Nervous System

Question 1

What is the main function of the nervous system?

Answer 1

Control and co-ordination which is fast,generally short lived responses,electrically mediated

Question 2

What are the cellular elements of the nervous system

Answer 2

-neurons
-glial cells(sticky)
>there is more than neurons ratio is between 3:1 to 10:1
>there are several subtypes
>their role is to nurture neurons
>sham cells are an example of glial cells

Question 3

What are the types of glial cells

Answer 3

-ependymal cells
-microglia
-astrocytes
-obigodendrocytes

Question 4

Ependymal cells

Answer 4

E.g line ventricles and assist in production of CFS(cero spinal fluid)

Question 5

Microglia

Answer 5

-Remove debris and waste by phagocytosis
-can be considered as the immune cells
-they are scattered throughout the grey and white matter
-can release cytokines

Question 6

Astrocytes

Answer 6

-blood brain barrier
-absorb/recycle neurotransmitters
-also responsible for homeostatic processes such as ensuring the right concentrations of minerals such as potassium exist in order to prevent neurons from depolarising

Question 7

Neurons

Answer 7

-functional units of the nervous system
-main function is to process information
-there are 3 main regions
>cells body ands dendrites( inputs which receive the information)
>Axon(transmission)
>Axon terminals(outputs eg contacting another cell)
-all the functions are mediated by neuronal membrane functions which are dependant on membrane potential

Question 8

How are neurons classified

Answer 8

-Because neurons are very diverse they are classified based on their structure eg uni,multi,bipolar
-can also be classified due to their functions

Question 9

List all the neuronal pools

Answer 9

-divergence
-convergence
-serial processing
-parallel processing
-reverberation

Question 10

Divergence

Answer 10

-spread of information to several neurons
-eg significant divergence of sensory information reaching different parts of the nervous system

Question 11

Convergence

Answer 11

Several neurons synapse On a single neurone
Eg voluntary breathing vs breath holding

Question 12

Serial processing

Answer 12

-Stepwise processing of information
-nociceptive pathways

Question 13

Parallel processing

Answer 13

-several neurons receive the same information so divergence must occur
-eg stepping on a pin -for moves, weight moves,sense of pain

Question 14

Reverberation

Answer 14

-positive feedback loop(amplifying change)
-eg Maintenance of wakefulness

Question 15

Organisation of the nervous system

Answer 15

-Nervous system is divided into central nervous system and peripheral nervous system
-central nervous system is divided into the brain and
The spinal cord
-peripheral nervous system is divided into afferent and efferent
-efferent is divided into somatic and autonomic
-autonomic is divided into the sympathetic and parasympathetic
-afferent is somatic and visceral

Question 16

Parts of the nervous system

Answer 16

Brain
Spinal cord

Question 17

What are the layers protecting the brain

Answer 17

Skull
Bone
Meninges
Csf

Question 18

Name the lobes of the brain

Answer 18

-frontal lobe(front)
-temporal lobe(side)
-occipital lobe(back)
-parietal lobe(top)

Question 19

Divisions of the brain

Answer 19

-medulla
-pons
-midbrain
-limbic system
-diencephalon
-cerebrum
-cerebellum

(Increases in complexity)

Question 20

The brain stem (medulla,pons,midbrain)

Answer 20

-very old
-basic functions include the respiratory rhythm , blood pressure regulation and vomiting
-origin of cranial nerves
-midbrain constitutes part of the reticular formation eg maintenance of wakefulness as well as some aspects of visual and auditory processing

Question 21

What are cranial nerves

Answer 21

-12 cranial nerves
-all innervate head and neck except the vagus nerve which is parasympathetic

Question 22

Parts of the diencephalon

Answer 22

Thalamus and hypothalamus

Question 23

Thalamus

Answer 23

-final relay point for sensory information that will br transmitted to the cortex =acts as a filter eg does the information need to go to the brain?

Question 24

Hypothalamus

Answer 24

• Controls and integrates activity of the ANS
• Controls the pituitary gland (release hormones) and releases its own
hormones
• Regulates emotional and behavioural patterns e.g. eating and drinking
• Controls body temperature
• Subconscious control of skeletal muscle in relation to behavioural patterns
e.g. rage, aggression, pain
• Coordination between voluntary and autonomic functions e.g. increased HR
when thinking about dangerous situations
• Contains the suprachiasmatic nucleus which controls circadian rhythms.

Question 25

Functions of the cerebellum

Answer 25

• Electrical stimulation = no loss of sensation or movement • However, loss of cerebellum = significant motor abnormalities • Overall, role in controlling postural muscles and rapid muscular activity e.g. typing, playing a musical instrument • Inputs –motor cortex, vestibular system, proprioceptors • Outputs –via thalamus to motor cortex and premotor cortex and to vestibular nuclei and reticular formation

Question 26

What does the cerebellum do?

Answer 26

• Supplement motor activity – particularly control of posture and correcting rapid movements initiated in motor cortex (comparator) • Motor learning eg shoe laces • Much of what we know comes from damage • Staggering walk and difficulty standing –cerebellar ataxia • Loss of coordination (asynergia) and muscle tone (hyptonia)

Question 27

Cerebrum

Answer 27

• Separated into two cerebral hemispheres by the longitudinal fissure, each hemisphere divided into four lobes • Hemispheres connected by the corpus callosum • Outermost layer of each hemisphere is the cortex, below which is the white matter. • The cortex enlarges at a greater rate than the underlying white matter – hence its convoluted appearance. Peaks are called Gyri, troughs are called Sulci

Question 28

Cerebrum-the cortex

Answer 28

• Cortex divided into a number of functional areas – –motor –sensory –association –integrative

Question 29

Sensory cortex

Answer 29

• Mainly the posterior half of both cerebral hemispheres, association areas adjacent to these regions • Primary Somatosensory Area (Area 1,2,3) -located directly posterior to the central sulcus • Primary visual area (Area 17) -posterior tip of occipital lobe • Primary Auditory Area (Area 41, 42) –superior part of temporal lobe

Question 30

Association areas

Answer 30

Interpret incoming information (or coordinate motor responses) • Somatosensory Association Area (5,7) integrates and interprets sensations e.g. determining shape and texture • Visual Association Area (18,19) • Premotor Area (6)

Question 31

Integrative centres

Answer 31

Integrative Centres • Coordinate information from a number of association areas (and direct complex movements) • Also undertake complicated analytical functions e.g. abstract thought • –Generalinterpretivearea–Wernickesarea • –integrates sensory info and oversees access to visual and auditory memories • –damage limits the ability to interpret what is seen or heard

Question 32

Motor Activity

Answer 32

• Electrical stimulation of areas of the cortex resulted in movements of specific contralateral areas • How we generate voluntary movement not clearly understood –But possible to record electrical activity in the pre-motor cortex, almost a second before movement = readiness potential