The Circulatory System

YO!Been a long

time!

#4 Circulatory System OverviewThe circulatory system is the network of heart and vessels moving blood through the body

The mileage of vessels you have in your body is ridiculous. Laid end-to-end, your blood vessels would easilycircle the Earth.

Whoa.

#5 FUNCTIONS of the Circulatory System

Remember, when you see the word “function,” just think: JOB.

1. Carries nutrients to cells from digested food

2. Carries oxygen to cells from inhaled air

3. Carries wastes from cells to kidneys & lungs.

4. Fights diseases

So it looks like there’s a lot of“carrying” going on. Think of the circulatory system being likethe highways & roads…they letimportant stuff get from here tothere inside your body.

#6 STRUCTURE No.1—The HeartYou normally don’t notice your heart at work. Only after you’ve runa mile or seen your crush walk past you down the hallway do youseem to notice it at all. But it’s always at work, constantly pumpingblood through your vessels.

First, let’s clear up some misconceptions…(Joe needssome thickness)

The heart doesn’t look like aValentine:

It’s also not to the far left of your chest... it’s actually closer to the middle of your chest. Because it’s slightly tilted and strongest on the left, it tricks us where it’s location truly is.

#7 Heart, continuedThe heart is made of cardiac muscle, and has 4 chambers.

Well, this is tricky to draw…Instead, draw a normal heartshape, divide it into fourths,and letter them as such:

a

b

c

d

#8 Heart, continueda

b

c

d

Let’s see what these different chambers are & do.

a. left atrium – receives high O2 blood from lungsb. left ventricle – pumps high O2 blood to bodyc. right atrium – receives low O2 blood from bodyd. right ventricle – pumps low O2 blood to lungs

If you trace through what is goingon here, you’ll see that the heartreceives & pumps blood through two loops…one loop sends bloodto the lungs to freshen up with oxygen, the other loop sends bloodto the body so cells can grab at thatoxygen. TWO LOOPS!

PulmonaryCirculation

SystemicCirculation

#9 STRUCTURE No.2—Blood Vessels

If we compare your circulatory system to a system of highways & roads, then I’m not quite sure what the heart would be.

But I DO know what the blood vessels are…they’re the actual freeways,side streets, and back alleys where all the action in your body occurs.

#10 Blood Vessels, contd.Texas is about 800 miles up and down, and about the same distanceacross.

But in that space, over79,000 miles of highways are laid out. That doesn’teven count the smallerroads.

Likewise, despite being around 5 or 6 feet tall, your body has between70 to 100 THOUSAND miles of blood vessels. That’s worth 3 or 4 trips around Earth.

#11 Blood Vessels, contd.

Blood vessels are lined with smooth muscles. This gives themthe ability to change thickness. Some are more capable of thisthan others.

#12 Blood Vessels, contd.For the most part, each red vessel you see is an artery – carries blood away from the heart.

Each blue vessel here is a vein – carries blood back to the heart.

Most diagrams like this show redas being high O2 blood. Arteriesnormally carry this to the rest of thebody.

Blue usually represents blood low in O2. Veins take this blood backto the heart so that it can be sent to the lungs to recharge.

#13 Blood Vessels, contd.Think about what happens on big highways. Traffic is moving so fast,that a postal worker in her van wouldn’t have a chance of driving by a mailbox and getting anything in or out of it.

The arteries and veins are like that…way too big,and way too much blood moving way too fast for any cells to get the stuff they need out of the blood.

Where does a postal worker do her work? Onsmall side streets, where traffic is very slow andvery orderly. That’s where trash pickup happens, too.

These so-important side roads and neighborhood streets are the capillaries ofyour body.

#14 Blood Vessels, contd.Capillary – tiny vessel that connects arteries to veins. Gases, nutrients,and wastes are exchanged with cells in these.

You can think of the capillaries asplaces where the blood exits onehighway, conducts its business,then makes a U-turn back to whereit started from down a differenthighway.

#15 STRUCTURE No.3—BloodWhat is blood, anyway? You might be surprised to find out what itsmade of. It looks like a smooth, red liquid, but looks can be deceiving.Blood is actually made of different cells & tissues.

About half of the bloodis plasma, the yellowish clear liquid part of blood.It’s mostly water.LOTS of chemicals ride this liquid waterway in the body.

#16 Blood, contdYour body has trillions of red bloodcells. These disk-shaped cells are sopacked together that they make the blood appear red, instead of showingup as little polka-dots in the yellowfluid.

