Consists of heart (pump), blood vessels, and blood
Picks up nutrients from digestive system
Exchanges gases with respiratory system
Delivers nutrients and O2 to every cell
Carries CO2 to lungs for removal
Carries wastes and excess water to urinary system
Carries metabolic wastes to liver for removal
Helps regulate body temperature
The Composition and Functions of Blood:
Blood is a specialized connective tissue consisting of
– Specialized cells and cell fragments
– Watery solution of ions, molecules
Blood has three primary functions
– Transportation of nutrients, waste, hormones
– Regulation of body temperature, water volume, pH
– Defense against infections and bleeding
Plasma (makes up 55% of whole blood)
– Water
– Electrolytes (ions)
– Proteins (albumins, globulins, clotting proteins)
– Hormones
– Gases
– Nutrients and wastes
Formed elements (makes up 45% of whole blood)
– Red blood cells (RBCs)
– White blood cells (WBCs)
– Platelets
Plasma Consists of Water and Dissolved Solutes:
Plasma: liquid portion of the blood
90% water
10% dissolved solutes
– Proteins
– Hormones
– Ions
– Amino acids
, – Carbohydrates
– Vitamins
– Metabolic wastes
Plasma proteins
– Albumins: maintain osmotic balance with interstitial fluid
– Globulins: diverse group of proteins
– Alpha
– Beta globulins: important transport functions
– Bind to lipid-forming lipoproteins
– HDL: high-density lipoproteins
– LDL: low-density lipoproteins (“bad cholesterol”)
– Gamma globulins: antibodies that are part of the body’s defenses against
infections
– Clotting proteins
Red Blood Cells (Erythrocytes) Transport Oxygen and Carbon Dioxide:
Make up almost half the blood volume
5 million/mm3
Functions: transport oxygen (O2) and carbon dioxide (CO2)
Packed with hemoglobin, a protein which transports O2
Hemoglobin molecule includes heme groups that each have iron atoms to which O2
binds
Origin: stem cells in the bone marrow
Life span: 120 days in humans
Control of production: erythropoietin (hormone)
Hematocrit and Hemoglobin Reflect Oxygen-Carrying Capacity:
Hematocrit: the percentage of whole blood that consists of red blood cells
– Men: 43–49% Women: 37–43%
Hemoglobin measurement
– Men: 14–18 gm% Women: 12–14 gm%
Low hematocrit or hemoglobin may indicate anemia
High hematocrit may be response to high elevation (less O2 available in atmosphere)
Very high hematocrit is risky because of increased blood viscosity
Blood Cells and Platelets Originate From Stem Cells:
Stem cells in bone marrow divide continually throughout the life of an individual
These stem cells produce all of the types of blood cells
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