Chapter 17: Blood

What are the 3 main functions of blood?

Distribution, regulation, and protection

What does blood distribute?

• O₂ & nutrients to body cells

• Metabolic wastes to the lungs & kidneys for elimination

• Hormones from the endocrine system

What does blood regulate?

• Body temperature

• pH levels

• Fluid volume

How does blood protect our body?

• Prevents blood loss

• Initiates clot formation

• Prevents infections from occuring

What are the 3 layers of centrifuged blood?

• Plasma

• Buffy Coat

• Erythrocytes

What are the relative amounts of plasma, buffy coat, and erythrocytes in a healthy body?

Plasma: 55%

Buffy coat: <1%

Erythrocytes: 45%

What does the plasma component of blood consist of?

• 90% water

• 8% plasma proteins

• 2% “other”

What does the buffy coat component of blood consist of?

• Leuokocytes (WBC)

• Platelets

Define hematocrit:

The percentage of blood volume that is RBC

What are the physical properties of blood?

• sticky, opaque fluid

• metallic taste

• red color

  • scarlet red when high amounts of O₂

  • dark red (“blue”) when low amounts of O₂

The pH of blood is…

7.35 - 7.45 (slightly basic!)

How many liters of blood circulate our body?

5 L

What function does water serve in plasma?

• Absorbs heat

• Acts as a solvent

What function does plasma proteins serve in plasma?

• contributes to osmotic prressure

• maintains water balance in blood and tissues

What components make up plasma proteins? Include the percentages.

• Albumin (60%)

• Globulins (36%)

• Fibrinogens (4%)

What is the function of Albumin?

To act as a main contributor to osmotic pressure

Describe and name the function of the alpha/beta globulins

Transport proteins produced by the liver; binds to lipids, metal ions, and fat-soluble vitamins

Describe and name the function of the gamma globulins

Antibodies that are produced by a special kind of WBC; released by plasma cells to identify and neutralize foreign invaders like bacteria, viruses, and parasites

What is the function of fibrinogen?

To form the fibrin threads of a blood clot and initiate clotting itself

What are the components of “Formed Elements”? Include the percentages.

• Buffy coat (<1%)

• Erythrocytes (45%)

List the structural characteristics of an erythrocyte

Biconcave shaped cell filled with hemoglobin and lined with the spectrin protein, enabling flexibility

Describe the chemical composition of hemoglobin

• 4 Polypeptide globin chains, each one containing a heme group

• 2 Alpha globin, 2 beta globin

• Each heme carries iron & binds to one O₂ molecule

Define hematopoiesis. Where does it occur?

Blood cell formation; occurs in the red bone marrow

Define erythropoiesis. How long does this process take?

Formation of red blood cells; around 15 days

List the steps of erythropoiesis

Hemocytoblast ^{(stem cell)} → Proerythroblast ^{(committed cell)} → Basophilic erythroblast → Polychromatic erythroblast → Orthochromatic erythroblast → Reticulocyte → Erythrocyte

What is the hormonal control mechanism of erythropoiesis? Describe it .

Erythropoietin (EPO); hormone produced by the kidneys that stimulates formation of RBC’s when O₂ levels are low.

What are the dietary needs required for erythropoiesis?

• amino acids

• lipids

• carbohydrates

• iron

• vitamin B₁₂ & B₆

• folic acid

Describe the process of destruction of erythrocytes

Macrophages engulf and destroy dying erythrocytes

• The core of iron in the heme is salvaged and bound to protein and stored for reuse

• Heme is degraded to bilirubin, turned to bile by the liver, and is excreted as feces

• The protein of the globin is metabolized or broken down into amino acids, then released into circulation

List the structural characteristics of leukocytes

Blood cell with nuclei and organelles; appears white due to their lack of hemoglobin, and is less numerous than RBC’s

List the 5 leukocytes in order from most abudant to least

Neutrophil

Lymphocyte

Monocyte

Eosinophil

Basophil

Describe the Neutrophil. What is its function(s)?

• Most abundant

• First responders to infection

• Bacterial slayers; phagocytizes bacteria

• Dies after eating the invaders and releases a chemical that continues the job

Describe the Lymphocyte. What is its function(s)?

• Plays a crucial role in immunity

• Closely associated with lymphoid tissues

• T-Cell, B-Cell, and Natural Killer (NK) cells

Describe the Monocyte. What is its function(s)?

• Largest of leukocytes

• Develops into macrophages in the tissues and are considered “big eaters”

• “Cleaning crew” that arrives after the invasion

Describe the Eosinophil. What is its function(s)?

• Responds to parasitic infections/worms that are too large to be phagocytized

• Gathers around parasitic prey and releases enzymes to digest/break it down

• Plays a role with allergic reactions and asthma

• Contributes to the tissue damage that occurs in many immune responses

Describe the Basophil. What is its function(s)?

