BIOM 3200 Study Guide - Final Guide: Internal Intercostal Muscles, Intrapleural Pressure, Respiratory Tract

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Unit 10: Respiratory
The Respiratory System
Divided into respiratory zone (site of gas exchange between air and blood) and conducting zone
Respiration has 3 main functions:
1. Ventilation breathing
2. Gas exchange0 occurs between air and blood in the lungs and between the blood and other
tissues of the body
3. Oxygen utilization by the tissue in the energy-liberating reactions of cell respiration
External respiration ventilation and exchange of gases (oxygen & CO2) between air and blood
Internal respiration gas exchange between blood and other tissues and oxygen utilization by tissues
Ventilation mechanical process that moves air into and out of the lungs
- Oxygen diffuses from air to blood
- Carbon dioxide moves from the blood to the air within the lungs by diffusing down its
concentration gradient
- Blood leaving the lungs (in the pulmonary veins) has a higher O2 and lower CO2 concentration
than blood delivered to the lungs in the pulmonary arteries
Structure of the Respiratory System
Alveoli tiny air sacs that facilitate gas exchange in the lungs
- Diffusion rate between alveolar air and capillary blood depends on the distance separating them
- Air within 1 member of a cluster can enter other members through tiny pores
- Alveoli clusters are at the ends of respiratory bronchioles (thin air tubes)
Two types of alveolar cells
- Type I very thin
Comprise 95% of total surface area of the lung
Facilitates most gas exchange
- Type II
Secretes pulmonary surfactant
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Reabsorbs Na+ and H2O, preventing fluid buildup within the alveoli
Two functional zones of the respiratory system
1. Respiratory zone gas exchange occurs
Includes respiratory bronchioles and terminal alveolar sacs
2. Conducting zone
Includes all of the anatomical structure through which air passes before reaching the
respiratory zone mouth, nose pharynx, larynx, trachea, primary bronchi, branching of
bronchioles to the terminal bronchioles. Function: warming and humidification of inspired
air, filtration and cleaning
Terminal bronchioles
- Air enters the respiratory bronchioles from terminal bronchioles the narrowest of the airways
that do not have alveoli and do not contribute to gas exchange
- Receive air from larger airways, which are formed from the successive branching of the right
and left primary bronchi
Air passages continuous with the trachea (windpipe) located in the neck in front of the
esophagus
Trachea is a sturdy tube supported by rings of cartilage
When inspired air reaches the respiratory zone, it is at 37 degrees C (body temp.)
- Saturated with water vapour as it flows over the war, wet mucous membranes that line the
respiratory airways to ensure constant internal body temp.
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Mucus secreted by cells trap particles of inspired air and filter it
- Moves at 1-2 cm per minute by projecting cilia from the top of the epithelial cells lining the
conducting zone
- Particles larger than 6 micrometers cannot enter the respiratory zone
Thoracic Cavity
The diaphragm is a sheet of striated muscle, dividing the anterior body cavity into 2 parts
- The abdominopelvic cavity is below the diaphragm contains the liver, pancreas, GI tract,
spleen, genitourinary tract
- The thoracic cavity is above the diaphragm contains the heart, large blood vessels, trachea,
esophagus, thymus, and lungs
The central region is enveloped by 2 layers of wet epithelial membrane (pleural membranes)
- The parietal pleura (superficial layer) lines the thoracic wall
- The visceral pleura (deep layer) covers the surface of the lungs
-Intrapleural space is the small space between the touching pleural membranes
Physical Aspects of Ventilation
Movement of air from high to low pressure between the conducting zone and terminal bronchioles
occurs as a result of pressure different between the two ends of the airways
- Airflow through the bronchioles is directly proportional to the pressure difference and inversely
proportional to the frictional resistance to flow
- The pressure differences in the pulmonary system are induced by changes in lung volumes
Intrapulmonary and Intrapleural Pressures
The visceral and parietal pleurae and stuck together like 2 pieces of wet glass
- The intrapleural space (fluid) is secreted by the parietal pleura
Formed as a filtrate from blood capillaries
Serves as a lubricant
Air enters the lungs during inspiration because the atmospheric pressure is greater than the
intrapulmonary (intra-alveolar) pressure
-Inspiration the intrapulmonary pressure must fall below atmospheric pressure
Sub-atmospheric (negative) pressure
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