B10 - The human nervous system

Question 1

What is homeostasis

Answer 1

staying alive - the regulation of internal conditions to respond to stimuli

Question 2

What is the main reason for maintaining specific conditions

Answer 2

to make sure enzymes work optimally

Question 3

What are three internal conditions that need to be controllled

Answer 3

Body temperature
- water content
- blood glucose concentration

Question 4

What are some stimuli the body must respond to

Answer 4

sunlight level
- temperature change
- eating a meal

Question 5

What are receptors

Answer 5

cells that detect stimuli

Question 6

What are coordination centres

Answer 6

areas that recieve and process the information from receptors. They send signals and coordinate the response of the body e.g. the brain, hormonal system, spinal cord, pancreas

Question 7

What are effectors

Answer 7

muscles or glands that bring about responses to stimuli

Question 8

How fast do nerve signals travel

Answer 8

between 1 and 120 metres per second

Question 9

Where are receptor cells usually gathered

Answer 9

in organs such as eyes and skin

Question 10

What happens after a stimulus is detected

Answer 10

stimulus -> receptor -> sensory neurone until the Central Nervous System -> relay neurones in CNS -> motor neurones to body parts -> effectors

Question 11

What does CNS stand for
- what is it

Answer 11

Central Nervous System
- brain and spinal cord

Question 12

What is a reflex action

Answer 12

an automatic, subconscious, quick response

Question 13

Why are reflexes useful

Answer 13

they can save the body from danger

Question 14

What part of the CNS do reflexes go through
- What is the path taken called

Answer 14

spinal cord
- reflex arc

Question 15

Why don’t reflex arcs go through the brain

Answer 15

quicker response

Question 16

What happens at the synapse

Answer 16

electrical impulses trigger release of chemicals that diffuse across and are picked up on the other side

Question 17

What are the five main parts of the brain

Answer 17

• cerebral cortex
• cerebellum
• medulla
• hypothalamus
• pituitary gland

Question 18

What is the cerebral cortex concerned with

Answer 18

consciousness, intelligence, memory and language

Question 19

What is the cerebellum concerned with

Answer 19

coordinating muscular activity and balance

Question 20

What is the medulla concerned with

Answer 20

unconscious activities e.g. movement of gut, heartbeat and breathing

Question 21

What are three ways we can understand the brain

Answer 21

studying people with brain damage
- stimulating parts of the brain
- MRI scans

Question 22

What does MRI stand for
- what does it do

Answer 22

Magnetic Resonance Imaging
- shows us which part of the brain has been affected

Question 23

What are some issues with understanding the brain

Answer 23

• easily damaged and destroyed
• behind the skull
• very complex
• don’t know much about it

Question 24

Where are the light sensitive cells in the eye located

Answer 24

retina

Question 25

What are the 9 main parts of the eye

Answer 25

- iris - lens - pupil cornea - sclera - suspensory ligaments - ciliary muscles - optic nerve - retina

Question 26

What is the sclera

Answer 26

the white outer layer of the eye

Question 27

What is the transparent part of the sclera known as - where is it

Answer 27

cornea - at the front

Question 28

What does the curved surface of the cornea do

Answer 28

let light in and focus it on the retina

Question 29

What does the iris do

Answer 29

control the size of the pupil to control the amount of light entering

Question 30

What happens when bright light hits the eye

Answer 30

circular muscles contract radial muscles relax pupil constricts

Question 31

What happens when dim light hits the eye

Answer 31

circular muscles relax radial muscles contract pupil dilates

Question 32

What happens to light after it passes the pupil

Answer 32

goes through the lens

Question 33

What holds the lens in place

Answer 33

suspensory ligaments and ciliary muscles

Question 34

What does the lens do

Answer 34

focuses light on the retina

Question 35

What happens when light hits the retina

Answer 35

light sensitive cells are stimulated which send impulses along sensory neurones in the optic nerve. The brain interprets these as a visual image

Question 36

What is the blind spot

Answer 36

the place on the retina where the optic nerve is

Question 37

What direction is the image formed on the retina

Answer 37

inverted

Question 38

What is the name for the lens changing to see near and far

Answer 38

accomodation

Question 39

How does the the lens focus a distant object

Answer 39

ciliary muscles relax, suspensory ligaments pulled tight, lens is made flat and thin

Question 40

How does the lens focus a near object

Answer 40

ciliary muscles contract, suspensory ligaments loosen, lens is thicker and more curved

Question 41

Why do many older people need reading glasses

Answer 41

accommodation becomes more difficlt

Question 42

What is the name for short-sightedness

Answer 42

myopia

Question 43

What is the name for long-sightedness

Answer 43

hyperopia

Question 44

What happens in myopia - what type of lens is it commonly treated with

Answer 44

light is focused in front of the retina - concave

Question 45

What happens in hyperopia - what type of lens is it commonly treated with

Answer 45

light is focused behind the retina - convex

Question 46

What are four common ways of overcoming myopia and hyperopia

Answer 46

- contact lenses - laser eye surgery - replacement lenses - glasses

Question 47

What are the main risks of lens replacement

Answer 47

damage to retina, cataracts, infections