Download comprehensive B.Pharm 1st semester Human Anatomy and Physiology Unit 5 notes on the Cardiovascular System, including heart structure, cardiac cycle, circulation, and ECG. Clear, exam-focused PDF available for free.
Unit 5
Cardiovascular system
Heart – anatomy of heart, blood circulation, blood vessels, structure and functions of artery, vein and capillaries, elements of conduction system of heart and heart beat, its regulation by autonomic nervous system, cardiac output, cardiac cycle. Regulation of blood pressure, pulse, electrocardiogram and disorders of heart.
Cardiovascular System (HAP Unit 5)
Introduction
- The cardiovascular system consists of the heart, blood, and blood vessels.
- Its main role is to transport nutrients, gases, hormones, and metabolic wastes throughout the body.
Structure of the Heart
✅ Location: Thoracic cavity, in the mediastinum, slightly left-oriented
✅ Size: About the size of a clenched fist
✅ Covering: Pericardium (fibrous sac with fluid to reduce friction)
✅ Chambers: 4 total
- Right atrium
- Right ventricle
- Left atrium
- Left ventricle
✅ Valves: Prevent backflow of blood - Atrioventricular (tricuspid and bicuspid/mitral)
- Semilunar (pulmonary and aortic)
Blood Vessels
✅ Arteries – carry blood away from the heart
✅ Veins – carry blood toward the heart
✅ Capillaries – connect arterioles and venules, allow exchange of substances
Conducting System of the Heart
- Heart muscle is myogenic (generates its own impulse)
- Conducting structures:
- SA node (sinoatrial node, natural pacemaker)
- AV node (atrioventricular node)
- Bundle of His
- Purkinje fibers
This system coordinates the rhythmic contraction of the heart.
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Cardiac Cycle
Definition: The sequence of events in one complete heartbeat.
✅ Phases:
- Atrial systole (atria contract, ventricles fill)
- Ventricular systole (ventricles contract, blood ejected)
- Complete cardiac diastole (all chambers relaxed, blood fills atria)
Duration: ~0.8 seconds per cycle
Heart rate: about 72 beats per minute on average
Cardiac Output
Definition: The amount of blood pumped by each ventricle per minute
👉 Formula: Cardiac Output=Heart Rate×Stroke Volume\text{Cardiac Output} = \text{Heart Rate} \times \text{Stroke Volume}Cardiac Output=Heart Rate×Stroke Volume
Average CO ~5 liters/min
Regulation of Heart Function
- Autonomic Nervous System:
- Sympathetic ↑ heart rate
- Parasympathetic ↓ heart rate
- Hormonal: adrenaline increases heart rate
- Intrinsic: SA node activity
Types of Circulation
✅ Systemic circulation – from left ventricle to the body and back to the right atrium
✅ Pulmonary circulation – from right ventricle to lungs and back to the left atrium
✅ Portal circulation – blood from digestive organs to liver (via portal vein)
Blood Pressure
✅ Definition: lateral pressure exerted by blood on vessel walls
✅ Normal: 120/80 mmHg
✅ Regulation:
- cardiac output
- peripheral resistance
- blood volume
Electrocardiography (ECG)
✅ ECG: measures the electrical activity of the heart
✅ Normal waves:
- P wave (atrial depolarization)
- QRS complex (ventricular depolarization)
- T wave (ventricular repolarization)
✅ Uses: diagnose arrhythmias, myocardial infarction, conduction block