BIO 202IN: Human Anatomy and Physiology IIChapter 17:BloodBlood Composition•Blood is a fluid connective tissue composed of•Plasma •Formed elements•Erythrocytes (red blood cells, or RBCs) •Leukocytes (white blood cells, or WBCs) •PlateletsHematocrit•Percent of blood volume that is comprised of RBCs •47% ± 5% for males•42% ± 5% for femalesPhysical Characteristics and Volume•Color: scarlet to dark red•pH 7.35 – 7.45•38C•8% of body weight•Average volume: 5–6 L for males, and 4–5 L for femalesFunctions of Blood1. Blood transports and distributes:•O2and nutrients to body cells•CO2 and metabolic wastes to the lungs and kidneys for elimination•Hormones from endocrine organs to target organs2. Blood helps regulate:•Body temperature by distributing heat•pH using buffers•Fluid volume and blood pressure3. Blood protects against:•Blood loss•Clot formation by plasma proteins and platelets •Infection •Antibodies, plasma proteins, WBCsBlood Plasma•90% water•Contains over 100 dissolved solutes•Plasma proteins are most abundant solutes and mostly produced by the liver and remain in blood•60% albumin: carrier molecules in blood, major contributor to blood osmolality•36% globulins: gamma globulins are antibodies3/25/2020Page 1
BIO 202IN: Human Anatomy and Physiology II•4% fibrinogen: clotting factor•Nitrogenous waste products like lactic acid and urea•Nutrients like glucose, amino acids, and fatty acids•Electrolytes like Na+, K+, Ca2+, Cl–, HCO3–•Respiratory gases: O2and CO2•Hormones like estrogen, testosterone and insulinFormed Elements•Cellular component of blood•WBCs, RBCs and platelets•Formed elements originate in bone marrow •Most formed elements have a limited lifespanErythrocytes•Designed for gas transport•Biconcave discs, no nucleus or other common organelles•Filled with hemoglobin (Hb) •Plasma membrane proteins provide flexibility and all RBC to change shape •Are the major factor contributing to blood viscosity•Structural characteristics contribute to gas transport •Biconcave shape: increases surface area relative to volume•97% hemoglobin (not counting water)•No mitochondria; ATP production is anaerobic•A superb example of the complementarity of structure and function Erythrocyte Function•RBCs transport respiratory gases (O2 and CO2) transport•Hemoglobin binds reversibly with oxygen Hemoglobin structure•Hemoglobin is mostly protein•Globin is the protein component•Heme pigment bonded to each globin chain•Iron atom in the center each heme can bind to one O2molecule•There are 4 hemes per hemoglobin molecule•Therefore each Hb molecule can transport four O2Hemoglobin (Hb)•O2loading in the lungs•Produces oxyhemoglobin (ruby red)•O2unloading in the tissues•Produces deoxyhemoglobin or reduced hemoglobin (dark red) 3/25/2020Page 2
BIO 202IN: Human Anatomy and Physiology II•CO2loading in the tissues•Produces carbaminohemoglobin (binds to protein part of hemoglobin)•
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