blood pressure

What is high blood pressure?
Blood pressure is really important for all of us. to know more about Blood pressure please imagine that arteries are pipes that carry blood from heart to the rest of the body. their main function is this. So if there is high blood pressure (also called hypertension) occurs when blood moves through the arteries at a higher pressure than normal. It depends on lots of different factors. And it is possible to cure this healty conditions.

blood plasma

A. Proteins
B. Nonprotein Nitrogenous Substances
C. Nutrients
D. Gases
E. Electrolytes

Blood Cell Formation :
A. Hemopoiesis: production of formed elements of the blood
B. Erythrocyte Production
C. Leukocyte Production
D. Platelet Production

Functions and Properties of Blood

Functions and Properties of Blood: Blood is a vital liquid for most of living things. Has very critical funtions
A. Role of blood in respiration, nutrition, waste elimination, thermoregulation, immune defense, acid-base balance, water balance, and internal communication.
B. Blood: connective tissue with plasma and formed elements.

Hemolymph

What is Hemolymph ?

It is a fluid more or less equivalent to the blood on a functional level in some invertebrates. It circulates freely throughout the body while men circulates in the blood vessels (veins, for example).

Diastole

What is Diastole ? Blood movements in your body and heart blood pumping functions are very critical. As you know when someone under heart attack, blood sending and receiving process stop and cause to dead of the person.

Diastole phase is the expansion of the heart when its cavities are filled with new blood, prior to eject blood (called systole). Is determined by measuring blood pressure in both diastolic pressure and systolic pressure. To do this, it uses an inflatable cuff called "sphygmomanometer".

Ketoacidosis

What is Ketoacidosis? its very important to know ketoacidosis when you study about blood histology and physiology.

Ketoacidosis is phase decompensation advanced type 1 diabetes leading to acidification of blood and the presence of derivatives of acetone in blood and urine. It causes fatigue, nausea, difficulty breathing and, without treatment coma.

Blood

Blood. One of the three important liquids of live. Blood , Water and sperm. Blood is basic important thing cause human and most of living things require blood.

Bloood fluid is circulating in the blood vessels. Blood is consisting of a liquid (plasma) in which bathe the figurative elements. The most important liquid organic which irrigates all organs, provides oxygen and nutrients and removes waste. Blood is composed of 55% plasma and 45% of cells, red blood cells, white cells and platelets.

Blood coagulation and blood cells

Platelets contain both substances which activate or inhibit blood clotting
Neutrophilic granulocytes and monocytes produce the tissue factor, the factor V, and phospholipids which all support blood clotting processes.

Regulation of hematopoiesis

There is big number regulatory substances, hematopoietic factors, which may influence almost all phases of hemaotpoiesis.
Hematopoietic factors are members cytokine family.
Hematopoietic factors are released from hematopoietic, stromal and other cells and can interact through specific receptors with different types of cells and change their functional activity.
Better understanding of hematopoiesis would improve treatment of hematological diseases

Main principles of hematopoiesis

All mature cells are originated from the pluripotent hematopoietic stem cells (HSCs)
Maturation of cells is going through several intermediate steps.
Capacity to differentiate is increasing and capacity to divide and sel-production is decreasing during maturation. Mature blood cells are not able to divide.
Usually only mature cells can reach blood
Hematopoiesis must and is very carefully regulated to hold stable number of cells in the blood

Hematopoiesis

In adult organism main place for hematopoiesis is red bone marrow, only some lymphocytes (T type) are coming from lymphatic . Before birth erythropoiesis is going in yolk sac (I trimester), liver, spleen, lymphatic tissue (II trimester) and red bone marrow (III trimester).

blood in vertabrates and invertabrates

•In vertebrates, the circulating fluid, or blood is kept within a closed circulating system, whereas hemolymph is the circulating fluid of animals with open circulatory system, for example insect.

•The coelomic fluid of some invertebrates also has a circulatorry role instead of blood.

•The function of blood.

•Respiratory pigments in blood.

•Transport of nutrients

•Circulate hormones

•Blood clotting

•İmmune reponses

•Phagocytosis of dead cells and foreign materials

•İmportant pH buffer system

•Constituents of blood can confer antifreeze properties.

•Heat exchange

•Blood volume is 6% in cephalopod mollusks, 3-16% in vertebrates, and 30% or more in arthropods.

•In animals having open circulatory system, the blood volume is only a fraction of the extracellular fluid volume but blood volume is only a fraction of the extracellular volume for animals with a closed circulatory system.

•Hematocrit value

Plasma volume, cell volume

The Roles of Platelets

1. Primary aggregation. Platelets in the damaged region attach to collagen revealed by the discontinuity in the vessel wall, forming a platelet plug.

