Homeostasis in Your Body

So far this year, we have studied DNA and genetics, evolution, and cells. Now we want to see how these things come together to make this wonderful being we call “Y-O-U”!

You already know that DNA is your blueprint. (Remember hamburger boy?) Now let’s see how that blueprint creates your body.

DNA will tell you cell what it has to make according to its job. What are some things that cells have to make?

Levels of Organization

Your body is made of a hierarchy. A what?

A hierarchy. You know, something that gets bigger and bigger as it goes up – like the classification system.

Oh yeah!Anyway, your body starts off with small pieces

and uses those pieces to make larger pieces. Then it uses those large pieces to make huge pieces. This process keeps going until we create your body. In fact, this process keeps going until we include all organisms on the Earth.

Going beyond cells

Okay, let’s start one of the most important things you can do for your body…….

That’s nice, but what about me?

EAT!!!!!

Food is taken in through your digestive system.

The digestive system accomplishes two tasks: digestion (the breakdown of food) and absorption (getting the food into your blood stream).

The first half of your digestive system is responsible for digestion; the second half is responsible for absorption.

Intake of food

There are two kinds of digestion that occur in your body:

Mechanical digestionThis is the physical breakdown of your food. Every time

you chew or a muscle crushes the food, it is going through mechanical digestion.

Can you think of some places where mechanical digestion happens?

Chemical digestionThis is the chemical breakdown of your food. Every time

your body adds a chemical to the food, it is going through chemical digestion.

Can you think of some places where chemical digestion happens?

Types of digestion

Food moves through a process called peristalsis. Peristalsis is the movement of muscles that push the food along. Click below to see how this works:

Peristalsis video

How does food move through your body?

Digestion

MouthEsophagus

Stomach

Mechanical and Chemical Digestion takes place here. Amylase is released here.

Tube that leads to the stomach, made of muscle.

Food is liquefied here by action of muscles and acids. Pepsin is released here.

Absorption

Small IntestineLarge Intestine

Rectum

Anus

The large intestine is responsible for absorbing water.

Waste products are stored here until you defecate.

Nutrients are absorbed in the villi in the small intestine. Bile is released here.

Feces (wastes) pass through the anus to leave the body.

VilliVilli are used to absorb the nutrients from your food.

Accessory OrgansAccessory organs produce chemicals that help your body break down materials.Salivary glands found in

your mouth produce amylase to help digest carbohydrates.

Pepsin is produced in your stomach and it breaks down proteins.

The liver produces bile to help you digest lipids and is stored in the gall bladder.

The pancreas produces insulin that helps to regulate your blood sugar levels.

Let’s Review: What happens in the digestive system?

Nutrients (Organic molecules, vitamins, minerals, water) are distributed through the body by the circulatory system.

What organic molecules can you remember?There were four of them!!!

The circulatory system is made of blood, blood vessels and the heart and its job is to circulate oxygen, food and wastes.

Blood carries red and white blood cells, platelets, and nutrients in a fluid called plasma.

Blood circulates through the blood vessels when the heart beats.

Distribution of Nutrients

HeartThe heart is made of

cardiac muscle which is involuntary, or under the control of your brain.

The atria accept blood and the ventricles pump the blood which is why they are larger.

Each section of the heart is closed off by a valve that keeps the blood from flowing backwards.

Blood can only flow one way through your body. Think about what would happen if it could go forwards and backwards at the same time.

If you can’t imagine it, think about what happens when you try to walk down the wrong side of the hallway. How far do you get?

Now, if you were a red blood cell going the wrong way, could you make it to drop off your oxygen in time?????

Why do you need valves?

There are three main vessels in your body: arteries, veins, capillaries.

When they leave your heart, arteries branch into smaller vessels called arterioles. Arterioles branch into smaller vessels called capillaries in your organs. On the way back to your heart, capillaries collect to form venules and venules collect to form veins.

The system looks like this:

Blood Vessels

Heart Arterie

s

Arterioles

Capillaries

Venules

Veins

Blood VesselsArteries are made of

muscle tissue and are very thick to withstand the pressure put on them when the heart beats.

Veins are not as thick, but contain valves to keep the blood flowing back to the heart.

Capillaries are only one cell thick to allow for diffusion and osmosis to occur.

What was that again?

Blood flow in the heartRemember that blood

only flows one way through the heart. This allows the blood to always move forward.

