L17- introduction to nerve cells and excitability

what are neurons

• they are specialised cells in the nervous system that transmit information throughout the body

• the most common type is the motor neurons

• the majority of them are found int he brain and the spinal cord

• they aren’t able to regenerate

• they are classified by their function or their shape 

neuron structure

describe the movement of signals

the signals go from the dendrites its then processed in the cell body then its moved through the axon 

after the information is processed and released in the synaptic terminals 

describe how you classify neurons 

• draw a circle around the cell body of the neurons  

• then draw how many dendrites are present 

• if you have one axon then many dendrites its a multipolar neuron 

• if you have one cell body with one dendrite and one axon its a bipolar neuron 

• if you have one cell body with one projection its unipolar 

what are the three types of neurons and their functions

• afferent ( sensory )= transmits signals to the CNS

• efferent ( motor )= sends commands from the CNS to the muscles/glands

• interneurons= processes information within the CNS

what is meant by-” neurons are excitable cells”

they can generate electrical signals in response to stimuli

what is the resting membrane potential 

• it is the electrical charge difference across the membrane of a neuron when a signal isn’t being sent

• the inside is more negative then the outside 

explain how the membrane controls ion movement

• all cells have a outer phospholipid bilayer that regulates what charged ions or proteins enter as its selectively permeable

• so only specific ions are able to enter and leave through channels and pumps

describe how ions move across a membrane

• they move across a membrane using channels and pumps

• in channels the ions diffuse down a concentration gradient from high concentration to low concentration

• in pumps the ions are moved against concentration gradient

• and they can be used to gradient and they require ATP

explain how sodium-potassium pumps maintain excitability/ resting potential 

• the sodium-potassium pump moves 3Na⁺ out for every 2 k⁺ that goes in the membrane 

• the resting potential is -70Mv

• The sodium voltage gated ion channels are all closed allowing no sodium ions to renter the membrane whilst some potassium ions are able to leak back through their channel 

how do you calculate the equilibrium potential for any ion ( E_ion ) nernst equation

how do you calculate the resting membrane potential Vm