Module 2

Question 1

frontal lobe

Answer 1

executive functioning - planning, thinking, problem solving, organising, memory, emotional regulation, personality and behavioural control.

inludes the primary motor cortex which initiates movement.

Question 2

parietal lobe

Answer 2

arithmetic and spelling, interpreting surroundings, perception.

includes sensory cortex which is responsible for processing sensations.

Question 3

occipital lobe

Answer 3

processes vision

includes primary visual cortex.

Question 4

temporal lobe

Answer 4

memory, language comprehension.

Question 5

what is the structure of the cerebral cortex

Answer 5

is a blanket layer of cells covering the cerebral hemispheres.

grey matter 2-5mm thick.

2 major regions - neocortex has 6 layers and makes up 90 percent of cortex.

allocortex has less than 6 layers of cells and has the allofactory cortex (smell).

Question 6

what are the major cells in the CNS

Answer 6

neurons - excitable cells that are able to transmit nervous messages.

neuroglia - specialized cells that are found only in close association with neurons, they are supporting cells that provide nutrition to neurons, help remove waste and do not directly participate in information transfer.

Question 7

types of neurons

Answer 7

multipolar - classic structure of neuron, carries impulses from CNS to effectors.

bipolar - cell body is between two axons, trigger zone right after soma closer to terminals, sesnory neuron in eye and ear. the bipolar neuron lies between sensory and motor neurons and shuttle signals through CNS pathways.

pseudo/unipolar = soma sticks out of middle of axon, trigger zone is right after dendrites, sensory neuron, transmits signals towards CNS.

Question 8

what are the four types of cells in the CNS

Answer 8

oliodendrocytes
astrocytes
microglia
ependymal cells

Question 9

what are the two types of cells in the PNS

Answer 9

schwann cells

satellite cells

Question 10

which cells produce myelin in the CNS and PNS

Answer 10

oliodendrocytes (CNS) - one oligo myelinates 60 axons.

schwann cells - 1 cell + 1 axons.

Question 11

what is the function of myelin

Answer 11

1. increase transmission speed
2. protect and insulate axons
3. functions to also repair axons.

Question 12

what are astrocytes

Answer 12

most abundant type of glia:

star shaped, wrap around capillaries, provides nutrients, homeostasis, regulation synaptic connections, reactions to injuries.

Question 13

what do satellite cells function as

Answer 13

satellite cells are glia cells that perform the same function as astrocytes but in the PNS rather than the CNS.

Question 14

describe resting potential

Answer 14

higher concentration of potassium inside the cell membrane, and a lower concentration of sodium outside, chlorine is also higher outside the cell.

anions are higher inside the cell (large proteins)

voltage = -70mV.

Question 15

what are ligand gated channels and voltage gated channels

Answer 15

ligand gated - open and closes either spontaneously or in response to a chemical stimulus, such as the binding of a molecule to the channel protein (Acetylcholine).

voltage gated channels - open and closes spontaneously or in response to a change of voltage across the membrane that is sensed by the changed segments of the channel protein.

Question 16

what does resting potential depend on

Answer 16

permeability - anions such as proteins cant go through therefore greater negative charge on the inside of the cell because they live inside the cell.

electrochemical gradients - charge and concentration of ions. the electrochemical gradient from inside to outside goes from negative to positive.

Question 17

how does a sodium potassium pump function neurotransmission

Answer 17

returns the sodium and potassium ions that leak through the membrane.

uses ATP - active transport, moves the ions against the electrochemical gradient, helps maintain RMP.

contributes to 5-20mV to RMP.

Question 18

what is the action potential process

Answer 18

Action potential process

Depolarisation to threshold – stimulus provokes the membrane to reach –55mV.

Activation of Na+ channels – Na+ channel gates open which allows an influx of Na+ ions into the cell, causing the membrane potential to reach +30mV.

Inactivation of Na+ channels and activation of K+ channels.

Repolarisation - K+ channels still open – positive charge will leave the neuron causing the membrane potential to become more negative.

Hyperpolarisation – potassium channel takes longer to close so the overall membrane potential will decrease to –90mV as more positive K+ are going out.

Return to normal permeability - K+ channels closed, leak channels return K+ back into cell to go back to –70mV.

Question 19

what is the absolute refractory period and relative refractory period

Answer 19

absolute - sodium channels open or inactivated. no action potential possible.

relative - membrane potential is almost normal only a very large stimulus can initiate an action potential.

