blood

The only fluid tissue in the human body Classified as a connective tissue Components of blood

◦ Living cells Formed elements: basophils, eosinophils,

erythrocytes, lymphocytes, megakaryocytes, monocytes, neutrophils

◦ Non-living matrix Plasma: primarily water, non-cellular; the fluid matrix

of blood

If blood is centrifuged1. Erythrocytes sink to the

bottom (45% of blood, a percentage known as the hematocrit)

2. Buffy coat contains leukocytes and platelets (less than 1% of blood)

Buffy coat is a thin, whitish layer between the erythrocytes and plasma

3. Plasma rises to the top (55% of blood)

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Found in PlasmaNutrients: • Glucose, fatty acids• vitamins• amino acidsGases:

O2 , CO2Ions:• Sodium• Potassium• Calcium

Figure 10.1 (2 of 2)

Three major categories ofFormed Elements:•Erythrocytes•Leukocytes•Platelets

Color range◦ Oxygen-rich blood is scarlet red◦ Oxygen-poor blood is dull red

pH must remain between 7.35–7.45 Blood temperature is slightly higher than

body temperature at 100.4°F In a healthy man, blood volume is about 5–6

liters or about 6 quarts Blood makes up 8% of body weight

Composed of approximately 90% water Includes many dissolved substances

◦ Nutrients◦ Salts (electrolytes)◦ Respiratory gases◦ Hormones◦ Plasma proteins◦ Waste products

Plasma proteins◦ Most abundant solutes in plasma◦ Most plasma proteins are made by liver◦ Various plasma proteins include

Albumin—regulates osmotic pressure Clotting proteins—help to stem blood loss when a

blood vessel is injured Antibodies—help protect the body from pathogens

Acidosis◦ Blood becomes too acidic

Alkalosis◦ Blood becomes too basic

In each scenario, the respiratory system and kidneys help restore blood pH to normal

Erythrocytes ◦ Red blood cells (RBCs)

Leukocytes ◦ White blood cells (WBCs)

Platelets Cell fragments

1. Which body organ plays the main role in producing blood proteins?

2. What are the three major categories of formed elements?

3. What determines whether blood is bright red (scarlet) or dull red?

4. What is the blood volume of an average-sized adult?

5. Name as many different categories of substances carried in plasma as you can.

6. Define formed elements. Which category is most numerous? Which makes up the buffy coat?

Figure 10.2

Table 10.2 (1 of 2)

Table 10.2 (2 of 2)

Erythrocytes (red blood cells or RBCs)◦ Main function is to carry oxygen◦ Anatomy of circulating erythrocytes

Biconcave disks Essentially bags of hemoglobin Anucleate (no nucleus) Contain very few organelles

◦ 5 million RBCs per cubic millimeter of blood

Hemoglobin◦ Iron-containing protein◦ Binds strongly, but reversibly, to oxygen◦ Each hemoglobin molecule has four oxygen

binding sites◦ Each erythrocyte has 250 million hemoglobin

molecules◦ Normal blood contains 12–18 g of hemoglobin per

100 mL blood

Hemoglobin transports oxygen in the blood as well as a small amount of carbon dioxide.

Homeostatic imbalance of RBCs◦ Anemia is a decrease in the oxygen-carrying

ability of the blood◦ Sickle cell anemia (SCA) results from abnormally

shaped hemoglobin◦ Polycythemia is an excessive or abnormal

increase in the number of erythrocytes

Table 10.1

Figure 10.3

Leukocytes (white blood cells or WBCs)◦ Crucial in the body’s defense against disease◦ These are complete cells, with a nucleus and

organelles◦ Able to move into and out of blood vessels

(diapedesis)◦ Can move by ameboid motion◦ Can respond to chemicals released by damaged

tissues◦ 4,000 to 11,000 WBC per cubic millimeter of

blood

Abnormal numbers of leukocytes◦ Leukocytosis

WBC count above 11,000 leukocytes/mm3

Generally indicates an infection◦ Leukopenia

Abnormally low leukocyte levelCommonly caused by certain drugs such as corticosteroids and anticancer agents

◦ LeukemiaBone marrow becomes cancerous, turns out excess WBC

Types of leukocytes

◦ Granulocytes Granules in their cytoplasm can be stained Possess lobed nuclei Include neutrophils, eosinophils, and basophils

◦ Agranulocytes Lack visible cytoplasmic granules Nuclei are spherical, oval, or kidney-shaped Include lymphocytes and monocytes

List of the WBCs from most to least abundant◦ Neutrophils◦ Lymphocytes◦ Monocytes◦ Eosinophils◦ Basophils

Easy way to remember this list◦ Never◦ Let◦ Monkeys◦ Eat ◦ Bananas

Figure 10.4

Hemocytoblaststem cells

Secondary stem cells

Basophils

Eosinophils

NeutrophilsMonocytesLymphocytes

Erythrocytes

Platelets

Lymphoidstem cells

Myeloidstem cells

Figure 10.4, step 1

Hemocytoblaststem cells

Figure 10.4, step 2

Hemocytoblaststem cells

Secondary stem cell

Lymphoidstem cells

Figure 10.4, step 3

Hemocytoblaststem cells

Secondary stem cell

Lymphocytes

Lymphoidstem cells

Figure 10.4, step 4

Hemocytoblaststem cells

Secondary stem cells

Lymphocytes

Lymphoidstem cells

Myeloidstem cells

Figure 10.4, step 5

Hemocytoblaststem cells

Secondary stem cells

Basophils

Eosinophils

NeutrophilsMonocytesLymphocytes

Erythrocytes

Platelets

Lymphoidstem cells

Myeloidstem cells

Types of granulocytes◦ Neutrophils

Multilobed (3-7 lobes) nucleus with fine granules Act as phagocytes at active sites of infection Name means “neutral-loving”

◦ Eosinophils Large brick-red cytoplasmic granules Found in response to allergies and parasitic worms

Types of granulocytes (continued)◦ Basophils

Have histamine-containing granules Initiate inflammation Releases a vasodilator; least abundant WBC

Types of agranulocytes◦ Lymphocytes

Nucleus fills most of the cell Play an important role in the immune response

◦ Monocytes Largest of the white blood cells Function as macrophages Important in fighting chronic infection Phagocyte in chronic infections

Platelets◦ Derived from ruptured multinucleate cells

(megakaryocytes) ancestral cell of platelets◦ Needed for the clotting process◦ Normal platelet count = 300,000/mm3

7. What is the role of hemoglobin in the red blood cell?

8. Which white blood cells are most important in body immunity?

9. If you had a severe infection, would you expect your WBC count to be closest to 5,000, 10,000 or 15,000/mm3.

10. Little Lisa is pale and listless. What disorder of erythrocytes might she be suffering from?

11. Define anemia, and give three possible causes.

12. Name the granular and agranular WBCs. Give the major function of each type in the body.