SEMINAR IN MICROANATOMY AND HISTOLOGY OF BLOOD.

MICROANATOMY OF BLOOD

1. MICROANATOMY OF BLOOD Presented By: Balogun Ayomide Emmanuel Matric No: BMS/20/21/0147 Lecturer-in-charge: Dr O.J. Otunlana Course Code: ANA 405 Course Title: Seminar in Microanatomy

2. Table of content Introduction Properties Composition Blood cells; RBC, WBC, Platelet Plasma: Serum Complete blood count (CBC) Where do blood cells come from? Blood disorders: Anemia as a case study. References

3. INTRODUCTION Blood is a connective tissue in fluid form. It is widely regarded as the fluid of life because it carries oxygen from lungs to all parts of the body and carbon dioxide from all parts of the body to the lungs. It is also known as the fluid of growth because it carries nutritive substances from the digestive system and hormones from endocrine glands to all the tissues. The blood is also called the fluid of health because it protects the body against diseases and gets rid of the waste products and unwanted substances by transporting them to the excretory organs like kidney.

4. PROPERTIES Colour: Blood is red in colour . Arterial blood is scarlet red because it contains more oxygen and venous blood is purple red because of more carbon dioxide. Fluidity: Blood is a liquid connective tissue, allowing it to flow smoothly through the circulatory system reaching every part of the body Volume: Average volume of blood in normal adult is 5 L. In a newborn baby, the volume is 450 ml. It increases during growth and reaches 5 L at the time of puberty. In females, it is slightly less and is about 4.5 L. It is about 8% of the body weight in a normal young adult, weighing about 70 kg.

5. Viscosity: Blood has a certain thickness or viscosity, which is crucial for maintaining proper blood flow. It is five times more viscous than water and it is mainly due to red blood cells and plasma proteins. Reaction and pH: Blood is slightly alkaline and its pH in normal conditions is 7.4

6. COMPOSITION Blood contains the blood cells which are called formed elements and the liquid portion known as plasma . BLOOD CELLS: Red blood cells or erythrocytes : They are non-nucleated formed elements in the blood. Their red colour is due to the presence of the colouring pigment called haemoglobin which also helps carry oxygen from the lungs to the rest of the body and then returns carbon dioxide from the body to the lungs so it can be exhaled. RBCs play a vital role in transport of respiratory gases. The function of the erythrocytes is the transport of oxygen from the lung to the tissue by bonding oxygen to the iron-containing heme group of the hemoglobin. Erythrocytes are round and have a biconcave shape as they have no nucleus. An erythrocyte has a diameter of 8 to 10 µm. A healthy adult has about 5 million/µl erythrocytes. Also, the blood group antigens are expressed on the surface membrane of the erythrocytes . They are also the most abundant cel l in the blood, accounting for about 40 to 45 per cent of its volume. Their production is controlled by Erythropoietin , a hormone produced primarily by the kidneys. RBCs starts as immature cells in the bone marrow and after approximately seven days of maturation are released into the bloodstream. The red blood cell survives on average only 120 days. The percentage of whole blood volume that is made up of RBC is called the hematocrit and is a common measure of red blood cell levels.

7. Erythrocytes (Histological slide)

8. White blood cells or leucocytes : Unlike mature erythrocytes, leucocytes have a nucleus. Different types of leucocytes can be found in the blood: Neutrophil  granulocytes (banded and segmented) Eosinophil  granulocytes Basophilic granulocytes Lymphocytes Monocytes The normal concentration of leucocytes ranges from 4,000 to 10,000 per µl, depending on age and health status. Both leucocytes and erythrocytes are descendants of pluripotent hematopoietic stem cells from the  bone marrow.

9. The primary function of leucocytes is the immune defense. Especially lymphocytes (25 to 40% of leucocytes) are responsible for the adaptive immune response, the specific defense from pathogenic germs. The B lymphocytes produce antibodies which are proteins that specifically target bacteria,viruses , and other foreign materials. W hereas  T lymphocytes mediate the antibody production and the direct cellular immune response. Monocytes  (4 to 8% of leucocytes) have the task of phagocytosis (e.g. removing foreign materials, bacteria etc.) by producing extremely reactive free oxygen radicals which are capable of penetrating and destroying bacteria wall. Monocytes may differentiate into fixed macrophages ( histiocytes ) in  connective tissue or into free macrophages.

10. Neutrophil

11. Platelets ( thrombocytes ): Unlike red and white blood cells, platelets are not actually cells but rather small fragments of cells. Platelets help the blood clotting process (or coagulation) by gathering at the site of an injury, sticking to the lining of the injured blood vessel, and forming a platform on which blood coagulation can occur. This results in the formation of a fibrin clot, which covers the wound and prevents blood from leaking out. Fibrin also forms the initial scaffolding upon which new tissue forms, thus promoting healing. A higher than normal number of platelets can cause unnecessary clotting, which can lead to strokes and heart attacks; however, thanks to advances made in  antiplatelet therapies , there are treatments available to help prevent these potentially fatal events. Conversely, lower than normal counts can lead to extensive bleeding.

