Circulatory System

Standards: SAP 1 – Students will analyze anatomical structures in relationship to their physiological functions. SAP 4 – Students will analyze the physical, chemical, and biological properties of process systems as these relate to transportation, absorption, and excretion, including the cardiovascular, respiratory, digestive, excretory, and immune systems.

Functions of the Circulatory System: 1. Transports nutrients from intestines to all cells of the body some cells require more nutrients than others (ex. brain cells,liver cells, active muscle cells)

2. Transports nitrogenous wastes from cells of the body to the kidneys your cells produce nitrogenous wastes when they break down proteins

3. Transports oxygen from your lungs to cells of the body cells need O 2 to produce ATP (energy) This process is called aerobic respiration

4. Transport carbon dioxide from your cells to the lungs to be exhaled CO 2 is a by product of aerobic respiration

5. Transports hormones from the endocrine gland that produce them to their target cells insulin is produced in your pancreas it is transported in your bloodstream to cells in muscles and liver

6. Distributes heat throughout the body if you are too hot, blood is brought to your skin so the heat can be removed as sweat evaporates

if you are too cold, blood flow to the skin is restricted, allowing you to conserve heat in the body

Components of the circulatory system A. Blood vessels – function to transport blood throughout the body

5 major types of blood vessels 1. Arteries – vessels that transport blood away from the heart they usually carry oxygenated blood

2. Arterioles – small arteries important because the smooth muscle in their walls can constrict and relax constricting arterioles to one area of the body reduces blood flow to that area

example – when you are cold, you constrict the arterioles that send blood to your skin

3. Capillaries – the smallest of all blood vessels (some are slightly larger than a single red blood cell) capillaries are important because their walls are thin enough to allow the exchange of materials (O 2, CO 2, wastes, nutrients, and hormones)

you have several thousand miles of capillaries

4. Veins – vessels that return blood to the heart they usually carry deoxygenated blood the largest veins in the body are the inferior and superior vena cavae (~ 1.2 inches in diameter)

the vena cavae empty blood returning from the body into the heart veins differ in structure from arteries in that veins:

are often larger in diameter have thinner walls because blood pressure in the veins is much less than that in the arteries have one-way valves that prevent the back flow of blood (keeps blood moving toward the heart)

5. Venules – (= “little vein”) – tiny vessels that transport blood from the capillaries to the veins heart  arteries  arterioles  capillaries  venules  veins  back to the heart

Blood pressure varies as it flows through each type of vessel blood pressure is highest in the artery leaving the heart (aorta)

blood leaving the heart must be pumped under great pressure so that it can travel through the body

blood pressure falls steadily as it moves through the circulatory system It is lowest in the veins emptying into the heart (vena cavae)

B. Lymphatic vessels – function to collect fluid that leaks from the capillaries and return it to the circulatory system

about 3 liters of fluid leak from your capillaries each day this could be harmful to your health because you have only 5 – 6 liters of blood

capillaries leak because they are so thin (only 1 cell layer thick)

every time your heart beats, fluid is forced out of the capillaries and into the surrounding tissues this fluid enters lymphatic capillaries where it is now called lymph

lymph flows into larger and larger lymphatic vessels, in a 1- way direction toward the heart

lymph is cleaned by tiny structures called lymph nodes as it makes its way toward the heart

some lymph nodes are scattered along lymphatic vessels, while others are concentrated in specific areas (armpit, neck)

If you have an infection in your hand, lymph nodes in the armpit on that side of the body become painfully swollen (filled with dead bacteria that have been filtered out of lymph returning from the hand)

clean lymph is dumped into 2 large veins that enter the heart – returning this fluid to the circulatory system

C. Blood – is made up of liquid (plasma) and 3 kinds of solids 1. Plasma makes up 55% of the total blood volume

Plasma contains: a large amount of water metabolites (ex. glucose, vitamins, and hormones) nitrogenous wastes (ex. urea) salts and ions (ex. sodium ions, chloride ions, and bicarbonate ions)

proteins

2. Solids make up 45% of the total blood volume The 3 major solids found in blood are red blood cells, white blood cells, and platelets

Red blood cells (erythrocytes) are flattened disks that function to transport oxygen

they are able to transport oxygen because they are packed with hemoglobin – a protein that binds to O 2 in the lungs and releases it to the cells in the body

RBCs differ from all other cells in the body in what they lose their nucleus when they start transporting O 2 since they do not have a nucleus, they cannot reproduce themselves and die after about 4 months – they must continually be produced

