Hubs191

Front 1

what is the central nervous system (CNS) composed of?

Back 1

has brain, spinal cord ( which are composed of neutrons and gila)

Front 2

what is the peripheral nervous system composed of?

Back 2

peripheral nerves and ganglia ( composed of neurones and gila)

Front 3

what are neurons and gila?

Back 3

neurones- specialazied trasmission cells

gila-support neurones

Front 4

give the structure of a Neuron

Back 4

Front 5

describe the input zone, summation zone, conduction zone and the output zone

Back 5

the input zone ( dendrites and cell bod) receives chemical signals from other neurones, the summation zone has the axon hillock and carries summation of inputs, the conduction zone (axon) carries electrical signals between brain areas and spinal cord. the output zone has contact with the input zone of other neurones and effectors. releases neurotransmitters , which is a chemical signal

Front 6

name the 4 types of neurons?

Back 6

multipolar, bipolar, unipolar, anaxonic

Front 7

what are the 5 types of gila cells and there location?

Back 7

astrocytes (CNS)

microglia (CNS)

ependymal (CNS)

oligodendrocytes (CNS)

Schwann cells (PNS)

Front 8

what is the purpose of the myelin sheath?

Back 8

the myelin sheath is multiple Schwann cells in line, nodes of ranvier are gaps between myelin. this purpose is to increase conduction velocity.

Front 9

what is the structure of a synapse?

Back 9

a synapse is the release of neurotransmitters from the axon terminal of the presynaptic neurones to the input zone of the post synaptic neuron.

Front 10

describe the electrical nerve impulse at the synapse

Back 10

the action potential is an electrical signal going down the axon of the presynaptic neuron. it is then turned into a chemical signal during the synapse. Then back into an electrical signal

Front 11

what are the directions of information flow into and out of the nervous system

Back 11

information into the brain is afferent, information out of the brain is efferent.

Front 12

what is the somatic division of the nervous system

Back 12

somatic efferent is voluntary muscle control and somatic afferent is sensory information were aware of (somatic what we are aware of)

Front 13

what is the autonomic division of the nervous system?

Back 13

autonomic efferent is involuntary muscle control, autonomic afferent is sensory information we are not aware of.

Autonomic ( not aware of)

Front 14

what is the anatomical organisation of the somatic efferent division of the nervous system?

Back 14

somatic efferent- two neurones between brain and effector

1. upper motor neuron ( cell body in brain, axon in spinal cord)

2. lower motor neuron ( cell body in spinal cord axon in spinal nerve)

Axons are myelinated and the neurotransmitters is acetylcholine (Ach)

Front 15

how do neurones communicate with effector cells in the somatic efferent division?

Back 15

the lower motor neuron synapses on effector, eg skeletal muscle.

Front 16

what are the anatomical organisation of the autonomic nervous system?

Back 16

sympathetic and parasympathetic, the effectors are smooth and cardiac muscle, glands and adipose tissue.

Front 17

what is the neural organisation in autonomic nervous system?

Back 17

neuron1- cell body in brain, axon in brain or spinal cord

neruon2- cell body in brain or spinal cord (CNS), axon in PNS

neuron3-cell body and axons in PNS

Front 18

how does the autonomic neurons communicate with effector cells?

Back 18

neuron 2 is the pre-ganglionic neuron it is myelinated and synapse in autonomic ganglion, neurotransmitter (Ach)

neuron 3 is the post ganglionic neuron, it is unmyelinated the synapse on effector organ, neurotransmitter is Ach or norepinephrine.

Front 19

what are key features of the sympathetic nervous system?

Back 19

prepares the body for acute/ stress response. ( fight or flight) the effects include

-increased heart rate, constricting blood vessels, increased blood flow to muscles, decreases gastric motility, decreased salivation, increased pupils size increased sweating.

Front 20

what are key feature of the parasympathetic nervous system?

Back 20

prepress body for rest, rest and digest

effects include

decreased heart rate, increased gastric motility, decreased pupil size, increased salivation.

Front 21

what is an action potential?

Back 21

an action poetical is the basis of neural communication, they are electrical impulses passing along axons.

Front 22

d

Back 22

d

Front 23

discuss the key features of membrane potential?

