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NAS > Week 2 > Flashcards

Week 2 Flashcards

1
Q

What are afferent neurones

A

Carry info from sensory receptors of the skin and other organs to CNS

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2
Q

What are efferent neurones

A

Carry motor info away from CNS to the muscles and glands of the body (PNS)

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3
Q

Where is the cell body located in Afferent neurones

A

Outside the spinal cord in the dorsal root ganglion
Cell body has a single axon that divides into 2 branches , one connected to sensory organ and another that carries sensory info to spinal cord via dorsal root

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4
Q

Where is the cell body located in efferent neurones

A

In the ventral horn of the spinal cord
Efferent axons leave spinal cord through the ventral root travel through spinal nerves and synapse with skeletal muscle cells found in neuromuscular junction

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5
Q

What is autonomic division

A

Regulates involuntary body responses

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6
Q

What is somatic division

A

Voluntary movement by skeletal muscles

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7
Q

What is the CNS

A

Brain and spinal cord

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8
Q

What is PNS

A

The nervous system outside the CNS
Connects sensory to CNS
Contains ganglia- collection of neuronal bodies found in the voluntary and autonomic branches of the peripheral nervous system

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9
Q

What are the three main types of neurones

A

Multipolar
Bipolar
Pseudo-unipolar

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10
Q

What are multipolar neurones

A

Motor/efferent
Single axon, many dendrites

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11
Q

What are bipolar neurones

A

Relay or special sense
One axon and one dendrite

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12
Q

What are pseudo-unipolar neurons

A

Sensory
Impulses don’t have to go through the cell body, one extension from its cell body
can go from dendrites to synapse
This neuron has an axon that’s split into two branches one to PNS and other to CNS

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13
Q

What are glial cells

A

Predominant cell type within the CNS
Responsible for creating optimum microenvironment for neuronal activity
Four main types:
Astrocytes
Microglia
Ependymal
Oligodendrocytes

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14
Q

What are astrocytes

A

Star shaped
Contribute to the blood-brain barrier
Most abundant cell type
Provide structural and metabolic support, provide nutrients to neurones such as cholesterol
Two types- fibrous (white matter), protoplasmic (grey matter)

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15
Q

What are microglia

A

Immune function- phagocytosis
Exist in 2 forms:
Resting (ramified)
Activated- phagocytic
Maintain brain homeostasis
Dysregulation can lead to neurological disease
Prevent pathogens entering CNS, clear dead neurones

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16
Q

What are ependymal cells

A

Simple ciliated epithelial cells lining the ventricles
Cerebrospinal fluid synthesis
Provides nutrients creates environment needed
Movement of cilia helps regulate CFS

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17
Q

What are oligodendrocytes

A

Only in CNS
Cells with few processes
Create myelin sheaths around neurones in the CNS
Provide metabolic support and electrical insulation
Have the ability to myelinate several neurons at a time

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18
Q

What are Schwann cells

A

Only in PNS
Myelinate one axon
Create myelin sheaths around neurones in PNS
Provide metabolic support and electrical insulation

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19
Q

What is myelination

A

Myelin is a lipid sheath 0.5-2.5 micrometers thick
Created by glial cells which surrounds axon of a neurone
Increases speed of conduction, provides protection and structural support
Saltatory conduction
Created by oligodendrocytes in CNS Schwann cells in PNS

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20
Q

Unmyelinated neurons

A

Axons are still surrounded by Schwann cells
The Schwann cells have a more supportive role
Myelin sheath doesn’t totally encapsulate neuron

21
Q

What is the somatic nervous system

A

It’s a unique collection of tissues of the nervous system
Under direct command of the human organism- voluntary division of NS
It allows us to accurately localise sensations throughout the extent of the body
Also gives us awareness of our body position in 3D - proprioception

