Neuronal Communication Flashcards
How does the nervous system Co-ordinate the body’s response to stimuli /what the cns vs pns does
CNS - brain & spinal cord co-ordinates response
PNS - receptors, sensory & motor neurones: connect the CNS to the external environment
What do transducers do
Convert one form of energy into electrical impulses e.g. stimulus -> nerve impulse (aka action potential)
Types of sensory receptors, the stimulus, an example of a receptor, and example of sense organs (4)
Structure of the Pacinian Corpuscle
In its resting state, stretch mediated Na+ ion channels are open or closed?
Closed, & too narrow for Na+ to pass through
How does stimulation (mechanical pressure) of the pacinian corpuscle lead to a nervous impulse
What happens if there’s a larger stimulus applying pressure on the pacinian corpuscle
- more gated Na+ channels open -> more Na+ enters the cell -> more generator potential established -> threshold potential is exceeded (at a large enough stimulus) -> action potential reached -> nerve impulse transmitted along sensory neurone
Basic general structure of neurones (cell body, dendrons, axon)
What does the cell surface membrane contain to control the entry / exit of ions (Na+, K+, Ca2+)
Many gated ion channels
Pumps use ATP to actively transport Na+ out and H+ in
What is the myelin sheath & what does it do
Fatty laye formed by Schwann cells tightly wrapping around the axon
Insulates the axon from electrical activity
Nodes of Ranvier are in the gaps of the myelin sheath (small uninsulated sections along the axon)
Sensory neurone structure
Cell body outside of CNS
Cell body branches off in middle of cell
Short axon
No dendrites
Carries action potential from sensory receptor to CNS
Myelinated!
Relay neurone structure
Motor neurone structures
Myelinated-insulated axon versus Non-myelinated
- these neurones tend to carry action potentials over larger distances
-> faster transmission of action potential along neuron - more rapid response to a stimulus
Myelinated neurones vs non-myelinated
How are nerve impulses generated
Stages of an action potential (can only travel in 1 direction)
- Stimulus occurs
- Depolarisation of membrane
- Repolarisation of membrane
- Hyperpoladisarion of membrane
- Return to resting potential
Whats saltatory conductions
How the presence of Schwann cells means the action potentials ‘jump’ from one node of Ranvier to the next (less time wasted)
Only occurs at the node as the ions can’t diffuse through the fatty layer of tightly wrapped schwann cells
Graph showing the 5 stages of an action potential
What is the significance of the refractory period
It separates impulses from one another, restricting the no, of. Impulses transmitted in a time + ensures impulses only pass 1 direction
1) what happens when the stimulus occurs
2) what happens during depolarisation
What happens during repolarisation
4) What happens during hyperpolarisation
