Ppt chapter 19

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Introduction to Nerves and the Nervous System

Introduction to Nerves and the Nervous System

Chapter 19


Role of the Nervous SystemRole of the Nervous System

• Controlling the functions of the human body

• Analyzing incoming stimuli

• Integrating internal and external responses


Make Up of the Nervous SystemMake Up of the Nervous System

• Central Nervous System (CNS)

– Composed of the brain and spinal cord

• Peripheral Nervous System (PNS)

– Sensory receptors bring information into the CNS

– Motor nerves carry information away from the CNS

• Autonomic Nervous System (ANS)

– Uses components of the CNS and PNS to regulate automatic or unconscious responses to stimuli


Function of the Cells that Make Up the Nervous System

Function of the Cells that Make Up the Nervous System

• Allow movement

• Allow realization of various sensations

• Provide response to internal and external stimuli

• Stimulate learning, thinking, and emotions


NeuronNeuron


Types of Neuron AxonsTypes of Neuron Axons

• Afferent Fibers

– Nerve axons that run from peripheral receptors into the CNS

• Efferent Fibers

– Nerve axons that carry nerve impulses from the CNS to the periphery to stimulate muscles or glands


Action PotentialAction Potential


Electrolytes Involved in Nerve Cell ActionElectrolytes Involved in Nerve Cell Action

• Sodium

• Potassium

• Calcium


Movement of Electrolytes with ActionMovement of Electrolytes with Action

• Rest/Repolarization

– Membrane is impermeable to sodium

– Permeable to potassium

• Action/Depolarization

– Sodium goes into the cell

– Potassium leaves the cell


Formation of Myelin SheathFormation of Myelin Sheath


Nerve SynapseNerve Synapse

• Presynaptic Nerve

• Synaptic Cleft

• Postsynaptic Effector Cell


QuestionQuestion

What nerve axons carry nerve impulses from the central nervous system to the peripheral nervous system?

A. Somatic axons

B. Efferent fibers

C. Afferent fibers

D. Sensory axons


AnswerAnswer

B. Efferent fibers

Rationale: Efferent fibers–Nerve axons that carry nerve impulses from the CNS to the periphery to stimulate muscles or glands


NeurotransmittersNeurotransmitters

• Acetylcholine

– Communicates between nerves and muscles

• Norepinephrine and Epinephrine

– Catecholamines released by nerves in the sympathetic branch of the ANS

• Dopamine

– Involved in the coordination of impulses and responses


Neurotransmitters (cont.)Neurotransmitters (cont.)

• Gamma-aminobutyric Acid (GABA)

– Inhibits nerve activity and is important in preventing over-excitability or stimulation such as seizure activity

• Serotonin

– Important in arousal and sleep and in preventing depression and promoting motivation


Central Nervous SystemCentral Nervous System

• Made up of brain and spinal cord

• Structures are covered by meninges

• Blood brain barrier

• Blood supply to the brain


Anatomy of the BrainAnatomy of the Brain


HindbrainHindbrain

• Runs from the top of the spinal cord into the midbrain

• Most primitive part of the brain - contains the brainstem

• Controls basic vital functions:

– Breathing

– Blood pressure

– Swallowing

– RAS


MidbrainMidbrain

• Contains the thalamus, the hypothalamus, and the limbic system

• The thalamus sends direct information into the cerebrum to transfer sensations

• Hypothalamus acts as major sensor activity in the body

– Temperature regulation

– Water balance

– Appetite

– Endocrine function


Limbic SystemLimbic System

• Contains high levels of neurotransmitters

– Epinephrine

– Norepinephrine

– Serotonin

• Controls expression of emotions


ForebrainForebrain

• Made up of two cerebral hemispheres joined together by the corpus callosum

• Receives and sends nerve impulses, coordinates speech and communication, and facilitates learning


Spinal CordSpinal Cord

• Made up of 31 pairs of spinal nerves

• Each spinal nerve has two components or roots

– Sensory fiber (dorsal root)

• Brings information into the CNS from the periphery

– Motor fiber (ventral root)

• Causes movement or reaction


Function of Central Nervous SystemFunction of Central Nervous System

• Sensory Functions

• Motor Functions

• Intellectual and Emotional Functions


Intellectual and Emotional FunctionIntellectual and Emotional Function

• Two hemispheres of the brain process information differently

• Right Side

– Artistic

• Left Side

– Analytical

• When learning takes place and actual change occurs in a neuron


Intellectual and Emotional Function (cont.)Intellectual and Emotional Function (cont.)

• Some degree of stress helps facilitate learning

• Increased stress inhibits learning

• The limbic system plays a role in learning

• Emotions associated with memory as well as the present, have an impact on stimulus response

• The placebo effect is a documented effect of the mind on drug therapy: If a person perceives that a drug will be effective, it is much more likely to actually be effective


QuestionQuestion

Which of the following documented phenomena may occur as a result of drug therapy?

A. Action potential

B. Placebo effect

C. Expectation effect

D. Learning


AnswerAnswer

B. Placebo effect

Rationale: The placebo effect is a documented effect of the mind on drug therapy: If a person perceives that a drug will be effective, it is much more likely to actually be effective.

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Ppt chapter 19