Efferent Nervous System Review

These flashcards cover key concepts, definitions, and functions related to the Efferent Nervous System and its components.

Somatic Nervous System (SNS)

Controls skeletal muscle; voluntary movement.

Autonomic Nervous System (ANS)

Controls involuntary functions; targets smooth muscle, cardiac muscle, glands.

Sympathetic Nervous System

Part of the ANS; responsible for 'fight or flight' responses.

Parasympathetic Nervous System

Part of the ANS; responsible for 'rest and digest' functions.

Neurotransmitter: Acetylcholine (ACh)

Used in both preganglionic pathways of SNS and PNS.

Diverging neural pathways

Allows widespread activation of multiple organs by sympathetic nervous system.

Epinephrine (Epi)

Hormone released by adrenal medulla; enhances sympathetic responses.

Nicotinic receptors

Ionotropic receptors found in autonomic ganglia and skeletal muscle.

Muscarinic receptors

Metabotropic receptors found in parasympathetic target organs.

Metabotropic receptors

Receptors that use second messengers; slow and long-lasting effects.

Ionotropic receptors

Receptors that open ion channels directly; fast and short-lived effects.

Adrenergic receptors

G-protein-coupled receptors activated by norepinephrine; subtypes include α1, α2, β1, β2.

Preganglionic neurons

Neurons that originate in the CNS and release ACh.

Postganglionic neurons

Neurons that innervate target tissues; can release ACh or norepinephrine.

Cardiac Muscle

Involuntary muscle controlled by the autonomic nervous system.

Skeletal Muscle

Voluntary muscle controlled by the somatic nervous system.

Glands

Exocrine or endocrine structures affected by the autonomic nervous system.

Adipose Tissue

Fat tissue affected by the autonomic nervous system.

Mass Activation

The simultaneous activation of multiple organs during stress.

Vagus Nerve

Cranial Nerve X; innervates heart, lungs, digestive organs.

Tonic Control

Single system controls a function in a graded manner.

Antagonistic Control

Two systems work against each other to regulate a function.

Neuromuscular Junction (NMJ)

Synapse between a motor neuron and skeletal muscle.

Reflex control of ANS

Regulated by brainstem for functions like heart rate and breathing.

Hypothalamus

Master controller of the autonomic nervous system.

Adrenal Gland Medulla

Part of the sympathetic nervous system, releases epinephrine.

ACh Agonist effects on heart

Decreases heart rate.

NE Agonist effects on heart

Increases heart rate.

Bronchoconstriction

Narrowing of the air passages caused by ACh.

Bronchodilation

Widening of the air passages caused by norepinephrine.

Smooth Muscle

Involuntary muscle controlled by the autonomic nervous system.

Cardiovascular effects of ANS

Blood vessels are under tonic control by the sympathetic system.

Effects of ACh

Can be excitatory or inhibitory based on receptor type.

Release of NE

NE released via exocytosis; removal by reuptake and breakdown.

Varicosities

Enlargements along axons that release neurotransmitters over broad areas.

Ion channel opening process

Fast response mechanism of ionotropic receptors.

Signal transduction via G-proteins

Used by metabotropic receptors for longer-lasting effects.

Craniosacral origin

Origin of the parasympathetic nervous system.

Thoracolumbar origin

Origin of the sympathetic nervous system.

Reflexes

Automatic responses triggered by the brainstem control.

Skeletal muscle contraction mechanism

Depolarization at NMJ leads to muscle contraction.

P for Parasympathetic

Stands for peace and rest functions.

S for Sympathetic

Stands for stress and fight or flight functions.

Vagus nerve function

Involved in regulating heart, lungs, and digestive activities.

Nerve cell body location for Somatic neurons

Located in the ventral horn of the spinal cord.

Nerve cell body location for Autonomic neurons

Located in the lateral horn of the spinal cord.

Quick action of Nicotinic receptors

Ionotropic responses, providing fast effects.

Slow response of Muscarinic receptors

Metabotropic responses, providing slower effects.