Chapter 9 Human Physiology

Autonomic Nervous System (ANS)

A part of the nervous system that regulates key autonomic functions of the body, including heart and blood vessel activity, smooth muscles, and endocrine glands.

Sympathetic Division

Division of the autonomic nervous system that responds to emergency stimuli, often associated with 'fight or flight' responses.

Parasympathetic Division

Division of the autonomic nervous system that returns the body to baseline conditions, often referred to as 'rest and digest'.

Central Nervous System (CNS)

Comprises the brain and spinal cord.

Peripheral Nervous System (PNS)

Consists of sensory input and motor output information going to muscles and glands.

Preganglionic Neuron

The first neuron in the autonomic pathway that has its cell body in the CNS.

Postganglionic Neuron

The second neuron in the autonomic pathway that innervates the effector organ.

Autonomic Ganglia

Collections of cell bodies outside the CNS involved in autonomic nerve pathways.

Collateral Ganglia

Ganglia of the sympathetic division of the ANS, including the celiac, superior mesenteric, and inferior mesenteric ganglia.

Acetylcholine (ACh)

The neurotransmitter for all preganglionic axons and most parasympathetic postganglionic axons.

Norepinephrine (NE)

A neurotransmitter released by sympathetic postganglionic axons that increases heart rate and contraction strength.

Dual Innervation

The phenomenon where most visceral organs receive nerve fibers from both the sympathetic and parasympathetic divisions.

Nicotinic Receptors

Ligand-gated receptors that are always depolarizing and activated by acetylcholine.

Muscarinic Receptors

G-protein-coupled receptors that can either hyperpolarize or depolarize the target cell.

Cardiac Muscle Pacemaker Cells

Specialized cells in the sinoatrial node of the heart that regulate heart rate in response to autonomic signaling.

G-Protein Coupled Receptor Activation

Process initiated when norepinephrine binds to its receptor, causing a series of intracellular signaling events.

Rest and Digest

Term used to describe the primary action of the parasympathetic division.

Fight or Flight

Term used to describe the primary action of the sympathetic division.

Sympathetic Chain Ganglia

A chain of sympathetic ganglia located parallel to the vertebral column.

Vasodilation

The widening of blood vessels, primarily influenced by the parasympathetic division.