12 - Autonomic Nervous System – Vocabulary Flashcards (Video Notes)

Vocabulary flashcards covering key autonomic nervous system concepts from the video notes.

Autonomic sensory components

Receptors that monitor visceral states; information is usually not consciously perceived.

Autonomic motor components

Innervate involuntary effectors (glands, smooth muscle, cardiac muscle); differ from somatic in the number of neurons and neurotransmission.

Efferent (motor) neurones

Neurons that carry impulses from the CNS to effector cells.

CNS

Central Nervous System: the brain and spinal cord.

Somatic neurotransmission

Discrete, targeted release of neurotransmitter at a neuromuscular junction.

Autonomic neurotransmission

Diffuse release of neurotransmitters affecting multiple cells/organs.

Sympathetic nervous system

Branch of the autonomic system involved in stress responses (fight-or-flight).

Parasympathetic nervous system

Branch of the autonomic system promoting rest-and-digest activities.

Adrenal medulla

Modified sympathetic ganglion; receives preganglionic input and releases adrenaline (epinephrine) into blood.

Adrenaline (epinephrine)

Hormone released by the adrenal medulla; acts on distant receptors to produce widespread effects.

Dual innervation

Most organs receive input from both SNS and PNS, often with opposing (antagonistic) actions.

Antagonistic

Opposing actions of SNS and PNS on the same organ.

Pupil dilation (mydriasis)

Sympathetic stimulation causing pupil enlargement.

Pupil constriction (miosis)

Parasympathetic stimulation causing pupil narrowing.

Heart – sympathetic effect

Increases heart rate and force of contraction.

Heart – parasympathetic effect

Decreases heart rate.

GIT – sympathetic effect

Decreases motility and secretions; constricts sphincters.

GIT – parasympathetic effect

Increases motility and secretions; relaxes sphincters.

Vasomotor tone

Baseline vascular tone maintained by sympathetic activity, determining vessel diameter.

Alpha-1 adrenergic receptor (α1)

Mediator of vasoconstriction in many vessels when stimulated by norepinephrine.

Beta-2 adrenergic receptor (β2)

Mediator of vasodilation in skeletal muscle and some vessels via epinephrine.

Norepinephrine (NA)

Primary sympathetic postganglionic neurotransmitter; acts on α and β receptors.

Sweat glands

Primarily innervated by sympathetic nerves; sweating is regulated by sympathetic activity.

Vasodilation in skeletal muscle under SNS

SNS activation can cause vasodilation in skeletal muscle via β2 receptors and circulating epinephrine.

Vasoconstriction via SNS

SNS activation causing constriction in many vessels via α1 receptors.

Blood vessels in head/reproductive organs

Innervation patterns vary; regions may have dual innervation or region-specific control.

Blood vessels in skeletal muscle and heart (SNS effects)

SNS can promote vasodilation in these beds (via β2 and epinephrine) or vasoconstriction in others (via α1) depending on receptors and context.

Interaction of autonomic and somatic systems

Coordinated control of functions, e.g., eye focusing (parasympathetic + somatic) and cold response (autonomic + somatic).

Eye focusing on a near object

Parasympathetic-driven lens accommodation coordinated with somatic eye movements.

Response to cold

Autonomic vasoconstriction to conserve heat, often accompanied by somatic shivering.