6: Autonomic nervous system Flashcards
Define and explain dual innovation
organ that uses both sympathetic and parasympathetic divisions
- generally have opposing effects
- they counter balance to control organ function
- on will predominantly work and the other follows
Sympathetic control is
- prepares body for heightened activity
- exercise, excitement, emergency, embarrassment
- fight or flight
examples of sympathetic control in the body
Heart= increased rate and strength of contraction
lungs= bronchiole dialation
sweat glands= increase sweat
eyes= isis dilates, lense flatterns= adjust vision
Parasympathetic control is
- stimulates abdomnal viceral activity.
- conserve energy- rest and digest
- not all organs have parasympathetic function
examples of parasympathetic control in the body
heart= decreases heart rate= blood pressure decreases
lungs= bronchiole constriction
eyes= iris constricts lense thickens/concaves to adjust vision
Are somatic and autonomic afferent or efferent?
efferent meaning the pass on motor control
How do autonomic and somatic differ?
1- neural pathway (how effector gets to target)
2- effects (target organs)
3- Organ responses
4- neurotransmitters (NT)
Describe somatic nervous system pathway
control centre= primary motor cortex (input from cerebellum and basal nuclei) CNS=upper motor neuron PNS= lower motor neuron Target= skeletal muscles Function= voluntary movement and somatic reflexes
Describe the autonomic nervous system pathway
control centre= hypothalamus (input from limbic system and cerebrum) CNS= interneurons PNS= pre and post ganglionic neurons Target= glands, smooth and cardiac muscles Function= involuntary control - viceral organ function - glandular activity
- viceral reflexes
Where are somatic cell bodies located?
- spinal cord motor nucleus (anterior grey horns) exit via spinal nerves
- brainstem nucleus that exit via cranial nerves
Where are autonomic cell bodies located?
- spinal cord motor nucleus and exit via ventral root spinal nerves
- brain stem nucleus exit via cranial nerves
Define a Neurotransmitter
transfer signal either from on neuron to another (preganglionic) or from myeline to myeline.
Role of ACh
released by preganglionic neurons and travels to post ganglionic neuron which it bind to receptors on the surface and releases which creates an action potential in postganglionic neuron which is how the signal is passed on.
Similarities between sympathetic and parasympathetic
- Serve many of the same organs
- Involve pre and post ganglionic neurons
- Preganglionic neurons release Ach
- Presence of Ganglia
Differences between sympathetic and parasympathetic
- Both divisions do not innervate all organs
- Location of preganglionic cell bodies and axon points from CNS
- Length of axons
- Location of the ganglia.
Alternative names for para and sympathetic systems
parasympathetic= carniosacral
due to the fact that the nerves leave at the brain stem or base of cranium and at the sacral region.
sympathetic= thoracolumbar
due to the nervces leaving the spinal cord through the
Parasympathetic division
Aka. Craniosacral division
structure
Preganglionic neurons arise from opposite ends of the CNS.
- brain stem-> axon exits CNS via cranial nerves - Sacral region of spinal cord (S2-S4)-> axon exit via spinal nerves (ventral root) - ganglia located close to target organ
Preganglionic axon= long
Post ganglionic axon= short
carinial pathways controls facial, vagus and oculomotor nerves
sacral pathways control
- pelvic organs
- distal portion of intestines
Sympathetic division aka thoracolumbar division structure
Preganglionic fibres arise within spinal card segments T1-L2
- Cell bodies are in motor nuclei of lateral gray horns.
- Axons exit spinal cord via spinal nerves (ventral root)
- ganglions located close to the spinal cord
Preganglionic axon= short
Postganglionic axon= long
**This is a clear anatomical difference to the parasympathetic system.
Define sympathetic trunk
- Where cell bodies of postganglionic
Lie next to vertebral column in a trunk. One lies on both sides of spinal cord… aka sympathetic trunk ganglia
Explain the adrenal medulla
Adrenal glands=
- Sit on top of kidney - Outer region called cortex which produces hormones - Inner religion medulla produces adrenalin (A)and Noradrenalin (NA)
To produce nor/adrenalin;
1. Sympathetic, preganglionic neuron that arises from the thoracic and lumbar spinal cord. The axon inivated cells in the adrenal medulla which release acetylcholine and an axon potential arrives at the axon terminal.
2. Acetylcholine binds to nicotinic receptors on adrenal medulla cells.
3. Ach stimulated medullary cells in kidney to release nora/adrenalin into the blood stream.
4. These two neuro transmitters now acting as hormones can activate every sympathetic target that has a receptor for nora/adrenaline.
- This enhances sympathetic response as lots of targets can be activated.
Because chemicals iin the blood spread the response it prolongs the response.
A short lives nervous response is turned into a much longer adrenal/hormaonal response.
Benefits of sympathetic activation
Benefits of sympathetic activation
- Adrenal medulla releases nora/adrenaline to enhance effects of four e's (exercise, emergency, excitement, embarrassment ). By enhancing and prolonging sympathetic effects. - A single preganglionic neuron can synapse with multiple post ganglionic neurons which activates multiple effectors. - Sympathetic effects= wide spread Parasympathetic effects= focused
What NT do preganglionic transmitters release?
ACh
What NT do post ganglionic nerves release?
sympathetic= Na (adrenalin to go fast like like skeletal muscles do when you run) Parasympathetic= ACh
Receptors that bind acetylcholine are called?
Cholinergic receptors
Receptors that bind nor/adrenalin are called?
adrenergic
What are the two types of cholinergic receptors?
nicotinic and muscarinic
What are the two types of adrenergic receptors?
a (alpha) and B (beta)
Describe nicotinic receptors location and effect on NT
Location=
- all ANS post ganglionic neurons
- adrenal medullary cells
- skeletal muscles (increased activity when receptor binds)
Effect of NT binding
- excitatory- increased activity of target
When Nicotinic binds to receptor it excited and creates graded then action potential
Describe muscarinic receptors location and effect on NT
location=
- all parasympathetic target organs
Effect on NT binding
- excitatory of most targets
- > increased activity
- inhibition of cardiac muscle -> decreased activity
Describe adrenergic receptor B1’s location and effect on NT binding
location
- heart
Effect on NT binding
- excitatory- increases heart rate and force of contraction
Describe adrenergic receptor B2’s location and effect on NT binding
location
- airways, blood vessels (heart, liver, skeletal muscle), digestive tract, urinary organs
Effect on NT binding
- excitatory- increased activity, i.e. relaxes smooth muscle- dilates airways and blood vessels, relaxes muscles in digestive and urinary organs
Describe adrenergic receptor a1’s location and effect on NT binding
Location
- blood vessels (except in heart, liver, skeletal muscles), all sympathetic targets
effect on NT binding
- excitatory- increased activity, i.e. constricts blood vessels and viceral organ sphincters, dilates pupils
