Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neuro - Lecture 1 - Physiology Of Motor Control > Subdivisions Of The Nervous System > Flashcards

Subdivisions Of The Nervous System Flashcards

1
Q

Afferent Neurones

A
  • Sensory
  • Afferent info travels toward the brain (ascending)
  • Fibres found in dorsal region of the spinal cord
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Efferent Neurones

A
  • Motor neurones
  • Efferent in for travels away from the brain (to effector)
  • Fibres found in the ventral region of the Spinal cord
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Peripheral Nervous System (PNS)

A

Consists of autonomic & somatic NS (peripheral nerves)

PNS do regenerate after injury

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Central Nervous System (CNS)

A

Consists of brain and spinal cord [acts as a single entity], most learned responses occur in SC.

CNS nerves don’t regenerate following injury, instead they undergo Wallerian degeneration & die. [swelling, lack of blood flow kills Neurones]

[but hippocampus - memory area/ learning centre - regeneration found in 2013]
Olfactory can also regenerate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

PNS - Peripheral Nerves + Glia:

A

Peripheral nerves:
A fibres [fast myelinated]
C fibres [ slow unmyelinated]- normally associated with pain response
Muscle spindle afferents [Ia & II]
Golgi tendon organs [Ib]
Alpha & gamma motor fibres - Alpha = goes straight to skeletal muscle, voluntary control. Gamma = actives muscles spindles subconsciously.

Glia:
Schwann cells [myelinated peripheral nerve axons]
Satellite cells [regulate chemical environment] - stem cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

CNS - Neurones + Glia

A

Neurones:

Pyramidal cells [cortex] - motor control and movement
Beth cells [ motor cortex]
Purkinje cells [ cerebellum]
Motor neurones [spinal cord] - starts in SC goes to muscles

Glia [Glue]:

Oligodendrocytes [myelinate neuronal axons] - same as Schwann Cells.
Astro Yates [matirix/scaffolding] - star look alike, neural support and repairs damage, helps prevent major inflammation
Microglia [may ingest microbes and broken down tissues]
Radial glia - neurogenesis
Ependymal cells [secretes cerebrospinal fluid/circulate CSF with cilia]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Neurones - the basic unit of CNS

A

Oligodendrocytes in CNS and Schwann cells in the PNS are the glial cells responsible for myelinating the axons of neurones.

Myelin acts as insulation allowing rapid propagation of neural impulses along axon.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Neurones - The Action Potential

A

Electrochemical potential exists across the membrane of neurone as ion concentrations inside the cell aren’t the same as outside the cell

When a neurone is stimulated Na channels open & Na ions enter the cell along their electrochemical gradient

This changes the voltage across the membrane [becomes less -ve]

Voltage sensitive Na channels open allowing more Na to rapidly enter the cell and further depolarise it

~15mV change in membrane potential pushes neurone beyond ‘threshold’ and action potential ensues.

Resting membrane potential = ~70mV
Threshold = ~55mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Sensing - Peripheral receptors

Muscles spindles

A

MS = muscle fibre with sensory organ wrapped around it.

MS are constantly firing to sense where joints are.

Golgi tendon smooths the forces as more motor units are recruited

Pressure and pain receptors are - inhibitory receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Muscle spindle receptors

A

Mechanoreceptors [stretch sensitive]

Important for proprioceptive feedback

Involved in spinal reflec circuitry

Coil around intrafusal muscles fibres

Detect absolute length & changes in muscle length

Are located at the end of Ia and II afferent fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Golgi tendon organs

A

Mechanoreceptors [stretch-sensitive]

Detect muscle tension

Located at muscle-tendon junction

Modulates muscle output in response to fatigue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Joint receptors

A

Mechanoreceptors [stretch-sensitive]

Location at junction capsule

Only respond to limited range of overlapping angles

Higher level of CNS determines joint position & perception of our position in space by monitoring which receptors are activated at the same time

Some are sensitive to extreme joint angle i.e. Provide danger signal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Cutaneous receptors

A

Mechanoreceptors e.g. Pacinian corpuscles detect mechanical stimuli on skin.

Thermoreceptors detect temperature changes.

Notice-toes detect potential damage to skin [pain].

Afferent info goes to the thalamus first, then to cerebellum - it needs a lot of info in order to do a proper comparison

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Sensing - The Afferent types

A

Ia - muscles spindles [stretch reflex]
Ib- Golgi tendon organ [inhibitory reflex]
= senses velocity and length change.

II - muscle spindles [stretch reflex]
III - mechanical stimuli e.g. Pressure
= only detects length change.

IV - chemical stimuli e.g. Pain, temperature.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Sensing - Ascending Pathways

  1. Dorsal column - medial lemniscal system
A

Dorsal column - medial lemniscal system

Info on touch, pressure and proprioception

Fasciculus Cuneate pathway- Lateral tract - for upper limb.

Fasciculus Gracillis pathway - Medial tract - for lower limb.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Sensing - Ascending Pathways

  1. Anterolateral system - Spinothalamic tract
A

Anterolateral system - Spinothalamic tract

Info on pain, temp and crude touch.

This tract crosses over immediately where it enters the SC and runs more anterolateral than dorsal.