To enter the heart, the blood comes in through the atrium.

The blood passes through a valve and enters the ventricle. Then, it leaves the heart after the ventricle.

Your heart is separated into two main parts: the right side and the left side. Notice that they are two different colors.

The right side of your heart carries deoxygenated blood from your body to lungs.

The left side of your heart carries oxygenated blood from your lungs to your body.

Blood flow in the heart

How does your heart get blood?Your heart has its own

blood supply called the coronary arteries and veins. These vessels give the blood oxygen and take away carbon dioxide like your other organs.

The coronary arteries and veins attach to the aorta and vena cava the way other arteries and veins do.

So what’s a heart attack?A heart attack happens

when your coronary arteries become blocked. This causes the cells to die and leave your heart damaged. Too much damage will cause your heart to beat out of rhythm and possibly fail.

(The same basic premise happens in a stroke.)

If caught early enough, a bypass can be performed to restore blood flow to the heart.

BloodBlood is important to

your body because it contains red blood cells (hemoglobin), white blood cells (immunity), platelets and plasma.

Plasma is the clear fluid that they all travel in. It is mostly made of water and also carries your nutrients.

Blood

Red blood cellsRed blood cells

contain hemoglobin, a protein that contains iron and combines with oxygen.

Too little iron in your blood and you will be weak due to the lack of oxygen to your cells (anemia).

White Blood CellsWhite blood cells work

with your immune system to keep you healthy.

These cells aren’t really white; they’re clear. We just call them white because they look that way on a microscope slide. Most of the time, we dye them colors so that we can see them.

The path of a red blood cell

Left atrium

Left ventricle

Right atrium

Right ventricle

Deoxygenated blood Body

Lungs

Blood

arteries and capillaries

capillaries and veins

Red blood cells deliver oxygen and other nutrients to the entire body. They pick up wastes like carbon dioxide.

Red blood cells receive oxygen from the lungs and let off carbon dioxide

Bicuspid valve

Vena Cava

Tricuspid valve

Aorta

Pulmonary veins

Oxygenated bloodPulmonary

arteriesPulmonary valve

Getting OxygenYour body gets

oxygen using your respiratory system.

Your respiratory system is made of several organs.

The smallest of these organs is the alveoli in your lung.

Upper Region of Respiratory System

Mouth/Nose: both take in air, but the nose helps to warm and moisten it.

Pharynx is the portion where the two meet.

Epiglottis protects your trachea from your food.

Larynx (voice box) produces speech.

Lower Respiratory SystemLungs: Bring air in

through the bronchi to the alveoli

Alveoli are surrounded by capillaries

The capillaries drop off carbon dioxide and pick up oxygen. Both of these happen through diffusion.

Diaphragm: The muscle that controls your breathing.

BreathingBreathing in and out is

made possible by a muscle called the diaphragm.

When the diaphragm moves down, it sucks air into you lungs (inspiration/inhalation).

When the diaphragm moves up, it pushes air out of your lungs (expiration/exhalation).

How does that work?Check here to see what happens when you

breathe:

DiaphragmThis is how the alveoli work:

Breathing

The Diaphragm and the Alveoli

The respiratory system is one system that excretes (gets rid of) wastes. We call it a waste system because it gets rid of carbon dioxide, a waste product.

Another system that gets rid of wastes is the Excretory (urinary) system.

This system takes wastes from your blood and sends it out through urine.

Systems that excrete waste

Urinary (Excretory) systemYour urinary system is

very simple and only contains 4 organs:2 kidneys2 ureters1 bladder1 urethra

Your kidney collects waste from your blood and gets rid of it in your urine. The main working part of your urinary system is called the nephron and is found in the kidney.

NephronThe inside of your kidney

looks like this:

The nephron is a small part of the kidney surrounded by capillaries that drop off wastes and excess water through diffusion and osmosis. It all collects in the center of the kidney and goes to the bladder through the ureters.

Urinary BladderThe urinary bladder is like a

giant balloon that is controlled by you and your brain.

As urine filters in, the bladder puffs up. This sends a signal that the bladder is getting full.

When it’s full, your brain will open the internal sphincter when it’s time to urinate and you hold the external sphincter closed until you can get to a bathroom. (Maybe.)

So why do girls get bladder infections and boys don’t?Check out the

differences in the anatomy of boys and girls.