22
Q

What are three muscle types

A

Skeletal (somatic)
Smooth- autonomic
Cardiac-autonomic

23
Q

What are neuromuscular junctions/ motor end plates

A

Conduct stimuli to skeletal muscle

24
Q

What is a fascicle

A

axon bundles

25
Q

What is a nerve

A

Multiple fascicles of axons

26
Q

What does the neuron consist of

A

Body (soma or perikaryon)- contains two structures Nissl substance and cytoskeletal components
Dendrites- multiple covered by dendritic spines, travels to the cell body
Axon- terminal portion has branches, each has a synaptic ending, away from the cell body

27
Q

What are anaxonic neurons

A

Contain no axon
In CNS has coordinating function between neurons
Do not produce action potentials but regulate local electrical changes of adjacent neurons within brain or spinal cord

28
Q

What do macrophages in the body tissues develop from

A

Monocytes in the blood flow that originate from the red bone marrow which would have had an embryonic precursor
This embryonic precursor cell also serves as an organ for microglia
So also are phagocytic cells and immunoprotect the brain and spinal cord

29
Q

What is the function of microglia cells

A

To keep environment clear of debris, if infection occurs they become activated
They can phagocytose

30
Q

Where are satellite and Schwann cells present

A

Only in PNS

31
Q

What are the functions of satellite cells

A

Electrically insulates PNS cell bodies
Regulates nutrient and waste exchange for cell bodies in ganglia

32
Q

What are the functions of neurolemmocyte

A

Surround and insulate PNS axons and myelinate those having large diameters
Allows for faster action potential propagation along an axon in the PNS
Neurolemmocytes also known as Schwann cells are glial cells found in the PNS

33
Q

What is the epineurium

A

Outermost layer, covers the entire nerve

34
Q

What is the perineurium

A

Separates nerves into fascicles and consists of neuroepithelial perineurial cells which are joined to each other by tight junctions to form the protective diffusion barrier
The blood-nerve barrier, responsible for maintaining the physiologic microenvironment of the endoneurium

35
Q

What is the endoneurium

A

Surrounds individual axons and their associated Schwann cells

36
Q

What is the electrical synapse

A

Fastest and most primitive
Between adjacent cells or neurites
Direct transfer of ionic current
Bi-directional
Allows synchronous activity
Relatively rare between neurons in the CNS
Glia-neuron, glia-glia communication

37
Q

What is the chemical synapse

A

Close association between the presynaptic and the post synaptic membrane
Presynaptic terminal releases neurotransmitter
Diffuses across the synaptic cleft
Interacts with receptor on the postsynaptic membrane
Unidirectional transfer of information

38
Q

How does a synapse work

A

Action potential invades nerve terminal sodium ions move in
Depolarisation triggers Ca2+ channel opening, calcium influx
Neurotransmitter release by exocytosis (Ca2+ dependent)
Diffusion across the synapse and receptor binding on postsynaptic membrane
Post synaptic effect
Rapid termination of signal by reuptake of neurotransmitter or enzymatic breakdown

39
Q

Neurotransmitter receptors

A

Membrane spanning protein molecules
Transmitter binding causes structural/conformational change=signal
Receptors are specific for a neurotransmitter
One neurotransmitter- several receptor subtypes

40
Q

Types of receptor signalling mechanisms

A

Ionotropic (receptor operated/ ligand gated channels)
Metabotropic G-protein coupled)

41
Q

What is ionotropic

A

Transmitter binding
Conformational change
Channel opening
Ion movement

42
Q

What is metabotropic

A

Transmitter binding
Conformational change
Activates G-protein
Activates ‘effector systems’
Indirect effects e.g. open or close ion channels, stimulate or inhibit enzymes/ secondary messenger systems

43
Q

what is spatial summation

A

Summing of post synaptic potentials generated at separate synapses

44
Q

What happens when the threshold is reached

A

Voltage dependant Na+ channels open
Action potential generated

45
Q

What is temporal summation

A

Summing of post synaptic potentials generated at same synapse, if they occur in rapid succession

46
Q

What is the specific functional modality of the majority of axons of a ventral root

A

Motor (somatic) neurone

47
Q

EPSP

A

Excitatory post synaptic potential

48
Q

IPSP

A

Inhibitory post synaptic potential

NAS (12 decks)

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