Homeostasis CH14

Question 1

Define Homeostasis

Answer 1

Homeostasis is the maintenance of a constant internal environment

Question 2

Describe what Endothermic means

Answer 2

Can keep their temperatures constant even though the temperature of the environment is changing

Question 3

Describe what Ectothermic means

Answer 3

Animals who don’t keep their temperatures constant when the temperature of the environment changes

Question 4

What is the hypothalamus

Answer 4

The part of the brain which is at the centre of the control mechanism that keeps internal temperature constant. It controls the temperature of the blood

Question 5

What happens when the body is too cold?

Answer 5

1. The erector muscles contract which pulls hairs upon end
2. The upright hairs trap a warm layer of air next to the skin which insulates it
3. Arterioles in the skin constrict, so not much blood flows through them
4. Capillaries are supplied with less blood from arterioles, so remain narrow

Question 6

What happens when the body is too hot?

Answer 6

1. Sweat evapourates from the skin surface, cooling it
2. Erector muscles relax, so the hairs lie flat and do not trap warm air
3. More blood is brought to the surface capillaries where it can lose heat

Question 7

What is vasoconstriction?

Answer 7

The arterioles that supply the blood capillaries near the surface of the skin become narrower, allowing less blood to be near the skin which prevents heat loss

Question 8

What is vasodilation?

Answer 8

When the arterioles supplying the capillaries near the surface of the skin get wider, bringing more blood to the surface which encourages heat loss

Question 9

What is negative feedback?

Answer 9

Negative Feedback is a mechanism used in homeostasis in which a change in a parameter brings about action that push it back towards normal

Question 10

Why do cells need glucose?

Answer 10

Cells need a good supply of glucose so they can respire and release energy

Question 11

What is the effect of having too much glucose in the blood?

Answer 11

Too much glucose in the blood can cause water to move out of the cells and into the blood via osmosis

Question 12

Which organs control the blood glucose concentration?

Answer 12

The pancreas and the liver

Question 13

which two hormones are involved in controlling the blood glucose concentration levels?

Answer 13

Insulin and glucagon

Question 14

How are these hormones secreted from the pancreas?

Answer 14

Scattered through the pancreas are groups of cells called Islets of Langerhans. These cells make Insulin and glucagon

Question 15

What does Insulin and Glucagon do ?

Answer 15

Insulin LOWERS blood glucose

Glucagon INCREASES blood glucose

Question 16

What are these 2 hormones affect on the liver?

Answer 16

When insulin reaches the liver, it causes the liver to absorb glucose from the blood. Glucagon causes the liver to break glycogen into glucose

Question 17

What is type one diabeties ?

Answer 17

Death of the cells, Islets of Langerhans, that secrete insulin

Question 18

What is hyperglycaemia?

Answer 18

When the blood glucose concentration goes up and stays up . They will have dried mouths, blurred vision and feel thirsty

Question 19

What is Hypoglycaemia?

Answer 19

When the blood glucose concentration goes down and stays down. Because no insulin as been released, no glycogen stores build up and no glucose is released