Nervous system and structure of the eye

Question 1

What is sensibility

Answer 1

The ability to detect or sense changes in the environment

Question 2

What are the two systems that control the body

Answer 2

nervous system
endocrine system

Question 3

What is a stimulus

Answer 3

A change in an organism’s surroundings

Question 4

What is a receptor

Answer 4

receptors detect stimuluses and transduce the stimulus’ energy into electrical impulses

Question 5

What is an effector

Answer 5

a muscle or gland that brings about a response to a stimulus

Question 6

What can the ear detect

Answer 6

vibrations, sound, spacial positioning

Question 7

What can the nose detect

Answer 7

chemicals in the air through nose chemoreceptors

Question 8

what is the function of the nervous system

Answer 8

The nervous system uses electrical impulses to bring about fast but short lived responses which enable organisms to react to their surroundings and co-ordinate their behaviour.

Question 9

what are the parts of the nervous system

Answer 9

CNS - central nervous system - brain, spinal cord
PNS - Peripheral nervous system- the rest

Question 10

What are neurones

Answer 10

Specialised cells which carry electrical impulses
There are three types:
* Motor
* Sensor
* autonomic
* relay???

Question 11

PRACTICE DRAWING NERVE CELLS MOTOR AND SENSORY

Question 12

What can influence reaction time?

Answer 12

• age
• sex
• physical fitness
• fatigue
• distraction
• alcohol
• whether the stimulus is auditory or visual
• diet
• drugs - stimulus or depressant

Question 13

What is a synapse

Answer 13

A gap where two neurones meet

Question 14

How do impulses travel synapses

Answer 14

chemicals called neurotransmitters are released by the first neurone which carries the electrical impulse which diffuses across the gap and makes the next neurone transmit an electrical impulse by attaching to receptors on its surface.

Question 15

PRACTICE STRUCTURE OF THE eye

Question 16

What is the function of the cornea

Answer 16

transparent surface, meaning refraction occurs to focus light on retina

Question 17

What is the function of the pupil

Answer 17

Hole in centre of iris through which light enters the eye

Question 18

What is the function of the retina

Answer 18

Contains light sensitive receptor cells called rods (which respond to low light intensity but not wavelength à black and white) and cones (which respond to different wavelengths but only work in high intensity light à colour). It is dark to absorb as much light as possible.

Reflects light onto the optic nerve

Question 19

What is the function of the optic nerve

Answer 19

Carries electrical impulses from the receptors along sensory neurones to the brain

Question 20

Fovea

Answer 20

Where most cone cells are found on the retina

Question 21

Ciliary muscle

Answer 21

Changing the shape of the lens by contracting which helps focus the light on the retina

Question 22

Suspensory ligaments

Answer 22

slacken or become taught changing the shape of the lens

Question 23

lens

Answer 23

A curved structure in the eye that bends the light entering the light through refraction and focuses it so that it hits the retina

Question 24

Iris

Answer 24

This regulates the amount of light that accesses the back of the eye. This can dilate (expands eye) or constrict so that the right amount of light can be received

Question 25

Sclera

Answer 25

This is the supporting wall of the eyeball

Question 26

blind spot

Answer 26

This is where the eye cannot see, because the light cannot be reflected by the retina if it hits the nerve.

Question 27

Conjunctiva

Answer 27

This is a transparent mucous membrane on the surface of the eyelids, which keeps the surface of the eye: moist lubricated protected from dust and can generate tears with glands

Question 28

What are reflex actions

Answer 28

rapid, automatic and involuntary response of the nervous system which do not involve the brain as they pass through a relay neurone Undergoes a reflex arc

Question 29

What is the order that impulses travel in a reflex action

Answer 29

1. A stimulus (heat) is received by a receptor 2. The receptor converts this information into an impulse. 3. This impulse is transmitted along a sensory neurone 4. This impulse is transmitted along a relay neurone 5. The impulse is transmitted along a motor neurone to an effector 6. Effector (arm muscle) brings about a response by the arm muscle contracting which pulls hand away from flame. Also known as reflex arc

Question 30

What are the different types of photoreceptors in the eye

Answer 30

On the retina - cones and rods

Question 31

What is the function of cones

Answer 31

colour vision - can detect primary colours r g b located in the fovea sensitive to high-light intensities

Question 32

What is the function of rods

Answer 32

responsible for night vision Sensitive to low light intensities around the periphery of the retina

Question 33

How can an image be seen

Answer 33

light refracts on the cornea and the lens onto the retina where it is reflected. Means image is inverted at first, but the brain flips the image

Question 34

What is accomodation

Answer 34

changes in the eye that allows us to see objects at different distances

Question 35

accommodation (near vision)

Answer 35

ciliary muscles contract, suspensory ligaments slacken leading to thick lens increasing the refraction of light

Question 36

Accommodation(distant vision)

Answer 36

ciliary muscles are relaxed, suspensory ligaments are tense and the lens are thin to allow for less refraction

Question 37

What changes in the eye with different light intensities and why

Answer 37

high light intensity → pupil constricts less light is absorbed to avoid damaging retina low light intensity → pupil expands This means that more light can be absorbed

Question 38

How does the pupil constrict/expand

Answer 38

pupil expands by zonular fibres tightening and ciliary muscles relaxing pupil constricts by zonular fibres relaxing and ciliary muscles contracting. Antagonistic muscles

Question 39

How are nerve cells adapted for their function

Answer 39

1. long 2. myelin sheath 3. can make many connections