Overview
This lecture covers the respiratory and circulatory systems, their parts, functions, and how they work together to transport nutrients and gases in the human body.
Respiratory System
- The respiratory system is responsible for taking in oxygen and expelling carbon dioxide.
- Main parts: nose/mouth (air entry), nasal cavity (filters and warms air), pharynx (throat), larynx (voice box), trachea (windpipe), lungs (main organs), bronchi (branching tubes), bronchioles (smaller branches), and alveoli (site of gas exchange).
- During inhalation: oxygen enters, ribs move out, chest space increases, diaphragm contracts (moves down).
- During exhalation: carbon dioxide exits, ribs move in, chest space decreases, diaphragm relaxes (moves up).
Circulatory System
- The circulatory (cardiovascular) system delivers materials like oxygen and nutrients and removes waste.
- Main parts: heart (pumps blood), blood vessels (arteries, veins, capillaries), and blood.
- Arteries carry blood away from the heart, veins carry blood to the heart, capillaries exchange gases and nutrients.
- Blood transports oxygen, nutrients, and waste throughout the body.
The Heart and Blood Flow
- The heart is a hollow muscle about the size of your fist with four chambers: right/left atria (receive blood) and right/left ventricles (pump blood).
- Blood flow: enters right atrium via vena cava → tricuspid valve → right ventricle → pulmonary valve → pulmonary artery (to lungs) → pulmonary vein → left atrium → bicuspid valve → left ventricle → aortic valve → aorta (to body).
Interaction of Respiratory and Circulatory Systems
- Oxygen from inhaled air enters lungs, moves to heart, and is pumped by heart to all body cells.
- Oxygen helps release energy from nutrients and carbon dioxide (waste) is produced.
- Blood returns carbon dioxide to the heart, which is then sent to lungs to be exhaled.
Types of Circulation
- Pulmonary circulation: blood moves from heart to lungs and back.
- Coronary circulation: blood moves through the heart’s tissue only.
- Systemic circulation: blood moves from heart to the rest of the body (except lungs).
Key Terms & Definitions
- Respiratory System — organ system for breathing (taking in oxygen, releasing carbon dioxide).
- Circulatory System — organ system for transporting blood, nutrients, oxygen, and waste.
- Alveoli — small sacs in lungs where gas exchange occurs.
- Diaphragm — muscle that aids breathing by moving up and down.
- Atrium (plural: atria) — receiving chambers of the heart.
- Ventricle — pumping chambers of the heart.
- Artery — vessel carrying blood away from the heart.
- Vein — vessel carrying blood toward the heart.
- Capillary — smallest blood vessel, site of exchange.
- Pulmonary Circulation — blood flow between heart and lungs.
- Systemic Circulation — blood flow between heart and body.
- Coronary Circulation — blood flow within the heart tissue.
Action Items / Next Steps
- Review the parts/functions of the respiratory and circulatory systems.
- Study the pathway of blood through the heart and body.
- Learn the three types of circulation and their roles.