Blood Composition and Functions Quiz

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Questions and Answers

What is the life span of erythrocytes before they are destroyed?

About 120 days (correct)

About 90 days

About 150 days

About 60 days

Which condition is characterized by an increase in the RBC count?

Polycythaemia (correct)

Oligocythaemia

Leukopenia

Anaemia

Which of the following statements about leukocytes is true?

Leukocytes can have a life span of hours to days (correct)

Leukocytes have no nuclei

Leukocytes are smaller and more numerous than RBCs

Leukocytes transport oxygen and carbon dioxide

What feature of RBCs helps them increase the surface area for gas exchange?

Biconcave shape Signup and view all the answers

Which type of leukocyte is primarily involved in cellular immunity?

T cells Signup and view all the answers

What is the total leukocytic count range in blood?

4,000 – 11,000 /mm3 Signup and view all the answers

Which characteristic is typical of mature neutrophils?

Segmentation into 2-5 lobes Signup and view all the answers

What term describes a decrease in hemoglobin levels in the blood?

Anaemia Signup and view all the answers

What organelle is primarily responsible for the storage of calcium in platelets?

Dense tubular system Signup and view all the answers

Which type of granule in platelets contains ADP and ATP?

Delta granules Signup and view all the answers

What is the primary function of platelets?

Prevent bleeding from injured blood vessels Signup and view all the answers

In platelets, which structure is involved in adhesion due to its glycocalyx?

Cell membrane Signup and view all the answers

What is the lifespan of a platelet in circulation?

9-10 days Signup and view all the answers

What is the primary function of neutrophils in the immune response?

Phagocytosis and defense against bacterial invasion Signup and view all the answers

What percentage of white blood cells do eosinophils represent?

2-4% Signup and view all the answers

What is a key characteristic of the nucleus of eosinophils?

Bilobed connected by thick chromatin thread Signup and view all the answers

Which granules in basophils contain histamine?

Basophilic specific granules Signup and view all the answers

What is a potential consequence of neutrophilia?

Acute bacterial infections Signup and view all the answers

What role do eosinophils play in allergic reactions?

Phagocytosis of antigen-antibody complexes Signup and view all the answers

Which enzyme is associated with eosinophils and is involved in degrading histamine?

Histaminase Signup and view all the answers

What happens to the lifespan of eosinophils in connective tissue?

Less than 2 weeks Signup and view all the answers

Which type of lymphocyte is primarily responsible for humoral immunity?

B-lymphocytes Signup and view all the answers

What is the average lifespan of basophils?

1-2 days Signup and view all the answers

Which of the following types of lymphocyte is the most abundant?

T-lymphocytes Signup and view all the answers

What is a key feature of monocytes when observed under light microscopy?

Frosted-glass appearance Signup and view all the answers

What is the function of T-helper cells?

To enhance the response of other immune cells Signup and view all the answers

Which of the following indicates a condition with elevated lymphocyte levels?

Influenza infection Signup and view all the answers

What is the origin of platelets in the bloodstream?

Megakaryocytes Signup and view all the answers

Which cell type is primarily involved in cellular (cell-mediated) immunity?

T-lymphocytes Signup and view all the answers

What is the primary component of blood that makes up 55% of its volume?

Plasma Signup and view all the answers

Which blood element is characterized as a non-nucleated, biconcave disc?

Erythrocytes Signup and view all the answers

What is the pH level of blood in a healthy adult?

7.4 Signup and view all the answers

Which type of stain is commonly used to prepare a peripheral blood film?

Romanovsky stain Signup and view all the answers

What structural characteristic helps maintain the shape of erythrocytes?

Membrane proteins Signup and view all the answers

What is the diameter range for healthy erythrocytes?

6-9 µm Signup and view all the answers

Which blood element is primarily responsible for the immune response?

Leukocytes Signup and view all the answers

What condition is characterized by the variation in the diameters of red blood cells?

Anisocytosis Signup and view all the answers

Study Notes

Blood

Blood is a red, viscous, slightly alkaline fluid (pH 7.4).
The total volume of blood in an adult is about 6 liters.
It circulates in a closed system of tubes (blood vessels) propelled by the pumping action of the heart.
Blood is considered a type of connective tissue.
Blood comprises formed elements (cells) suspended in plasma.

