Blood

Circulatory System

The circulatory system consists of: Heart

Blood Vessels

Blood

Adults have 4-6 liters of blood.

The study of blood is hematology

What are the Functions of Blood?

Transportation: Oxygen, nutrients, wastes, carbon

dioxide, and hormones

Defense: Against invasion by pathogens

Regulatory functions: Body temperature, water-salt balance,

and body pH

Composition of blood

Formed elements: produced in red bone marrow Red blood cells/erythrocytes (RBC) White blood cells/leukocytes (WBC) Platelets

Plasma 91% water and 9% salts and organic

molecules

Composition of blood

Venipuncture by phlebotomist

Fig. 6.2

Formed Elements

The formed elements are produced in red bone marrow which is found in almost every bone of a child, but in only certain bones of adults. Flat bones of sternum, hips Ends of long bones

Red bone marrow contains pluripotent stem cells, which divide and give rise to all of the various types of blood cells.

Erythrocytes

Red blood cells (RBC)

Discoid shape Biconcave disks

No nucleus Lack many

organelles

RBC

RBC’s are the most abundant formed elements. There are 4 to 6 million red blood cells

per mm3 of whole blood.

RBC’s have 2 main functions. To pick up oxygen from the lungs and

deliver it to tissues of the body. To pick up carbon dioxide from the

tissues and unload it in the lungs.

Red blood cells

They contain many molecules of hemoglobin.

Hemoglobin is a pigment that makes RBC’s red.

Oxygen binds to heme on the hemoglobin molecule

How Red Blood Cells Carry Oxygen

Red blood cells contain hemoglobin, the respiratory pigment that transports oxygen. Each hemoglobin molecule has four

polypeptides that comprise the protein globin and an iron-containing, oxygen-carrying heme portion.

Oxyhemoglobin and deoxyhemoglobin are the names for the shapes that hemoglobin can take with or without bound hemoglobin.

How Red Blood Cells Help Transport Carbon Dioxide

Hemoglobin directly transports about 25% of carbon dioxide which binds to the terminal amino groups of the globin molecules.

The remaining carbon dioxide is transported as the bicarbonate ion in the plasma. The enzyme carbonic anhydrase, contained in red

blood cells, catalyzes the reaction of carbon dioxide and water to form carbonic acid.

When blood containing bicarbonate ions reaches the lungs, carbon dioxide diffuses out of the blood into the lungs and is exhaled.

RBC life cycle Last about 120 days

As a RBC ages, its membrane becomes fragile. Eventually it ruptures as it tries to flex through

narrow capillaries. RBC’s are destroyed in the liver and the

spleen The spleen= the erythrocyte graveyard

RBC’s have a hard time passing through its small channels.

Here the old cells become trapped, broken up, and destroyed.

RBC life cycle

RBC life cycle Hemoglobin is released when blood

cells are broken down. Iron is recovered and recycled to the bone

marrow. Pigments from hemoglobin are excreted as

bile pigments. The kidneys release the erythropoietin

hormone which stimulates bone marrow stem cells to make more red blood cells.

Disorders of RBC’s

Anemia A condition resulting from too

few RBC’s or hemoglobin that causes a run-down feeling

Sickle-Cell Disease Sickle-cell disease is a

hereditary condition in which the hemoglobin molecule is abnormal and the individual has sickle-shaped red blood cells that tend to rupture as they pass through the narrow capillaries.

Disorders of RBC’s

Hemolytic disease of the newborn A condition with

incompatible blood types that leads to rupturing of blood cells in a baby before and continuing after birth

White Blood Cells

White Blood Cells White blood cells (leukocytes) are large,

nucleated, and function in immunity.

Some live days and others live months or years. Memory cells last for decades!

WBC’s are not as numerous as RBC’s Colony-stimulating factors (CSFs) are

proteins that regulate the production of white blood cells.

White Blood Cells

Functions of WBC’s Found in the blood as well as tissues

Can squeeze through pores in the capillary wall to go and fight infections (diapedesis)

Invade tissues when needed Fight infection

Important part of the immune system Numbers can double within hours if needed

White Blood Cells

The immune system defends the body against pathogens, cancer cells, and foreign proteins. An antigen is a cell or other foreign

substance that provokes an immune response. For example:

Foreign proteins Viruses Bacteria Abnormal or foreign cells

How do blood cells leave circulation?

Diapedesis

WBC types

Agranulocytes Lymphocytes Monocytes

Granulocytes Neutrophils Eosinophils Basophils

Neutrophils

Most numerous WBC Contains a multi-lobed

nucleus Fight off bacterial

infections Upon infection they

move out of circulation into tissues to engulf pathogens

Lymphocyte

2nd most numerous WBC Develops into B and T cells

that are important in the immune system B lymphocytes mature into

plasma cells that make antibodies

T lymphocytes control immune response

Important in fighting off viral infections

Monocyte

Largest of the WBC’s Count increases in

inflammation and viral infections

Leave the bloodstream and transform into macrophages Play a role in immune

response

Eosinophils

Small percentage of WBC’s

Many large granules function in parasitic infections and play a role in allergies

Basophils

Smallest percentage of WBC’s

Release histamine related to allergic reactions

Histamine dilates blood vessels and constricts air tubes leading to lungs

Disorders of WBC’s

Severe combined immunodeficiency disease (SCID) An inherited disease in which stem cells of WBC’s lack

an enzyme that allows them to fight any infection

Lymphoma A group of cancers that begin in cells of the immune

system. There are two basic categories of lymphomas: Hodgkin lymphoma and non-Hodgkin lymphomas, which includes a large, diverse group of cancers of immune system cells.

