Explore detailed notes on B.Pharm 1st Semester Human Anatomy and Physiology Unit 3, covering body fluids, blood composition, hemopoiesis, hemoglobin formation, anemia, blood coagulation, blood groups, Rh factor, transfusion, and the lymphatic system. Perfect for pharmacy students preparing for exams.
Unit 3: Body Fluids and Blood
1. Body Fluids
The human body consists of nearly 60% water, which is distributed throughout the body in various compartments. These fluids are essential for maintaining homeostasis, transporting nutrients, and removing waste products.
1.1 Total Body Water and Compartments
Total body water is divided into two major compartments:
- Intracellular fluid (ICF) — fluid inside the cells (about 2/3 of total body water)
- Extracellular fluid (ECF) — fluid outside the cells (about 1/3 of total body water), further subdivided into:
- Plasma (fluid portion of blood)
- Interstitial fluid (fluid between the tissue cells)
- Transcellular fluid (CSF, synovial fluid, etc.)
1.2 Composition of Body Fluids
- Water — solvent for biochemical reactions
- Electrolytes — sodium, potassium, chloride, bicarbonate, calcium, magnesium
- Proteins — especially in plasma
- Nutrients — glucose, amino acids, fatty acids
- Gases — oxygen, carbon dioxide
1.3 Functions of Body Fluids
✅ Maintain temperature
✅ Medium for biochemical reactions
✅ Transport of nutrients and gases
✅ Removal of waste
✅ Lubrication of joints and organs
2. Blood
Blood is a specialized connective tissue circulating in the cardiovascular system. It is vital for sustaining life and supporting various functions.
2.1 Composition of Blood
Blood has two major components:
- Plasma (about 55% of blood) — the liquid portion
- 90% water
- 7% proteins (albumin, globulins, fibrinogen)
- 3% solutes (glucose, urea, hormones, electrolytes, etc.)
- Formed elements (about 45% of blood):
- Erythrocytes (RBCs) — oxygen transport
- Leukocytes (WBCs) — defense
- Thrombocytes (platelets) — clotting
The normal blood volume in an adult is approximately 5–6 liters.
2.2 Functions of Blood
✅ Transport of oxygen, carbon dioxide, nutrients, hormones
✅ Regulation of pH, temperature, and water content
✅ Protection against infections via WBCs
✅ Clotting to prevent blood loss
2.3 Hemopoiesis (Blood Cell Formation)
Hemopoiesis is the process of formation of blood cells. It occurs primarily in the red bone marrow.
- Erythropoiesis: formation of RBCs
- Leukopoiesis: formation of WBCs
- Thrombopoiesis: formation of platelets
Stem cells in the bone marrow differentiate into various types of blood cells under the influence of growth factors like erythropoietin.
2.4 Formation of Hemoglobin
Hemoglobin is a conjugated protein found in RBCs. It consists of:
- 4 polypeptide chains (globin)
- 4 heme groups containing iron
Synthesis of hemoglobin requires iron, vitamin B12, folic acid, and adequate protein. It is essential for carrying oxygen from lungs to tissues and transporting carbon dioxide from tissues to lungs.
2.5 Anemia
Anemia is a condition where there is a decrease in the oxygen-carrying capacity of blood due to low hemoglobin or fewer RBCs.
Types of anemia:
- Iron deficiency anemia
- Pernicious anemia (vitamin B12 deficiency)
- Hemolytic anemia (destruction of RBCs)
- Aplastic anemia (failure of bone marrow)
Symptoms:
- Fatigue
- Pallor
- Weakness
- Shortness of breath
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2.6 Mechanism of Blood Coagulation
Coagulation prevents blood loss after injury. It involves a series of clotting factors working in a cascade:
✅ Intrinsic pathway (activated by damage to blood vessels)
✅ Extrinsic pathway (activated by tissue injury)
Both pathways converge to form prothrombin activator, which converts prothrombin to thrombin. Thrombin converts fibrinogen to fibrin, which forms a clot.
Calcium ions and vitamin K are essential for clotting.
2.7 Blood Grouping
Blood grouping is based on the presence or absence of antigens on the surface of RBCs.
✅ ABO System
- Group A — antigen A, antibody B
- Group B — antigen B, antibody A
- Group AB — antigens A & B, no antibody (universal recipient)
- Group O — no antigen, antibodies A & B (universal donor)
✅ Rh System
- Rh positive (presence of D antigen)
- Rh negative (absence of D antigen)
Erythroblastosis fetalis is a hemolytic disease of newborn due to Rh incompatibility.
2.8 Blood Transfusion
Transfusion means giving blood from one person to another.
- Requires cross-matching to prevent reactions
- Must check compatibility of both ABO and Rh
- Stored blood should be fresh and screened
Complications of transfusion:
- Transfusion reactions
- Infections (if screening fails)
- Volume overload
2.9 Disorders of Blood
✅ Leukemia — cancer of WBCs
✅ Hemophilia — deficiency of clotting factors
✅ Thalassemia — defective hemoglobin
✅ Polycythemia — increased RBC count
2.10 Reticuloendothelial System (RES)
The RES is a network of phagocytic cells which help to remove foreign particles and old blood cells.
- Components: macrophages in liver (Kupffer cells), spleen, lymph nodes, bone marrow
- Functions:
- Phagocytosis
- Defense against infection
- Removal of worn-out RBCs
- Storage of iron
3. Lymphatic System
The lymphatic system is an accessory circulatory system that drains excess tissue fluid, filters it, and returns it to the bloodstream.
3.1 Lymphatic Organs and Tissues
✅ Primary lymphoid organs
- Thymus (T-cell maturation)
- Bone marrow (B-cell development)
✅ Secondary lymphoid organs
- Lymph nodes
- Spleen
- Tonsils
- Mucosa-associated lymphoid tissue (MALT)
3.2 Lymphatic Vessels
Lymphatic vessels begin as blind-ended lymph capillaries, which collect interstitial fluid. This fluid, now called lymph, is transported through progressively larger lymph vessels, filtered through lymph nodes, and finally drains into the thoracic duct or right lymphatic duct, which empty into the subclavian veins.
3.3 Lymph Circulation
- Tissue fluid enters lymph capillaries
- Moves through lymph nodes (where immune cells screen for pathogens)
- Ultimately returns to venous circulation
- One-way flow maintained by valves and muscle contraction
3.4 Functions of the Lymphatic System
✅ Returns excess interstitial fluid to blood
✅ Absorbs fats and fat-soluble vitamins from intestine (via lacteals)
✅ Provides immune surveillance (lymphocytes and macrophages destroy pathogens)
✅ Maintains fluid balance
3.5 Clinical Aspects of the Lymphatic System
- Edema — accumulation of interstitial fluid if lymphatic drainage is blocked
- Lymphedema — severe lymph accumulation
- Lymphadenopathy — enlarged lymph nodes, common in infections or cancers
- Lymphomas — cancers of lymphoid tissue (e.g., Hodgkin’s lymphoma)