Body Fluids and Its Circulation

Eosinophils constitute $2-3 \%$ of total WBCs. Hence its value is approximately 2 to $3 \%$ of $8000 / \mathrm{cu} \mathrm{mm}= 160-240 / \mathrm{cu} \mathrm{mm}$

Lymphocytes constitute $20-25 \%$ of total WBCs. Hence its value is approximately 20 to $25 \%$ of $8000 / \mathrm{cu} \mathrm{mm}=1600-2000 / \mathrm{cu} \mathrm{mm}$

(A) Incorrect → A special case of Rh incompatibility has been observed between the Rh-ve blood of a pregnant mother with $\mathrm{Rh}^{+\mathrm{ve}}$ blood of the foetus.

(B) Correct → Rh antigen is observed on the surface of RBCs of majority (nearly 80 percent) of humans.

(C) Correct → Before blood transfusion, Rh group should also be matched to avoid severe problems of destruction of RBCs.

(D) Correct → Rh incompatibility (Erythroblastosis foetalis) is observed when a pregnant mother is $\mathrm{Rh}^{-\mathrm{ve}}$ and the foetus is $\mathrm{Rh}^{+\mathrm{ve}}$.

(E) Incorrect → Erythroblastosis foetalis can be avoided by administering anti-Rh antibodies to the mother immediately after the delivery of the first child.

Thus, the incorrect statements are (A) and (E).

Fibrins are formed by the conversion of inactive fibrinogen in the plasma by the enzyme thrombin.

The number of action potentials generated by sino-atrial node (SAN) in a healthy human is 70-75 per minute.

The opening between the right atrium and the right ventricle is guarded by a valve formed of three muscular flaps or cusps, called the tricuspid valve.

A bicuspid/mitral valve guards the opening between the left atrium and the left ventricle.

The openings of the right and the left ventricles into the pulmonary artery and the aorta, respectively, are provided with the semilunar valves.

Frog's heart is a muscular structure with three chambers. It receives deoxygenated blood from body parts through the major veins called vena cava. Vena cava carries deoxygenated blood. Aorta and pulmonary vein carries oxygenated blood. Whereas, pulmonary artery will carry deoxygenated blood towards the lungs.

The blood group of a person determines which antigens are present on the surface of their red blood cells and which antibodies are present in their plasma. In this case, ARh$^-$ implies that the person has A antigens on the surface of the red blood cells and does not have the Rh antigen (Rh-negative). Therefore, the person with ARh$^-$ blood can only receive blood from donors whose blood does not contain any antigens that their immune system would recognize as foreign and mount a response against.

For a person with ARh$^-$ blood, suitable donors would have:

1. A antigen (to match the recipient's A antigen) and be Rh-negative.

2. O blood group (which has no A/B antigens) and be Rh-negative.

Let's go through the options:

• BRh$^-$: This blood group has B antigens, which would be recognized as foreign by the immune system of an A blood group recipient, hence it is not suitable.
• ABRh$^-$: This blood group has both A and B antigens, which would also be recognized as foreign due to the presence of the B antigen, making it unsuitable.
• ORh$^-$: This blood group has no A/B antigens, making it a universal donor for all ABO blood types and thus it is suitable for ARh$^-$ recipients.
• ARh$^-$: This blood group matches perfectly with the recipient since it has the same A antigen and is Rh-negative.
• ARh$^+$: This blood group has the A antigen but also has the Rh antigen (Rh-positive). The Rh antigen can trigger an immune response in someone who is Rh-negative, making this option unsuitable.

Therefore, the correct answer is:

Option D: C and D only

The correct answer is Option D: Vasopressin from Neurohypophysis. Here's why:

Diuresis refers to increased urine production. Let's break down how each option affects urine production:

Option A: Renin from JG cells via switching off the osmoreceptors

Renin, released from the juxtaglomerular (JG) cells, is part of the renin-angiotensin-aldosterone system (RAAS). RAAS primarily affects blood pressure and volume by:

• Increasing sodium reabsorption: This leads to water retention, thus increasing blood volume.
• Constricting blood vessels: This raises blood pressure.

While RAAS can indirectly influence urine production, it doesn't directly prevent diuresis. Also, osmoreceptors are stimulated by increased blood osmolarity, not switched off by renin.

Option B: ANF from atria of the heart

Atrial natriuretic factor (ANF) is a hormone released from the heart's atria in response to high blood pressure. ANF acts to:

• Decrease sodium reabsorption: This leads to increased urine output (diuresis) and lowers blood volume.
• Dilate blood vessels: This lowers blood pressure.

