BIOL 2420 Lecture Notes - Lecture 1: Respiratory Tract, Intercostal Muscle, Thoracic Wall

Unit 5 – Lecture 1
The Respiratory System
- The word respiration has several meanings
o Cellular respiration: the intracellular reaction of oxygen with organic molecules to
produce carbon dioxide, water, and energy in the form of ATP
o External respiration: the oeet of gases betee the eiroet ad the body’s
cells
▪ Can be subdivided into 4 integrated processes
1. Exchange of air between the atmosphere and the lungs
• Known as ventilation – breathing
• Inspiration: the movement of air into the lungs
• expiration: the movement of air out of the lungs
• mechanisms of ventilation are called the mechanics of breathing
2. Exchange of O2 and CO2 between the lungs and the blood
3. Transport of O2 and CO2 by the blood
4. Exchange of gases between blood and the cells
- External respiration requires coordination between the respiratory and cardiovascular systems
o Respiratory system: structures involved in ventilation and gas exchange
1. Conducting system of passages or airways that lead from the external environment
to the exchange surface of the lungs
2. Alveoli: series of interconnected sacs and their associated pulmonary capillaries
▪ Form exchange surfaces where oxygen moves from inhaled air to the blood and
carbon dioxide moves from the blood to the air that is being exhaled
3. The bones and muscles of the thorax (chest cavity) and abdomen that assist in
ventilation
Anatomy Summary
The respiratory system is divided into two parts
- Upper respiratory tract: the mouth, nasal cavity, pharynx, and larynx
- Lower respiratory tract: trachea, two primary bronchi, their branches, and the lungs
o Known as the thoracic portion of the respiratory system because it is enclosed in the
thorax
Bones and Muscles of the Thorax Surround the Lungs
- Thorax is bound by the bones of the spine and rib cage and their associated muscles
o Together the bones and muscles are called the thoracic cage
o Ribs and spin (chest wall) form the sides and top of the cage
▪ Dome-shaped sheet of skeletal muscle, the diaphragm, forms the floor
- Intercostal muscles:
o the internal and external (i.e. 2 sets)
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