Homeostasis

Question 1

Define what Homeostasis is?

Answer 1

Maintaining the internal environment despite external changes.

The following have to be maintained;
Body temperature
Glucose Level (Sugar)
Water Levels
Ions (Salt)
Blood Pressure

Question 2

What (3) things is Homeostasis broken down into?

Answer 2

1) Thermoregulation (Maintaining an optimal internal temperature.)

2) Osmoregulation (Controls internal water levels.)

3) Glucoregulation (The regulation of blood sugar.)

Question 3

Explain the role of the Antidiuretic Hormone (ADH)?
(Osmoregulation)

Answer 3

ADH is the hormone released by the pituitary gland into the blood stream. It signals to the kidneys how much water to reabsorb and how much to get rid of. The release of this hormone is an example of negative feedback.

Question 4

Explain the role of the Kidneys?
(Osmoregulation)

Answer 4

The kidneys control the blood plasma and makes sure that the components that make up the blood plasma are proportional. Kidneys control urea, salt, water and sugar levels.

This is how it works:
Blood plasma enters the kidneys

All the sugar is reabsorbed into the blood plasma, as well as some water and some salt.

Excess sugar and salt is expelled through the urine. Urea is also lost through the urine. Urea is made of amino acids that cannot be broken down.

Question 5

Explain what the Pancreas does?
(Glucoregulation)

Answer 5

1) Blood glucose levels are monitored and controlled by the pancreas.

2) The pancreas produces and releases different hormones depending on the blood glucose level.

Question 6

Explain what insulin does?
(Glucoregulation)

Answer 6

Insulin is released when blood glucose levels are high – the liver stores excess glucose as glycogen

Question 7

Explain what Glucagon is?
(Glucoregulation)

Answer 7

Glucagon is released when blood glucose levels are low – the liver converts stored glycogen into glucose and releases it into the blood.

Question 8

What is Negative feedback?
(Simple Version)

Answer 8

1)The reversing of a change in the internal environment

2) Change needs to be detected

3)Change must be signalled to other cells

4) Response to reverse the change

Question 9

What is Positive feedback?
(Simple Version)

Answer 9

1) Not common

2) Increases original change detected by receptors

3) Usually harmful

4) E.g. body temp falls, enzymes become less active, less heat released, temp continues to fall!

Being in labour is a good example of positive feedback - research this.