B10 The Nervous System

Question 1

What is homeostasis?

Answer 1

Maintenance of constant internal environment in order to maintain optimal conditions for enzyme and cellular functions

Question 2

The conditions maintained by homeostasis in the body

Answer 2

Blood glucose concentration
Water levels
Body temperature

Question 3

What 2 types of responses are used in body control system?

Answer 3

Nervous and Chemical responses

Question 4

What 3 components do all control systems have

Answer 4

Receptors
Coordination centre
Effector

Question 5

What is the function of a receptor?

Answer 5

Detect changes in the environments (stimuli)

Question 6

What is the function of a coordination centre?

Answer 6

obtain and process information from the receptors

Question 7

What is the function of an effector?

Answer 7

Bring about responses to stimuli

Question 8

What is the function of the Nervous System?

Answer 8

Allow body to react to surroundings and coordinate an appropriate response

Question 9

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

Answer 9

Stimulus is converted into a electrical impulse by the receptors
Electrical impulse passes along sensory neurone to the central nervous system
The CNS coordinates an appropriate response and an electrical impulse is sent along motor neurone to the effector which carries out the response

Question 10

What sequence of events describes how the nervous system works?

Answer 10

Stimulus —–> Receptor —–> Coordinator —–> Effector —–> Response

Question 11

What is a reflex action?

Answer 11

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

Question 12

Why are reflex actions important?

Answer 12

Aid survival by preventing harm from the body

Question 13

Describe how a reflex action occurs via a reflex arc

Answer 13

Stimulus is detected by a receptor
An electrical impulse passes along a sensory neurone to the spinal cord
At the 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
The same process occurs at the synapse between a relay neurone and a motor neurone
At the effector an appropriate response is carried out

Question 14

What is the difference between a reflex pathway and a conscious pathway?

Answer 14

Within a reflex pathway the coordination centre is a relay nueron found in the spinal cord/unconscious parts of the brail. In a conscious pathway, the coordination centre is in the conscious part of the brain

Question 15

What is the function of the cerebral cortex?

Answer 15

Controls consciousness, intelligence, memory and language

Question 16

What is the function of the cerebellum?

Answer 16

Controls muscular coordination

Question 17

What is the function of the medulla?

Answer 17

Controls unconscious activiets eg. breathing , heart rate

Question 18

Why is the investigation and treatment of the brain difficult?

Answer 18

The brain is a complex and delicate organ
The brain is easily damages and destroyed
Certain membrane prevent drugs from reaching the brain
The exact function of each part of the brain is not known

Question 19

What methods are used by scientist to determine brain function?

Answer 19

Studying patients with brain damage
Electrical stimulation of the brain
MRI scans

Question 20

What stimuli are the receptors of the eyes sensitive to?

Answer 20

Light intensity and colour

Question 21

What are the two main functions of structures found within the eye?

Answer 21

Focusing on near or distant objects
Adaptation to dim light

Question 22

Describe the structure and function of the retina

Answer 22

The retina is a light sensitive layer found at the back if the eyes
Light stimulates the retinal cells resulting in impulses sent to the brain

Question 23

Describe the structure and function of the optic nerve

Answer 23

Connects the eye and the brain
It carries impulses to the brain so that and image can be visualised

Question 24

Describe the structure and function of the sclera

Answer 24

The thought outer ayer of the eye which protects its internal structures

Question 25

Describe the structure and function of the cornea

Answer 25

Curved transparent layer at the front of the eye It lets light into the eye and allows light to be focused onto the retina

Question 26

Describe the structure and function of the iris

Answer 26

A muscle which controls the size of the pupils but contracting or relaxing. this allows the eye to adjust to bright and dim lighting

Question 27

Describe the structure and function of the ciliary muscles and suspensors ligaments

Answer 27

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

Question 28

Describe how the iris alters size of the pupils in both bright and dim light

Answer 28

Bright light: circular muscles contact and radial muscles relax- makes pupil smaller to avoid retinal damage Dim light: circular muscles relax and radial muscles contract- malke pupil larger so more light can enter the eye

Question 29

What is accommodation?

Answer 29

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

Question 30

How does the eye focus on a nearby object?

Answer 30

Ciliary muscles contract Suspensory ligaments loosen Lens becomes thicker and more curved-light rays are refracted strongly

Question 31

How does the eye focus on a far away object?

Answer 31

Ciliary muscles relax Suspensory ligaments tighten Lens becomes thinner- light rays are refracted weakly

Question 32

What is myopia?

Answer 32

Short-sightedness that usually occurs when the lens of the eye is too curved. As a result light is focused in form go the retina so images appear blurry

Question 33

How can myopia be treated?

Answer 33

By using glasses with a concave lensw, which spreads out light rays so they can ve focused on the retina

Question 34

What is hyperopia?

Answer 34

Long sightedness that 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

Question 35

How can hyperopia be treated?

Answer 35

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

Question 36

What are the two types of contact lenses?

Answer 36

Contact lenses are lenses that are placed on the eye. There are two types: Hard- rigid material, last a long time, must be kept sterile Soft- flexible material, lasts for a shorter time, more comfortable

Question 37

What is laser eye surgery?

Answer 37

The uses of lasers to fix visual defects in adults. to treat 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 correctly

Question 38

How can replacement lenses be used to treat visual defects?

Answer 38

Can either implant into the eye ( along with the natural lens) or it may replace the natural lens altogether .

Question 39

What are the risk of lens replacement?

Answer 39

Risks of lens replacement include retinal damage, cataracts and infections

Question 40

Where is body temperature controlled in the body?

Answer 40

By the thermoregulatory centre in the hypothalamus of the brain

Question 41

How is temperature monitored by the body?

Answer 41

Thermoregulatory centre has receptors sensitive to blood temperature. Skin has receptors sensitive to skin temperature- sends impulses to thermoregulatory centre

Question 42

What physiological changes occur when the body temperature is too high?

Answer 42

Vasodilation- blood vessels near the surface of the skin dilate- more heat is radiated away Sweating- evaporation of water takes heat energy form the surface of the skin

Question 43

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

Answer 43

Vasoconstriction - blood vessels near the surface of the skin constrict - less heat radiated away Shivering - respiration allow muscles to contract. It is an exothermic process, so heat energy is released. Sweating stops