General Functions and Composition of Blood

Comprehensive set of practice flashcards created from Dr. Eman Basha's lecture on general functions, composition, properties, cellular elements, and hematocrit value of blood.

What is blood and what is its average volume in a $70\,kg$ person?

Blood is a vital fluid that circulates within the Cardiovascular system (also called the river of life). Its total volume is about $8\%$ of body weight, with an average of about $5\,L$ in a $70\,kg$ person.

What are the two main components of blood and their relative percentages?

Blood is formed of Plasma ($55\%$ of total blood volume, $5\%$ of total body weight) and Cellular elements ($45\%$ of total blood volume).

What is the normal osmolality of plasma and what are two examples of isotonic solutions?

Plasma osmolality equals $285\text{-}295\,mOsm/kg$. Examples of isotonic solutions (solutions with osmolality equal to plasma) are $0.9\%$ NaCl and $5\%$ glucose.

What is the difference in definition and composition between Serum and Plasma?

Serum is the liquid portion of blood after it has clotted and lacks clotting factors like fibrinogen ($\text{Serum} = \text{Plasma} - \text{clotting factors}$). Plasma is the liquid portion obtained after centrifuging anticoagulated blood and contains clotting factors like fibrinogen ($\text{Plasma} = \text{Blood} - \text{Blood cells}$).

What are the normal RBC counts for adult males and adult females?

In adult males: $5\text{ to }5.5\text{ million / mm}^3$. In adult females: $4.5\text{ to }5\text{ million / mm}^3$.

What are the types of granular and non-granular leucocytes?

Granular leucocytes include Basophil, Eosinophils, and Neutrophils. Non granular leucocytes include Monocytes and lymphocytes.

What are the pH values for arterial blood and venous blood?

The pH of arterial blood is $7.4$, and the pH of venous blood is $7.3$.

How is blood viscosity characterized in comparison to water and plasma?

Blood viscosity is $5$ times that of water (due to red blood cells and plasma proteins). Plasma viscosity is $2$ times that of water (due to plasma proteins). Blood viscosity is necessary for maintaining normal arterial blood pressure.

What are the specific gravity values of Erythrocytes, Whole blood, and Plasma?

Erythrocytes: $1090$; Whole blood: $1060$; Plasma: $1030$.

What are the four transport functions of blood?

1) Nutrition: Transports nutrients from the GIT to tissues. 2) Respiration: Transports $O_2$ from lungs to tissues and $CO_2$ from tissues to lungs. 3) Excretion: Transports metabolic waste products from tissues to excretory organs. 4) Regulation of metabolism: Transports hormones from endocrine glands to target tissues.

What mechanisms allow blood to regulate body temperature?

a) Body fluid stores a great quantity of heat. b) Blood distributes heat all over the body and carries heat to the surface for elimination. c) Blood supplies water for cutaneous and pulmonary evaporation.

What are the structural dimensions and average lifespan of RBCs?

RBCs are biconcave disc-like structures with no nucleus, a diameter of $7.5\,\text{micron}$, and a thickness of $2.2\,\text{micron}$. They survive for approximately $120\,\text{days}$ in peripheral blood.

What are the three main functions of hemoglobin?

1) Binds oxygen loosely to the iron of the haem molecule to carry $O_2$ from lungs to tissues. 2) Binds $CO_2$ to the globin part to carry $CO_2$ from tissues to lungs. 3) Acts as a strong buffer to prevent changes in blood pH.

What are the four harmful effects of free hemoglobin in plasma resulting from intravascular hemolysis?

a) Filtered by renal glomeruli, blocking renal tubules and causing renal failure. b) Increased blood viscosity, increasing workload on the heart. c) Increased colloid Osmotic Pressure (COP), increasing blood volume and workload on the heart. d) Destruction by reticuloendothelial system, increasing bilirubin formation and causing jaundice.

What are the main functions of Neutrophils, Eosinophils, and Basophils?

Neutrophils: Phagocytosis of bacteria and first line of defense in acute infection. Eosinophils: Defense against parasites and modulation of allergic reactions. Basophils: Release histamine and heparin.

What are the main functions of Monocytes and Lymphocytes?

Monocytes (Macrophages): Phagocytosis, antigen presentation, and tissue repair. Lymphocytes: T cells (cell-mediated immunity), B cells (antibody production), and NK cells (kill virus-infected and tumor cells).

What is the definition of Hematocrit value (packed cell volume) and its normal average values across different groups?

Hematocrit value is the percentage of red blood volume in relation to whole blood volume. Normal averages: Males: $45\%$, Females: $42\%$, Newborn: $55\%$, Child: $36\%$.

Why do Hematocrit values differ in males, females, newborns, and children?

Males are higher than females because testosterone hormone stimulates erythropoiesis. Females are lower due to RBC loss in the menstrual cycle. Newborns are higher because hypoxia stimulates erythropoiesis. Children are lower due to iron depletion in tissue building.

What conditions cause an increase or decrease in Hematocrit value?

Increased in polycythemia (increased RBC count) and dehydration (decreased plasma volume). Decreased in anemia (decreased RBC count) and overhydration (excessive intravenous fluids infusion).