The WBC count is 8000/cu.mm. How many eosinophils and lymphocytes would be in the same blood sample approximately?

160 – 240/cu.mm and 1600 – 2000/cu.mm, respectively

100 – 120/cu.mm and 160 – 200/cu.mm, respectively

300 – 500/cu.mm and 500 – 700/cu.mm, respectively

300 – 500/cu.mm and 1200 – 1500/cu.mm, respectively

Match the following: (a) Eosinophils (i) Immune response (b) Basophils (ii) Phagocytosis (c) Neutrophils (iii) Release histaminase (d) Lymphocytes (iv) Release histamine

(D) (a-iii) (b-iv) (c-ii) (d-i)

(A) (a-iv) (b-i) (c-ii) (d-iii)

(B) (a-i) (b-ii) (c-iv) (d-iii)

(C) (a-ii) (b-i) (c-iii) (d-iv)

Formed Elements

உருவான கூறுகள்

NCERT Class 11 · Body Fluids and Circulation · 5 NEET questions

Blood is not just a fluid; it is a cellular suspension. If you confuse plasma volume with formed elements, you lose 4 marks. Remember, formed elements occupy exactly 45% of blood volume.

The idea

Formed elements consist of erythrocytes, leucocytes, and platelets. Erythrocytes are the most abundant, facilitating gas transport via hemoglobin. Leucocytes provide the immune response, while platelets are essential for the coagulation cascade. These three components are suspended in the plasma matrix.

Why it matters

These specialized cells are required for oxygen delivery, defense against pathogens, and preventing blood loss through clotting.

NEET lens

NEET focuses on the percentage composition and the specific functions of each cell type. Expect matching-type questions linking cell types to their physiological roles. Do not confuse the granular and agranular classification of WBCs; that is a high-frequency trap.

Clinical significance

A drop in erythrocyte count leads to anemia, reducing oxygen-carrying capacity. Conversely, a deficiency in platelets causes thrombocytopenia, leading to uncontrolled bleeding. Homeostasis fails when these cellular proportions are disrupted.

Introduction

Formed elements are the cellular components of blood: Red Blood Cells (RBCs/erythrocytes), White Blood Cells (WBCs/leukocytes), and Platelets (thrombocytes) — together making up ~45% of blood volume (hematocrit).

Core concept

RBCs (Erythrocytes): 5 million/mm³ (male), 4.5 million (female). Biconcave disc. No nucleus (mature mammalian RBCs). Lifespan: 120 days. Destroyed in spleen ('graveyard of RBCs'). Contain hemoglobin (O₂ transport). WBCs (Leukocytes): 6,000-8,000/mm³. Two types: Granulocytes (neutrophils, eosinophils, basophils) and Agranulocytes (lymphocytes, monocytes). Platelets (Thrombocytes): 1.5-3.5 lakh/mm³. Cell fragments from megakaryocytes. Lifespan: 5-10 days. Clotting function. All formed elements produced in: Red bone marrow (haematopoiesis).

Go deeper

RBC biconcave shape: increases surface area-to-volume ratio → more hemoglobin exposed → faster O₂ loading/unloading. No nucleus = more space for hemoglobin (~280 million Hb molecules per RBC). No mitochondria → use glycolysis only → don't consume the O₂ they carry.

From Class 10

Blood is not just a liquid — it contains solid cellular components called formed elements. These are the red blood cells, white blood cells, and platelets.