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 Nucleus Axon terminals Cell body Myelin sheath Axon Nodes 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 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.

Figure 35-6 Resting Potential Section 35-2

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

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 Section 35-2

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.

Dendrite of adjacent neuron Figure 35-8 The Synapse Section 35-2 Direction of Impulse Dendrite of adjacent neuron Axon Receptor Vesicle Axon terminal Synaptic cleft Neurotransmitter

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.

Cerebrum, cerebellum, brain stem Section 35-3 Cerebrum, cerebellum, brain stem Pons Pituitary gland Hypothalamus Cerebrum Medulla oblongata Spinal cord Cerebellum Pineal gland Thalamus

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 canal Gray 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