Chapter 35 “The Nervous System” 35.1 “The Human Nervous System”35.1 “The Human Nervous System” Objective:Objective: –List the 3 main structures of a neuron –Describe a Nerve Impulse

Neurons Basic unit of the N.S.Basic unit of the N.S. Carry messages in the form of electrical impulsesCarry messages in the form of electrical impulses Made up of:Made up of: –cell body - largest part –dendrites - carry impulses toward the cell body –axon - carries impulse away from cell body –axon terminal – sends impulse to next neuron

Three Types of Neurons 1.Sensory : body to brain 2.Motor : brain to body 3.Interneurons : connect sensory & motor neurons in brain and spinal cord

Nerve Impulse Begins when a neuron is stimulated by env. or another neuronBegins when a neuron is stimulated by env. or another neuron Resting Potential: a neuron without an impulseResting Potential: a neuron without an impulse –Inside of neuron is more negative than outside Action Potential: change in chargeAction Potential: change in charge –Inside of neuron becomes more positive

Inside is negative Inside becomes positive Domino effect passes action potential down axon Inside returns to negative Resting Potential

Myelin Myelin sheath: fatty layer which insulates axonMyelin sheath: fatty layer which insulates axon Speeds up impulseSpeeds up impulse

Synapse Synapse: The space between the axon terminal of one neuron and the dendrites of the next neuron.Synapse: The space between the axon terminal of one neuron and the dendrites of the next neuron. Axon terminal releases neurotransmitters.Axon terminal releases neurotransmitters.

35.2 “Organization of the N.S” Objective:Objective: –Distinguish between the Central Nervous System & the Peripheral Nervous System.

The Central Nervous System BrainBrain Spinal CordSpinal Cord

The Brain Four lobes, two halvesFour lobes, two halves Major regions:Major regions: –Cerebrum – conscious activity/thought –Cerebellum – coordinates movement –Brain stem – connect brain and spinal cord, controls many involuntary fxns –Thalamus – receives sensory messages –Hypothalamus – controls primitive needs and emotions

The Brain

The Spinal Cord 31 pairs of nerves branch off31 pairs of nerves branch off Controls reflex arc Controls reflex arc

Peripheral Nervous System All nerves outside of brain and spinal cordAll nerves outside of brain and spinal cord Sensory – receives internal and external stumuliSensory – receives internal and external stumuli Motor – controls muscles and glandsMotor – controls muscles and glands

Motor DivisionMotor Division –Somatic NS – controls all voluntary activity –Autonomic NS – involuntary activity Sympathetic – controls body during times of stressSympathetic – controls body during times of stress –Ex - speeds up heart rate Parasympathetic – controls body normally, returns body to normal state after stressParasympathetic – controls body normally, returns body to normal state after stress –Ex – slows heart rate Peripheral Nervous System

N.S. Concept Map

Chapter 35.3 “The Senses” Objective:Objective: –List and discuss the 5 senses.

The Five Senses Sight, Sound, Taste, Touch, SmellSight, Sound, Taste, Touch, Smell There are 5 general categories of sense receptors.There are 5 general categories of sense receptors. –Pain receptors –Thermoreceptors - temperature –Mechanoreceptors – touch, sound –Chemoreceptors - chemicals –Photoreceptors - light

Vision Photoreceptors in retinaPhotoreceptors in retina –Rods – detect light –Cones – detect color

Hearing Acoustic Receptors: a special type of mechanoreceptor.Acoustic Receptors: a special type of mechanoreceptor. –Respond to sound (disturbance of air) –Found in inner ear. Semicircular canals: fluid filled tubes that help you maintain your balanceSemicircular canals: fluid filled tubes that help you maintain your balance

The Ear Semicircular canals

Smell & Taste ChemoreceptorsChemoreceptors –Respond to taste & smell (chemical stimuli) Found in tongue, roof of mouth, nasal cavity.Found in tongue, roof of mouth, nasal cavity.