The Excretory system Functions of the Excretory System

The Excretory system

Functions of the Excretory System • Removal of waste products from the body

Parts of the Excretory System • Kidneys-remove waste products from the blood; maintain blood p. H; regulate water content in blood and regulates blood volume • Ureters- carries urine to the bladder from the kidneys • Bladder- sac-like organ that collects urine • Urethra-tube that allows urine to pass from the body

Parts of the Excretory System Renal Artery Kidneys Bladder Ureters Urethra

Functional Units of the Kidney • Nephrons-Cells in Kidney Tissue – Small independent processing unit – Each has its own blood supply

Filtration • Passing a liquid or gas through a filter to remove waste • Filtration of blood mainly takes place in the glomerulus (enclosed by bowman's capsule) Glomerulus

Filtration Cont. • Materials filtered from the blood are called filtrate. (water, salts, vitamins)

Reabsorption • The process in which liquid is taken back to the blood is called reabsorption. • Amino acid, fat, glucose and most water is removed from the filtrate and returned to the blood.

Reabsorption Cont. • Urine, which contains urea, excess salts and water, is concentrated in the loop of Henle. Loop of Henle

Reabsorption Cont. • Filtered blood is returned to the blood stream and urine moves to the urinary bladder through the ureters. • The bladder holds the urine until it is excreted from the body through the urethra.

Control of Kidney Function • The kidney’s job is to maintain the composition of the blood. • Kidney activity is largely controlled by the composition of the blood.

Feedback Mechanisms in the Excretory System If the amount of water in the blood is high then less water will be returned to the blood stream and more water will be secreted in the urine. Stimulus: ______ Response: ______ Feedback: ______

Feedback Mechanisms in the Excretory System If the amount of salt in the blood is high then less salt will be returned to the blood stream and more salt will be excreted in the urine. Stimulus: ______ Response: ______ Feedback: ______

Homeostasis by Machine • If kidney function is disrupted due to damage or disease serious medical problems can arise. • If one kidney is damaged or diseased a person can survive with just one. • If both kidneys are damaged one of two things need to happen for a person to be able to survive.

Homeostasis by Machine Cont. • The person can receive a kidney transplant or • The person can receive dialysis.

• Dialysis is where blood is filtered through a machine that filters out waste products and then returned to the body.