Human Movement and Sensation Flashcards
What does the Central Nervous System consist of?
Brain and spinal cord
What does the peripheral nervous system consist of?
Peripheral nerves
What is composed of neurons and glia?`
All parts of the CNS and PNS
What are neurons?
Nerve cells
What is the purpose of Neurons?
Cells specialised for transmission of information
What are the functions of the glia?
Support for neurons
What are the structures of the neuron? (4)
Dendrites
Cell body
Axon
Axon terminal
What is the function of a dendrite?
Recieve input
Send information to the cell body
What is the function of the cell body?
Contains nucleus and organelles
Sums input
What is the function of the Axon?
Carries electrical impulses
May or may not be myelinated
What is the function of the axon terminal?
Terminal end of the axon for neurotransmitter release
What is a group of cell bodies called? (CNS)
Nucleus
What is a bundle of axons called? (CNS)
Tract
What is a group of cell bodies in the cerebral cortex or the spinal cord called?
Grey matter
What is a bundle of axons in the cerebral cortex or spinal cord called?
White matter
What is a group of cell bodies called in the PNS?
Ganglion
What is a bundle of axons called in the PNS?
Nerve
What is the input zone of a neuron?
Dendrites and cell body (receives chemical signals from other neurons)
What is the summation zone of a neuron?
Axon hillock
What is the conduction zone of the neuron?
Axon - quite long.
Carries signals from brain areas, spinal cord, or from peripheral sensory receptors.
What is the output zone?
Axon terminals
Contact with input zone of other neurons or effectors.
Release of neurotransmitters
What are the 4 morphological types of neurons?
(DRAW SLIDE 1)
Multipolar
Bipolar
Unipolar
Anaxonic
What is the structure of a multipolar neuron
Multiple processes emanate from the cell body
Lots of places where dendrites stick out of cell body
What is the structure of a bipolar neuron?
2 processes emanate from the cell body
What is the structure of a unipolar neuron?
Once process emanates from the cell body.
Branches into dendrite and axon
What is the structure of an anaxoic neuron?
No distinct axon
All processes look alike
What are the 3 features of astrocytes?
Supply nutrients to neurons
Ensheath blood capillaries
Injury response
What is the function of a microglia (2)?
Immune cells of the CNS
Engulf microorganisms and debris
What are the 2 function of ependymal cells?
Line fluid-filled spaces of brain and spinal cord
Have cilia to circulate CSF
What are the 2 functions of Oligodendrocytes?
Support nerve fibres
Ensheath them with myelin
What is the function of glia in the PNS?
Support peripheral nerve fibres
Ensheath them with myelin
What are the 4 types of glia in the CNS?
Astrocytes
Microglia
Ependymal Cells
Oligodendrocytes
What is the Schwann Cell?
Plasma membrane wrapped around an axon
What is a myelin sheath?
Lipid fat around an axon
What is the function of a myelin sheath?
Increases conduction velocity
What is a node of Ranvier?
Gaps between myelin
Increase conduction velocity
What is a synapse?
Neurotransmitter release between neurons
What is a synaptic cleft?
When the signal is changed from electrical, to chemical, to electrical, between neurons.
What is a synaptic vesicle?
Little packets of neurotransmitter in presynaptic neuron
What is it called when information goes into the brain
Afferent (ascending)
What is a response that comes out of the brain called?
Efferent (descending)
What is the myelin sheath in the CNS made up of?
Oligodendrocytes
What is somatic in terms of information transmitted?
They are the stuff that we are aware of?
What is an example of somatic efferent?
Running
What is an example of somatic afferent?
Seeing
What is autonomic?
Involuntary
What is an autonomic efferent example?
Heartbeat
What is an autonomic afferent example?
Blood pressure
What is the upper motor neuron located?
Cell body in brain
Axon in spinal cord
Where is the lower motor neuron located?
Cell body in the spinal cord
Axon in the spinal nerve
Is the upper or lower motor neuron myelinated?
Both are myelinated
What is the neurotrasmitter responsible for communication between effector cells?
Ach (Acetylcholine)
What is the effector for the somatic efferent division?