Yes we know that boys have a penis and girls have a vagina, but notice the difference between the urethra in each gender.

Having a shorter urethra could allow bacteria to enter into the bladder causing an infection. (Remember front to back ladies!!!)

Front view

Side view

What is kidney failure?Kidney failure is when

your nephrons can no longer filter enough wastes from your blood to keep you healthy.

Without this filter, you will become sick and eventually die.

Patients in kidney failure receive dialysis treatment several times a week.

Dialysis video

Integumentary SystemSkin is another excretory system because it gets rid of wastes in many different forms. It makes up the largest organ in your body and covers the outside and inside of your body.

The main job of your skin is to help maintain your body temperature.

EpidermisThe top layer of skin is called the epidermis.The lowest part of

the epidermis makes melanin.

As the skin moves upward, it dies and is converted into keratin, which makes your skin waterproof.

DermisThe dermis is found underneath the epidermis. All of the important tissues are found here.The sweat gland produces

sweat (a waste product) to cool you off.

Skin also produces oil to keep your skin soft. These glands sometimes get blocked by bacteria and form a pimple.

Blood vessels here are why you bleed when you get a paper cut.

Skin also contains capillaries that exchange food, oxygen and wastes.

Hair and nailsThe basic structure of hair and nails is keratin.

• Hair insulates from the cold and protects your eyes, nose, and ear from things that enter. Skin also contains muscles that pull your hair and make it stand up when you are cold or scared.

• Nails come from the nail root. Nails fill with keratin a tough substance that covers and protects the tips of your finger and toes.

Skin cancer Skin cancer is an

abnormal growth of cells in your skin.

Repeated exposure to sunlight creates mutations in the DNA. Sometimes, the controls for mitosis become mutated and the cells begin to divide uncontrollably.

Vitiligo

Skin tags

Neurofibromatosis

Sunburn Skin allergy

Mole

All of the systems discussed before use muscles.

The muscular system works in all of your body systems to help things move, breakdown, release something, etc.

The muscular system works with the skeletal system to move your body.

Muscular/Skeletal Systems

Types of MuscleThere are three main

kinds of muscle tissue:SmoothStriated (striped)Cardiac

Striated muscle is voluntary muscle. You can move it when you’re ready (skeletal muscle).

Smooth and cardiac muscle are involuntary and under the control of your brain.

Striated muscles are found attached to your skeleton. When you decide to pick up your pen, your muscles move your bones to go and get it. So these move at your control.

Smooth muscles are found in digestive organs and any organ under involuntary control, like your urinary bladder. Remember that these are controlled by your brain, not you. So smooth muscles work the things you don’t have to think about.

Cardiac muscle is found in your heart. Cardiac muscle beats in a rhythm and keeps your heart going.

Examples of Muscle Tissue

How do muscles work?Muscles can only contract,

they cannot lengthen or return to normal by themselves.

A contraction is the shortening of the muscle and happens in a portion of the muscle called a sarcomere.

Each sarcomere has two filaments called actin and myosin that attach and pull to contract or shorten the muscle.

What makes your muscles move your bones?

Remember that smooth and cardiac muscles are involuntary while your skeletal (striated) muscle is voluntary. So, you can control your skeletal muscles.

You have trained your biceps muscle to contract when you want to bend your arm and your triceps muscle to contract when you want to straighten your arm.

How do muscles move bones?Muscles are

attached to bones by tendons.

When the muscles contract, they pull the bone they are attached to toward it.

How do muscles do that?Muscles work in pairs.For example:

To bend your arm at the elbow, you contract or shorten your biceps muscle, pulling your hand up.

To straighten your arm at the elbow, your triceps muscle contracts, pulling your forearm down.

Skeletal systemBones serve three

basic purposes:To protect your

internal organs.To keep your body

upright. To make blood cells.

Bones work with muscles to move you around.

What’ s in a bone?Bone contains several

different things:Epiphyseal plate-

growth plateYellow marrow-fat

cells (the stuff that your dog goes after)

Red Marrow (bone marrow)-where blood cells are madeSo bones are actually

responsible for making your blood!

How do bones move?Remember that

muscles are attached to bones by tendons. When a muscle moves, it pulls the tendon which then pulls the bone it’s attached to.

Bones are attached to other bones by ligaments.

What else is in bones?Bones also include

blood vessels and nerves. This allows all of the bone cells to get food and water. It is also why you feel it when you hurt a bone.

