Neurons Flashcards
What are the major parts of a Neuron?
- Cell body
- Dendrites
- Axon
- Presynaptic terminal
What is a Neuron?
A Neuron is a specialised cell used for transmitting nerve impulses
What is the axon?
The axon is the information sender of the Neuron, conveying an impulse toward other Neurons
What is a myelin sheath?
A myelin sheath is an insulating material that covers the axon, it has interruptions know as nodes of ranvier.
Where and what is a presynaptic terminal?
The pre synaptic terminal is at the end of the axon. This is the point from which the axon released chemicals that cross through the junction between one Neuron to the next.
What is the different between an afferent axon and an efferent axon?
An afferent axon brings information to a Neuron; an efferent axon carries information away from a Neuron.
What builds the myelin sheath?
Oligodendrocytes in the brain and spinal cord and Schwann cells in the periphery are specialised types of glia that build the myelin sheath.
What is Extracelluar fluid?
Fluid outside the cell
What is intracellular fluid?
Fluid outside the cell
What are examples of fluid with the cell?
Sodium, potassium and chloride
What are ions?
Molecules with an electrical charge
What is an anion?
A negatively charged ion (Cl -)
What is a cation?
A positively charged ion (Na + K +)
What is the charge of a resting potential?
-70 my
What is the charge of the action potential?
+40 my inside the Neuron
What is electrostatic force?
Two ions with the same charge will repel each other
What is diffusion?
Ions move from area of higher concentration to area of lower concentration
What is the sodium potassium pump?
A membrane protein which removes sodium
What are channels?
Small pores on the membrane which are closed when neurone is at rest. When the neurone receives a signal, sodium channels open causing sodium to enter the neurone - if enough sodium channels open and the inside becomes - 60 my then an AP will fire - more sodium channels open and sodium rushes in causing the inside of the cell to become + 40 mv relative to outside of the cell
What happens at the presynaptic terminal?
AP arrives at the pre synaptic terminal and causes calcium channels to open - calcium influx causes the vesicles to fuse with pre synaptic membrane and the neurotransmitters are released in to the synaptic cleft. This is called exocytosis. Neurotransmitters diffuse across the synaptic cleft and attached to receptors on the post synaptic membrane
What are receptors?
Receptors are membrane proteins which open ion channels
What are agonists?
Agonists are drugs which mimic and potentials neurotransmitters action
What are antagonists?
Antagonists are drugs which block and reduce neurotransmitters action
What is an IPSP?
Inhibitory post synaptic potential - if channel let sin negatively charged ions it makes the neurone less likely to fire
