Laboratory 1.1 - Functions of Blood

Hematology

The study of blood

Transportation function of blood (Lab 1.1)

Blood carries gases (oxygen from lungs to the body, carbon dioxide back for exhalation), nutrients, hormones, and waste products to the proper systems for utilization or excretion

Regulation function of blood (Lab 1.1)

Blood helps regulate body temperature, fluid balance, and the body's pH level

Protection function of blood (Lab 1.1)

White blood cells defend the body against infection, while platelets and clotting factors stop bleeding and prevent blood loss via clotting

Cellular communication function of blood (Lab 1.1)

Blood carries hormones and signaling molecules, facilitating communication between different parts of the body

Plasma (Lab 1.1)

The liquid portion of blood, making up about 55% of its total volume; primarily water but contains dissolved proteins, glucose, clotting factors, electrolytes, hormones, carbon dioxide, and oxygen

Formed elements (Lab 1.1)

The solid components of blood, comprising about 45% of its volume; includes erythrocytes, leukocytes, and thrombocytes

Erythrocytes (Lab 1.1)

Red blood cells; carry oxygen to the body's tissues and remove carbon dioxide; contain hemoglobin, a protein that binds to oxygen

Leukocytes (Lab 1.1)

White blood cells; part of the immune system, protecting the body against infectious disease and foreign invaders

Thrombocytes (Lab 1.1)

Platelets; cell fragments essential for blood clotting and wound healing

Standard Precautions

Safety precautions published by the CDC and OSHA in which individuals handling blood and body fluids assume they are infectious and take steps to protect against exposure to bloodborne pathogens

Hematocrit

A blood test that measures the proportion of red blood cells (RBCs) in the blood, typically expressed as a percentage of the total blood volume

Hematocrit procedure

A drop of blood is placed into a heparinized capillary tube and sealed, the tube is spun in a centrifuge to separate blood components, and a microhematocrit reader is used to determine the percentage of RBCs, buffy coat, and plasma

Blood layers after centrifugation

Plasma (top, light yellow layer, about 55% of blood volume, containing water, electrolytes, proteins, hormones, and waste products), buffy coat (thin middle layer of white blood cells and platelets), and red blood cells (bottom layer, largest portion of blood volume)

Buffy coat

The thin, middle layer formed after centrifugation, consisting of white blood cells and platelets

Normal hematocrit ranges

Males: 40.7% to 50.3%; Females: 36.1% to 44.3%; differences are largely due to hormonal variations, especially testosterone (which stimulates RBC production), and menstruating females losing blood monthly

Hematocrit clinical significance

A high hematocrit might indicate dehydration or polycythemia vera, while a low hematocrit could be a sign of anemia or blood loss; the hematocrit itself cannot be used to make a diagnosis but can indicate an abnormality alongside other tests

Factors that increase the hematocrit

Dehydration, change in elevation, increased exercise, and polycythemia vera

Factors that decrease the hematocrit

Anemia, recent bleeding (including menstruation), vitamin or mineral deficiencies that affect RBC production, and cirrhosis of the liver (affects iron)

Hematocrit calculation formula

Length of formed element divided by length of original column of blood, multiplied by 100