APHY102 - marieb - Chapter 17 - blood

What's the body's only fluid tissue?

Blood

Blood is the body's only ____ tissue.

Fluid

What are the two basic components of blood?

Liquid plasma and formed elements

What are the three primary formed elements of blood?

1. Erythrocites (red blood cells or WBCs)

2. Leukocytes (white blood cells or WBCs)

3. Platelets

When stratified by a centrifuge, what are the three layers of whole blood?

1. Plasma - 55%

2. Buffy coat (less than 1% - leukocytes and platelets)

3. Erythrocytes - 45%

What's the pH of blood?

7.35-7.45

What's the temperature of blood?

38 degrees Celsius, or 100.4 degrees Fahrenheit

What percentage of body weight does blood make up?

about 8%

How many liters of blood does the average male contain?

5-6L

How many liters of blood does the average female contain?

4-5L

Generally speaking, what four things does blood transport?

1. Oxygen from the lungs

2. Nutrients from the digestive tract

3. Metabolic waste from cells to the lungs and kidneys for elimination

4. hormones from endocrine glands to target organs

What three factors does blood maintain?

1. Appropriate body temperature by absorbing and distributing heat

2. Normal pH in body tissues using buffers

3. Adequate fluid volume in circulatory system

How does blood prevent blood loss?

By activating blood proteins and platelets, and by initiating clot formation when a vessel is broken

How does blood prevent infection?

By synthesizing and utilizing antibodies, by activating complement proteins, and by activating WBCs to defend the body against foreign invaders

What percentage of blood plasma is water?

90%

What color is blood plasma?

straw-colored

How many different solutes does blood contain?

over 100

What are the five main categories of solutes found in blood plasma?

1. Proteins (albumin, globulins, clotting proteins and more)

2. Nonprotein nitrogenous substances (lactic acid, urea, creatinine)

3. Organic nutrients (glucose, carbohydrates, amino acids)

4. Electrolytes (sodium, potassium, calcium, chloride, bicarbonate)

5. Respiratory gases (oxygen and CO2)

Of all the formed elements of blood, which ones are the ONLY complete cells?

WBCs (leukocytes)

Why aren't RBCs (erythrocytes) considered full cells?

They have no nuclei or organelles

Why aren't platelets considered full cells?

Well, they're just cell fragments

How long do formed elements survive in the blood?

Generally a few days

How are blood cells renewed?

They don't divide; rather they are replenished by cells in bone marrow

What does hematopoiesis mean?

blood cell formation

What's the scientific term for "blood cell formation?"

Hematopoiesis

Within the red bone marrow of which bones does hematopoiesis occur?

Axial skeleton and girdles, epiphyses of humerus and femur

What cells give rise to ALL formed elements of blood?

Hemocytoblasts

What are hematocytoblasts?

Blood stem cells --- they give rise to ALL formed elements of blood.

Where are blood cells formed in an EMBRYO?

Yolk sac, liver, spleen, thymus, lymph nodes, red bone marrow

Where are blood cells formed in an ADULT?

Only in the red bone marrow of bones such as the sternum, ribs, skull, pelvis, and ends of long bones

What's erythropoiesis?

It's the process by which RBCs (erythrocytes) are produced.

Usually happens in bone marrow (in adults)

What's the scientific term for the process by which RBCs (erythrocytes) are produced?

Erythropoiesis

What's leukopoiesis?

The formation and development of white blood cells.

What's the scientific term for the formation and development of white blood cells?

Leukopoiesis

What's thrombopoiesis?

It's a term used interchangeably for:

1. Blood clot formation

2. Blood platelet formation

What's the term used to describe blood clot formation and/or the formation of platelets?

Thrombopoiesis

What shape are RBCs (erythrocytes)?

Biconcave discs (flattened discs with depressed centers --- think of a donut with the middle hole not TOTALLY gone)

What DON'T erythrocytes have that most other cells have?

nuclei and organelles

What key protein aids in erythrocytes' flexibility and ability to take shape?