Red blood cells carry oxygen to theother body cells, using a special ironcompound to hold onto the oxygen.

Red blood cells are made by the millions per day in the middle of yourbones!

Left: an abnormal sickle-cellRight: healthy RBC

#17 Blood, contdWhite blood cells are solitary warriors. They’re way outnumbered by yourRBCs, otherwise your blood mightbe more pink than red.

WBCs fight germs and eat dead bodycells. Useful stuff, eh?

A WBC battles a force oftiny bacteria.

#18 Blood, contdAnd when you get a cut, why don’tyou just bleed and bleed and bleed todeath? Thank your platelets.

Platelets are blood cells that clumptogether with special chemicals at acut to make a clot.

Platelets havewebbed totrap theseRBCs fromescaping.

#19 DISORDERS & PROBLEMS

It’s great when your circulatory system is healthy & runs flawlessly.But there are dozens of problems that can arise when it becomes worndown or dysfunctional due to disease & abuse. Where’s Joe?

Uhh…???

#20 Disorders, contd.Let’s say that Joe eats a bad diet. Lots of greasy food, fried everything.On top of that, he sits around all day and never really does anythingactive. You can imagine…

This isn’tactive? My thumbs hurt!

#21 Disorders, contd.Joe is heading toward a condition known as atherosclerosis. The combination of high-cholesterol, fatty foods entering his blood and little exercise, the fat clogs up the insides of his arteries. Check it out…

Barely any room for blood to get through, huh.On top of the cramped space in there, the cholesterol will damage & scar the artery, causingit to harden to where it doesn’t bend easily.

AVOID THIS CONDITION BY EATING LOW-FAT FOODS, STAYING HYDRATED, AND EXERCISING.

#22 Disorders, contd.What would be easier for your heart to pump a teaspoon of waterthrough…a tiny little straw or a nice, wide pipe?

But since Joe has been lazy and unhealthy, his once-wide arteries are narrowed with blockage to the size of straws. This condition, calledhypertension, is known as “high blood pressure.” It basically means the heart works way too hard to pump blood through vessels.

There are other causes of hypertension, but many are avoidable. AVOID THIS CONDITION BY EXERCISING, CHECKING YOURBLOOD PRESSURE, AND AVOIDING EXCESSIVE SALT.

#23 Disorders, contd.Joe’s feeling a little numb in his arm, yet his fingers are tingling. Ashooting pain rockets past his elbow. Now his chest feels tight…reallytight.

Joe is likely experiencing the beginning stages of a cardiacarrest. Better known as a heart attack, it happens when one ofthe small arteries feeding oxygen & nutrients to the heart becomes blocked…the heart muscle falls asleep and coulddie. Joe’s life is in serious danger.

AVOID THIS CONDITION BY, WELL, ESTABLISHING HEALTHY EATING &EXERCISING HABITS NOW, WHILE YOU ARE YOUNG.

#24 Will Joe Make It?Let’s spare Joe’s life this time.

Whew!Back to the X-Box!

And while some people never learn, hopefullyyou have.

Let’s review the Circulatory System real quick.

#25 ReviewIf your Circulatory System suddenly disappeared, would you survive?To see, let’s check the functions of the circulatory system and seethe result of those things not happening any more.

1. Carries nutrients to cells from digested food

Joe would starve to death in a couple/few weeks

2. Carries oxygen to cells from inhaled air

Joe would suffocate to death in a few minutes

3. Carries wastes from cells to kidneys & lungs.

Joe would poison himself to death in a few days, probably

4. Fights diseasesThis would be gruesome. You might be able to literally watchJoe get “eaten” alive by bacteria and other microbes in amatter of several hours. YOU CAN’T LIVE WITHOUT IT!

#26 ReviewHomeostasis – how does the circulatory system help keep things in balance?•Getting rid of wastes that would poison you•Keeping the level of germs in your body at a manageable level•Keeping cells far from your guts and lungs supplied with oxygen &nutrients

Stimulus : Response(something you respond to) : (how you respond)Tired muscles while exercising : much faster heart rate to feed O2

#27 And That’s…

WAIT! One thing…a lot of people ask about the color of blood.Your blood is red, but the shade of red depends on the oxygencontent. High-oxygen blood is a brighter red. Low-oxygen blood,like in your veins, looks darker (almost purplish).

But it’s never “blue.” Blood is just 2 shades of red.