Ms. Franz

.4 AP Biology- MHS

March 3, 2008

Arteries Blood vessels that carry blood away from the

heart. Carry oxygenated blood Tough on the outside and smooth on the

inside Have 3 layers: outer tissue layer, a muscular

middle and an inner layer of epithelial cells

Arteries The muscle in the middle is elastic and very

strong Helps the heart pump the blood When the heart beats, the artery expands and

fills with blood When it relaxes, the artery contracts and

pushes the blood along

Arterioles Branch from the arteries Receive blood from the arteries They are smaller than the arteries They are strong and relatively thick Carry blood away from the heart to the tissues

of the body Important in blood pressure (BP) regulation

Capillaries Branch from the arterioles Very thin and fragile Involved in the body’s release of excess heat During exercise, your body and blood temperatures

rise. To release this excess heat, the blood delivers the heat to the capillaries which rapidly release it to the tissue

Your skin turns a flushed, red appearance Ex) Hold your hand under hot water and it will

quickly turn red for the same reason

Capillaries cont. Blood can only pass through in a single file The exchange of O2 and CO2 takes place

through the capillary wall RBC release the O2, it passes through the

wall and into surrounding tissue The capillaries then pass their waste-rich

blood to the veins for transport back to the heart

Venules Vessels that collect blood from capillaries Carry blood that’s low in oxygen content Join together to form veins Spider veins- caused by

dilated venules

venule dilation is due to

valve damage

Veins Vessels that transport blood to the heart Lie close to the surface Thinner-walls and thus transport blood at a

lower pressure More easily damaged Have 3 layers: an outer tissue layer, a muscle

in the middle and a smooth inner layer of epithelial cells

Veins cont. Receive blood from the capillaries after the

exchange of O2 and CO2 has taken place Transport waste-rich blood back to the lungs

and heart Important this waste-rich blood continues

moving in the right direction and not backwards This is accomplished by valves inside the veins Valves are like gates

Veins cont. Vein valves are necessary to keep blood

flowing toward the heart and allow blood to flow against the force of gravity

Ex) blood flowing from the foot has to be able to flow up the leg and to the heart

Vein valves provide footholds for the blood as it climbs it way up

How is it that we can see our veins?

the waste-rich blood is the deoxygenated form of hemoglobin and makes the blood in veins appear dark a deep red color

Vein walls are thin and waste-rich blood can be seen through some body parts

LOOK at your wrist, ankles, hands inside elbow You can probably see your veins carrying blood

back to your heart *Your skin refracts light making the deep red look

a little blue

Functions of the Circulatory System It is an amazing highway that travels through your

entire body connecting all your body cells. Transports materials such as nutrients, water, and

oxygen to your billions of body cells throughout your body For example, glucose, a simple sugar used to produce ATP

Transport hormones - Numerous hormones that help maintain constant internal conditions

Carries away wastes from cells such as carbon dioxide

Functions cont. Contains cells that fight infection Helps stabilize the pH and ionic concentration

of the body fluids. It helps maintain body temperature by

transporting heat. The Veins and Arteries of the circulatory

system function to serve different areas in the body and supply them with the circulation they need to work properly and efficiently

A “Superhighway” The circulatory system consists of a lot of one

way streets. The superhighways of the circulatory system

are the veins and arteries

Let’s take a look at each of these one way streets that together form the superhighway of our circulatory system

Systemic CirculationIt’s all throughout the body

It’s a major part of the overall circulatory system. Supplies nourishment to most of the tissue

throughout your body, (except the heart and lungs they have their own systems)

The blood vessels (arteries, veins, and capillaries) deliver oxygen and nutrients to the tissue.

The aorta carries and distributes oxygen rich blood to all arteries.

Most major arteries branch off from the aorta

During systemic circulation, blood passes through the kidneys renal circulation

The kidneys filter much of the waste from the blood. Blood also passes through the small intestine

portal circulation The blood from the small intestine collects in the

portal vein which passes through the liver. The liver filters sugars from the blood, storing them

for later.

