The nervous system - Chapter 4

Question 1

Protection of the CNS

Answer 1

• bone
• meninges
• cerebrospinal fluid

Question 2

Dura mater

Answer 2

outer meningeal layer
- tough and fibrous, therefore protects the brain
- sticks closely to bones of the skull, but inside vertebral canal is not so fitting

Question 3

Arachnoid mater

Answer 3

middle meningeal layer
- a loose mesh of fibres

Question 4

Pia mater

Answer 4

inner meningeal layer
- far more delicate
- contains many blood vessels
- sticks closely to the surface of the brain and spinal cord

Question 5

Cerebrospinal fluid

Answer 5

• occupies the space between the middle and inner layers of meninges
• circulate through cavities of the brain and through centre of spinal cord
• clear watery fluid containing a few cells and some glucose, protein, urea and salts

Question 6

3 Functions of CSF

Answer 6

1.protection - acts as a shock absorber
2. support - the brain is suspended inside the cranium and floats in fluid
3. transport - it is formed from blood, circulating around and through CNS before re-entering the blood capillaries. during this it takes nutrients to cells of the brain and spinal cord and carries away their wastes.

Question 7

Cerebrum

Answer 7

largest part of the brain (outer surface is 2-4mm thick of grey matter)

Question 8

Grey matter

Answer 8

neuron cell bodies, dendrites and unmyelinated axons

Question 9

White matter

Answer 9

myelinated axons

Question 10

Longitudinal fissure

Answer 10

almost operates brain into two halves. at its base is the corpus callosum.

Question 11

3 Functional areas of cerebral cortex

Answer 11

1. sensory areas - interpret impulses from receptors
2. motor areas - control muscular movements
3. association areas - concerned with the intellectual and emotional processes

Question 12

Memory

Answer 12

pathways of nerve cells. when a memory is stored, new links are made between neurons or existing links are modified.

Question 13

Right and left hemisphere differences

Answer 13

in right handed people, the right frontal lobe is wider than the left and left occipital and parietal lobes are wider than right.
- language ability normally controlled by left hemisphere
- musical and artistic abilities are functions of right hemisphere

Question 14

Frontal lobe

Answer 14

thinking, problem solving, emotions, personality, language and control of movement.

Question 15

Parietal lobe

Answer 15

processing temperature, touch, taste, pain and movement.

Question 16

Occipital lobe

Answer 16

vision

Question 17

Temporal lobe

Answer 17

processing memories and linking them with senses. receives auditory information.

Question 18

Insula

Answer 18

recognition of different senses and emotions, addiction and psychiatric disorders.

Question 19

3 Types of tracts that occur in white matter:

Answer 19

1. tracts that connect various areas of the cortex within the same hemisphere
2. tracts that carry impulses between the left and right hemispheres
3. tracts that connect the cortex to other parts of the brain or spinal cord.

Question 20

Corpus callosum

Answer 20

• wide band of nerve fibres
• located underneath cerebrum at base of longitudinal fissure
• allow two sides of cerebrum to communicate as the nerve fibres cross from one cerebral hemisphere to the other

Question 21

Cerebellum

Answer 21

control over posture, balance and fine coordination of voluntary muscle movement.

Question 22

Where does the cerebellum receive sensory information from?

Answer 22

• the inner ear for info on posture and balance
• stretch receptors in skeletal muscles for info about length of muscle

*without cerebellum, movements would be spasmodic, jerk and uncontrolled.

Question 23

3 Components of the medulla oblongata

Answer 23

1. the cardiac centre, which regulates the rate and force of the heartbeat
2. respiratory centres, which control rate and depth of breathing
3. the vasomotor centre, which regulates the diameter of blood vessels.

Question 24

Ascending tracts

Answer 24

sensory axons that carry impulses upwards, towards the brain.

Question 25

Descending tracts

Answer 25

contains motor axons that conduct impulses downwards, away from the brain.

Question 26

Types of nerves

Answer 26

cranial nerves and spinal nerves

Question 27

Cranial nerves

Answer 27

• 12 pairs of nerves
• mixed nerves - contain fibres that carry impulses to and from the brain
  sensory fibres = fibres that carry impulses into the CNS
  motor fibres = carry impulses away from CNS

Question 28

Spinal nerves

Answer 28

• 31 pairs of spinal nerves arise from spinal cord
• mixed nerves
  ventral root = contains the axons of motor neurons that have their cell bodies in grey matter
  dorsal root = contains the axons of sensory neurons that have their cell bodies in a small swelling dorsal root (ganglion).

Question 29

PNS

Answer 29

afferent:
- somatic sensory
- visceral sensory

efferent:
- somatic division
- autonomic division – sympathetic and parasympathetic divisions

Question 30

Afferent division of PNS

Answer 30

carry impulses into CNS
somatic sensory - bring impulses from skin and muscles
visceral sensory - brung impulses from internal organs

Question 31

Efferent division of PNS

Answer 31

carry impulses away from CNS
somatic division - takes impulses from CNS to skeletal muscles
autonomic division - carries impulses from CNS to heart, involuntary muscles and glands. further divided into sympathetic and parasympathetic nervous systems