DO NOW

The body is organized with different levels, the smallest are called cells. Name the next three

Tissues, organs , organ systems

Name two functions of the nervous system.

Neuron

Cells that transmit messages carried by the nervous system.

Neuron

Axon terminals

Myelin sheath

Nodes

Cell body

Axon

Nucleus

Dendrites

Impulse

http://science.nhmccd.edu/BioL/ap1int.htm

Nerve Impulse Resting Neuron: outside of cell has

net positive charge inside has net negative charge.

Where does this difference come from?

The Cell membrane has a Na+ / K+ pump. This pump maintains the Resting Potential Sodium/potassium pump sits on the

membrane of the neuron and uses energy to pump Na+ out of the cell and K+ into the cell.

Section 35-2

Figure 35-6 Resting Potential

Moving Impulse

Once a stimulus is received it causes a movement of ions across the membrane – the Nerve Impulse

Section 35-2

Figure 35-7 An Impulse

Section 35-2

Figure 35-7 An Impulse

Section 35-2

Figure 35-7 An Impulse

Section 35-2

Figure 35-7 An Impulse

action potential

Cell Membrane of Neuron

Contains thousands of protein channels letting the ions through.

Changing the charge of the inside of the neuron from negative to positive is called the action potential.

Review

Define Neuron Nerve Impulse Cell Membrane of Neuron

Nerve impulses are ALL or NOTHING

Threshold a minimum level that the nerve need to transmit an impulse.

Synapse

The location where Axon Terminals of a nerve cell can transfer the nerve impulse to the dendrites of another cell.

Vesicle

Axon

Axon terminal

Synaptic cleft

Neurotransmitter

Receptor

Dendrite of adjacent neuron

Direction of Impulse

Section 35-2

Figure 35-8 The Synapse

Neurotransmitters

Chemicals used by a neuron to transmit an impulse from one nerve to another

resting potential

Central Nervous System

The CNS consists of the Brain and the Spinal cord

BRAIN – mass 1.4 kg/ 100billion neurons

Cerebrum – responsible for the voluntary or conscious activities of the body

Contains folds and grooves has four lobes – frontal, temporal, parietal, occipital

Outer layer is called cerebral cortex and is made of gray matter-cell bodies

Inner layer is white matter – axons and myelin sheaths.

Pons

Pituitary gland

Hypothalamus

Cerebrum

Medulla oblongata Spinal cord

Cerebellum

Pineal gland

Thalamus

Section 35-3

Cerebrum, cerebellum, brain stem

Brain - Cerebellum

Second largest region of the brain, coordinates and balances the actions of the muscles so that the body can move without falling and efficiently,

Brain – The Brain Stem

Connects brain and spinal cord. Has two regions the pons and the medulla oblongata. Blood pressure, heart rate, breathing, and swallowing are controlled here.

Brain – thalamus and hypothalamus

Thalamus – receives messages from all sensory organs and relays it to the cerebrum.

Hypothalamus – control center for recognition of hunger, thirst, fatigue, anger, and body temp.

human brain cross section

Spinal Cord

Humans have 31 pairs of spinal nerves Some nerve impulses are processed in

the spinal cord – reflex

Reflex- quick automatic response to a stimulus- allowing you to respond to danger immediately.

Spinal cord

Spinal nerve

Central canalGray matter

White matter

Meninges

Peripheral Nervous System

Consists of all nerves and cells that aren’t part of the CNS including the cranial nerves.

Divided into sensory division and motor division.

Senses

Visual System – we are able to see because light enters the eye through the cornea, the image is focused with the lens and travels across vitreous humor fluid to rest upon the rods and cones of the retnia

Photoreceptors

Rods are responsible for light sensitivity –

Cones are able to differentiate colors.

Cow Eye Dissection

http://www.exploratorium.edu/learning_studio/cow_eye/step01.html

Hearing and Balance

Hearing

We hear because mechanical energy - from vibrations are converted into neuronal messages through the cochlear nerve.

Balance

The Ear contains structures that help the body maintain balance – called the semicircular canals.

Smell and taste

The nasal cavity contains chemoreceptors to detect chemical

Sense of taste is often confused with sense of smell

Taste is also a chemical sense, taste buds detect chemical changes- salty, bitter, sweet and sour.

Touch

The amount of sensory receptors on the skin varies with fingers, toes and face.

DRUGS - that effect the synapse

Stimulants – increases the actions regulated by the nervous system, blood pressure, breathing rate,

Depressants – decrease heart rate, breathing rate, lower blood pressure, relax muscles

Opiates – mimic endorphins – naturally occurring brain chemicals to lessen pain.

drugs

Marijuana – bad for the lungs, long term use can lead to memory loss, decreased ability to concentrate, and infertility in males.

Alcohol – a depressant that slows down the rate the CNS functions- alcoholism and destruction of liver