neuro - (physiology and electrical activity) Flashcards
What are the three parts of a neuron?
- Dendrite
- Cell body
- Axon
Central Nervous System consists of:
- brain
- spinal cord
2 types of cells in the nervous system:
- neuroglia
- neurons
what is the function of the cell bodyÉ
- contains the nucleus
- creates macromolecules
- consolidates information from the dendrites
what is the function of the dendrites?
receptive area - transmit messages to cell body
what is the function of axons?
conduct pulses (action potentials) away from the cell body
what is the function of myelin sheaths?
- insulate the neuron
- increase conduction speed of action potentials
why do myelinated axons have faster conduction speeds
- myelination prevents the movement of Na+/K+ (thus preventing action potentials)
- less action potentials are required to conduct the message down the neuron than unmyelinated neurons
- also thicker and more cable-like
what is the function of the synapse?
the functional connection between the neuron and the second cell
what is the axon hillock?
the origin of the axon (where the cell body becomes the axon)
Which direction do afferent neurons carry information
INTO the CNS from SENSORY RECEPTORS
Which direction do efferent neurons carry information?
OUT of CNS to EFFECTOR ORGANS
What do somatic motor nerves control? Do we have control of these nerves?
- Skeletal muscles
- Yes
- cardiac muscle, smooth muscle and gland secretion is controlled by the ______________
autonomic nervous system
What are the two types of neuroglia in the PNS?
- Schwann cells
- Satellite Cells
What is the function of Schwann cells?
Form the myelin sheath around axons
What is the function of satellite cells?
Support of neuron cell bodies within ganglia of the PNS
What are the four types of neuroglia in the CNS?
- Oligodendrocytes
- Microglia
- Astrocytes
- Ependymal Cells
What is the function of microglia?
move around CNS and phagocytose foreign and degenerative material
What is the function of astrocytes? (4)
- Regulate the external environment of neurons
- needed for the formation of synapses in CNS
- formation of blood-brain barrier
- regulate neurogenesis in adult brain
What is the function of ependymal cells?
epithelial cells that line the ventricles of the brain and canal of the spinal cord
What are the two types of cells that form the myelin sheaths and which nervous system are each of them in?
oligodendrocytes (CNS)
Schwann cells (PNS)
What is the neurilemma and which nervous system is it in?
the continuous sheath of Schwann cells lining the axons in the PNS
What are the unmyelinated regions in between myelinated regions on an axon called?
nodes of ranviers
what is the function of the nodes of ranvier?
conduction of the nerve impulses down the axon
Is axon regeneration more common in the PNS or CNS?
PNS
What are the steps of axon regeneration in the PNS?
- severed axon degenerates
- Schwann cells phagocytose severed axon
- Schwann cells form the regeneration tube
- The growing axon connects to the cell body because it is attracted to the chemicals secreted by the Schwann cells
- Regeneration tube helps guide the new axon to its destination
Why is regeneration of axons less common in the CNS?
- death receptor production after injury of the spinal cord
- prevented by inhibitory proteins in the myelin sheath membranes
- (old myelin is rapidly phagocytosed by Schwann cells, preventing the production of inhibitory proteins in PNS)