12. Complete blood count (CBC) A complete blood count ( CBC) test gives your doctor important information about the types and numbers of cells in your blood, especially the red blood cells and their percentage ( hematocrit ) or protein content (hemoglobin), white blood cells, and platelets. The results of a CBC may diagnose conditions like  anemia , infection, and other disorders. The platelet count and plasma clotting tests ( prothombin time, partial thromboplastin time, and thrombin time) may be used to evaluate bleeding and clotting disorders .

13. Where do blood cells come from? Blood cells develop from hematopoietic stem cells and are formed in the bone marrow through the highly regulated process of hematopoiesis . Hematopoietic stem cells are capable of transforming into red blood cells, white blood cells, and platelets. These stem cells can be found circulating in the blood and bone marrow in people of all ages, as well as in the umbilical cords of newborn babies. Stem cells from all three sources may be used to treat a variety of diseases, including leukemia, lymphoma, bone marrow failure, and various immune disorders.  

14. BLOOD PLASMA Blood plasma  is a light amber-colored liquid component of  blood in which blood cells are absent, but which contains  proteins and other constituents of whole blood in suspension. It makes up about 55% of the body's total blood volume. It is the intravascular part of extracellular fluid (all body fluid outside cells). It is mostly water (up to 95% by volume), and contains important dissolved proteins (6–8%; e.g.,  serum albumins , globulins, and fibrinogen ), glucose , clotting factors, electrolytes (Na + , Ca 2+ , Mg 2+ , HCO 3 − ,  Cl − , etc.), hormones, carbon dioxide (plasma being the main medium for excretory product transportation), and  oxygen. It plays a vital role in an intravascular osmotic effect that keeps electrolyte concentration balanced and protects the body from infection and other blood-related disorders .

15. A unit of fresh donated plasma

16. Plasma Proteins Serum albumins are the most common plasma proteins, and they are responsible for maintaining the osmotic pressure of the blood. Without albumins, the consistency of blood would be closer to that of water. The increased viscosity of blood prevents fluid from entering the bloodstream from outside the capillaries. Albumins are produced in the liver, assuming the absence of a hepatocellular deficiency . Globulins The second most common type of protein in the blood plasma are globulins. Important globulins include immunoglobins which are important for the immune system and transport hormones and other compounds around the body. There are three main types of globulins. Alpha-1 and Alpha-2 globulins are formed in the liver and play an important role in mineral transport and the inhibition of blood coagulation. An example of beta globulin found in blood plasma includes low-density lipoproteins (LDL) which are responsible for transporting fat to the cells for steroid and membrane synthesis. Gamma globulin, better known as immunoglobulins , are produced by plasma B cells, and provides the human body with a defense system against invading pathogens and other immune diseases . Fibrinogen Fibrinogen proteins make up most of the remaining proteins in the blood. Fibrinogens are responsible for clotting blood to help prevent blood loss .

17. Blood Serum Serum is the fluid and solvent component of  blood which does not play a role in  clotting. It may be defined as blood plasma without the clotting factors, or as blood with all cells and clotting factors removed. Serum contains all proteins except clotting factors (involved in blood clotting), including all electrolytes, antibodies, antigens, hormones; and any exogenous substances (e.g., drugs, microorganisms). Serum also does not contain all the formed elements of blood, which include blood cells (white blood cells ( leucocytes ), red blood cells (erythrocytes), lymphocytes) and platelets . The study of serum is serology. Serum is used in numerous diagnostic tests as well as blood typing. Measuring the concentration of various molecules can be useful for many applications, such as determining the therapeutic index of a drug candidate in a clinical trial . To obtain serum, a blood sample is allowed to clot (coagulation). The sample is then centrifuged to remove the clot and blood cells, and the resulting liquid supernatant is serum .

18. Preparation of serum cups for a lipids panel designed to test cholesterol levels in a patient's blood

19. Blood disorders Anemia: Anemia is the most common blood disorder, and according to the National Heart, Lung, and Blood Institute, it affects more than 3 million Americans.  The role of red blood cells in anemia: Red blood cells carry hemoglobin, an iron-rich protein that attaches to oxygen in the lungs and carries it to tissues throughout the body. Anemia occurs when you do not have enough red blood cells or when your red blood cells do not function properly. It is diagnosed when a blood test shows a hemoglobin value of less than 13.5 gm/dl in a man or less than 12.0 gm/dl in a woman. Normal values for children vary with age.

