Slap Hands Game!

In the slap hands game, if your hands were on top what did you have to respond to?

Stimulus - any internal or external change or event that causes a response in an organism http://www.livescience.com/33700-bulls-charge-red.html

In the slap hands game, what body structures allowed you to detect and respond to the stimulus? Sense organs (eyes, skin) Nerves Brain Muscle

The Human Nervous System

What are some examples of stimuli that an organism might have to respond to? External Predator Prey Food, Water Mates, Rivals Sunlight Temperature Internal Hunger Full bladder Full rectum Blood sugar level Infection Temperature

Why is it important to be able to respond to stimuli? Survival Homeostasis - the maintenance of a stable internal environment in an organism

To maintain homeostasis, the activities performed by various structures have to be controlled and coordinated. Regulation - the coordination and control of all the life activities

How does our nervous system function? (How do nerve cells work?)

Neuron - the basic structural and functional unit of the nervous system Specialized cell for receiving and transmitting impulses (stimuli)

The Neuron Axon Axon Terminal Branches

1 - Soma (cell body) 5 - Node 2 - Axon 6 - Dendrites 3 - Myelin Sheath 8. 1 - Soma (cell body) 5 - Node 2 - Axon 6 - Dendrites 3 - Myelin Sheath 7 - Nucleus 4 - Axon 8 - Terminal Branches

Describe the direction in which impulses (stimuli) are transmitted along a neuron.

2. What is a synapse? - the space between two neurons Synapse

How do neurons receive and send impulses? (How do nerve cells work?)

Sodium ions are like Black Friday shoppers The membrane of a neuron (its dendrite) before the stimulus is polarized Sodium ions are like Black Friday shoppers

Stimulus opens ion channels Outside cell Inside cell

What happened to the charges? Membrane is depolarized Before Stimulus After Stimulus

How does a nerve impulse travel down the neuron?

axon

Krazy George Henderson A High School teacher Became a professional cheerleader 1st time was an accident delayed response of one section to his direction

Nerve impulse - a moving area of electrical and chemical change on the nerve cell membrane

The Myelin Sheath

Saltatory conduction - (leaping) - influx of ions in one node causes next node to become permeable to sodium (sodium channels open)

Speed of a Nerve Impulse unmyelinated myelinated axons axons 3 mm/sec 200 M/sec (200,000mm/sec)

How does the nerve impulse get across the space between neurons? Synapse (the space between two neurons)

Animation of Synaptic Transmission http://www.youtube.com/watch?v=HXx9qlJetSU&feature=related

3. What is the chemical substance that transmits impulses across the synapse called? neurotransmitters

A Neuromuscular Junction Neurotransmitter Receptors

Slap Hands Activity

How does the nerve reset itself so it can fire another impulse?

The Sodium-Potassium Pump

acetylcholinesterase

Sarin Nerve Gas Sarin nerve gas inhibits the activity of an enzyme that is supposed to break down the neurotransmitter acetylcholine. This neurotransmitter makes skeletal muscles contract. Acetylcholine also acts at sites made of smooth muscle (the iris, respiratory and gastrointestinal tract, bladder, and blood vessels), cardiac muscle, as well as the salivary and sweat glands.   Predict what would happen to the concentration of acetylcholine in the synapse and on postsynaptic receptors as a result of exposure to Sarin. Predict the effects of Sarin on the body.

Immediate signs and symptoms of sarin exposure Runny nose Watery eyes Small, pinpoint pupils Eye pain Blurred vision Drooling and excessive sweating Cough Chest tightness Rapid breathing Diarrhea  Nausea, vomiting, and/or abdominal pain Increased urination Confusion Drowsiness Weakness Headache Slow or fast heart rate Low or high blood pressure

Cyanide Cyanide is a fast-acting poison that can be lethal. In large doses, cyanide quickly binds with iron in cytochrome a3, a protein in the mitochondria essential for the process of aerobic cellular respiration.   Predict the effect of cyanide on ATP production and the kind of cellular respiration taking place in cells. Predict the effect of cyanide on nerve cell activity (e.g. sodium- potassium pump; impulses traveling down the axon).

Synapse - space between two neurons synaptic knobs - secrete neurotransmitters into the synapse Neurotransmitters - chemicals that transmit impulses across a synapse

Myelin sheath - wraps around axon insulates axon

The Neuron

Nerve Impulse 1. sodium ions (Na+) flow into the cell 2. Inside of cell becomes positively charged 3. This change stimulates adjacent membrane to become permeable to sodium 4. More sodium flows into the cell in this adjacent area of membrane (step 1) 5. Repeat step 2 etc...

+++++++ - - - - - - - - - - ++++++++ outside neuron +++++++ - - - - - - - - - - ++++++++ __________________________________________________________________ - - - - - - - +++++++++++ - - - - - - - - inside neuron impulse +++++++ - - - - - - - - - ++++++++

What structures on the membranes of our cells detect (receive) stimuli? Receptors - structures specialized to detect stimuli

Dendrites - receive stimuli (impulse) and conducts impulse to cell body, cyton (cell body) in a sensory neuron, the impulse comes from a stimulus

Axon - transmits or conducts impulses away from cell body toward terminal branches Terminal branches - conducts impulses to different synaptic knobs and then to different cells