5.1.2 excretion as an example of homeostatic control

Question 1

What is excretion?

Answer 1

Excretion is the removal of waste products of metabolism from the body

Question 2

What is metabolism?

Answer 2

All the chemical reactions that happen in your cells make up your metabolism
- convert food and drink into energy

Question 3

What does metabolism produce?

Answer 3

Metabolism produces waste products

Question 4

What are waste products?

Answer 4

Substances that arent needed by the cells

Question 5

What waste products does metabolism produce?

Answer 5

1- carbon dioxide
2- Nitrogenous (nitrogen-containing) waste

Question 6

Why is it so important to remove these metabolic waste products from our body?

Answer 6

Many of these products are toxic, a build up of them in the body would cause damage EG: affecting other metabolic reactions

Question 7

How does excreting waste products from the body affect our metabolism and homeostasis?

Answer 7

Excreting waste products from the body maintains normal metabolism.

It also maintains homeostasis by helping to keep the levels of certain substances in the blood roughly constant

Question 8

What are the functions of the liver?

Answer 8

1- Excess amino acids are broken down by the liver

2- The liver removes other harmful substances from the blood - detoxification

3- The liver stores glycogen

Question 9

Where do we get amino acids in our body from?

Answer 9

One of the livers most important roles is getting rid of excess amino acids produced by eating and digesting proteins

Question 10

Why is excess amino acids broken down by the liver?

Answer 10

Amino acids contain nitrogen in there amino groups and nitrogenous waste can not usually be stored by the body. This means that amino acids are and can be damaging to the body so they either must be
1) USED by the body (eg: making proteins)
OR
2) To be broken down and excreted

Question 11

How are amino acids get broken down by the liver?

Answer 11

ORTHITHINE CYCLE
The amino group gets removed from the amino acid which leaves us with ammonia and organic acids … this process is called DEAMINATION

Question 12

What happens in the ornithine cycle?

Answer 12

Urea is formed from ammonia reacting with CO2

Question 13

Other than amino acids, what other harmful substances does the liver breakdown?

Answer 13

Alcohol
Drugs
Unwanted hormones

Question 14

What happens to products like alcohol, drugs and unwanted hormones in the body in the liver ? Process name..

Answer 14

DETOXIFICATION
- They are broken down into less harmful compounds that can then be excreted from the body

Question 15

What are the 4 veins/arteries/ducts connected to the liver?

Answer 15

1- Hepatic vein
2- Hepatic artery
3- Hepatic portal vein
4- Bile duct

Question 16

What does the hepatic artery do?

Answer 16

Hepatic artery supplies the liver with oxygenated blood from the heart so that the liver has a good supply of oxygen for respiration providing plenty of oxygen for respiration, providing plenty of energy

Question 17

What does the hepatic vein do?

Answer 17

Takes deoxygenated blood away from the liver

Question 18

What does the hepatic portal vein do?

Answer 18

brings blood from the small intestine so its rich in the products of digestion

Question 19

What does the bile duct do?

Answer 19

Takes bile to the gall bladder to be stored

Question 20

What is bile?

Answer 20

A su`qwbstance produced by the liver to emulsify fats

Question 21

Look at an image of a stained section of liver tissues

Question 22

What are 2 functions of the kidneys?

Answer 22

1- Excrete waste products EG: urea produced by the liver

2- Regulate water potential in the blood

Question 23

Where does blood enter the nephron from?

Answer 23

Renal artery

Question 24

What are nephrons and how many are there in each kidney?

Answer 24

Nephrons are long tubules along with bundles of capillaries where the blood is filtered … one million in each kidney

Question 25

After blood enters from the renal artery where does it go?

Answer 25

To the afferent arteriole

Question 26

What happens to the afferent arteriole?

Answer 26

It splits into a structure called a glomerulus

Question 27

What is a glomerulus?

Answer 27

A bundle of capillaries looped looped inside a hollow ball

Question 28

What is the hollow ball that the glomerulus is in called?

Answer 28

Bowmans capsule

Question 29

What process happens at the Bowmans capsule ?

Answer 29

Ultrafiltration

Question 30

What is an afferent arteriole

Answer 30

The arteriole that takes blood into each glomerulus

Question 31

What is an efferent arteriole

Answer 31

The arteriole that takes blood away from the glomerulus

Question 32

What is the difference between the afferent arteriole and the efferent arteriole in terms of size and what does this cause?

Answer 32

Efferent diameter is much smaller in size which results in a high pressure of the blood in the glomerulus

Question 33

What does the blood high pressure in the glomerulus cause?

Answer 33

The high pressure forces liquid and small molecules in the blood out of the CAPPILLARY and into the Bowmans capsule

Question 34

What three layers do the liquid and small molecules go through to get to the Bowmans capsule?

Answer 34

1- Capillary wall
2- A membrane called the “basement membrane”
3- Epithelium of the Bowmans capsule

Question 35

What are some examples of things that can not pass through to the Bowmans capsule and hence stay in the blood?

Answer 35

Proteins
Blood cells

Question 36

Now that the liquid and small molecules are in the Bowmans capsule, what are they called?

Answer 36

Filtrate

Question 37

What part of the nephron comes after the glomerulus?

Answer 37

The Proximal conjugated tubule

Question 38

What happens at the proximal conjugated tubule?

Answer 38

Selective reabsorption