Section 2 Flashcards
What is the ANS a subdivision of?
the PNS
How can the ANS be further subdivided?
sympathetic and parasympathetic
State the overview of the PNS.
-PNS: divided into sensory (afferent) and motor (efferent)
-Motor (efferent): divided into somatic and autonomic
-Autonomic: divided into sympathetic and parasympathetic
What does ANS stand for?
autonomic nervous system (ANS)
What is the ANS known as, and what is it responsible for?
-visceral motor system
-responsible for transmitting involuntary signals from the CNS to smooth muscles, cardiac muscle, and glands
what type of neuron pathway is the ANS?
two neuron pathway. which means that between the CNS and any target organ, there are 2 neurons
What is the preganglionic fibre?
has its cell body within the CNS. The axon enters into the PNS and travels to the autonomic ganglion
What is the autonomic ganglion?
where the preganglion and postganglion neurons meet and communicate. It is located in the PNS
What is the postganglion fibre?
is the entirety in the PNS. Its cell body is in the autonomic ganglion, while its axon travels to the target organ
what are differences between the sympathetic and parasympathetic nervous system?
sympathetic:
-spinal cord segment T1-L2 (also called thoracolumbar division)
-widely distributed to many parts of the body
Parasympathetic:
-brainstem and spinal cord segment S2-S4 (also called craniosacral division)
-more limited distribution to target organs, with localized effect
what is another way in which the sympathetic and parasympathetic systems differ?
how their associated nerves travel from the CNS to the target organs
Describe the sympathetic pathways.
-the nerves of the sympathetic nervous system exit from the spinal cord to supply innervation to the body
1) Lateral Horn of the Spinal Cord: sympathetic preganglionic axons leave the lateral horn of the spinal cord, along with the somatic motor axons, to form the anterior root
2) Sympathetic Trunk: preganglionic axons pass through the spinal nerve to the sympathetic trunk, a structure lateral to the spinal cord on either side. the sympathetic trunk provides a pathway for the sympathetic fibres to travel through the body, both superiorly and inferiorly
3) Ganglion: preganglionic neurons synapse with postganglionic neurons in the ganglia
4: Effector Organ: postganglionic axons leave the sympathetic trunk to enter the spinal nerve and extend to the effector tissue/organ at approx. that vertebral level
Describe the parasympathetic pathways.
-as parasympathetic neurons originate from the brainstem or the sacrum
1) preganglionic neurons leave the brain or spinal cord at the level of the sacrum
2) preganglionic neurons meet postganglionnic neurons in gangia close to viscera
3)postganglionic neurons travel to effector organs
