Lecture Notes on Circulatory System

Introduction

• Lecture focused on the circulatory system, starting with human anatomy.
• The presenter emphasized the importance of detailed slides and interactions.

Overview of Circulatory System

• Circulatory system revolves around blood.
• Blood is a body fluid that flows, moving from one place to another.
• Components of the circulatory system include:
  • Heart
  • Blood Vessels (Arteries, Veins, and Capillaries)

Blood Characteristics

• Blood is always moving and never stationary.
• Arterial Blood:
  • Bright red due to oxygen.
• Venous Blood:
  • Dark red, indicating lack of oxygen.
• Human body contains approximately 5-6 liters of blood.
• pH value of blood is approximately 7.45, slightly alkaline.

Tissue Fluid and Lymph

• Tissue Fluid:
  • Delivers oxygen, amino acids, glucose, and fatty acids to every cell.
  • Removes waste products like CO2.
• Lymph:
  • Contains lymphatic vessels and organs (e.g., spleen, tonsils).

Blood Flow in Animals

• In insects, blood flows through open spaces, unlike humans who have a closed circulatory system.
• Blood circulates through the heart, which pumps oxygenated blood.

Non-Circulating Fluids

• Some fluids are stationary, such as:
  • Synovial Fluid in joints (for lubrication).
  • Vitreous Humor in the eye (maintains shape).

Functions of Blood

• Transports digested food and nutrients.
• Transports Oxygen: Forms unstable compounds with hemoglobin.
• Transports CO2: Converts to carbonic acid for removal.
• Excretes Waste Materials: Via renal arteries and veins.
• Distributes Hormones and regulates body heat.

Composition of Blood

• Blood consists mainly of:
  • Plasma (mostly water)
  • Cellular Elements: Red Blood Cells (RBCs), White Blood Cells (WBCs), Platelets.

Red Blood Cells (RBCs)

• Known as oxygen carriers.
• Average lifespan: 120 days.

White Blood Cells (WBCs)

• Types include: Neutrophils, Basophils, Eosinophils, Lymphocytes, Monocytes.
• Average lifespan: 5-6 days.
• Functions include:
  • Phagocytosis: Engulfing pathogens.
  • Antibody Formation: Produced by lymphocytes.

Platelets

• Initiators of blood clotting, lifespan of 3-5 days.

Blood Clotting Process

• Involves thrombin and fibrinogen converting into fibrin to form clots.
• Thrombin activates fibrinogen in the presence of calcium ions.

Blood Transfusion

• Importance of the Rh factor discovered in Rhesus monkeys.
• Blood Groups: A, B, AB, O (Universal Donor).

Heart Anatomy

• Four-Chamber Heart: Left and right atria, left and right ventricles.
• Covered by a double-walled membrane known as pericardium.
• Valves: Tricuspid and bicuspid (mitral) prevent backflow of blood.

Heart Function

• Blood flows from body to heart via veins and pumped to the body through arteries.
• Cardiac Cycle: Includes systole (contraction) and diastole (relaxation).
• Heartbeat sounds (lub-dub) associated with closure of valves.

Blood Pressure

• Systolic and Diastolic Pressure: Measures of blood pressure during heartbeats and between beats, respectively.
• Hypertension: Blood pressure above 140/90 mmHg.

Spleen

• Functions as a blood reservoir and produces lymphocytes.
• Acts as a graveyard for RBCs.

Hepatic Portal System

• Comprises veins that carry blood from the stomach and intestines to the liver.
• Allows detoxification and nutrient storage.

Conclusion

• Covered all aspects of the circulatory system in detail.
• Encourage feedback and request for likes to continue with further topics.