ANS VS PNS Melanie Pacheco Signey MojicaKarina BenitezValeria Valdez

CENTRAL NERVOUS SYSTEM

• Organs divided into two major groups: Brain and Spinal Cord

• Responsible for sending and receiving information

PERIPHERAL NERVOUS SYSTEM

Includes:1) Cranial nerves that come from the Brain2)Spinal Nerves that come from the Spinal cord

Subdivided into:1)Somatic Nervous System 2) Autonomic Nervous System

SOMATIC NERVOUS SYSTEM

Voluntary Muscle Movements

Muscular movements and sensation

Contains two major types of Neurons:1) Sensory Neurons(Afferent)2) Motor Neurons(Efferent)

The neurons of SNS project from the CNS into the muscles and sensory organs. It is a direct path with synapses to connect nearby neurons.

AUTOMATIC NERVOUS SYSTEM

Controlled and part of PNS Involuntary Muscle Movements Regulates glands, cardiac, and smooth

muscle by returning them back to homeostasis; just like the reflex arc

Divided Into:1) Sympathetic Nervous System: “Fight or Flight”

2) Parasympathetic Nervous System: “Rest and Digest”

AUTONOMIC V.S SOMATIC

REFLEX ARC

Stimulus: a change in the environment

Response: react to the change in the environment

Receptors: cells specialized to react to a specific stimulus

CONT.

Reflexes Help Maintain Homeostasis By Controlling: Heart Rate Breathing Rate Blood Pressure Digestion

SYMPATHETIC DIVISIONS

o Location: thoratic and lumbar spinal cordo Helps the body when it is in need of energy,

under stress, and in emergency situationo Does this by:

o increases blood pressureo decrease digestiono Increase heart beat

o (fight or flight process)o Structure used:

o Adrenal glando Gray ramio Sympathetic trunkso Sympathetic chain ganglia

SYMPATHETIC GANGLIA CHAIN

Deliver information to the body Located in the spinalcord and extend from the upper neck down to the coccyx.

PREGANGLIONIC FIBERS

Nerve fibers that connect the central nervous system to ganglia

Sympathetic preganglionic fibers tend to be shorter than parasympathetic fibers and sympathetic fibers tend to form more synapses than parasympathetic fibers.

POSTGANGLIONIC FIBERS

In the autonomic nervous system, fibers from the ganglion to the effector organ are called postganglionic fibers.

Postganglionic fibers in the sympathetic division are adrenergic and use norepinephrine as a neurotransmitter.

Postganglionic fibers in the parasympathetic division are cholinergic and use acetylcholine as a neurotransmitter.

PARASYMPATHETIC DIVISION

Location: in sacral region of the spinal cord Allows the body to go back to the resting

state Counterbalances sympathetic division Returns to homeostasis

Structures used: Parathyroid gland Submandibular gland Sublingual gland

Neurotransmitters Receptors

REGULATION

Reflex centers receive sensory impulses from the viscera, and use autonomic nervous pathways to stimulate a motor response from the muscles or gland.

The hypothalamus helps regulate the body temperature, hunger, and electrolyte pathways.

The limbic system and cerebral cortex controls the autonomic nervous system during emotional stress.

TERMINATION

Acetyl Cholinesterase decomposes the acetylcholine and the acetylcholine affects the post synaptic membrane

Then norepinephrine is released from cholinergic fibers that go back to the presynaptic neurons.

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