How are bones connected?Bones stay together

because of two main things:They are attached to

muscles by tendons.They are attached to

other bones by ligaments.

If you’re Jay Cutler, you don’t like ligaments!

So what’s cartilage then? You already know

cartilage because of your ear and nose. Cartilage is a tough connective tissue that your body uses for many different reasons. For bones, cartilage is found between bones to help them slide across one another as they move.

Nervous systemThe nervous system helps

coordinate the body’s response to changes in its internal environment. This means that in interprets and helps your body react to any situation.

The nervous system includes the nerves in your body, your spinal cord and your brain, which are all made of nerve cells.

NervesNerve cells work by

sending electrical signals from one nerve cell to another until the signal reaches your brain or another part of your body.

Nerve cells are also called neurons.

BrainYour brain’s job is to

interpret the signals that it receives from the different parts of your body.

Your brain responds to the signals and usually causes some kind of reaction.

Notice that different parts of your brain control different things.

Major parts of the brainYour brain is made of

several different parts:Cerebrum: the largest

part of the brain. It controls your general thought processes and memories.

Cerebellum: It controls movement and coordination

Brainstem: It has three different parts that serve as relays between your body and brain. They help regulate automatic processes like breathing.

Spinal CordThe spinal cord

attaches to your brain through the brain stem.

All of the nerves in your body send messages to your spinal cord and the spinal cord sends it up to the brain. This is why you become paralyzed if the cord is damaged.

MeningesYour spinal cord and

brain are protected by several layers of tissue called the meninges and by fluid called cerebrospinal fluid.

These help to get blood to and from your brain and provide a cushion from everyday bumps and bruises.

NeuronNeurons are nerve

cells. They relay information.

Each neuron has three parts: Dendrites that pick

up the signal Cell body that

contains the nucleus and other organelles

Axon that sends the signal to another cell

Action Potential (Impulses)Information is sent

through electrical impulses

These impulses use chemicals in your body (Na+ and K+) to send the signals down the length of the axon to another neuron

When the impulse reaches the synapse, a neurotransmitter is released to start the impulse in the next neuron.

Check out these videos on how it works:

The Nerve Impulse

Nerve Impulse Animation

Types of NeuronsThere are three

kinds or neurons that we are interested in:Sensory neuronsMotor neuronsInterneurons

Each does a specific job in your nervous system.

Sensory/Motor NervesSensory

neurons are found in skin and organs. They pick up the signal and send it to the brain.

Motor neurons bring signals from the brain and tell muscles to move.

Immune systemYour immune system

is designed to protect your body from disease causing agents. These things are known as pathogens.

Your immune system includes bones (white blood cells), lymph nodes, thymus gland, tonsils and spleen.

So what is immunity?Immunity is the

process by which your body makes cells that fight infection (pathogens).

A disease is any change other than injury that disrupts normal body functions.

A disease can be spread by infected animals, contaminated food, or physical contact.

Nonspecific Defenses: First Line of Defense

Your body can fight pathogens as a group or individually. Nonspecific defenses fight all threats to your body as if it was a group. These are ways that your body tries to keep all pathogens out or kill them before you get sick.

Nonspecific Defenses: Second Line of Defense

Your integumentary system is your first line of defense.

If something gets past your skin, your body produces an inflammatory response. The response uses white blood cells and swelling to fight the invader.

A fever usually tells you that your body is fighting something. A fever helps to slow the growth of a particular pathogen.

Specific DefensesPathogens that make it

past nonspecific defenses now face your body’s specific defenses.

An immune response is the response to a specific pathogen that has invaded your body. The response is triggered by an antigen on the membrane of the pathogen. This includes production of white blood cells called B cells and T cells made in the spleen.

What happens if the pathogens become too great for your body to handle?

There are two ways to help your body out if there are too many pathogens for your system to handle: antibiotics and antivirals.

Antibiotics are used when a bacterial growth (infection) becomes too large for your body to fix on its own.

Antibiotics help to kill some of the bacteria so that your body can take control again.

Antivirals are still pretty new to the market, but seem to work well.

Antivirals stop the flu virus from reproducing or spreading to new cells. In this way, your body can kill the infected cells and help you to feel better faster.

What happens if the pathogens become too great for your body to handle?

VaccinesA vaccine is an attempt at

acquired immunity (introducing the virus without getting you sick).

