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BIOLOGY IGCSE > HOMEOSTASIS > Flashcards

HOMEOSTASIS Flashcards

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1
Q

What is homeostasis?

A

Maintenance of a constant internal environment and is the control of internal conditions within set limits achieved by negative feedback

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2
Q

Give examples of internal conditions

A

Temperature
blood pressure
water concentration
glucose concentration

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3
Q

When does negative feedback happen?

A

When conditions change from the ideal point and returns conditions to this set point

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4
Q

What are negative feedback mechanisms usually?

A

A continuous cycle of bringing levels down and then bringing them back up so that overall they stay withing a narrow range of what is considered normal

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5
Q

What is the ideal body temperature for enzymes?

A

37 C

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6
Q

What is hyperthermia?

A

When heat gain exceeds heat loss and the temperature rises

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7
Q

What is hypothermia?

A

When heat loss exceeds heat gain and the temperature falls.

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8
Q

Where is regulation controlled?

A

In the hypothalamus which contains receptors sensitive to the temperature of the blood.

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9
Q

Where are there temperature receptors?

A

The skin and sends impulses via sensory neurones

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10
Q

What is the top layer of the skin called?

A

Epidermis

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11
Q

What is the lower layer of the skin called?

A

Dermis

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12
Q

What is the dermis made of?

A

Connective tissue

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13
Q

What does the connective tissue contain?

A

Elastic fibres and collagen fibres

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14
Q

What happens as a person gets older?

A

Fibers lose their elasticity so the skin becomes loose and wrinkled

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15
Q

What does the dermis contain?

A

Sweat glands

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16
Q

What do the sweat glands do?

A

They secrete a liquid called sweat which is mostly water with small amounts of salts and urea dissolved in it

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17
Q

How does sweat travel?

A

It travels up the sweat ducts and onto the surface of the skin through the sweat pores

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18
Q

What happens when it is too warm?

A

Hair erector muscle relaxes lowering the hair
a thin insulating layer of air is trapped above the skin
more heat is lost to the environment by evaporation convection and radiation

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19
Q

What happens when it is too cold?

A

The hair erector muscle contracts raising the hair
the hairs trap a thicker layer of air above the skin
The air insulates the skin

20
Q

What is underneath the dermis?

A

A layer of fat called adipose tissue

21
Q

What does the adipose tissue do?

A

Helps insulate the body against heat loss and acts as an energy reserve

22
Q

What is shivering?

A

When muscles in some parts of the body contract and relax very quickly

23
Q

How does shivering help?

A

Heat is generated in the muscles and warms the blood as it flows through them

24
Q

What does the dermis contain?

A

Blood vessels and nerve endings

25
Q

What do the nerve endings do?

A

They are sensitive to touch, pain, pressure and temperature

26
Q

What happens to our arterioles when we are cold?

A

They become narrower

27
Q

What is it called when our arterioles contract?

A

Vasoconstriction

28
Q

How does Vasoconstriction help?

A

Reduces the amount of heat loss from blood by radiation as less blood flows through the surface of the skin

29
Q

What happens when our arterioles when we are hot?

A

They dilate

30
Q

What is it called when our arterioles dilate?

A

Vasodilation

31
Q

How does Vasodilation help?

A

there is more blood and bc there is a lot of blood near the surface of the skin heat is readily lost from the blood into the air by radiation.

32
Q

What is an effector?

A

An effector is a part of the body that creates a response such as muscles

33
Q

What happens when the body temperature raises?

A

Temperature receptors in the skin detect an increase
Nervous impulse sent to the hypothalamus and it coordinates a response
sweat is released and blood vessels dilate

34
Q

What is produced when blood glucose rises?

A

Insulin

35
Q

What happens when blood glucose rises?

A

Insulin produced
stimulates the liver
muscle cells to convert excess glucose into glycogen

36
Q

How are blood glucose levels controlled?

A

Negative feedback mechanism involving glucagon and insulin

37
Q

Where are insulin and glucagon produced?

A

Pancreas

38
Q

Why do cells need glucose?

A

To respire to release energy

39
Q

Why is too much glucose not good for cells?

A

water moves out of the cells and into the blood by osmosis

40
Q

What is type 1 diabetes?

A

A condition where the blood glucose levels are not able to be regulated as the insulin secreting cells in the pancreas are not able to produce insulin

41
Q

What happens if you have Type 1 diabetes?

A

the blood glucose levels are too high

42
Q

How can you treat type 1 diabetes?

A

Injecting insulin

43
Q

What can having high or low blood glucose concentrations cause?

A

Damage to numerous body organs

44
Q

What is hyperglycaemia?

A

When the blood glucose concentration goes up and stays up

45
Q

What is hypoglycaemia?

A

When the blood glucose drops very low

46
Q

What can hypoglycaemia cause a person to feel?

A

very tires
confusion
irrational behaviour

47
Q

How can people monitor type 1 diabetes?

A

Levels of physical activity

their diet affects the amount of insulin needed

BIOLOGY IGCSE (16 decks)

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