Composition and Functions of Blood — MCQs

10 questions

The body fluid compartments of a patient were measured, showing the following ion concentrations: - Sodium (Na): $10 \mathrm{mEq} / \mathrm{L}$ - Potassium (K): $140 \mathrm{mEq} / \mathrm{L}$ - Chloride (Cl): $15 \mathrm{mEq} / \mathrm{L}$ Based on these values, which fluid compartment is being described?

For doing ABG, which of the following is used?

What is the freezing point of normal human plasma?

Which of the following is not a hemoprotein?

What is the primary stimulus for erythropoietin production?

The acute inflammatory response is predominantly mediated by which type of immune cells?

Which non-selective beta-blocker has sympathomimetic activity?

Estimation of the blood sugar is relevant in all except –

Chyluria is due to which of the following?

Q10

Which of the following statements about sickle cell anemia is false?

Composition and Functions of Blood Indian Medical PG Practice Questions and MCQs

Question 1: The body fluid compartments of a patient were measured, showing the following ion concentrations: - Sodium (Na): $10 \mathrm{mEq} / \mathrm{L}$ - Potassium (K): $140 \mathrm{mEq} / \mathrm{L}$ - Chloride (Cl): $15 \mathrm{mEq} / \mathrm{L}$ Based on these values, which fluid compartment is being described?

A. Plasma
B. ICF (Correct Answer)
C. Interstitial fluid
D. ECF

Explanation: ***ICF*** - The measured ion concentrations, especially **high potassium (140 mEq/L)** and **low sodium (10 mEq/L)**, are characteristic of the **intracellular fluid (ICF)**, where potassium is the primary cation and sodium is kept low by the Na+/K+-ATPase pump. - **Chloride levels (15 mEq/L)** are also significantly lower in the ICF compared to extracellular fluids. *Plasma* - Plasma typically has **high sodium (around 140 mEq/L)** and **low potassium (around 4 mEq/L)**, which contradicts the given measurements. - Chloride levels in plasma are usually much higher, around **100-105 mEq/L**. *Interstitial fluid* - Interstitial fluid has an electrolyte composition very similar to plasma, with **high sodium** and **low potassium**, differing mainly in protein content. - This composition is not consistent with the given measurements. *ECF* - The ECF (extracellular fluid), which includes both plasma and interstitial fluid, is characterized by **high sodium** and **low potassium**. - The given ion concentrations, particularly the very **high potassium** and **low sodium**, are directly opposite to the typical ECF profile.

Question 2: For doing ABG, which of the following is used?

A. RBC
B. Serum
C. Whole blood (Correct Answer)
D. Plasma

Explanation: ***Whole blood*** - **Arterial blood gases (ABG)** analyze the gaseous components and acid-base balance directly in the blood as it circulates, so **whole blood** is required. [3] - The sample is typically drawn from an **artery** and processed immediately to prevent changes in gas levels due to metabolism. [3] *RBC* - **Red blood cells (RBCs)** are only one component of blood; analyzing them alone would not provide the full picture of **gas exchange** and **acid-base status**. [1], [2] - While RBCs carry oxygen and carbon dioxide, the ABG test measures these gases dissolved in the **plasma** and within the RBCs. [2] *Serum* - **Serum** is the liquid portion of blood that remains after coagulation, meaning **clotting factors** and cells have been removed. - This process significantly alters the **gas concentrations** and **pH**, making it unsuitable for ABG analysis. *Plasma* - **Plasma** is the liquid component of blood, but collecting it requires the removal of **red blood cells** and other cellular components. [1] - ABG analysis relies on the interplay of gases in both the **cellular** and **liquid** phases of blood for accurate results. [3]

Question 3: What is the freezing point of normal human plasma?

A. 0° C
B. –0.54° C (Correct Answer)
C. –1.54° C
D. 4° C

Explanation: ***–0.54° C*** - The **freezing point depression** of normal human plasma is approximately **–0.54° C**, which is a key physical property used to assess plasma osmolality. - This specific value reflects the **total concentration of solutes** (like electrolytes, glucose, and urea) in the plasma. *0° C* - This is the freezing point of **pure water**, which does not account for the dissolved solutes in human plasma. - Due to the presence of solutes, the freezing point of plasma is **depressed below 0° C**. *–1.54° C* - This value represents a significantly **lower freezing point depression**, suggesting a much higher concentration of solutes than found in normal human plasma. - Such a low freezing point would indicate a state of **severe hyperosmolality**. *4° C* - This temperature is above the freezing point of water and human plasma, typically used for **refrigeration** rather than indicating freezing point. - Plasma would be in a **liquid state** at this temperature.

Question 4: Which of the following is not a hemoprotein?

