Introduction to the ANS Flashcards
What does the somatic nervous system control?
Skeletal muscle (including diaphragm and respiratory muscle)
What does the autonomic nervous system control?
Smooth, and cardiac muscle, exocrine glands, metabolism, host defence=
What does the neuroendocrine system control?
Growth, metabolism, reproduction, development, salt & water defence
Which part of the ANS controls pupil dilation and constriction?
Dilation - Sympathetic NS
Constriction - Parasympathetic NS
Which nerve innervates the stomach that controls digestion?
Vagus
Describes the effects baroreceptors have when stimulated?
Stimulatory effect on parasympathetic nerves which activate an inhibitory nerve to the heart - decreases HR
Inhibitory effect on the sympathetic nerves - sympathetic stimulation increases HR, it has an effect on the heart and the arterioles and veins.
The arterioles and veins are controlled by sympathetic nerves NEVER by parasympathetic. Arterioles; Constriction and dilation
What is the BP proportional to?
Baroreceptor firing rate
What NS dominates the heart?
Parasympathetic
Draw the diagram for the control of HR with the nerves.
See diagram
See diagram with principle target and functions of the ANS
See diagram
What controls the ciliary muscle?
Parasympathetic NS
What nerves supply the trachea and bronchioles?
Parasympathetic nerves, no sympathetic. There are still sympathetic effects cause Adrenaline is delivered to the lungs.
What effect does parasympathetic innervation have on the lungs?
Constriction
What nerves supply blood vessels and what do they do?
Sympathetic - dilate and constrict
Draw a diagram for the neurotransmitters and receptors in the ANS
See diagram - need to know which neurotransmitter is released from which nerve in the PNS and the SNS as well as receptors
How can the PNS be described as?
Discrete and localised - 1:1 pre vs post ganglionic neurone
How can the SNS be described as?
Coordinated response and divergent - 1:20 pre vs post ganglionic neurone
Where does the PNS and SNS originate from?
PNS: cranial + sacral
SNS: Thoracic + lumbar
Where does sensory information of the gut go to?
Information is relayed to submucosal and myenteric plexus via interneurones
What are the receptors are the targets for ACh?
Nicotinic and Muscarinic receptors
Describe the Nicotinic receptor
1) Found in all autonomic ganglia - they transfer stimulus from the preganglionic to the post ganglionic neurone
2) Type 1 - iontropic. They are ion channel linked
3) FAST
4) Activated by ACh/nicotine and blocked by hexamethonium and trimetaphan
Describe the Muscarinic receptor
1) Found on all target organs innervated by post ganglionic parasympathetic nerves
2) Type 2 - G-protein coupled
3) Slower than nicotinic
4) Activated by ACh/Muscarine and blocked by atropine and hyoscine
What one exception has muscarinic receptors?
Sweat glands - sympathetic innervation but releases ACh so activates muscarinic receptors on sweat glands
Where can muscarinic receptors be found?
Found on any target organ where the post ganglionic neurone releases ACh
Which ANS tends to increase urinary frequency?
Parasympathetic (rest and digest)
What effect would blockage of nicotinic ACh receptors have on heart rate at rest and during exercise?
Rest: HR increases
Exercise: HR lower than expected
This question requires you to think about which effect is dominant when. Important
What are the sub-types of Muscarinic receptors?
M1 - Neural M2 - Cardiac M3 - Exocrine and Smooth muscle M4 - Periphery M5 - Striatal dopamine release
What are the sub-types of Adrenoreceptors?
a1
a2
b1
b2
Describe the adrenoreceptors
1) These receptors are found on the end of the sympathetic nervous system
2) There are 4 subtypes
3) G-protein coupled
4) Stimulated by NA and by A produced by the adrenal medulla
What blocks nictoinic receptors?
Hexamethonium
What blocks muscarinic receptors?
Atropine
What NS controls the vascular system?
SNS
a1 - constricts
b2 - dilates
Describe the synthesis, release and metabolism of ACh
See diagram - all reactants, products and enzymes must be known
Describe the synthesis, release, reuptake and metabolism or noradrenaline
See diagram - all reactants, products and enzymes must be known
What receptors does NA bind to?
Adrenoreceptors
