Blood

What is Homeostasis It is the internal environment (and therefore survival itself) Maintaining homeostasis is dependent on continual transportation of materials to and from body cells. Blood is a complex solution and is vital to your ability to survive.

Composition and Function of Blood Composed of plasma (55%) and formed elements (45%) Used for transport of materials through the body Used to regulate body heat (homeostasis)

How much blood do you have? Amount of blood varies based on Age Body type Gender 1 unit of blood = 0.5 liters

Solution = Solvent + Solute Plasma Liquid part of the blood – it is a solution Remember…….. Solution = Solvent + Solute Composed of water (90%) and mostly proteins (10%)

Solutes found in Plasma Roughly 6% to 8% of the solutes found in plasma are made of protein. Examples: Albumins Globulins Fibrogen

Formed Elements of the Blood Formed elements are all the chemicals (usually proteins) and cells found in the blood. The formed elements are: Erythrocytes (Red Blood Cells) Leukocytes (White Blood Cells) Platelets (Cell fragments)

Erythrocytes Also called Red Blood cells Have no nucleus Thin plasma membrane Do not have ribosomes and mitochondria as well as other organelles Shaped as a biconcave disk 7.5 mm in diameter Filled with hemoglobin (Hb) Most numerous formed element

Function of Erythrocytes Transport oxygen and carbon dioxide Ability to transport oxygen and carbon dioxide is based on the amount of hemoglobin

Hemoglobin Hb is made of 4 globin protein chains – two alpha and two beta. (Fig 17-5, p. 533) 4 oxygen molecules carried by each Hb molecule Normal Hb values: Males: 14 g to 16 g/100 ml blood Females: 12 g to 14 g/100 ml blood Anemia—less than 10 g/100 ml blood

Erythropoiesis – The Formation of Erythrocytes Begins in the red bone marrow as hemopoietic stem cells (hemocytoblast) go through several stages of development to become erythrocytes Process takes about 4 days to complete. Stimulus for increased RBC formation is low oxygen levels in the kidney Stimulus for RBC formation is erythropoietin, produced continually by liver Erythropoietin stimulates the hemocytoblasts to produce more RBCs

Destruction of Erythrocytes RBCs last about 105 to 120 days Macrophage cells in the liver and spleen phagocytose the old, abnormal or damaged cells. Hemoglobin is broken down releasing the iron, amino acids and bilirubin. Most components are recycled

Formed Element – Leukocytes (WBC) Two major groups: Granulocytes and Agranulocytes Granulocytes have granules in cytoplasm and lobed nuclei (p. 538) Agranulocytes do not have granules in their cytoplasm (p. 536)

Types of Granulocytes - Neutrophils Neutrophils: 65%–75% of total WBCs (Fig. 17-9) Highly mobile and very active phagocytic cells Cytoplasmic granules contain lysosomes. Increase in numbers during acute infections

Types of Granulocytes - Eosinophils Eosinophils: 2%–5% of circulating WBCs (Fig. 17-10) Numerous in lining of respiratory and digestive tract Capable of ingesting inflammatory chemicals and proteins Increase in numbers during allergic reactions and parasitic worm infections

Types of Granulocytes - Basophils Basophils: 0.5%–1% of total WBCs (Fig. 17-11) Motile Cytoplasmic granules contain histamine and heparin. Increase in numbers during allergic reactions and periods of inflammation

Types of Agranulocytes - Lymphocyte Lymphocytes: 20%–25% of total WBCs (Fig. 17-12) Two types of Lymphocytes are important in the immune response Thymic lymphocytes (T lymphocytes, or T cells) Bursal lymphocytes (B lymphocytes, or B cells)

Types of Agranulocytes - Monocyte Monocytes: 3%–8% of total WBCs (Fig. 17-13) Become macrophages in the tissues

Formation of Leukocytes Both Granular and Agranular Leukocytes mature from undifferentiated Hemopoietic adult stem cells (hemocytoblasts) The hemocytoblasts that development neutrophils, eosinophils, basophils, and some lymphocytes and monocytes are found in red marrow Other heomocytoblasts found in Lymphoid tissue develop into lymphocytes and monocytes.

Thrombocytes (Platelets) In circulating blood, platelets are small, pale bodies that appear as irregular spindles or oval disks. Plasma membrane-bound particles of cytoplasm containing clotting factors 2 to 4 mm in diameter Three important properties Agglutination – “clumping” Adhesiveness – “sticking” Aggregation – “together”

Thrombocytes (Platelets) Function Important role in hemostasis and blood coagulation Two major functions are: Hemostasis = stoppage of blood flow. Platelet plug formed by platelets sticking together (sticky platelets) Coagulation = formation of fibrin clot

Formation of Thrombocytes Formed in Red Bone Marrow, lungs and spleen. Hemopoietic adult stem cells (hemocytoblasts) form megakaryoblasts, which form megakaryocytes, from these form membrane-bound cytoplasmic fragments (platelets). Average survival about 7 days

Blood Type Antigens

How does Blood Clot? https://www.youtube.com/watch?feature=player_embedded&v=--bZUeb83uU