Autonomic nervous system

• What are the two branches of the Autonomic Nervous System?

  Sympathetic and Parasympathetic

  
• What is the primary function of the sympathetic branch of the Autonomic Nervous System?

  It is responsible for the fight or flight response
• What is the primary function of the parasympathetic branch of the Autonomic Nervous System?

  It is responsible for the rest and digest response
• What does homeostasis refer to in the context of the Autonomic Nervous System?

  It is the regulation of the internal environment of the body to maintain a relatively constant condition
• What are some functions regulated by the Autonomic Nervous System?

  Contraction and relaxation of smooth muscle, heartbeat, exocrine and endocrine secretions, energy metabolism
• What is meant by antagonistic control in the Autonomic Nervous System?

  Branches of the ANS have opposing effects in target tissue

  
• What is tonic control in the context of the Autonomic Nervous System?

  It refers to a variable response depending on the level of input
• How do different receptor populations affect tissue responses in the Autonomic Nervous System?

  They lead to variable tissue responses
• What is the main neurotransmitter of the Autonomic ganglia?

  Acetylcholine (ACh)

  
• What type of receptors does acetylcholine act on in the Autonomic ganglia?

  Nicotinic ACh receptors
• What do chromaffin cells in the adrenal medulla secrete?

  Adrenaline (epinephrine)
• What type of neurons secrete alternative transmitters in the Autonomic Nervous System?

  Non-adrenergic, non-cholinergic (NANC) neurons
• Where do sympathetic pathways originate in the spinal cord?

  Thoracic and lumbar regions
• What neurotransmitter is usually associated with sympathetic pathways?

  Noradrenaline (NA)

  
• Where do parasympathetic pathways originate in the spinal cord?

  Brain stem and sacral region
• What neurotransmitter is associated with parasympathetic pathways?

  Acetylcholine (ACh)

  
• What type of receptors do parasympathetic responses mediate?

  Muscarinic ACh receptors
• How is acetylcholine (ACh) synthesized?

  From choline via the action of choline acetyltransferase (CAT)
• How is acetylcholine (ACh) removed from the neuroeffector junction?

  By acetylcholinesterase (AChE)
• How is noradrenaline (norepinephrine) synthesized?

  From tyrosine via the action of several enzymes

  
• How is noradrenaline (norepinephrine) removed from the neuroeffector junction?

  By Uptake 1 and Uptake 2

  
• What happens to cytosolic noradrenaline (NA)?

  It is metabolised by monoamine oxidase (MAO)
• What neurotransmitter is released along the preganglionic fibre in the parasympathetic pathway?

  ACh
• What type of receptors does ACh act on in the parasympathetic pathway?

  Nicotinic receptors
• What is the effect of ACh on the postganglionic fibre in the parasympathetic pathway?

  It stimulates the postganglionic fibre
• What type of receptors does ACh act on in the postganglionic fibre of the parasympathetic pathway?

  Muscarinic receptors
• How does the length of the sympathetic pathway compare to the parasympathetic pathway?

  It is shorter
• What neurotransmitter is released from the preganglionic fibre in the sympathetic pathway?

  ACh
• What type of receptors does ACh act on in the sympathetic pathway?

  Nicotinic receptors
• What neurotransmitter is released at the postganglionic receptors in the sympathetic pathway?

  Noradrenaline
• What are the exceptions in the sympathetic pathway regarding neurotransmitter release?

  • On sweat glands: ACh is released on the postganglionic fibre and acts on muscarinic receptors.
  • On adrenal medulla: ACh is released on a long postganglionic fibre and acts on nicotinic receptors.