2. Secondary aggregation. Platelets in the plug release the contents of their alpha and delta granules. This release of serotonin explains the higher concentration of serotonin in serum than in plasma. Scrotonin, a vasoconstrictor, restricts blood flow to the damaged area by causing contraction of vascular smooth muscle.

3. Blood coagulation. Platelets release fibrinogen in addition to that normally found in the plasma. The fibrinogen is converted by the clotting factor cascade into fibrin, which forms a dense fibrous mat to which more platelets and other blood cells attach, forming a clot and plugging the opening in the blood vessel wall.

D. Clot Retraction: The clot initially bulges into the vessel lumen, but later it contracts and condenses through the interactions of thromhosthenin and platelet actin, myosin, and ATP.

E. Clot Removal: As the vessel wall heals and the protection afforded by the clot is no longer needed, the clot is removed by the enzyme plasmin, Plasmin is formed by the action of plasminogen activators on the plasma proenzyme plasminogen Enzymes released by the lambda granules (lysosomes) of the platelets also aid in clot digestion

CLOT FORMATION - Blood clotting

A. The Clot and Serum: Clotted blood consists of 2 parts:

(1) the clot, or thrombus, which includes the formed elements and some of the proteins previously dissolved in the plasma, and

(2) the serum, a clear yellow liquid that is similar to plasma except that it lacks fibrinogen and contains more serotonin.

B. Clotting Factors: Clotting involves a cascade of molecular interactions among several plasma proteins and ions (clotting factors I-XIII). The cascade can be initiated by 2 converging pathways, each of which results in the conversion of fibrinogen to fibrin by the enzyme thrombin. In the intrinsic pathway, initiation of the cascade occurs when factor XII is activated by contact with collagen underlying the endothelium (indicating damage to the endothelial lining of a vessel). In the extrinsic pathway, cells in a damaged vessel wall or the surrounding tissue release an ill-defined clot-promoting substance termed thromboplastin (factor III), which com bines with blood calcium and factor VII to activate factor X, a plasma protein. Factor X is a point of convergence of the 2 pathways and, in its activated form, promotes the conversion of prothrombin (factor II) to thrombin. Both factor X and prothrombin are synthesized by the liver and require vitamin K as a cofactor in their synthesis. Thrombin enzymatically converts plasma fibrinogen (factor I, released into plasma by platelets and by the liver) into fibrin; this explains the lower concentration of fibrinogen in serum than in plasma. Other factors act as promoters and accelerators of the clotting process or help stabilize the fibrin once it has formed. An inherited abnormality in factor VIII (whose precise role in the clotting process is uncertain) results in the clotting disorder known as hemophilia.

Blood Platelets

Platelets, or thrombocytes, the smallest formed elements in the blood histology , are disklike cell fragments that vary in diameter from 2 to 5 um. In humans, they lack nuclei and originate by budding from large cells in the bone marrow called megakaryocytes. They range in number from 200,000 to 400,000 mm3 of blood and have a lifespan of about 8 days. In blood smears they appear in clumps. Each platelet has a peripheral hyalomere region that stains a faint blue and a dense central granulomere that contains a few mitochondria and glycogen granules and a variety of purple granules. Platelets have an important physical role in plugging wounds, and they contribute to the cascade of molecular interactions among the various clotting factors dissolved in the plasma blood histology

Basophils

Basophils are the least numerous of the circulating leukocytcs, constituting 1% of the white blood cells of healthy adults. Like other white blood cells, basophils may leave the circulation, but they are capable of only very limited ameboid movement and phagocytosis in the tissues. Extravascular basophils are found most often at sites of inflammation and may be the major cell type at sites of cutaneous basophil hypersensitivity. Despite structural and functional similarities between basophils and mast cells, these cells are not the same and are distinguishable on the basis of ultrastructure. blood histology

Eosinophils

Eosinophils constitute only 1-4% of the circulating leukocytes in healthy adults. They may leave the bloodstream by diapedesis, spread out, and move about in the connective tissues. They are capable of only limited phagocytosis, showing a preference for antigen antibody complexes. The number of circulating eosinophils typically increases during allergic reactions and in response to parasitic infections and rapidly decreases in response to treatment with exogenous corticosteroids in blood.

2. Granulocytes have segmented nuclei and are described as polymorphonuclear leukocytes (PMNLs). Depending on the cell type, the mature nucleus may have 2-7 lobes connected by thin strands of nucleoplasm. Granulocyte types are most easily distinguished by their size and staining properties and by the appearance (as seen by EM) of the abundant specific granules in their cytoplasm. These granules are all membrane-limited and bud off the Golgi complex.

