Biology 2404 A&P Basics

The cells of blood are called formed elements, the fiber is the clotting protein called fibrin, and the ground substance is a fluid called plasma. Blood is transported in vessels that create vascular circuits in order to distribute substances to the proper organs. Pressure gradients allow for blood flow and are initiated by the heart muscle contractions. Together, the blood, vessels, and heart form the cardiovascular system.

The general functions of blood are transportation, regulation, and protection.

Transportation of nutrients, waste products, gases, and hormones

Regulation of ion balance, acid-base (pH) balance, and temperature

Protection by blood clotting to prevent hemorrhage

Protection by white blood cells for immune defense

General Characteristics:

Volume of blood in humans is ~ 5 liters

of which 45% is composed of solutes (solids) and 55% solvent (liquid)

pH of blood ranges from 7.35-7.45 (for venous and arterial blood, respectively)

viscosity or thickness of blood is 3-5 times that of water

Blood as a Connective Tissue

RBCs and WBCs

Blood Components

A. Plasma

Makes up 55% of the blood volume

90% is water

10% are composed of dissolved substances

~7% are proteins such as hormones, globulins (alpha, beta gamma), and albumin

along with clotting factors such as prothrombin and fibrinogen

The remaining 3% of plasma is conprised of

respiratory gases such as O2 and CO2

                        ions such as Na+, K+, Ca++, Cl-, HCO3-

                        nitrogen wastes such as urea and uric acid

                        nutrients such as glucose and amino acids

Functions in transport and regulation

Histology

Serum in Tube

Whole Blood in EDTA tube

B. Formed Elements : Red Blood Cells

All blood cells (formed elements) come from the hemopoietic tissue located in the spongy region that forms the red bone marrow and lymphatic tissue found in the lymph nodes, spleen, and thymus. Stem cells in the red bone marrow create most of the blood cells and the formation process is under hormonal control. Some of these blood cells will migrate to the lymphatic tissues and under immune signals, can create additional products or defense cells. The normal adult blood cells are red blood cells, white blood cells, and the formed elements: platelets.

Red Blood Cells (erythrocytes, RBCs)

RBCs come from the stem cell’s myeloid cell line and production regulation is under the influence of the hormone Erythropoeitin (EPO). EPO is made in the kidneys in response to low O2 levels. Maturation of erythrocytes takes approximately one week and is dependent on several B vitamins such as B12 and folic acid. Immature RBCs such as reticulocytes or nucleated RBCs can sometimes be seen in a blood smear and are important indicators of bone marrow response in blood loss conditions.

Mature human red blood cells are biconcave discs about 8 µm in size in order to fit single file through a capillary bed. They appear clear in color when seen on a wet mount, but red in color when observed during collection or on a stained smear. A mature RBC has lost all its organelles including the nucleus and ribosomes, and contains only hemoglobin protein molecules and some enzymes such as carbonic anydrase. Most RBC enzymes are located on the plasma membrane and function in transport of nutrients into the cell or to maintain plasma membrane integrity. Because they can not repair their cell membranes, the lifespan of a RBC is only about 120 days. Old, fragile red blood cells are recycled by the tissue macrophage (reticuloendothelial) system in the liver and spleen. Most of the hemoglobin is reused, but the pigment portion contains nitrogen and is eventually converted to a waste product called bilirubin.

Normal RBC count is between 4.5 – 6.0 cubic millimeters and makes up almost 45% of the blood volume. These cells function to carry respiratory gases and help control blood pH by acting as a buffer that ties up hydrogen ion. A blood test used to determine the percentage of red blood cells is the hematocrit or HCT. This the percentage is calculated based on other information such as RBC number and MCV (mean corpuscular volume). If the % RBC is dtermined by spinning down a blood capillary tube and read using a scale, it is called the packed cell volume or PCV.

