Blood Functions and Composition Flashcards

Flashcards on Functions and Composition of Blood

Blood

Life-sustaining transport vehicle of the cardiovascular system.

Transport functions of Blood

Delivering O2 and nutrients to body cells, transporting metabolic wastes to lungs and kidneys for elimination, and transporting hormones from endocrine organs to target organs.

Regulation functions of Blood

Maintaining body temperature, normal pH, and adequate fluid volume.

Protection functions of Blood

Preventing blood loss and infection.

Plasma

Nonliving fluid matrix of blood.

Formed elements

Living blood cells suspended in plasma (erythrocytes, leukocytes, and platelets).

Erythrocytes

Red blood cells, ~45% of whole blood volume.

Hematocrit

Percent of blood volume that is RBCs.

Buffy coat

White blood cells and platelets, < 1% of whole blood volume.

Plasma constituents

Water, salts (electrolytes), plasma proteins (albumin, fibrinogen, globulins), nutrients, waste products, respiratory gases, and hormones.

Function of Water in Blood

Solvent carrying other substances.

Function of Salts (electrolytes) in Blood

Osmotic balance, pH buffering, regulation of membrane permeability.

Function of Albumin

Osmotic balance and pH buffering.

Function of Fibrinogen

Blood clotting.

Function of Globulins

Defense (antibodies) and lipid transport.

Function of Erythrocytes

Transport oxygen and help transport carbon dioxide.

Function of Leukocytes

Defense and immunity.

Function of Platelets

Blood clotting.

Erythrocytes

Small-diameter cells that contribute to gas transport.

Structural Characteristics of Erythrocytes

Biconcave disc shape, anucleate, essentially no organelles, filled with hemoglobin (Hb).

Hemoglobin

Binds reversibly with oxygen.

Hemoglobin composition

Red heme pigment bound to the protein globin (two alpha and two beta chains).

Erythropoiesis

Process of formation of RBCs.

Erythropoietin (EPO)

Hormone that stimulates formation of RBCs.

Leukocytes

Only formed element that is complete cell with nuclei and organelles.

Function of Leukocytes

Defense against disease.

Leukocytosis

WBC count over 11,000 per µl.

Granulocytes

Contain visible cytoplasmic granules (neutrophils, eosinophils, basophils).

Agranulocytes

Do not contain visible cytoplasmic granules (lymphocytes, monocytes).

Hemostasis

Fast series of reactions for stoppage of bleeding.

Three steps of Hemostasis

Vascular spasm, platelet plug formation, coagulation (blood clotting).

Vascular spasm

Smooth muscle contracts, causing vasoconstriction.

Platelet plug formation

Platelets release chemicals that make nearby platelets sticky; platelet plug forms.

Coagulation

Fibrin forms a mesh that traps red blood cells and platelets, forming the clot.

Human blood groups

A, B, AB, or O and an Rh factor (positive or negative).

Transfusion reactions

Mismatched transfused blood is perceived as foreign and may be agglutinated and destroyed.

ABO blood groups

RBC membranes bear different antigens (agglutinogens) that promote agglutination.

ABO blood groups antigens

Type A has only A agglutinogen, Type B has only B agglutinogen, Type AB has both A and B agglutinogens, Type O has neither A nor B agglutinogens.

ABO blood groups antibodies

Anti-A or anti-B antibodies (agglutinins) act against transfused RBCs with ABO antigens not present on recipient's RBCs.

Type O universal donor

No A or B antigens.

Type AB universal recipient

No anti-A or anti-B antibodies.

Rh blood groups

C, D, and E are most common; Rh+ indicates presence of D antigen.

Rh blood groups implications

Anti-Rh antibodies form if Rh– individual receives Rh+ blood, or Rh– mom is carrying Rh+ fetus; second exposure to Rh+ blood will result in typical transfusion reaction.

Diagnostic Blood Tests

Low hematocrit seen in cases of anemia, blood glucose tests check for diabetes, leukocytosis can signal infection.