A. Myoglobin
B. Elastin (Correct Answer)
C. Cytochrome P450
D. Catalase

Explanation: ***Correct: Elastin*** - **Elastin** is a structural protein primarily found in **connective tissues** that provides elasticity to organs and tissues (skin, blood vessels, lungs) - It does NOT contain a **heme group** and is therefore not classified as a hemoprotein - Functions purely as a structural component without any prosthetic groups *Incorrect: Myoglobin* - **Myoglobin** is an iron- and oxygen-binding protein found in muscle tissue - Contains a single **heme group** with an iron atom, making it a quintessential hemoprotein - Functions in oxygen storage and delivery in muscle cells *Incorrect: Cytochrome P450* - **Cytochrome P450** enzymes are a superfamily of hemoproteins containing a **heme prosthetic group** - The heme iron is crucial for their role in **drug metabolism** and detoxification - Involved in metabolism of endogenous and exogenous compounds in the liver *Incorrect: Catalase* - **Catalase** is an enzyme that catalyzes decomposition of hydrogen peroxide (H₂O₂) into water and oxygen - Contains a **heme prosthetic group** with an **iron atom** essential for its enzymatic activity - One of the most efficient enzymes, protecting cells from oxidative damage

Question 5: What is the primary stimulus for erythropoietin production?

A. Increased temperature
B. Decreased blood pressure
C. Decreased plasma proteins
D. Tissue hypoxia (Correct Answer)

Explanation: ***Tissue hypoxia*** - Erythropoietin (EPO) production is primarily stimulated by sensing **low oxygen levels** in the kidneys. - This response is crucial for maintaining adequate oxygen delivery to tissues by increasing **red blood cell mass**. *Increased temperature* - An increase in body temperature is a stimulus for processes like **sweating** and **vasodilation**, to regulate body temperature. - It does not directly affect erythropoietin production or red blood cell synthesis. *Decreased blood pressure* - A decrease in blood pressure primarily stimulates the **renin-angiotensin-aldosterone system** and the release of **ADH** to regulate blood volume and pressure. - It does not directly cause an increase in erythropoietin release as its primary function is not related to oxygen sensing. *Decreased plasma proteins* - A decrease in plasma proteins primarily affects **oncotic pressure** and can lead to edema. - It is not a direct stimulus for erythropoietin production.

Question 6: The acute inflammatory response is predominantly mediated by which type of immune cells?

A. T lymphocytes
B. Neutrophils (Correct Answer)
C. Both B and T lymphocytes
D. B lymphocytes

Explanation: ***Neutrophils*** - **Neutrophils** are the **primary mediators** of the **acute inflammatory response**, being the first immune cells recruited to sites of injury or infection (usually within minutes to hours) [1], [3]. - They are **innate immune cells** that perform phagocytosis, release antimicrobial substances, and form neutrophil extracellular traps (NETs) to combat pathogens [1]. - Neutrophils constitute **50-70% of circulating leukocytes** and are the hallmark cells found in acute inflammation [3]. *T lymphocytes* - **T lymphocytes** are central to **cell-mediated immunity** in the adaptive immune response, requiring several days for activation and clonal expansion [2]. - They recognize specific antigens through TCRs and are not involved in the immediate, non-specific phase of acute inflammation. - T cells play roles in **chronic inflammation** and coordinating adaptive immunity, not acute responses. *B lymphocytes* - **B lymphocytes** mediate **humoral immunity** by producing antibodies during the adaptive immune response [1]. - Their activation, differentiation into plasma cells, and antibody production take days to weeks, making them irrelevant to the rapid acute inflammatory response. - B cells are not recruited to acute inflammatory sites in the initial phase. *Both B and T lymphocytes* - While both are critical for **adaptive immunity** and host defense, neither B nor T lymphocytes are primary mediators of acute inflammation [4]. - The acute inflammatory response relies on **innate immune cells** (neutrophils, macrophages, mast cells) for immediate, non-specific protection before adaptive immunity develops [4].

Question 7: Which non-selective beta-blocker has sympathomimetic activity?

A. Nadolol
B. Pindolol (Correct Answer)
C. Acebutalol
D. Metoprolol

Explanation: ***Pindolol*** - **Pindolol** is a **non-selective beta-blocker** that exhibits **intrinsic sympathomimetic activity (ISA)**, meaning it acts as a partial agonist at beta-adrenergic receptors. - Due to ISA, it causes less reduction in resting heart rate and cardiac output compared to beta-blockers without ISA. *Acebutalol* - **Acebutalol** is a **beta-1 selective blocker** (cardioselective) that possesses **intrinsic sympathomimetic activity (ISA)**. - While it has ISA, it is not a non-selective beta-blocker, making it an incorrect answer for this question. *Nadolol* - **Nadolol** is a **non-selective beta-blocker** that does **not** have intrinsic sympathomimetic activity (ISA). - It primarily acts as a pure antagonist at both beta-1 and beta-2 adrenergic receptors. *Metoprolol* - **Metoprolol** is a **beta-1 selective blocker** (cardioselective) and does **not** possess intrinsic sympathomimetic activity (ISA). - Its primary action is blockade of cardiac beta-1 receptors.

