The Nervous and Digestive systems.

The concept of wellness.◦ The fact that you have control over your life and health.

How stress impacts your body and health.◦ You may not be able to change the stressor, but you may

be able to modify your stress response!

Remember, during the stress lecture, there was a relationship between your nervous system and stress?◦ We will now learn the basics about your nervous system.

◦ After that, we will look at your basic digestive system, which will lead us to nutrition!

What have we learned so far?

Your body is very big, and very complicated.◦ Basically speaking, your nervous system allows your

body to communicate with nature, and with itself.

When you feel a hot stove with your hand, your nerves alert your brain to pull your hand away. This prevents further injury.◦ Pain is actually a good thing.

What is your nervous system, and what is it for?

Your brain is the control center for your body. Imagine your brain as your

bodies computer.

This computer is connected to a network.

The centralized processing takes place in your brain and spinal cord.

Your brain and spinal cord communicate with your body through a series of nerves.

How do the CNS and PNS relate to one another? Central NS

◦ Brain; spinal cord. Peripheral NS

◦ Nerves leading to body.

Notice that your CNS tells your body what to do.◦ But your body gives your

CNS the information it needs to make these decisions.

Frontal, parietal, temporal, occipital

These names correspond to regions of your brain.

Get to know the basic functions of the regions in your brain!

But where your brain really begins is deep inside… Remember the

hypothalamus?◦ It rests deep inside of your

brain.◦ The “control center” of the

brain.◦ Controls the endocrine

system.◦ Maintains homeostasis.

Thalamus◦ Your brains “relay center.”◦ It coordinates information.

These are called the “primitive” parts of your brain, associated with the basic functions of your body.

The thalamus and hypothalamus are part of your limbic system. Why do you think

your limbic system is important?

What does your limbic system affect?

Compare the limbic system with the frontal lobe (cortex).

What do these areas of the brain do?◦ How do these areas

conflict with the limbic system?

◦ What are examples of this conflict?

◦ Can this explain some social behavioral issues?

Pretty interesting stuff.

As you move farther from the “primitive” brain, more layers are added.

Each area has specific functions.◦ This gives increased

complexity to the human brain.

The human brain is considered far more complex than any possible computer.

What about the spine?

It is also very complicated.◦ It is part of the CNS.◦ It conducts information

from the body to the brain, and vice versa.

It rests inside of your backbone.

It also can “make decisions” on its own.

Be able to compare the central nervous system to the peripheral nervous system.

Describe the four basic external areas of the brain, and what they are associated with.

Compare the thalamus to the hypothalamus.

Be able to describe the limbic system, and how it may “conflict” with the frontal cortex.

What do you need to know so far?

Your brain and spinal cord are filled with nerve cells.

These nerve cells have arms that connect them to other areas, and are able to process information.

They are also the link between your nervous system and your body.

Here is a basic nerve cell, called a neuron. The basic cell is housed

within the cell body.

Dendrite◦ Brings information to

nerve cell. Axon

◦ Takes information away from nerve cell.

◦ Surrounded by a myelin sheath.

Synapse◦ Junction between two

neurons, or a neuron and a cell.

Imagine touching a rose thorn. You have dendrites in

your fingers, which detect pain.

You send a signal to your spine.

Your spine tells your arm muscles to contract.

You pull your hand away from the rose.

How does this happen?

Your nerves need to communicate with your body.

In this case:◦ The nerves to your

muscles rest beside the muscle fibers.

◦ They cause an electrical impulse to go into your muscle.

◦ This impulse causes your muscle to contract.

Up close and personal.The neuro-muscular junction.

The nerve sends the “contract” signal to the muscle.

This message is spread across the muscle fiber.◦ This causes the

muscle to contract.

More close, and more personal.

This is the connection between your nervous system, and your body.

This is a synaptic cleft, and is very important.

The synaptic cleft is where chemicals cause reactions.

Notice that the axon does not actually touch the target structure.

Since it does not touch it, it must send a signal.◦ This signal is called a

neurotransmitter.◦ It “transmits” a signal

from a neuron.