Back 23

intercellular cation(K), extracellular(Na) which are separated by phospholipid bilayer. can only move via channels and only potassium has constantly open channels. chemical gradient forces potassium out, electrical gradient forces potassium in. RMP -70mv

Front 24

what is graded potential

Back 24

this is the change in neural membrane potential but not necessarily enough to induce an action potential. can be excitatory- depolarise the membrane (more positive) or can be inhibitory hyper polarise the membrane (more negative)

Front 25

what is threshold potential?

Back 25

a membrane potential where an action potential can now occur, if the threshold potential is not reached there is no action potential. at -40mv voltage gated sodium channels open causing massive Na+ influx and depolarisation

Front 26

what is an action potential?

Back 26

information sent down an axon that is actively generating electrical impulses.

Front 27

what is a voltage gated ion channel?

Back 27

voltage gated ion channels are across the neurones and axon. there are sodium and potassium ion channels. they repolarise and depolarise action potentials.

Front 28

what is AP propagation?

Back 28

when voltage gated ion channels open at the axon initial segment.

Front 29

describe the timing of events the underlie the action potential?

Back 29

once threshold potential is released (-60mv), VGSC open causing massive Na+ influx and depolarisation. VGSC close at -30mv, VGPC open casting potassium efflux and repolarisation of the cell. once potential reaches -70mv again VGPC close. resting membrane potential is restored via Na/K+ atlases pumps until next action potential occurs

Front 30

what is a refractory period of an axon?

Back 30

periods of action potential where receptors cannot be reactivated

Front 31

what is absolute refractory period?

Back 31

receptors are 100% inactive no new can be created

Front 32

what is relative refractory period?

Back 32

receptors require larger stimulus to create same potential father away from threshold.

Front 33

how can the speed of an action potential be enhanced?

Back 33

myelinated and unmyelinated have different ways of propagation. ( conducting an action potential). myelinated is faster, action potentials jump from node to node and are restored at each node, only has sodium channels. unmyelinated is slower

Front 34

what is chemical synaptic transmission?

Back 34

at rest Ach channels are closed, as Ach is realeased from a terminal, it binds to a sub unit. this causes a change in charge and change in strucuture of the protein. so the pore becomes available for ion entry.

once Ach has done its job it is removed from the binding site. the channels close until the next action potential.

Front 35

what are regulatory neurons?

Back 35

they regulate the property of the nerve terminal, this influences its responsiveness to action potentials. coming out of the axon.

Front 36

what is a presynaptic nerve and a postsynaptic nerve?

Back 36

gives synaptic output ( pre synapse), receives synaptic output (post synapse)

Front 37

what are the critical components of a chemical synapse?

Back 37

mitochondria- energy intensive process. eg calcium needs to be recycled and the concentration has to be regulated. Ach sterase a mechanism that destroys Ach to make sure that there is a post synaptic response for every pre synaptic Ach. chemically gated receptor for Ach on the post synaptic neuron or muscle-ACh bins opening chemical channel for ion transport. Ca- enters presynaptic terminal by VG Ca channels. that open for action potentials. A current comes down the axon. this is strong enough to open the channels. vesicles fuse with the post synaptic membrane and release their contents into synaptic cleft.

Front 38

explanation the steps of chemical synaptic transmission

Back 38

action potentials open voltage gated calcium channels, calcium ion diffuse into the axon terminal and trigger synaptic vesicles to release Ach by exocytosis. Ach diffuse across synaptic cleft, and binds to Ach Na ion channels.

Front 39

where does the spinal cord start and Finnish?

Back 39

starts at Foramen magnum, big hole at base of th e skull, it ends at L1 , first lumbar vertebra.

Front 40

what is the spinal cord?

Back 40

it is a sac made of meninges, that fits into spinal cavity. spinal cavity within vertebra

Front 41

white matter

Back 41

axons

Front 42

grey matter

Back 42

cell bodies

Front 43

median sulcus

Back 43

back of spinal cord

Front 44

central canal

Back 44

Hole in middle

Front 45

median fissure

Back 45

front of spinal cord

Front 46

dorsal horn, lateral horn, ventral horn are all

Back 46

cell Bodies

Front 47

dorsal, lateral and ventral column are all

Back 47

axons

Front 48

dorsal root ganglion

Back 48

cell bodies

Front 49

dorsal nerve root

Back 49

axons

Front 50

ventral nerve root

Back 50

axons

Front 51

how does afferent information flow into the spinal cord?

