Physiology 1 Nerves and Neurons
Objectives:
- Be familiar with the basic anatomy of neurons and nerves
- Be familiar with the classification schemes for axons within nerves
- Understand the physiological basis of the resting membrane potential
- Understand the role and types of ion channels
Objective based questioning:
Content:
Organisation of the nervous system
CNS and PNS
from HUBS191/2 doesnt touch much on this
Neural cells has
- dendrites
- soma
- axons
- synapse Different types of neurons Dendrons
Glia
Oligodendrocytes: form myelin sheath in the CNS Astrocytes: provide nutrients, maintain extracellular environment, and provide structural support Microglia: immune response in the brain ependymal cells: circulate and produce the cerebrospinal fluid
Schwann cells myelinate in the PNS
satelite cells in PNS
Peripheral nerve
nerve is composed on fascicles which are composed of neurons Inputs and outputs are mentioned (its a physiology lecture they dont care about anatomy) pathways going uop and down
classifications of Peripheral nerves Should know this to a wellish degree
Comments on this graph Alpha motor neuron: large and heavily myelinated so very very fast
touch pressure are A beta are kinda fast
generally you can guess the speed with what the fibers are for eg olfaction and slow pain are slow, muscles are fast
c nerve fibre is really slow
Resting membrane potential
As K+ ions (which are positively charged) leave the cell, they create a slight negative charge inside the cell relative to outside. This negative charge starts to oppose further K+ efflux.
The cell reaches equilibrium (RMP) when the electrical force pulling K+ into the cell exactly balances the concentration gradient pushing K+ out of the cell. In most cells, this occurs at around -70 mV.
Electrochemical gradient
Goldman-hodgkin-Katz equation
RMP is highly sensitive to changes in K as k is th ebig dick in the room when it comes to RMP
Clinical note
when neurons die they release K+ which hurts more of the brain over time
Types of ion channels
Voltage gated ion channel
Mechanically gated ion channel
Chemically gated ion channel nicotinic vs muscinaric
Nicotinic is directly gated to the channel
Muscinaric is through a G protein to open the channel