Peripheral Nervous System (Exam 3) Flashcards
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Affectors
Somatic- skeletal muscle
Autonomic- smooth and cardiac muscle, glands, viscera
The efferent division is divided into two parts
Somatic
Autonomic
Pathway
Somatic- single neuron
Autonomic- 2 neuron chain with a synapse in between
Neurotransmitters
Somatic- Ach
Autonomic- Ach, epinephrine, neuroepinephrine
Neurotransmitter effect on target cell
Somatic- always excitatory
Autonomic- excitatory or inhibitory
Cholinergic fibersq
Fibers that release Ach
Adrenerhic fibers
Neurons that release epinephrine and neuroepinephrine
Cholinergic receptors
Bind and respond to Ach
Nicotinic 1&2
Muscarinic 1,2,&3
Adrenergic receptors
Binds and respond to epinephrine and neuroepinephrine
Alpha 1&2
Beta 1&2
Preganglionic fibers
Neuron whose cell body lies in the CNS
Releases NT that across a Neuro-neuronal synapse and binds with a second neuron
Postganglionic fiber
Neuron whose cell body lies in the PNS
Binds to the NT released from the postganglionic fiber
Axon extends to the effector organ
Releases NT that bind to the effector organ
Autonomic NS is divided into two parts
Parasympathetic and sympathetic
Dual innervation
Most viscera is innervated by both the parasympathetic and the sympathetic NS
Autonomic tone
One division is exhibiting more tone depending on what the body needs
Parasympathetic and sympathetic ______ each other and _______ are active all the time
Oppose
Both
Function of the parasympathetic NS
Rest and digest
Vegetative and Maintance activities
Conservation of ATP
Ex. Decrease HR, decrease BP, increase digestive function
Function of the sympathetic NS
Fight or flight
Prepares body to deal with an energetic situation
Uses ATP
Ex. Increase HR, increase BP, decrease digestive function
Origin sites of preganglionic fibers
Sympathetic- thoracolumbar region of the spinal cord (T1-L2)
Parasympathetic- cranial and spinal nerves
Occulomotor (3)
Smooth muscle of the eye that influences pupil size and eyeball movement
Facial (7)
Nasal glands
Lacrimal glands
Submandibular and sublingual salivary glands
Glassopharyngeal (9)
Parotid salivary gland
Vagus (10)
90% of the parasympathetic supply Branches into the Cardiac plexus Pulmonary plexus Esophageal plexus Descending aortic plexus
Cardiac plexus
Innervates the heart
Pulmonary plexus
Innervates the lungs and bronchi
Esophageal plexus
Innervates the esophagus
Descending aortic plexus
Innervates most abdominal viscera
Sacral region of the spinal cord Innervates:
Distal half of the large intestine
Urinary bladder
Reproductive organs
Location of ganglia (origin of postganglionic fiber)
Sympathetic- sympathetic ganglionchain
Collateral ganglion
Adrenal medulla
Parasympathetic- terminal ganglion
Sympathetic ganglionchainq
Close to the spinal cord
Collateral ganglion
Midway between the spinal cord and the effector organ
Adrenal medulla
Internal portion of the adrenal gland
Some preganglionic fibers synapse
With the adrenal medulla
Preganglionic sympathetic fiber releases Ach which binds to N1 receptors on medullary tissue
This causes a release of epinephrine and neuroepinephrine into the blood stream
(system wide sympathetic response)
Terminal ganglion
Close to the effector organ
Nicotinic receptor
Receptor stimulation by Ach is always excitatory
N1
N2
N2
On sarcolemma of skeletal tissue (depolarization)
N1
On all postganglionic cell bodies (at all ganglia in ANS)
On adrenal medulla
Muscatinic receptors
Receptor stimulation by ch can result in an excitatory or inhibitory response depending on the receptor and the target organ
M1
M2
M3
M1
Located on neural tissue
Excitatory
M2
Located on heart
Inhibitory (decrease muscle contraction)
M3
Located on smooth muscle and glands
Excitatory
Alpha
Stimulation is generally excitatory
Except alpha2 on gut muscle
Alpha1
Alpha2
Beta
Stimulation is generally inhibitory
Except beta1 on the heart
Beta1
Beta2
Eye
P- pupil constriction via contraction of the circular muscle of the iris (M3)
S- pupil dilation via the contraction of the radial muscle of the iris (Alpha1)
Digestive glands
P- increase in secretory activity (M3)
S- decrease in secretory activity (Beta2)
Digestive tract smooth muscle
P- increase in motility (M3)
S- decrease in motility (Alpha2, Beta2)
Increase contraction of sphinctors (Alpha1)
Sphinctor
Cuff of smooth muscle between one organ and the next
Heart
P- decrease in HR (M2)
S- increase in HR (Beta1)
Liver
P- no innervation
S- glycogen breakdown (Beta2)
Blood vessel smooth muscle
P- no innervation
BV serving the external genetalia (M3)
S- blood vessel vaso-constriction (Alpha1)
Respiratory system
P- contraction of smooth muscle surrounding the bronchioles (M3)
S- relaxation of the smooth muscle surrounding the bronchioles (Beta2)