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Human Physio Topic 8


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What are the two parts of the autonomic system?
Sympathetic and parasympathetic
What is the definition of Efferent Divison?
a communication link by which the CNS controls activities of effector organs (e.g., muscles, organs, glands, etc.)
Autonomic is a/an _______ branch vs Somatic is a/an _______ branch.
involuntary; voluntary
What are effector organs?
-receive the signal from CNS -muscles, glands, adipose tissue
What does our somatic system control?
skeletal muscles
What is the Autonomic NS Primary Function?
to regulate the function of effector organs in order to maintain homeostasis
What is the adrenal medulla?
a modified sympatheic ganglion that secretes hormones into blood when stimulated. -in Sympathetic only
Where does the sympathetic NS originate?
tharacic (chest) & lumbar (abdominal) regions of spinal cord
In the Autonomic NS, what is the common structure for both sympathetic and parasympathetic NS?
1. Every pathway has 2 neuron chains 2. Cell body of 1st neuron lies w/in CNS 3. Axon synapses w/ cell body of 2nd neuron in chain in a ganglion 4. Axon of 2nd neuron innervates the effector organ
What are the characteristics of the Parasympathetic only?
-routine housekeeping -most active during rest -originate in brain (cranial) and sacral (pelvic) areas of CNS -Ganglia close to effector organs
Neurotransmitters: Sympathetic
1. 1st neuron releases Acetylcholine 2. 2nd neuron releases norepinephrine 3. adrenal medulla releases epinephrine into blood -SO: onto effector organs --> releases norepinephrine & epinephrine
Neurotransmitters: Parasympathetic
1. 1st neuron releases ACh 2. 2nd neuron releases ACh -SO: onto effector organs --> releases ACh
Response of effector organs to sympathetic and parasympathetic depend on what?
effector organ & its receptors & neurotransmitters
When the body is stressed, what are the relative contributions of the sympathetic and parasympathetic nervous systems?
Both are active but the sympathetic is dominant.
Acetylcholine receptors
-located on 2nd neuron -on membrane of effector organs
When the sympathetic NS dominates what happens?
"Fight or Flight" response -blood vessels constrict (alpha binding to norepin.) -heart dilated (beta-2) -dilate blood vessels to skeletal muscles (beta 2) -Increase heart rate and force of contraction (Beta 1) -Airways dilate (Beta 2) -Liver releases glucose (B2) -Pupils dilate (alpha)
What happens when the Parasympathetic is Dominant?
"Rest & Digest" "housekeeping" functions (digestion, etc) -decreases heart rate -increase GI motility -Stimulate GI secretions -Relax GI sphincters -Contract airways to lungs -Pupils constrict -Eye muscles contract for near vision
Lou Gehrig's Disease
-Progressive disease -motor neurons die -brain and spinal cord affected -APs randomly fire and cause uncontrollable visible contractions -voluntary muscle control affected -Early symptoms: muscle weakness -Later stages: paralysis -"mind" unaffected -2 per 100,000 people -throughout world -10% family history -Causes of sporadic form not known -50% of patients die w/in 2 yr of diagnosis -Lou Gehrig, Stephen Hawking

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