Peripheral Blood Film

Blood film is prepared, air dried, and stained with Romanovsky stains:
- A mixture of eosin (acidic), methylene blue (basic), and related azures (basic).

Components of Blood

Plasma: 55% of blood volume.
- Water - 90-91%
- Plasma proteins - 7-8% (albumin, globulins, and fibrinogen)
- Other solutes - 1-2% (electrolytes, urea, uric acid, glucose, lipids, amino acids, hormones, and blood gases)
Formed elements: 45% of blood volume.
- Erythrocytes (RBCs)
- Leukocytes (WBCs)
- Thrombocytes (platelets)

Erythrocytes (RBCs)

Non-nucleated, biconcave disc shape.
Size – 6-9 µm in diameter.
- Microcyte: Smaller than normal RBC.
- Normocyte: Normal size RBC.
- Macrocyte: Larger than normal RBC.
Color:
- Fresh RBC is greenish yellow with a pale central area due to hemoglobin (Hb) content.
- Stained blood film may show:
  - Normochromic: Pink, with a pale center when stained with Leishman.
  - Hyperchromic: Deeply stained with more Hb content
  - Hypochromic: Pale stained with less Hb content.
Number:
- Adult male: 4.3–5.7 million/ml3
- Adult female: 3.9–5 million/ml3
Life span:
- About 120 days.
- They are destroyed by macrophages in the liver and spleen.
- Hb is broken into globin and hematin.
Function:
- Transporting O2 and CO2 to and from the body's tissues.
Structure-function adaptation of RBCs:
- Biconcave shape to increase surface area for gas exchange.
- Highly selective cell membrane for gas exchange.
- Highly elastic properties and stability of the cell membrane.
- Absence of the nucleus and organelles give more space for Hb.

Leukocytes (WBCs)

All are true cells with nuclei and organelles.
Larger and much less numerous than RBCs (~700:1 ratio).
Short life span (hours to days).
Cytoplasm: Granular and Agranular (Non-granular).
Function in immunity: Both cellular (T cells and phagocytic WBCs) and humoral (B cells).
Total leukocytic count: 4,000–11,000/mm3
Leukocytosis: Increase in WBC count.
- Physiological (normal)
- Pathological (abnormal)
Leukopenia: Decrease in WBC count

Granular Leukocytes

Neutrophils

Represent 60–75% of WBCs.
Size: 10–12 µm in diameter.
Nucleus:
- Immature neutrophil (band form)
- Mature neutrophil: Single but segmented (multilobed), formed of 2–5 lobes interconnected by fine chromatin threads (polymorphonuclear leukocytes).
Cytoplasm:
- By LM: Reddish purple.
- By EM: Contains 3 types of granules:
  - Specific granules (80%): Small, contain alkaline phosphatase, collagenase, and lactoferrin (bacteriostatic).
  - Azurophilic granules (20%): Large, are lysosomes, contain hydrolytic enzymes, proteolytic and lipolytic enzymes, and peroxidase.
  - Tertiary granules: Contain collagenases and gelatinases to facilitate migration through the connective tissue.
Function:
- First line of defense against bacterial invasion (migration and diapedesis).
- Phagocytosis (microphage).
- Dead neutrophils are the main cellular constituent in pus.
- Produce pyrogens that cause fever.
- Attraction of monocytes.
- Stimulation of bone marrow to form new neutrophils.
Life span: About 4 days.
Neutrophilia: In acute bacterial infections as acute tonsillitis.
Neutropenia: In typhoid fever, influenza, and measles.

Eosinophils

Represent 2–4% of WBCs.
Size: 10–12 µm in diameter.
Nucleus: Bilobed connected by thick chromatin thread.
Cytoplasm:
- By LM: Large specific granules.
- By EM: Large oval with a crystalloid body (major basic protein) and a less electron-dense matrix (histaminase, eosinophilic peroxidase).
Function:
- Important role in allergic reactions:
  - Phagocytosis of antigen-antibody complexes.
  - Produce histaminase (degrade histamine and SRS-A).
- Involved in the destruction of parasites.
Life span:
- In blood: Few days.
- In connective tissue: < 2 weeks.
Eosinophilia: In allergy and parasitic infestation.
Eosinopenia: During cortisone treatment.

