Nervous system intro

Introduction to the Introduction to the Nervous SystemNervous System

Chapter 9: Nervous SystemChapter 9: Nervous System

Unit 3: Integration and Unit 3: Integration and CoordinationCoordination

Nervous System Nervous System FunctionFunction The nervous system performs three The nervous system performs three

primary functions in the human bodyprimary functions in the human body– 1. The most obvious is that it 1. The most obvious is that it

coordinates our movements using coordinates our movements using electrochemical signals to control electrochemical signals to control muscle contraction.muscle contraction.

– 2. Also used to 2. Also used to sensesense the the internalinternal & & externalexternal environment environment

– 3. Finally, it 3. Finally, it integratesintegrates senses to form senses to form emotions and sensationsemotions and sensations

Nervous System Nervous System FunctionFunction Overall the Nervous system is one of Overall the Nervous system is one of

two systems that helps to maintain two systems that helps to maintain that all important that all important homeostasishomeostasis– Uses sensors and effectors to maintain Uses sensors and effectors to maintain

important physiological set points.important physiological set points.– *the other system that helps maintain *the other system that helps maintain

homeostasis would be the homeostasis would be the endocrine endocrine systemsystem

Nervous System Nervous System AnatomyAnatomy The structural basis of the nervous The structural basis of the nervous

system is a special cell called the system is a special cell called the neuronneuron

There are additional cells in the There are additional cells in the nervous system called nervous system called neuroglial neuroglial cellscells– Perform support roles such as Perform support roles such as

absorbing nutrients and phagocitizing absorbing nutrients and phagocitizing pathogens in the nervous systempathogens in the nervous system

Nervous System Nervous System AnatomyAnatomy Neurons are specialized cells that Neurons are specialized cells that

are capable of carrying are capable of carrying electrochemical signals long electrochemical signals long distancesdistances– Specialized ion channelsSpecialized ion channels– Specialized ion pumpsSpecialized ion pumps– Lots of ATPaseLots of ATPase

Nervous System Nervous System AnatomyAnatomy


Neurons have Neurons have three distinct three distinct partsparts– Cell bodyCell body– Dendrites (many)Dendrites (many)– Axon (single)Axon (single)


Nervous system Nervous system uses nerves to uses nerves to communicate communicate between body partsbetween body parts

Nerves are bundles Nerves are bundles of axons from of axons from multiple neuronsmultiple neurons

Act like telephone Act like telephone wires in the bodywires in the body

Divisions of the NSDivisions of the NS

The nervous system and its organs The nervous system and its organs can be divided into two major can be divided into two major groups:groups:

– Central Nervous System (Central Nervous System (CNSCNS)) Includes the brain & spinal cordIncludes the brain & spinal cord

– Peripheral Nervous System (Peripheral Nervous System (PNSPNS)) Includes the nerves and ganglia that Includes the nerves and ganglia that

connect the CNS to the rest of the bodyconnect the CNS to the rest of the body


CNSCNS– Responsible for integration of sensesResponsible for integration of senses– Development of emotionsDevelopment of emotions– Coordinates movementsCoordinates movements


PNSPNS– Responsible for Responsible for sensory functionssensory functions

The five sensesThe five senses Can use free nerve ends such as those Can use free nerve ends such as those

used to sense heat/cold OR…used to sense heat/cold OR… Be connected to specialized sense Be connected to specialized sense

organs such as the cones/rods of the organs such as the cones/rods of the retina (eye), the taste buds, or the retina (eye), the taste buds, or the special organs that sense touch and special organs that sense touch and pressure in the skinpressure in the skin


PNSPNS– Also responsible for Also responsible for motor motor

functionsfunctions Telling muscles when to contractTelling muscles when to contract Controlling heart rateControlling heart rate Controlling blood pressure by making Controlling blood pressure by making

vessels constrict/dilate (also controls vessels constrict/dilate (also controls temperature homeostasis)temperature homeostasis)

Controlling breathingControlling breathing


The The motor partmotor part of the peripheral of the peripheral nervous system can be further nervous system can be further divided into two categories based divided into two categories based on responsiveness:on responsiveness:

– The The Autonomic Nervous SystemAutonomic Nervous System

– The The Somatic Nervous SystemSomatic Nervous System


Autonomic Nervous SystemAutonomic Nervous System– Controls and coordinates parts of Controls and coordinates parts of

the body that are not under the body that are not under voluntary controlvoluntary control

– Called Called involuntary actionsinvoluntary actions Heart rateHeart rate Blood PressureBlood Pressure DigestionDigestion


Somatic Nervous SystemSomatic Nervous System– Responsible for all actions that are Responsible for all actions that are

preformed preformed voluntarilyvoluntarily– Skeletal muscle contractionsSkeletal muscle contractions


The Autonomic Nervous System The Autonomic Nervous System can be divided still farther into can be divided still farther into two groups that affect the human two groups that affect the human body in opposite waysbody in opposite ways

– Sympathetic Nervous SystemSympathetic Nervous System

– Parasympathetic Nervous Parasympathetic Nervous SystemSystem


The The Sympathetic Nervous SystemSympathetic Nervous System– Part of the autonomic nervous systemPart of the autonomic nervous system– Responds Responds involuntarilyinvoluntarily to danger/stress to danger/stress– Results in the Results in the fight or flightfight or flight response response

Heart rate???Heart rate??? Blood pressure???Blood pressure??? Pupils???Pupils??? Digestion???Digestion???


The The Parasympathetic Nervous Parasympathetic Nervous SystemSystem– Responds Responds involuntarilyinvoluntarily – Results in a soothing/calming Results in a soothing/calming

responseresponse– Usually responds once a Usually responds once a

stressful/fearful stimulus is removedstressful/fearful stimulus is removed

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Nervous system intro