the nervous system Flashcards
Depolarisation
Voluntary responses
mainly under conscious control, but some voluntary movements, such as walking, require less conscious attention.
the two types of involuntary response
autonomic and reflex
autonomic response
regulate the body’s internal environment
reflex response
mainly affect those muscles that are normally under voluntary control.
The 2 main components of the nervous system
- CENTRAL NERVOUS SYSTEM
- PERIPHERAL NERVOUS SYSTEM
What does the CNS consist of
- brain
- spinal chord
What does the PNS consist of
- nerves
- ganglions
What is a ganglion
A cluster of nerve cells
What is a nerve
A bundle of fibres composed of neurones that connect body parts to the CNS
What are the 2 types of neurones that the PNS consists of
- Autonomic
- somatic
What are the 2 components of automatic neurones
Sympathetic (fight or flight) and parasympathetic (rest or digest)
What happens during sympathetic responses
- heart rate increases
- blood pressure increases
- pupillary response
- adrenaline and glucose levels rise
- digestion levels decrease (less focus needed on it)
What happens during a parasympathetic response?
- blood pressure lowers
- heart rate lowers
- lower adrenal & glucose function
- increased function of digestive system
What are the components of somatic nerves
Motor and sensory
what are the main types of nerves?
- motor neurone
- sensory neurone
- inter neurone (relay)
lengths of the dendrites and axon in a motor neurone
- short dendrites
- long axon
where are the dendrites and cell body located in a motor neurone
IN the spinal chord & the axon is OUTSIDE the spinal chord
what is the function of the motor neurone
to conduct the impulse to the effector (muscle or gland)
lengths of the dendrites and axon in a sensory neurone
- long dendrites
- short axon
what is the function of a sensory neurone
- to carry messages from peripheral sense organs to the CNS
- conduct impulses to the spinal chord
where are the cell body and dendrite located in the sensory neurone?
- OUTSIDE the spinal chord
- cell body is located in the **dorsal root ganglion **
what is the function of an interneurone
- relay message from sensory neurone to motor neurone
- is used as a quick bypass since full circle is too long- used ONLY for threats
- chain between sensory & motor neurone
key features of a reflex response
- rapid
- reduces damage to tissues
- does NOT have to be learnt
function of a dendrite
- to provide a large surface area for connecting & recieving signals from other neurones.
- carry nerve impulses TOWARDS the cell body
function of an axon
- main conducting unit of the neurone
- capeable of conveying electrical signals along distances short-long
function of the cell body & nucleus
- code for & produce all the proteins for the dendrites, axons & synaptic terminals
- cell body contains specialised organelles (e.g. mitochondria, ribosomes)
function of a schwann cell
cells in the nervous system that form the myelin sheath around the neurones axon
in myelinated axons, what is the function of the unmylenated gaps(nodes of ranvier)?
allow more rapid propagation (speed) of signal along the axon (jumps gaps and changes charge)
what is a synapse
space between the presynapse & postsynapse
what do the vesicles in the presynapse contain
neurotransmitters
what are neurotransmitters
chemical substance- diffuses across the synapse
what is action potential
change in charge from - to + inside the presynaptic membrane
list the stages of an electrical impulse travelling along the synapse
see notes
what is the reflex arc
the nerve pathway which makes such a fast, involentry response possible
name the effects of chemicals (drugs) on nerve transmission
- increase number of impulses
- release neurotransmitter from vesicle without impulse
- block receptors
- produce more or less neurotransmitters
- prevent veicles from releasing neurotransmitters
