Body Fluids — Revision Notes

⚡ 30-Second Revision

Blood: — Plasma (55%) + Formed Elements (45%).\n- Plasma: 92% water, 8% proteins (Albumin - osmotic balance, Globulins - immunity, Fibrinogen - clotting).\n- Formed Elements:\

\quad - RBCs (Erythrocytes): $5-5.5 \times 10^6/mm^3$, biconcave, anucleated, hemoglobin, 120-day lifespan.\ \quad - WBCs (Leukocytes): $6000-8000/mm^3$, immune function. Granulocytes (Neutrophils - phagocytic, most abundant; Eosinophils - allergy/parasites; Basophils - inflammation) & Agranulocytes (Lymphocytes - specific immunity; Monocytes - macrophages).

\ \quad - Platelets (Thrombocytes): $1.5-3.5 \times 10^5/mm^3$, clotting.\ - Blood Groups (ABO): Antigens on RBCs, Antibodies in plasma. O is universal donor, AB is universal recipient.\ - Rh Factor: D antigen.

Rh- mother + Rh+ fetus = erythroblastosis fetalis.\ - Coagulation: Platelets \rightarrow Prothrombinase \rightarrow Prothrombin \xrightarrow{\text{Thrombin}} Thrombin \rightarrow Fibrinogen \xrightarrow{\text{Thrombin}} Fibrin clot.

\ - Lymph: Interstitial fluid + Lymphocytes. Low protein, no RBCs. Functions: fluid return, fat absorption, immunity.

2-Minute Revision

Body fluids are crucial for maintaining homeostasis. The main fluids are blood, lymph, and interstitial fluid. Blood, a specialized connective tissue, consists of plasma (55%) and formed elements (45%).

Plasma is mostly water, with proteins like albumin (osmotic balance), globulins (immunity), and fibrinogen (clotting). Formed elements include RBCs (oxygen transport, biconcave, anucleated, 120-day lifespan), WBCs (immune defense, classified into granulocytes and agranulocytes, with neutrophils being most abundant and phagocytic), and platelets (blood clotting).

Blood grouping (ABO and Rh) is based on antigens on RBCs; Type O is a universal donor, Type AB is a universal recipient. Rh incompatibility can cause erythroblastosis fetalis. Blood clotting is a cascade where thrombin converts fibrinogen to fibrin.

Lymph is interstitial fluid that enters lymphatic vessels, containing lymphocytes but low protein and no RBCs. It returns fluid to blood, absorbs fats, and plays a key immune role via lymph nodes.

5-Minute Revision

Body fluids are the internal environment of the body, essential for homeostasis. The three main types are blood, lymph, and interstitial fluid, each with distinct compositions and functions.\n\nBlood is a fluid connective tissue, making up about 7-8% of body weight.

It has two main components:\ 1. Plasma (approx. 55%): The liquid matrix, 90-92% water. Contains plasma proteins (albumin for osmotic pressure, globulins for immunity, fibrinogen for clotting), electrolytes, nutrients, hormones, and waste products.

Serum is plasma minus clotting factors.\ 2. Formed Elements (approx. 45%):\ * Erythrocytes (RBCs): Most numerous ($5-5.5 \times 10^6/mm^3$). Biconcave, anucleated (in mammals), contain hemoglobin for oxygen transport.

Lifespan ~120 days.\ * Leukocytes (WBCs): $6000-8000/mm^3$. Immune cells. Granulocytes (Neutrophils - most abundant, phagocytic; Eosinophils - allergy/parasites; Basophils - inflammation) and Agranulocytes (Lymphocytes - specific immunity; Monocytes - differentiate into macrophages).

\ * Platelets (Thrombocytes): $1.5-3.5 \times 10^5/mm^3$. Cell fragments for blood clotting.\ Blood Groups: ABO system (A, B, AB, O based on antigens on RBCs and antibodies in plasma). Rh system (Rh antigen, D antigen).

Rh incompatibility (e.g., Rh- mother with Rh+ fetus) can lead to erythroblastosis fetalis.\ Blood Coagulation (Hemostasis): A cascade involving platelets and clotting factors. Injury exposes collagen, platelets form a plug.

