Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Chapter 11 The Blood and Body Defenses Blood • • • Represents about 8% of total body weight Average volume – 5 liters in women – 5.5 liters in men Consists of 3 types of specialized cellular elements suspended in plasma (liquid portion of blood) – Erythrocytes ◊ – ◊ – Red blood cells for O2 & CO2 transport Leukocytes White blood cells ◘ Immune system’s mobile defense units Platelets ◊ Cell fragments ◘ Important in hemostasis ♦ the process of keeping blood within a damaged blood vessel (the opposite of hemostasis is hemorrhage) Plasma 55% of whole blood Packed cell volume, or hematocrit Buffy coat: platelets and leukocytes (<1% of whole blood) Erythrocytes (45% of whole Blood) Platelets Leukocytes (white blood cells) Erythrocytes (red blood cells) Fig. 11-1, p. 298 Plasma • Plasma proteins – Compose 6% to 8% of plasma’s total weight – 3 groups of plasma proteins ◊ Albumins ◘ Most abundant plasma proteins (60%, 3.5‐5g/dl) ♦ Osmotic pressure (oncotic pressure) ♦ Transport of hormone, bile salts, bilirubin, fatty acids, calcium, transferrin, etc ♦ Tranport of many drugs – competition = drug interactions ◊ Globulins (2‐3.5g/dl) ◘ 3 subclasses ♦ Alpha1, Alpha2 (α) transport ♦ Beta (β) transport ♦ Gamma (γ) immune ◊ Fibrinogen ◘ Key factor in blood clotting Erythrocytes • Red blood cells (RBCs) – 2‐3 x 1013 ◊ 4‐5million per cc female ◊ 5‐6million per cc male – 120 day life span ….. 2 million new RBC/sec – Contain no nucleus, organelles, or ribosomes – Structure is well suited to main function of O2 transport in blood – Biconcave discs ◊ Provides larger surface area for diffusion of O2 across the membrane ◊ Thinness = short diffusion distance from exterior to innermost regions of the cell – Flexible membrane ◊ Allows RBCs to travel through narrow capillaries without rupturing in the process Hemoglobin • Found only in red blood cells • 15g/dl male 13g/dl female • Pigment containing iron – Appears reddish when oxygenated – Appears bluish when deoxygenated • Molecule consists of 2 parts – Globin portion ◊ Protein composed of four highly folded polypeptide chains – Heme groups ◊ Four iron‐containing nonprotein groups ◊ Each is bound to one of the polypeptides •Binding sites for O2 CO2 H+ •Binding of one effects affinity for the other Hemoglobin • Primary role is to carry O2 • Also combines with – Carbon dioxide – Acidic hydrogen‐ion portion (H+) of ionized carbonic acid – Carbon monoxide – Nitric oxide Erythropoiesis • • • • • Erythrocyte production RBCs survive about 120 days Spleen removes most of old erythrocytes from circulation Must be replaced at rate of 2 million to 3 million cells/second Erythropoiesis occurs in bone marrow – Pluripotent stem cells in red bone marrow differentiate into the different types of blood cells Kidney 2 1 Normal Erythropoietin 3 normal oxygencarrying capacity keeps Normally Developing erythrocytes in red bone marrow 5 4 Normal oxygencarrying capacity Erythrocytes Fig. 11-3, p. 301 Homeostasis: response to low O2 carrying capacity