Circulatory System Overview

Components of the Circulatory System

• Function:

• Delivers oxygen and nutrients to cells.

• Takes away waste products.

• Pumps blood from the heart to lungs for oxygenation.

• Transports oxygen-poor blood back to the heart.

• Main Components:

• Heart: Muscular organ regulated by electrical impulses.

• Blood: Fluid transporting oxygen, carbon dioxide, nutrients, and vitamins.

• Arteries: Vessels carrying oxygenated blood away from the heart; thicker and muscular.

• Veins: Vessels bringing oxygen-poor blood back to the heart.

• Capillaries: Small vessels facilitating the exchange of substances between blood and tissues.

The Heart

• Function:

• Muscular pump at the center of the circulatory system.

• Circulates blood to provide nutrients and remove waste.

• Anatomy:

• Has four chambers:

  • Right Atrium: Receives deoxygenated blood from the body.

  • Right Ventricle: Pumps deoxygenated blood to lungs.

  • Left Atrium: Receives oxygenated blood from the lungs.

  • Left Ventricle: Pumps oxygenated blood to the body.

• Valves: Prevent backflow of blood; can be affected by abnormalities or infections.

Heart Structure

• View:

• Anterior View includes major arteries and veins (e.g. aorta, pulmonary arteries).

• Posterior View shows the return paths of blood to the heart (e.g. superior and inferior vena cava).

• Valves:

• Each valve has 2 or 3 folds of tissue to control blood flow direction.

Phases of a Heartbeat

• Systole: Contraction phase where blood is pumped out.

• Diastole: Relaxation phase allowing chambers to refill.

• Blood Pressure:

• Measured as systolic/diastolic.

• Normal: 120/80 mmHg.

• Hypertension: High blood pressure can weaken vessels.

• Hypotension: Low blood pressure can disrupt blood flow.

Thermoregulation

• Role in Homeostasis:

• Maintains stable internal conditions by regulating blood flow.

• Mechanisms:

• Vessels near skin constrict to preserve heat or dilate to cool down.

Circulatory System Circuits

• Dual Circulation:

• Pulmonary Circuit: Pumps deoxygenated blood to lungs; returns oxygenated blood to heart.

• Systemic Circuit: Distributes oxygen-rich blood to body tissues; returns deoxygenated blood to heart.

Heart Attacks

• Myocardial Infarction:

• Occurs when blood flow to the heart is blocked.

• Often due to plaque buildup in coronary arteries.

• Prevention:

• Avoid smoking.

• Manage blood pressure & stress levels.

• Maintain a healthy diet, weight, and active lifestyle.