Spectrin

Besides water, what is the MAIN component of erythrocytes?

Hemoglobin (Hb) -- it's 97% of the cell's content if you discount water content

What does hemoglobin consist of?

four (4) polypeptide chains (or globin molecules) and four (4) heme groups

What role do the globin molecules in hemoglobin play?

They transport carbon dioxide (carbonic anhydrase involved), and nitric oxide

What role do the heme molecules in hemoglobin play?

Oxygen transport

What mineral is required for oxygen transport?

Iron

What's Oxyhemoglobin?

Hemoglobin bound to oxygen

What term is defined as "hemoglobin bound to oxygen?"

Oxyhemoglobin

In regard to hemoglobin, where does oxygen loading take place?

Lungs

What's deoxyhemoglobin?

Hemoglobin AFTER oxygen diffuses into tissues (reduced Hb)

What term is defined as "Hemoglobin after oxygen diffuses into tissues?"

Deoxyhemoglobin

With regard to hemoglobin, where does carbon dioxide loading occur?

Tissues

In the first step of erythropoiesis (the creation of an erythrocyte), a hemocytoblast is transformed into a committed cell called what?

proerythroblast

Whats a proerythroblast?

It's the committed cell that WAS a hematocytoblast and WILL be an erythroblast

Once an proerythroblast develops into an erythroblast, what are the four steps of the developmental pathway?

Phase 1) Ribosome synthesis in early erythroblasts

Phase 2) Hemoglobin accumulation in late erythroblasts and normoblasts

Phase 3) Ejectrion of the nucleus from normoblasts and formation of reticulocytes

Phase 4) Reticulocytes develop into mature erythrocytes

What is erythropoietin (EPO)?

EPO (erythropoietin) is a hormone, created in the kidneys, that increases the RBC count in circulating blood and improves the oxygen carrying ability of the blood

What stimulates erythropoietin production?

Hypoxia due to decreased RBC count, decreased availability of O2 to blood, or increased tissue demands for O2

What's the lifespan of an erythrocyte?

100-120 days

What happens when an erythrocyte gets old?

It becomes rigid and fragile, and its hemoglobin degenerates. It is then engulfed by macrophages, which separate heme from globin and reuse the iron. Heme degrades to bilirubin.

What happens after the liver secretes bilirubin-rich bile?

The intestines metabolize it into urobilinogen

What happens to globin after the death of an erythrocyte?

It is metabolized into amino acids which are released into circulation

What happens to hemoglobin released into the blood?

It's captured by haptoglobin and phagocytized

What's anemia?

When the blood has abnormally low oxygen-carrying capacity -- it's a symptom, not a disease, and it interferes with metabolism. Symptoms include fatigue, paleness, chills and shortness of breath.

If a person's blood has abnormally low oxygen-carrying capacity, what erythrocyte disorder does he/she have?

Anemia (which is an indicator of greater health problems)

What three types of anemia are due to insufficient erythrocites?

1. Hemorrhagic anemia (result of acute/chronic loss of blood)

2. Hemolytic anemia (prematurely ruptured erythrocytes)

3. Aplastic anemia (destruction or inhibition of red bone marrow)

What two types of anemia are due to abnormal hemoglobin?

1. Thalassemia (absent or faulty globin chain, result is thin, delicate, hemoglobin-deficient erythrocytes)

2. Sickle-cell anemia (results from a defective gene coding for an abnormal hemoglobin called hemoglobin S [HbS] -- HbS has a single amino acid substitution in the beta chain that causes the RBCs to be sickle-shaped in low-oxygen situations)

What's Polycythemia?

Excess RBCs that increase blood viscosity.

What term is defined as "A condition characterized by presence of excess RBCs that increase blood viscosity?"

Polycythemia

What's polycythemia vera?

A chronic blood disorder in which RBCs are overproduced, creating sludgy, clot-prone blood.

