Chapter 14: The Autonomic Nervous System and Homeostasis

A complete set of vocabulary flashcards covering the anatomical divisions, receptors, and physiological effects of the Autonomic Nervous System as presented in the Chapter 14 lecture.

Autonomic Nervous System (ANS)

The division of the peripheral nervous system that regulates involuntary physiological processes like heart rate and digestion through visceral reflex arcs.

Visceral Reflex Arcs

A pathway involving afferent sensory neurons and efferent motor neurons that integrate internal stimuli to trigger involuntary responses in target organs.

Preganglionic Neuron

The first motor neuron in an autonomic pathway, which has its cell body in the CNS and synapses with a secondary neuron.

Postganglionic Neuron

The second motor neuron in the autonomic pathway, with its cell body in a PNS ganglion and its axon terminating at the target cell.

Sympathetic Nervous System

Also known as the 'fight or flight' division, this system prepares the body for physical activity, emergencies, and emotional stress.

Thoracolumbar Division

A descriptive name for the sympathetic nervous system, reflecting that its preganglionic neurons originate in the thoracic and upper lumbar regions of the spinal cord.

Parasympathetic Nervous System

The 'rest and digest' division of the ANS, primarily responsible for body maintenance functions such as digestion and urine formation.

Craniosacral Division

A descriptive name for the parasympathetic nervous system, indicating that its preganglionic neurons originate in the brainstem and the sacral region of the spinal cord.

White Rami Communicantes

Small, myelinated nerves that carry preganglionic sympathetic axons from spinal nerves to the sympathetic chain ganglia.

Gray Rami Communicantes

Unmyelinated nerves that allow postganglionic sympathetic axons to exit ganglia and rejoin spinal nerves to reach their targets.

Sympathetic Chain Ganglia

A series of ganglia located along the vertebral column containing the cell bodies of most postganglionic sympathetic neurons.

Collateral Ganglia

Sympathetic ganglia located near the target organs, separate from the chain ganglia, often situated near the aorta.

Splanchnic Nerves

Preganglionic sympathetic axons that bypass the chain ganglia to synapse in collateral ganglia within the abdominopelvic cavity.

Adrenergic Receptors

Receptors that bind norepinephrine or epinephrine, categorized into alpha and beta subtypes.

Alpha-1 Receptors

Adrenergic receptors located on the membranes of smooth muscle cells in blood vessels and the gastrointestinal system that typically cause contraction.

Alpha-2 Receptors

Receptors often found on preganglionic sympathetic neurons that hyperpolarize the cell to inhibit or dampen the sympathetic response.

Beta-1 Receptors

Adrenergic receptors primarily found in the membranes of cardiac muscle cells and certain kidney cells.

Beta-2 Receptors

Adrenergic receptors on the smooth muscle of the bronchioles and urinary bladder that facilitate relaxation and dilation.

Beta-3 Receptors

Receptors located in adipose tissue and the digestive tract that influence lipid breakdown and muscle relaxation.

Cholinergic Receptors

Receptors that bind to the neurotransmitter acetylcholine, classified as either muscarinic or nicotinic.

Muscarinic Receptors

Cholinergic receptors found on sweat glands and all parasympathetic target cells.

Nicotinic Receptors

Cholinergic receptors located on the membranes of all postganglionic neurons and the cells of the adrenal medulla.

Adrenal Medulla

A modified sympathetic ganglion that releases approximately $80\%$ epinephrine and $20\%$ norepinephrine into the bloodstream as hormones.

Terminal Ganglia

Parasympathetic ganglia located near or within the walls of the target organs.

Pelvic Splanchnic Nerves

Nervous branches originating from the sacral spinal cord segments $S2-S4$ that provide parasympathetic innervation to pelvic organs.

Autonomic Tone

The constant background level of activity from both the sympathetic and parasympathetic systems that maintains homeostasis.

Dual Innervation

The physiological arrangement where an organ receives instructions from both the sympathetic and parasympathetic divisions to balance its function.

Postural Orthostatic Tachycardia Syndrome (POTS)

A condition characterized by an abnormal increase in heart rate and drop in blood pressure when moving from a sitting to a standing position.

Autonomic Centers

Areas within the brainstem reticular formation that receive input from the hypothalamus to control autonomic preganglionic neurons.