Nervous system and eye

Question 1

CNS

Answer 1

Brain and spinal cord
\
Processing centre of nervous system

receives information from and sends info to PNS

Question 2

PNS

Answer 2

Cranial nerves from brain, spinal nerves from brain

communication relay going back and forth between CNS and rest of the body

Question 3

Difference between nervous system and endocrine system (6)

Answer 3

N: Involve nerve impulse
E: Involve hormones (chemicals)

N: Impulse transmitted by neurons
E: Hormones transported by blood

N: Quick response
E: Slow response

N: Response short-lived
E: Response may be short lived or long lived

N: May be voluntary or involuntary
E: Always involuntary

N: Usually localised
E: May affect more than one target organ

Question 4

Sensory neuron structure and function

Answer 4

conducts impulses from receptor to CNS

Long dendron short axon

Question 5

Relay Neuron

Answer 5

Found between sensory and motor neurons

transmit impulses upwards to brain or downwards from brain, along spinal cord

Question 6

Why relay neuron no myelin sheath

Answer 6

nerve impulses dont need to speed up as it only conducts nerve impulses over a short distance

Question 7

Axon function and structure

Answer 7

Long axon and various short dendrons projecting from cell body

transmits nerve impulses from CNS to effectors

Question 8

Function of Myelin Sheath

Answer 8

acts as an insulator for nerve impulses, allowing them to be sped up at Node of Ranvier

Provide nourishment for cell

Question 9

Node of Ranvier function

Answer 9

Speed up transmission of impulses

Question 10

Neurotransmitter

Answer 10

Chem substance that is released at synapse to help in transmission of impulse across synapse

Question 11

What does white matter consists of in spinal chord

Answer 11

mainly nerve fibres

Question 12

What does grey matter consists of in spinal chord

Answer 12

mainly cell bodies

Question 13

What provide nutrients to spinal cord

Answer 13

cerebriospinal fluid

Question 14

ventral root conatains ____

Answer 14

motor neurons

Question 15

dorsal roots conatain ___-

Answer 15

sensory neurons

Question 16

Cell bodies of motor neurons found in _____ while cell bodies of sensory neurons found in _________

Answer 16

grey matter

dosal root gangalion

Question 17

Whats a reflex action

Answer 17

A rapid response to a specific stimulus without conscious control

Question 18

Whats a reflex arc

Answer 18

Shortest pathway by which impulses travel from receptor to effector in reflex action

Question 19

When your hand touch hot object, what happens

Answer 19

1. Nerve endings in skin stimulated
2. Nervous impulses are initiated by receptors
3. Nervous impulses travel along dendron of sensory neuron to spinal cord
4. In spinal cord, impulses transmitted across synapse to relay neuron
5. Impulses are transmitted across another synapse to motor neuron
6. impulses leave spinal cord
7. Impulses travel along axon to bicep muscles (effector) which contracts to cause hand to withdraw

Question 20

Conjuctiva

Answer 20

Transparent membrane covering exposed part of eye

Question 21

Pupil

Answer 21

Allow light to enter eye

Question 22

Sclera

Answer 22

Tough outermost layer that protect eyeball

Question 23

Chloroid

Answer 23

Contains network of blood cap supplying nutrients to eyes

pigmented black to prevent internal reflection of light within eyeball

Question 24

Aqueous hunour

Answer 24

Watery fluid that helps maintain shape of eyeball, refracts light onto retina

Question 25

cilliary muscle

Answer 25

Contract and relax to focus near and distant object

Question 26

Iris

Answer 26

Pigmented region which controls the amt of light entering the eye

Question 27

suspensory ligament

Answer 27

Attach edge of lens to cilliary muscle

Question 28

Vit hymour

Answer 28

maintain eyeball shape, reflect light to retine

Question 29

cORNEA

Answer 29

Transparent bulge at the front of eyeball where most of refraction of light occur

Question 30

Lens

Answer 30

change in curvature to focus on near and far objects

Question 31

Optic nerve

Answer 31

Relay nervous impulse from phtoreceptors in retina to brain

Question 32

Blind spot

Answer 32

No photoreceptors, wher eoptic nerve is located

Question 33

FOvia centralis

Answer 33

Highest conc of photorecep, region where images most focused and give sharpest vision

Question 34

Retina

Answer 34

Contain photoreceptors

Question 35

Accommodation of near vision

Answer 35

cilliary muscles contract –> sus liga slacken –> less pull on lens –> lens become thicker, more convex –> light rays from near objects focus on retina

Question 36

Accommodation of far vision

Answer 36

cilliary muscles relax –> sus liga tighten –> more pull on lens –> lens become thinner, less convex –> light rays from far objects focus on retina

Question 37

Bright light pupil reflex

Answer 37

circular muscle contract
radial muscle relax
Less light enter to protect retina

Question 38

Dim light pupil reflex

Answer 38

circular muscle relax
radial muscle contract
More light enter to Stimulate retina

Question 39

Nervous pathway - pupil reflex

Answer 39

1) Changes in light intensity stimulate retina
2) Nervous impulses are sent to the brain via the optic nerve
3) The brain interpret these impulses and send impulses via motor neurons to circular and radial muscles in iris
4) Muscles in iris contract and relax accordingly to ensure correct amt of light enter eye

Note: Even though brain is involved, pupil reflex happens without conscious control

Question 40

Benefit of binocular vision

Answer 40

good perception of depth and 3d images as the two eyes have overlapping fields of view