LeukemiaA group of cancers in which white blood

cells proliferate without control

Disorders of WBC’s

Infectious mononucleosis- also know as the “kissing disease” occurs when the Epstein-Barr virus (EBV) infects lymphocytes resulting in fatigue, sore throat, and swollen lymph nodes

50% monocytes with at least 10% atypical lymphocytes (large, irregular nuclei),

Platelets

Platelets

Small fragments of megakaryocytes

Aide in blood clotting

Live for about 10 days

About 200 million are made per day

Platelets and Blood Clotting

Blood Clotting When tissues are damaged, platelets stick

to the damaged area, partially sealing torn blood vessels.

Injured tissues release prothrombin activator, which converts prothrombin to thrombin.

This step requires calcium ions. Thrombin functions as an enzyme to convert

fibrinogen into long threads of insoluble fibrin.

Disorders of Platelets Thrombocytopenia

A disorder in which the number of platelets is too low due to not enough being made in the bone marrow or the increased breakdown outside the marrow

Thromboembolism A spontaneous clot is called a thrombus if it remains

in the vessel; if it dislodges and travels, it is called an embolus.

A thromboembolus can result in a heart attack or stroke when the clot plugs a vessel in the heart or brain

Disorders of Platelets

Hemophilia Hemophilia is an inherited clotting

disorder carried on the X chromosome which results in the deficiency of a clotting factor. Injections of this factor can treat the disease.

Victim hemorrages Can die from bleeding internally

Blood Typing A blood transfusion is the transfer of blood

from 1 individual to another For transfusions to be safe, blood must be

typed so that agglutination (clumping) does not occur Blood typing involves determining the ABO blood

group and Rh factor so that the transfusion can be done safely.

Blood typing usually involves determining the ABO blood group and whether the individual is Rh- or Rh+

ABO Blood Groups The most common system for typing blood

is the ABO system. Blood types A, B, and AB correspond with

having specific antigens on the surface of RBCs; type O is an absence of these antigens.

All persons have antibodies in their plasma for the A and/or B antigen not carried on their own RBCs.

If the corresponding antigen and antibody are combined, clumping, or agglutination, occurs.

Blood typing

For example: Type A blood-has A antigen on its surface-has B antibodies in the plasma

What can you say about someone with type AB blood?

Blood types

Plasma

Determining compatibility for blood transfusion

First consider the antigens found on the blood transfusion recipient

Second, consider the antibodies found in the donor blood

If the antibodies in the donor blood can recognize the antigen on the recipient’s blood then the blood will agglutinate (clump) and cause rejection

Blood Compatibility

Type O blood is sometimes called the universal donor because the red blood cells of type O blood lack A and B antigens.

Type O blood will not agglutinate regardless of the recipient’s antibodies.

Blood Compatibility

Type AB blood is called the universal recipient because the plasma lacks A and B antibodies

Type AB recipient blood won’t clump with any type of donor blood

Testing your understanding

Can a person with blood type O accept blood type A without agglutination occurring?

Why can people with AB blood type accept more blood types than people with type O, A, or B?

Which blood type is able to be used most often as a donor blood type?

Rh blood groups

The Rh factor is often included when expressing a blood type by naming it positive or negative

People with the Rh factor are positive and those without it are negative

Rh antibodies only develop in a person when they are exposed to the Rh factor from another’s blood (usually a fetus)

When is Rh Factor Important During pregnancy under these conditions:

Mom: Rh-Dad: Rh+Fetus: Rh+

In this case some Rh+ blood can leak from the fetus to the Mom during birth causing the mother to make Rh antibodies

When is Rh factor Important

This can be a problem is the mother has a 2nd fetus that is Rh+ because she now has antibodies that can leak across the placenta and attack the fetus

This condition is known as hemolytic disease of the newborn that can lead to death

Hemolytic Disease of Newbornor Erythroblastosis fetalis

Can be fatal Can cause jaundice

because of degrading hemoglobin in blood

Hemolytic Disease Prevention Rh- women are given an injection of

anti-Rh antibodies no later than 72 hours after birth to an Rh+ baby

These antibodies attack fetal red blood cells in mother before the mother’s immune system can make antibodies

This will have to be repeated if an Rh- mother has another Rh+ baby in case she has later pregnancies

http://pneupnurse.tumblr.com/image/31054609864

AB incompatibility

< 20% of all pregnancies Anti-A and anti-B antibody molecules

are IgM and therefore very large Do not cross placenta Do not cause hemolytic disease

IgG is occasionally produced and does cross placenta causing hemolytic disease

EC Reports-1 Discuss the problems with athletes and blood doping.

Is this legal? What are the advantages? What are the disadvantages? Some athletes have been stripped of their medals because

they tested positive for performance-enhancing substances in their blood. Why would someone use such a drug if they knew they could be caught and disqualified from the competition? How do the Olympics keep ahead of the new methods for illegally enhancing performance?

Why do so many of our US Olympic teams train at high altitudes?

EC Reports-2 Discuss the use of stem cells from the blood

in the treatment of leukemia and other blood diseases.

How successful is this? How is it done? What types of stem cells are used? Why would parents choose to save cord

blood? What diseases can be treated with cord blood? What are the costs associated with saving cord

blood?

EC Reports-3 Read BIOLOGY MATTERS-Health “Aspirin and

Heart Disease” on page 122 of the text. Recount the differences between a negative and a positive feedback mechanism. Have students discuss the advantages and disadvantages of inhibiting the activity of thromboxane.

If a family member has had a stroke or strokes, would you consider taking daily baby aspirins as you would a vitamin supplement?