Question 20

is continuous or saltatory propagation faster

Answer 20

saltatory propagation is faster because AP’s propagate along the length of the axon by jumping from node to node rather than diffusing through channels over and over like in continuous.

Question 21

what is the effect of fibre diametre on AP conduction

Answer 21

as fibre size increases - conduction velocity of AP’s increase.

CV is increased by myelination.

Question 22

what are the two types of synapses

Answer 22

electrical - gap junction (bidirectional)

chemical - axoaxonic (between two axons), axosomatic (between soma and axon), axodendritic (between axon and dendrites - most common).

examples of synpase locations are neuron to neuron, neuromuscular and neuroglandular.

Question 23

how can neurotransmitters be broken down - process of inactivation

Answer 23

1. may be broken down by specific enzymes in synaptic cleft.
2. may be reuptaken at pre-synaptic button by specific transporter.
3. diffuse away.

Question 24

what are the main neurotransmitters

Answer 24

acetylcholine
glutamate
GABA
catecholamines

Question 25

acetylcholine

Answer 25

CNS - widely spread
PNS - is at neuromuscular junctions and autonomic nervous system.

involved in memory, muscle control, autonomic control.

acts on cholinergic receptors:

1. muscarinic receptors - metabotropic receptors, activate molecules inside the cell to cause function by phosphorylation.
2. nicotinic receptors - ionotropic (ligand gated channels).

Question 26

glutamate

Answer 26

major excitatory neurotransmitter in brain.

in CNS - brainstem, role in learning and memory.

acts on both metabotropic and channel receptors.

Question 27

GABA

Answer 27

major inhibitory in brain

cerebral cortex, spinal cord, interneurons throughout the brain, cerebellum.

depressant effects - makes cell more negative, hyperpolarisation.

GABA receptors are channel receptors for Cl- ions.

Question 28

catecholamines

Answer 28

norepinephrine - alertness, reward, motivation.

serotonin - memory, happiness, obsessions and compulsions.

dopamine - pleasure, reward, motivation, lack of = parkinsions disease.

Question 29

brainstem

Answer 29

located between spinal cord and medulla oblongata

ascending and descending pathways.

mediates complex primitive behaviors such as swallowing, breathing, heartrate, blood pressure.

Question 30

cerebellum

Answer 30

rapid coordination of movement, automatic adjustments to maintain balance and posture.

major role in motor learning of a new skill, involved in detecting an error and eliminating error from a mastered skill.

slightly role in personality

Question 31

subcortical regions

Answer 31

diencephalon - hypothalamus and thalamus

midbrain

pons

medulla oblongata

Question 32

hypothalamus and thalamus

Answer 32

hypothalamus - highest center for autonomic control - HR, BP, digestion, thermoregulation.

thalamus - relay and processing centers for sensory info.

Question 33

pons

Answer 33

relays sensory info to cerebellum and thalamus, subconscious somatic and visceral motor centers.

Question 34

medulla oblongata

Answer 34

relays sensory info to thalamus and other parts of brainstem, autonomic centers for regulation of visceral function (cardiovascular, respiratory, digestive system).

Question 35

midbrain

Answer 35

processing of visual and auditory date, generation of reflexive somatic motor. maintenance of consciousness.

Question 36

what do association areas do

and primary cortical areas

Answer 36

integrate and process info from relevant senses, helps with understanding.

Primary cortical areas – simplest level of processing (e.g. - can identify where you feel a sensation but no interpretation).

Association cortex – produce perception, interpret by comparing current experience to memory, produce more complex, bimanual, planned motor activity.

Question 37

what are the motor areas of the cerebrum

Answer 37

Motor areas of cerebrum:

Primary motor cortex – site which gives rise to motor output (muscle contraction) - no planning, just delivery.

Premotor area – sends a program of movement or muscles recruitments, motor activities in response to visual or sensory cues, role in controlling the postural parts of movement (e.g. stabilising shoulders with object in the hand).

Supplementary motor area – sends to the primary motor cortex, planning and pre-programming of movement sequences.

Basal ganglia – group of nuclei located deep in the cerebral hemisphere

Caudate nucleus, putamen, globus, pallidus subthalamic nucleus, substania nigra (in midbrain).

Important role in planning and executing fine voluntary movements.

Has its effect by influencing motor cortical output.

Role in cognition and attention.

