Topic 5 - Homeostasis and response (1)

Question 1

What is homeostasis?

Answer 1

The process of maintaining a stable internal environment (regulating the conditions inside of you body + cells)
- in response to changes in both internal and external conditions

Question 2

Why must conditions in your body be kept steady even when the external environment changes?

Answer 2

maintains optimum conditions for enzyme action and all cell functions

Question 3

What is the definition of homeostasis?

Answer 3

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 4

What three factors does homeostasis maintain?

Answer 4

• blood glucose concentration
• body temperature
• water levels

Question 5

What regulates your constant internal environment?
What are two types of these?

Answer 5

• automatic control systems
• nervous responses /communication or chemical (hormonal) responses/ communication

Question 6

What are the three main components of your automatic control systems?

Answer 6

• receptors
• coordination centres (including the brain, spinal cord and pancreas)
• effectors

Question 7

What are receptors?

Answer 7

cells which detects stimuli (changes in the environment)

Question 8

What are coordination centres?

Answer 8

• such as the brain, spinal cord and pancreas
• they recieve and process information from the receptors

Question 9

What are effectors?

Answer 9

muscles or lands which bring about responses which restore optimum levels

Question 10

What is the name of the mechanism used by your automatic control systems to keep your internal environment stable?

Answer 10

negative feedback

Question 11

What is a stimulus?

Answer 11

A change in the environment

Question 12

Explain when your body uses negative feedback?

Answer 12

When the level of something (e.g. water or temperature) gets too high or low
your body uses negative feedback to bring it back to normal
- this process is automatic (it happens without you even thinking about it)

Question 13

What does a nervous system enable humans to do?

Answer 13

react to their surroundings and coordinate their behaviour

Question 14

What are the 4 main parts of the human nervous system?

Answer 14

• central nervous system (CNS)
• sensory neurones
• motor neurones
• effectors

Question 15

What is the central nervous system?

Answer 15

• In vertibrates this consists of the brain and spinal cord only
• In mammals, the CNS is connected to the body by sensory and motor neurones

Question 16

What is the function of the central nervous system (CNS)?

Answer 16

The CNS is a coordination centre
recieves information from receptors and coordinates a response carried out by the effectors
these may be muscles contracting or glands secreting hormones

Question 17

What are sensory neurones?

Answer 17

the neurones that carry information as electrical impulses from receptors to the CNS

Question 18

What are motor neurones?

Answer 18

neurones that carry electrcal impulses from the CNS to the effectors

Question 19

What are effectors?

Answer 19

All you muscles and glands, which respons to nervous impulses

Question 20

What are receptors?

Answer 20

cells that detect stimuli
- there are many diiferent types of receptors (taste receptors on the tongueand sound receptors in the ears)

Question 21

REMEMBER:
Receptors and Effectors can form part of complex organs

Question 22

Give an example of a receptor forming part of a larger, complex organ?

Answer 22

the retina of the eye is covered in light receptor cells

Question 23

What it the function of effectors?

Answer 23

they respond to nervous impulses and bring about a change

Question 24

What are muscles and glands examples of and how do they each respond to nervous impulses?

Answer 24

• muscles and glands are known as effectors
• muscles contract
• gmands secrete hormones

Question 25

What is a synapse?

Answer 25

the connection between two neurones

Question 26

What is the connection between two neurones called?

Answer 26

a synapse

Question 27

How do synapses connect neurones?

Answer 27

- the nerve signal is transferred by chemicals which diffuse across the gap - these chemicals then set off a new electrical signal in the next neurone

Question 28

What are reflexes and how are they useful to humans?

Answer 28

- they are rapid, automatic responses to certain stimuli that don't involve a concious part of the brain - they can reduce the chances of being injured

Question 29

REFLEXES HELP TO PREVENT INJURY: Explain what reflex action would take place if someone shines a bright light in your eyes?

Answer 29

your pupils automatically get smaller so that less light gets into the eye this stops them getting damaged

Question 30

REFLEXES HELP TO PREVENT INJURY: Explain the reflex action that would take place if you get a shock?

Answer 30

- your body releases the hormone adrenaline automatically - it doesn't wait for you to decide that you're shocked

Question 31

What is a reflex arc?

Answer 31

The passage of information in a reflex (from receptor to effector)

Question 32

What it the passage of information in a reflex called?

Answer 32

a reflex arc

Question 33

REFLEX ARCS GO THROUGH THE CNS: Where do the neurones in reflex arcs go through?

Answer 33

the spinal cord or an unconcious part of the brain

Question 34

REFLEX ARCS GO THROUGH THE CNS: What happens when a stimulus (e.g. a bee sting) is detected?

Answer 34

impulses are sent along a sensory neurone to a relay neurone in the CNS

Question 35

REFLEX ARCS GO THROUGH THE CNS: What happens when the impulses reach a synapse between the sensory neurone and the relay neurone?

Answer 35

- they trigger chemicals to be released - these chemicals cause impulses to be sent along the relay neurone

Question 36

REFLEX ARCS GO THROUGH THE CNS: What happens when the impulses reach a synapse between the relay neurone and motor neurone?

Answer 36

Chemicals are released and cause impulses to be sent along the motor neurone

Question 37

REFLEX ARCS GO THROUGH THE CNS: What do relay neurones do?

Answer 37

connect sensory neurones to motor neurones

Question 38

REFLEX ARCS GO THROUGH THE CNS: What happens after the impulses are sent along the motor neurone?

Answer 38

impulses travel along the motor neurone to the effector (which is usually a muscle) - the muscle will then contract

Question 39

Why are reflex actions quicker than normal responses?

Answer 39

you don't have to think about the response (which takes time)

Question 40

REQUIRED PRACTICAL 7- investigating reaction time: What is reaction time? What factors can it be affected by?

Answer 40

- the time it takes to respond to a stimulus (often less than a second) - age, gender , drugs

Question 41

REQUIRED PRACTICAL 7- investigating reaction time: Name three control variables of the experiment?

Answer 41

- use the same person to catch the ruler each time (make sure they always use the same hand to catch the ruler) - the ruler should always be dropped from the same height - make sure that the person being tested has not had any caffeine (or anything else that might affect their reaction time) on the day prior to the experiment

Question 42

REQUIRED PRACTICAL 7- investigating reaction time: Name another way that reaction times can be measured?

Answer 42

Simple computer tests can also be used to measure reaction time e.g. the person being tested has to click the mouse or press a key as soon as they see a stimulus on the screen ( such as a box change colour)

Question 43

REQUIRED PRACTICAL 7- investigating reaction time: What are 3 benefits to using a computer to measure reaction time?

Answer 43

- more precise reaction time measurement (no human error) - more accurate measurement (can record reaction time in milliseconds) - the person can't predict when to respond