Superior vena cava- receives blood from the head, neck, chest, shoulders and arms

Inferior vena cava- collects most of the venous blood from organs below the diaphragm

Hepatic portal vein- collects blood from visceral organs in the abdominopelvic cavity Delivers blood to capillary networks in the liver

Aorta The hearts main artery Leaves the heart and heads toward the head via the

*aortic arch* The arch turns into the *descending aorta* which

goes behind the heart and down the center of the body distributing blood (aka-thoracic, abdominal)

inside layer is very smooth, allowing the blood to flow quickly

outside layer is very strong, allowing the blood to flow forcefully

Try this at home! Lie down on your back Look down at your abdomen Sometimes when you look at your abdomen

pulsates with each heart beat DON”T WORRY! This is normal This pulsation is the aorta throbbing with each

heart beat

Pulmonary Circulation

movement of blood from the heart, to the lungs, and back to the heart again

The heart is divided into 4 chambers, 2 associated with each circuit: R. Atrium- receives blood from the systemic body circuit R. Ventricle- discharges it into the pulmonary (lungs) circuit L. Atrium- collects blood from the pulmonary circuit L. Ventricle- ejects blood to the systemic circuit

When the heart beats, the two ventricles contract at the same time, ejecting equal volumes of blood

The two atria are separated by the interatrial septum (WALL) The two ventricles are divided by the interventricular septum

(WALL)

Blood Flow Through the Heart The veins bring waste-rich blood back to the heart Blood travels from the right atrium into the right ventricle

through a broad opening called the Tricuspid valve Papillary muscles on the inner surface and anchor the valves

to the heart (tricuspid and mitral valves) The right ventricle fills and then contracts, pushing the blood

into the pulmonary trunk, which is guarded by the semilunar valve

From the trunk, blood flows in to the left and right pulmonary arteries

These arteries branch repeatedly with in the lungs

This supplies the capillaries, where the exchange of carbon dioxide and oxygen takes place

Blood collects into the left and right pulmonary veins These veins return and empty into the left atrium Like the right atrium, there is a valve bicuspid or mitral

valve Blood flows from the left atrium, through the mitral

valve and into the L. ventricle Blood leaves the L. ventricle passing through the aortic

semilunar valve and into the body via the ascending aorta

Pulmonary Circulation cont. The one-way valves are important for preventing any

backward flow of blood The circulatory system is a network of one-way

streets. If blood started flowing the wrong way, the blood gases (oxygen and carbon dioxide) might mix, causing a serious threat to your body

You can use a stethoscope to hear pulmonary circulation

The two sounds you hear, "lub" and "dub," are the ventricles contracting and the valves closing.

Pulmonary Circulation cont. The SA node (sinoatrial or sinus node) is the heart's

natural pacemaker consists of a cluster of cells that are situated in the

upper part of the wall of the right atrium (right upper chamber)

electrical impulses are generated there If these impulses cannot be created on their own, an

artificial pacemaker for the heart can be inserted The electrical signal moves from cell to cell down

through the heart until it reaches the AV node

Pulmonary Circulation cont. Atrioventricular node (AV): is an electrical relay

station between the atria (the upper) and the ventricles (the lower chambers of the heart).

Serves as a gate to slow electrical currents Electrical signals from the atria must pass through

the AV node to reach the ventricles. controls heart rate generates electrical impulses and conducts them

throughout the muscle of the heart, stimulating the heart to contract and pump blood.

Component of the Blood What makes up our blood? Red Blood Cells (RBC) White Blood Cells (WBC) Platelets Plasma RBC, WBC and Platelets are made by bone

marrow (a soft tissue inside our bones)

Red Blood Cells (erythrocytes) Carry O2 and CO2

Pick up O2 in the lungs and transport it to cells Gathers CO2 (waste from working cells) and

transports it to the lungs where it gets exhaled (breathe out)

There are about 5,000,000 RBC in ONE drop of blood

White Blood Cells (leukocytes) Help fight off germs by attacking and

destroying them as they enter the body When you have an infection, your body will

produce more WBC to help fight it If our WBC cells need a little help with a lg.

scale infection, the Doctor will prescribe an antibiotic to help

There are ~10,000 WBC in ONE drop of blood

Platelets (thrombocytes) Blood cells that help stop bleeding When we cut ourselves, we’ve broken a blood

vessel and blood leaks out Platelets start sticking to the opening of the

broken vessels to plug up the holes As platelets stick, they attract more platelets,

fibers and other blood cells When the bleeding stops scabs There are ~250,000 platelets in ONE drop of

blood

Plasma Liquid part of the blood ~ ½ of our blood is plasma Carries blood cells throughout the body Made in the liver ONE drop of blood contains a half a drop of

plasma

The Heart The heart is an amazing organ. It is the main component of the circulatory

system It beats about 3 Billion times during an avg.

lifetime It is a muscle about the size of your fist Located in center of your chest slightly to the

left

Heart Rate

Usually it is calculated as the number of contractions (heart beats) of the heart in one minute and expressed as "beats per minute" (bpm).