Another test performed using RBCs is blood typing. Blood types are genetically determined proteins that are on the cell membrane as an immune marker. The most important proteins to identify belong to the ABOD grouping. If these proteins interact, they can cause severe, even life threatening problems. The ABO group contains proteins identified as Type A, Type B, Type AB, and Type O blood. These proteins are self antigens and stimulate the immune system to make defense proteins called antibodies. The immune system makes antibodies to the antigen of the protein NOT found on the RBC and the antibodies then circulate in the plasma. For example, Type A blood will have anti-B antibodies and Type B blood will have anti-A antibodies. Type AB blood has no plasma antibodies and type O blood has both anti-A and anti-B antibodies. Other names you may see used are agglutinogens for the RBC antigen and agglutinins for the plasma antibodies.

Blood typing also identifies the D antigen known as the Rh factor. If the RBC has the dominant “D” antigen, the blood is identified as Rh+. If the antigen is the recessive “d”, the blood type is identified as Rh-. There are other Rh antigens, but they do not cause severe transfusion reactions. The blood tests performed to identify blood types are called typing and cross matching. Blood typing is determined by an agglutination reaction on the slide between the donor’s red blood cells and the recipient’s plasma antibodies. Cross matching looks for any agglutination between the recipients red blood cells and the donor’s plasma antibodies.

RBC drawing

Red Blood cells in different types of solutions: No solution, Isotonic, Hypotonic, Hypertonic

Blood Transfusion Bag

C. Formed Elements: White Blood Cells (leukocytes, WBCs)

White blood cells come from either the myeloid cell line or the lymphocytic cell line. Production regulation is under the influence of various hormones called colony stimulating factors known as colony stimulating factors, or CS-F.

Leukocytes average about 5-9 thousand per cubic millimeter of blood and the 5 different WBC types are divided into two major classes that help to identify them in when a differential white cell count is performed. The two groups of WBCs are granulocytes and agranulocytes.

Granulocytes are approximately the same size as a RBC. Their nucleus is divided into at least two segments or parts and their cytoplasm contains granules that give them their function. The granulocytes consist of:

Neutrophils 3-5 lobed nucleus, neutral staining granules

Function in nonspecific, general defenses, acute phagocytosis

70% of the WBC count, Life span 12-24 hours

Eosinophils 2 lobed nucleus, pink staining granules

Functions in specific defenses for allergens antigens

3% of WBC count, life span varies

Basophils 2 lobed nucleus, blue staining granules

Functions in specific defenses for allergens (Type I hypersensitivities) and antigens on parasites

0.5-1% of WBC count, life span varies

Agranulocytes do not contain granules in their cytoplasm and the size and nucleus varies. The agranulocytes are:

Lymphocytes round nucleus, small amount of cytoplasm, 20 % of the WBC count

Three sizes= small, medium, large. Medium is the same size as a RBC.

Some large lymphocytes function in nonspecific defenses as Natural Killer cells

Most function in specific defenses as T cells or B cells

Life span varies, sometimes life long

Macrophage bean shaped nucleus, large amount of cytoplasm,

8-10% of WBC count (monocytes in the blood move to the tissues to mature into macrophages)

2-3 x the size of a RBC.

Nonspecific defense that ties to specific defenses, Antigen Presenting Cell (APC)

Life span varies, sometimes life long

Fixed or Free (wandering) macrophages

Drawings:

Granulocytes

Agranulocytes

Histology of WBC

WBC Differential Blood report

WBCs mixed

Neutrophils
Monocytes
Eosinophil with Monocyte
Basophil

D. Formed Elements: Platelets

Platelets or thrombocytes are packages of enzymes that come from fragments of megakaryocyte cells located in the red bone marrow. Production regulation is under the influence of the hormone thrombopoietin (TPO). Life span of platelets is about 10 days.

The normal platelet count is 150-400 thousand per cubic milliliter of blood.

Enzymes contained in the membrane sac function to aid in the clotting mechanisms

Red Bone Marrow

Drawing of Platelets

Histology of Platelets

Blood Tests

CBC : Equipment

PCV: Equipment

HCT : Drawing, Photo , Drawing 2

E. Hemostasis

Hemostasis is the control and stoppage of blood loss. It is under positive feedback control and once started should go to completion and end the cycle. The four phases of hemostasis are:

1. Vascular spasm: When a vessel is injured, the smooth muscle in the wall constricts.

Collagen is exposed due to the injury and vascular chemotaxis chemicals are released.