What disease-related condition does "a chronic blood disorder in which RBCs are overproduced, creating sludgy, clot-prone blood" describe?

Polycythemia vera

What type of polycythemia is caused when less oxygen is available (such as high-altitude situations?)

Secondary polycythemia (treated with blood dilution by saline)

What do you call human-induced polycythemia practiced by some athletes?

Blood doping

Carbaminohemoglobin is what, exactly?

It's a compound of hemoglobin (Hb) and carbon dioxide.

What is the term for a compound of hemoglobin and carbon dioxide?

Carbaminohemoglobin

What's BC (hematocrit)?

It's the percentage of red blood cells in the blood. Normal values are: Male: 39%-49% Female: 33%-43%

What term describes the percentage of red blood cells in the blood?

BC, or Hematocrit

What percent of total blood volume is made up of leukocytes?

1 percent

What is diapedesis?

The passage of blood cells through capillary walls to tissues -- also called emigration

Through what process can blood cells pass into body tissues?

Diapedesis

What is leukocytosis?

An increase in the number of white blood cells. A standard measure against infection. WBCs can number 11,000 in one cubic millimeter.

What's amoeboid movement?

Movement resembling that of an ameba, specifically changing shape through protoplasmic flow. Phagocytic leukocytes move this way and engulf damaged cells and invading cells

What is chemotaxis?

The organization or movement of an organism or cell in relation to chemical agents. Used to describe the way that immune cells "move toward the smell" and find and destroy bacteria and viruses.

What is the blood's first line of defense against bacterial infections?

Neutrophils. These are the chief phagocytic WBCs. They are a type of granulocyte.

By what process can neutrophils and other WBCs locate and converge on bacteria?

Chemotaxis

What's a granulocyte?

WBCs that have a cytoplasm that contains tiny granules.They're named according to the staining characteristics of these granules. Neutrophils are granulocytes.They stain specifically with Wright's stain, are larger and shorter-lived than RBCs (erythrocytes), are phagocytic, and have lobed nuclei.

What are the three types of granulocytes?

Neutrophils, eosinophils, and basophils.

Neutrophils have two types of granules that:

give the cytoplasm a lilac color, take up both acidic and basic dyes, and contain peroxidases, hydrolitic enzymes, and defensins (antibiotic-like proteins)

What cells are our bodies' bacteria slayers?

Neutrophils

What percentage of our WBCs are eosinophils?

1%-4%

What are eosinophils' two main purposes?

1. Assault against parasitic worms

2. Lessening the severity of allergies by phagocytizing immune complexes.

What color are eosinophils before and after dying? What kind of dyes do they respond to best?

Eosinophils are naturally transparent. They are "acid-loving" and dye brick red with acidic dyes (specifically eosin).

What percentage of WBC count is made up of basophils?

0.5%

Describe the characteristics of basophils.

They have U or S shaped nuclei with two or three conspicuous constrictions. They are functionally similar to mast cells. Basophils have large, purple-black basophilic granules that contain histamine.

What does histamine do?

Histamine is an inflammatory chemical that attracts other WBCs and act as a vasodilator. It also increases capillary permeability to WBCs to assist in immune function.

What's an agranulocyte?

A category of WBCs that lack visible granules.

What are the two types of agranulocytes?

Lymphocytes (spherical nuclei) and monocytes (kidney-shaped nuclei)

What percentage of WBCs are lymphocytes?

25% or more

What do lymphocytes look like?

Like most cells, translucent, but after dyeing, lymphocytes have large, dark-purple circular nuclei surrounded by a thin rim of blue cytoplasm.

What are the two types of lymphocytes?

T cells and B cells

Where are most lymphoid cells located?

Most are enmeshed in lymphoid tissue, while some are present in the blood.

What do T-cells do?

They function in the immune response. T-cells have "T-cell receptors" which react with antigens and MHC and activate.

What do B-cells do?

B cells give rise to plasma cells which produce antibodies.