Chapter 15: Body Fluids and Circulation

Introduction

• All living cells require nutrients, O2, and removal of waste.
• Efficient transport mechanisms are essential.
• Blood and Lymph are key fluids in higher organisms for transport.

15.1 Blood

• Blood: A special connective tissue with plasma (fluid matrix) and formed elements.

15.1.1 Plasma

• Plasma: Straw-colored fluid, 55% of blood.
  • 90-92% water, 6-8% proteins (Fibrinogen, Globulins, Albumins).
  • Functions: Clotting, defense, osmotic balance.
  • Minerals (Na+, Ca++, etc.) and nutrients present.
  • Serum: Plasma without clotting factors.

15.1.2 Formed Elements

• Erythrocytes (RBCs)
  • Most abundant, contain hemoglobin for oxygen transport.
  • Life span: 120 days.
• Leucocytes (WBCs)
  • Defense functions, divided into granulocytes (Neutrophils, Eosinophils, Basophils) and agranulocytes (Lymphocytes, Monocytes).
• Platelets
  • Fragments, crucial for blood clotting.

15.1.3 Blood Groups

• ABO Grouping: Based on antigens A and B.
• Rh Grouping: Based on Rh antigen presence.
• Universal Donors: O group.
• Universal Recipients: AB group.
• Erythroblastosis Foetalis: Rh incompatibility issue between mother and fetus.

15.1.4 Coagulation of Blood

• Describes the mechanism of blood clotting involving fibrinogens, thrombin, and prothrombin.

15.2 Lymph (Tissue Fluid)

• Derived from blood, contains lymphocytes and nutrients.
• Functions: Immune responses, nutrient transport.
• Absorption of fats through lymph.

15.3 Circulatory Pathways

• Open vs. Closed Circulatory System
• Vertebrates possess a closed circulatory system.

15.3.1 Human Circulatory System

• Composed of heart, blood vessels, and blood.
• Heart: Four chambers (2 atria, 2 ventricles), valves ensure one-way blood flow.
• Nodal Tissue: SAN (pacemaker), AVN, AV Bundle, Purkinje Fibers.

15.3.2 Cardiac Cycle

• Sequence of systole and diastole in heart chambers.
• Cardiac Output: Volume of blood pumped per minute (Stroke volume x Heart Rate).
• Heart sounds: Lub (closure of AV valves), Dub (closure of semilunar valves).

15.3.3 Electrocardiogram (ECG)

• ECG depicts electrical activity of heart.
• Waves: P-wave (atrial depolarization), QRS complex (ventricular depolarization), T-wave (ventricular repolarization).

15.4 Double Circulation

• Pulmonary Circulation: Heart -> Lungs -> Heart
• Systemic Circulation: Heart -> Body -> Heart

15.5 Regulation of Cardiac Activity

• Intrinsic regulation by nodal tissue (myogenic nature).
• ANS modulates cardiac function (sympathetic increases, parasympathetic decreases activity).

15.6 Disorders of Circulatory System

• Hypertension: High blood pressure.
• Coronary Artery Disease: Atherosclerosis affects heart's blood supply.
• Angina: Chest pain due to reduced blood flow.
• Heart Failure: Inadequate pumping of blood.

Summary

• Overview of blood, lymph, circulatory pathways, cardiac cycle, ECG, and circulatory disorders.

Exercises

1. Describe blood components and their functions.
2. Importance of plasma proteins.
3. Match components with functions.
4. Explanation of blood as a connective tissue.
5. Differences between lymph and blood, open and closed systems, etc.
6. Discuss double circulation and its significance.
7. Explain cardiac cycle, heart sounds, and ECG segments.