T5 human nervous system Flashcards Preview

aqa gcse biology free > T5 human nervous system > Flashcards

Flashcards in T5 human nervous system Deck (36)
Loading flashcards...
1
Q

function of the nervous system

A

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

2
Q

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

A

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

3
Q

what sequence of events describes how the nervous system work

A

Stimulus → receptor → coordinator →

effector → response

4
Q

what is a reflex action

A

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

5
Q

why are reflex actions important

A

aid survival by preventing harm to the body

6
Q

describe how a reflex action occurs via a reflex arc

A

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

7
Q

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

A

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

8
Q

function of the cerebral cortex

A

controls consciousness, intelligence, memory and language

9
Q

function of the cerebellum

A

controls muscular coordination

10
Q

function of the medulla

A

controls unconscious activities

11
Q

why is the investigation and treatment of the brain difficult

A

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

12
Q

what methods are used to determine brain function

A

studying patients with brain damage

electrical stimulation of the brain

MRI scans

13
Q

what stimuli are the receptors of the eye sensitive to

A

light intensity and colour

14
Q

2 main functions of structures found within the eye

A

focusing on near or distant objections - accommodation

adaptation to dim light

15
Q

describe the structure and function of the retina

A

light-sensitive layer found at the back of eye

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

16
Q

describe the structure and function of the optic nerve

A

connects the eye and the brain

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

17
Q

describe the structure and function of the sclera

A

tough outer layer of the eye which protects its internal structures

18
Q

describe the structure and function of the cornea

A

curved transparent layer at the front of the eye

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

19
Q

describe the structure and function of the iris

A

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

allows the eye to adjust to bright or dim lighting

20
Q

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

A

hold the lens in place and control its shape

21
Q

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

A

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

22
Q

what is accommodation

A

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

23
Q

how does the eye focus on a nearby object

A

ciliary muscles contract

suspensory ligaments loosen

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

24
Q

how does the eye focus on a far away object

A

ciliary muscles relax

suspensory ligaments tighten

lens becomes thinner - light rays are refracted weakly

25
Q

what is myopia

A

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

26
Q

how can myopia be treated

A

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

27
Q

what is hyperopia

A

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

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

28
Q

how can hyperopia be treated

A

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

29
Q

two types of contact lenses

A

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

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

30
Q

what is laser eye surgery

A

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

31
Q

how can replacement lenses be used to treat visual defects

A

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

32
Q

risks of lens replacement

A

retinal damage, cataracts and infections

33
Q

where is body temperature controlled in the body

A

by thermoregulatory centre in the hypothalamus of the brain

34
Q

how is temperature monitored by the body

A

thermoregulatory centre has receptors sensitive to blood temperature

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

35
Q

what physiological changes occur when the body temperature is too high

A

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

36
Q

what physiological changes occur when the body temperature is too low

A

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