B5 Nervous System/Eyes

Question 1

What is the central nervous system

Answer 1

Consists of the spinal cord and brain. Connects the body to neurones.

Question 2

Definition

Sensory/Motor/Relay neurones
Effectors

Answer 2

Sensory-Neurones that carry information as electrical impulses to CNS from receptors
Motor-Neurones that carry electrical impulses from CNS to effectors
Relay-Neurones that connect the sensory and motor neurones
Effectors-All muscles and glands which respond to nervous impulses

Question 3

Definition

Receptors

Answer 3

These are the cells that detect stimuli

Question 4

Definition

Reflex

Answer 4

Rapid automaic involuntary response to certain stimuli to reduce chances of getting injured.

Question 4

Describe the path of a reflex arc when a hand touches something hot

Answer 4

Receptors in the hand detect the stimuli which is heat. Information is converted into electrical impulses in the sensory neurone as it trnasfers the electrical impulses to the central nervous system. The spinal cord then coordinates a response.
Then central nervous system transmits electrical impulses to the relay neurone. The electrical impulses are carried to motor neurones. The electical impulse cause the muscles in the hand to contract and move away from the hot object

Question 5

What is a synapse and what occurs between it

Answer 5

Synapse is the space between 2 neurones. The nerve signal is transferred by chemicals which diffuse across the gap.

Question 6

Draw the brain and explain each part

Answer 6

Cerebral cortex-Responsible for things like consciousness intelligence memory and language
Medulla-Unconscious activities like breathing and your heartbeat
Cerebellum-Responsible for muscle coordination
Hypothalamus-Regulating body temperature
Pituatary gland-Controls puberty
Brain stem

Question 7

Explanation

MRI
Advantages/Disadvantages

Answer 7

MRI-Magnetic resonance imaging. provides an image of the brain using non-invasive techniques.
Advantages-Non invasive/No ionising radiation/Safer than CT scans
Disadvantages-Person must stay still not suitable for small kids/Magnetic So people with metal implants unable to do it

Question 8

Explanation

CT
Advantages/Disadvantages

Answer 8

CT- Computed tomography scan uses X rays to make detailed images of the body. Diagnoses bone damage, internal organ damage, blood issues and cancer.
Advantages-Accurate diagnosis/Non invasive/Wide use
Disadvantages-Radiation Exposure/Cancer risk/Expensive/Pregnancy Concerns

Question 9

Explanation

EEG
Advantages/Disadvantages

Answer 9

EEG-Works by attaching small sensors over scalp to detect electrical signals.
Advantages-Detects epilepsy/Can ask patients what they feel when stimulated/No electricity put into body.
Disadvantage-Can’t detect cancer

Question 10

Name 3 procedures for the brain

Answer 10

Brain surgery-Necesarry for brain tumour but may cause brain damage/infection
Brain Implant-Can help brain function/Earlt stage Parkinsons disease and may have brain damage
Radiotherapy-Destroys tumors but can damage normal brain cells

Question 11

Draw eye and explain each part

Answer 11

Cornea- Transparent layer/Oxygen diffuses in. Allows light to refract.
Iris-Controls size of pupil
Pupil-Hole in iris allowing light to enter. Iris controls size of pupil.
Lens-changes shape/focuses light on retina
Retina- Rod cells detect black and white
Cone cells detect blue green red less sensitive.
Optic nerve- carries impulses from retina to brain
Cilliary muscles/Suspenosry ligaments-Control shape of lens

Question 12

What happesn to the iris in bright or dim light

Answer 12

In bright light the pupil must be smaller. The cicrular muscles contract and the radial muscles relax. reducing amount of light that can enter the eye.

In dim light the radial muscles contract and the circular muscles relax. To allow more light to enter

Question 13

Accomodation

Answer 13

Changing the shape of lens to see close or distant objects

Question 14

Hyperopia
Myopia

Answer 14

Hyperopia-Long sightedness the lens doesnt bend light enough or eyeball too short
Convex lens fixes this
Myopia-Short sightedness the lens refracts too much light or eyball too long.
Concave lens fixes this

Question 15

How does the lens change to view far/close objects

Answer 15

Near objects- Cillairy musscles contract which loosens the suspensory ligament.
Lens becomes more curved so increases amount of light it refracts into retina.
Far objects-Cilliary muscles relax which suspensory ligaments tighten.
Lens become less curved so refracts less light.