ANS Flashcards
What is the ANS?
→ sub-division of the peripheral nervous system that is NOT under conscious control
→ controls many of the body’s organ systems and homeostatic mechanisms
→ effects are involuntary i.e. they are reflex responses to visceral stimuli
How is the ANS regulated?
Hypothalamus
What does the ANS control?
controls non-skeletal peripheral function
e.g. Cardiac muscle, smooth muscle, Internal organs, skin
What are the 3 branches of the ANS?
→ sympathetic
→ parasympathetic
→ enteric
What are the sympathetic + parasympathetic systems often called?
→ SYMPATHETIC = the ‘fight or flight’ system
→ PARASYMPATHETIC = the ‘rest and digest’ system
How do the parasympathetic + sympathetic systems generally work?
→ often innervate the same tissues + have antagonistic effects
→ react to sensory information received in the integrating centre
What is the exception to the “innervation of same tissue” concept?
SMS controls blood vessel tone - both constriction + dilation
What is the para/sympathetic effect on the heart?
Sympathetic = increases heart rate + contractility Parasympathetic = decreases heart rate + contractility
What is the para/sympathetic effect on the pupil?
Sympathetic = dilation Parasympathetic = constriction
What is the para/sympathetic effect on the bladder?
Sympathetic = relaxation Parasympathetic = contraction
What is the para/sympathetic effect on the lungs?
Sympathetic = dilation Parasympathetic = constriction
What is the para/sympathetic effect on the GIT?
Sympathetic = decrease motility + secretions Parasympathetic = increase motility + secretions
What is the para/sympathetic effect on the liver?
Sympathetic = increased glucose release Parasympathetic = increased bile release
What is the location of the visceral motor motor nuclei?
Hypothalamus
Where do the visceral motor neurones project?
to the brainstem or the spinal cord where they synapse with autonomic neurones
What do autonomic neurones generally consist of?
a pre-ganglionic + a post-ganglionic neurone
What kind of ganglions and pre + post ganglionic neurones are present in the parasympathetic nervous system?
→ Long pre-ganglionic fibres
→ Ganglions close to or within effector tissues
→ Short post-ganglionic fibres
What kind of ganglions and pre + post ganglionic neurones are present in the sympathetic nervous system?
→ Short pre-ganglionic fibres
→ Ganglions close to or within effector tissues
→ Long post-ganglionic fibres
What is the one exception to the 2 neurone arrangement in the ANS?
Adrenal gland
What neurotransmitter is released at most of the autonomic synapses? What is the exception?
Acetylcholine, but noradrenaline at the sympathetic post-ganglionic
What does the adrenal gland secrete?
adrenaline (and some noradrenaline) into the bloodstream, NOT a synapse.
