Blood and Its Functions

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Questions and Answers

What is the primary function of plasma proteins related to fluid balance in the body?

Prevent excessive loss of plasma fluid (correct)

Carry oxygen in the blood

Provide energy to cells

Aid in nutrient absorption

What percentage of blood is composed of plasma?

55% (correct)

50%

60%

45%

Which plasma protein is primarily responsible for the oncotic pressure in blood?

Fibrinogen

Globulin

Prothrombin

Albumin (correct)

Which of the following statements about blood's hemostatic function is true?

Fibrinogen and prothrombin are essential for clotting. Signup and view all the answers

What is the normal albumin/globulin (A/G) ratio in healthy adults?

1.2–1.6 Signup and view all the answers

Which component of blood plays a critical role in the immune response?

γ Globulins Signup and view all the answers

What is the role of plasma proteins during starvation?

They serve as a source of proteins. Signup and view all the answers

How does a decrease in albumin levels affect tissue fluid balance?

It leads to edema from increased fluid filtration. Signup and view all the answers

What is the role of intrinsic factor in relation to Vitamin B12?

It forms a complex with Vitamin B12 for absorption. Signup and view all the answers

Which of the following is NOT a cause of microcytic hypochromic anemia?

Aplastic anemia caused by bone marrow depression. Signup and view all the answers

What characterizes macrocytic (megaloblastic) anemia?

Presence of large-sized RBCs. Signup and view all the answers

What is a common symptom of anemia?

Pallor. Signup and view all the answers

What is the typical lifespan of red blood cells (RBCs)?

120 days. Signup and view all the answers

Which trace element is specifically mentioned as important in the content provided?

Copper. Signup and view all the answers

How is hemoglobin processed in the body after erythrocyte hemolysis?

Phagocytized by macrophages. Signup and view all the answers

What is a primary cause of hemorrhagic anemia?

Acute blood loss. Signup and view all the answers

What can cause Vitamin B12 deficiency anemia?

Decrease intake in pure vegetarians Signup and view all the answers

Which of the following statements is true regarding blood groups?

Group B individuals have anti-A antibodies Signup and view all the answers

Incompatible blood transfusion occurs due to the presence of which component?

Agglutinins against matching antigens Signup and view all the answers

What is the Rh factor associated with?

The presence of D antigen Signup and view all the answers

What is the universal donor blood group and why?

Group O because it lacks A and B antigens Signup and view all the answers

Erythroblastosis Fetalis can occur in which scenario?

When Rh -ve female carries a Rh +ve fetus Signup and view all the answers

Which condition is likely caused by folic acid deficiency?

Macrocytic anemia Signup and view all the answers

What occurs in the maternal circulation when Rh -ve and Rh +ve blood mixes during birth?

Anti-D antibodies are produced Signup and view all the answers

What is the primary purpose of hemoglobin in red blood cells?

Transport oxygen and carbon dioxide Signup and view all the answers

What shape are normal red blood corpuscles, and why is this shape beneficial?

Biconcave disc; increases surface area for gas diffusion Signup and view all the answers

Which factor plays a significant role in stimulating erythropoiesis?

Erythropoietin hormone Signup and view all the answers

In which part of the body do RBCs primarily develop in adults over the age of 20?

Bone marrow of flat bones Signup and view all the answers

What is the average volume of a red blood cell (RBC) in femtoliters (fL)?

90 fL Signup and view all the answers

What is the iron form that is primarily absorbed in the small intestine?

Ferrous Fe2+ Signup and view all the answers

What is the mean corpuscular hemoglobin concentration (MCHC) range in grams per deciliter (g/dL)?

31-36 g/dL Signup and view all the answers

What structural components make up hemoglobin?

Globin and heme Signup and view all the answers

Study Notes

Blood Overview

Blood is essential for the cardiovascular system, with a volume of approximately 5-5.5 liters in adults.
Composed of plasma (55%) and cells (45%): including red blood cells (RBCs), white blood cells (WBCs), and platelets.

