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Week 2 Flashcards

(48 cards)

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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

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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

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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

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A

Skeletal (somatic)
Smooth- autonomic
Cardiac-autonomic

23
Q

What are neuromuscular junctions/ motor end plates

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A

Conduct stimuli to skeletal muscle

24
Q

What is a fascicle

25
What is a nerve
Multiple fascicles of axons
26
What does the neuron consist of
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
What are anaxonic neurons
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
What do macrophages in the body tissues develop from
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
What is the function of microglia cells
To keep environment clear of debris, if infection occurs they become activated They can phagocytose
30
Where are satellite and Schwann cells present
Only in PNS
31
What are the functions of satellite cells
Electrically insulates PNS cell bodies Regulates nutrient and waste exchange for cell bodies in ganglia
32
What are the functions of neurolemmocyte
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
What is the epineurium
Outermost layer, covers the entire nerve
34
What is the perineurium
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
What is the endoneurium
Surrounds individual axons and their associated Schwann cells
36
What is the electrical synapse
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
What is the chemical synapse
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
How does a synapse work
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
Neurotransmitter receptors
Membrane spanning protein molecules Transmitter binding causes structural/conformational change=signal Receptors are specific for a neurotransmitter One neurotransmitter- several receptor subtypes
40
Types of receptor signalling mechanisms
Ionotropic (receptor operated/ ligand gated channels) Metabotropic G-protein coupled)
41
What is ionotropic
Transmitter binding Conformational change Channel opening Ion movement
42
What is metabotropic
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
what is spatial summation
Summing of post synaptic potentials generated at separate synapses
44
What happens when the threshold is reached
Voltage dependant Na+ channels open Action potential generated
45
What is temporal summation
Summing of post synaptic potentials generated at same synapse, if they occur in rapid succession
46
What is the specific functional modality of the majority of axons of a ventral root
Motor (somatic) neurone
47
EPSP
Excitatory post synaptic potential
48
IPSP
Inhibitory post synaptic potential

NAS (12 decks)

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