A vaccine is a prepared solution of weakened or killed pathogens.

By taking a vaccine, you are exposing your body to a pathogen hoping that you will create a specific defense against it. This way, your body will be able to fight it off if you get it.

CancerCancer is actually a

mistake in mitosis. Cells usually stop growing when they touch another cell, but cancer cells do not.

As they grow, they can steal nutrition from healthy cells and outgrow them to create a mass called a tumor.

Some tumors are okay (benign); some are dangerous and spread (malignant).

Endocrine SystemThis system is made

up of many glands that produce chemicals. These chemicals control other parts of the body.

Types of HormonesHormones made of

amino acids (proteins) are produced in the hypothalamus, pituitary gland, pancreas, parathyroid and thyroid glands, and the adrenal medulla.

Hormones made of steroids are found in the adrenal cortex, ovaries and testes.

Hypothalamus and PituitaryThe hypothalamus

controls the pituitary gland. It also helps to control contractions during childbirth.

The pituitary gland controls the other endocrine organs and makes growth hormone.

Thyroid and ParathyroidThe thyroid gland

controls the parathyroid gland and makes calcitonin which controls how much calcium is absorbed by your body and used in your bones.

PancreasYour pancreas produces

many hormones that aid in digestion.

The most known are insulin and glucagon. Insulin stimulates your body to store sugar, keeping your blood sugar count low. Glucagon stimulates your body to release sugar when you need it.

Adrenal glandsThe adrenal cortex

makes cortisol (for carb and protein metabolism) and sex hormones.

The adrenal medulla makes epinephrine and norepinephrine which work in response to fear, hurt, pain, etc.

Ovaries and testesOvaries control the

secondary sex characteristics in a female (larger breasts, wider hips) in preparation for childbirth. Ovaries also produce gametes (eggs).

Testes control the secondary characteristics in a male (deeper voice, more hair/muscle) in preparation for finding a mate. Testes also produce gametes (sperm).

HomeostasisHomeostasis in your body is controlled

by your nervous system and endocrine system. The brain contains control with input from the hypothalamus and the pituitary gland.

Homeostasis is controlled through a feedback system. This means that your brain looks for chemical signals from your body and then acts on them.

Negative FeedbackNegative

feedback stops the production of a protein or hormone based on its levels in the blood.

Positive Feedback

Positive Feedback is almost the opposite.Instead of stopping an action or a response,

this type of feedback continues the change or stimulus until a certain point is reached.

The reproductive system of males and females are similar. (No that does not mean that everyone is a he-she.)

Each gender has an organ that creates gametes (testes for boys; ovaries for girls).

The cells in those organs go through meiosis to create sperm and eggs that will combine to make children.

Speaking of babies……..

Boys first!I know that you really

don’t want to see this picture but too bad!

Sperm is made in the testes, but stored in the epididymis.

Sperm will travel through the vas deferens until it meets the urethra.

The prostate and seminal vesicles add materials to the sperm and together they make semen.

Girls next!We already know

that the eggs are made in the ovaries. Each month, one of the ovaries releases an egg in hopes of becoming fertilized.

If the egg is fertilized, the fetus grows in the uterus and leaves the mother through the vagina.

PregnancyMany changes take place

during pregnancy; most of which are not good for a woman’s body.

Notice that all of the regular organs are pushed out of the way to make room for the baby to grow.

Mom’s body becomes totally focused on giving you everything that you need to live.

PregnancyThis is the amniotic sac.You grow in this sac

until you are ready to be born.

Unlike popular stories, you do not breathe in the water here.

But, sometimes you swallow it and give your digestive system a chance to work and your kidneys a chance to filter your blood.

BirthYou are born as your

body comes through the birth canal (vagina).

The umbilical cord that attached you to mom is cut ending that bond forever. Now you get to live life on your own.

Labor Labor consists of a

series of contractions that get the female body ready to push the baby out.

Labor has 3 different stages. Each one creates a change in the cervix that helps it to open and allow the baby to pass through.

Watch this video to see a review of the stages.

Labor and Birth

Birth processWhile most women choose

to have a natural childbirth, that is not always possible for many different reasons.

Natural childbirth is birth without the use of pain relieving drugs. A Cesarean section (C-section) is the opposite of natural childbirth, using lots of doctor intervention.

Look at these videos to see the difference between them.

Natural childbirth

C-section