17
Q

Sensing - Ascending Pathways

Spinocerebellar Pathway

A

Spinocerebellar Pathway

18
Q

Sensory Info - Passes through the Thalamus

A

All sensory info passes through the thalamus before reaching the cortex - except smell - process sensory info

The Thalamus also receives info from the cortex [prefrontal, motor, visual cornices, etc], basal ganglia and cerebellum.

19
Q

Other important centres in the brain:

A

The Hippocampus - the learning centre

The Amygdala - stress/ anxiety sensory [hypertrophy of amygdala causes more stress and anxiety]

20
Q

Perceiving - Primary Somatosensory Cortex = SI

A

Topographic representation of sensory info from all areas of the body [aka - homoculus] - large face and hands.

21
Q

Perceiving - Secondary Somatosensory Cortex = SII

A

Functional importance of SII cortex is unknown

Bilateral presentation of body & face - large face, hand and foot areas.

22
Q

Interpreting - higher level sensory processing in Association Areas.

In parietal, occipital and temporal lobes

A

Association areas integrate info from multiple cortical areas

Integration of info allows for interpretation of info i.e. Recognition

Damage to association areas causes Agnosia (inability to recognise)

  • prosopagnosia = inability to recognise familiar faces (including patients own face)
  • semantic agnosia = inability to recognise objects by sight even though patient sees it.
23
Q

Conceptualisation

Prefrontal cortex and other high level Association Areas

A

Dorsolateral prefrontal cortex [DL-PF-C]= area for ‘working memory’, working memory is a very short term memory store

DLPFC can store info and then manipulate it - so its higher level processing rather than simply recognising.
Very important area for prioritising importance of info!!

‘What’ pathway - allows recognition of what an object is
‘Where’ pathway - allows recognition of where an object is
‘When’ pathway - allows recognition of temporal order [timing] during visual based task

24
Q

Motor Planning - Supplementary motor areas (SMA)

A

Each SMA has bilateral connections with motor cortices: biannual control

Has some projections to SC

Activates motor programs for learned movement sequences

Controls movements that are initiated internally, as apposed to in response to visual cue [throwing a ball, riding a bike]

25
Q

Motor Planning - Premotor area

A

Lateral premotor areas involved in movements activated by external stimuli [reacting to our environment - catching a ball]

Controls how stimuli are to be used to direct an action

Projections to motor cortex and SC

Left premotor cortex can inhibit right motor cortex - preventing movements by non-dominant hand during a dominant hand task

**mirror neurones in premotor area generate mirror movements (simultaneous same movement with both hands)

26
Q

Motor Planning & Activation = Basal Ganglia

A

Subdivision:

  • Caudate nucleus
  • Putamen
  • Globus palllidus [internal & external]

Projections to Thalamus, motor cortex, cerebellum and midbrain

Involved in planning, initiating/ activating, and maintaining movement
Also involved in cognition
Dopamine is the primary neurotransmitter

Loss of dopamine cells in the basal ganglia give rise to symptoms of Parkinson’s Disease

27
Q

Motor Planning & Activation = Cerebellum

A

Sends & receives projections directly from brain stem vestibular nuclei, basal ganglia, thalamus and cortex [does a lot of comparison]

Involved in:

  • Initiating/ activating automated movements, e.g. Movements used when driving
  • Comparing descending commands to ascending sensory info - error reduction
  • Integrating info from multiple brain areas
  • Coordinating movements together e.g. Walking/gait
  • Also involved in cognition
28
Q

SMA - Summary

A

Biannual control
Activates motor programs for learned movement sequences
Controls movements initiated internally

29
Q

Premotor area - Summary

A

Movements activated by external stimuli
Controls how stimuli are to be used to direct an action [associative learning]
Prevents movements by non dominant hand during dominant hand task

30
Q

Basal ganglia - Summary

A

Planning
Initiating / Activating
Maintaining movement

31
Q

Cerebellum - Summary

A

Initiating / Activating automated movements e.g. Driving
Compares descending to ascending sensory info [error reduction]
Coordinating movements e.g. Walking/gait

32
Q

Activation - Motor Cortex

A

Neurones in MC are organised typographically - so movements of different areas of the body are activated from a representative areas on motor map [homunculus]

Major projections:

  • SC = forming pyramidal tract
  • basal ganglia
  • thalamus
  • brainstem

Input from:
Premotor, SMA, basal ganglia, cerebellum, thalamus, prefrontal (striatum), sensory cortex, contralateral motor cortex.

Generally accepted that motor cortex controls movement of contralateral side of the body- although not strictly true.

33
Q

Activating - Motor Cortex = Major Descending pathways

A

Pyramidal tract consists of:

  • lateral corticospinal tract
  • anterior corticospinal tract

Also - rubrospinal tract which primarily terminate on motor neurone of the shoulder and uppper arm [i.e. Takes over from corticospinal tract] and the trunk muscles that execute postural stabilisation [and crawling in babies].
Rubro= Red nucleus in the midbrain.

34
Q

Execution - Motor neurones & muscles

A 
Motor neurones activate muscles
Muscles also under reflex control
 - golgi inhibition [role of III & IV afferents!]
 - stretch reflex
 - reciprocal inhibition
 - withdrawal reflex

Neuro - Lecture 1 - Physiology Of Motor Control (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions