Autonomic Physiology COPY Flashcards
What branch of the ANS is involved in fight or flight?
sympathetic
Where do the sympathetic fibres arise from in the spinal column?
T1-L2(3) (Thoracolumbar)
What part of the spinal cord do the sympathetic fibres arise from?
lateral horns
Compare the length of the preganglionic and postganglionic fibres in the sympathetic system.
Preganglionic fibres are short. Postganglionic fibres are long.
Where do sympathetic fibres emerge from the spinal cord?
In the ventral rami via a white ramus communicans (preganglionic fibre)
What structure allows for transmission of sympathetic impulses throughout the body and not just between levels T1-L2?
The sympathetic chain
How is the sympathetic chain arranged?
Paravertebrally
What levels does the sympathetic chain span?
C1- Coccygeal 1
What ability of the sympathetic system results in the mass response of the body to it?
The ability of the impulses to run up and down the sympathetic chain and synapse in different areas
The sympathetic system has 3 options for mechanisms by which the fibres can synapse. Describe them.
- can synapse in a chain ganglion AT THE SAME LEVEL before exiting
- ascend and descend within the sympathetic chain before synapsing at a DIFFERENT LEVEL and exiting
- pass straight through chain and SYNAPSE ELSEWHERE
What synapsing mechanism of the sympathetic fibres will NOT be used concerning supply to the skin and body wall?
passing straight through chain and synapsing elsewhere
What body structures can make use of all 3 sympathetic synapsing mechanisms?
supply to the viscera
How are the heart and lungs supplied by the sympathetic system?
preganglionic fibres synapse in paravertebral ganglion but do not leave via grey ramus communicans. Instead pass straight through to supply the heart or lungs.
How are the abdominal viscera supplied by the sympathetic system?
preganglionic fibres DON’T synapse in the paravertebral chain but instead in a pre-aortic ganglion (prevertebral) and then continue as a postganglionic fibre within the organ
What 2 qualities characterise a splanchnic nerve?
- do not re-enter spinal nerve
2. only supply thoracic or abdominopelvic viscera
Where do the thoracic splanchnic nerves arise from?
T1-T4
Where do the abdominal splanchnic nerves arise from?
T5-L2(3)
What body structure must the T5-T12 splanchnic pass through to reach the abdominal viscera?
the diaphragm
Which ANS does general sensory information from the viscera run with?
parasympathetic fibres
Which ANS is the main conductor of pain impulses from the viscera?
sympathetic
Which ANS conducts pain impulses from PELVIC viscera?
parasympathetic (as well as sympathetic)
What ANS is involved with resting and digesting?
parasympathetic
Where do the parasympathetic fibres arise from?
cranial nerves C3,7,9 and 10 and S2-4 (craniosacral)
What are the parasympathetic fibres arising from S2-S4 also commonly referred to as?
pelvic splanchnic nerves
Compare the length of preganglionic fibres and postganglionic fibres in the parasympathetic system.
Long preganglionic fibres. Short postganglionic fibres.
What is the pelvic (inferior hypogastric) plexus?
Converging of sympathetic and S2-S4 parasympathetic fibres as a paired mixed network.
How do the sympathetic fibres synapse in relation to the pelvic plexus?
synapse in plexus before supplying pelvic viscera
How do the parasympathetic fibres synapse in relation to the pelvic plexus?
run through plexus and synapse in ganglia within target organ walls
Describe the ‘pathway’ of the parasympathetic fibres.
Preganglionic fibres run bilaterally run through the lumbosacral plexus in the cauda equina to the sacral foramina at levels S2-S4
Then exit via foramina at S2-S4 and run through pelvic plexus to synapse in parasympathetic ganglion near or in target organ. Postganglionic fibres then supply organ.
What neurotransmitter is released from sympathetic preganglionic nerve fibres?
acetylcholine
What neurotransmitter is released from the sympathetic postganglionic fibre?
noradrenaline
What is the exception to the sympathetic system’s neurotransmitter release rule?
preganglionic fibre in kidney medulla enough to stimulate release of the HORMONE noradrenaline which is then carried in blood to produce response
What receptors does noradrenaline act on in the sympathetic nervous system?
alpha and beta receptors
As a rule, what effect will activation of alpha 1 receptors have on smooth muscle?
contraction
As a rule, what effect will activation of beta 2 receptors have on smooth muscle?
relaxation
Smooth muscle tissue in skeletal muscle has lots of what kind of receptor?
beta receptors (presumably to allow for quick dilation of blood vessels to allow maximum blood flow)
The gut has many of what kind of sympathetic receptor?
alpha receptors (peristalsis)
How does the sympathetic system cause the pupil to dilate?
by causing radial muscle contraction by activating alpha 1 receptors
How does the sympathetic system cause the eyes to focus far away?
by activating beta 2 receptors to relax ciliary muscle
How does the sympathetic system increase the heart rate?
by activating beta 1 receptors on pacemaker cells
How does the sympathetic system increase the strength of contraction of the heart?
by activating beta 1 receptors on myocytes
How does the sympathetic system cause dilation of the airways?
by activating beta 2 on the smooth muscle of airways
How does the sympathetic system cause contraction of the blood vessels? Why would it want to do this?
by activating alpha 1 receptors. It will decrease blood flow to a particular area but increase it elsewhere where it is needed more for the fight/flight response
How does the sympathetic system cause relaxation of blood vessels?
by activating beta 2 receptors - increases blood flow
How does the sympathetic system aid the reproductive system in men?
activation of alpha 1 receptors on smooth muscle of urethra causes contraction causing ejaculation
How does the sympathetic system reduce pressure in the bladder?
activation of beta 2 receptors in the bladder wall causing relaxation
How does the sympathetic system prevent you from peeing?
activation of alpha 1 receptors on smooth muscle of sphincter muscle
How does the sympathetic system affect energy stores?
activates alpha or beta receptors on liver cells to increase gluconeogenesis
What neurotransmitter is released from the parasympathetic postsynaptic fibre?
acetylcholine
What type of receptor does the parasympathetic postganglionic fibre’s neurotransmitter act on?
muscarinic
How does the parasympathetic system affect the eyes?
pupil constricts - radial muscles
eye focusses close up - ciliary muscles
How does the parasympathetic system affect the heart?
decreases heart rate by activating muscarinic receptors on pacemaker cells
little effect on force of contraction
How does the parasympathetic system affect the lungs?
activating the muscarinic receptors causes constriction of the airways by contraction
What effect does the parasympathetic system have on blood vessels?
very little effect
What effect does the parasympathetic system have on the digestive system?
activates muscarinic receptors which increase enzyme secretion from pancreas
What effect does the parasympathetic system have on the energy stores?
little effect
What effect does the parasympathetic system have on the salivary glands?
activating muscarinic receptors stimulates profuse watery secretion
What effect does the parasympathetic system have on the bladder?
activating muscarinic receptors on bladder wall - contracts and increases pressure
‘’ ‘’ on sphincter muscles - sphincter muscle relaxes causing urination
What effect does the parasympathetic system have on the reproductive system in men?
activates muscarinic receptors on smooth muscle of corpus cavernous causes relaxation of smooth muscle - the erection
