Key Questions for Understanding the Blood

What substances does blood transport through blood vessels?

Nutrients Wastes Body heat

2. Blood is the only fluid body tissue.

What are formed elements? What is plasma?

Formed elements are living cells

Plasma is a nonliving fluid matrix

What are erythrocytes?

Erythrocytes are red blood cells that function in oxygen transport

What is the buffy coat? What are leukocytes? What are platelets? The buffy coat is a thin, whitish layer

formed at the junction of formed elements and plasma

Leukocytes are white blood cells that act in various ways to protect the body

Platelets are cell fragments that function in the clotting process

Percentages of Blood Volume by components:

Plasma: 55%Red Blood Cells: 44.2%Leukocytes and Platelets: <1%

What are plasma proteins? Where are they made?

Plasma proteins are the most abundant solutes in plasma. They are made in the liver.

How do red blood cells differ from other blood cells?

Red blood cells are anucleate; that is, they do not have a nucleus

What is hemoglobin?

Hemoglobin is an iron-containing protein that transports most of the oxygen carried in the blood.

How many molecules of O2 can each RBC carry?

Each RBC can carry 1 billion molecules of oxygen

12-18 grams of hemoglobin are found in each 100 mL of blood

What is anemia? What 2 conditions can cause anemia? Anemia is a decrease in the oxygen-

carrying ability of the blood. Anemia is caused by lower than

normal numbers of RBC’s or abnormal or deficient hemoglobin content

Who usually suffers from sickle-cell anemia? Why?

Black people who live in the malaria belt of Africa, and their descendents, usually suffer from sickle-cell anemia.

The same gene that causes sickling makes red blood cells infected with malaria die and prevents them from multiplying

What is polycthemia?

Polycthemia is an excessive or abnormal increase in the number of erythrocytes caused by bone marrow cancer or living at high altitudes

This is a problem because of increased blood viscosity

What is diapedesis?

Diapedesis is the ability to slip into and out of the blood vessels from cells of the body.

Describe leukocytosis. Leukocytosis is a total WBC count

above 11,000 cells per cubic millimeter, which indicates that a bacterial or viral infection is beginning in the body

What are the causes and symptoms of leukemia? When bone marrow becomes

cancerous and huge numbers of WBC’s are “turned out” rapidly, the body becomes sensitive to bacteria and viruses because the WBC’s are incapable of normal activities.

Differentiate between the 2 major groups of white blood cellsGranulocytes Agranulocytes1. neutrophils: phagocytes at sites of acute infection

1. lymphocytes: stay in lymphatic tissue, play a role in the immune response

2. eosinophils: # increases during allergies and infections by parasitic worms

2. monocytes: become macrophages that fight chronic infections

3. basophils: contains histamine, which attracts other WBC’s to the inflammatory site

Where does hematopoiesis occur? Hematopoiesis occurs in the myeloid

tissue of red bone marrow In adults, it occurs in the flat bones of

the skeleton and the proximal epiphyses of the humerus and femur

What are hemocytoblasts?

Hemocytoblasts are stem cells that reside in red bone marrow, which can develop into any of the formed elements

Definition of Hemostasis:

Hemostasis is the stoppage of blood flow

3 phases of hemostasis:1. Platelet plug forms: platelets stick to

broken blood vessels2. Vascular spasms occur: spasms

narrow the blood vessel, decreasing blood loss

3. Coagulation occurs: enzymes are released to activate clotting

How long does clotting normally take?

3 to 6 minutes

2 Steps that speed up the clotting process:

1. Placing a sterile gauze over the wound, which provides a rough surface for platelet adhesion

2. Applying pressure fractures cells, which increases the release of thromboplastin

What is a thrombus? Why are they undesirable? A thrombus is a clot that develops

and persists in an unbroken blood vessel.

If large enough, it may prevent blood flow beyond the blockage

What is an embolus? When does it become a problem?

An embolus is a thrombus that floats freely in the bloodstream. It becomes a problem when it lodges in a blood vessel too narrow to pass through.

What causes undesirable clotting?

Anything that roughens the endothelium of a blood vessel and encourages clinging of platelets causes undesirable clotting

What is hemophilia? How can it be controlled?

Hemophilia is a hereditary bleeding disorder that results from a lack of any of the factors needed for clotting. It can be controlled through injections of genetically engineered clotting factors.

What is an antigen? What is agglutination? An antigen is a substance that the

body recognizes as foreign. It stimulates the release of antibodies to attack it.

Agglutination is building of antibodies to RBC’s, which causes them to clog in blood vessels.

Which antigens are inherited for each of the four blood types?Blood Type Antigens Blood Received

AB A,B A, B, AB, O

A A, anti-B A, O

B B, anti-A B, O

O anti-A, anti-B O

Describe the procedure for testing an individual’s ABO blood type:1. Test blood by mixing it with 2

different types of immune serum—anti-A and anti-B

2. Agglutination of the sample with 1, both, or neither of the sera determines blood type