Afferent Neurons

Sensory neurons take input toward CNS. Attach to sensory receptors.

Efferent Neurons

Motor neurons take output away from CNS. Attach to effectors (muscles and glands)

Central Nervous System

Composed of mostly cell bodies of neurons.

Brain (gray matter =cell bodies; white matter =axons

Spinal Cord

Peripheral Nervous System (PNS)

Nervous system through out body except brain & spinal cord.
Contains
-Afferent (from Somatic, Special & Visceral Senses)
-Efferent (to Somatic & Autonomic Effectors which also split into sympathetic and parasympathetic divisions)

Nerve

Bundle of axons (nerve fibers) in PNS.

*Tract/Pathway = bundle of axons in CNS

Ganglia

Cluster of cell bodies in PNS

Nervous System Functions

1. control center & communication system
2. maintain homeostasis
3. Sensation →Integration (Processing) →Response

Divisions of the Efferent Nervous System

Somatic →Skeletal Muscle *usually voluntary from cerebral cortex
Autonomic →Sympathetic (fight/flight)
→Parasympathetic (rest/digest)
Symp & Para both go to Cardiac muscle / Smooth Muscle / Glands

Somatic Nervous System (SNS) of Efferent Nervous System

Part of Efferent Peripheral Nervous System
Usually voluntary
No Ganglia
Control Skeletal Muscle (effectors)
One Synapse →ALWAYS ACh "cholinergic" and ALWAYS excitatory (open Na+ & cause depolarization for muscle contraction)

Autonomic Nervous System (ANS)

Part of Efferent Peripheral Nervous System
Involuntary (controlled by Pons / Medulla Oblongata / Hypothal)
Controls Cardiac Muscle, Smooth Muscle, Glands (effectors)
Including: Cardiovascular, respiratory, digestive urinary, reproductive functions
Splits into 2 divisions:
Sympathetic (fight/flight) & Parasympathetic (rest/digest)

Sympathetic Nervous System

Fight or Flight Response
Part of Autonomic Nervous System
Dual innervation (with Parasympathetic) to Cardiac muscle, smooth muscle and glands.

Parasympathetic Nervous System

Rest & Digest or Feed & Breed
Part of Autonomic Nervous System
Dual innervation (with Sympathetic) to cardiac muscle, smooth muscle, glands

ANS anatomical route from CNS to Effector

Preganglionic Neuron→Synapse (ACh & Excitatory "Cholinergic")→Postganglionic Neuron→
*Sympathetic Div= release Norepinephrine "Adrenergic" →Effector
*Parasympathetic = release ACh "Cholinergic"→Effector
Postganglionic NE can be excitatory or inhibitory

Norepinephrine

Usually released as Neurotransmitter
Released from Adrenal Medulla releases diretly into blood vessels
Prolongs sympathetic response (fight/flight)