The plasma portion of human blood contains which of the following components? I. Proteins II. Salts III. Hormones

Introduction / Context:
Blood is a complex tissue consisting of cells suspended in a liquid matrix called plasma. Understanding the composition of plasma is important for topics such as transport of nutrients, waste products, hormones, and maintenance of osmotic balance. Exam questions often list several possible plasma constituents and ask you to identify which ones are actually present. This question focuses on proteins, salts, and hormones in plasma.

Given Data / Assumptions:

• The question lists three possible components of plasma: proteins, salts, and hormones.
• You must decide whether each is present or absent in normal plasma.
• We assume knowledge of basic blood composition.

Concept / Approach:
Plasma is the straw coloured liquid part of blood that remains when blood cells are removed. It is about ninety percent water and ten percent dissolved substances. Major dissolved components include plasma proteins such as albumin, globulins, and fibrinogen, inorganic salts such as sodium, potassium, chloride, and bicarbonate ions, and many organic molecules including glucose, amino acids, urea, and hormones. Hormones secreted by endocrine glands travel through the bloodstream, primarily in the plasma, to reach target tissues. Therefore, all three listed components, proteins, salts, and hormones, are present in plasma.

Step-by-Step Solution:
Step 1: Recall that plasma proteins include albumin for osmotic balance, globulins for immune functions, and fibrinogen for clotting. Step 2: Recognise that salts and ions dissolved in plasma help maintain osmotic balance, pH, and membrane potentials. Step 3: Understand that hormones are chemical messengers released into the blood to act on distant target organs, so they must be present in plasma. Step 4: Conclude that all three items, proteins, salts, and hormones, are found in the plasma portion of blood. Step 5: Choose the option that states all I, II and III.

Verification / Alternative check:
Physiology texts describe plasma composition tables listing proteins as major colloid components, electrolytes such as sodium and chloride with specific normal ranges, and hormones such as insulin and thyroid hormone present at lower concentrations. Laboratory tests for blood hormone levels analyze plasma or serum samples, further proving that hormones circulate in the liquid portion of blood. These sources confirm that all three listed substances are normal plasma constituents.

Why Other Options Are Wrong:

• Only I and II: This option incorrectly excludes hormones, even though hormones are known to circulate in plasma.
• Only I and III: This excludes salts, which are critical for osmotic balance and are always present in plasma.
• Only II and III: This excludes proteins, which are essential for osmotic pressure, transport, and clotting, and are abundant in plasma.

Common Pitfalls:
Some learners may mistakenly think of hormones as something separate from blood components because they are studied in endocrinology rather than in hematology. It is important to remember that hormones must travel from endocrine glands to target organs, and the main route is through the plasma. Others sometimes confuse plasma with serum. Serum is plasma without clotting factors, but it still contains proteins, salts, and hormones. Keeping these definitions clear helps in correctly answering composition questions.

Final Answer:
The plasma of human blood contains proteins, salts, and hormones, so all I, II and III are present.