Therefore, ANF actually promotes diuresis, not prevents it.

Option C: Aldosterone from adrenal medulla

Aldosterone is a hormone secreted by the adrenal cortex, not the medulla. Its primary function is to increase sodium reabsorption in the kidneys, leading to water retention and increased blood volume. This effect is opposite to diuresis.

Option D: Vasopressin from Neurohypophysis

Vasopressin, also known as antidiuretic hormone (ADH), is released from the posterior pituitary gland (neurohypophysis). Vasopressin plays a crucial role in regulating water balance by:

• Increasing water reabsorption in the kidneys: This leads to concentrated urine and decreased urine output, preventing diuresis.

Vasopressin's action is the direct opposite of diuresis, making it the most effective in preventing excessive urine production.

In summary: Vasopressin (ADH) is the primary hormone responsible for preventing diuresis by increasing water reabsorption in the kidneys.

The correct answer is Option D: closure of the tricuspid and bicuspid valves. Here's why:

The "lub" sound of the heartbeat, known as the first heart sound (S1), is produced by the closure of the atrioventricular (AV) valves. These valves are the tricuspid valve (between the right atrium and right ventricle) and the bicuspid (mitral) valve (between the left atrium and left ventricle).

Here's a breakdown of the heart sounds and the events causing them:

• S1 (Lub): Closure of the AV valves (tricuspid and bicuspid). This occurs at the beginning of ventricular contraction (systole) when the ventricles are pushing blood out.
• S2 (Dub): Closure of the semilunar valves (pulmonary and aortic). This happens at the end of ventricular contraction when the ventricles are relaxing and filling with blood.

Let's look at why the other options are incorrect:

• Option A: closure of the semilunar valves: This causes the "dub" sound, not the "lub" sound.
• Option B: opening of tricuspid and bicuspid valves: This occurs during diastole (ventricular relaxation) and doesn't produce a significant heart sound.
• Option C: opening of the semilunar valves: This happens at the beginning of ventricular contraction and is silent.

In summary, the "lub" sound of the heart is generated by the closure of the tricuspid and bicuspid valves as the ventricles contract and push blood into the aorta and pulmonary arteries.

The electrical pathway for the conduction of an action potential through the heart is a precisely coordinated process, essential for maintaining the heart's rhythmic beating. To understand this conduction pathway, it’s important to know the roles of the specific components involved:

• SA node (Sinoatrial node): Often referred to as the pacemaker of the heart. It initiates the electrical impulse, causing the atria to contract.
• AV node (Atrioventricular node): Receives the impulse from the SA node and provides a slight delay, allowing the ventricles time to fill with blood before they contract.
• AV bundle (Bundle of His): Transfers the electrical impulse from the AV node to the bundle branches.
• Bundle branches: Conducts the impulses through the interventricular septum.
• Purkinje fibers: Distribute the electrical impulse throughout the ventricles, stimulating them to contract uniformly and powerfully.

The correct sequence for the pathway of an action potential through the heart follows a route designed to efficiently coordinate the heartbeat starting from the initiation of the action potential to the consequential contraction of the heart muscles. The sequence is:

1. SA node (E): The pacemaker where the electrical activity originates.
2. AV node (C): Where the impulse is delayed slightly.
3. AV bundle (A): Conducts the impulse from the AV node to the bundle branches.
4. Bundle branches (D): Leads the impulse to the Purkinje fibers.
5. Purkinje fibers (B): Distributes the impulse throughout the ventricles.

By examining the options provided with the above understanding:

• Option A: E-C-A-D-B
• Option B: A-E-C-B-D
• Option C: B-D-E-C-A
• Option D: E-A-D-B-C

Option A (E-C-A-D-B) correctly reflects the order in which the electrical impulse travels through the cardiac conduction system, beginning with the SA node and ending in the Purkinje fibers. Hence, Option A is the correct answer.

Option B:
$ A \rightarrow \text{(iii)}, B \rightarrow \text{(ii)}, C \rightarrow \text{(iv)}, D \rightarrow \text{(i)} $

A. P wave corresponds to (iii) Depolarisation of atria.

B. QRS complex corresponds to (ii) Depolarisation of ventricles.

C. T wave corresponds to (iv) Repolarisation of ventricles.

D. T-P gap corresponds to (i) Heart muscles are electrically silent.

An ECG (Electrocardiogram) is a test that measures the electrical activities of the heart. Each wave in an ECG represents a certain part of the heart's electrical activity:

1. P wave : This wave occurs prior to the contraction of the atria (atrial contraction). It represents the depolarization of the atria.


