Psychological Structure and Life Process

Physiological Structure and Life Processes: Blood Circulation in Human Body

1. Circulatory System

Definition: The system that transports blood, oxygen, nutrients, hormones, and wastes throughout the body.
Main organ: Heart
Other components: Blood vessels (arteries, veins, capillaries), blood

Function:

Transports oxygen, nutrients, hormones to all cells

Removes wastes (CO₂, urea) to excretory organs

Connects other organ systems (digestive, respiratory, endocrine)

2. Blood

Definition: Red-colored connective tissue that circulates in the body.
Composition:

Plasma (55%): pale yellow liquid, 80–90% water + dissolved substances (proteins, carbs, salts, hormones, enzymes)

Blood cells (45%): Red blood cells, White blood cells, Platelets

Functions:

Transportation: Oxygen, CO₂, nutrients, hormones, wastes

Regulation: Body temperature, water balance, pH

Protection: WBCs fight infection, platelets clot blood

Blood Corpuscles

a. Red Blood Cells (RBC / Erythrocytes)

Biconcave, nucleus-free, red

Contain hemoglobin (iron + protein globin) → binds O₂ and CO₂

Life span: 90–120 days

Produced in bone marrow, destroyed in liver & spleen

Deficiency → Anemia; Excess → Polycythemia

b. White Blood Cells (WBC / Leucocytes)

Larger, nucleated, no hemoglobin

Types:

Granular: Neutrophil, Eosinophil, Basophil

Non-granular: Lymphocytes, Monocytes

Life span: ~2 weeks

Function: Fight infections → “soldiers of the body”

Deficiency → Leukopenia, Excess → Leukemia

c. Platelets (Thrombocytes)

Smallest, non-nucleated

Function: Blood clotting (with fibrinogen)

Deficiency → Hemophilia, Excess → Thrombocytosis

3. Blood Groups

Determined by antigens on RBC surface: A, B, AB, O

Also contains Rh factor (D antigen) → Positive (+) / Negative (–)

Total blood groups = 8 (A+, A–, B+, B–, AB+, AB–, O+, O–)

Importance: Compatibility in blood transfusions

4. Heart

Definition: Muscular organ that pumps blood to all parts of the body.

Size: About a fist, ~300 g

Location: Thoracic cavity, slightly left

Protected by pericardium (double-layered membrane)

Structure:

Four chambers: Right & Left Auricle (atrium), Right & Left Ventricle

Septum: Prevents mixing of oxygenated & deoxygenated blood

Valves: Tricuspid, Bicuspid/Mitral, Pulmonary, Aortic

Blood vessels:

Veins → bring blood to heart (superior & inferior vena cava, pulmonary veins)

Arteries → carry blood from heart (aorta, pulmonary artery)

Function: Pump blood → supplies oxygen/nutrients and removes wastes

Blood Circulation

1. Systemic Circulation:

Oxygenated blood → Left ventricle → aorta → body → deoxygenated blood → right auricle via veins

2. Pulmonary Circulation:

Deoxygenated blood → Right ventricle → pulmonary artery → lungs → oxygenated blood → left auricle via pulmonary veins

5. Heartbeat & Pulse

Heartbeat: Rhythmic contraction & relaxation of heart

Pulse: Expansion of artery walls as blood flows

Normal rate: 60–100/min

Bradycardia: <60/min, Tachycardia: >100/min

6. Blood Vessels

Arteries: Thick, muscular, no valves, carry blood away from heart

Veins: Thin-walled, valves prevent backflow, carry blood to heart

Capillaries: Microscopic, allow exchange of gases, nutrients, and wastes

7. Blood Pressure

Definition: Pressure exerted by blood on artery walls

Systolic: During ventricular contraction

Diastolic: During ventricular relaxation

Normal: 120/80 mmHg

High BP (Hypertension): >140/90 mmHg

Causes: Obesity, stress, salty/fatty food, smoking, lack of exercise
Prevention: Healthy diet, exercise, stress management

8. Heart Attack (Myocardial Infarction)

Definition: Sudden blockage of blood flow to heart → tissue damage
Causes: Narrowed coronary arteries due to cholesterol/fat deposits (plaque)
Symptoms: Chest pain, shortness of breath, cold sweat, nausea
Treatment:

Medical: Oxygen supply, blood thinners

Surgical: Angioplasty & stenting, Coronary artery bypass

9. Disorders Related to Blood Circulation

Diabetes (Hyperglycemia): High blood sugar due to insufficient insulin

Symptoms: Thirst, frequent urination, blurred vision

Prevention: Balanced diet, exercise, active lifestyle

High Uric Acid (Hyperuricemia): Excess uric acid → joint pain, kidney stones

Causes: Purine-rich diet, low water intake

Prevention: Exercise, water intake, avoid fatty foods

Hypertension: High blood pressure

Prevention: Healthy lifestyle, avoid alcohol & smoking, exercise

3. Blood Circulation 

A. Systemic Circulation

Left Ventricle → Aorta → Arteries → Capillaries (body cells) → Veins → Vena Cava → Right Auricle

Function: Deliver O₂ & nutrients to cells, remove CO₂ & wastes

B. Pulmonary Circulation

Right Ventricle → Pulmonary Artery → Lungs → Pulmonary Vein → Left Auricle

Function: Exchange CO₂ for O₂ in lungs

4. Blood Vessel Types

Heart → Artery → Arteriole → Capillaries → Venule → Vein → Heart