Back 51

afferent inforamtion flows from dorsal root ganglion to dorsal nerve root into spinal cord, from PNS to CNS

Front 52

how does efferent information flow within the spinal cord?

Back 52

information flows from CNS to PNS and exists through ventral nerve root.

Front 53

The dorsal nerve root only..

Back 53

carries afferent information

Front 54

the ventral nerve root only..

Back 54

carries efferent information

Front 55

spinal nerves carry

Back 55

both efferent and afferent.

Front 56

dorsal ramus

Back 56

efferent to back, afferent from back

Front 57

ventral ramus

Back 57

efferent to ventral body, afferent form ventral body

Front 58

rami communions

Back 58

sympathetic only at T1-L2

Front 59

what are the 3 meninges covering the brain

Back 59

dura mater, arachnoid, and pia mater

Front 60

venous sinuses

Back 60

space between layers of Meninges

Front 61

what are dura folds

Back 61

separates major sections of the brain and provides stability.

Front 62

what is the flax cerebella dura fold

Back 62

separates cerebral hemisphere ( median plane)

Front 63

where is the tentorium cerebella dura fold

Back 63

separates cerebrum from cerebellum ( horizontal plane)

Front 64

what is venous sinus

Back 64

where two layers of dura matter separate collects veins. getting venous blood from brain and old CSF.

Front 65

what are features of dura mater

Back 65

dense and fibrous, two layers inner and outer

Front 66

what are features of arachnoid mater?

Back 66

subarachnoid space ( contains blood vessels) and arachnoid granulations

Front 67

describe the subarachnoid space?

Back 67

filled with CSF between arachnoid and Pia mater.

Front 68

what are arachnoid granulations?

Back 68

perforate inner layer of dura matter, transport old CSF from subarachnoid space into venous sinus.

Front 69

what are the key features of Pia matter?

Back 69

transparent and delicate, blood vessels in arachnoid sit on top of Pia mater, adheres to brain and follows gyro and extends into sulci.

Front 70

what is the ventricular system?

Back 70

Network of interconnected spaces within the brain. filled with CSF this nourishes and protects the brain. spaces lined with ependymal cells( this circulate CSF)

Front 71

where are the two lateral ventricles?

Back 71

one in each cerebral hemisphere

Front 72

where is the third ventricle

Back 72

located in diencephalon

Front 73

where is the cerebral aqueduct

Back 73

connects 3rd and 4th ventricle. located in mid brain

Front 74

where is the fourth ventricle?

Back 74

located at level of cerebellum

Front 75

what is the purpose of CSF?

Back 75

provides support and cushion, transports nutrients and waste. it is produced by choroid plexus within the ventricles

Front 76

describe the circulation path of CSF?

Back 76

starts at lateral ventricles, 3rd ventricles, cerebral aqueduct, 4th ventricle, subarachnoid space.

subarachnoid space flows it around the brain and spinal cord it then exits through arachnoid granulations into venous sinus

Front 77

corpus callosum

Back 77

white matter in brain ( axons that cross from side to side)

Front 78

projection tracts

Back 78

axons extend between cortes and other CNS areas outside cerebrum ( white matter)

Front 79

association tracts

Back 79

axons on same side within cerebral cortex, communication between brain areas

Front 80

what is the anatomy for the main motor pathway for voluntary movement?

Back 80

two neurons between brain and effectors,

upper; cell body in primary cortex( precentral gyrus) axon extends from motor cortex to spinal cord on opposite side. makes a synapse on lower motor neuron

lower; cell body in ventral horn of spinal cord, axon extends out of spinal cord (central root) into body. makes synapse on skeletal muscle.

Front 81

what is the anatomy of somatosensory pathway?

Back 81

3 neurons between sensory receptor and somatosensory neurone in post central gyrus

Front 82

what are reflex and voluntary movements?

Back 82

reflex is an involuntary response to a particular sensory stimuli and voluntary movements are made with the intention to act.

