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What are the two systems of the Efferent System? What do they innervate?
- 1: Autonomic (smooth muscle, cardiac muscle, glands)
- 2: Somatic (skeletal muscle)
What are the two systems of the autonomic nervous system?
- 1) Parasympathetic Nervous System
- 2) Sympathetic Nervous System
Is the ANS involuntary or voluntary control? Somatic?
- ANS: involuntary
- Somatic: voluntary
Describe the neural pathway of a neuron in the somatic pathway
- CNS (ventral root) -->
- myelinated axon -->
- nicotinic receptor on skeletal muscle
A somatic nerve on a skeletal muscle is excitatory/inhibitory or both?
What is the primary neurotransmitter in the somatic system?
Describe the neural pathway of a ANS-SNS neuron
- T1-L3 -->
- short preganglionic myelinated axon -->
- nicotinic receptor @ ganglion -->
- longer demyelinated postganglionic axon -->
- adrenergic effector
Describe the neural pathway of a ANS-PNS neuron
- CN 3,7,9,10, SN 2,3,4 -->
- long preganglionic myelincated axon -->
- nicotinic receptor @ ganglion -->
- shorter demyelinated postganglionic axon -->
- muscarinic receptor on effector
The autonomic nervous system produces an excitatory/inhibitory/or both response on the effector?
Both - depending on whether the stimulation is sympathetic or parasympathetic
What are the primary neurotransmitters of the ANS?
Acetylecholine and Norepinephrine
What are the 3 divisions of the ANS?
Sympathetic, Parasympathetic, Enteric
What is the highest level of ANS integration?
Hypothalamic nuclei are responsible for:
body response to stress, blood pressure control, temp regulation
Medulla and pons responsible for:
- hemodynamic and ventilatory control
- integrating and maintaining the automaticity of ventilation
What is the difference in terms of quality of response of the SNS and PNS?
- SNS = mass reflex responses
- PNS = much more limited response
What are the 3 different types of ganglia?
- 1) 22 paired vertebral column
- 2) unpaired prevertebral ganglia
- 3) terminal ganglia
Describe the innervation of the adrenal gland
- Spinal cord -->
- preganglionic myelinated axon -->
- SNS stimulation of nicotinic receptor -->
- intracellular transition to post ganglionic -->
- release of Epinepherine (80%) and Norepinephrine AS HORMONES
What is the difference between NE as a neurotransmitter and NE as a hormone?
NE as a hormone is released directly into the blood stream - prolonged response d/t the time need for the metabolism by COMT (catecholamine-o-methyltransferase)
What are the different types of adrenergic receptors?
a1, a2, b1, b2
What does stimulation of an a2 receptor cause?
- Stimulation on the a2 receptor of a presynaptic cell -->
- activation of negative feedback system -->
- decreased NE released
Where are beta 1 receptors located?
heart and fat cells
What is beta 1 activation cause in the heart?
increased HR, increased contractility, increased conduction velocity
Where all are Beta 2 receptors located?
- blood vessels (esp coronary and skeletal arteries)
What does stimulation of Beta 2 do to the blood vessels?
What does stimulation of beta 2 do to the bronchioles?
What does stimulation of beta 2 do to the uterus?
What does stimulation of beta 2 do to the liver?
Where are alpha 1 receptors located?
- blood vessels
- intestine and bladder
What does alpha 1 activation do to blood vessels?
What does alpha 1 activation do to the pancreas?
inhibition of insulin secretion
Where are alpha 2 receptors located?
- postganglionic presynaptic sympathetic nerve ending
What does activation of alpha 2 in the CNS cause?
increase in potassium conductance --> hyper polarization --> sedation
What does activation of alpha 2 on platelets cause?
Describe the steps to the synthesis of Norepinephrine
- 1) tyrosine is actively transported in to the adrenergic presynaptic nerve terminal cytoplasm
- 2) tyrosine is converted into dopamine (2 steps in the cytoplasm)
- 3) Dopamine is transported into the vesicles
- 4) Dopamine is B-hydroxylated to NE
Describe the metabolism of Norepinephrine (3 diff ways)
- 1) Reuptake into the presynaptic terminal for reuse (primary mechanism)
- 2) metabolism by COMT (in blood) and MAO (in presynaptic nerve terminal)
- 3) Diffusion away from synaptic cleft
What enzyme converts NE to E?
PNM - Phenylethanolamine-N-methyltransferase
How does cortisol affect PNM?
cortisol enhances PNM
Which nerve controls 75% of the PNS?
CN III innervates ______
CN VII innervates the _______
lacrimal, nasal, and submaxillary glands
CN IX innervates the ___
CN X innervates the _____
thoracic and abdominal regions of the body
Where does the synthesis of acetylcholine occur?
presynaptic cytoplasm of preganglionic and postganglionic parasympathetic nerve endings
Describe the synthesis of Ach
- In the presynaptic cytoplasm
- Acetyl CoA + Choline via CAT
- Acetyl CoA is synthesized in mitochondria
- Choline enters cell from ECF via active transport
What are the 2 exceptions to the Sympathetic Nervous System (as far as pathway)? how are they different?
1) Sympatho-adrenal branch: preganglionic cholinergic nerve directly innervates the medulla --> release of Epi and NE as hormones
2) Sympatho-cholinergic: cholinergic (as opposed to adrenergic)