B3.1 The Nervous system - Structure & Function

Question 1

<p>What is the function of the nervous system?</p>

Answer 1

<p>To detect changes in the environment and respond to these changes to maintain homeostasis.</p>

Question 2

<p>State the name given to a change in environment</p>

Answer 2

<p>Stimulus</p>

Question 3

<p>Name the group of cells responsible for detecting a stimulus?</p>

Answer 3

<p>Sensory receptors</p>

Question 4

<p>Where are receptor cells generally found?</p>

Answer 4

<p>Sense organs</p>

Question 5

<p>Listsome common examples of sense organs an their stimulus.</p>

Answer 5

<ul> <li>Eye - Light</li> <li>Tongue -Chemical tastes (in food and drink)</li> <li>Nose -Chemical smells (in the air)</li> <li>Skin -Temperature, pressure and pain</li> <li>Ears - Sound</li></ul>

Question 6

<p>What is the name given to the cells that carry out the response?</p>

Answer 6

<p>Effectors</p>

Question 7

<p>State the two types of effectors giving an example response for each.</p>

Answer 7

<ol> <li>Muscles - respond by contracting</li> <li>Glands - respond by secretions</li></ol>

Question 8

<p>State the two key components of the nervous system.</p>

Answer 8

<ul> <li>Central nervous system (CNS)</li> <li>Peripheral nervous system (PNS)</li></ul>

Question 9

<p>State the key components of the nervous system.</p>

Answer 9

<ul> <li>Brain</li> <li>Spinal cord</li> <li>Nerves</li></ul>

Question 10

<p>Define the central nervous system.</p>

Answer 10

<ul> <li>The CNS is composed of the brain and spinal cord</li> <li>The brain is only involved in voluntary actions</li> <li>The spinal cord is invovled in both voluntart and involuntary actions</li></ul>

Question 11

<p>Define the peripheral nervous system.</p>

Answer 11

<ul> <li>The PNS is composed of the nerve cells that carry information to and from the CNS</li> <li>The spinal cord is invovled in both voluntart and involuntary actions</li></ul>

Question 12

<p>List the three main types of nerve cell including their pathway.</p>

Answer 12

<ol> <li>Sensory – The neurones that carry information as electrical impluses from the receptors in the sense organs to the CNS</li> <li>Relay – The neurones that carry electrical impulses from sensory neurones to motor neurones. They are found in the CNS.</li> <li>Motor – The neurones that carry electrical impulses from the CNS to the effectors</li></ol>

Question 13

<p>What is meant by the direction of impulse?</p>

Answer 13

<ul> <li>The direction in which a signal travels through a nerve</li></ul>

Question 14

<p>What type of signal is transmited by the nervous system?</p>

Answer 14

<p>Electrical</p>

Question 15

<p>State the difference between a nerve and a neurone.</p>

Answer 15

<ul> <li> <p>Neurones are specialized cells that conduct electrical impulses through the body.</p> </li> <li> <p>A nerve is a bundle of many nerve fibres enclosed within a protective sheath.</p> </li> <li> <p>Nerve fibres are the long axons of neurones together with any associated tissues.</p> </li></ul>

Question 16

<p>Write out a pathway for a 'voluntary action'.</p>

Answer 16

<p>Stimulus→ Receptor cells→ Sensory neurone→ Spinal cord→ Brain→Spinal cord→ Motor neurone→ Effector→ Response</p>

Question 17

<p>What is menat by a '<em>coordinated</em>' response?</p>

Answer 17

<p>The ability of the brain to process information from many sensory receptors simultaneously and send a series impulses to different parts of the body to produce the required actions.</p>

Question 18

<p>State the direction of impulse through the neurone with reference tolabels.</p>

Answer 18

<p>Impulse travels from the dendrites through neurone to axon terminals</p>

Question 19

<p>Name and label the neurone</p>

Answer 19

<p>Motor neurone</p>

<ol> <li>Dendrites</li> <li>Cell body</li> <li>Axon</li> <li>Axon terminals</li></ol>

Question 20

<p>Name the cell type that surrounds the axon of certain neurones and their purpose.</p>

Answer 20

<ul> <li>Cell type - Schwann's cells</li> <li>Collectively they form the myelin sheath</li> <li>The myelin sheath insulates the axon and increase the speed of transmission</li> <li>Gaps between these cells = nodes of Ranvier</li></ul>

Question 21

<p>Where would you expect to find a synapse?</p>

Answer 21

<p>Between the axon terminals of the pre-synaptic neurone, and the dendrites of the post-synaptic neurone.</p>

Question 22

<p>What is another term given to the gap between the axon terminals of the pre-synaptic neuroneand the dendrites of the post-synaptic neurone.</p>

Answer 22

<p>Synaptic cleft.</p>

Question 23

<p>Name to mode of transmission within a synaptic cleft.</p>

Answer 23

<p>Chemical.</p>

Question 24

<p>Explain the pathway of transmision fromaxon terminals pre-synaptic neuroneto post-synaptic neurone.</p>

Answer 24

<ol> <li>Electrical signal arrives ataxon terminals of the pre-synaptic neurone.</li> <li>Vesicles containing neurotransmitters stimulated.</li> <li>Neurotransmitters difuse out ofpre-synaptic neurone into synaptic cleft.</li> <li>Neurotransmitters difuse acrosssynaptic cleft.</li> <li>Neurotransmitters difuse into dendrites of the post-synaptic neurone</li> <li>Electrical signal triggered by neurotransmitters in the post-synaptic neurone</li></ol>

<p>e.g electrical→ chemical→ electrical</p>

Question 25

<p>Which organelle would you expect in abundance in the neurones?</p>

Answer 25

<p>Mitochondria to provide energy.</p>

Question 26

<p>Describe the difference in a voluntary and reflex action.</p>

Answer 26

<ul> <li>Voluntary actions involve conscious thought</li> <li>Reflex actions are automatic (involuntary) reactions, they are unconscious missing out the brain, occuring without thinking.</li></ul>

Question 27

<p>State the reflex that protects the retina in changing light intensities</p>

Answer 27

<p>Pupil reflex</p>

Question 28

<p>Explain how your body responds to stepping on a sharp stone from stimulus to response.</p>

Answer 28

<ol> <li>Stimulus - stepping on stone</li> <li>Receptor - pressure receptors in the skin</li> <li>Electrical impulse transmitted through sensory neurone to spinal cord</li> <li>Electrical impulse transmitted through motor neurone to muscles in thigh of the leg.</li> <li>Effector - themuscles in thigh of the leg lift the leg to move away from the object in response.</li></ol>