T5 human nervous system

Question 1

function of the nervous system

Answer 1

allows the body to react to its surroundings and coordinate an appropriate response

Question 2

how does a stimulus lead to a response being carried out by the body

Answer 2

stimulus is converted into an electrical impulse by the receptors

electrical impulse passes along sensory neurons to the CNS

CNS coordinates an appropriate response and an electrical impulse is sent along motor neurones to the effector which carries out the response

Question 3

what sequence of events describes how the nervous system work

Answer 3

Stimulus → receptor → coordinator →

effector → response

Question 4

what is a reflex action

Answer 4

automatic and rapid response which doesn’t involve any conscious input from the brain

Question 5

why are reflex actions important

Answer 5

aid survival by preventing harm to the body

Question 6

describe how a reflex action occurs via a reflex arc

Answer 6

stimulus is detected by a receptor

electrical impulses passes along a sensory neurone to the spinal chord

at a synapse between a sensory neurone and a relay neurone, a chemical diffuses across the gap and stimulates a new impulse which passes along the relay neurone

at the effector, an appropriate response is carried out

Question 7

what is the difference between a reflex pathway and a conscious pathway

Answer 7

within a reflex pathway, the coordination centre is a relay neurone found in the spinal cord/unconscious parts of the brain

in a conscious pathway, the coordination centre is in the conscious part of the brain

Question 8

function of the cerebral cortex

Answer 8

controls consciousness, intelligence, memory and language

Question 9

function of the cerebellum

Answer 9

controls muscular coordination

Question 10

function of the medulla

Answer 10

controls unconscious activities

Question 11

why is the investigation and treatment of the brain difficult

Answer 11

brain is complex and delicate

easily damaged and destroyed

certain membranes prevent drugs from reaching the brain

exact function of each part of the brain is unknown

Question 12

what methods are used to determine brain function

Answer 12

studying patients with brain damage

electrical stimulation of the brain

MRI scans

Question 13

what stimuli are the receptors of the eye sensitive to

Answer 13

light intensity and colour

Question 14

2 main functions of structures found within the eye

Answer 14

focusing on near or distant objections - accommodation

adaptation to dim light

Question 15

describe the structure and function of the retina

Answer 15

light-sensitive layer found at the back of eye

light stimulates the retinal cells, resulting in impulses being sent to the brain

Question 16

describe the structure and function of the optic nerve

Answer 16

connects the eye and the brain

carries impulses to the brain so that an image can be visualised

Question 17

describe the structure and function of the sclera

Answer 17

tough outer layer of the eye which protects its internal structures

Question 18

describe the structure and function of the cornea

Answer 18

curved transparent layer at the front of the eye

lets light into the eye and allows light to be focused onto the retina

Question 19

describe the structure and function of the iris

Answer 19

muscle which controls the size of the pupil by contracting or relaxing

allows the eye to adjust to bright or dim lighting

Question 20

describe the structure and function of the ciliary muscles and suspensory ligaments

Answer 20

hold the lens in place and control its shape

Question 21

describe how the iris alters the size of the pupil in bright and dim light

Answer 21

B: circular muscles contract and radial muscles relax - makes pupil smaller to avoid retinal damage

D: circular muscles relax and radial muscles contract - makes pupil larger so more light can enter the eye

Question 22

what is accommodation

Answer 22

alteration of the lens shape in order to focus on near or distant objects

Question 23

how does the eye focus on a nearby object

Answer 23

ciliary muscles contract

suspensory ligaments loosen

lens becomes thicker and more curved - light rays are refracted strongly

Question 24

how does the eye focus on a far away object

Answer 24

ciliary muscles relax

suspensory ligaments tighten

lens becomes thinner - light rays are refracted weakly

Question 25

what is myopia

Answer 25

short-sightedness - usually occurs when the lens of the eye is too curved

light is focused in front of the retina so images appear blurry

Question 26

how can myopia be treated

Answer 26

glasses with a concave lense which spreads out light rays so they can be focused on the retina

Question 27

what is hyperopia

Answer 27

long-sightedness - occurs when the lens of the eye is too flat

light is focused behind the retina so images appear out of focus

Question 28

how can hyperopia be treated

Answer 28

glasses with a convex lense which brings the light rays together so they can be focused on the retina

Question 29

two types of contact lenses

Answer 29

hard - rigid material, last a long time, must be kept sterile

soft - flexible material, last for a shorter time, more comfortable

Question 30

what is laser eye surgery

Answer 30

use of lasers to fix visual defects in adults

m - lasers reduce the thickness of the cornea so light is refracted less strongly

h - lasers alter the curvature of the cornea so that light is refracted correctly

Question 31

how can replacement lenses be used to treat visual defects

Answer 31

can be implanted into the eye (along with natural lens) or it may replace the natural lens altogether

Question 32

risks of lens replacement

Answer 32

retinal damage, cataracts and infections

Question 33

where is body temperature controlled in the body

Answer 33

by thermoregulatory centre in the hypothalamus of the brain

Question 34

how is temperature monitored by the body

Answer 34

thermoregulatory centre has receptors sensitive to blood temperature

skin has receptors sensitive to skin temperature - sends impulses to thermoregulatory centre

Question 35

what physiological changes occur when the body temperature is too high

Answer 35

vasodilation - blood vessels near the surface of the skin dilate, more heat is radiated away

sweating - evaporation of water takes away heat energy from the surface of the skin

Question 36

what physiological changes occur when the body temperature is too low

Answer 36

vasoconstriction - blood vessels near the surface of the skin contract, less heat is radiated away

shivering - respiration allows muscles to contract, exothermic so heat energy is released

sweating stops