Front 83

what is a stretch reflex?

Back 83

the stimulation of receptor by a stimuli, leads to activation of a sensory neuron, causing information processing in the CNS, activation of a motor neurone and finally a response of a peripheral effector.

Front 84

how does a ,muscle spindle relate to a stretch reflex ?

Back 84

a stretch reflex leads to a shortening of muscle, also has effects on posture.

Front 85

discuss muscle spindle fibres?

Back 85

they have sensory index wrapped around them, so when they are stretched, the ion channels open causing depolarisation, the muscle fibres also keep a steady tension on muscle spindle fibres. so conduction is easily sensed.

Front 86

discuss the withdrawal reflex?

Back 86

painful stimuli activates posterior root ganglion, distribution within Gray-horn to other segments of the spinal cord and brain, flexors stimulated and extensors inhibited. inhibitory actions are not autonomic we are aware of them.

Front 87

describe the primary motor cortex?

Back 87

the primary motor cortex Is distorted, this means large areas of the motor cortex control particular muscle. ( thumb and tongue) while other body parts are controlled by small regions( wrist)

Front 88

the primary motor cortex is determined by

Back 88

how many muscle fibres a single neuron controls( how much fine motor control the particular effector needs.

thumb needs larger region of motor control as the motor units are small and need more stimulation.

Front 89

what are major steps in voluntary control of movement?

Back 89

the prefrontal cortex, basal nuclei and cerebellum provides information on the surroundings and current body position to the premotor cortex in the precentral gyrus. - axons of the primary motor cortex, project to the spinal cord, and travel to skeletal muscle via peripheral nerves.- cerebellum then compares sensory feedback about the actual movement to intended movement and signals adjustments to the primary motor cortex

Front 90

caused for voluntary movement?

Back 90

internally generated movement; movements that arise from activity in many brain regions (prefrontal ,medial premotor, cerebral cortical)

externally cued movement; in response to specific external cues, triggered by sensory information arriving from sensory pathways.

Front 91

describe the role of the cerebellum in voluntary movement?

Back 91

cerebellums function is to prepare for movement, preform movement and maintain posture.

compute movements needed to achieve new body position (feed forward) , coordinates muscles guided by sensory ( feedback) , compares intended movement with actual result, helps maintain posture and gaze- monitors balance/ equilibrium., helps learn and automate movements, adjusts upper neuron activity.

Front 92

define somatic sensation and special senses?

Back 92

somatic sensations and special sensations are types of input into the CNS

Front 93

what are special senses?

Back 93

require a specialised sensory cell and a specialised organ for transduction ( vision, hearing, taste, smell, vesticular (balance)

Front 94

what are somatic sensations

Back 94

axons carry out transduction( touch, pain , warm cold , body position.)

Front 95

what what is direct and endocrine?

Back 95

direct- temperature sensing (maintain core temp)

endocrine - food intake and regulation.

Front 96

swhat are sensory receptors?

Back 96

sensory ending of an afferent neuron ( somatosensory) or specialised receptor cell, highly sensitive to a particular stimulus.

Front 97

what are examples of stimulus encoded by sensory systems?

Back 97

modality, intensity, duration, location

Front 98

what is modality?

Back 98

a type of sensory receptor activated,

proprioception; type of receptor present to receive input.

touch; axons are wound around the base of hair, which detects motion and pressure.

Front 99

what is intensity?

Back 99

the frequency of action potential firing in afferent neuron. the stronger the input the more likely an action potential will arise at the first node- therefore the more action potentials that will arise.

stronger stimuli can also activate more receptors and action potentials in more sensory axons.

Front 100

what is duration?

Back 100

how long action potentials firing afferent neurons. can be sensitive to change, often show adaption- decreased output over time in response to continuous stimulation.

Front 101

what is location

Back 101

where the sensory receptors are activated

( mapped in the brain)

- where they are on somatotopic map ,

receptive fields is a space which stimuli can lead activity in a particular afferent neurones. these regions overlap, so the stronger the stimuli it may activate more than one receptive field.

Front 102

conscious sensations are

Back 102

intergration, cerebral cortex, conscious sensation and perception.

afferent neurons, peripheral nerve, tract or pathway