AIM: How does excretion in humans remove harmful

wastes?

The Hard-working Kidneys

• The two kidneys in the body receive between 1100 – 2000 liters (1160 – 2100 quarts or 500 gallons) of blood per day –about the volume of a car!

• Because the body has only about 5.6 liters of blood, your blood runs through the kidneys to be cleaned about once every four minutes.

How is the circulatory system connected to the excretory

system?

•The circulatory system transports the metabolic wastes from the body cells to the various excretory organs

How is the circulatory system connected to the excretory

system?

What is the life process of excretion?

• The removal of metabolic wastes produced by the body cells

How is excretion different from egestion?

• Egestion – the removal of the wastes of digestion – FECES

What are the five major waste products produced by your cells?

• Carbon Dioxide

• Water

• Salts (minerals)

• Urea

• Heat

How do these wastes move from the body cells to your excretory

system organs?

• The Circulatory System!

What are the major organs of the Excretory System?

• Kidney

• Skin

• Lungs

• Liver

How does the Skin aid in the removal of wastes?

• Perspiration: Gets rid of water, salt, and heat

• Has 2 to 5 million sweat glands

Sweat Gland Blood Vessels

How do the Lungs aid in the removal of wastes?

• Exhalation• Excretes water, CO2, and heat

How do the Kidneys aid in the removal of wastes?

• Produce urine and regulate water/salt balance in the blood.

• **major organ of the excretory system**

What is the major filtering unit of the kidney?

Each kidney is made of 1 million nephrons to filter the blood

The

Nephron

Description/Function

A Tiny ball of capillaries located at the beginning of each nephron (site of filtration)

B Cup-shaped portion of the nephron that surrounds the glomerulous (site of filtration)

C Site of Reabsorption and Secretion

D All remaining substances in the nephron enter here; Filtrate is now called Urine (Excretion)

E Transports unfiltered blood to the kidney; enables diffusion/active transport of substances into/out of nephron; Transports filtered blood back to the heart

Glomerulous A

B

DE

C

Bowman’s Capsule

Loop Of Henle

Collecting Duct

Blood Vessels

The Nephron

NephronBlood Processing:1)Filtration: Arteries transport blood to the

kidney (nephron)Urea, water, Glucose, and

salts (minerals) are filtered out by diffusion/active transport

No!! Way too Big!!!

Will blood cells and proteins be filtered into the nephron?

NephronBlood Processing:1)Reabsorption: Substances still needed by the

body are removed from the filtrate and reenter the blood via diffusion/active transport

Ex: glucose, water, minerals (NOT urea)

Nephron

Blood Processing:

3)Secretion:Kidneys remove certain

substances from the blood and add them to the filtrate.

Ex: Salts, Water

Nephron

Blood Processing:

4)Excretion:Urine has been formed! Will

be moved to the bladder to be excreted from the body

The Nephron

The Nephron

B

C D

A

F

E

What is urine?•The sterile fluid produced by the kidneys

•Mostly water but contains urea and salts

How does the LIVER aid in the removal of wastes?

•Produces urea from breaking down amino acids (ammonia to urea)

What are the major organs of the urinary system?

• Kidneys – produce urine

• Ureters – carries urine from

the kidneys to bladder

• Bladder – stores urine

• Urethra – releases the urine

The Urinary System

How does our excretory system help maintain homeostasis?

• Temperature balance

• Water balance

• Waste balance

Diabetes InsipidusWhat is it?Excretion of large amounts of watery urineUnquenchable thirst

What Causes It?Kidney is not reabsorbing waterBack into the bloodstream

How do you treat it?Medicine

Kidney Stones

Kidney Stones

What is it?Urine is extremely concentrated forming crystallized stones which can block the urinary tract

What Causes It?Not drinking enough water to dilute the minerals/salts being filtered out

How do you treat it?Some pass through the urinary tract, surgery, shock wave therapy

Shock Wave Therapy

Who gets kidney stones?• For unknown reasons, the number of people in

the United States with kidney stones has been increasing over the past 20 years.

• White Americans are more prone to develop kidney stones than African Americans.

• Stones occur more frequently in men. • Kidney stones strike most typically between the

ages of 20 and 40. • Once a person gets more than one stone, others

are likely to develop.

Kidney Failure

What is it?Low rate of filtration; nephron’s are not working properly in both kidneys

What Causes It?Traumatic injury, Drugs/Toxins, Infection, high blood pressure, and diabetes

How do you treat it?Dialysis; Kidney Transplant

Dialysis