function of ans

Fight or Flight: General Functions of the Autonomic Nervous System

ANS regulates organs/processes not under conscious control including:

circulation

digestion

respiration

temperature

sweating

metabolism

some endocrine gland secretions

Sympathetic system is most active when the body needs to react to changes in the internal or external environment: The requirement for sympathetic activity is most critical for:

temperature regulation

regulation of glucose levels

rapid vascular response to hemorrhage

reacting to oxygen deficiency

During rage or fright the sympathetic system can discharge as a unit--affecting multiorgan systems.

Sympathetic fibers show greater ramification.

Sympathetic preganglionic fibers may traverse through many ganglia before terminiating at its post-ganglionic cell. Synaptic terminal arborization results in a single preganglionic fiber terminating on many post-ganglionic cells.

This anatomical characteristic is the basis for the diffuse nature of sympathic response in the human and other species.

Sympathetic Responses

heart rate increases

blood pressure increases

blood is shunted to skeletal muscles

blood glucose increase

bronchioles dilate

pupils dilate

Parasympathetic responses

slows heart rate

protects retina from excessive light

lowers blood pressure

empties the bowel and bladder

increases gastrointestinal motility

promotes absorption of nutrients