

Clean deO2

Dirty & O2

Microscopic Structure

Each kidney > 1 million Nephrons Basic unit of S&F of kidney

3 Steps in Urine Formation in Nephrons

Filtration in Renal Copuscle

Reabsorption between tubules and peritubular capillaries (both 1 cell thick)

99% H2O by osmosis, glucose AT, Na+ based on intake

Secretion opposite of reabsorption, substances move from peritubular capillaries into tubules (Ex. NH3 diffusion)

Urine voided from bladder urethra in micturition

Regulating Fluid Levels

• The hypothalamus constantly monitors the amount of water in the blood.

• When the brain detects too much water in the blood, the hypothalamus releases a lesser amount of ADH (anti diuretic hormone)

• This signals the kidneys to return less water to the blood and increase the amount of wastewater, called urine, that is excreted.

• Alcohol & caffeine ADH levels

What does this do to urine volume, why?

• Nicotine ’s ADH levels

• What does this do to urine volume, why?

Urinary Diseases and Disorders• Waste products that are not removed build

up and act as poisons in body cells.

• Water that normally is removed from body tissues accumulates and causes swelling of the ankles and feet.

• Without excretion, an imbalance of salts occurs. If the balance isn’t restored, the kidneys and other organs can be damaged.

• If not treated Death :(

Dialysis

• A person who has only one kidney still can live normally.

• The remaining kidney increases in size and works harder to make up for the loss of the other kidney.

• If both kidneys fail, the person will need to have his or her flood filtered by an artificial kidney machine in a process called dialysis or have a kidney transplant.