Excretion System

Question 1

Define Excretion

Answer 1

The removal of metabolic wastes from the body.

Question 2

Define Homeostasis

Answer 2

The maintenance of a constant internal environment of the body

Question 3

A function of the excretory system

Answer 3

Keeping a constant body temperature, fluid balance and salt balance.

Question 4

How does the excretory system play a role in homeostasis?

Answer 4

It keeps the body suitable for enzyme-controlled reactions.

Question 5

What is an endotherm? Give an example.

Answer 5

Endotherms - Animals that make their own heat and maintain a constant body temperature. (E.g Mammals and Humans)

Question 6

What is an ectotherm? Give an example.

Answer 6

Body temperature varies with environments and temperature. They gain or lose heat, depending on the external environment. (E.g. Fish)

Question 7

What are the functions of the skin?

Answer 7

1. Protection -
   i) Epidermis protects against damage,
   ii) Dermis protects internal organs.
   iii) Melanin protects against UV rays, which cause skin cancer.
2. Excretion - Sweating
3. Temperature regulation.

Question 8

What happens to the human body when it is cold?

Answer 8

i) The hairs on our arms stand up, which traps warm air for insulation, helping keep the body warm.
ii) Blood vessels contract, this retains heat.
iii) We shiver which produces heat and raises our temperature.

Question 9

What happens to the human body when it gets warm?

Answer 9

i) We sweat, which cools the body as it evaporates.

ii) Blood vessels dilate which increases heat loss.

Question 10

Organs of Excretion and what they excrete.

Answer 10

Lungs - CO2 and H20
Kidneys- Urea, Uric Acid, Excess water and salts.
Skin - Salts, water and uric acids.

Question 11

The function of the kidneys

Answer 11

i) Excretion of urea, excess salts and water
ii) Controls water and salt concentration of the body
iii) Controls the PH of body fluids.

Question 12

Location of the kidneys…

Answer 12

Below the diaphragm, small of the back

Question 13

Pathway of Urine from the kidney to the urethra

Answer 13

Kidney - Ureter - Bladder - Urethra

Question 14

How does the kidney make urine?

Answer 14

• Blood enters the kidneys through the renal arteries.
• The kidneys filter waste and useful materials from the blood.
• Useful materials are reabsorbed from the kidneys back into the blood.
• Urine is formed in the kidney and flows to the bladder through the Ureters.
• Blood leaves the kidneys in the renal veins.

Question 15

What are Nephrons?

Answer 15

Structures in the kidney that make urine. Each kidney has over 1 million.

Question 16

3 process in Urine Production

Answer 16

Filtration - in Glomerulus
Reabsorption - PCT, Loop of Henle, DCT, and collecting ducts
Secretion - In pelvis

Question 17

3 process in Urine Production

Answer 17

Filtration - in Glomerulus
Reabsorption - PCT, Loop of Henle, DCT, and collecting ducts
Secretion - In the pelvis

Question 18

Describe Filtration

Answer 18

Takes place in the Glomerulus. Glucose, amino acids, vitamins, urea, and salts are filtered out of the blood into the

Question 19

Describe Reabsorbtion.

Answer 19

(Substances taken from the filtrate back into the blood.)

In the PCT, water, most salts and other useful substances, are reabsorbed by diffusion and transported by the blood.

Loop of Henle, Distal Tubule, Collecting duct all reabsorb water.

Question 20

What happens to urea?

Answer 20

It is not reabsorbed back into the blood

Question 21

What forms urine, and where does it go?

Answer 21

Urea, water and salt all form urine, and it passes into the collecting duct.

Question 22

Define Osmoregulation

Answer 22

It is an example of Homeostasis. A hormone called ADH controls the volume of water reabsorbed in the collecting ducts.

Question 23

Where is ADH produced?

Answer 23

The Pituitary Gland

Question 24

What is secretion?

Answer 24

The release of urine from the urethra.

Question 25

What is the difference between the ureter and urethra?

Answer 25

Ureter - Brings urine to the bladder

Urethra - Releases Urine

Question 26

What is the difference between the kidney and the bladder?

Answer 26

Kidney- Makes Urine

Bladder- Holds Urine

Question 27

What part of the brain detects changes in our temperature?

Answer 27

Hypothalamus

Question 28

The concentration of glucose is the same in plasma and glomerular filtrate, why?

Answer 28

Glomerular Filtrate is plasma without large proteins.

Question 29

What is plasma?

Answer 29

The largest part of our blood, contains, Water (90%), Proteins, (7%), and Dissolved Materials (3%)

Question 30

What is Glomerular Filtrate?

Answer 30

Plasma without large proteins.

Question 31

In what part of the nephron does filtration take place?

Answer 31

Glomerulus

Question 32

In what part of the nephron does reabsorption of amino acids take place?

Answer 32

Proximal Convoluted Tubule

Question 33

Name the parts of the Nephron.

Answer 33

Afferent arteriole

Question 34

Osmosis Experiment

Answer 34

1. Soften 2 strips of visking tubing in water
2. Tie a knot at one end of each strip
3. Fill one piece of tubing half way with sucrose solution (80% sucrose, 20% water) and the other with distilled water (100% water). This is the control
4. Get rid of air from the tubs, and tie a knot at the open end
5. Wash off any remaining sucrose solution on the outside of tubes, then pat dry.
6. Record the turgidity of each tube, and record the mass of each tube
7. Suspend each tube in distilled water for 20 mins. After 20 mins remove from the water and dry them
8. Record the turgidity of each tube and the mass of each tube. Compare with before the experiment.