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
- control center & communication system
- maintain homeostasis
- 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)