Ch 20- The Cardiovascular System, Blood and Heart.docx

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Biological Sciences
BIO 121
Jason Ramsay

Ch 20: The Cardiovascular System, Blood and Heart - The cardiovascular system functions as a system to transport numerous substances throughout the body such as: 1. Nutrients 2. Oxygen and carbon dioxide 3. Hormones 4. Ions 5. Transports metabolic wastes to the kidneys 6. Transports leukocytes to aid in fighting infectious agents Composition of the Blood Whole Blood  Males: 4-6 liters  Females: 4-5 liters  Hypovolemic: low blood volumes  Normovolemic excessive blood volumes  pH: 7.35-7.45 Differences between plasma and interstitial fluid  Dissolved oxygen in plasma is higher  Therefore, oxygen diffuses into the tissues  Carbon dioxide concentration in plasma is lower  Therefore, carbon dioxide diffuses out of the tissues  Plasma consists of dissolved protein (interstitial fluid does not) Plasma proteins: there are three major classes of protein in the blood  60% Albumin  Contributes to the osmotic pressure, transports fatty acids and steroids, smallest of the proteins  35% Globulins  Acts as immunoglobulins (antibodies)  Act as transport proteins (transport ions and hormones)  4% Fibrinogen  Involved in blood clotting, largest of the proteins Formed Elements Red Blood Cells (RBCs) or Erthrocytes o Hermatocrit readings: the percentage of whole blood occupied by the formed elements  Males: 45% (5.4 billion RBCs per microliter)  Females: 42% (4.8 billion RBCs per microliter) o Hermatocrit readings are also called:  Packed cell volume (PVC)  Volume of packed red cells (VPRC) Structure of RBCs  Biconcave disc  Thin central region  Measure about 7.7 microns in diameter (1cm= 10,000 microns)  Lack cell organelles  Lack a nucleus (anucleated) RBC Life Span  Since RBCs lack a nucleus and all the organelles, it has a life span of about 120 days  Significance of a lack of a nucleus: - Allows the cell to be flexible as it travels through the circulatory system - Allows for more room for hemoglobin  Significance of a lack of mitochondria: o Mitochondria use oxygen to manufacture ATP o Without mitochondria, oxygen can be transported to the tissues instead of being “used” by the mitochondria RBC and Hemoglobin - A developing erythrocyte loses its nucleus and organelles - A mature erythrocyte is mainly a cell membrane surrounding water and protein o The water accounts for 66% of the RBC’s volume o The protein accounts for 33% of the RBC’s volume of which >95% is hemoglobin o Hemoglobin is responsible for transporting oxygen and carbon dioxide (the main function of RBCs) Hemoglobin - Consists of four polypeptide subunits - Each subunit contains a molecule of heme - Heme is a porphyrin ring - Each heme consists of an iron ion o Iron binds to oxygen o The polypeptide units bind to carbon dioxide o Oxygen and carbon dioxide do not compete with each other for binding sites Blood Types - Blood types are determined by the antigens on the surface of the eryth
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