The Nervous SystemThe Nervous System

Functions of the Nervous SystemFunctions of the Nervous System

1.1. Control center for all body activitiesControl center for all body activities2.2. Responds and adapts to changes that Responds and adapts to changes that

occur both inside and outside the bodyoccur both inside and outside the body (Ex: pain, temperature, pregnancy)(Ex: pain, temperature, pregnancy)

Central Nervous SystemCentral Nervous System

NeuronsNeurons : microscopic : microscopic nerve cells that make nerve cells that make up the brain, spinal up the brain, spinal cord, and nervescord, and nerves

- 30,000 neurons can fit - 30,000 neurons can fit on a pinheadon a pinhead

Anatomy of a NeuronAnatomy of a Neuron

Each neuron contains:Each neuron contains: - - Cell bodyCell body with with

nucleusnucleus - - DendritesDendrites : fibers that : fibers that

receive messages from receive messages from other neuronsother neurons

- - AxonsAxons : fibers that : fibers that send messages to other send messages to other neuronsneurons

• Neurons do NOT touch; Neurons do NOT touch; there is a gap between there is a gap between them called a them called a synapsesynapse

• Messages are sent Messages are sent across the synapses by across the synapses by special chemicals called special chemicals called neurotransmittersneurotransmitters

Communication Between Communication Between NeuronsNeurons

- The use of The use of neurotransmitters neurotransmitters causes an electrical causes an electrical currentcurrent

There is enough There is enough electrical current in electrical current in the brain to power a the brain to power a flashlightflashlight

Two Major Divisions Two Major Divisions of the Nervous of the Nervous

SystemSystem

Central Nervous SystemCentral Nervous SystemBrainBrain : a mass of 100 : a mass of 100

billion neurons located billion neurons located inside the skullinside the skull

-Learning occurs as more -Learning occurs as more and stronger and stronger connections are made connections are made between neuronsbetween neurons

Anatomy of the BrainAnatomy of the Brain

CerebrumCerebrum : largest part of : largest part of human brainhuman brain

- Responsible for:- Responsible for: - Thought- Thought - Language- Language - Senses- Senses - Memory- Memory - Voluntary movement- Voluntary movement

Retrieval of a MemoryRetrieval of a Memory

A memory is not a A memory is not a snapshot stored in the snapshot stored in the brain – it must be put brain – it must be put together from together from information stored in information stored in various parts of the various parts of the brainbrain

Anatomy of the BrainAnatomy of the BrainCerebellum : at base of

brain-Responsible for: - Muscle coordination - Balance - Posture

Anatomy of the BrainAnatomy of the BrainBrain StemBrain Stem : connects : connects

brain to spinal cordbrain to spinal cord-Responsible for:-Responsible for: - Breathing- Breathing - Swallowing- Swallowing - Heartbeat- Heartbeat - Blood pressure- Blood pressure

Central Nervous SystemCentral Nervous SystemSpinal CordSpinal Cord : Column of : Column of

nerves from brain to nerves from brain to tailbone – protected by tailbone – protected by vertebrae of spinevertebrae of spine

- Responsible for:Responsible for: - Conducting - Conducting

impulses between the impulses between the brain and the rest of brain and the rest of the bodythe body

*Impulses may travel as *Impulses may travel as

fast at 268 miles/hrfast at 268 miles/hr

Peripheral Nervous SystemPeripheral Nervous System

NervesNerves : visible bundles : visible bundles of axons and dendrites of axons and dendrites that entend from the that entend from the brain and spinal cord to brain and spinal cord to all other parts of the all other parts of the body body

-Responsibilities:-Responsibilities: - - Sensory nervesSensory nerves - -

carry messages from carry messages from body to brain (pain, body to brain (pain, pressure, temperature)pressure, temperature)

- - Motor nervesMotor nerves – carry – carry messages from brain messages from brain to body to respond to body to respond

Problems of the Nervous SystemProblems of the Nervous System

ConcussionConcussionA temporary disturbance A temporary disturbance

of the brain’s ability to of the brain’s ability to function due to a hard function due to a hard blow to the headblow to the head

ParalysisParalysisA loss of sensation and A loss of sensation and

movement of part of movement of part of the body due to an the body due to an injury of the spinal injury of the spinal cord or braincord or brain

EpilepsyEpilepsyAbnormal transmission of messages between the Abnormal transmission of messages between the

neurons in the brain neurons in the brain Symptoms: seizuresSymptoms: seizures