4 CVS Flashcards
(22 cards)
What define parasympathetic and sympathetic systems?
The origin of the presynaptic nerve.
- cranial and sacral: parasympathetic
- thoracic and lumbar: sympathetic
sympathetic activity in increased when…
stressed
The effect of the sympathetic system on the pupil of the eye is…
dilation (if fighting need to see really well)
Which receptor mediates the effect of the sympathetic system on the pupil?
a1 adrenoceptor
What effect does the parasympathetic system have on the pupil of the eye?
cintraction
Which receptor mediates the effect of the parasympathetic system on the pupil?
M3 muscarinic
Contraction of which muscle is responsible for pupil dilation?
radial muscle contraction
Contraction of which muscle is responsible for pupil contraction?
sphincter muscle contraction
Which receptors mediate the effect of the sympathetic system on the lungs?
b2 adrenoceptors
Which receptors mediate the effect of the parasympathetic system on the lungs?
M3 muscarinic receptors
which receptors mediate the effect of the sympathetic system on the heart?
b1 adrenoceptors
which receptor mediates the effect of the parasympathetic the heart?
M2 muscarinic
Which receptors mediate the effect of the symapthetic system on the sweat glands?
in the case of localised secretion (eg. palms)?
a1 adrenoceptors
Which receptors mediate the effect of the symapthetic system on the sweat glands in the case of generalosed secretion?
M3 muscarinic
What effect does the parasympathetic system have on the sweat glands?
NONE!
Is an increase in sympathetic drive generalised to alltissues or are they dissociated?
They are dissociated as far as sympathetic drive is concerned.
eg. sympathetic activity to the heart can be increased without increasing activity to GI tract
Ehich 3 main activities does the autonomic nervous system control?
- smooth muscle (vacular and visceral)
- Exocrine secretion
- rate and force of contraction of the heart
Does the ANS initiate electrical activity in the heart?
NO, SA node. ells spontaneously depolarise..
a dennervated heqrt still bests. but faster.
If ANS effect on heart was cut off what would happen?
the heart would continue to contract but at a faster rate. Why? because at rest the heart is normally under vagal control.
What does the ANS exert control over in the heart?
- heart rate
- force of contraction
- and a parasympathetic tone at rest lower the heart beat. ie. if heart was dennervated, it would beat faster at about 100 bpm
Where does the vagus nerve synapse with the postganglionic fibers?
On epicardial surface or within the walls of the heart. so the postganglionic nerve is very short.
Which parasympathetic pregsnglionic nerve innervates the heart? name and number
10th cranial nerve. called vagus
