Overview of heart and blood

Bio 211

Blood

A connective tissue with a liquid matrix called plasma and three kinds of formed elements: erythrocytes, leukocytes, thrombocyte

Blood functions

Transportation, Defense, Maintenance of homeostasis, Body temperature, Body pH, Fluid Balance/Water content of cells

blood composition and volume

Measured by a Hematocrit (percent of erythrocyte in the blood) Consists of, from bottom to top, a layer of erythrocytes, a buffy coat, and a liquid portion known as plasma, Average values vary depending on gender and pathology

blood plasma composition

Water, Proteins, Electrolytes/Ions

albumins- protein blood plasma

Function to transport solutes and increase blood volume by osmosis

globulins- protein blood plasma

Alpha and beta function as transport proteins; gamma globulins function as antibodies

fibrinogen- protein blood plasma

Functions in blood clotting

How would liver disease affect the osmotic pressure of the blood?

Liver disease lowers the colloid osmotic pressure (oncotic pressure) of the blood. Because a damaged liver cannot make enough of the protein albumin, there are fewer proteins left in the blood vessels to pull and hold water. This drop in pressure causes fluid to leak out of the blood and into body tissues.

Sites of hematopoiesis in the embryo

Yolk sac, fetal liver, fetal spleen, lymphatic tissue, bone marrow

Sites of hematopoiesis post-birth through adulthood

Red bone marrow in most bones, including the diaphyses

Sites of hematopoiesis from adulthood

Epiphyses of long bones, sternum, skull bones, ribs, vertebrae, os coxae

hematopoiesis

the biological process by which the body creates new blood cells and platelets

Red blood cell function

Function to carry respiratory gases usually oxygen

red blood cell development

When they enter the bloodstream, they are immature and must develop. As they develop they eject their nucleus and other organelles (includin mitochondria which means they engage only in anerobic respiration

red blood cell proteins

Hemoglobin (carrying gases) and Spectrin (allows for bending)

hemoglobin

Also abbreviated Hg or Hgb, Hemoglobin is a 4-polypeptide protein, It consists of the 4

polypeptides of amino acids, 4 “heme groups” (an organic molecule called porphyrin), and 4

iron ions. The color of blood comes from the red pigment of the heme

anemia

A generic term for several forms of insufficient erythrocytes counts

polycythemia

Overproduction of erythrocytes (which can lead to a more viscous blood. The heart has to work

harder to deliver the same amount of oxygen)

low hemoglobin

A test called a “percent saturation” (or simply “percent sat”) indicates how many hemoglobin

binding sites are occupied by oxygen. 95-100% is normal. Lower values = not enough oxygen delivered to tissues

altitude hypoxemia

Decreased partial pressure of oxygen at high altitudes leads to less oxygen available to bind to the hemoglobin sites. Fatigue, breathlessness, and headache result. Causes EPO release from the kidneys in response

erythrocyte lifespan

120 days

erythrocyte rate of production

2 million every second

erythrocyte nutrients production

Glucose, lipids, amino acids, Vitamin B12, the B vitamin Folate, Trace amounts of Iron, Copper, and Zinc

destruction of erythrocytes

Occurs mostly in the spleen. The breakdown products include the Globin protein’s amino acids, which are recycled by the liver, the irons, which are recycled by the liver, and the heme molecule, which is repurposed by the liver

heme group breakdown

The liver converts the organic heme group to biliverdin (a green pigment responsible for some of the greenish tint to bruises as they develop). Biliverdin is converted into bilirubin (a yellow pigment

responsible for the yellowish tint to bruises as they heal, or jaundice, a liver disease). Bilirubin is used by the liver to make bile (a necessary substance for lipid digestion/metabolism). Bilirubin is then broken apart from the bile and converted to urobilinogen (responsible for the yellow color to urine), and then some to stercobilin (responsible for the brown color of feces)

anemias caused by bloodloss

Wounds, Hemorrhoids, Cancer, NSAIDS, Aspirin, Childbirth, Menstruation

anemia caused by faulty erythrocytes

Sickle Cell, Iron-deficiency, Vitamin deficiency, Megaloblastic, Pernicious, Celiac

Why are arteries thicker than veins?

Veins bring blood to the heart, which is a smaller muscle. Arteries bring blood to the rest of the body which needs more blood, and also has more urgency.

ANEMIAS CAUSED BY EXCESSIVE DESTRUCTION OF ERYTHROCYTES

Aplastic (Stem Cell Destruction), Thalassemia, Lead Exposure

charcterstics of leukocytes

Number: 5-9K/mm3, Function: Immunity/defense; guard against microorganisms

and foreign DNA; cellular “janitors” (clean up cellular debris), Shape – spherical with large nuclei

leukocytosis

An increased production of leukocytes due to infection or trauma

margination

Leukocytes will stick to blood vessel walls at the sites of injury

diapedisis

the movement of leukocytes to the sites of infection or injury

chemotaxis

the reason the leukocytes are drawn to those sites of injury. Pathogens leave chemical trails

that leukocytes “follow

granular leukocytes

Histologically, appear to have very grainy cytoplasm, Stain blueish (basic – basophils), reddish (acidic eosinophils), or lavender (neutral neutrophils), depending on the type Have multi-lobed nuclei

agranular leukocytes

Histologically, appear to have very few grains in the cytoplasm, Have large, rounded nuclei

