Homeostasis

Question 1

Definition of homeostasis

Answer 1

Various processes keeping the internal environment constant by controlling levels of

1) WATER
2) IONS
3) pH
4) GLUCOSE
5) TEMPERATURE
6) OXYGEN + CARBON DIOXIDE CONCENTRATIONS
7) ENZYMES
8) HORMONES

Question 2

Explain homeostasis

Answer 2

Result of coordination of your nervous system, hormones and body organs.

Question 3

What is negative feedback?

Answer 3

A concept of control that occurs when the body seeks to maintain an optimal set-point and if the internal conditions deviate from this, the body reacts and brings it back towards the set point.

Question 4

Describe control of glucose concentrations by liver

Answer 4

INSULIN stimulates the liver to take up
glucose from the blood ——-> to glycogen

Because too much glucose would affect the OSMOTIC BALANCE and cause water to move out of cells. However our cells constantly respire and need a steady supply of glucose.

Question 5

Describe role of insulin and glucagon from the pancreas

Answer 5

A rise of glucose is detected by the pancreas and as a result it produces INSULIN.
When a drop of glucose is sensed, the pancreas produces GLUCAGON.

Question 6

What does insulin do?

Answer 6

Glucose –> glycogen

Question 7

What does glucagon do?

Answer 7

Glycogen —-> glucose

Question 8

Symptoms of type 1 diabete

Answer 8

Being Thirsty
Feeling hungry
Feeling tired all the time
Blurry eyesight
Losing weight
Urinating more often
Stomach pain
Rapid breathing
Dry skin and mouth
Nausea and vomiting

Question 9

Treatments of type 1 diabete

Answer 9

INSULIN

HEALTHY DIET

EXERCISE

Question 10

Explain the role of insulin in type 1 diabete

Answer 10

Insulin is a hormone , released by pancreas that converts
Soluble glucose —-> insoluble glycogen

Makes glucose levels drop

Question 11

Explain role of healthy diet in Type 1 diabete

Answer 11

Avoid sugary drinks as they put glucose levels up high + quickly
Dont eat food with large amounts of calories and fat
Include carbohydrates to meal otherwise insulin may cause glucose levels to drop too low

Question 12

Explain role of exercise in Type 1 diabete

Answer 12

Regular excercise helps control the amount of sugar in the blood. It increases the insulin sensitivity so after exercise, your body doesn’t need as much insulin to process carbohydrates.

• lower blood pressure
• Better control of weight
• more energy

Question 13

Draw diagram of skin

Answer 13

—see book

Question 14

Describe maintenance of a constant internal body temperature by insulation

Answer 14

INSULATION - by skin that enables them to conserve heat by having SUBCUTANEOUS FAT beneath the skin. This is because it does not conduct heat very well. Mammals have fur or air, which traps a layer of air close to the skin. Air is a poor conductor of heat so air pockets in the fur reduce loss of heat by keeping convection current of air away from the warm surface of skin.

Question 15

Describe maintenance of a constant internal body temperature (x4)

Answer 15

Insulation
Sweating
Shivering
Brain

Question 16

Describe maintenance of a constant internal body temperature by brain

Answer 16

The HYPOTHALAMUS in the THERMOREGULATORY CENTER of the brain monitors the temperature of the blood that passes through it and takes action if temp. Starts to deviate from the set point, it takes actions. It sends impulses to the arterioles (skin) causing them dilate and let more blood flow nearer the skin. —-> this is because thermal energy from blood is lost through radiation of heat from the skin and convection helps carry away this heat)
= vasodilation

Question 17

Describe maintenance of a constant internal body temperature by sweat glands

Answer 17

Sweat glands release sweat through sweat pores in the skin. This thin film of sweat consists of mostly water. When the water evaporates, it takes away thermal energy from the skin, cooling it down.

—-> lose heat

Question 18

Describe maintenance of a constant internal body temperature by rhythmic muscles

Answer 18

Rhythmic muscles’ contraction causes shivering , with the increased respiration release HEAT so temperature will increase.

Question 19

What is vasodilation ?

Answer 19

Vasodilation happens when the body’s temperature is ABOVE 37 degrees celsius.
Arterioles dilate so get wider which sends more blood to the skin surface capillaries to maintain an internal body temperature of 37 degrees. This is because thermal energy from blood is lost through radiation of heat from the skin and convection helps carry away heat.

Question 20

What is vasoconstriction?

Answer 20

Vasoconstriction happens when body temperature is below 37 degrees.
Arterioles constrict to go narrower so less blood goes to the surface to keep body warm.

Question 21

Define the term gravitropism

Answer 21

A response in which parts of a plant grow towards or away from gravity.

Question 22

Define the phototropism

Answer 22

A response in which parts of a plant grow towards or away from the direction from which light is coming.

Question 23

What is auxin?

Answer 23

A plant hormone that controls direction of growth. Auxin always moves to the shaded side of the plant (away from light) so that the plant bends towards the light to get more light for photosynthesis.

Question 24

Describe the use in weedkillers of the synthetic plant hormone 2,4-D

Answer 24

2,4-D is a synthetic plant hormone used in weedkillers that affects BROAD-LEAVES PLANTS (usually weeds) because it affects the rate of cell division so it occurs too quickly for the plant to maintain.