Skeletal muscle
What are the 2 divisions of the autonomic efferent nervous system?
Sympathetic
Parasympathetic
What are the effectors of the Autonomic Efferent nervous system? (4)
Smooth muscle and cardiac muscle
Glands, adipose (fat)
Where is neuron 2 of the autonomic efferent nervous system
Cell body in brain or spinal cord
Axon in PNS
Where is neuron 3 in the autonomic efferent nervous system?
Cell body in the PNS
Axon in the PNS
Is neuron 2 myelinated or unmyelinated?
Myelinated
What neuron 3 myelinated or unmyelinated
UNmyelinated
Where does neuron 2 synapse?
Autonomic ganglion
Is neuron 2 pre- or post-ganglionic?
Pre-ganglionic neuron
Where does neuron 3 synapse?
Effector organ
Is neuron 3 pre- or post-ganglionic?
Post-ganglionic neuron
What is the neurotransmitter for neuron 2?
ACh
What is the neurotransmitter for neuron 3?
ACh or norepinephrine (NE)
What is the function of the sympathetic nervous system?
Prepares body for stress responses e.g. fight or flight
What is the function of the parasympathetic nervous system?
Prepares body for restful situations
What is the neurotransmitter for the sympathetic nervous system?
NE
What is the neurotransmitter for the parasympathetic nervous system?
ACh
What ganglion (para/sympathetic) has a short preganglionic axon and a long postganglionic axon?
Sympathetic
What ganglion (para/sympathetic) has a long preganglionic axon and a short postganglionic axon?
Parasympathetic
What ganglion (para/sympathetic) is close to the CNS?
Sympathetic
What ganglion (para/sympathetic) is far from the CNS?
Parasympathetic
Where are the sympathetic chain ganglia located?
On either side of the vertebral column
How many pairs are there in the sympathetic chain ganglia?
21-23
How long are the fibres of the sympathetic pathway?
Preganglionic (short)
Post (long)
How long are the fibres of the parasympathetic pathways?
Preganglionic (long)
Post (short)
Where is the preganglionic sympathetic pathway located?
Spinal cord (thoracolumbar)
Where is the postganglionic sympathetic pathway located?
Sympathetic chain
Where is the preganglionic parasympathetic pathway located?
Craniosacral (brainstem)
Where is the parasympathetic postganglionic pathway located?
In or near effector
How does a chemical signal get converted into an electrical signal?
A chemical signal (transmitter) opens chemically gated ion channels by binding to them, allowing Na and K to flow.
If -60mV is reached, action potential will begin
How are chemically gated ion channels closed?
Neurotransmitter unbinds
How are voltage-gated ion channels opened and closed?
Membrane is depolarised causing it to open.
Once membrane threshold is changed, the channel will inactivate or close
How are mechanically gated ion channels opened and closed?
Stretch or squish causes the membrane to deform, causing the channel to change shape.
When the membrane returns to the original shape, the channel closes.
What are the chemically gated ion channels in a neuron?
Dendrites and cell body
What are the voltage gated ion channels in a neuron?
Axon hillock, axon, and axon terminals
What is the charge of the inside of a cell regularly?
-70mV
Which direction will sodium move if Na+ channels are opened?
Into the cell
What is a local potential?
Change in membrane potential voltage in a localised area.
How does a local potential occur?
Neurotransmitter binds and opens chemically-gated ion channels on dendrites/ cell body, either allowing Na in or K out.
What are the two forms of local potential?
Excitatory or Inhibitory
How does an EPSP form?
Excitatory local potentials form when a presynaptic neuron releases an excitatory neurotransmitter which opens Na gates, causing Na to enter and the cell to depolarise.
What causes IPSPs to form?
When a presynaptic neuron releases an inhibitory neurotransmitter, which opens K gates, causing K to leave the cell and hyperpolarise.
What are the two ways that local potentials can be summed?
Spatial and Temporal Summation
Describe spatial summation
This is the sum of the input from multiple presynaptic neurons
Describe temporal summation
This is the sum of the input from the repeated firing of one pre-synaptic neuron