The Nervous System & operation

The mind is a terrible thing to waste.

Central Nervous System

• Brain & Spinal Cord– Made of Association

neurons (Interneuron) –integrate messages

Peripheral nervous system• Made of nerves outside

the central nervous system

• Receptor neurons -receive stimuli

• Sensory neurons -send impulses along the sensory neurons to the brain or spinal cord.

• Motor neurons - send impulses from the brain to muscles or glands.

Basic unit of the nervous system

• Neuron - its parts and functions

• Cell body• Axon• Dendrite• Myelin sheath• Axon terminal buttons

Different Neurons have a different threshold (critical level)

• Once the neuron reached its critical level it fires all of the way.

Impulse Transmission down a Neuron

• Electrochemical change in membrane permeability to sodium ions

• Resting-polarized

• Depolarized-stimulated

• Repolarized- sodium pump out

Synapse operation• Neurotransmitters are

chemicals that are released into the synapse

• Ex. Acetylcholine is released by the Axon and stimulated the dendrite to become permeable to sodium.

• Cholinesterase is the enzyme that destroys Acetylcholine.

Reflex Arc• The impulse

travels only as far as the spinal cord then to the motor neuron contracting a muscle

Nerve pathway

Nerve toxins• These chemicals bind to synapse enzymes and inhibit their function-what is the result?

Man Arrested Planning To Lick Hallucinogenic Toad 6:09pm UK, Thursday November 15, 2007

A man in Missouri has been arrested for possession of a hallucinogenic toad.Police in Kansas City say David Theiss planned to get high by licking the Colorado River Toad's venom glands.

                                             

Far out: a Colorado river toadThe 21-year-old is accused of possessing the toad "with the intention of using it as a hallucinogen".They said that many pet shops in the area do not stock the animal because the venom can make people sick and can kill household pets.Animal expert Danny Snyder told US station KMBC: "People used to do it all the time but it got faded out awhile, but came back as a fad. Not a smart one."Authorities in Clay County said it was the first time they had dealt with such a drugs bust.Theiss was released on bail.The toad was kept in custody at a police crime lab, authorities said.

Brain –protective covering• Meninges three layers

that provide protection and nutrition to the brain

• Outer- dura mater• Middle- Arachnoid

mater• Inner- pia mater

• Cerebrospinal fluid- shock absorber

Brain parts and functions

• Cerebrum -85% of the brain’s weight-thinking, memorizing, decision making

• Cerebral cortex- voluntary movements , intelligence, sensory areas- interprets

Cerebellum

• Coordinated motor activity and balance

Medulla oblongata

• Brain stem- controls vital functions– Respiration– Heart rate– Blood pressure

Brain parts and functions

• Thalamus sends sensory impulses to the brain

• Hypothalamus- controls thirst, hunger, pleasure center, behavior, digestion. “Master gland” (electrical & chemical)

Autonomic Nervous System• Involuntary –can’t

control• Sympathetic NS-

used in times of stress- accelerator

• Parasympathetic NS –used to bring the system back to a peaceful state

QUESTIONS (checking for understanding)

• Explain what would happen if the sodium pumps were poisoned.

• What does ‘all or nothing’ mean?

• Know the Neuron - its parts and functions

QUESTIONS (checking for understanding)

• Name the types of neurons that are in the human body. What is the function of each type?

• How does a simple reflex arc work?

• What is true of a “resting” potential?

• What is the function of Schwann cells and electrical synapses?

QUESTIONS (checking for understanding)

• How would you describe a nerve impulse?

• Where are vesicles that contain neurotransmitters located?

• In which direction do sodium pumps, pump sodium?

• How does the Somatic differ from the Autonomic nervous system?

QUESTIONS (checking for understanding)

• Describe the function of the following brain structures:– Cerebrum– Cerebellum– Medulla Oblongata– Hypothalamus

• Name the three parts of the meninges and give the function of each.