Nervous System

Question 1

List the three structures involved in the protection of the central nervous system?

Answer 1

Bone, meninges, cerebrospinal fluid (CSF)

Question 2

What does the bone do?

Answer 2

It is the outermost protective later e.g. the cranium protects the brain and the vertebral canal protects the spinal cord

Question 3

What is the role of the meninges?

Answer 3

Are membraned formed by 3 layers of connective tissue, they cover the entire CNS;
Outer layer = tough & fibrous
Middle layer = loose mesh fibres
Inner layer = more delicate, contains blood vessels

Question 4

What is the role of the cerebrospinal fluid (CSF)?

Answer 4

Occupies the space in the middle layer of the meninges in there brain cavities and in the centre of the spinal cord. It is a clear watery fluid which contains cell some cells such as glucose. Formed from blood

Question 5

What are the three functions of the cerebrospinal fluid?

Answer 5

1. Transports nutrients to the brain and removes waste
2. Acts as a shock absorber by cushioning the CNS
3. Supports the brain as it floats in the CSF fluid

Question 6

What is the function of the cerebrum?

Answer 6

Involved in mental activities e.g. thinking, decision making, reasoning, learning, memory, intelligence and control of voluntary muscle contraction. left side is responsible for language ability, mathematics, logical thinking and decision making where as right side is responsible for musical/artistic ability

Question 7

What is the structure of the cerebrum?

Answer 7

Outer layer which is composed of grey matter followed by white matter composed of myelinated nerve fibres. It contains the basal ganglia which is deep inside and contains grey matter. Contains folding ridges –> convolutions which increase surface area. Separated into four lobes; parietal, frontal, temporal, occipital

Question 8

What is the cerebellum?

Answer 8

Second largest part of the brain. Folded outer surface which contains grey matter on the outside and white matter on the inside which branches to all parts of the cerebellum. It controls posture and balance and fine coordination of voluntary muscles. The control os unconscious

Question 9

What is the hypothalamus?

Answer 9

In the middle of the brain which controls many body activities and maintains homeostasis which regulates autonomic nervous system functions such as heart rate, blood pressure, temperate, food and water intake

Question 10

What is the medulla oblongata?

Answer 10

Nerve Fibres pass through medulla oblongata to or from the brain which regulates autonomic functions such as cardiac cycle, respiratory centre, vasomotor centre, and other reflexes such as swallowing, blinking,vomiting however all are controlled by higher centres such as the hypothalamus

Question 11

What is a neuron or nerve cell?

Answer 11

The basic structural and functional units of the whole nervous system the three main components of a neutron are dendrites, cell body and the axon

Question 12

What are multipolar neurons?

Answer 12

They are the most common, have 1 axon and multiple dendrites extending from the cell body. These include most inter neurones and motor neurons.

Question 13

What are bipolar neurons?

Answer 13

They have 1 axon and 1 dendrite, axon and dendrite may have branches on the ends these occur in the eye, ear, nose where they take impulses from the receptor cells to the other neurons

Question 14

what are unipolar neurons?

Answer 14

Unipolar neurons have 1 axon and the cell body is to one side of the axon, are most sensory neurons that carry messages to the spinal cord

Question 15

What is the difference between a nerve fibre and a nerve ?

Answer 15

A nerve fibre is any long extension of cytoplasm of a nerve cell boy, although the term i usually referred to as an axon. A nerve is a bundle of nerve fibres held together by connective tissue

Question 16

What is a synapse?

Answer 16

A small gap between one neuron and the next, which is transmitted in the form of a chemical message

Question 17

What are neurotransmitters?

Answer 17

special chemicals released from the axon which diffuse across the synapse –> dendrite–> cell body

Question 18

What is a neuromuscular junction?

Answer 18

Tiny gap between axon and muscle

Question 19

What is a reflex?

Answer 19

A rapid, autonomic response to a change in external or internal environment which is one ewe the body achieves homeostasis.

Question 20

What are the four properties of a reflex?

Answer 20

1. Stimulus: is required to trigger off a reflex, not spontaneous
2. Involuntary: occurs without any conscious thought
3. Rapid: Only a small number of neurons
4. Stereotyped: It occurs in the same way each time it happens

Question 21

What is the reflex arc or spinal reflex?

Answer 21

Name given to a pathway of nerve impulse from receptor to effector muscle. Impulses are sent to the brain after the response has taken place. They protect the body form injury e.g. sneezing, coughing, vomiting

Question 22

What is the spinal nerve?

Answer 22

Contains the dorsal root ganglion which conatins sensory neurons that have cell bodies and the ventral root which contains the axons of motor neurons

Question 23

What are the components of a reflex arc?

Answer 23

1. Sensory neuron - carries impulse from receptor to CNS
2. Receptor - end of sensory neuron receptor reacts to change
3. Effector - receives the impulse and carries out the appropriate response
4. Motor neuron - carries impulse to the effector
5. Synapse - there is at least one synapse impulse may pass direct to motor neurone or one or more inter neurons and then to motor neurones

Question 24

What is the role of the autonomic nervous system?

Answer 24

Part of the peripheral nervous system in which it controls the body’s internal environment. It is involved in homeostasis mechanisms that keep internal environment constant which usually operates without conscious control

Question 25

What of the somatic nervous system?

Answer 25

Part of the peripheral nervous system in which it controls voluntarily bodily movement and enables skeletal muscle movement

Question 26

What is the role of the sympathetic nervous system?

Answer 26

The primary function of the sympathetic system is to stimulate your fight-or-flight response which is a physiological reaction that happens in response to a perceived harmful event, attack or threat to survival

Question 27

What is the role of the parasympathetic nervous system?

Answer 27

The parasympathetic system enables you to maintain normal functions such as digesting and keeping the body at rest.

Question 28

What is the difference between the nervous and endocrine system?

Answer 28

The nervous sends messages in the form of electrical impulses and neurotransmitters along the membrane of neurones which are rapid where as endocrine system sends messages in the form of hormones by the bloodstream which affects all body cells and are slower - may take a few days to cause a response

Question 29

What is a nerve impulse?

Answer 29

The message travels along a nerve fibre which are transmitted quickly making it possible for the body to respond rapidly to any change in the internal or external enviroment

Question 30

What does a nerve impulse involve?

Answer 30

A nerve impulse is an electrochemical charge that travels along a nerve fibre - it involves a change in electrical voltage that is brought about by changes in the concentration of ions inside and outside the cell membrane

Question 31

How fast does a nerve impulse travel?

Answer 31

The speed at which a nerve impulse travels at depends whether the nerve fibre is myelinated and unmyelinated and also the diameter of the fibre

Question 32

How do nerve impulses travel in an unmyelinated fibre?

Answer 32

Travels steadily

Question 33

How does a nerve impulse travel in myelinated fibres?

Answer 33

Myelin sheath is not continuous puntured my gaps called the nodes of ranvier in which nerve impulses jump from one node to the next -> saltatory conduction which allows the nerve impulse to travel faster.