6.1 Flashcards
The peripheral nervous system can be divided up into 2 systems:
Sensory
Motor
Nervous system is subdivided into the
Central nervous system
Peripheral nervous system
The motor system can be further divided into
Somatic nervous system
Autonomic nervous system
The somatic nervous system carries impulses to
Skeletal muscles that are under voluntary control
The autonomic nervous system carries nerve impulses to
Glands and muscles that are not under voluntary control
The autonomic nervous system is concerned with controlling involuntary activities in the body, such as
The beating of the heart
The secretion of sweat
Controlling the muscles in the gut
Sympathetic and parasympathetic nerves speed up or slow down the heart rate in response to
Different levels of exercise
The autonomic nervous system is subdivided into the
Sympathetic and parasympathetic systems
Both sympathetic and parasympathetic systems consist of
Motor neurones
And both sympathetic and parasympathetic send
Impulses to effectors that are not under voluntary control
The sympathetic and parasympathetic consist of 2
Neurones that connect the brain or spinal cord to effectors
The first neurone synapses with the second neurone at a
ganglion (a collection of nerve cell bodies)
How many differences are there between the sympathetic and parasympathetic nervous system?
2
First difference- in the sympathetic nervous system the ganglion is very close to the spinal cord, so that the pre-ganglionic neurone is short and post-ganglionic is long. In the parasympathetic nervous system:
The pre-ganglionic is long and the post-ganglionic is shot - the ganglion is very close to or inside the effector
Second difference: the sympathetic nervous system produces the neurotransmitter noradrenalin at the synapse with the effector whereas the parasympathetic nervous system produces the neurotransmitter
Acetylcholine at this synapse
The difference is neurotransmitter produced -
sympathetic neurones are said to be:
Parasympathetic neurones are said to be:
Adrenergic
Cholinergic
In general the sympathetic and parasympathetic nervous systems act
Antagonistically on the effector is they innervate
Antagonistic means that they have
Opposite effects
Some effectors only have a sympathetic or parasympathetic supply,
Not both
The parasympathetic system is active under
Normal conditions
The sympathetic nervous system is responsible for reacting to
Stress
Emergencies
Danger
Effects of parasympathetic nervous system:
Slows HR Dilates arteries Constricts bronchioles Contracts circular muscles in iris of eye, making pupil constrict Stimulates tear production Stimulates secretion of saliva Speeds up gut movement Relaxes bladder and anal sphincters Causes contraction of bladder
effects of sympathetic nervous system:
Speeds up HR Constructs arterioles Dilates bronchioles Contracts radial muscle in iris of eye, making pupil dilate Slows down gut movement Contracts bladder and anal sphincters Causes relaxation of bladder Contracts erector pili muscles, causing hairs in the skin to 'stand on end' Increases sweat production
