Chapter 14 Blood

Structure & Function Blood is a type of connective tissue (consists of cells in a matrix) Function – pH – Volume – 5L (in avg. adult male) Temp. – º F. Accounts for 8% of body weight Color varies from scarlet (O 2 rich) to dark red (O 2 poor)

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

Structure The solid portion makes up 45% of a blood sample Called the hematocrit (HCT) or packed cell volume (PCV) Matrix (liquid portion) – Makes up remaining 55% of sample; mostly H 2 O, nutrients, etc.

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

Erythrocytes (RBCs) Structure: 1. biconcave disks three advantages: A. B. no point within the cytoplasm is far from the surface; ideal for gas exchange C.

Erythrocytes Structure: 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)

Hemoglobin Hb consists of the protein globin→ Each has 4 polypeptide chains & 4 heme groups (pigment) where O 2 binds Hb combines easily w/O 2 – When O 2 is released from the RBC, deoxyhemoglobin is produced; makes blood dark bluish-red

Hemoglobin Normal Hb levels – gm/100 ml of blood (in avg. adult male) Cyanosis – Symptoms – bluish lips & nail beds, dizziness, fainting, fatigue, muscle weakness

Dietary Factors for RBC Production Two B-complex vitamins (B 12 & Folic acid) are imp. for normal RBC production Both are needed for DNA synthesis Lack of B 12 – Iron (Fe) – needed for production of Hb (Vit C increases absorption of Fe in the digestive tract) Anemia –

Control of RBC Production

Life Cycle of an RBC

Destruction RBC RBC break down from wear and become ruptured when travelling through the kidney and spleen. Hemoglobin breaks down into 4 globin groups and heme groups

Destruction of RBC cont. The iron gets reused to make more hemoglobin or is stored in the liver as ferritin.