2) Responding To Change

Question 0

What is osmoregulation?

Answer 0

Regulating water content

Question 1

What is homeostasis?

Answer 1

Maintaining a stable internal environment

Question 2

What are some ways of gaining and losing water internally?

Answer 2

Gaining-
Drinking
Eating
Respiration

Losing-
Sweating
Breathing out water
Peeing

Question 3

What is thermoregulation?

Answer 3

Regulating body temperature

Question 4

Name the three types of homeostasis in a human.

Answer 4

Osmoregulation,
thermoregulation,
blood glucose regulation

Question 5

What is negative feedback?

Answer 5

1) A change in environment triggers a response that counteracts the changes
2) this means that the internal environment tends to stay at a constant, where the cells work best
3) this has limits so if the environment changes too much then it may not be able to counteract the changes and regulate the internal environment

Question 6

What is the hypothalamus?

Answer 6

A part of the brain that detects a change in the internal environment so causes a response in the dermis

Question 7

When you’re too hot, how to you thermoregulate?

Answer 7

• erector muscles relax so hairs lie flat
• lots of sweat is produced. When the sweat evaporates it transfers heat from your skin to the environment
• blood vessels close to the skin dilate (widen-vasodilation). This allows more blood to flow near the surface of the skin so it transfers more heat to surroundings

Question 8

When you’re too cold, how do you thermoregulate?

Answer 8

• erector muscles contract so hairs stand up which traps an insulating layer of air to keep you warm
• little sweat produced
• blood vessels near the surface of the skin constrict (vasoconstriction) so less blood flows near the surface meaning less heat is transferred to surroundings

Question 9

What are hormones?

Answer 9

Chemical messengers which travel in the blood to activate target cells

Question 10

Which is a faster information transmitter - hormones or nerves?

Answer 10

Nerves

Question 11

What is a target organ?

Answer 11

An organ that contains target cells which have he right receptors to respond to a hormone

Question 12

How fast do hormones travel?

Answer 12

At the speed of blood

Question 13

How lasting are the effects of hormones?

Answer 13

Long lasting

Question 14

What are neurones?

Answer 14

Nerve cells which transmit information as electrical impulses around the body

Question 15

What are dendrons?

Answer 15

Branched endings of neurones which enable them to connect with other neurones

Question 16

Where is the electrical impulse passed along?

Answer 16

The axon

Question 17

What does a myelin sheath do?

Answer 17

Acts as an electrical insulator which stops the impulse getting lost and speeds uo the impulse

Question 18

Why are neurones long?

Answer 18

It speeds up the impulse one long neurone is much quicker than lots of short ones joined together

Question 19

What is a synapse?

Answer 19

A tiny gap between two neurones

Question 20

How does an impulse travel alone a synapse?

Answer 20

1) The nerve impulse is transmitted by chemicals called neurotransmitters which diffuse across the gap
2) the neurotransmitters then set of a new electrical impulse in the next neurone

Question 21

What are the differences between hormones and nerves?

Answer 21

• nerves are fast messages, hormones are slower messages
• nerves act for a short time, hormones act for a long time
• nerves act on a very precise area, hormones act in a more general way
• nerves are an electrical message, hormones are a chemical message

Question 22

What is a stimulus?

Answer 22

A change in your environment that causes a reaction

Question 23

What are reflexes?

Answer 23

Automatic responses to certain stimuli

Question 24

Describe a reflex arc.

Answer 24

1) neurones in a reflex arc go through the spinal cord or an unconscious part of the brain to make the process quick and thoughtless
2) when a stimulus is detected by receptors impulse are sent along a sensory neurone to the central nervous system
3) in the cns the sensory neurone diffuses the impulse over a synapse to a relay neurone
4) relay neurones relay the impulses to a motor neurone (again diffuses across the synapse)
5) the impulses then travel along the motor neurone to the effector (muscle or gland)
6) the effector responds to the stimulus
7) quicker than normal responses because you don’t have time to think about the response