Aim: How does our Body’s Excretory System Maintain Bodily Homeostasis? DO NOW 1.Describe the functions of three components to your blood. 2.Why does your heart need to beat? What would happen if it stopped beating?

Excretory System Function: the removal of metabolic waste (liquid) from the body Also regulate water content of the body Q: Where do wastes travel in the body? Q: What kind of metabolic wastes will be removed from the body?

Transport Medium Wastes travel in the blood – Excess salts – Carbon dioxide – Urea (nitrogen compound) Q: What would happen if these wastes were not eliminated from the body?

Excretion The life process by which metabolic wastes are removed from the body Maintains body homeostasis

Kidneys Your body’s main excretory organ Contain filtering units called nephrons that filter the blood About the size of a clenched fist Two kidneys

Nephrons Filtering units of the kidneys Each nephron has a network of capillaries enclosed in a cup-shaped capsule 1 million in each kidney Blood enters here & filtration happens Reabsorption of important nutrients occurs back into the body After reabsorption is completed, remaining materials (urine) will get excreted from the body

Kidney & Nephron Visual

Excretion Pathway Kidneys  Ureters  Urinary Bladder  Urethra Ureters lead to the urinary bladder where urine is stored When the bladder becomes full, urine will exit the body by way of the urethra

Control of Kidney Function Q: If you do not drink large amounts of water today, how will your kidneys respond to this? Will water that you drink be excreted or reabsorbed into the blood? Q: If you eat a lot of salty food today, how will your kidneys respond to this? Will all the salt be reabsorbed into your blood?

Liver Helps in excretion – Removes nitrogen from waste amino acids – Breaks down all red blood cells – Makes chemical poisons harmless alcohol Controls level of cholesterol in blood Helps maintain body’s water balance Stores vitamins Makes bile Keeps blood sugar levels constant – Stores excess glucose in the form of a starch & releases it into the blood when needed

Make a Connection! Think of another human body system which we learned about. Q: Is there any other organ, part of another body system, which also excretes a compound?

Skin & Lungs Skin excretes excess water & salts & small amounts of urea Lungs excrete carbon dioxide

Question Which human body system(s) does the excretory system work with to maintain body homeostasis?

Brain-Pop ms/urinarysystem/ ms/urinarysystem/

Group Activity Brain-Pop Video Questions

Individual Activity On looseleaf, answer today’s AIM Hand in to teacher Aim: How does our body’s excretory system maintain bodily homeostasis?

Homework Castle Learning multiple choice questions on excretion Due: Thursday