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biology gcse paper 2 > the human nervous system > Flashcards

the human nervous system Flashcards

1
Q

what is the function of the nervous system?

A

the nervous system allows the body to react to their surroundings and coordinate an appropriate response.

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2
Q

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

A

-stimulus —> receptor —> coordinator—> effector —> response
1. stimulus is detected by a receptor and converted into an electrical impulse
2. the electrical impulse passes along sensory neurones to the central nervous system (CNS)
3. the CNS coordinates an appropriate response and an electrical impulse is sent along motor neurones to the effector, which carries out the response

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3
Q

what is a reflex action?

A

an automatic and rapid response which does not involve any conscious input from the brain

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4
Q

why are reflex actions important?

A
  • aid survival by preventing harm to the body
  • reduce chance of injury
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5
Q

describe how a reflex action occurs via a reflex arc

A
  1. the stimulus is detected by a receptor
  2. an electrical impulse travels along a sensory neurone to the spinal chord (apart of the CNS)
  3. at a synapse between a sensory neurone and a relay neurone, a chemical diffuses across the gap which stimulates a new impulse which passes along the relay neurone
  4. the same process occurs at a synapse between a relay neurone and a motor neurone.
  5. at the effector, an appropriate response is carried out
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6
Q

describe a method for measuring reaction time (required practical)

A
  1. Sit down on the chair and place your forearm of your non-dominant hand on the table with your hand hanging over the end of the table.
  2. Have your partner hold the ruler in line so that the 0 mark is level with the top of your
    thumb.
  3. Your partner will drop the ruler without telling you beforehand, and you will catch the ruler as quickly as you can.
    4.Note and record the number level with the top of your thumb after you have caught the ruler
  4. Repeat the test at least 5 times.
  5. Swap places with your partner and repeat steps 1-5
  6. Find reaction times by using a conversion table to convert the ruler measurements.
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7
Q

what are the control variables for reaction time?

A
  • always measure the ruler at the top of the thumb
  • keep conditions of room same (lighting, level of bg noise)
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8
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 chord/unconscious parts of the brain.
In a conscious pathway, the coordination centre is in the conscious parts of the brain

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9
Q

what is the function of the cerebral cortex?

A

controls consciousness, intelligence, memory and language

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10
Q

what is the function of the cerebellum?

A

controls muscular coordination (movement)

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11
Q

what is the function of the medulla?

A

controls unconscious activities e.g. breathing, heart rate

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12
Q

why is the investigation of the brain difficult?

A
  • the brain is a complex, delicate organ
  • the brain is easily damaged and destroyed
  • certain membranes prevent drugs from reaching the brain
  • the exact function of each part of the brain is not known
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13
Q

what methods are used by scientists to determine brain function?

A
  • studying patients with brain damage
  • electrical stimulation of the brain
  • rMRI scans
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14
Q

what stimuli are the receptors of the eye sensitive to?

A

light intensity and colour

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15
Q

what are the 2 main functions of structures found in the eye?

A
  • focusing on near or distant objects - accommodation
  • adaptation to dim light
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16
Q

describe the function of the retina

A
  • the retina is a light sensitive layer found at the back of the eye
  • light stimulates the retinal cells, resulting in impulses being sent to the brain
17
Q

describe the structure and function of the optic nerve

A
  • the optic nerve connects the eye and the brain
  • it carries impulses to the brain so that an image can be visualised
18
Q

describe the structure and function of the sclera

A

the sclera is a tough outer layer of the eye which protects its internal stuctures

19
Q

describe the structure and function of the cornea

A
  • the cornea is a curved transparent layer at the front of the eye
  • it lets light into the eye and allows light to be focused onto the retina
20
Q

describe the structure and function of the iris

A
  • a muscle which controls the size of the pupil by contracting or relaxing
  • this allows the eye to adjust to bright and dim lighting
21
Q

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

A

the ciliary muscles and the suspensory ligaments hold the lens in place and control its shape

22
Q

describe how the iris alters it’s size of the pupil in both bright and dim light

A
  • bright light —> circular muscles contract and radial muscles relax, makes pupil smaller to avoid retinal damage
  • dim light —> circular muscles relax and radial muscles contract, makes pupils larger so more light can enter the eye
23
Q

what is accommodation?

A

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

24
Q

how does the eye focus on a nearby object?

A
  • ciliary muscles contract so they have a smaller diameter
  • suspensory ligaments loosen
  • lens becomes thicker and more curved- light rays are refracted strongly
25
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
26
Q

what is myopia?

A

myopia (short sightedness) usually occurs when the lens of the eye is too curved.
As a result, light is focused in front of the retina so images appear blurry

27
Q

how can myopia be treated?

A

treated using glasses with a concave lens, which spreads out light rays so they can be focused on the retina

28
Q

what is hyperopia?

A

hyperopia (long sightedness) usually occurs when the lens of the eye is too flat. As a result, light is focused behind the retina so images appear out of focus

29
Q

how is hyperopia treated?

A

hyperopia can be rested using glasses with a convex lens, which brings the light rays together so they can be focused on the retina

30
Q

what are the two types of contact lenses?

A
  1. Hard- rigid material, last a long time, must be kept sterile
  2. Soft- flexible material, last for a shorter time, more comfortable
31
Q

what is a laser eye surgery?

A

Laser eye surgery is the use of layers to fix the visual defects in adults. To rest myopia, lasers reduce the thickness of the cornea so light is refracted less strongly. To treat hyperopia, lasers alter the curvature of the cornea so that light is refracted strongly

32
Q

how can replacement lenses be used to treat visual defects?

A

a replacement lens can either be implanted into the eye (along the natural lens) or it may replace the natural lens altogether.

33
Q

what are the risks of lens replacement?

A

Retinal damage, cataracts and infections

34
Q

where is body temperature controlled in the body?

A

body temperature is controlled in the thermoregulatory centre in the hypothalamus of the brain

35
Q

how is body 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
36
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
37
Q

what physiological changes occur when the body temperature is too low?

A
  • vasoconstriction- blood vessels near the surface of the skin constrict - less heat radiated away
  • shivering - respirations allows muscles to contract. It is an ex other mic reaction so heat energy so released
  • sweating stops

biology gcse paper 2 (4 decks)

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