Prothrombinase converts prothrombin to thrombin. Thrombin then converts soluble fibrinogen into insoluble fibrin threads, forming the clot. Calcium ions and Vitamin K are essential.\ \nLymph is a colorless fluid formed when interstitial fluid enters lymphatic capillaries.

It is similar to plasma but has significantly lower protein content and contains abundant lymphocytes. It lacks RBCs and platelets. Functions include returning excess interstitial fluid and proteins to the blood, absorbing digested fats (via lacteals), and playing a crucial role in immunity by transporting lymphocytes and filtering pathogens in lymph nodes.

\ \nInterstitial Fluid is the fluid that bathes the cells, acting as a medium for exchange between blood and cells. It's formed by filtration from blood plasma and has a composition similar to plasma but without large proteins and formed elements.

\ \nExample: If a person has Type O blood, they have no A or B antigens on their RBCs but have both anti-A and anti-B antibodies in their plasma. They can donate to any ABO blood type (universal donor) but can only receive blood from other Type O individuals to avoid agglutination reactions.

Prelims Revision Notes

1
Blood Composition: — Blood is a fluid connective tissue. Average volume is $5-5.5$ liters. Composed of Plasma (approx. 55%) and Formed Elements (approx. 45%).\

2. Plasma: Straw-colored, viscous fluid. 90-92% water. Contains 6-8% plasma proteins: Albumin (most abundant, maintains osmotic pressure), Globulins (defense, transport), Fibrinogen (blood clotting).

Also contains glucose, amino acids, lipids, electrolytes, hormones, waste products. Serum = Plasma - Clotting Factors.\ 3. Formed Elements (Hematopoiesis in bone marrow):\ * Erythrocytes (RBCs): $5-5.

5 \times 10^6/mm^3$. Biconcave, anucleated (in mammals), contain hemoglobin. Lifespan ~120 days. Destroyed in spleen (graveyard of RBCs).\ * **Leukocytes (WBCs):**$6000-8000/mm^3$. Nucleated, short-lived.

Classified into:\ * Granulocytes: Neutrophils (60-65%, most abundant, phagocytic), Eosinophils (2-3%, allergy, parasitic infections), Basophils (0.5-1%, release histamine, serotonin, heparin - inflammatory response).

\ * Agranulocytes: Lymphocytes (20-25%, B and T cells, specific immunity), Monocytes (6-8%, phagocytic, differentiate into macrophages).\ * Platelets (Thrombocytes): $1.5-3.5 \times 10^5/mm^3$.

Cell fragments from megakaryocytes. Essential for hemostasis (blood clotting).\ 4. Blood Groups (ABO System): Based on antigens (A, B) on RBC surface and antibodies (anti-A, anti-B) in plasma.\ * Type A: A antigen, anti-B antibody.

\ * Type B: B antigen, anti-A antibody.\ * Type AB: A and B antigens, no antibodies (Universal Recipient).\ * Type O: No antigens, anti-A and anti-B antibodies (Universal Donor).\ 5. Rh System: Rh antigen (D antigen).

Rh+ (has D antigen), Rh- (no D antigen). Rh incompatibility: Rh- mother + Rh+ fetus can lead to erythroblastosis fetalis (hemolytic disease of newborn) in subsequent pregnancies.\ 6. Blood Coagulation (Hemostasis): Prevents blood loss.

Injury \rightarrow Platelet plug formation \rightarrow Coagulation cascade (extrinsic/intrinsic pathways) \rightarrow Prothrombinase converts Prothrombin to Thrombin \rightarrow Thrombin converts Fibrinogen (soluble) to Fibrin (insoluble) \rightarrow Fibrin mesh forms clot.

Calcium ions ($Ca^{2+}$) and Vitamin K are crucial for clotting factor synthesis.\ 7. Lymph: Colorless fluid. Formed from interstitial fluid entering lymphatic capillaries. Composition: Similar to plasma but lower protein, rich in lymphocytes, no RBCs.

Functions: Returns interstitial fluid to blood, absorbs fats (lacteals), immunity (lymph nodes filter pathogens, house lymphocytes).

Vyyuha Quick Recall

For WBC abundance (most to least): Never Let Monkeys Eat Bananas.\nNeutrophils (60-65%)\nLymphocytes (20-25%)\nMonocytes (6-8%)\nEosinophils (2-3%)\nBasophils (0.5-1%)