Functions of Blood

Transport: Carries oxygen (O2), carbon dioxide (CO2), nutrients like glucose.
Defense: WBCs and antibodies combat pathogens.
Hemostasis: Platelets and clotting factors manage bleeding.
Homeostasis: Regulates body temperature and pH levels.

Plasma Composition

Water: Makes up 90% of plasma.
Organic Substances: Includes plasma proteins, glucose, and lipids.
Inorganic Substances: Includes sodium (Na+) and chloride (Cl-).
Gases: Contains O2 and CO2.

Plasma Proteins

Total concentration: 7.2–7.4 g/dL.
Albumin: 3.5-5 g/dL; most abundant and smallest protein.
Globulins: 2.5 g/dL; includes α1, α2, β, and γ globulins.
Formed primarily in the liver, except for γ globulins which are immune antibodies.
A/G Ratio: Normal range 1.2–1.6; decreases in liver and kidney disease.

Functions of Plasma Proteins

Osmotic Function: Oncotic pressure (~25 mmHg), mainly due to albumin, prevents excessive fluid loss from capillaries; low levels can lead to edema.
Transport: Carries vitamins, minerals, and hormones.
Defense: γ globulins act as antibodies.
Hemostasis: Involves fibrinogen and prothrombin for clotting.
Buffering: Maintains blood pH around 7.4.
Nutritional Reserve: Provides proteins during starvation.

Erythrocytes (RBCs)

Hematocrit Value: Approximately 45% RBC volume in total blood.
RBC Count: 5.5 million/mm³ in males, 5 million/mm³ in females.
Shape & Size: Biconcave disks of about 90 fL volume; enhances gas diffusion and flexibility in capillaries.
RBCs lack organelles and a nucleus, maximizing hemoglobin capacity.

Hemoglobin (Hb)

Hb Concentration: 15-16 g/dL in males, 13-14 g/dL in females.
Structure: Composed of globin (four chains) and heme (containing iron).
Functions: Transports O2 and CO2; provides buffering capacity for pH.

Blood Indices

Mean Corpuscular Volume (MCV): 80-95 fL.
Mean Corpuscular Hemoglobin (MCH): 26-32 pg.
Mean Corpuscular Hemoglobin Concentration (MCHC): 31-36 g/dL.

Erythropoiesis (RBC Production)

Sites of Production: Liver and spleen in fetuses; all bones in children; specific bones (skull, sternum, ribs, vertebrae, hip bones) in adults.
Process: Hemopoietic stem cells mature into reticulocytes before becoming erythrocytes.

Factors Affecting Erythropoiesis

Healthy bone marrow and erythropoietin hormone (produced by liver and kidneys in response to hypoxia).
Nutrients: Iron, Vitamin B12, folic acid, and high biological value proteins are essential for RBC formation.

Lifespan of RBCs

RBCs survive approximately 120 days; old RBCs are processed in the spleen, recycling nutrients.

Anemia

Defined as decreased RBC count and Hb leading to inadequate oxygen delivery.
Symptoms: Fatigue, weakness, rapid heart rate, shortness of breath, and pallor.
Classification: Normocytic, microcytic hypochromic, and macrocytic (megaloblastic) anemia based on the size and structure of RBCs.

Polycythemia

Elevated RBC count and hemoglobin; can be physiological (high altitudes) or pathological (due to lung/heart diseases).

Blood Groups

ABO System: Blood groups A, B, AB, and O based on the presence of specific antigens and corresponding antibodies.
- Group O: universal donor; Group AB: universal recipient.
Rh Factor: Rh-positive (85%) means presence of D antigen; Rh-negative (15%) lacks D antigen.
- Importance in erythroblastosis fetalis and blood transfusions.

Clinical Considerations

Antigen-antibody reactions are critical in blood transfusions to avoid hemolytic responses.
Cross-matching tests are essential before transfusions to ensure compatibility.

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Description

This quiz explores the vital fluid known as blood, its composition, and its crucial functions within the cardiovascular system. Learn about the components of blood, including plasma and cells, and how blood contributes to transport, defense, hemostasis, and homeostasis.