Homeostasis and control 5.1 - 5.2

Question 1

What is homeostasis?

Answer 1

Maintain a constant environment within the body despite internal and external changing environments

Question 2

How does information pass from a stimulus to a response?

Answer 2

Stimulus
Receptors
Processor
Effector
Response

Question 3

What receptors detect changes in temperature?

Answer 3

Thermoreceptors

Question 4

Name three effectors?

Answer 4

Muscle cells
Gland Cells
Liver Cells

Question 5

What is he difference between type 1 and type 2 diabetes?

Answer 5

Type 1
Cannot produce insulin
Type 2
Hepatic cells have become insulin resistant

Question 6

Explain negative feedback in relation to blood glucose levels

Answer 6

If receptors in the pancreas detect levels too low:

• glucagon is produced
• increased conversion of glycogen in the liver into glucose

If receptors in the pancreas detect levels too high

• Insulin is produced
• increased conversion of glucose into glycogen by hepatic cells in the liver

Question 7

Why must excess amino acids be excreted?

Answer 7

The Amino group is alkaline, so a build-up of amino acids will cause the blood pH to rise to dangerous levels, causing proteins to be denatured.

Therefore, excess amino acids must be excreted.

Question 8

Why are amino acids not excreted whole?

Answer 8

As this would mean lots of chemical energy would be wasted, so the keto acid is removed first.

Question 9

What happens to the keto acid when it is removed during deamination?

Answer 9

Can enter the Krebs cycle and be used for respiration.

Question 10

What is deamination?

Answer 10

The removal of the amine group from the amino acid to make ammonia + keto acid.

Question 11

What happens to the ammonia once it removed from the amino acid?

Answer 11

It is turned into urea via the ornithine cycle.

Question 12

What is the word equation for the ornithine cyle?

Answer 12

CO2 + 2NH3 -> (NH2)2CO + H20

Question 13

Outline the ornithine cycle

Answer 13

ornithine –> Citrulline –> Arginine