Session 15 - Autonomic Nervous System Flashcards
What are the 2 functional subdivisions of the ANS?
- Sympathetic
- Parasympathetic
On which vertebral level is the sympathetic nervous system located?
T1-L2
On which part of the spinal column does the sympathetic nervous system synapse?
The lateral horn
Define autonomic nervous system
Those neurons, located within both the central and peripheral nervous systems, that are concerned with the innervations and control of visceral organs, smooth muscle and secretory glands
What is the general function of the sympathetic nervous system?
It prepares the body for stressful or emergency situations (fight or flight). It can do so. By increasing heart rate and the force of heart contractions and dilating the airways to make breathing easier,
What is the general function of the parasympathetic nervous system?
It conserves and restores body processes. It stimulates the digestive tract to process food and eliminates wastes.
Which part of the brain is responsible for the integration of the autonomic nervous system?
Hypothalamus
What is the function of the autonomic nervous system in the heart?
It is responsible for regulating heart rate, the force of each contraction and cardiac output.
Describe the parasympathetic innervation of the heart.
The preganglionic fibres emerge with the 10th cranial nerve, the Vagus nerve, from the brainstem and synapse with the postganglionic neuron in a ganglion in the wall of the heart.
The post-ganglionic fibres supply the SA node.
Describe the sympathetic innervation of the heart.
Pre-ganglionic neurons originate in the lateral grey matter column of the spinal cord and emerge with the ventral roots of spinal nerves T1-T4. The neurons pass to the sympathetic chain.
The post-ganglionic neurons synapse with the cell body of pre-ganglionic neurons in the ganglia of the sympathetic chain.
The post-ganglionic neurons, sympathetic cardiac nerves, supply the SA node and the cardiac muscle.
Describe the parasympathetic innervation of the digestive system.
The pre-ganglionic neurons emerge with the 10th cranial nerve, the Vagus nerve, from the brainstem or emerge from the ventral roots of the sacral spinal nerves from S2-S4.
The parasympathetic neurons of the Vagus nerve supply the proximal part of the gastro-intestinal tract up to the left colic flexure.
The parasympathetic neurons from the sacral part supply the distal part of the gastro-intestinal tract not supplied by the Vagus nerve.
Parasympathetic inputs enhance secretory activity and motility
Describe the sympathetic innervation of the digestive system.
Pre-ganglionic neurons originate from the lateral grey matter column of the spinal cord and emerge with the ventral roots of the thoracic and upper 2 lumber spinal nerves (T1-L2). They are called splanchnic nerves and pass through the sympathetic chain without making a synapse. They synapse in ganglia located around the large branches of the abdominal aorta.