RBCs are produced in red bone marrow

If more RBCs die than are produced, you suffer from a condition called anemia individuals with anemia feel tired all the time because their cells are not getting enough O 2

White blood cells (leukocytes) are larger than RBCs and contain a nucleus

they function to defend your body against disease by attacking and destroying bacteria, viruses, and cancer cells like RBCs, WBCs are produced in red bone marrow

sometimes cancer occurs among pre-WBCs in the bone marrow – called leukemia

Platelets are fragments that function in blood clotting

platelets circulating in your blood vessels are inactive – activated when blood vessel is damaged once activated they release a clotting protein that triggers a series of reactions involving about 14 other clotting proteins

If all clotting factors are present in the blood, a fibrin net will be formed this net traps other platelets, RBCs and WBCs, forming a clot this clot plugs the damaged blood vessel, stopping bleeding

If you are missing only 1 of the clotting factors your blood will not clot and you will be suffering from a condition called hemophilia (free-bleeders disease)

Blood Typing: The surface of each RBC in you body displays about 100 different antigens the most important antigens on the surface of your RBCs are: A, B, and Rh

the presence of the A and B antigens determine your ABO blood grouping, while the presence of the Rh antigen determines whether you are positive or negative

1. ABO blood groupings in humans: A,B,AB, orO individuals whose RBCs are covered with A antigens (but no B antigens) have type A blood If you have type A blood, you have B antibodies (anti-B) floating in your plasma

individuals whose RBCs are covered with B antigens (but no A antigens) have type B blood If you have type B blood, you have A antibodies (anti-A) floating in your plasma

individuals whose RBCs are covered with both A and B antigens have type AB blood If you have type AB blood, you have neither A or B antibodies in your plasma

Knowing a person’s ABO blood type is very important in performing a blood transfusion If you are given an incompatible blood type, you will have a severe reaction in which the antibodies in your plasma attack the antigens on the surface of the RBCs entering your bloodstream, causing the RBCs to agglutinate (clump) and rupture

this type of reaction in called hemolysis the ruptured RBCs release hemoglobin, which may cause kidney damage

2. Rh system this system is so named because it was first worked out in the blood of the Rhesus monkey like the ABO grouping, the Rh system is based on antigens on the surface of your RBCs

people whose RBCs have Rh antigens are Rh positive people whose RBCs do not have Rh antigens are Rh negative

There are 8 possible blood types with the ABO and Rh antigens: A+,A+, A-,A-,B+,B+,B-,B-,AB +,AB -,O+,O+,O-O-

The most common problem with Rh incompatibility may arise during pregnancy

normally, there is no mixing of the mother’s and baby’s blood during pregnancy

however, during the birthing process, some of the baby’s blood mixes with it’s mother’s blood – if the mother is Rh- and her child is Rh+ she will begin producing Rh antibodies

fortunately this does not have an effect on the present pregnancy – however, if the mother were to ever become pregnant with another Rh + baby, her Rh antibodies (produced at the end of the 1 st pregnancy) would pass through the placenta and destroy the baby’s RBCs

Rh incompatibility is not much of a problem presently because if an Rh - woman ever gives birth to an Rh + child, she is immediately given a shot of Rho-GAM, which stops her body from producing Rh antibodies

she must receive a shot of Rho-GAM every time she becomes pregnant with an Rh+ baby

Blood Groups in the U.S. OABABRh + Whites 45%41%10%4%85% Blacks 48%27%21%4%88% Hawaiians 37%61%1.5%0.5%100%

Blood Types in Southeast U.S. A + = 1 out of 3A - = 1 out of 16 B + = 1 out of 12B - = 1 out of 67 O + = 1 out of 3O - = 1 out of 15 AB + = 1 out of 29AB - = 1 out of 167

Disorders of the Blood 1. Anemia – RBC production slows down (many different types)

2. Sickle cell anemia – inherited condition in which abnormal hemoglobin is produced, causing their RBCs to become deformed

these deformed cells cannot move through blood vessels as easily as normal RBCs these blood clots may cut off the blood supply to an organ

3. Mononucleosis – a contagious disease caused by a virus that infects the white blood cells

symptoms include fatigue, headache, dizziness, sore throat, and fever there is no cure, but with rest, the individual usually suffers no permanent ill effects

4. Leukemia – cancer of the WBCs normalleukemia

5. Hemorrhage – bleeding, either internal or external