Answers, BIO 2320, Autonomic Nervous System




1. It is part of the peripheral nervous system, generally involving a preganglionic neuron & a postganglionic neuron. The preganglionic for SNS exits the spinal cord in the T1-L2 region. The preganglionic for the PNS exits the spinal cord in the S2-S4 region plus the brain stem along with cranial nerves III, VII, IX and X. They postganglionic neurons innervate visceral structures such as smooth muscle, cardiac muscle and glands.

2. Parasympathetic (PNS, rest & relaxation) and Sympathetic (SNS, fight or flight)

3. Neurotransmitters are chemicals that carry impulses across synapses. Acetylcholine is the neurotransmitter released from the preganglionic neurons in both PNS and SNS AND for the postganglionic neuron in PNS. Norepinephrine is the neurotransmitter released by the postganglionic neuron in SNS.

4. Covered in #1

5. Hypothalamus is the control center for Autonomic Nervous System.

6. Heart: PNS decreases rate & strength of contraction, SNS is opposite

Lungs: PNS decreases size of airways & SNS is opposite

Digestion: PNS increases movement & secretions in all of digestion & SNS is opposite

Pupil: PNS constricts pupil, SNS dilates pupil.

Sweat glands: Only innervated by SNS and it causes you to sweat

Adrenal medulla: Only innervated by preganglionic neurons in SNS and it causes the adrenal medulla to release epinephrine & norepinephrine to exaggerate the fight or flight response.

Cutaneous & abdominal blood vessels: Only innervated by SNS and it causes them to constrict to decrease blood flow.

Skeletal muscle blood vessels: Only innervated by SNS and it causes them to dilate to increase blood flow.