Chapter 9 Notes from Knowt

Autonomic Nervous System (ANS)

Regulates involuntary bodily functions such as heart rate, blood circulation, smooth muscle activity, and endocrine gland responses.

Sympathetic Division

Triggers fight-or-flight responses, resulting in increased heart rate, narrowing of blood vessels, and decreased digestive activity.

Parasympathetic Division

Promotes rest-and-digest functions characterized by decreased heart rate, widening of blood vessels, and enhanced digestive processes.

Central Nervous System (CNS)

Comprises the brain and spinal cord.

Peripheral Nervous System (PNS)

Contains spinal and cranial nerves, relaying sensory information to the CNS and motor commands to muscles and glands.

Preganglionic Neuron

Cell body located in the CNS, synapses in an autonomic ganglion.

Postganglionic Neuron

Extends from the ganglion to the target organ (e.g., smooth muscle, cardiac muscle, glands).

Sympathetic Activation Effect

Norepinephrine release from postganglionic neurons leads to increased heart rate and enhanced energy mobilization in response to stress.

Parasympathetic Activation Effect

Acetylcholine from postganglionic fibers results in decreased heart rate and enhanced digestion by hyperpolarizing pacemaker cells.

Acetylcholine (ACh)

Primary neurotransmitter for all preganglionic fibers and most parasympathetic postganglionic fibers.

Norepinephrine (NE)

Released by sympathetic postganglionic fibers, impacting adrenergic receptors, especially in cardiac tissues.