t4: PNS

Function of the Somatic Nervous System?

connects the external environment with the central nervous system (CNS), by bringing sensory information to the CNS and sending its motor commands from the CNS to skeletal muscles for voluntary movement.

What nerves make up the Somatic Nervous System?

made up of 12 pairs of cranial nerves (originating from the brain) and 31 pairs of spinal nerves.

• Cranial nerves control functions like vision, hearing, taste, smell, and facial movement.

• Spinal nerves control skeletal muscles throughout the rest of the body.

Function of the Autonomic Nervous System (ANS)?

controls the body’s internal environment.
It sends signals between the CNS and internal effectors like smooth muscle, cardiac muscle, organs, and glands. 

its control is involuntary

Two divisions of the autonomic nervous system?

• Sympathetic Nervous System – prepares the body for stress or emergencies (“fight or flight”).

• Parasympathetic Nervous System – restores and maintains normal body functions (“rest and digest”).

What are the main effects of the sympathetic and parasympathetic systems, on the following organs?:

Organ
Heart
Digestive tract
Liver
Eyes
Bladder
Skin
Adrenal gland

Organ	Sympathetic	Parasympathetic
Heart	Increases heart rate	Decreases heart rate
Digestive tract	Decreases peristalsis	Increases peristalsis
Liver	Releases glucose	Stores glucose
Eyes	Dilates pupils	Constricts pupils
Bladder	Relaxes sphincter	Contracts sphincter
Skin	Increases blood flow	Decreases blood flow
Adrenal gland	Releases epinephrine	No effect

Vagus Nerve

Connects parasympathetic nervous system to the brain