Q_ What is perfusion

Perfusion

• Definition: Flow of blood through arteries and capillaries, essential for delivering oxygen and nutrients, while removing waste.

• Importance of Oxygen: Vital for perfusion; blood must carry oxygen to tissues. Without adequate oxygenation, tissue function is compromised.

• Good Perfusion Effects: Tissues receive sufficient oxygen and nutrients, maintaining health.

• Implications of Impaired Perfusion: Can lead to reduced oxygen/nutrient delivery, resulting in tissue damage or death.

Types of Perfusion

• Central Perfusion: Refers to heart’s efficiency in pumping blood throughout the body.

• Peripheral Perfusion: Indicates blood flow to specific tissues such as muscles and organs.

• Relationship: Central perfusion directly affects peripheral perfusion; inadequate heart function reduces blood supply to tissues.

Cardiac Cycle

• Definition: Transition between heart filling with blood (diastole) and pumping it out (systole).

• Preload: Amount of blood in the heart before contraction.

• Afterload: Resistance against which the heart must pump blood.

• Coronary Arteries: Right coronary artery (RCA) and left coronary artery (LCA).

• Coronary Blood Flow Timing: Occurs during diastole when the heart muscle relaxes.

• Sinoatrial (SA) Node: Functions as the natural pacemaker, generating electrical signals for heartbeat initiation.

SA Node and Heart Function

• Intrinsic Rate of SA Node: 60-100 beats per minute (bpm).

• Failure of SA Node: The atrioventricular (AV) node compensates, maintaining heart rate at 40-60 bpm.

• AV Node Intrinsic Rate: 40-60 bpm.

• His-Purkinje System Intrinsic Rate: 20-40 bpm.

Receptors and Cardiac Regulation

• Baroreceptors: Detect changes in blood pressure; regulate heart rate accordingly.

• Chemoreceptors: Monitor CO₂ and pH levels in the blood; adjust heart rate for homeostasis.

Cardiac Cell Properties

• Automaticity: Cardiac cells' ability to generate electrical impulses independently.

• Excitability: Responsiveness of cardiac cells to electrical stimuli.

• Conductivity: Capacity of cardiac cells to transmit electrical impulses to adjacent cells.

• Contractility: Strength of the heart's contraction during systole.