Blood Composition & Functions: Erythrocytes, Leukocytes, Platelets, Plasma & Proteins, Slides of Anatomy

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Blood

Blood

 Considered a connective tissue: contains

 Cells  a liquid ground substance (called plasma)  dissolved protein fibers.

 About four times more viscous (or thicker)

than water.

 Temperature of blood is about 1°C higher

than measured body temperature.

Components of Blood

 Erythrocytes (or red blood cells)  form the lower layer of the centrifuged blood  typically make up about 44% of a blood sample  Buffy coat  makes up the middle layer  thin, slightly gray-white layer composed of cells called leukocytes (or white blood cells) and cell fragments called platelets  forms less than 1% of a blood sample  Plasma  straw-colored liquid that rises to the top  generally makes up about 55% of blood

Functions of Blood –

Transportation

 Transports numerous elements and compounds throughout the body.  erythrocytes carry oxygen from the lungs to body cells and then transport carbon dioxide from the cells back to the lungs for expulsion from the body  blood plasma  transports nutrients that have been absorbed from the GI tract  hormones secreted by the endocrine organs to their target cells  plasma  carries waste products from the cells to organs such as the kidneys, where these waste products are removed

Functions of Blood –

Regulation of pH Levels

 pH is a measure of how alkaline or acidic a fluid is.  Neutral pH is measured at exactly 7.  Acidic fluids (e.g., orange juice) are between 0 and 7.  Alkaline fluids (e.g., milk) are between 7 and 14.  Blood plasma contains compounds and ions that may be distributed to the fluid among tissues (interstitial fluid) to help maintain normal tissue pH.  Blood plasma pH is continuously regulated at a value of 7.4 the pH level required for normal cellular functioning.

Functions of Blood –

Maintenance of Fluid Levels

 Maintains normal fluid levels in the cardiovascular system.  Prevents fluid loss.  Constant exchange of fluid between the blood plasma and the interstitial fluid.  If too much fluid is absorbed in the blood, high blood pressure results.  If too much fluid escapes the bloodstream and enters the tissues, blood pressure drops to unhealthy low levels, and the tissues swell with excess fluid.

Functions of Blood –

Protection

 Leukocytes (white blood cells) help guard against infection by mounting an immune response if a pathogen or an antigen is found.  Plasma transports antibodies, which are molecules that can immobilize antigens until a leukocyte can completely kill or remove the antigen.  Platelets and blood proteins protect the body against blood loss by forming blood clots on damaged vessels.

Components of Plasma

 Complex mixture of water, proteins, and other solutes.

 When the proteins are moved from plasma, the remaining fluid is termed serum.

 Water makes up about 92% of plasma’s total volume.  water facilitates the transport of materials in the plasma

Plasma Proteins – Albumins

 Smallest and most abundant of the plasma proteins.  make up approximately 58% of total plasma proteins  Regulate water movement between the blood and interstitial fluid.  Albumins act as transport proteins that carry ions, hormones, and some lipids in the blood.

Plasma Proteins – Globulins

 Second largest group of plasma proteins, forming about 37% of all plasma proteins.  Smaller alpha-globulins and the larger beta-globulins primarily bind, support, and protect certain water- insoluble or hydrophobic molecules, hormones, and ions.  Gamma-globulins: Also called immunoglobulins or antibodies.  Produced by some of our defense cells to protect the body against pathogens that may cause disease.

Plasma Proteins – Regulatory

Proteins

 Form a very minor class of plasma proteins.  <1% of total plasma proteins  Include enzymes to accelerate chemical reactions in the blood and hormones being transported throughout the body to target cells.

Solutes

 Plasma is an extracellular fluid (ECF).  it includes all body fluids that are not found inside cells  Plasma is somewhat like interstitial fluid, in that  both have similar concentrations of nutrients, waste products, and electrolytes  Concentration of dissolved oxygen is higher in plasma than in interstitial fluid, because the cells take up and use the oxygen from the interstitial fluid during energy production.