Topic 7

Question 1

What is homeostasis?

Answer 1

The maintenance of a stable internal environment in the body despite fluctuations in internal and external conditions.

Question 2

Why is homeostasis important?

Answer 2

To ensure optimum conditions for enzymes and cellular processes in the body.

Question 3

3 conditions within the body that must be controlled with homeostasis.

Answer 3

Temperature
Blood glucose concentration
Water levels

Question 4

Thermoregulation

Answer 4

The maintenance of core body temperature.

Question 5

Body temperature must be controlled…

Answer 5

Because enzymes work best at their optimum temperature. Deviations from this optimum temperature decrease the rate of enzyme-controlled reactions.

Question 6

Optimum temperature for the human body?

Answer 6

37 degrees

Question 7

The maintenance of an ideal body temperature depends on…

Answer 7

Negative feedback system:
Receptors
Hypothalamus
Effectors

Question 8

Where are temperature-sensitive receptors located?

Answer 8

Skin and hypothalamus

Question 9

What is the function of receptors in the skin and in the hypothalamus?

Answer 9

They detect changes in blood temperature and send information to the hypothalamus

Question 10

What is the function of the hypothalamus

Answer 10

It coordinates information from he receptors and sends instructions to the effectors

Question 11

What is the function of the effectors?

Answer 11

They produce a response to counteract the change in blood temperature and return it to the set point.

Question 12

What would the body do if there was an increase in temperature?

Answer 12

Vasodilation
Sweating
Hairs lie flat

Question 13

Which structure produces sweat?

Answer 13

Sweat glands found in the dermis

Question 14

How is sweat released from the skin?

Answer 14

Pores in the epidermis release sweat onto the skin’s surface which then evaporates

Question 15

How does sweating reduce ody temperature

Answer 15

Heat energy is used to evaporate sweat. Increased heat transfer from the skin to the environment decreases body temperature.

Question 16

What is vasodilation?

Answer 16

Dilation of blood vessels near the skins surface.
Blood flow loser to the skin surface.
Greater heat loss to the surroundings.

Question 17

What ones the body do if temperature drops?

Answer 17

Vasoconstriction
Shivering
Hair erector muscles contract

Question 18

How does shivering increase body temperature

Answer 18

Involuntary contraction of muscles generates heat energy from the respiration

Question 19

How does the contraction of hair erector muscles help to increase body temperature?

Answer 19

Hairs stand on end, creating pockets of air between hairs and a layer of insulation

Question 20

What is vasoconstriction

Answer 20

Constriction of blood vessels near the skin surface.
Less blood flow close to the skin.
Less heat lost to surroundings

Question 21

Which organ is responsible for the maintenance of blood glucose concentrations?

Answer 21

Pancreas

Question 22

How are blood glucose concentrations controlled?

Answer 22

Controlled by the hormone insulin and glucagon which are secreted by the pancreas

Question 23

Insulin and glucagon are antagonistic hormones. What does this mean?

Answer 23

They have opposite effects which contract each other.

Question 24

What is the role of insulin in controlling blood sugar?

Answer 24

Causes liver and muscle cells to increase their uptake of glucose from the blood.
Glucose is converted into glycogen, a storage molecule.

Question 25

What is the role of glucagon in the regulation of blood sugar levels?

Answer 25

Causes the breakdown of glycogen to glucose in the blood. Glucose is released into the blood.

Question 26

What is the control of blood glucose concentration an example of?

Answer 26

Negative feedback.

Question 27

What happens when blood glucose concentrations become to high?

Answer 27

Blood glucose increases above certain point. Pancreas secretes insulin and stops producing glucagon. Liver and muscle cells increase uptake of glucose. Glucose is converted to glycogen and stored. Some glucose may be stored as lipid in tissues. Blood glucose concentration decreases, returning to normal levels.

Question 28

Describe what happens when blood glucose concentrations become too high low.

Answer 28

Blood glucose concentration decreases below a set point. Pancreas secretes glucagon and stops producing insulin. Liver cells convert glycogen into glucose which is released into blood. Blood glucose concentration is lowered to normal level.