2. Platelet Plug: Platelets are attracted to the injured vessel by chemicals and the rough surface of the

collagen causes the platelets to enlarge and become sticky. The platelets form a temporary

barrier to close off the opening in the vessel and then release factors that attract other

platelets to the area.

3. Coagulation: Clotting factors in the plasma are activated by the roughened vessel surface and the platelet plug. Two pathways of coagulation are then activated.

One phase called the extrinsic pathway takes about a minute and the second called the intrinsic pathway takes longer, at approximately 3 minutes.

The end result of both coagulation phases is the formation of fibrin from the clotting factor,

fibrinogen. Fibrin strands are stabilized and form a mesh or net at the injury site.

This fibrin mesh traps RBCs to help form the blood clot.

4. Clot Retraction and Resolution: Once the injury site is closed off, the clot retracts to pull the

vessel lining together. Once the site is repaired, the blood clot is no longer needed.

Chemicals are released to cause fibrinolysis and the clot is dissolved.

Clot Tube

Equipment: stain, blood tubes, centrifuge, refractometer

Blood Transfusion Kit

Blood Web Site : click on specific formed elements of blood

Medical Terminology

Erythema- flushed pan- all

Erythr/o-. rubr/o- red -penia lack

Leuk/o- white -phil, -philia love

Macro- large -poiesis make

Mono- single -rrhage flow

-osis abnormal condition bol- throw

sanguin/o- blood thromb/o- clot

hemat/o- blood -crit separate

Exercises/Activities

A) Drawings of Blood cells to ID

B) Histology ID of Blood cells

C) ID parts of HCT

D) Blood type Scenario (go to this web site and treat your patient!)

E) Specimen : Identify region labeled

F) CBC reports to analyze: Report # 1, Report # 2 , Report #3

G) Blood type genetics

Blood lab (click here to quiz yourself on blood)

Concept Map: Make a concept map of the blood (source, cells, location, function). Include this map in your LAR lab report (if selected) as a document insert or as an addtional PDF document scan.

Case Study : Blood

Applications

Anemia: Iron deficiency, Pernicious anemia, Sickle cell anemia, aplastic anemia,

hemolytic anemia, Folic Acid Deficiency anemia,

Polycythemia Vera

Jaundice: hepatic, prehepatic, hemolytic, posthepatic, obstructive

Hemolytic disease of the newborn (erythroblastosis fetalis)

Leukemia: acute lymphocytic leukemia (ALL), chronic myeloid leukemia, acute monoblastic,

Acute myeloblastic leukemia (AML), chronic lymphocytic leukemia (CLL)

Thrombus, Embolism

Hemophilia

Thalassemia

Malaria

Infectious Mononucleosis

Leukocytosis

Neutrophilia, Neutropenia

Eosinophilia, Eosinopenia

Basophilia

Macrocytosis

Lymphocytosis, Lymphopenia

Thrombocytosis, Thrombocytopenia

Bone Marrow Transplant

Careers:

Phlebotomist

Blood Bank Technician

WWW

http://www.lumen.luc.edu/lumen/meded/histo/frames/histo_frames.html

http://www.mc.vanderbilt.edu/histo/blood/

http://www.nlm.nih.gov/medlineplus/bloodlymphaticsystem.html

Summary and Review Questions

1. Give four functions of blood

2. Give the composition and % of plasma

3. Give the description and specific functions of RBCs and two tests that can be used using RBCS.

4. Name the RBC antigens and corresponding plasma antibodies for the various blood types.

5. Give the description and specific function for platelets

6. Name each of the five WBCs and give their description and unique function

7. Define hemostasis and name the four stages

8. Define coagulation

9. Explain the difference between agglutination and coagulation

10. Name a hormone that affects blood.