UAlberta Physl 210A Blood

Whole Blood

Mixture of plasma and formed elements. Can be separated with centrifugation.

Blood Layers

Top: Plamsa; 55%,
Middle: Buffy Coat (WBC and platelets); <1%,
Bottom: RBC; 45%.

Hematocrit

Percentage of blood volume occupied by packed red blood cells.

Hematocrit Value for Males

47 +/- 5%.

Polycythemia

Condition associated with high numbers of RBC. Can be an adaptive development in areas with low oxygen. Makes blood more viscous which puts a strain on the heart.

Fluid Compartments of the Body

Intracellular and extracellular.

Intracellular Fluid ICF

Fluid within cells.

Extracellular Fluid ECF

Fluid outside and between cells. Made of plasma and interstitial fluid.

Interstitial Fluid IF

Fluid outside vessels and in between other cells.

Plasma

Liquid portion of blood.

Plasma Components

Water, electrolytes, organic molecules, trace elements, and gases.

Plasma Proteins

Albumin, globulins, fibrinogen, and transferrin. They are made in the liver.

Plasma Protein Function

Distribution of body water, buffering, transport, defence, hemostasis.

Albumin

Plasma proteins made in the liver that contribute to the colloid osmotic pressure of plasma and transports substances in the plasma.

Globulins

Plasma proteins made in the liver and lymphoid tissues that act as clotting factors, enzymes, and antibodies and carry various substances in plasma.

Transferrin

Plasma protein made in the liver that transports iron.

Fibrinogen

Plasma protein made in the liver and other tissues that forms fibrin threads for clotting.

Serum

Blood plasma that has been removed of clotting factors.

Red Blood Cells RBC

Also called erythrocytes. They transport oxygen and carbon dioxide. 4.2-5.4x10^6/ul blood in females and 4.7-6.1x10^6/ul blood in males.

White Blood Cells WBC

Also called leukocytes. They help with immune function. 4.5-10x10^3/ul blood. Many different types.

Platelets

Also called thrombocytes. They help to prevent bleeding. 1.5-4x10^5/ul blood.

Polymorphonuclear Granulocytes

Cells that have differing nuclear structures and granular structures in their cytoplasm.

Blood Cell Characterization

How granular structures of granulocytes are stained by hematoxylin and eosin determines ___.

Types of WBC

Polymorphonuclear granulocytes, monocytes, and lymphocytes.

Types of Polymorphonuclear Granulocytes

Neutrophils, eosinophils, and basophils.

Neutrophils

Type of polymorphonuclear granulocytes that have granular structures that are not attracted to acidic or basic dye. They have highly segments nuclei and can engulf particulate matter through phagocytosis. Make up 40-60% of WBC.

Eiosinophils

Type of polymorphonuclear granulocytes that have granular structures that are attracted to the acidic eosin dye and are turned pink. They have a single, segments nucleus (bilobed) and are involved in parasitic defence. Make up 1-4% of WBC.

Basophils

Type of polymorphonuclear granulocytes that have granular structures that are attracted to the basic hematoxylin dye and turn purple. They have a 2 or 3 lobed nucleus and are involved in inflammation. Make up <1% of WBC.

Monocytes

Type of very large WBC with a single, large nucleus. They provide immune defence through phagocytosis. Make up 2-8% of WBC.

Types of Lymphocytes

T cells and B cells.

T-Cells

Type of lymphocyte that provides us with cellular immunity. Leave the bone marrow and move to the thymus gland to complete development before entering the blood stream.

B-Cells

Type of lymphocyte that produces antibodies and provides us with humoral immunity. Remain in the bone marrow during development before entering the blood stream.

Hematopoiesis

The process of blood-cell formation. At birth, it's in the yolk sac and spleen/liver, after birth it's in the bone marrow.

Multipotent Hematopoietic Stem Cell

The undifferentiated cell that is capable of forming any types of blood cell.

Process of Platelet Formation

Multipotent hematopoietic stem cell->myloid stem cell->megakaryocyte->platelets.

