Autonomic Nervous System Flashcards
Somatic Nervous System
Innervates skeletal muscle and receives sensory information from senses
Somatic Nervous System Components
CNS and PNS Components
Autonomic Nervous System
Innervates the viscera (organs). Functions without you telling them to.
Autonomic Nervous System Description
Influences smooth muscle, cardiac muscle, and glands of skin and viscera
CNS and PNS Components
Most cranial and spinal nerve contain both somatic and autonomic axons
Hierarchy of the A.N.S. Component
Hypothalamus
Hierarchy of the A.N.S.
Oversees ALL ANS activity
“Middle Management” are the autonomic nervous centers in the brainstem
The “Ordinary Workers” are the preganglionic and postganglionic neurons
Somatic Motor (CNS or PNS)
CNS
Somatic Motor
Uses two neurons to go from spinal cord to skeletal muscle
Autonomic Motor
It uses three neurons to go from the spinal cord to the target tissue
Autonomic Motor - 1st Neuron is Preganglionic Neuron
Cell body located i CNS (Brain or Spinal Cord)
The axon will synapse with the postganglionic neuron
Autonomic Motor - 2nd Neuron is a Postganglionic (Ganglionic) Neuron
Cell body located in an autonomic ganglion
This axon will connect to the target tissue (effector)
Why does the autonomic nervous system use two neurons in a chain to an organ?
(Preganglionic (Chicago to Indy) vs Postgang (Chicago to Miami)). ANS has limited number of resource neurons, by using two resource chain, information is able to congregate and separate efficiently.
Divisons of the ANS
Sympathetic Division
Parasympathetic Divison
Sympathetic Division
Originates in lateral horns of T1-L2 regions of Spinal cord
“Emergency” situations; SD in charge of this
“Fight of Flight” Response
“Mass Activation” Effect
Parasympathetic Division
Some cranial nerves and parts of the sacral region of the spinal cord
Maintains a homeostatic environment (Bring body back to normal)
“Rest and Digest” Response
Parasympathetic activity is usually discrete and localized
Parasympathetic Divisions - Location and Characteristics
Cranial Components are part of CN III, VII, IX, and X
Sacral Components from S2-S4 segments of the spinal cord
Pelvic Splanchnic Nerves –> Carry Parasympathetic
Parasympathetic Divisions - Pathway for Axons
Cell bodies of preganglionic motor neurons located in parts of certain cranial nerves, or in the sacral part of the spinal cord
Preganglionic axons synapse in postganglionic which are located close to or on the organ being innervated
Parasympatthetic Postganglionic Axons travel from the terminal ganglia to the target organ
Sympathetic Division (1)
Cell bodies of preganglionic motor neurons in lateral horns of T1-L2 segments of spinal cord
*The preganglionic axons exit to spinal nerve, and then go into the
Sympathetic Division - White Ramus
Runs from spinal nerve to sympathetic trunk
Sympathetic Division - Sympathetic Trunk
Long chains of axons on either side of vertebral column
Sympathetic trunk (paravertebral) ganglia
*Only Entrance
Sympathetic Division - Gray Rami
Runs from sympathetic trunk TO a spinal nerve
Sympathetic posthanglionic axons
*Exits Posteriorly
Sympathetic Division - Splanchnic Nerves
Preganglionic axons that do not synapse in the sympathetic trunk ganglia
- From trunk to other side
- Exits Anterorilly
Sympathetic Division - Prevertebral Ganglia
Splanchnic nerves synapse here
Located in front of the vertebral column
Sympathetic Division - Sympathetic Postganglionic Axons
Travel directly to target organ
Pathways for preganglionic sympathetic axons (1)
All preganglionic axons enter the sympathetic trunk via the white ramus
*anterior roots à spinal nerve à white rami à sympathetic trunk ganglia
Pathways for preganglionic sympathetic axons (2)
some synapse in the sympathetic trunk and leave through the gray rami to spinal nerves (Skin)
Pathways for preganglionic sympathetic axons (3)
some synapse in the sympathetic trunk and leave anteriorly to go to thoracic organs (Heart and Lungs)
Pathways for preganglionic sympathetic axons (4)
some preganglionic axons leave sympathetic trunk as splanchnic nerves, go to prevertebral ganglia to synapse (Abdominal Organs)
How does the parotid gland know when to secrete salvia?
Rest and Digest, CN IX
How about other salivary glands?
CN VII, has to be autonomic
Where does CN X take parasympathetic information to?
Down to the rest of the body