2. QRS complex : This is a series of three graph deflections seen on a typical electrocardiogram. It corresponds to the depolarization of the ventricles, which initiates the ventricular contraction.


3. T wave : The T wave represents the repolarization (or recovery) of the ventricles.

By matching these descriptions with the options provided :

(A) P-wave - Depolarisation of atria (III)

(B) QRS complex - Depolarisation of ventricles (I)

(C) T wave - Repolarisation of ventricles (IV)

(D) End of T wave - End of systole (II)

So, the correct answer seems to be Option D : A-(III), B-(I), C-(IV), D-(II)

This question asks to match types of white blood cells (List I) with their usual proportion in the blood (List II). The correct matchings are :

1. Eosinophils (A) - typically make up 1-6% of white blood cells, so the best match is (I) 6 - 8%


2. Lymphocytes (B) - typically make up 20-40% of white blood cells, but none of the options are in this range. However, since the other cells have more fitting matches, the remaining percentage (III) 20 - 25% would be the best fit.


3. Neutrophils (C) - these are the most common type of white blood cells, making up 50-70% of all white blood cells, so the best match is (IV) 60 - 65%


4. Monocytes (D) - typically make up 2-8% of white blood cells, so the best match is (II) 2 - 3%

So, the correct answer is Option C : A-(I), B-(III), C-(IV), D-(II)

The correct answer is Option B : B and C only.

Statement A is incorrect. Basophils are actually the least abundant cells of the total white blood cells (WBCs), not the most abundant.

Statement B is correct. Basophils do secrete histamine, serotonin, and heparin. Histamine and serotonin are involved in inflammatory response, while heparin is an anticoagulant.

Statement C is also correct. Basophils are involved in the inflammatory response. They release chemicals such as histamine and serotonin that dilate blood vessels and attract other white blood cells to the site of inflammation.

Statement D is incorrect. Basophils do not have a kidney-shaped nucleus. That description is more appropriate for monocytes, another type of white blood cell.

Statement E is incorrect. Basophils are not agranulocytes. They are granulocytes, a category of white blood cells characterized by the presence of granules in their cytoplasm. Agranulocytes, which lack visible cytoplasmic granules, include lymphocytes and monocytes.

Option (c) is the correct answer because hepatic portal system is a unique vascular connection between digestive tract and liver.

Option (a) is not correct because hepato-cystic system is part of biliary pathway where common hepatic duct joins cystic duct of gall bladder.

Option (b) is incorrect because hepato-pancreatic system is a part of biliary pathway where common bile duct fuses with pancreatic duct.

Option (d) is incorrect because renal portal system is a unique vascular connection between lower parts of the body and kidney.

Option (b) is the correct answer as a healthy adult man has, on an average, 5 millions to 5.5 millions of RBCs (erythrocytes) mm^–3 of blood.

Blood normally contains 1,50,000 – 3,50,000 platelets mm^–3.

Neutrophils form 60-65 percent of the total WBCs, monocytes form 6-8 percent of the total WBCs and eosinophils form 2-3 percent of the total WBCs. The total WBCs are approximately 6000-8000 mm^–3 of blood.

Thus, the formed elements in the decreasing order of their abundance in blood in humans: -

Erythrocytes – Platelets – Neutrophils – Monocytes – Eosinophils

Option (d) is the correct answer because coagulum or clot is formed mainly of a network of threads called fibrins. Hence, Statement I is incorrect.

RBCs are destroyed in the spleen so spleen is known as the graveyard of erythrocytes. Hence, Statement II is correct.

Option (c) is the correct answer because during joint diastole, blood moves freely from atrium to ventricle as atrioventricular valve remain open during joint diastole.

Option (d) is incorrect because decrease in ventricular pressure, during ventricular diastole closes semilunar valves to produce 'dub' heart sound.

Option (a) is incorrect because SA node generates action potential to stimulate atrial contraction.

Option (b) is incorrect because bicuspid and tricuspid valves open due to pressure exerted by blood present in atria and decrease in pressure in ventricles during ventricular diastole.

The function of Bowman’s capsule and glomerulus is filtration of blood. It is known as Glomerular filtration or ultrafiltration. Reabsorption of ions, hormones and water does not take place in it.

Both assertion and reason are true and reason is correct explanation of assertion.

Sino-Atrial node (SA node) is the natural pacemaker of heart producing electrical impulses for heart contraction. Any kind of malfunctioning in SA node leads to the disturbance of heart rate and normal heart functioning.