Process of Lymphocyte Formation

Multipotent hematopoietic stem cell->T-lymphocyte precursor->T-lymphocyte (thymus)->lymphocyte.

Process of Erythrocytes, Monocytes, and Polymorphonuclear Granulocytes

Multipotent hematopoietic stem cell->myloid stem cell->specific cell.

Cytokines

Small hormone-like proteins, aka hematopoietins, that act as growth factors. Can work alone or with other cytokines to regulate hematopoiesis.

Types of Cytokines

Erythropoietin and thrombopoietin.

Erythropoietin EPO

Cytokine that helps with the development of erythrocytes (RBC). Mostly made in the kidneys but also in connective tissue.

Thrombopoietin TPO

Cytokine that helps with the development of thrombocytes (platelets).

Factors That Help in RBC Production

Iron (most important), folic acid, intrinsic factor to release B12 from food, and cytokines.

RBC Characteristics

Red in colour due to hemoglobin, biconcave to allow for a greater SA and easy diffusion, do not contain a nucleus, live ~120 days. 7-8um in diameter, 2-3um in thickness, and we have ~5x10^6/ul of blood.

Hemoglobin Hb

Made of a non-protein part called heme and a protein part called globin. Usually found as hemoglobin A in humans and transports oxygen through the body. It actually has a higher affinity to CO which is what makes inhalation more deadly.

Hemoglobin Structure

4 Globin chains (2 alpha, 2 beta), with a heme group in the middle containing a bivalent iron. 1 molecule has 4 globin chains, 4 heme groups, 4 ferrous iron molecules.

What % of Oxygen Transport Happens Through the Binding of Oxygen to Hemoglobin?

98-99%

Oxyhemoglobin

Relaxed binding structure where the globin chains have a confirmation that make is easy for oxygen to bind to the 4 sites. As oxygen bind, the structure becomes more relaxed and oxygen affinity increases.

Deoxyhemoglobin

Once all sites are occupied, hemoglobin is carried by RBC to different tissues. Once the O2 is delivered the structure becomes tighter and stops the hemoglobin from binding to anything else after the O2 is released.

When is EPO Released?

During periods of low oxygenation like with low blood volume, anemia, low hemoglobin, poor blood flow, and pulmonary disease.

Response to Low Blood Oxygenation

Decrease in tissue oxygenation->kidney stimulation to release EPO->stimulates hematopoietic stem cells in bone marrow->increases production of RBC by bone marrow->increases oxygen-carrying capacity of blood flow->increase tissue oxygenation.

Hypoxia

Low oxygen concentration in the blood.

Iron Uptake and Reccirculation

1. From food, iron is absorbed into the blood vessels where it can either be stored in the liver when it is bound to ferratin, lost, or travel through the blood when it is bound to transferrin.
2. Transferrin allows the iron to be taken into the bone marrow where new erythrocytes are formed, and the iron is incorporated in the hemoglobin of RBC.
3. Once RBC circulate for about 120 days, the old erythrocytes are removed by the spleen or the kidneys.
4. Once the cells are broken down, iron is released from the heme group and put back into the blood stream to be reused.

Iron Forms in the Body

50% bound to hemoglobin, 25% bound to transferrin, 25% bound to other tissues.

Iron Recycling from RBC

Old/damaged RBC are taken up by macrophages in the spleen my phagocytosis, hemoglobin is broken down into heme and globin; heme is broken down into iron and biliverdin (iron is absorbed into blood for erythropoiesis or stored in the spleen or liver bound to ferratin, and biliverdin is converted to bilirubin which is secreted into bile and enters the small intestine) and globin is broken down into its amino acids.

Heme

Iron-based, pigment part of hemoglobin. Made of iron and biliverdin.

Globin

Protein portion of hemoglobin.

Biliverdin

Green bile pigment produced from hemoglobin breakdown. Pigment responsible for the green colour of bruises.

Bilirubin

Orange pigment produced from the breakdown of biliverdin.

