Blood Flashcards
Blood
consists of blood plasma & formed elements (cells and cell fragments)
approx. 6L in adults or 7% of total body weight
fn:
1. transportation: gases, nutrients, hormones, waste products
2. maintenance of homeostasis: pH, body temperature, osmotic pressure
3. protection: clotting, white blood cells, proteins
Blood Plasma
albumins: maintains blood osmolarity
globulins: transport ions, immune fn
fibrinogens: involved in clotting
Erythorocytes
fraction (by volume) of blood occupied by RBCs is the hematocrit
no nuclei or typical organelles; largely cytoskeleton & cytoplasm
biconcave disc shape; increases flexibility and surface area/volume ratio
120-day life cycle due to wear & tear & inability to synthesize new components
Hemoglobin (Hb)
each RBC contains ~270 million Hb molecules
consists of 4 globular protein subunits + 4 non-proteins pigments called hemes, each with a single Fe++ ion
Blood Typing: ABO grouping
characterized by presence or absence of antigens on the plasma membrane of RBCs
antibodies against missing antigens present in plasma without prior exposure
Blood Typing: Rh Grouping
people that have Rh (D) antigens are Rh+ & people who lack it are Rh-
normally blood plasma does not contain anti-Rh antibodies; produced only after exposure to Rh+ blood
Typing of Blood
- drops of blood are mixed with different antisera
- Agglutination with an antisera indicates presence of that antigen on the RBC
- ABO & Rh+ blood types are typically reported together
Leukocytes
circulate in blood & are scattered in peripheral tissues
defend body against pathogens, remove wastes, & damaged cells
short life span, undergo apoptosis in CT
enter tissues in response to chemotactic signals & due to changes in expression of endothelial cell surface receptors which are induced by mediators of acute inflammation
Neutrophils
50-70%
1 nucleus with a # of lobes, pale granules in cytoplasm
granules packed with lysosomal enzymes & bacterial compound
fn: kill & phagocytose bacteria & breakdown releases chemotactic signals
Lymphocyte
20-25%
round, heterochromatic nucleus, very little cytoplasm
blood lymphocytes account for a fraction lymphocytes; remainder in peripheral tissues & the lymphatic system
only WBCs that reticulate
fn: responsible for specific immunity, include B, T, & NK cells
Monocytes
3-8% of WBCs
kidney shaped nucleus, clear cytoplasm, largest WBC
circulate for only a few days, enter CT spaces, differentiate into macrophages
fn: phagocytose dead cells, antigens, & bacteria, & release chemotactic agents which attract other phagocytes
Eosinophils
s increase with allergic reaction & parasitic infections
2-4%
bilobed nucleus, bright orange-red granules
fn: phagocytic cells attracted to antigen/antibody complexes & parasitic worms
Basophils
<1% of WBCs
Bilobed nucleus, often obscured by basophilic granules
modulate inflammation
accumulate within damaged tissues; discharge granules into interstitial fluid
granules contain:
- histamine
- heparin
- chemotactic factors
Platelets
small, membrane bound, anucleate cytoplasmic fragments
shed by megakaryocytes in red bone marrow & continually replaced
important role in blood clotting: initiate & control process by releasing enzymes, forms temporary plug & involved in active contraction of formed clot