Works with supplementary motor area.

Question 38

what are meniges and their functions

Answer 38

Meninges: layers of corpus callosum

Three main functions:

Protect the underlying brain and spinal cord.

Serve as a support framework for important arteries and veins and sinuses.

Enclose the subarachnoid space (with CFS)

Question 39

cerebrospinal fluid

Answer 39

Cerebrospinal fluid

Has 3 functions:

Cushions delicate neural structure

Supports brain (oxygen and nutrients).

Transports chemical messengers and waste products (maintains homeostasis).

Is produced by the choroid plexi at the base of the third and fourth ventricles.

Question 40

spinal cord

Answer 40

Spinal cord

Major column of nerve tissue (millions of neurons and neuroglia) lying within the vertebral canal and from which the spinal nerves emerge.

Extends from the foremen magnum to lumbar vertebral column, ends level with the L1-L2 disc.

Question 41

what are the spinal cord segments

Answer 41

the spinal cord is divided to segments

Cervical nerves – 8 pairs

Thoracic nerves – 12 pairs

Lumbar nerves – 5 pairs

Sacral nerves – 5 pairs

Coccygeal nerves – 1 pair.

Question 42

describe the structure of spinal cord segments

Answer 42

Spinal cord segment

from each segment of the spinal cord there are groups of dorsal and ventral rootlets, which then combine to form the spinal nerve at each level.

Grey matter = contains nerve cell bodies, dendrites, unmyelinated axons and neuroglia. The absence of myelin accounts for their grey colour.

Grey matter is arranged in horns – which describes their shape.

There is posterior (dorsal) horn which deals with sensory info

There is anterior (ventral) horn which deals with motor info.

There is a lateral horn which deals with autonomic info.

White matter = aggregations of myelinated axons from many neurons supported by neuroglia. Myelin is a whitish colour which accounts for the colour.

White matter is arranged in columns, bundles of axons on the outside of the horns going up and down the spinal cord.

Question 43

ascending and descending pathways

Answer 43

Sensory pathways (afferent pathways) sends info up to the brain to be processed via DORSAL ROOT of spinal cord. - ascending – includes spinothalamic tract which is a long bundle of nerve fibres (myelinated neurons so white matter) which is a soma-sensory tract).

Spinothalamic tract: afferent pathway transmitting pain, temperature, itching, tickling, deep pressure, crude touch.

It travels from sensory receptors to the spinal cord and up to the primary somato-sensory cortex.

Ascending fibres differ in size and myelination status according to the carried sensory info.

4 different types – A-alpha, A-beta, A-delta and C – in order from biggest to smallest. Bigger = faster.

Motor pathways (efferent pathways) sends signals down to muscles and organs via VENTRAL ROOT of spinal cord. - descending – corticospinal tract which a bundle of nerve fibres concerned with motor movements.

Corticospinal tract: originates in the primary motor cortex, which generates neural impulses controlling execution of movement after receiving info from associative motor area and premotor area.

Controls voluntary movement.

Motor homunculus.

Question 44

ganglion , pre and post

Answer 44

The preganglionic neuron – has its soma within the brain or spinal cord while the preganglionic fibre (the myelinated axon) passes out of the CNS as part of a cranial or spinal nerve. At some point the fibre separates from the nerve and courses to an autonomic ganglion.

The autonomic ganglion, contains the axon terminals of the preganglionic fibre and the soma and dendrites of the postganglionic neuron.

The post ganglionic fibre lies outside the ganglion and is unmyelinated.

Question 45

what is the neural pathway of the autonomic response

Answer 45

Neural pathway of autonomic response:

Visceral sensory neuron -> sensory horn of spinal cord (dorsal/posterior) -> integration in CNS (higher centre or spinal cord) -> lateral horn of spinal cord (preganglionic neuron) -> synapse with post ganglionic neuron in ganglion (sympathetic trunk) -> effectors

Question 46

what neurotransmitter do preganglionic neurons release

Answer 46

Acetylcholine

Question 47

what neurotransmitters do postganglionic neurons release

Answer 47

acetylcholine and norepinephrine.

Question 48

developmental aspects of the ANS

Answer 48

Developmental aspects of ANS:

In elderly people, ANS efficiency declines.

Constipation

Orthostatic hypotension – low blood pressure during changes in body position.

This is because the ANS is in control of digestive system……parasympathetic

Sympathetic nervous system – can control diameter of blood vessels.

