B1f - staying in balance

Question 1

What is homeostasis(5)

Answer 1

Maintaining a constant internal environment by balancing inputs and outputs

Temperature, water and carbon dioxide levels are kept steady so cells can work at their optimum level

Works through negative feedback

• Changes in the environment trigger a response that counteracts the changes - e.g. a rise in body temp causes a response that lowers body temp
• This only works within certain limits - if the environment changes too much then it might not be possible to counteract it

Question 2

What is the optimum body temperature and why(2)

Answer 2

37°C

Because enzymes in the human body have an optimum temp that is around 37°C

Question 3

What can high temperature cause(3)

Answer 3

Heat stroke

Dehydration

Death

Question 4

How is body temperature kept constant(2)

Answer 4

Blood temperature is monitored by the hypothalamus gland in the brain

Brain will bring about temperature control mechanisms(e.g. vasoconstriction or vasodilation) via the nervous and hormonal systems

Question 5

How does the body lower body temperature(6)

Answer 5

Hairs lie flat

Lots of sweat is produced
-when sweat evaporates it uses heat from the skin. Transfers heat from skin to environment

Vasodilation

• blood vessels close to the surface of the skin widen.
• allows more blood to flow near the surface, so they can radiate more heat into surroundings

Question 6

How does the body increase body temperature(6)

Answer 6

Hairs stand on end to trap an insulating layer of air which helps keep you warm

Very little sweat is produced

You shiver, and the movement generates heat in the muscles

Vasoconstriction

• blood vessels near the surface narrows
• less blood flow near the surface so less heat radiated into surroundings

Question 7

What can low temperature cause(2)

Answer 7

Hypothermia

Death

Question 8

What does insulin do(4)

Answer 8

Insulin converts excess glucose in the blood into glycogen, which is stored in the liver, this regulates blood sugar level

• if the blood glucose level is too high it may kill the person
• when blood glucose level is too high, insulin is added
• when blood glucose level is too low, insulin is not added

Question 9

Describe type 1 diabetes(4)

Answer 9

Caused by the pancreas produces little or no insulin

Must be treated by injecting insulin into the blood

• amount of insulin needed depends on diet and how active they are
• intense exercise needs more glucose to be present in the blood, so a lower insulin dose is required

Question 10

Describe type 2 diabetes(2)

Answer 10

Where a person becomes resistant to insulin (their body’s cells don’t respond properly to the hormone)

Usually controlled by limiting the intake of foods rich in simple carbohydrates(e.g. sugars)

Question 11

Explain why responses controlled by hormones are usually slower than responses controlled by the nervous system

Answer 11

Hormones travel in the blood, so it can take quite a while for them to get to their target organ