Homeostasis and Response

Question 1

What is homeostasis?

Answer 1

homeostasis is the
regulation of the internal conditions of a cell or organism to maintain
optimum conditions for function in response to internal and external
changes.

Question 2

Homeostasis maintains optimal conditions for enzyme action and all
cell functions. In the human body, What do these include control of?

Answer 2

• blood glucose concentration
• body temperature
• water levels.
  These automatic control systems may involve nervous responses or
  chemical responses.

Question 3

What do all control systems include?

Answer 3

• cells called receptors, which detect stimuli (changes in the
  environment)
• coordination centres (such as the brain, spinal cord and
  pancreas) that receive and process information from
  receptors
• effectors, muscles or glands, which bring about responses which restore optimum levels.

Question 4

What does the nervous system do?

Answer 4

The nervous system enables humans to react to their surroundings and to coordinate their behaviour.

Question 5

Explain how the nervous system works?

Answer 5

Information from receptors passes along cells (neurones) as electrical impulses to the central nervous system (CNS). The CNS is the brain and spinal cord. The CNS coordinates the response of
effectors which may be muscles contracting or glands secreting hormones

Question 6

What are reflex actions?

Answer 6

Reflex actions are automatic and rapid; they do not involve the conscious part of the brain

Question 7

Explain the structure and function of a sensory neurone?

Answer 7

At one end of the sensory neurone is the receptor cells where the nerve impulse begins. At the other end of the neurone are the axon terminals were the impulse is passed onto the CNS. Sensory neurones function to pass on information about the external or internal environment from receptors to the central nervous system.

Question 8

Explain the structure and function of a synapse relay neurone?

Question 9

Explain the structure and function of a motor neurone?

Question 10

What is the endocrine system?

Answer 10

The endocrine system is composed of glands which secrete chemicals called hormones directly into the bloodstream. The blood
carries the hormone to a target organ where it produces an effect.
Compared to the nervous system the effects are slower but act for longer

Question 11

What is the pituitary gland and what does it do?

Answer 11

The pituitary gland in the brain is a ‘master gland’ which secretes several hormones into the blood in response to body conditions.
These hormones in turn act on other glands to stimulate other hormones to be released to bring about effects.

Question 12

How is blood glucose concentration controlled?

Answer 12

Blood glucose concentration is monitored and controlled by the pancreas.

Question 13

What happens when the blood glucose concentration is too high?

Answer 13

If the blood glucose concentration is too high, the pancreas produces the hormone insulin that causes glucose to move from the
blood into the cells. In liver and muscle cells excess glucose is converted to glycogen for storage.

Question 14

How does insulin control blood glucose levels?

Question 15

What is Type 1 diabetes and how is it treated?

Answer 15

Type 1 diabetes is a disorder in which the pancreas fails to produce sufficient insulin. It is characterised by uncontrolled high blood
glucose levels and is normally treated with insulin injections.

Question 16

What is type 2 diabetes and how is it treated?

Answer 16

In Type 2 diabetes the body cells no longer respond to insulin produced by the pancreas. A carbohydrate controlled diet and an
exercise regime are common treatments. Obesity is a risk factor for Type 2 diabetes

Question 17

What happens if blood glucose concentration is too low?

Answer 17

If the blood glucose concentration is too low, the pancreas produces the hormone glucagon that causes glycogen to be
converted into glucose and released into the blood.

Question 18

how does glucagon interacts with insulin in a negative feedback cycle to control blood glucose (sugar) levels in the body.

Question 19

Where is Oestrogen produced and what does it do?

Answer 19

Oestrogen is the main female reproductive hormone produced in the ovary. At puberty eggs begin to mature and one is released
approximately every 28 days. This is called ovulation.

Question 20

Where is testosterone produced and what does it do?

Answer 20

Testosterone is the main male reproductive hormone produced by the testes and it stimulates sperm production.

Question 21

What does FSH do?

Answer 21

Follicle stimulating hormone (FSH) causes maturation of an egg in the ovary.

Question 22

What does LH do?

Answer 22

Luteinising hormone (LH) stimulates the release of the egg

Question 23

What do both Oestrogen and Progesterone do in the menstrual cycle?

Answer 23

Oestrogen and progesterone are involved in maintaining the uterus lining.

Question 24

What do oral contraceptives contain?

Answer 24

oral contraceptives that contain hormones to inhibit FSH production so that no eggs mature

Question 25

What does the injection, implant and skin patch do?

Answer 25

injection, implant or skin patch of slow release progesterone
to inhibit the maturation and release of eggs for a number of months or years

Question 26

What is in a fertility drug for women?

Answer 26

FSH and LH

Question 27

What are the stages of IVF?

Answer 27

• IVF involves giving a mother FSH and LH to stimulate the
  maturation of several eggs.
• The eggs are collected from the mother and fertilised by
  sperm from the father in the laboratory.
• The fertilised eggs develop into embryos.
• At the stage when they are tiny balls of cells, one or two
  embryos are inserted into the mother’s uterus (womb).

Question 28

What are problems with fertility treatment for women?

Answer 28

• it is very emotionally and physically stressful
• the success rates are not high
• it can lead to multiple births which are a risk to both the
  babies and the mother.

Question 29

What does adrenaline do in the body?

Answer 29

Adrenaline is produced by the adrenal glands in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’.

Question 30

What does thyroxine do in the body?

Answer 30

Thyroxine from the thyroid gland stimulates the basal metabolicrate. It plays an important role in growth and development.