The Excretory System

Excretory System

• As cells perform the chemical activities that keep you alive, waste products such as carbon dioxide and ammonia are formed.

• To maintain homeostasis and keep you healthy, they must be removed.

Facts!

Functions of Excretory System

• Rids blood of wastes like urea, ammonia, and carbon dioxide.

• Controls blood volume by removing extra water produced by cells.

• Balances salts and water so cells can function properly.

Excretory System• Organs

– kidneys– ureters– urinary bladder– urethra– lungs– skin

sweat glands

lungs

Organs of Excretion

There are other organs in our body that can excrete substances

• lungs – carbon dioxide and water vapor are exhaled

• skin – excess salt is released when you sweat.

Organs of the Excretory System• kidneys –filters

blood and eliminates cellular waste. Returns salt, ions and glucose to the blood.

Organs of the Excretory System

Organs of the Excretory System• ureters – two

narrow tubes that urine flows through to get to the bladder.

Organs of the Excretory System• urinary bladder

– sac-like muscular organ that stores urine.

Organs of the Excretory System• urethra – tube that urine travels to

leave the body.

The Filtering Process• Your cells have to maintain a certain

level of water and salt to function properly.

• nephrons – tiny structures that filter blood in the kidneys.

Vocabulary Word!

Filtering Out Waste

• After entering the kidneys, blood flows through smaller and smaller arteries.

• The blood eventually reaches a cluster of capillaries called nephrons.

• In the nephron, urea, glucose, other chemicals, and some water move out of the blood and into the nephron.

Filtering Out Waste

• Blood cells and proteins stay in the capillaries.

• Glucose, water, and small amounts of other substances are reabsorbed into the blood stream.

• Urea and other wastes stay in the nephrons.

Filtering Out Waste

• The liquid left in the tube is urine.• The urine moves down the ureters

and into the bladder.• When the bladder is full, you feel the

urge to urinate.

Filtering Summary

• 1. both wastes and needed materials are

filtered out of the blood• 2. the needed material is returned to

the blood• 3. the waste is eliminated in the

urine

Analyzing Urine

• Some medical problems can be found by testing urine

• Glucose – diabetes• Protein – kidney failure• Drug residue – drug abuse

Body systems that work with the excretory system;• circulatory system to carry

waste to the kidneys.• respiratory system to remove

carbon dioxide.• integumentary system to

remove salt.

Comparing Cells to Body

What cell organelle helps to break down waste?

What cell organelle packages waste?

golgi body

lysosomes