INTRODUCTION TO VISCERAL ORGANS (L1)

What are the 2 divisions of the nervous system

What are the 2 divisions of the nervous system

• central nervous system

-peripheral nervous system

The central nervous system is composed of the

brain and the spinal cord

The peripheral nervous system divides into the

somatic and autonomic nervous system

The peripheral nervous system's nerves include

all the other nerves of the body

The autonomic nervous system is (involuntary/voluntary)

involuntary

the autonomic nervous system is the involuntary control of the

visceral organs

The autonomic nervous system splits into the

parasympathetic nervous system and sympathetic nervous system

State of parasympathetic nervous system

rest & digest e.g. decrease heart rate

State of sympathetic nervous system

fight & flight e.g. increase heart rate

Just like the somatic nervous system, the autonomic nervous system also has

visceral afferents and visceral efferents

Visceral afferents are

sensory inputs from organs e.g. pain

Visceral effents are

motor inputs to organs e.g. Peristalsis, dilation or constriction or blood vessels

Information in the sympathetic nervous system travels through a structure called the

sympathetic chain

A ganglia is a

concentration of cell bodies

The spinal cord: white matter is composed of

myelinated axons

The spinal cord: gray matter is composed of

cell bodies

The spinal cord: there is also a lateral horn

only present in the thoracic region associated with autonomic nervous system

The lateral horn is where

the information for the autonomic nervous system comes from the spinal cord

From the central nervous system to the target organ, there are 2

neuron chain responses

2 neuron chain responses of the sympathetic nervous system and parasympathetic nervous system

preganglionic neuron and postganglionic neuron

Characteristics of preganglionic neurons

myelinated and begin in the CNS

Characteristics of postganglionic neurons

Unmyelinated and synapse with neuron from CNS in the periphery

Preganglionic neuron of the sympathetic nervous system is

short

Preganglionic neuron of the parasympathetic nervous system is

long

postganglionic neuron of the sympathetic nervous system is

long

postganglionc neuron of the parasympathetic nervous system is

short

Synapses of the sympathetic nervous system

1. acetylcholine

2. norepinephrine`

Synapses of the parasympathetic nervous system

1. acetylcholine

2. acetylcholine

Origin of the sympathetic nervous system

T1-L2

T1-L2 are the branches to

a sympathetic chain/trunk that runs the whole length of the vertebral column but only attaches at these points

Origin of the parasympathetic nervous system

cranial and sacral nerves

Cranial nerves of the parasympathetic nervous system

CN III CN VII CN IX CN X - vagus nerve

Sacral nerve levels of the parasympathetic nervous system

S2-S4

The sympathetic chain/trunk

a chain of paravertebral ganglia which receives input from spinal cord levels T1-L2

The sympathetic trunk is connected to

the ventral ramus of our spinal nerves

There are white and grey communicans. This is how...

the info will leave/enter spinal cord/spinal nerve

4 sympathetic pathways

1. same level target organ

2. different level target organ

3. splanchnic nerve

4. direct synapse with preganglionic neuron

In all pathways

The preganglionic neuron will start in the lateral horn, leave the spinal cord through the ventral root, go through the spinal nerve and uses the white ramus communicans to come into the sympathetic chain

then...1-same pathway level

There, it will synapse in a ganglia at the same level and it will leave using the grey ramus communicans and exit at the same level through the ventral ramus to reach the target organ

2. different level target organ

The preganglionic neuron will then go up or down the sympathetic chain and synapse with the postganglionic neuron in a ganglia at a different spinal level and exit through the grey communicans and the ventral ramus

There are no lateral horns or white ramus communicans higher than ___ or lower than___

higher than T1 or lower than L2 b/c the preganglionic neuron cannot enter the chain outside these levels

3. splanchnic nerve

The preganglionic neuron will then leave the sympathetic chain through splanchnic nerves and synapse with a postganglionic neuron in a prevertebral ganglion to reach abdominal and pelvic organs

4.direct synapse with preganglionic neuron

The preganglionic neuron will then leave the sympathetic chain through splanchnic nerves and synapse directly with the target organ. There is no postganglionic neuron involved in this pathway

Review slide 1

Review slide 2

Sympathetic chain lab slide