B12

Required for the normal production of RBC, obtained from the diet, and absorbed in the ileum tract with the help of intrinsic factor (forms a complex).

Pernicious Anemia

Lack of mature erythrocytes caused by inability to absorb vitamin B12 into the bloodstream.

Anemia

Any decreased oxygen carrying capacity of the blood due to a deficiency of RBC and/or hemoglobin.

Causes of Anemia

Decreased RBC production in the bone marrow, increased destruction of RBC in the body, increased blood loss, abnormal hemoglobin production.

Hemolytic Anemia

Reduction in RBC due to excessive destruction.

Hemmohagic Anemia

Reduction in RBC due to excessive bleeding or blood loss.

Aplastic Anemia

Failure of blood cell production in the bone marrow due to aplasticity.

Specific Factors Resulting in Anemia

Lack of iron is the most common dietary cause, lack of intrinsic factor or vit B12, damage of bone marrow due to drugs or radiation leading to aplastic anemia, chronic kidney disease causing a reduced production of EPO, increased breakdown due to abnormal shape of RBC or immune reactions during transfusion, increased blood loss due to injury, bleeding ulcers, or heavy menstruation, or abnormal hemoglobin structure.

Sickle Cell Disease (Anemia, HbS)

A genetic disease in which the red blood cells are misshapen, hard, and not flexible due to one incorrect amino acid in the blood protein hemoglobin (point/gene mutation). When the cells become misshapen, they clump together and prevent blood from supplying oxygen to the tissues and are damaged as they pass thorugh. Homozygotes have all misshapen cells while heterozygotes have a few. More common in places with Malaria.

Immunity

The body's defence system. Deals with the processes that help the interior to defend from anything that is foreign and protects us from internal damage signals.

Types of Immunity

Adaptive/acquired and innate.

Humoral Immunity

Type of adaptive immunity. It develops over time, as we are exposed to foreign substances to create highly specific responses. WBC are involved. Cannot be generated without using innate immunity. Major defence against bacteria.

Cellular Immunity

Type of adaptive immunity but does not involve antibodies. It involves the activation of phagocytes, T-cells (cytotoxic, helper, and memory), and the release of various cytokines. Protection against viral infections, cancer, and transplanted organs.

Innate Immunity

Immunity we are born with. It produced non-specific responses. Physical and chemical defences are involved like skin, saliva, tears, mucus, enzymes, and gastric acids. After these are used, RBC are used.

Features of Humoral Immunity

Specific, has "memory", functions slowly (days-weeks), involves lymphocytes (B- and T-cells), antibodies, and cytotoxic molecules.

Features of Innate Immunity

Non-specific, does not have "memory", functions quickly (sec/min/hr), involves phagocytes (neutrophils and macrophages) and complement system.

Appropriate Immune Responses

Defence against foreign invaders, removal of our own old damaged or abnormal cells, identification and destruction of abnormal or mutant cells.

Inappropriate Immune Responses

Exaggerated responses to harmless substances like with allergies and autoimmune reactions or immune system attacking our own healthy cells.

Inflammation

Nonspecific immune response to injury. Something becomes inflamed but the main goal is healing and resolution.

Fibrosis

Occurs when the healing process begins, fibrous tissue in the affected area and scar tissue begins to form.

Nickname for Inflammation

"The Secret Killer"

Cardinal Signs of Inflammation

-Redness caused by increased blood flow due to the release of histamine.
-Swelling/Edema caused by increased blood flow due to the release of histamine.
-Heat caused by increased blood flow due to the release of histamine.
-Pain caused by pressure on and sensitivity of nerve endings caused by the release of bradykinin and prostaglandin.

Changes in Vasculature Following Injury

Release of mediators (histamine) which causes vasodilation to increase blood flow which causes redness and heat. Histamine also causes vessels to become more leaky and permeable, allowing proteins and fluid to move to the extracellular space which causes swelling.

Mast Cells

Cells that release chemicals (such as histamine) that promote inflammation. Look similar to basophils.