Ever heard of “nature versus nurture”?◦ Is your personality based on your genes, are is it

based on your choices.◦ If it is based on your genes, then your genes control

which chemicals your body produces.◦ These chemicals dictate how your body acts.

Think about how drugs (legal and illegal) relate to this synaptic cleft.

These neurotransmitters are the key.

The basic structure of the nerve cell (called a neuron).◦ Dendrite, axon, synapse.

Be able to describe what basically happens if you injure your hand.

Describe the neuro-muscular junction.

How do nerves communicate to one another, or to your body?◦ Describe the synapse.

Now what do you need to know?

Make sure you look carefully at the information I have presented.◦ Most of this is not in your text.◦ This is the information I want you to know!◦ Be sure to ask questions in lecture!

Now we can begin the Digestive System!

That does it for the nervous system!

What could the digestive system possibly be used for?

It has many parts, but one basic function.◦ To provide nutrients

and energy to your body.

We will take a tour from start to finish!

Here is the basic pathway of food.

The digestive system has a lot of “space” which needs to be organized.

Try to follow the line from the stomach, to the small intestine.◦ Notice that it goes

downwards.

Then the large intestine moves up, then across, then back down.

Lots of surface area!

Lets begin in your mouth. Your mouth grabs food,

chews it, mixes it with saliva, and gets it ready to swallow.

You have four basic tooth types:◦ Incisors◦ Canines◦ Premolars◦ Molars

These help you to break large food particles into smaller ones.◦ Mastication = chewing.

Open wide!Can you tell which is which?

Incisors◦ Your two front teeth.◦ These bite into your food.

Canines◦ The first tooth after the incisors.◦ These help rip your food –

especially if you are a vampire! Premolars

◦ The next two teeth – for crushing.

Molars◦ The last three teeth.◦ The main crushers and grinders.

“Wisdom teeth”?◦ Can you see them on the top

jaw? Salivary glands

Basic tooth structure.

As many of you know, your teeth have many nerves (which can cause pain).◦ Imbedded into your jaw.◦ Surrounded by gums.

But, your tooth is bone surrounded by enamel.◦ This is not bone.◦ Enamel is very hard.

Your tongue.

Helps you to move food around in your mouth.

Salivary glands◦ Secretes saliva.◦ Helps in digestion.

Sensory nerves◦ Bitter◦ Sour◦ Salty/sweet◦ Umami (savory-meat)

Now that you have chewed your food, what next?

Perhaps you should swallow?◦ This is called

“Deglutition.”

Your esophagus connects your mouth to your stomach.◦ You push food through

your esophagus.

Your stomach.

Very strong storage organ.

Secretes many digestive enzymes and acids.

When it passes into the small intestine, it is ready for absorption.

Here is how your stomach sits in relation to other organs.

Notice that it sits between your liver and your pancreas.

You have a lot of organs in a small space, so they are packed together.

When food passes into your small intestine, it goes into the duodenum. Your small intestine

has three parts, and the duodenum is the first.◦ It receives pancreatic

enzymes and bile.◦ These help food to

become more easily absorbed.

When food goes into your small intestine, it is ready to be absorbed.

Your small intestine has a lot of surface area.

The word “villus” or “villi” refer to many small projections from small folds of tissue.

These villi are like hairs, that give you more surface area to absorb food particles.

The more surface area you have, the more food can be absorbed.

Once food goes through your SI, it passes into your large intestine. Your large intestine

mainly is responsible for:◦ Reabsorbing water◦ Absorbing salt

Once the digested material reaches the end of the large intestine, it is ready to be expelled from your body as feces.◦ Most of what is in feces

is indigestible.◦ Although there is still

things that could be digested, just not in you.

Parts and functions of the digestive system:◦ Mouth, stomach, small intestine, large intestine.

Can you describe what would happen to a piece of food if you were to eat it?

So what do you need to know?

Again, this may seem like a lot of information, but it really isn’t.

I hope that you realize that I am keeping this somewhat simple, hoping to spark some interest, and get some interesting questions!

Let me know if you need any help.

That is it!