Homeostasis and Response

Question 1

Central Nervous System

Answer 1

The part of the nervous system made up of the brain and the spinal cord.

Question 2

What are neurones?

Answer 2

Specialised cells that carry electrical impulses.

Question 3

What are the five parts of control systems in the nervous system?

Answer 3

1. Stimulus - environmental change
2. Receptors - detect the change
3. Coordinator - organises the response
4. Effectors - create a response
5. Response - caused by an effector

Question 4

Synapse

Answer 4

A gap between two neurons.

Question 5

Describe the parts of a reflex arc.

Answer 5

• Stimulus
• Receptor
• Sensory neurone - impulses travel along these to the spinal cord
• Relay neurone - located within the spinal cord, and connects sensory and motor neurones
• Motor neurone - connects the relay neurone to the effector
• Effector
• Response

Question 6

What is a reflex arc?

Answer 6

The pathway of information from a sensory neuron through an inter neuron to a motor neuron.

Question 7

Hormones

Answer 7

Chemicals produced by glands in the body

Question 8

Describe the characteristics of a nerve response.

Answer 8

Fast, short lived, electrical response transmitted through neurones

Question 9

Gland

Answer 9

An organ or tissue that makes a substance for release

Question 10

What happens if blood glucose is too high?

Answer 10

Insulin is released, causing glucose to move from the blood into the liver cells.

Question 11

What is Type 1 diabetes and how can it be controlled and monitored?

Answer 11

It occurs when the pancreas doesn’t produce enough insulin, meaning the body cells can’t take up glucose.
It can be controlled by monitoring the diet and injecting appropriate amounts of insulin. Exercise is also important as it uses glucose to create energy through respiration.

Question 12

What is diabetes?

Answer 12

A disease in which the body is unable to regulate blood sugar.

Question 13

What is type 2 diabetes and how is it controlled?

Answer 13

It is when the person’s body cells no longer respond to insulin produced by the pancreas.
It can be controlled by a low carbohydrate diet (carbohydrate is digested into glucose which raises the overall blood glucose level) and exercise.

Question 14

Puberty definition and secondary sexual characteristics.

Answer 14

Changes that occur due to reproductive organs.
Boys - testosterone is released by the testes and stimulates sperm production
Girls - oestrogen is released by the ovaries and causes eggs to be released

Question 15

Negative feedback

Answer 15

A mechanism where changes to conditions cause an action to reverse the change, keeping conditions stable.

Question 16

Pituitary gland

Answer 16

An endocrine gland that is located just below the centre of the brain and releases a number of important hormones

Question 17

Describe thyroxine.

Answer 17

Hormone produced by the thyroid gland which stimulates the basal metabolic rate.

Question 18

Describe adrenaline.

Answer 18

Produced by the adrenal glands at times of fear or stress and creates a ‘flight or fight’ response.

Question 19

Explain how negative feedback works in blood glucose control.

Answer 19

If the blood glucose levels are too high, insulin is secreted by the pancreas
Liver converts glucose to glycogen for storage and the blood glucose decreases
If the blood glucose is too low glucagon is secreted from the pancreas instead of insulin
The liver converts glycogen back to glucose and the blood glucose increases

Question 20

Glucagon

Answer 20

A hormone produced by the pancreas that promotes the breakdown of glycogen into glucose in the liver

Question 21

Glycogen

Answer 21

Animals store glucose as glycogen in their liver and muscle tissues

Question 22

Which hormones are controlled by negative feedback?

Answer 22

Thyroxine and ADH

Question 23

Why is glucose important in blood sugar regulation?

Answer 23

Excess glucose is stored in the liver.

Question 24

Oestrogen

Answer 24

A female sex hormone produced in the ovaries, which is responsible for puberty in girls and the regulation of the menstrual cycle

Question 25

Describe how different hormones affect the menstrual cycle.

Answer 25

- FSH causes eggs to mature in the ovary - Oestrogen repairs and thickens the uterus lining - LH triggers ovulation of the matured egg - Progesterone maintains the lining of the uterus during the middle part of the menstrual cycle and during pregnancy

Question 26

Menstrual cycle

Answer 26

Recurring series of events in the human female reproductive system

Question 27

What is Follicle Stimulating Hormone?