Basophils- granular

Contain histamine granules that increase inflammation, Contain and release heparin, which inhibits

blood clotting Increase in number with allergies and parasitic infections

Eosinophils- granular

Produce anti-histamines to counteract inflammation Produce molecules that

are toxic to parasitic worms Increase with allergies, parasitic worm infestation, and some autoimmune disorders

neutrophils- granular

First responders to infection (produce our innate immunity), Phagocytize bacteria (contain lysozymes – enzymes that break down bacterial cell walls), Increase in number with generic bacterial

infections, burns, and even stress

lymphocytes types - agranular

NK (Natural Killer) Cells

• B-Cells

• T-Cells

NK/ natural killer lymphocytes

attack cells that do not express “self” on their plasma membranes (are seen by the body as being

foreign). They increase during cancer and when viruses infect cells. They provide non-specific immunity.

B-cells lymphocytes

produce antibodies; provide humoral (bodily fluids) immunity; retain memory of previous infections in

case of repeat infection; are produced in and mature in the red bone marrow.

T- cells lymphocytes

directly attack infected cells; produced in the bone marrow but mature in the thymus.

monocytes - agranular

Exist as monocytes when in the blood but become MACROPHAGES when they move to tissue to

take up residence. Phagocytize dead cells, cellular debris, large wastes, pathogens, dead

erythrocytes, damaged cells

differential count

A differential count determines both the number and types of leukocytes in a sample of blood. Gives an indication of potential issues with elevated or reduced numbers as a whole, and of certain types of

cells

leukocytes lifespan

few hours to a few days

leukocytes production

Most lymphocytes can undergo mitosis which leaves ‘memory’ to certain foreign pathogens Production occurs in response to leukocyte hematopoietic factors; monocytes take the myeloid line

and lymphocytes take the lymphoid line

leukemia

leukocyte disorder cancer that produces non-functional cells

lymphoma

leukocyte disorder that is a cancer of lymph organs that assist with immunity

leukocytosis

leukocyte disorder that has a high count of non-functional leukocytes

leukopenia

leukocyte disorder that has insufficient numbers of leukocytes

thrombocytes/ platelets

Their name is a misnomer; they never were cells. Number: 350K-500K. Develop via the myeloid

stem cell line as broken fragments of megakaryocytes. Function to help stop blood loss in damaged vessels and produce factors that promote tissue healing. 1/3rd of them are stored in the spleen “if needed”

thrombocytosis

platelet disorder with too high numbers of platelets; leads to excessive blood clotting

thrombocytopenia

platelet disorder that has too low numbers of platelets; leads to excessive bleeding and inability to

clot

hemostasis

the multi-step process of stopping blood loss from damaged vessels

- Occurs in three stages:

• Vascular spasm

• Platelet Plug Formation

• Coagulation

vascular spasm

vasoconstriction limits blood flow to the damaged area

platelet plug formation

The platelets begin to stick to the damaged endothelial wall of the broken vessel. They form a temporary dam, limiting the blood leaking through the wall of the vessel

coagulation

This third step involves a series of chemical reactions involving “clotting factors”. Clotting factors are 12 different molecules that react together to ultimately produce the insoluble protein ‘fibrin’. Fibrin forms the permanent clot to seal the vessel wall so the healing process can begin. Occurs via an intrinsic (internal vascular damage) or an extrinsic (external vascular damage) pathway until

these join to form a single pathway

clot removal

Fibrinolysis: the gradual degradation of the clot. Plasma Anticoagulants: those substances naturally

found in plasma that assist with fibrinolysis. Thrombolytic Agents: administered agents that

break up clots. Anticoagulants: prolong the time it takes for coagulation to occur. Antithrombins: prevent formation of thrombin

thrombophillia

platelets tend to spontaneously stick to each other; can be caused by Lupus, heparin sensitivity, polycythemia, sickle cell disease, pregnancy, obesity

causes of clotting

• Vitamin K deficiency

• Calcium deficiency

• Hormones

• Stagnant body position

• Smoking

blood antigens

Antigens are proteins embedded in the plasma membrane of erythrocytes. Because there are other

antigens attached to cells, these particular ones are called “blood” antigens. The most common are

named A and B (forming the ABO System), and Rh (or D) (forming the Rh System

blood antibodies

Antibodies are proteins found in the plasma of the blood (*not* attached to the cells). Antibodies are generally referred to as “Anti-A Antibody” or “Anti-B Antibody” so as not to confuse them with “A

Antigen” or “B Antigen”. While Anti-Rh Antibodies can be made they are normally not present in blood; Under special situations, they can appear

Rh blood type

A different type of antigen may be present on erythrocytes, named the Rh antigen. It is inherited differently from the A and B antigens Therefore it is standard practice to state a letter (A, B, AB or O) and a symbol (positive or negative) when giving a blood type, to give a full type.

Rh antibodies

Unlike Anti-A and Anti-B Antibodies, which are present from birth, even with no exposure to foreign blood, the Rh negative body does not contain antibodies to the Rh antigen unless it has been exposed to Rh positive blood. These might happen in transfusions with Rh positive blood or when an Rh negative mother bears an Rh positive child.