Question 8: Estimation of the blood sugar is relevant in all except –

A. Large for date baby
B. Birth asphyxia
C. Rh Incompatibility
D. Baby of hypothyroid mother (Correct Answer)

Explanation: ***Baby of hypothyroid mother*** - While maternal hypothyroidism can affect fetal development and lead to various complications, it does not directly cause **neonatal hypoglycemia** or **hyperglycemia**, making routine blood sugar monitoring less critical unless other risk factors are present. - The primary concerns for a baby born to a hypothyroid mother are related to thyroid function itself, such as **congenital hypothyroidism**, not blood glucose dysregulation. *Large for date baby* - **Macrosomic infants**, especially those born to mothers with gestational diabetes, are at increased risk for **hypoglycemia** due to chronic fetal hyperinsulinemia. - Close monitoring of blood glucose levels is essential to prevent neurological damage from sustained low sugar. *Birth asphyxia* - Infants who experience **birth asphyxia** are under significant stress, which can deplete their glycogen stores and impair gluconeogenesis, leading to **hypoglycemia**. - Monitoring blood glucose is a critical component of their post-resuscitation care and management. *Rh Incompatibility* - Severe **Rh incompatibility** can lead to **hydrops fetalis** and other complications, including liver dysfunction and extramedullary hematopoiesis, which can impair glucose regulation. - These infants are at risk for both **hypoglycemia** due to increased metabolic demand and **hyperglycemia** secondary to stress and liver involvement, necessitating blood sugar monitoring.

Question 9: Chyluria is due to which of the following?

A. Filaria (Correct Answer)
B. Carcinoma
C. Tuberculosis
D. Malaria

Explanation: ***Filaria*** - **Filarial infections**, specifically **lymphatic filariasis** caused by parasites like *Wuchereria bancrofti* and *Brugia malayi*, are the most common cause of chyluria worldwide. - These parasites obstruct lymphatic vessels, leading to leakage of **lymphatic fluid (chyle)** into the urinary tract. *Carcinoma* - While tumors can cause lymphatic obstruction, chyluria due to carcinoma is **less common** than filariasis and typically associated with advanced malignancy directly invading or compressing lymphatic drainage. - The primary presentation would likely involve symptoms related to the **underlying cancer**, rather than chyluria as the initial or sole symptom. *Tuberculosis* - **Tuberculosis (TB)** can affect various organ systems, including the lymphatic system, but it is a **rare cause of chyluria**. - If TB were to cause chyluria, it would often be part of a broader presentation of **disseminated TB** or **tuberculous lymphadenitis** involving significant lymphatic obstruction. *Malaria* - **Malaria** is a parasitic disease caused by *Plasmodium* species transmitted by mosquitoes, primarily affecting red blood cells and the liver. - It does **not directly cause chyluria** and is not associated with lymphatic obstruction or leakage of chyle into the urine.

Question 10: Which of the following statements about sickle cell anemia is false?

A. Sickle cells are present in sickle cell anemia.
B. Target cells are commonly seen in sickle cell anemia.
C. Ringed sideroblasts are associated with sickle cell anemia. (Correct Answer)
D. Howell Jolly bodies can be found in sickle cell anemia.

Explanation: ***Ringed sideroblast*** - **Ringed sideroblasts** are not typically associated with sickle cell anemia; they are indicative of disorders like **sideroblastic anemia**. - In sickle cell anemia, the primary findings include **hemolysis** and ineffective erythropoiesis, not ringed sideroblasts [3]. *Howell jolly bodies* - These bodies are remnants of nuclear material and can be found in individuals with **spleen dysfunction**, which can occur in sickle cell anemia [1]. - They are actually a common finding due to **hyposplenism** or **asplenia** in patients with sickle cell disease [2]. *Sickle cells* - The presence of **sickle-shaped red blood cells** is a hallmark of sickle cell anemia, caused by the mutation in the **beta-globin chain** [3]. - These sickle cells are responsible for the characteristic complications of the disease, such as **vaso-occlusive crises** [1][3]. *Target cells* - Target cells, or **codocytes**, are often seen in disorders like **thalassemia** and liver disease, and can also be present in sickle cell anemia. - They are formed due to an increase in the **surface area to volume ratio** of red blood cells, often secondary to **membrane abnormalities** seen in sickle cell changes [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 644-646. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 570-571. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 598-599.

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