PHSI2005 Study Guide - Final Guide: Autonomic Nervous System, Adrenal Gland, Postganglionic Nerve Fibers
15 May 2018
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Nervous system: Sensory & autonomic pathways (3 lectures)
The Autonomic nervous system (ANS)
• Controls smooth & cardiac muscles, & glands
• Controls critical body functions:
o Blood pressure, heart rate, temperature,
digestion, elimination of wastes
• Mostly does this without awareness or attention
Divisions:
• Parasympathetic – calm your organs
o Resting & digesting
o Responsible for maintaining your body & conserving energy for later
• Sympathetic – excites your organs
o Flight or fight response
o “E division” – ruling exercise, excitement, emergency & embarrassment
o Prepares body to deal with stress
• Adrenal sympathetic
o CNS à adrenal cortex/medulla à Adrenaline à blood vessel à effector organs
*Both parts of the ANS require 2 neurons in order to work, and the 2 neurons meet in ganglia
• Ganglia – clusters of neuron cell bodies that house millions of synapses
o Preganglionic cell – neurons before ganglion
o Postganglionic cell – neurons after ganglion
Autonomic effectors
• Smooth & cardiac muscles
• Some endocrine & exocrine glands
• Some adipose tissue
Activation of autonomic pathways
Can occur in all these levels:
• Spinal cord
• Brain stem
• Hypothalamus activation
Document Summary
Nervous system: sensory & autonomic pathways (3 lectures) The autonomic nervous system (ans: controls smooth & cardiac muscles, & glands, controls critical body functions, blood pressure, heart rate, temperature, digestion, elimination of wastes, mostly does this without awareness or attention. Autonomic effectors: smooth & cardiac muscles, some endocrine & exocrine glands, some adipose tissue. Can occur in all these levels: spinal cord, brain stem, hypothalamus activation. Craniosacral (sprout from base of brain & just superior to tailbone) Relative lengths of their fibers: begin above & below where the sympathetic fibers are. Way out from spine, near or inside their effector organs (more specific/strategic signals) Closer to spinal cord (faster to send fight/flight signal) Short preganglionic; long postganglionic (long post- because close to spinal cord so longer distance to reach effector organs) **the response of target tissue to autonomic regulation is dependent on receptors expressed on target tissue.