Cellular and Vascular Events of Acute Inflammation

Cellular: Resident macrophages entrap and kill pathogens and release chemical signals and other cytokines, increased movement of WBC like neutrophils and monocytes to the infected area. Ultimate outcome is to cause or bring about phagocytosis and destruction of foreign agent.
Vascular: Histamine release, blood vessel dilation and leakiness, accumulation of protein and fluid in the extracellular spaces, and additional inflammatory mediators are released with time (bradykinin, prostaglandins, complement proteins).

Acute Inflammation

Short term response to injury

Primary Goal of WBC During Inflammation

Accumulate in the affected area and kill the foreign agent.

How to WBC Accumulate and Kill the Foreign Agent?

1. Margination of WBC: WBC move to the cell wall of endothelial cells in capillaries.
2. Tethering and rolling: WBC use their expressed proteins to bind to proteins on the endothelial cells (tethering). This binding slows the WBC down and they begin rolling.
3. WBC and endothelial cell activation: Cells express more surface proteins and change shape.
4. Arrest/firm attachment of WBC to endothelial cells: Activated WBC firmly attach to endothelial cells.
5. Emigration/diapedesis: Cells move out from within the vessels to the interstitial space by squeezing through the adjacent endothelial cells.
6. Chemotaxis of WBC: Once they are in the tissue space, they move to the site of inflammation with the help of chemical factors.
7. Recognition of foreigners: WBC find and identify foreign substances.
8. Phagocytosis of foreigners: WBC engulf foreigners and kill them.

Chemotaxis

Ability of WBC to move against a concentration gradient in response to chemical factors. Factors are called chemotactic or chemoattractin factors.

Chemotactic Factors

Factors that cause chemotaxis. Includes activated compliment proteins, cytokines (chemokines), bacterial breakdown products, and arachidonic acid metabolites from damaged membranes.

Phagocytes

A type of white blood cell that ingests invading microbes. Includes neutrophils and macrophages.

Phagocytosis Sequence

1. Recognition of foreign agent by using pattern recognition receptors (PRR).
2. Attach to the foreign body by opsonization.
3. Internalization through cytoplasmic processes.
4. Destruction of the foreign agent within the cell.

Pattern Recognition Receptors PRR

Toll-like receptors on the surface of macrophages and neutrophils that help in the recognition of common patterns given by foreign agents. They cannot specifically identify the foreign agent.

Opsinization

The processes of speeding up phagocytosis through the addition of opsins to the surface of the non-self agent.

Opsin

Molecules added to the surface of non-self agents that act as tags for receptors on the host body to speed up the process of phagocytosis. They may be antibodies or compliment-type proteins.

Types of Killing by Neutrophils

Oxygen-dependent, oxygen-independent, suicidal.

Oxygen-Dependent Killing

Corrosive free radicals are produced to destroy the foreign body. Happens inside the neutrophils where oxygen is used to create free radicals that act like bleach. Neutrophils in the area require a lot of oxygen which creates an oxidative burst.

Oxygen-Independent Killing

Enzymatic killing using lysozymes, lactoferrin, and defensins. Neutrophils are equipped with certain proteins that are bactericidal and dissolve the foreign body.

Bacteriocidal Enzymes

Lysozyme: action inside the cell to degrade the entire bacteria,
Lactoferrin: action in extracellular space binds to iron and reduces iron in the environment so bacteria cannot grow,
Defensins: action outside of the cell, they drill holes in the bacteria.

Suicidal Killing

Neutrophils die as they kill the foreign body outside themselves using NETs (Neutrophil extracellular traps). Neutrophils extend out and break bacterial membrane releasing enzymes and trapping the bacteria to kill it.

Neutrophilic Killing

Destructive, and it does not discriminate against good and bad cells. Products like lysosomal enzymes and oxygen-derived active metabolites are released during phagocytosis.

Compliment Proteins

Inactive proteins found in plasma that are involved in innate defence. Once they are signalled, the cascade of activation reactions amplifies the signal.