nervous coordination of muscles year 2 Flashcards
nervous system classification
nervous system is split up into central N.S and peripheral N.S
central nervous system
Contains the brain and the spinal cord.
peripheral nervous system
made up of autonomic nervous system and somatic nervous system.
somatic nervous system
The somatic nervous system communicates with sense organs and voluntary/ skeletal muscles
Contains sensory and motor neurones
autonomic nervous system
communicates with internal organs/ glands and smooth muscle.
Contains sympathetic and parasympathetic nervous system
sympathetic nervous system
Main nerve is sympathetic nerve
Main neurotransmitter is noradrenalin
Gives flight or fight response. Increases heart rate, pulmonary ventilation rate and causes pupils to dilate
parasympathetic nervous system
Main nerve is the vagus nerve
Main neurotransmitter is acetyl chlorine
Main effects is rest and digest
Has opposite effects of parasympathetic nervous system eg causes heart rate and pulmonary ventilation rate to decrease
what is resting potential?
Membrane potential difference is -70mV at rest.
how is movement of Na+ ions and K+ ions controlled
-phospholipid bilayer of the axon plasma membrane prevents sodium and potassium ions diffusing across it. This is because Na+ is hydrophilic so will repel the hydrophobic fatty acids in the membrane not allowing it to diffuse
-Channel proteins span the phospholipid bilayer. These proteins have ion channels. However, some of these channels have gates which can be opened or close so that sodium and potassium ions can move through them by facilitated diffusion. However, most of the sodium gates remain closed so most sodium ions cannot move through the membrane.
- sodium potassium pump actively transports 3 sodium ions out of the neurone, allowing 2 potassium ions to enter. This requires ATP
-most of the gates that allow the potassium ions to move trhough are open but most of the gates that allow the sodium ions to move through are closed.
how is resting potential difference established
-sodium ions are actively transported out of the axon by the sodium-potassium pump.
- potassium ions are actively transported into the axon by the sodium-potassium pump
- the active transport of sodium ions is greater than that of potassium ions
- although both are positive, there are more sodium ions in the tissue fluid surrounding the axon than in the cytoplasm, and their is more potassium ions in the cytoplasm than in the tissue fluid. This is because the outward movement of sodium is greater than the inward movement of potassium. This creates an electrochemical gradient
- the sodium ions want to move into the neurone as it is oppositely charged and they have a steep conc gradient.
- the potassium ions have a concentration gradient out of the neryibe, however there is an equal force due to the charge difference of the potassium ions and potential difference keeping them in the cell. These forces are equal so they remain in the membrane.
