9.1 Vertebrate Nervous System

• 2 Main Divisions: CNS and PNS CNS: Central Nervous System

the bodies coordinating centre for mechanical and chemical actions. Brain and Spinal Cord

PNS : Peripheral Nervous System all parts of the nervous system (excluding brain and

spinal cord) that relay information between the CNS and other parts of body . Not covered in bone.Has 2 divisions: Autonomic and Somatic

DIVISIONS of the NERVOUS SYSTEM

SOMATIC NERVES

• Voluntary control• Skeletal muscle, bones, skin

• Sensory somatic nerves relay info. About the environment to the CNS

• Motor somatic nerves initiate a response

AUTONOMIC NERVES

Special motor nerves that control the internal organs of the body

Has 2 Divisions: Sympathetic and Parasympathetic

Sympathetic: stimulatory, prepares body for stressParasympathetic: calming, returns body to normal

Together they operate as “on-off” switches

Neuron –Nerve Cell

• 2 difft. types of cells exist in NS.: Glial & Neurons

• Glial: nonconducting, structure support and metabolism role

• Neurons: functional units of NS (3 categories)– Sensory Neurons (afferent)– Motor Neurons (efferent)– Interneurons: link neurons within body,primarily in brain

and s cord. Integrate and interpret sensory info. Connect neurons to outgoing motor neurons.

Sensory neurons

• Carry impulses from sensory receptors to CNS• Ex eye photoreceptors,nose tongue chemoreceptors• Relay in clusters called ganglia outside of the sp. Cord

Motor and Sensory Neuron

Motor Neurons

• Carry impulses from CNS to effectors– Muscles, organs, glands

STRUCTURE of a NEURON

NERVE

Axonal Bouton-Terminal

Neuron Structure

• Cell Body (soma): Receives,processes and coordinates info

Axon: carries nerve impulses away from cell body Dendrites: Carry impulses, info to the cell bodyMyelin Sheath: insulated covering over axonNodes of Ranvier: gaps in myelin along axonSchwann Cells: glial cells that produce myelinBouton: end of axon, contains neurotransmittersNeurilemna: membrane surrounding some axons, promotes

regeneration of SOME damaged neurons, not grey matter

REFLEX ARC

SUMMARY

HOMEWORK

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