Autonomic Physiology 1 Flashcards
What does the autonomic nervous system exist to control?
Involuntary processes - the things you don’t think about.
Give examples of things that the autonomic nervous system controls.
Smooth muscle surrounding blood vessels, airways, bladder, gut and sex organs.
Secretions from glands.
Focussing of the eye.
Etc…
Where do afferent neurones carry impulses from and to?
From sensory receptors to the CNS.
Where do efferent neurones carry impulses from and to?
From CNS to peripheral effector organs/structures.
What does the somatic nervous system control?
Skeletal muscle control of voluntary body movements.
Describe the fibre(s) involved in sending electrical signals in the somatic nervous system.
One neurone with a very long axon which reaches the skeletal muscle.
Describe the fibre(s) involved in sending electrical signals in the autonomic nervous system.
Preganglionic fibre (small, myelinated) which passes signal to post ganglionic fibre and post-ganglionic fibre (unmyelinated) passes signal to smooth muscle/cardiac muscle.glands/GI neurones…
Compare how specialised the junctions are in the somatic nervous system and autonomic nervous system.
Somatic nervous system - very specialised NMJ: neurotransmitters are directed towards very specific area (end plate).
Autonomic nervous system - less specialised junction (can be just released in the vicinity of lots of cells)
What kind of receptors do the neurotransmitters bind to in the somatic nervous system?
Ionotropic receptors (integral channel - fast response).
What kind of receptors do the neurotransmitters bind to in the autonomic nervous system?
Metabotropic receptors (G-coupled - slower)
Comment on excitatory/inhibitory responses in the autonomic and somatic nervous system.
Neurones in the somatic nervous system always excite the target, so always cause depolarisation of end plate.
Neurones in autonomic nervous system may excite or inhibit target.
What does the sympathetic system do?
Prepares you to fight or flight.
Heart rate and blood pressure increase, airways dilate, pupils dilate, eyes focus far away, hair stands on end, mouth is dry, glycogen stores mobilised, not digesting…
What does the parasympathetic system do?
Let’s you rest and digest.
Heart rate and blood pressure decreases, pupils constrict, eyes focussed closer, hair down, laying down energy stores, digesting.
Where do the parasympathetic neurones comes from the CNS? And where do they go to?
Parasympathetic system is crania-sacral, so there is cranial outflow to head and neck and sacral to the bladder and genitals.
Cranial (III, VII, IX, X) and sacral s(2-4).
Where do the sympathetic neurones comes from the CNS? And where do they go to?
Sympathetic system is thoraco-lumbar. the ganglia lie close to the spinal cord in the sympathetic trunk (long post-ganglionic fibre).
T(1-12) and L(1-2)
Describe the post and pre-ganglionic fibres in the parasympathetic system.
Long pre-ganglionic fibre and short post-ganglionic, meaning the ganglion are in or close to their target.
Describe the post and pre-ganglionic fibres in the sympathetic system.
Ganglia close to spinal cord in sympathetic trunk (aka para-vertebral ganglia), this extends further into cervical ganglia. Normally the pre-ganglionic fibre enters the sympathetic trunk, makes synapse to long post-ganglionic fibre.
How do other post and pre-ganglionic fibres in the sympathetic system differ from normal?
Some go straight through and make synapse in the pre-vertebral (collateral) ganglia, e.g. celiac and mesenteric ganglia then the post-ganglionic fibre carries on.
How is the adrenal gland also an exception in terms of pre and post-ganglionic fibres in the sympathetic system?
Post-ganglionic cells of the adrenal medulla have no axon, but release adrenaline and noradrenaline (80%/20%) into the blood.
In the spinal cord, where are the pre-ganglionic fibres found?
White ramus (white due to myelination).
In the spinal cord, where are the post-ganglionic fibres found?
Grey ramus (grey as unmyelinated).
What two things allow mass activation?
Convergence and divergence.
What is convergence?
Many pre-ganglionic fibres synapsing onto one post-ganglionic fibre.
What is divergence?
One pre-ganglionic fibre synapsing onto several post-ganglionic fibres.
