Nervous System and Ventral Cavity

Somatic and Autonomic

What are the divisions of the peripheral nervous system (PNS)?

Skeletal muscle

The somatic nervous system innervates

Smooth muscle, Cardiac muscle, and Glands

The autonomic nervous system innervates

SNS- one neuron system

ANS- two neuron system (preganglionic neuron and postganglionic neuron)

How many neurons do the somatic and autonomic nervous systems use?

Acetylcholine (ACh), always excitatory

Somatic NS releases what neurotransmitter?

Acetylcholine (ACh)

Autonomic NS Preganglionic fibers all release what neurotransmitter?

Norepinephrine(most); exictatory

ANS Postganglionic sympathetic fibers release what neurotransmitter?

Ach; inhibitory

ANS Postganglionic parasympathetic fibers release what neurotransmitter?

Craniosacral, brain stem CN 3, 7, 9, 10 and S2-S4

Parasympathetic origin

Thoracolumbar, T1-L2

Sympathetic origin

Parasympathetic: Long pre, short post

Sympathetic: Short pre, long post

Relative lengths of fibers

Parasympathetic, in/near visceral effector organs (intramural)

Sympathetic, paravertebral (chain) and prevertebral (splachnic on branches of the aorta)

Location of ganglia

CN III, Oculomotor

Innervates smooth muscles in eye

CN VII, Facial

Innervates nasal, lacrimal, submandibular, and sublingual glands

CN IX, Glossopharyngeal

Innervates parotid gland

CN X, Vagus

Innervates heart, lungs, liver, gallbladder, stomach, small intestines, pancreas, and proximal 1/2 of large intestines

Pelvic Splanchnic nerves (S2-S4) Lateral gray matter of spinal cord

Sacral parasympathetics

Innervates distal 1/2 of large intestines, urinary bladder, ureters, and reproductive organs

Leave the spinal cord through the ventral root, pass into spinal nerve, travel through white rami communicans into paravertebral ganglion on the sympathetic chain then can

1) Synapse with postganglionic neuron that exits the chain through the gray ramus communicans and enters either the ventral or dorsal ramus of the adjoing spinal nerve

2) Ascend or descend in the sympathetic chain and synapse with postganglionic neuron in a different paravertebral ganglion, fiber exits the sympathetic chain through the gray ramus communicans and enters either the ventral or dorsal ramus of the adjoining spinal nerve

3) Leaves the sympathetic chain without synapsing and forms a splanchnic nerve, goes to visceral organs

3 pathways of sympathetics

White ramus communicans

Myelinated

Preganglionic

Only found at T1-L2

Gray ramus commincans

Unmyelinated Postganglionic

Found all along spinal cord

Visceral organs

What typically receives dual innervation (sympathetic and parasympathetic)?

Cardiac muscle of the heart and smooth muscle of the digestive and urinary tract organs

What typically receives dominate innervation from the parasympathetic, but can be overridden by sympathetic during stress?

Blood vessels (mediates body temperature)

Adrenal medulla, sweat glands of skin, arrector pili muscles of skin, and kidneys

What typically receives only sympathetic innervation?

Thoracic (Right and left Pleural cavity and Mediastinum which holds the pericardial cavity)

Abdominopelvic (Abdominal and Pelvic cavities)

Cavities of the Ventral body cavity

Parietal layer

lines the walls of the cavity

Visceral layer

adheres to the surface of the organ

Serous fluid

A thin layer of fluid located between the parietal and visceral layers

Reduces friction when the viscera move

Parietal/ visceral pleura

Found around the lungs

Parietal/ visceral pericardium

Found around the heart

Parietal/ visceral peritoneum

Found in the abdominopelvic cavity