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Chapter 14

Chapter 14. Blood. Structure & Function. Blood is a type of connective tissue (consists of cells in a matrix) Function – transports O 2 & nutrients, maintains homeostasis, protection from blood loss & infection pH – 7.35-7.45 Volume – 5L (in avg. adult male) Temp. – 100.4 º F.

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Chapter 14

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  1. Chapter 14 Blood

  2. Structure & Function • Blood is a type of connective tissue (consists of cells in a matrix) • Function – transports O2 & nutrients, maintains homeostasis, protection from blood loss & infection • pH – 7.35-7.45 • Volume – 5L (in avg. adult male) • Temp. – 100.4 º F. • Accounts for 8% of body weight • Color varies from scarlet (O2 rich) to dark red (O2 poor)

  3. Structure • Composition – • composed of 3 types of cells (called solid portion): • 1. RBCs – erythrocytes • 2. WBCs – leukocytes • 3. platelets - thrombocytes

  4. Structure • The solid portion makes up 45% of a blood sample • Called the hematocrit (HCT) or packed cell volume (PCV) • Matrix (liquid portion) – plasma; clear,straw-colored • Makes up remaining 55% of sample; mostly H2O, nutrients, etc.

  5. Hematopoiesis – Production of blood cells (RBCs, WBCs & platelets)

  6. Erythrocytes (RBCs) • Structure: • 1. biconcave disks • three advantages: A. increase SA B. no point within the cytoplasm is far from the surface; ideal for gas exchange C. flexible; can squeeze thru tiny b.v.

  7. Erythrocytes • Structure: • 2. Contain hemoglobin (Hb); allows them to carry resp. gases more efficiently • 3. Mature RBCs lack nuclei; allows more room for Hb (each RBC is 1/3 Hb by volume) • Normal RBC count: 4-6 million/mm³ of blood (in avg. adult) (slight incr. after meals or exercise; decr. from anemia, leukemia, or hemorrhage)

  8. Hemoglobin • Hb consists of the protein globin→ • Each has 4 polypeptide chains & 4 heme groups (pigment) where O2 binds • Hb combines easily w/O2 – called affinity ( or attraction) for O2 • Produces oxyhemoglobin; makes blood bright red • When O2 is released from the RBC, deoxyhemoglobin is produced; makes blood dark bluish-red

  9. Hemoglobin • Normal Hb levels – 14-18 gm/100 ml of blood (in avg. adult male) • Cyanosis – occurs when O2 is deficient (hypoxia) & levels of deoxyhemoglobin incr. • Symptoms – bluish lips & nail beds, dizziness, fainting, fatigue, muscle weakness

  10. Dietary Factors for RBC Production • Two B-complex vitamins (B12 & Folic acid) are imp. for normal RBC production • Both are needed for DNA synthesis • Lack of B12 – usually caused by a disorder of the stomach lining not producing sufficient intrinsic factor (substance needed for B12 absorption) • Iron (Fe) – needed for production of Hb (Vit C increases absorption of Fe in the digestive tract) • Anemia – deficiency or destruction of RBCs (see Table 14.4 – Types of Anemia in text)

  11. Control of RBC Production

  12. Life Cycle of an RBC

  13. Destruction RBC • RBC break down from wear and become ruptured when travelling through the kidney and spleen. • Macrophages break down RBC and their contents. • Hemoglobin breaks down into 4 globin groups and heme groups • Heme breaks down into biliverdin (green pigment)

  14. Destruction of RBC cont. • Biliverdin breaks down into bilirubin (orange) • The iron gets reused to make more hemoglobin or is stored in the liver as ferritin.

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