In addition to a small Golgi complex, each granulocyte contains a few mitochondria and free ribosomes and sparse RER. a. Neutrophils are the most abundant leukocytes in the blood. They usually constitute 60-70% of the white blood cells, with a limited range of normal variation (50-75%). They are also found outside the bloodstream, especially in loose connective tissue. Neutrophils are the first line of cellular defense against the invasion of bacteria. Once they leave the bloodstream, they spread out, develop ameboid motility, and become active phagocytes. Unlike lymphocytes, neutrophils are all terminally differentiated cells and so are incapable of mitosis.

Agranulocytes - Monocytes

1. Agranulocytes have unsegmented nuclei and are described as mononuclear leukocytes. They lack specific granules, but may contain azurophilic granules (0.05-0.25 um in diameter). a. Lymphocytes constitute a diverse class of cells; they have similar morphologic characteristics but a variety of highly specific functions. They normally account for 20-25% of the white blood cells in adult blood, with a considerable range of normal variation (20-45%). They respond to invasion of the body by foreign substances and organisms and assist in their inactivation. Unlike other leukocytes, lymphocytes never become phagocytic. The 2 major functional classes of lymphocytes are T cells and B cells. Lymphocytes in the blood are predominantly (about 80%) T cells.


b. Monocytes are often confused with large lymphocytes. They are large and constitute only 3-8% of the white blood cells in healthy adults. Monocytes are found only in the blood, but they remain in circulation for less than a week before migrating through capillary walls to enter other tissues or to become incorporated in the lining of sinuses. Once outside the bloodstream, they become phagocytic and apparently do not recirculate. The mononuclear phagocyte system consists of monocyte-derived phagocytic cells distributed throughout the body. Examples include the Kupffer cells of the liver and some of the macrophages of connective tissues.

Leukocytes

Leukocytes, or white blood cells, are nucleated and are larger and less numerous (6000-10,000/Cl) than erythrocytes.
Leukocytes can be divided into 2 main groups, granulocytes and agranulocytes, according to their content of cytoplasmic granules. Each group can then be further divided on the basis of size, nuclear morphology, ratio of nuclear to cytoplasmic volume, and staining properties. Two classes of cytoplasmic granules occur in leukocytes: specific and azurophilic granules. Specific granules are found only in granulocytes; their staining properties (neutrophilic, eosinophilic, or basophilic) distinguish the 3 granulocyte types. Azurophilic granules occur in both agranulocytes and granulocytes.
Their content of lytic enzymes suggests that they function as lysosomes. Unlike the RBCs, all leukocytes can leave the capillaries by squeezing between endothelial cells, a process termed diapedesis, and enter the surrounding connective tissue in response to infection or inflamma tion. The types and levels of activity expressed by extravascular leukocytes depend upon the specific cell type

Formed elements of blood : hemoglobin

3. Hemoglobin. Each hemoglobin molecule consists of 4 polypeptide subunits, each of which includes an iron-containing heme group. Hemoglobin can bind reversibly to oxygen, forming oxyhemoglobin, and to carbon dioxide, forming carbaminobemoglobin. However, hemoglobin binds irreversibly to carbon monoxide, forming carboxyhemoglobin, which reduces the oxygen-carrying capacity of the blood. Hemoglobin (Hb) exists in a variety of forms, distinguishable on the basis of the amino acid sequence of their subunits. In humans, only 3 forms are considered normal in postnatal life: HbAI constitutes 97%, HbA2 2%, and HbF 1% of the hemoglobin of healthy adults. HbF makes up around 80% of the hemoglobin of newborns, however; this proportion gradually decreases until normal adult levels are reached at about 8 months of age. HbS is an abnormal form of HbA that is found in patients with sickle cell anemia; it differs by a single amino acid substitution in the beta chain (valine in HbS, glutamine in HbA). Unlike HbA, HbS becomes insoluble at low oxygen tensions and crystallizes into inflexible rods that deform the RBCs, giving them the characteristic sickle shape. When the rigid sickled cells pass through narrow capillaries, they cannot bend as normal RBCs do. They may become trapped, obstructing blood flow through the capillary, or rupture, decreasing the number of RBCs available for oxygen transport (anemia).

4. Plasmalemma and stroma. When placed in a hypotonic solution, RBCs swell and release their hemoglobin into the surrounding solution, a process termed hemolysis; they leave behind an empty shell, or red cell ghost, composed of the plasmalemma and the stroma.

