Neuronal transmission Flashcards
whats a Pacinian Corpuscle ?1
pressure sensor found in the skin
outline the structure of a motor neurone ?
2
- large cell body in CNS
- long axon carries AP to the effector
outline the structure of the sensory neurone ? 3
- long DENDRON
- cell body is just outside the CNS
- SHORT axon to CNS
Outline the structure of a relay neurone ?
3
1-short dendrites (short and fat looking )
2-short axon
3-in CNS
why does having a myelin sheath speed up the transmission of an AP ? 3
1-Myelin sheath is made of Schwann cells
2-myleinated neurones = gaps called Nodes of Ranvier (where movement of ions can occur )
3- this makes the impulse jump from node to node = RAPID
4- SALTOTORY CONDUCTION
outline the difference between sensory and motor neurones ?
1-
what are the stages of an action potential ?
3
1- Depolarisation
2-repolarisation
3-hyperpolarization
resting potential ? —-
threshold potential ?—–
1- resting = -60mV
2-Threshold = -10mV
what happens in the membrane when the Na/K pump is in use ? 3
-only Na/K pump is working ( 2 K out and 3Na in )
-Na+ channels closed
the concentration of Na is higher outside ( so inside is more negative )
what happens during Depolarisation ? 2
1- Na+ channels open and Na+ diffuses into the cell
2-the membrane depolarises = has a less negative potential ACROSS the membrane !
3- IT reaches threshold = the VOLTAGE GATED NA+ channels open due to positive feedback and many more na+ seep out into the cell so the potential is now +
4-+ 40mv is reached
what happens during Repolarisation ? 4
1- Na+ channels close / K+ channels open
2-K+ channels move out of the cell making the outside more positive and the inside more negative
3-a more negative potential is gradual reached .
4-it can overshot and become hyperpolarized so the pump will help restore this !
what direction does k+ diffuse ?
na+ channel movement of na + ?
- K+ channels allow the k+ to diffuse from high to low concentration= Always from INSIDE –> OUTSIDE !
-Na+ will always move from the outside to the inside of a cell .( higher concentration outside of the cell ) - Natural setting : more k+ inside cell and More Na+ outside cell.
(remember that outside of cell is salty (more na+ on outside ))
whats the refractory period and why is needed?
- at the end of an AP the K+ and Na+ ions are in the wrong places!
- there is k+ on the outside of the cell and Na+ on the inside of the cell !
- so to fix this we have a pump ! Na/K pump !
- this also requires some time = REFRACTORY period !
- this also makes sure that the AP goes in the right direction
whats it called when one neurone branches to many neurones? 1
- spatial summation (many to one ) (one to many)
- (several Generator potentials cause AP)
whats is called when one neurone keep sending several APs ?
- temporal summation
bang bang bang
