Elimination of Wastes

Carbon Dioxide and Nitrogenous Wastes

Carbon Dioxide

Produced by the metabolism of foods by our cells

Pathway of CO2 in the body– Diffuses from the cells into the blood– Is carried by the plasma and RBC to the

lungs– Diffuses from the blood into the lungs– Leaves the body

The lungs have two major roles in the body– Remove carbon dioxide– Replenished oxygen– Their ability to do these two important

functions are affected by: Being overweight Poor physical health Tobacco or drug use

Respiratory Rate

Your respiratory rate will vary depending on your level of physical activity– The rate slows when you are at rest– It speeds up when you are active and

the body needs more oxygen brought in AND needs more carbon dioxide removed

Cellular respiration, carbon dioxide level and

respiratory rate during strenuous exercise:

1. Increased demand for energy2. Cells metabolize nutrients faster

(waste product is CO2)

3. More carbon dioxide will be produced by the cells and this will enter the blood.

4. The medulla oblongata will detect the higher levels of CO2 in the blood and it will tell the chest cavity to increase respiration

5. The CO2 will be expelled from the lungs at a rate that is proportional to its concentration in the blood (heavy breathing)

It is the increased levels of carbon dioxide in the blood that increases your respiratory rate NOT the lack of oxygen.

Review Questions page 208:1 to 8

Renal Excretory System

Removes nitrogenous waste from the blood

These waste are produced when protein is broken down by the body

A small amount of the nitrogenous waste will be excreted from the body by sweating.

Parts of the Renal Excretory System

1) The kidneys2) The bladder3) The ureters4) The urethra

Function of the Kidneys

The kidneys filter the blood The main functional unit (where the

work is done) is the nephron Each kidney has nearly one million

nephrons The nephrons are in the outer layer

of the kidney

Blood enters the kidney by the renal artery.– The kidney removes wastes and any

other substances in excess in the blood– The wastes leave the kidneys through

the ureters Purified blood leaves the kidney by

the renal vein.

Stats about your kidneys:

Filter 180 litres of blood per day Produce 1 to 1.5 litres of urine Some of the water removed by the

kidneys will be reabsorbed in the renal veins. This is to counter water lose through sweating.

Substances removed by the kidneys:

Water Urea Uric acid Minerals Yellow pigments

The following are not normally removed by your kidneys and are a sign of trouble:– Glucose– Red blood cells– ProteinSee your doctor!!!!

Normal components of purified blood:– RBC– WBC– Platelets– Lipids– Carbs– Protein– Water and minerals

Path of Nitrogenous Wastes:

Produced by the cells as protein is metabolized

Passed into the bloodstream Taken to the kidneys and removed

from the blood Ureters carry urine from kidneys to

bladder Travel from the bladder through the

urethra and out of the body

Factors Affecting the Quantity of Urine

The amount of water intake The type of food eaten The amount of water lost by

perspiration

Page 215 Questions 1 to 7 Page 218-220 Questions 1 to 8 Worksheets – Complete all sections