Bio 235 Lecture Exam-1 Study Guide - Chapter 17 Blood Blood Composition Blood Fluid connective tissue Plasma non-living fluid matrix Formed elements

Bio 235 Lecture Exam-1 Study Guide - Chapter 17 Blood Blood...

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Chapter 17 Blood Blood Composition Blood Fluid connective tissue Plasma – non-living fluid matrix Formed elements – living blood "cells" suspended in plasma Erythrocytes (red blood cells, or RBCs) Leukocytes (white blood cells, or WBCs) Platelets Spun tube of blood yields three layers Plasma on top (~55%) Erythrocytes on bottom (~45%) WBCs and platelets in Buffy coat (< 1%) Hematocrit Percent of blood volume that is RBCs 47% ± 5% for males; 42% ± 5% for females Physical Characteristics and Volume Sticky, opaque fluid with metallic taste Color varies with O 2 content High O 2 - scarlet; Low O 2 - dark red pH 7.35–7.45 ~8% of body weight Average volume 5–6 L for males; 4–5 L for females Functions of Blood Functions include Distributing substances Regulating blood levels of substances Protection Distribution Functions Delivering O 2 and nutrients to body cells Transporting metabolic wastes to lungs and kidneys for elimination
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Transporting hormones from endocrine organs to target organs Regulation Functions Maintaining body temperature by absorbing and distributing heat Maintaining normal pH using buffers; alkaline reserve of bicarbonate ions Maintaining adequate fluid volume in circulatory system Protection Functions Preventing blood loss Plasma proteins and platelets initiate clot formation Preventing infection Antibodies Complement proteins WBCs Blood Plasma 90% water Over 100 dissolved solutes Nutrients, gases, hormones, wastes, proteins, inorganic ions Plasma proteins most abundant solutes • Remain in blood; not taken up by cells • Proteins produced mostly by liver • 60% albumin; 36% globulins; 4% fibrinogen Albumin 60% of plasma protein Functions Substance carrier Blood buffer Major contributor of plasma osmotic pressure Formed Elements Only WBCs are complete cells RBCs have no nuclei or other organelles Platelets are cell fragments Most formed elements survive in bloodstream only few days Most blood cells originate in bone marrow and do not divide
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Erythrocytes Biconcave discs, anucleate, essentially no organelles Diameters larger than some capillaries Filled with hemoglobin (Hb) for gas transport Contain plasma membrane protein spectrin and other proteins Spectrin provides flexibility to change shape Major factor contributing to blood viscosity Structural characteristics contribute to gas transport Biconcave shape—huge surface area relative to volume >97% hemoglobin (not counting water) No mitochondria; ATP production anaerobic; do not consume O 2 they transport Superb example of complementarity of structure and function Erythrocyte Function RBCs dedicated to respiratory gas transport Hemoglobin binds reversibly with oxygen Normal values Males - 13–18g/100ml; Females - 12–16 g/100ml Hemoglobin Structure Globin composed of 4 polypeptide chains
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