Question 49

age related changes in the nervous system include:

Answer 49

Development of the nervous systems is characterised by 3 phases:

Neurogenesis, neural proliferation and migration, folding

Neurulation starts week 3 of gestation (neural progenitor cells divide and migrate)

Neural plate – neural groove – neural tube – primary brain vesicles – secondary brain vesicles. - thickens each time.

Neuronal connectivity and myelination

Around week 12 – gradual thickening of the cortex and formation of cortical layers.

Around mid-gestation – direct contact between cortex and rest of CNS. Gyrification and first primary sulci form.

Synaptogenesis and synaptic pruning.

Commences from the end of the third month: myelination of peripheral sensory nerve then spinal cord.

Brain structures myelination starts around 6 month of gestation, continues through childhood.

Motor fibres do not begin to myelinate until after birth and continue to for the two years at least.

Question 50

what are the changes in the NS in adolescence and early adulthood.

Answer 50

Changes in NS in adolescence and early adulthood:

Ongoing myelination of the brain, plus thinning of grey matter associated with synaptic pruning.

Oestrogen and testosterone play a role in promoting nervous system growth in adolescence and pruning.

Brain increases in size by 4-fold since birth, reaching approximately adult volume by 18-20 years old.

The hippocampus

Role = encoding

New neurons formed in the hippocampus throughout life but rate is inversely proportional to age. However can be maintained by purposeful learning.

Question 51

what are the changes in the NS in ageing:

Answer 51

Changes in NS in ageing:

Deterioration with age – this is normal healthy ageing and does not include diseases known to be more prevalent in ageing populations (dementia).

Brain weight decline – by 80 years brain has declined in weight by 15%.

Reduced biochemical activity – reduced ion channels, reduced number of receptors, reduced levels of neurotransmitters.

Signs of ageing associated with NS changes:

Altered sleep patterns

Changes in mood

Apathy

Loss of appetite, constipation

Loss of memory

Reduced motor control

Impaired sensation and perception

Weakened loss of reflexes.

Question 52

define areflexia, hyporeflexia, and hypereflexia.

Answer 52

Absence of reflexes – areflexia

Increased or overactive – hyperreflexia

Decreased reflexes – hyporeflexia

Question 53

how are reflexes classified

Answer 53

Reflexes can be classified by:

By development

Innate reflexes – genetically or developmentally determined.

Basic neural reflexes, formed before birth, can disappear with age or still be maintain if useful.

Acquired reflexes – learned.

Rapid, autonomic, learned motor patterns.

By response

Visceral (autonomic) reflexes – control actions of smooth and cardiac muscles and glands.

Somatic reflexes – control skeletal muscle contractions , include superficial and stretch reflexes.

Superficial – skin, mucous, membranes.

Stretch or deep tendons reflexes – patellar reflex.

By complexity of circuit

Monosynaptic – one synapse – shorter time.

Polysynaptic – two or more synapses. - longer reflex delay.

By processing site

Spinal reflexes – processing in spinal cord

e.g. Patellar reflex.

Can be complex – involving several segments in spinal cord.

Cranial reflexes – processing in brain.

e.g. bright light in eye – eye constricts, consensual response.

Question 54

what are the 5 components of a reflex arc

Answer 54

Five components of a reflex arc:

Sensory receptor – responds to a stimulus by producing a generator or receptor potential.

Sensory neuron – axon conducts impulses from receptor to integrating centre.

Integration centre – one or more regions within the CNS that relay impulses from sensory to motor neurons.

Motor neuron – axon conducts impulses from integrating entre to effector.

Effector – muscle of gland that responds to motor nerve impulses.

Question 55

what is the sympathetic and parasympathetic tone

Answer 55

Sympathetic tone – vasomotor tone (diameter of blood vessels)

Sympathetic division controls blood pressure, even at rest.

Keeps the blood vessel in a continual state of partial constriction.

Sympathetic fibres fire more rapidly to constrict blood vessels to rise.

Sympathetic fibres fire less rapidly to prompt vessels to dilate to decrease blood pressure.

drugs that block sympathetic tone are used to treat hypertension.

Parasympathetic tone

Parasympathetic division normally dominates the heart and smooth muscle of digestive system and urinary tract.

Slows heart (via vagus nerve)

Dictates normal activity levels of digestive and urinary tracts.

Sympathetic division can override these effects during times of stress.