• Releases histamine and intensifies inflammatory/allergic reactions

• Contains heparin, an anticoagulant

• Dilates blood vessels

• Attracts other WBC’s to the inflamed site

Describe the characteristics of a thrombocyte and describe its function(s)

• Fragments of megakaryocytes that contain granules and are roughly disc-shaped

  • Plugs damaged blood vessels and promotes blood clotting/coagulation

Define Hemostasis

A fast series of action to stop bleeding

What are the three steps that occur in hemostasis?

1. Vascular spasm

2. Platelet plug formation

3. Coagulation

Describe the vascular spasm step that occurs in hemostasis

The damaged blood vessels respond to injury by constricting, aka “vasoconstriction” — tells our body that there is an emergency, and a lot of chemicals are released by the endothelial cells and platelets.

Describe the platelet plug formation step that occurs in hemostasis

The chemicals released by the vascular spasm step summons platelets that form a temporary plug to seal the break in the wall. The blood connecting with the collagen fibers makes the platelets stick, causing for the release of even more chemicals and platelets

Describe the coagulation step that occurs in hemostasis

Fibrin forms a mesh so it can seal the leak and trap all the red blood cells and platelets, and makes the blood gel-like to seal the leak/break in the blood vessel.

List and describe the 3 substeps that occur in the coagulation step of hemostasis

1. Two pathways to prothrombin activator

   • Intrinsic pathway & extrinsic pathway

   • Activates prothrombin antigen

2. Common pathway to thrombin

   • Activates thrombin antigen

3. Common pathway to the fibrin mesh

   • Creates the fibrin mesh needed for clotting

Define Anemia

Condition in which the bloods oxygen carrying capacity is abnormally low

List the types of anemia

1. Thalassemias

2. Sickle cell

3. Pernicious

4. Iron-deficiency

5. Renal

6. Aplastic

What are the possible causes of anemia?

1. Sudden trauma to the body resulting in blood loss

2. Not enough RBC production

3. Too many RBC’s destroyed

What are some treatments that can be used for anemia?

Blood transfusions, transplants, or injections (EPO, Vitamins B₁₂…)

Describe thalassemias anemia

One of the globin chains is absent or faulty, and the RBCs are thin, delicate, and deficient in hemoglobin

Describe sickle cell anemia

Contains hemoglobin that are crescent shaped and pop prematurely; body is unable to catch up, causing painful blood clotting

Describe pernicious anemia

The small intestine does not absorb enough Vitamin B12; injections for the vitamin will be needed

Describe renal anemia

Kidneys are too damaged that they cannot produce enough EPO for RBC production; EPO injections will need to be administered

Describe aplastic anemia

Damage in the bone marrow, causing a low amount of blood cell production — bone marrow transplant will be needed

List the types of Polycythemia

Polycythemia vera & secondary polycythemia

What is polycythemia?

An abnormal excess production of RBCs

Describe polycythemia vera

Bone marrrow cancer leading to excess RBCs

Describe secondary polycythemia

A type of polycythemia that is caused by low oxygen levels or increased EPO production

Blood doping

Blood is drawn, held onto, and returned one the body replenishes the amount taken; causes temporary polycythemia and is illegally practiced by some athletes

Differentiate between the intrinsic vs extrinsic pathways

1. Intrinsic Pathway

   • Factors needed for clotting are within the blood

   • Triggered by negatively charged surfaces like activated platelets, collegen, or glass

   • More complicated & slower pathway

2. Extrincisc Pathway

   • Factors needed for clotting are present outside the blood

   • Triggered by exposing blood to a factor found on cells in tissues surround the blood vessel

   • Faster pathway

What role does blood clotting factors play in coagulation?

Acts as procoagulants, helping out with the formation of clots

What role does Ca⁺ play in coagulation?

Allows for the activation of certain clotting factors

What role does Vitamin K⁺ play in coagulation?

Required for the liver’s prodution of clotting factors; without it, the liver cannot produce them.

What role does caumadin or warfarin play in coagulation?

Blocks vitamin K⁺ synthesis, limiting/inhibitting the liver’s production of clotting factors

What role does heparin play in coagulation?

Speeds up the inactivation of thrombin to help prevent excessive blood clotting

Name the blood types

A, AB, B, O

Which blood type is the universal donor?

O-

Which blood type is the universal recipient?

AB+

What happens if mismatched blood is given in a transfusion?

The antibodies of the mismatched blood bind to the antigens on the RBC’s, causing them to hemolyze, or rupture

If incompatible blood types during pregnancy occur, what happens?

The mothers immune system attacks the baby’s blood cells with its antibodies

Which of the 5 leukocytes is biggest in size?

Monocyte

Which of the 5 leukocytes is smallest in size?

Lymphocyte

List the structural characteristics of a granulocyte

• Roughly spherical in shape

• Larger and much shorter-lived than erythrocytes

• Have lobed nuclei

• Contains membrane-bound granules

List the structural characteristics of an agranulocyte

• Roughly spherical in shape

• Have spherical/kidney-shaped nuclei

• Lacks visible cytoplasmic granules

What do T-Cells do?

Act directly against virus-infected cells and tumor cells

What do B-Cells do?

Give rise to plasma cells, which produce antibodies that are released into the blood