the nervous system12

8/8/2019 The Nervous System12

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THE NERVOUS SYSTEM



The Nervous System



P eripheral Nervous System

How to remember: Fingers and toes lie in theoutermost areas of the body from the center,

or the periphery of the bodyC onnects the rest of the body to the C entralNervous System.Broken down into two components:

Somatic Nervous SystemAutonomic Nervous System



Somatic Nervous System

E nables voluntary control of our skeletalsystem

How to remember: Volunteer work is done bychoice, so the body s (or soma s) voluntaryactions are controlled by this nervous system.



Autonomic Nervous System

T he part of the nervous system that controls theglands and the muscles of your internal organs.Broken up into the Sympathetic and

Parasympathetic Nervous systemsHow to remember: Aut onom ic sounds like the worda ut oma t ic, and the body s automatic actions(breathing, heartbeat) are controlled by thisnervous system.Is a key player for emotions, stress and healthT he fight or flight response is governed by theAutonomic Nervous system.

Plays a role in how we respond to stress or theenvironment.



Sympathetic Nervous System

Arouses and expendsenergyIf something alarms you,this allows your body toreact.

Increase heartbeat, raiseblood pressure

T hink about what thesympathetic nervoussystem does when wefeel sympathy

We try to help actively bycomforting and consolingothers.We have to act to consoleothers, so thesympathetic system willkick in, giving us theenergy to accomplish ourgoals



P arasympathetic Nervous System

C alms the body,conserves energyReduces heart rate,lowers blood pressureSympathetic andParasympathetic

systems together makean opponent processT hey work inopposition to eachother, with onesystem performingone role and theother systemperforming theexact opposite roleSympatheticParasympathetic

Opposition =h omeostasis (balance)



Central Nervous System

T he brain and spinal cordHow to remember: T he brain and spinal cord

are located in the cen t er of the body

Stephen C olbert: How does the brain work?

Five words or less.Steven Pinker: Brain cells fire in patterns.



Neural Networks

A grain-of-sand-speck of your brain contains 100,000 neurons and one billion

talking synapses.Neurons network (link) together in order to have short, fast communication.Learning occurs as feedback strengthens these connectionsT he dendrites of a neuron contribute significantly to the complexity of theneural network

T he more dendrites a neuron has, the greater number of connections that one neuroncan make with other neurons, increasing the likelihood that its message will get passedalong the chain.



Spinal Cord

T he information highway that connects theperipheral nervous system to the brain.

Ascending neural fibers (sensory neurons) send

sensory infoC onnect to the spinal cord dorsally (in the back)D escending fibers (motor neurons) send back motor-control info.

C onnect in the anterior of the spinal cord or in the front.

T hese neural pathways govern our reflexesAutomatic response to stimuliSimple pathway= Single sensory neuron and a singlemotor neuron, often communicating through aninterneuron.



T hese neural pathways governour reflexesAutomatic response to stimuliSimple pathway= Single sensoryneuron and a single motor neuron,often communicating through aninterneuron.

R eflexes and P ain

Interneurons make reflexes happenT hese cells in the spinal cord process

motor responses quickly to protect thebody from harm.Without interneurons, you wouldexperience severe burns if you left yourhand on the hot surface long enough to

process both the heat and the painbefore jerking away.



Reflex Arc

Sensory

informationenters the bodythrough

receptor cells

T he brainprocesses thesensory infoand decideswhat to do

Motor nervesreceive

commandsfrom the brain

and react.

the nervous system12

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