20. When you have anemia, your body lacks oxygen, so you may experience one or more of the following symptoms: Weakness Shortness of breath Dizziness Fast or irregular heartbeat Pounding or "whooshing" in your ears Headache Cold hands or feet Pale or yellow skin Chest pain

21. Common types of Anemia Iron-deficiency anemia is the most common type of anemia. It happens when you do not have enough iron in your body. Iron deficiency is usually due to blood loss but may occasionally be due to poor absorption of iron. Pregnancy and childbirth consume a great deal of iron and thus can result in pregnancy-related anemia . People who have had gastric bypass surgery for weight loss or other reasons may also be iron deficient due to poor absorption. Vitamin-deficiency anemia  may result from low levels of vitamin B12 or folate (folic acid), usually due to poor dietary intake. Pernicious anemia is a condition in which vitamin B12 cannot be absorbed in the gastrointestinal tract.

22. Aplastic anemia   is a rare bone marrow failure disorder in which the bone marrow stops making enough blood cells (red blood cells, white blood cells, and platelets). This occurs as a result of destruction or deficiency of blood-forming stem cells in your bone marrow, in particular when the body’s own immune system attacks the stem cells. However, the few blood cells the marrow does make are normal. Viral infections, ionizing radiation, and exposure to toxic chemicals or drugs can also result in aplastic anemia. Hemolytic anemia    occurs when red blood cells are broken up in the bloodstream or in the spleen. Hemolytic anemia may be due to mechanical causes (leaky heart valves or aneurysms), infections, autoimmune disorders, or congenital abnormalities in the red blood cell. Inherited abnormalities may affect the hemoglobin or the red blood cell structure or function. Examples of inherited hemolytic anemias include some types of thalassemia and low levels of enzymes such as glucose-6 phosphate dehydrogenase deficiency. The treatment will depend on the cause.

23. Sickle cell anemia  is an inherited hemolytic anemia in which the hemoglobin protein is abnormal, causing the red blood cells to be rigid and clog the circulation because they are unable to flow through small blood vessels. Anemia caused by other diseases    - Some diseases can affect the body's ability to make red blood cells. For example, some patients with kidney disease develop anemia because the kidneys are not making enough of the hormone erythropoietin to signal the bone marrow to make new or more red blood cells. Chemotherapy used to treat various cancers often impairs the body's ability to make new red blood cells, and anemia often results from this treatment.

24. Sickle cell Anemia

25. How is Anemia treated? The treatment for anemia depends on what causes it. Iron-deficiency anemia is almost always due to blood loss. If you have iron-deficiency anemia, your doctor may order tests to determine if you are losing blood from your stomach or bowels. Other nutritional anemias , such as folate or B-12 deficiency, may result from poor diet or from an inability to absorb vitamins in the gastrointestinal tract. Treatment varies from changing your diet to taking dietary supplements. If your anemia is due to a chronic disease, treatment of the underlying disease will often improve the anemia. Under some circumstances, such as chronic kidney disease, your doctor may prescribe medication such as erythropoietin injections to stimulate your bone marrow to produce more red blood cells.

26. Aplastic anemia occurs if your bone marrow stops producing red blood cells. Aplastic anemia may be due to primary bone marrow failure, myelodysplasia (a condition in which the bone marrow produces abnormal red blood cells that do not mature properly), or occasionally as a side effect of some medications. If you appear to have a form of aplastic anemia, your doctor may refer you to a hematologist for a bone marrow biopsy to determine the cause of the anemia. Medications and blood transfusions may be used to treat aplastic anemia. Hemolytic anemia occurs when red blood cells are destroyed in the blood stream. This may be due to mechanical factors (a leaky heart valve or aneurysm), infection, or an autoimmune disease. The cause can often be identified by special blood tests and by looking at the red blood cells under a microscope. The treatment will depend upon the cause and may include referral to a heart or vascular specialist, antibiotics, or drugs that suppress the immune system.

27. Is Anemia preventable? While many types of anemia cannot be prevented, eating healthy foods can help you avoid both iron-and vitamin-deficiency anemia. Foods to include in your diet include those with high levels of iron (beef, dark green leafy vegetables, dried fruits, and nuts), vitamin B-12 (meat and dairy), and folic acid (citrus juices, dark green leafy vegetables, legumes, and fortified cereals). A daily multivitamin will also help prevent nutritional anemias ; however, older adults should not take iron supplements for iron-deficiency anemia unless instructed by their physicians .

28. REFERENCES Martin, Elizabeth A., ed. (2007).  Concise Medical Dictionary  (7th ed.).  Oxford, England :  Oxford University Press .  ISBN   978-0-19-280697-0 . Retrieved 8 September 2009. Wang, Wendy; Srivastava , Sudhir (2002). "Serological Markers". In  Lester Breslow  (ed.).  Encyclopedia of Public Health . Vol. 4.  New York, New York :  Macmillan Reference USA . pp. 1088–1090.   Dennis O'Neil (1999).  "Blood Components" .  Palomar College . Archived from  the original  on June 5, 2013. ^   Tuskegee University  (May 29, 2013).  "Chapter 9 Blood" . tuskegee.edu. Archived from  the original  on December 28, 2013. https:// www.hematology.org/education/patients/anemia K Sembullingham essentials of physiology, 6 th edition. https:// www.hematology.org/education/patients/blood-basics

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