Topics Discussed Today Blood components Plasma Formed elements Physical characteristics and volume of blood Functions of blood Viscosity of blood lymph 1

Components of Blood If a sample of blood is spun in a centrifuge, the heavier formed elements are packed down by centrifugal force and the less dense plasma remains at the top. plasma The tube contains anticoagulant 2

Blood has 2 components 1. Cellular component (Formed elements ). It includes: a. Erythrocytes b. Buffy coat – whitish layer present at the erythrocyte-plasma junction contains i. Leukocytes ii. Platelets 2. Liquid component (plasma). Makes about 55% of blood **Erythrocytes normally constitute 45% of the total volume of blood. This percentage is known as hematocrit. In males and females, this percentage might differ: males: 47% ± 5% females: 42% ± 5% The hematocrit tube contains anticoagulant Tube a: male blood Tube b: female blood

Plasma and Serum Plasma is the fluid portion of the blood. It contains proteins (albumins, globulins, and fibrinogen), nutrients, metabolic end products, hormones, and mineral electrolytes. ***Plasma is obtained when unclotted blood is centrifuged. The fluid above cellular elements is PLASMA. Serum is plasma from which fibrinogen and other coagulation proteins have been removed as a result of clotting. It contains high level of serotonin (released from platelets during clotting). ***It is obtained when clotted blood is centrifuged. The fluid above clotted blood is SERUM i.e Serum is the liquid part of the blood after the coagulation. 

Blood: cellular elements

Plasma proteins ***The total plasma protein is 7-8 g/dl Albumin……………....about 4.5 g/dl Globulins……………..about 2.5 g/dl (alpha, beta and gamma globulins) Fibrinogen………….. about 0.3 g/dl

Plasma Proteins (cont) - Most plasma proteins are produced by the liver, except for hormones and gamma globulins. Gamma globulins are formed by plasma cells. 8% by weight of plasma volume Plasma proteins serve a variety of functions, but they are not taken up by cells to be used as fuels or metabolic nutrients as are most other plasma solutes, such as glucose, fatty acids, and amino acids. ***Note: hypoproteinemia is seen in a. liver diseases….less formation b. kidneys disease….loss of protein 7

Plasma Proteins (cont.) - Albumin: MW= 69000 Accounts for about 60% of plasma protein It acts as a carrier of many substances in the circulation Important blood buffer Major blood protein contributing to the ONCOTIC PRESSURE (plasma osmotic pressure). This pressure helps to keep water in the bloodstream. -Globulins (alpha and beta) act as enzymes and carriers. They are produced by liver. Antibodies (Gamma globulins, Immunoglobulins) produced by plasma cells - Fibrinogen Produced by liver Forms fibrin threads of blood clot 8

Plasma Other components of plasma Nutrients and hormones Electrolytes – Ca++, K+, Cl-, HCO3-, Na+ ions Help to maintain osmotic pressure Sodium ions are the major solute contributing to blood osmotic pressure Help maintain normal blood pH Gases - CO2 and O2 O2 mostly bound to hemoglobin and CO2 bound to hemoglobin or dissolved in plasma as bicarbonate ion - Waste – such as uric acid, urea and bilirubin 9

Physical Characteristics and Volume Total blood volume: 8% of body weight Slightly alkaline pH between 7.35 and 7.45 Blood is more dense than water and about 3-4 times more viscous. Why? 10

Blood functions There are six functions: 1. Transportation O2 lungs → cells CO2 cells → lungs Nutrients GI → cells waste from cells → kidneys Blood provides O2 and nutrients to the cells and removes CO2 and other waste products from them. 11

blood Functions (cont.) 2. Defense WBCs blood proteins – antibodies 3. Temperature regulation - absorbs and distributes heat throughout body and skin 4. Prevents loss – blood clots 5. Hormone movement – endocrine gland → cells 6. Regulates pH – through buffers 12

Formed Elements The formed elements are present in the buffy coat and the bottom red layer (RBCs, WBCs and platelets). Erythrocytes have no nuclei or organelles, and platelets are cell fragments. Only leukocytes are true cells Erythrocytes and platelets do not divide. 13

Components of Whole Blood 14

Blood viscosity **Plasma is about 1.8 more viscous than water this is due mainly to presence of plasma protein. Whole blood viscosity is 3-4 times of that of water. This is due to presence of RBCs. Viscosity is increased when hematocrit value or no. of RBCs rise. **Increased viscosity will decrease blood flow through blood vessels.

lymph Special fluid originates from interstitial space, moving in lymphatic vessels and empties into general circulation (venous side) Lymph is characterized by: Contains proteins that escaped from capillaries Amount of protein depends on the area from which lymph is coming about 2 g/dl in lymph comes most tissues about 6 g/dl in lymph comes from liver about 3-4 g/dl in lymph comes intestine b. Lymph coming from intestine contains fat c. Contains clotting factors- lymph clots like blood outside body d. No red blood cells- lymph is colorless or white e. Contains white blood cells specially lymphocytes

lymph Lymph empties into venous side of circulation through Thoracic duct on left side (most of the lymph returns to circulation is through this duct) Right lymphatic duct **Lymph flow is about 120 ml / hour. Functions of lymph: 1. It returns the amount of fluid accumulated in interstitial space and by this mechanism it helps to control Interstitial fluid volume and pressure Interstitial fluid proteins 2. Route for absorption of fat from small intestine 3. Returns lymphocytes to general circulation 4. As lymph moves through lymphatic nodes the bacteria that traverse capillary wall into interstitial space will be taken and destroyed