Circulatory System

• Double Circulatory System (discovered by William Harvey)
• Heart: Muscular organ (~250–300 g)
  • Beats 72–75 times/min
  • 4 Chambers: RA, RV, LA, LV
  • Valves:
    • Bicuspid (Left)
    • Tricuspid (Right)
    • Function: Prevents reverse blood flow

---

Blood Circulation

• Supplied by coronary artery
• Pulmonary circulation: Heart ↔ Lungs
• Systemic circulation: Heart ↔ Body

---

Arteries

• Carry oxygenated blood (except pulmonary artery)
• Red in color
• No valves
• Located deep
• Thicker, muscular walls
• Narrow cavity

Veins

• Carry deoxygenated blood (except pulmonary veins)

• Violet in color

• Valves present

• Located in upper layers

• Flattened cavity

• Hepatic portal vein: Intestine → Liver

---

Pulse & Blood Pressure

• Pulse rate:

  • High in fever & babies
  • Low during sleep

• Normal BP: 120/80 mmHg

• Measured by Sphygmomanometer

• Hypertension: >140/100 mmHg

• Hypotension: Below normal

---

Heartbeat Regulation

• Pacemaker: group of tissues generating electrochemical waves
  • Measured by Electrocardiograph (ECG)
• Controlled by:
  • Thyroxine & Adrenaline hormones
  • Medulla Oblongata

---

Blood Components

• Haemoglobin:

  • Normal state → Violet
  • With Oxygen (Oxyhaemoglobin) → Red

• Insulin: regulates blood sugar

  • Deficiency → Diabetes

---

Lymph

• Fluid similar to blood, clots like blood
• Formed in lymph nodes
• Produces lymphocytes
• Helps in diffusion
• Maintains osmotic pressure

The human circulatory system is responsible for transporting blood, oxygen, nutrients, and wastes throughout the body.
It is vital for survival, immunity, and healing. In Bihar, conditions like anemia, malnutrition, and heart disease make circulatory health a public issue.

---

Major Components of Circulatory System

1. Heart

• Muscular organ; located in chest cavity
• Has 4 chambers:
  • Right atrium & Right ventricle
  • Left atrium & Left ventricle
• Pumps oxygenated blood to the body and deoxygenated blood to lungs
• Protected by a sac called pericardium

📝 PYQ (BPSC): How many chambers are there in the human heart? → 4
📝 Expected MCQ: Which chamber pumps oxygenated blood to the body? → Left ventricle

---

2. Blood Vessels

• Arteries: Carry oxygen-rich blood away from heart (except pulmonary artery)
• Veins: Carry oxygen-poor blood toward heart (except pulmonary vein)
• Capillaries: Thin vessels for exchange of gases and nutrients

📝 Expected MCQ: Which blood vessels have valves? → Veins
📝 Expected MCQ: What connects arteries and veins? → Capillaries

---

3. Blood

• Red Blood Cells (RBCs): Carry oxygen using hemoglobin
• White Blood Cells (WBCs): Fight infection
• Platelets: Help in blood clotting
• Plasma: Yellow fluid carrying hormones, nutrients, wastes

📝 PYQ (BPSC): Which blood component helps in clotting? → Platelets

---

Types of Circulation

1. Pulmonary Circulation

   • Between heart and lungs
   • Removes CO₂ and takes in O₂

2. Systemic Circulation

   • Between heart and body
   • Delivers oxygen and nutrients to tissues

📝 Expected MCQ: Blood from lungs returns to which heart chamber? → Left atrium

---

Blood Groups (ABO System)

• 4 main types: A, B, AB, O
• Blood type is determined by presence of antigens on RBCs
• O negative is universal donor
• AB positive is universal recipient

📝 Expected MCQ: Universal donor blood group? → O negative
📝 Expected MCQ: Universal recipient? → AB positive

---

Rh Factor

• Another antigen on RBCs (Positive or Negative)
• Important in pregnancy and blood transfusion
• Rh incompatibility can harm newborns

📝 Expected MCQ: Rh factor is associated with? → Blood compatibility

---

Common Disorders

• Anemia: Low hemoglobin (widespread in Bihar)
• Hypertension: High blood pressure
• Heart attack: Blockage in coronary arteries
• Stroke: Interrupted blood flow to brain
• Thalassemia: Genetic blood disorder (prevalent in Bihar)

---

Bihar-Specific Relevance

• High anemia prevalence, especially in women and children
• Low awareness of blood donation and blood group importance
• Govt programs:
  • Anemia Mukt Bharat
  • Rashtriya Bal Swasthya Karyakram (RBSK)
  • Thalassemia screening in select districts

📝 Expected MCQ: Which program aims to reduce anemia in Bihar? → Anemia Mukt Bharat

---

PYQs + Expected MCQs

📝 PYQ (BPSC): Function of hemoglobin? → Carries oxygen
📝 PYQ (Teacher): Which component clots blood? → Platelets
📝 Expected MCQ: Which blood cells fight infection? → WBCs
📝 Expected MCQ: Universal blood donor group? → O negative
📝 Expected MCQ: Heart is protected by? → Pericardium
📝 Expected MCQ: What connects arteries to veins? → Capillaries

---

Quick Revision Points

• Heart → 4 chambers; pumps blood
• Arteries = away; Veins = toward heart
• RBCs → Oxygen; WBCs → Defense; Platelets → Clotting
• Pulmonary = lungs; Systemic = body
• Blood groups = A, B, AB, O; Rh+ or Rh–
• Bihar: High anemia, thalassemia → Govt nutrition & screening programs

---

Sources Used

• NCERT Class 10 Science – Life Processes
• Lucent GK – Biology Section
• Drishti Science Quick Book
• Ghatna Chakra PYQs – BPSC, Teacher
• EduTeria Biology Objective Capsule
• Ministry of Health – Bihar Anemia & RBSK Reports