B5 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

How is homeostasis used in the human body?

Answer 2

In the human body homeostasis is used to keep the blood glucose concentration, body temperature and water levels constant.

Question 3

What is negative feedback?

Answer 3

Negative feedback is a mechanism used when the automatic control system keeps the body’s internal environment stable.

When something get’s to high or to low e.g blood glucose levels, the body uses negative feedback to bring it back to normal.

Question 4

What is the central nervouse system? (CNS)

Answer 4

The CNS is a coordination centre. It receives information from the receptors and then coordinates a response. The response is carried out by effectors.

Question 5

What is a stimulus?

Answer 5

A change in the environment e.g hearing a loud bang.

Question 6

What are receptors?

Answer 6

Receptors are cells that detect stimuli. E.g sound receptors in the ears.

Question 7

What are effectors?

Answer 7

Effectors respond to nervous impulses and bring about change. Muscles and glands are known as effectors. E.g muscle contracts.

Question 8

What is a sensory neuron?

Answer 8

The neurons that carry electical impulses from the receptor to the CNS.

Question 9

What is a motor neuron?

Answer 9

The neurons that carry electrical impulses from the CNS to the effectors.

Question 10

Describe how a neuron is adapted for it’s function.

Answer 10

• Thin projections called dendrites extend from the cell body and connect with other neurones, allowing electrical impulses to pass from one to the other.

• The axons of most neurones are insulated by a layer called the myelin sheath.
This ensure the impulses travel rapidly along the axon.

Question 11

Describe the pathway of an electrical impulse during a conscious action e.g. putting up your hand to answer a question.

Answer 11

Stimulus -> Receptor - Sensory neuron -> CNS (brain) - Motor neuron -> Effector (muscle/gland) -> response.

Question 12

What is a synapse?

Answer 12

A synapse is a gap between two neurons. Electrical impulses can not cross the synapse.

They are stored In vesicles in the pre-synaptic neuron.

Question 13

Describe how electrical impulses can cross the synapse.

Answer 13

1) Electrical impulse reaches the end of the first neuron.
2) This stimulates the release of neurotransmitter chemicals.
3) The neurotransmitter chemicals diffuse across the synapse.
4) They bind to receptors on the next neuron.
5) This binding of the neurotransmitters to the receptors stimulates the second neuron to transmit an electrical impulse (same message) along its axon.

Question 14

What is a reflex?

Answer 14

Reflexes are rapid, automatic responses to certain stimuli that don’t involve the conscious part of the brain. They can reduce the chances of being injured.

Question 15

Describe the pathway of an electrical impulse during a reflex action.

Answer 15

Stimulus - Receptor - Sensory neuron -> CNS (spinal cord) -> Motor neuron -> Effector (muscle/gland) -> response.

Question 16

What is a reflex action?

Answer 16

A reflex action is an automatic (involuntary) and rapid response to a stimulus.

Question 17

What are hormones?

Answer 17

. Hormones are chemical molecules released directly into the blood.

. They are carried in the blood to other parts of the body, but only effect particular cells in particular organs (called tagret organs).

. Hormones control things in organs and cells that need constant adjustment.

Question 18

What is a gland?

Answer 18

Any organ that releases hormones. E.g pituitary gland, thyroid, adrenal gland.

Question 19

What is the pituitary gland?

Answer 19

The pituitary gland produces many hormones that regulate body conditions.
Known as the ‘master gland’ as the hormones produced act on other glands, directing them to release hormones that bring about change.

Question 20

What is the thyroid gland?

Answer 20

This gland Produces thyroxine, which is involved in regulating things like rate of metabolism, heart rate and temperature.

Question 21

What is the Adrenal Gland?

Answer 21

Produces adrenaline, used to prepare body for ‘fight or flight response.’

Question 22

What is the pancreas?

Answer 22

Produces insulin, used to regulate blood glucose levels.

Question 23

What are ovaries and testes?

Answer 23

Ovaries - only in females, produce oestrogen which is involved in the menstrual cycle.

Testes - only in males, controls puberty and sperm production.

Question 24

What are the differences between nerves and hormones?

Answer 24

Nerves: very fast action, act for a very short time, act on a very precise area.

Hormones: slower action, acts for a long time, acts in a more general way.

Question 25

Explain how the hormone glucagon causes blood glucose levels to rise.

Answer 25

Glucagon travels in the bloodstream to the liver (where there is a store of glucose).
The liver converts stored glycogen back into glucose.
Blood glucose levels therefore rise.

Question 26

What is type 1 diabetes?

Answer 26

Type 1 diabetes is where the pancreas produces little or no insulin. Meaning a person’s blood glucose levels can rise to a level that can kill them.

Question 27

What is the treatment for type 1 diabetes?

Answer 27

People with type 1 diabetes need insulin therapy. This involves several injections of insulin throughout the day, so that glucose is removed from the blood quickly once the food has been digested. Stopping the level getting to high.

Question 28

How might a Doctor become aware that a patient has type 1 diabetes?

Answer 28

It is characterised by uncontrolled high blood glucose levels.
The patient may have glucose in their urine.

Question 29

What is type 2 diabetes?

Answer 29

Type 2 diabetes is where a person becomes resistant to their own insulin. (They still produce insulin but there body’s cells don’t respond properly to the hormone.)

Question 30

What are some risk factors for type 2 diabetes.

Answer 30

Lack of exercise
Obesity
Family history
Diet high in saturated fat

Question 31

Name 3 symptoms of both type 1 and type 2 diabetes.

Answer 31

Frequent urination
Being really thirsty
Blurred vision

Question 32

What is the reproductive hormone in men?

Answer 32

The reproductive hormone is testosterone. It is produced by the testes and stimulates sperm production.

Question 33

What is the reproductive hormone in women?

Answer 33

In women the reproductive hormone is oestrogen. It is produced in the Ovaries and is also involved in the menstual cycle.

Question 34

What is contraception?

Answer 34

Contraception tries to stip the sperm from reaching the ovulated egg. Preventing pregnancy.

Question 35

What are some methods of contraception?

Answer 35

Condom
Contraception pill
Contraceptive injection
Contraceptive patch

Question 36

What is Adrenaline?

Answer 36

Adrenaline is a hormone released by the adrenal glands, just above the kidneys. Adrenaline is released in response to stressful or scary situations. The brain detects fear or stress and sends nervous impulses to the adrenal glands, which respond by secretting adrenaline.

Question 37

What does Adrenaline prepare you for?

Answer 37

It prepares you for “fight or flight” by triggering mechanisms that increase the supply of Oxegyn and glucose to cells in the brain and muscles. E.g adrenaline increases heart rate.

Question 38

What is thyroxine?

Answer 38

Thyroxine is a hormone released by the thyroid gland in the neck. It regulates metabolic rate. Also important for stimulating protien synthesis for growth and development.