When resting, the average adult human heart beats at about 70 bpm (males) and 75 bpm (females)

The infant/neonatal rate of heartbeat is around 130-150 bpm, the toddler's about 100–130 bpm, the older child's about 90–110 bpm, and the adolescent's about 80–100 bpm.

The pulse is the most commonly used method of measuring the heart rate

Blood Pressure (BP) What Is Blood Pressure? BP is the force of the blood pushing against the

walls of the arteries. Each time the heart beats (about 60–70 times a

minute at rest), it pumps out blood into the arteries Your BP is at its highest when the heart beats,

pumping the blood systolic pressure When the heart is at rest, between beats, your blood

pressure falls diastolic pressure

BP Blood pressure is always given as these two

numbers, the systolic and diastolic pressures – both are important

The systolic pressure is the top number and the diastolic is the bottom, such as 120/80 mmHg (measured in millimeters of mercury)

If your blood pressure is 120/80, you say that it is "120 over 80."

BP Blood pressure changes during the day It’s lowest as you sleep and rises when you

get up It rises when you are excited, nervous, or

active For most waking hours, it should stay pretty

much the same when you’re standing or sitting still

High Blood Pressure If one or both numbers are usually high, you

have high BP A BP of 140/90mmHg is considered high BP Uncontrolled high BP is dangerous and can

lead to stroke, heart failure, heart attack, kidney failure or blindness

High BP is called the Silent Killer b/c there are usually no signs or symptoms

BP Table

CategorySystolic (top

number)Diastolic (bottom

number)

Normal Less than 120 Less than 80

Prehypertension 120–139 80–89

High bloodpressure

   

     Stage 1 140–159 90–99

     Stage 2 160 or higher 100 or higher

Coronary Artery Disease an obstruction of the coronary (heart) arteries Strenuous activity causes the heart to work

harder to supply oxygen-rich blood. The constrictions in coronary arteries prevent

the heart from receiving the necessary amount This insufficient supply of blood to the heart

muscle results in oxygen deprivation, a condition called myocardial (heart) ischemia.

Congestive Heart Failure (CHF) occurs when weak heart function is accompanied by

a build up of fluids in the body blood flow slows, decreasing the amount of blood

pumped from the heart. Blood returning to the heart backs up in the veins

and forces fluid into surrounding tissues (often the feet and legs) to swelledema

edema can spread to other parts of the body, including vital organs, such as the lungs, which can be life-threatening

~400,000 Americans are diagnosed with CHF each year

Heart Attack

myocardial infarction occurs when the blood supply (via coronary arteries) to

part of the heart muscle is severely reduced or stopped Usually caused by the buildup of plaque (deposits of fat-

like substances) The plaque can eventually burst, tear or rupture, creating

a "snag" where a blood clot forms and blocks the artery heart attack

If the blood supply is cut off for more than a few minutes, muscle cells suffer, they can be permanently injured and die

This can kill or disable someone, depending on how much heart muscle is damaged

Anemia a deficiency of red blood cells or the hemoglobin

molecules within them Oxygen has trouble getting where to it needs to hemoglobin is not accessible the blood struggles to bring oxygen molecules to

tissues for energy in the body can be very serious because the human body

depends on oxygen to survive. Symptoms: Weakness, fatigue

High Cholesterol What Is Cholesterol? Cholesterol is a waxy, fat-like substance that is

found in all cells Your body needs some cholesterol to work the right

way and it makes all the cholesterol it needs on its own

Found in some of the foods you eat. Body uses cholesterol to make hormones, vitamin D,

and substances that help you digest foods.

High Cholesterol Blood is watery, and cholesterol is fatty, therefore,

just like oil and water, the two do not mixplaque Cholesterol is carried in small packages to the

bloodstream called lipoproteins The small packages are made of fat (lipid) on the

inside and proteins on the outside. Two kinds of lipoproteins carry cholesterol

throughout your body. It’s important to have healthy levels of both:

Lipoproteins Low-density (LDL) sometimes called bad

cholesterol High LDL cholesterol leads to a buildup of

cholesterol in arteries increases your chances of having heart disease

High-density (HDL) sometimes called good cholesterol

HDL carries cholesterol from other parts of your body back to your liver, where it is removed from the body

The higher your HDL cholesterol level, the lower your chance of getting heart disease.