BIOL 121 Chp 23: The Respiratory System
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Transcript of BIOL 121 Chp 23: The Respiratory System
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Chapter 23
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Rob SwatskiAsst. Prof. Biology
HACC – York Campus
The Respiratory System
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The 2 systems that cooperate to supply O2 & eliminate CO2 are the cardiovascular & the respiratory system
Respiratory system provides for gas exchangeCardiovascular system transports the respiratory gases
Failure of either system has the same effect on the body:
- disruption of homeostasis- rapid death of cells: O2 starvation & buildup of
wastes
Introduction
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Respiration
The exchange of gases between the atmosphere, blood, & cells
3 basic steps:
1. Ventilation (breathing)
2. External (pulmonary) respiration
3. Internal (tissue) respiration
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Respiratory System Anatomy
Nose
Pharynx = throat
Larynx = voicebox
Trachea = windpipe
Bronchi = airways
Lungs
Locations of infections:
- upper respiratory tract is above vocal cords
- lower respiratory tract is below vocal cords
Conducting system consists of a series of cavities & tubes - nose, pharynx, larynx, trachea, bronchi, bronchiole, & terminal bronchioles - that conduct air into the lungs
Respiratory portion consists of the area where gas exchange occurs - respiratory bronchioles, alveolar ducts, alveolar sacs, & alveoli 5
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Pharynx
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Larynx
Cartilage & CT tube
Anterior to C4 to C6
Constructed of 3 single & 3 paired cartilages8
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Cartilages of the Larynx
Epiglottis: leaf-shaped piece of elastic cartilage– during swallowing, larynx moves upward– epiglottis bends to cover glottis
Cricoid cartilage: ring of cartilage attached to top of trachea
Pair of arytenoid cartilages sit upon cricoid– many muscles responsible for their movement– partially buried in vocal folds (true vocal cords) 9
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Trachea & Bronchial Tree
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Airway Epithelium
Ciliated pseudostratified columnar epithelium with goblet cells produce a moving mass of mucus
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Bronchi
The trachea divides into the:
right & left pulmonary bronchi
The bronchial tree consists of the:
trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, & terminal bronchioles
Bronchi walls: contain rings of cartilage
Bronchiole walls: contain smooth muscle
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Bronchi & Bronchioles
Primary bronchi supply each lung
Secondary bronchi supply each lobe of the lungs (3 right + 2 left)
Tertiary bronchi supply each bronchopulmonary segment
Repeated branchings called bronchioles form the bronchial tree 13
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Branchings of single arteriole, venule & bronchiole are wrapped by elastic CT
Respiratory bronchiole: simple squamous epithelium
Alveolar ducts surrounded by alveolar sacs & alveoli
– sac is 2 or more alveoli sharing a common opening 14
Structures Within a Lobule of Lung
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Cells Types of the Alveoli
Type I alveolar cells
– simple squamous cells where gas exchange occurs
Type II alveolar cells (septal cells)
– free surface has microvilli
– secrete alveolar fluid containing surfactant
Alveolar dust cells (macrophages)
– wandering macrophages remove debris
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Details of the
Respiratory Membrane
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Pulmonary Ventilation
Respiration occurs in 3 basic steps: pulmonary ventilation, external respiration, & internal respiration
Inspiration (inhalation) is the process of bringing air into the lungs
The movement of air into & out of the lungs depends on pressure changes governed in part by Boyle’s law, which states that the volume of a gas varies inversely with pressure, assuming that temperature is constant
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As the size of a closed container decreases, the pressure inside increases
The molecules have less wall area to strike so the pressure on each inch of area increases
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Boyle’s Law
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Dimensions of the Chest Cavity
Inhalation requires muscular contraction & chest size changes
Contraction of the diaphragm flattens the dome & increases the vertical dimension of the chest
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Quiet Inspiration
Diaphragm lowers 1 cm & ribs lifted by muscles
Intrathoracic pressure falls & 2-3 liters inhaled20
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Quiet Expiration
Passive process with no muscle action
Elastic recoil & surface tension in alveoli pulls inward
Alveolar pressure increases & air is pushed out21
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Labored Breathing
Forced inspiration
– sternocleidomastoid, scalenes & pectoralisminor lift chest upwards as you gasp for air
Forced expiration
– abdominal musclesforce diaphragm up
– internal intercostalsdepress ribs
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IntrapleuralPressures
Always subatmospheric(756 mm Hg)
As diaphragm contracts intrathoracicpressure decreaseseven more
(754 mm Hg)
Helps keep parietal & visceral pleura sticking together
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Alveolar pressure decreases & air rushes in
Alveolar pressure increases & air rushes out 24
Summary of Breathing