Basophils

Represent less than 1% of WBCs.
Size: 10–12 µm in diameter.
Nucleus: S-shaped or irregular in shape (obscured).
Cytoplasm:
- By LM: Large basophilic specific granules masking the nucleus.
- By EM: Specific spherical homogenous electron-dense granules (heparin, histamine, and ECF) and few azurophilic granules.
Function:
- Similar to mast cells, basophils have receptors for IgE.
Life span: 1–2 days.
Basophilia: In allergy and liver cirrhosis.

Agranular Leukocytes

Lymphocytes

Represent 20–30% of WBCs.
Rounded cells with a round nucleus and very little cytoplasm.
Types of lymphocytes (according to size):
- 92%: Small lymphocytes (6–8 µm in diameter).
- Medium-sized lymphocytes (10–15 µm in diameter).
- Large lymphocytes (18–30 µm in diameter).
Types of lymphocytes (according to function):
- B-lymphocytes (15%): Arise and differentiate in the bone marrow. Responsible for humoral immunity (secretion of Abs). They must differentiate in tissue to plasma cells producing antibodies.
- T-lymphocytes (80%): Arise in bone marrow and differentiate in the thymus. Responsible for cellular (cell-mediated) immunity. Types: T-helper cells (CD4+) and T-cytotoxic cells (CD8+).
- Null (N) or Natural Killer (NK) cells (5%): Function in cell-mediated cytotoxicity.
Small Lymphocytes:
- Nucleus: Large, central, rounded, and condensed.
- Cytoplasm: Scanty (forming a narrow rim around the nucleus), lightly basophilic, and non-granular. Contains numerous free ribosomes and few organelles.
Medium Lymphocytes:
- Nucleus: Larger, indented, and lightly stained.
- Cytoplasm: Large number of mitochondria, abundant rER, well-developed Golgi complex, and non-granular.
Lymphocytosis: In T.B., viral infection (influenza), and lymphoma.
Lymphopenia: In AIDS and aplastic anemia.

Monocytes

Represent 3–8% of WBCs
The largest of blood cells.
Size: 12-20 µm in diameter.
Nucleus: Large and kidney shaped.
Cytoplasm:
- By LM: Faint greyish blue (frosted-glass appearance).
- By EM: Numerous lysosomes and pseudopodia.
Life span:
- About 3 in peripheral blood and 3 months in connective tissue (macrophages).
Function:
- Highly phagocytic cells.
- They migrate to connective tissue and differentiate into macrophages.
Monocytosis: In malaria and T.B.

Platelets

Origin: From megakaryocytes present in the bone marrow.
Size: 2–4 µm in diameter.
Shape: Rounded to oval, non-nucleated cell fragments covered by a cell membrane.
Number: 250,000–400,000 /mm3
Life span: Stay in blood for about 9–10 days.
Cytoplasm:
- By LM: Each has a central granular region (granulomere) and a peripheral clear region (hyalomere).
- By EM:
  - Cell membrane: Covered by glycocalyx involved in platelets adhesion.
  - Hyalomere:
    - Microtubules.
    - Actin and myosin.
    - Tubules in the hyalomere:
      - Surface connecting canalicular system.
      - Dense tubular system: Narrow regular tubes (Ca storage) in cytoplasm.
  - Granulomere:
    - Mitochondria, ribosomes, glycogen, and 3 types of granules.
      - Alpha (α) granules: Contain fibrinogen, coagulation factors, and platelet-derived growth factor.
      - Delta (dense bodies): Contain Ca, ADP & ATP, and serotonin.
      - Lambda (175–250 nm): Are lysosomes (contain hydrolyti enzymes).
Function: Prevent bleeding from injured blood vessels.

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Description

Test your knowledge on the composition and functions of blood. This quiz covers blood components, peripheral blood films, and the role of erythrocytes, leukocytes, and thrombocytes. Perfect for students studying human biology or related subjects.