The Nervous System & Senses

Read “The Central Nervous System” and “The Peripheral Nervous System”

Anatomy of a Neuron Dendrites – receive signals coming to cell body

Anatomy of a Neuron Axon – long thin fiber that carries signals from cell body

Anatomy of a Neuron Synaptic Terminals – where neuron communicates with another cell

Watch “The Chemical Mind” to review what a neuron is and how nerve impulses travel.

How Are Signals Transported Along Neuron?

By using concentration gradients of charged particles!

Watch “Action Potential” if you want to learn more about how neurons work.

How does signal from neuron pass to next neuron or another cell?

Synapse - area where cell to cell signal transmission occurs

Watch “Synapses” if you want to learn more.

Neurotransmitters, Drugs & Addiction

Normal: after neuron releases NT, it starts to pump it back in (limits effect)

Cocaine: blocks pump = effects are enhanced

Neuron decreases number of receptors

Now higher levels of NT required for user to feel normal

W/o drug, neurons are inadequately stimulated

Experiences emotional crash relieved by more drug

Neurotransmitters, Alcohol & Addiction

Alcohol stimulates receptors for GABA. What will be the effects of this?

This enhances inhibitory signals & blocks receptors for glutamate which reduces excitatory signals

If one drinks frequently what happens to number of receptors?

Brain decreases GABA receptors & increases glutamate receptors

If a one drinks frequently what happens to number of receptors?

Brain decreases GABA receptors & increases glutamate receptors

How will that make you feel?

Nervous System Uses Many Different Neurotransmitters

What are the effects of caffeine and nicotine on neurotransmitters?

Neurotransmitters & Depression

What effect does too little serotonin have on body?

Too little serotonin causes depression

How do anti-depressants work?

Antidepressants block reuptake of serotonin.

Will this increase or decrease serotonin’s effects?

Antidepressants block reuptake of serotonin.

Will this increase or decrease serotonin’s effects?

How do anti-depressants work?

Chemicals can affect how your neurotransmitters work in your brain!

Mouse Party: Take a look inside the brains of mice on drugs

Read about the “Brain”

The Limbic System

Stroke Victim

Strong evidence that hippocampus is involved in learning and memory

Temporal lobes seem to be important in the retrieval of long term memories

Mental illness & personality may be attributed to brain structure

Mental illness & personality may be attributed to brain structure

Now watch “Getting to Know Your Brain”

Watch the online video “Sleep” to learn about what your brain is doing while you sleep.

Watch “Why Do We Have to Sleep” to learn more about the science of sleep.

What does our spinal cord do for us?

A communication center of its own, with no input from the brain.

Major pathway for sensory impulses going to and from the brain.

ReflexesAre they automatic?

Why do we have them?

Reflex Arc: sensory neuron directly linked to motor neuron = quick response

How is response so fast & automatic?

Is brain involved?

Sensory Receptors:

Receives stimuli from environ. & produce electrical responses that brain can understand.

How do our senses work?

How do we detect temp., pain, & pressure?

How do we detect temp., pain, & pressure?

How do we detect chemicals?

How do we detect chemicals? Smell (Olfaction):

Taste:

Each taste bud has many taste receptors

How do we detect chemicals?

Taste & Smell

Molecules released from food move up through throat where smell receptors are.

Watch “Taste and Smell” if you want to learn more.

How do we detect sound?What do sounds produce?

What type of cells detect this?

How do we detect sound? The ear captures, transmits & converts sound into electric signals

Watch “Hearing and Balance” if you want to learn more

Vibrations bend hair cells.

Hair cells release neurotransmitters onto auditory nerves which lead to brain.

Anything over 85 decibels can damage hearing

How do we detect light?

How is light detected? Eye collects, focuses & translates light waves so that brain can understand them

Read “Vision”

How Lens Focuses Light

How Lens Focuses Light How does the shape of your lens change when you are viewing a nearby versus far away object?

Nearsightedness – cannot focus on distant objects

If you are nearsighted, how is your eye shaped?

Farsightedness – cannot focus on objects that are close up

If you are farsigted, how is your eye shaped?

Astigmatism – blurred vision caused by misshapen lens or cornea

Why the human eye is not perfect

What causes our blind spot?

Blind Spot

What causes glowing eyes of animals at night?

Modified choroid that reflects light back onto the retina rather than absorb it, this maximizes the animals ability to see in dim light.

Tapetum Lucidum

Watch “Vision” if you want to learn more.