nervous system

what is the nervous system

a bodywide system of nerve cells that collect information from the world. process it, and take action via directing bodily organs and muscles

what is the nervous system divided into

the Central Nervous System (CNS)

the Peripheral Nervous System (PNS)

what are the parts of the CNS

the brain- all conscious and most unconscious processing

Spinal Chord- recieves and transmits info, some reflex processing 

What is the Peripheral nervous system and its function

A bodywide network of messenger neurons

sensory to CNS and motor from CNS 

what is the PNS split into

Somatic nervous system- skeletal muscles, voluntary system

Autonomic nervous system- Internal organs and glands, involuntary system, split into 2 parts

what are the 2 parts of the Autonomic nervous system

Sympathetic- stress response- stimulates body

Parasympathetc- rest- calms body

what is homeostasis

Regulation of the internal environment. In normal conditions there is a balance between the sympathetic and para sympatheic systems. This is called maintaining homeostasis 

what pathway does the reflex arch follow

sensation is detected by sensory receptors in the sensory nerve (SN)

electrical signal moves along dendrite to axon terminal

moves as a chemical signal from the SN to the relay neuron accross the synapse 

Moves through a synapse to the motor neuron and to CNS (but later to avoid nerve damage) 

Signal reaches effector- muscle or gland- which shows the effect

what is another term for the electrical impulse

action potential

what are the 3 types of neuron

sensory neuron

relay neuron

motor neuron

what are the parts of a neuron

dendrites 

nucleus 

cell body

axon

myelin sheath

axon terminal

what is the function of a dendrite

recieves signals from other neurons or sensory receptors

what is the function of the cell body

the control centre of the neuron

wehere the action potential leaves from

what is the function of the axon

the action potential travels along this to the axon terminal

what is the function of the myelin sheath

to insulate the axon to allow for faster transmission

which neuron is which

what is the function of the sensory neuron

to carry nerve impulses from sensory receptors to the spinal chord and brain where the impulse is translated into sensations 

those to the spinal chord are for reflex action 

what is the function of the relay neuron

allow sensory and motor neurons to communicate with each other

Lie entirely in the brain and spinal chord

what is the function of the motor neurons

responsible for muscle contreaction

cell body located in the motor cortx, brainstem, or spinal chord

Axons project to and outside of the spinal chorrd and have synapses with muscles and glands 

neurotransmitters are released which bond to muscles and trigger muscle contraction

what is synaptic transmission

the movement of an action potential between neurons as neurotransmitters across a junction called the synapse

what occurs during synaptic transmission for neurotransmitters to enter the synapse

ie step 1-2

synaptic vesicles at the end of the presynaptic axon contain neurotransmitters 

the action potential releseas the vesicles and neurotransmitters are releases into the synaptic gap by exocytosis

what occurs during synaptic transmission for the signal to pass to the second neuron

ie stages 3-5

neurotransmitters diffuse across the gap and bind onto specialised receptors on the surface of the postsynaptic neuron

once activated, receptor molecules have excitatory or inhibitory effects on the postsynaptic neron

the quicker the re-uptake of the neurotransmitter into the presynaptic neuron, the shorter the effect

what are the types of neurotransmitter

there are many different types but all are either excitatory or inhibitory 

what are excitatory neurotransmitters

neurotransmitters which trigger nerve impulses to stimulate the brain into action

what are inhibitory neurotransmitters

neurotransmitters which slow nerve impulses to calm the brain and balance mood

examples of excitatory neurotransmitters

dopamine and noradrenaline

make postsynaptic cell more likely to fire

example of inhibitory neurotransmitter

GABA 

acts as an off switch making the postsynaptic cell less likely to fire