FORMED ELEMENTS

A. Erythrocytes: Erythrocytes are also called red blood cells, or RBCs. They are the most abundant formed elements in the blood (4-6 x millions/uL). Because of their presence in most tissues and organs, erythrocytes are useful to histologists and pathologists in estimating the size of other tissue and organ components (through estimates of multiples or fractions of RBC diameter).
1. Normal structure and function. RBCs are structurally and functionally specialized to transport oxygen from the lungs to other tissues. Their cytoplasm contains the oxygen binding protein hemoglobin. Their small diameter (7-8 um) and biconcave shape (in humans) help to maximize their surface-to-volume ratio, facilitating oxygen exchange. Mature RBCs lack nuclei and cytoplasmic organelles, which they lose during differentiation. Because they lack mitochondria, the energy needed to maintain the hemoglobin in a functional state must be derived from anaerobic glycolysis. Because they lack ribosomes, the glycolytic enzymes and other important proteins cannot be renewed. Mature erythrocytes therefore have a limited lifespan (120 days) in the circulation before they are removed by macrophages in the spleen and bone marrow.2. Abnormalities a. Anisocytosis refers to the presence of a high percentage of RBCs with unusually great variations in size. Those larger than 9 µm in diameter are termed macrocytes, and those smaller than 6 um are termed microcytes. b. Nuclear fragments. In some disease states, nuclear fragments, or Howell-Joliy bodies, remain in otherwise mature RBCs. When these form circular filaments they are termed Cabot rings. c. Reticulocytes. Some RBCs recently released from the bone marrow contain a small amount of residual RER and ribosomes that can be precipitated into blue, netlike structures with the vital dye brilliant cresyl blue. When these reticulocytes constitute more than about 1% of the circulating RBCs, they indicate an increased demand for oxygen carrying capacity leg, from loss of RBCs due to hemorrhage or anemia, or to recent ascent to a higher altitude).

COMPOSITION OF PLASMA

A. Water: Plasma contains 90% water by volume.
B. Solutes: Plasma contains 10% solutes by volume. These solutes include plasma proteins and other organic compounds as well as inorganic salts.
1. Plasma proteins. Plasma contains a rich variety of soluble proteins, 7% by volume. Important examples include: a. Albumin. This is the most abundant plasma protein (3.5-5 g/dL of blood) and is mainly responsible for maintaining the osmotic pressure of blood. B. Globulins. Alpha, beta, and gamma globulins are globular proteins dissolved in the plasma. The gamma globulins include the antibodies, or immunoglobulins, synthesized by plasma cells. c. Fibrinogen. This protein is converted by blood-borne enzymes into fibrin during clot formation. Fibrinogen is synthesized and secreted by the liver. 2. Other organic compounds. Other organic molecules in plasma, include nutrients such as amino acids and glucose, vitamins, and a variety of regulatory peptides, steroid hormones, and lipids. 3. Inorganic salts. Inorganic salts in plasma, 0.9% by volume, include blood electrolytes such as sodium, potassium, and calcium salts.

GENERAL FEATURES OF THE BLOOD

A. Two Divisions: Humans have a total blood volume of about 5 L (depending on body size). Blood is divisible into 2 parts, the formed elements, which include the blood cells and platelets, and the plasma, or liquid phase, in which the formed elements are suspended and in which a variety of important proteins, hormones, and other substances are dissolved.
B. Basic Cell Types: There are 2 basic types of blood cells, the erythrocytes, or red blood cells, and the leukocytes, or white blood cells.
C. Clotting: Outside the blood vessels, blood undergoes a complex reaction called clot formation or coagulation, which plays an important role in repairing damaged vessels and preventing blood loss.
D, Hematocrit: When anticoagulants (heparin, citrate, etc) are added, blood samples can be separated in a centrifuge into 3 major fractions. The erythrocytes constitute the densest fraction and end up at the bottom of the tube. The hematocrit is the percentage of packed erythrocytes per unit volume of blood. In adults, normal hematocrit values vary from 35 to 50% and are sex dependent. Leukocytes are less dense and less numerous (about 1 % Of blood volume) and form a thin white or grayish layer over the erythrocytes. On top is a thin layer of platelets. The least dense is the clear layer of plasma, which constitutes 42 47% of the blood.
E. Differential Cell Count: Blood is also studied by spreading a drop on a slide to produce a single layer of cells (blood smear). The cells are stained, differentiated by type, and counted to reveal disease-related changes in their relative numbers. The smears are usually stained with Romanovsky-type dye mixtures containing eosin and methylene blue.
F. Staining Properties: All of the descriptions of the staining properties of blood cells refer to their appearance after staining with Romanovsky-type mixtures leg, Wright's or Giemsa). Blood cells and their components exhibit 3 major staining properties that allow the cell types to be distinguished:
1. Basophilia is an affinity for methylene blue. Basophilic structures stain purple to black. 3. Eosinophilia, or acidophilia, is an affinity for eosin. Eosinophilic structures stain salmon pink to orange.
4. Neutrophilia is an affinity for a complex of dyes (originally thought to be neutral) in the mixture. Neutrophilic structures stain salmon pink to lilac.