Answer 27

It stimulates oestrogen production and the growth of follicles in the ovary. It is secreted by the pituitary gland.

Question 28

What is Luteinising Hormone?

Answer 28

It is secreted by the pituitary gland and stimulates ovulation.

Question 29

What are examples of hormonal methods of contraception?

Answer 29

- **Oral contraceptive** uses oestrogen or progesterone to prevent FSH being released so eggs can’t mature - **Injections, implants or patches** release progesterone which inhibit maturation and release of eggs for many months or years

Question 30

What are examples of non-hormonal contraceptives?

Answer 30

**Intrauterine devices (IUDs)** prevent the implantation of an embryo **Spermicidal agents** kill sperm **Abstaining** from sexual intercourse Surgical methods such as **sterilisation**, which is irreversible

Question 31

What are examples of fertility drugs and what are the risks of using them?

Answer 31

**LH and FSH** which stimulate eggs to mature in the ovaries. RISK: Undergoing fertility treatments may result in multiple pregnancies, which can lead to medical and health complications.

Question 32

What is IVF and the process of it?

Answer 32

It is used to help infertile couples have a baby. Eggs are collected from the mother and fertilised by the father’s sperm in a laboratory. Fertilised eggs develop into embryos. One or two embryos are implanted into the woman’s uterus, to increase the chance of a successful pregnancy. There is also an increased chance of twins.

Question 33

What are the advantages of infertility treatments?

Answer 33

Safe - been used since 1978 Helps infertile couples Screening for genetic diseases can be included

Question 34

What are the disadvantages of infertility treatments?

Answer 34

Emotionally and physically stressful Multiple birth complaints Low success rates Ethical concerns

Question 35

How how have recent scientific developments in technology helped IVF treatments?

Answer 35

Microscope developments have allowed more accurate techniques.

Question 36

Why can’t everyone have IVF on the NHS?

Answer 36

There are many guidelines to see who can qualify for the treatment and it is a very expensive procedure.

Question 37

What are two examples of effectors?

Answer 37

Glands and muscles.

Question 38

Why do reflex arc signals not go immediately to the brain?

Answer 38

Because it would take longer to react if they did.

Question 39

Describe the structure and function of the nerves in the nervous system.

Answer 39

- The central nervous system is made from the brain and spinal cord - The peripheral nervous system is a network of nerves that cover the rest of the body - Receptor cells in sense organs start electrical signals which travel along sensory neurones to the central nervous system - Relay neurones carry electrical signals around the central nervous system - Motor neurones carry electrical signals away from the central nervous system to effectors which are muscles or glands - Gaps between neurones are called synapses - All neurones have extended projects called axons along which electrical signals travel - Axons are insulated by myelin sheaths to speed up the electrical signals

Question 40

Describe what happens at a synapse.

Answer 40

- Where two neurones meet there is a small gap, a synapse. - An electrical impulse travels along the first axon. - This triggers the nerve-ending of a neurone to release chemical messengers called neurotransmitters into the synapse. - These chemicals diffuse across the synapse (the gap) and bind with receptor molecules on the membrane of the second neurone. - The receptor molecules on the second neurone bind only to the specific neurotransmitters released from the first neurone. - This stimulates the second neurone to transmit the electrical impulse.

Question 41

Similarities and differences between the role of hormones in the endocrine system and nerves in the nervous system.

Answer 41

Both hormones and electrical impulses in nerves send signals. —————————————————— Electrical signals in nerves move quickly. Hormones are released by glands. Hormones move in the blood. Hormones act upon a target organ. Hormones control the menstrual cycle, homeostasis and puberty (three marks). Electrical signals in nerves allow us to see, hear, feel, smell and taste.

Question 42

How are nerve cells adapted for their function?

Answer 42

They have a long axon which carries the electrical signal. The axon is insulated by the myelin sheath. Nerve cells have tiny branches called dendrones. These branch further into dendrites. Dendrites receive signals from other nerve cells.