Neuronal structure, function and organisation Flashcards
What are excitable cells?
Generate an electrical current by flowing through ion channels that rapidly changes the trans-membrane potential
What are the two types of excitable cell?
Nerve and muscle
What is a neuron?
A single nerve cell
What is a nerve?
Collection of neurone running together
What so neurofibrils do?
Provide cellular stability/structure
Function of axon hillock
Branches to axon itself
Function of terminals
Release neurotransmitters
Function of Schwann cells
Insulate neurons
Function of node of Ranvier
Saltatory conduction
What is the ‘all-or-nothing’ principle?
Intensity of action potential doesn’t change but firing frequency does
What is an absolute refractory period?
No action potential in this time because sodium channels inactivated
What is the relative refractory period?
Below -70mV, another AP can be stimulated but stimulus must be larger than normal because it is more negative
Why does an AP only go in one direction?
Inactivation of sodium channels (axon body to bacon terminals)
How is an AP propagated?
Sequential opening of voltage-gated ion channels
What are neurotubules?
Transport system - forms chain of tubulin running between cell body and axon terminal. Moves vesicles along the outside of the tubules using foot-like processes
What is carried from cell body to axon terminal?
Neurotransmitters, proteins and lipids
Transport molecule for going from cell body to axon terminal
Kinesin
Transport molecule for going from axon terminal to cell body
Dynein
What is carried from axon terminal to cell body?
Cell debris
Function of myelin
Electrical insulation to prevent current loss
Where does depolarisation take place?
Nodes of Ranvier
What is saltatory conduction?
Current jumps between nodes
Which nervous system are Scheann cells in?
PNS
Which nervous system are oligodendrocytes in?
CNS
Characteristics of Schwann cells
Whole cell wraps around axon
Applied to single neuron
Characteristics of oligodendrocytes
Processes from cell wrap around axon
Applied to multiple neurones
Are there Na+ channels under myelin in Schwann cells?
No, no membrane depolarisation, instead the impulse travels to the Na+ channels are the next node of Ranvier
What are satellite oligodendrocytes?
Unattached and regulate the environment
Function of oligodendrocytes
Myelination of CNS neurons
Function of astrocytes
Maintain microstructure, regulate blood-brain barrier, biochemical homeostasis, chemical communication
Function of microglia
Immune cells (e.g. monocytes), produce growth factors
Function of ependymal cells
Produce CSF, line CSF spaces, cilia aid CSF movement
What are motor nerves?
Voluntary control of movement via skeletal muscle
Are motor nerves afferent or efferent?
Efferent
What are sensory nerves?
Input carrying a variety of senses triggered by many stimuli
Are sensory nerves afferent or efferent?
Afferent
What are autonomic nerves?
Involuntary control of organs and tissues
Are autonomic nerves afferent or efferent?
Efferent
What are afferent nerves?
Towards centre
What are efferent nerves?
Away from centre
How to increase speed of conduction
Increases with myelination - saltatory conduction
Increases with larger diameter - less current loss
Peripheral matter in brain
Grey matter (cell bodies)
Central matter in brain
White matter (axons)
Peripheral matter in spinal cord
White matter (axons?
Central matter in spinal cord
Grey matter (cell bodies)
