The Respiratory System Lecture 1: Organisation of the respiratory system Human form & Function - Physiology 08-09 Mikel Egaña Trinity College Dublin
Copyright © 2005 Pearson Education, Inc., publishing as Benj amin Cummings.
Respiration lecture series: •
Mon, Jan 19 - Organization of the respiratory system
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Wed, Jan 21 - Lung mechanics
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Thur, Thur, Jan 22 - NO LECTURE
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Mon, Jan 26 - Ventilation
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Wed, Jan 28 - Gas exchange
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Thur, Thur, Jan 29 - NO LECTURE
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Mon, Feb 2 - Gas transport
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Wed, Feb 4 - Respiratory control
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Thur, Thur, Feb 5 - Effects of barometric pressure
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Lecture Slides at: http://www.medicine.tcd.ie/physiology/courses/student_area/
Physiology 08-09. Respiratory System. Lecture 1.
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Before we start… start… •
The respiratory system: •
Location: where?
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Active - passive?
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Voluntary - involuntary?
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Normal ventilation: frequency, volume?
Physiology 08-09. Respiratory System. Lecture 1.
Lecture Outline I.
Overview of Respiratory Function
II.
Anatomy of the Respiratory System
Physiology 08-09. Respiratory System. Lecture 1.
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I. Overview of Respiration •
General function: to obtain O2 for use by the body’s cells and to eliminate the CO2 the body cells produce
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Encompasses two separate but related processes: – Internal respiration • Oxidative phosphorylation – External respiration • Exchange of oxygen and carbon dioxide between atmosphere and body tissues
Physiology 08-09. Respiratory System. Lecture 1.
Internal Respiration • •
Cellular respiration Refers to metabolic processes carried out within the mitochondria, which use O2 and produce CO2, while deriving energy from nutrient molecules
Germann & Stanfield 3rd Ed., Fig 16.1 Physiology 08-09. Respiratory System. Lecture 1.
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External Respiration (4 processes) 1. Pulmonary ventilation (movement of air into lungs and out) 2. Exchange O2 & CO2 between lungs (alveoli) and blood (pulmonary capillaries) by diffusion 3. Transportation of O2 & CO2 between lungs and tissues 4. Exchange O2 & CO2 between blood and body tissues by
diffusion across systemic (tissue) capillaries
Physiology 08-09. Respiratory System. Lecture 1.
External & Internal Respiration
Sherwood 6th Ed., Fig 13-1 Physiology 08-09. Respiratory System. Lecture 1.
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Secondary functions (numerous) numerous) • Short term regulation of pH (acid-base balance) • Enabling speech, singing, and other vocalizations • Help in defense against pathogens in the airways • Removes, modifies, activates, or inactivates various materials passing through the pulmonary circulation • Eliminates heat and water • Assist venous return • Nose serves as the organ of smell Physiology 08-09. Respiratory System. Lecture 1.
II. Anatomy of the Respiratory System •
Respiratory airways leading into the lungs
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Lungs
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Structures of the Thoracic Cavity
Physiology 08-09. Respiratory System. Lecture 1.
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Upper Airways
Air passages of the head and neck
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Nasal cavity (nose)
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Oral cavity
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Pharynx (common passageway for respiratory and digestive systems) Germann & Stanfield 3rd Ed., Fig 16.2
Physiology 08-09. Respiratory System. Lecture 1.
Respiratory Airways
Conducting zone (anatomical dead space)
Airways from pharynx to lungs •Larynx •Conducting zone •Respiratory zone
Respiratory zone
Physiology 08-09. Respiratory System. Lecture 1.
Germann & Stanfield 3rd Ed., Fig 16.2
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Conducting zone (anatomical dead space)
Respiratory zone
Sherwood 6th Ed., Fig 13-2 Physiology 08-09. Respiratory System. Lecture 1.
Structures of the Conducting Zone • • • • •
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Trachea Bronchi Secondary bronchi – Right side - 3 (to 3 lobes of right lung) – Left side - 2 (to 2 lobes of left lung) Tertiary,...Bronchi – 20-23 orders of branching Up to 8 million tubules!! Bronchioles – Less than 1 mm diameter – No cartilage, risk of collapse. To prevent: walls of elastic fibers Terminal bronchioles
Physiology 08-09. Respiratory System. Lecture 1.
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Functions of the Conducting Zone •
Air passageway – 150 mL volume = dead space volume
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Increase air temperature to body temperature
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Humidify air
Epithelium of the Conducting Zone • •
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Goblet cells – secret mucus and traps foreign particles Ciliated cells – propel the mucus up the glotis to be swallowed or expelled Process: Mucus escalator Germann & Stanfield 2nd Ed., Figure 16.4a
Physiology 08-09. Respiratory System. Lecture 1.
Structures of the Respiratory Zone •
Respiratory bronchioles
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Alveolar ducts
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Alveolar sacs
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Alveoli
Germann & Stanfield 3rd Ed., Fig 16.5 Physiology 08-09. Respiratory System. Lecture 1.
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Function of the Respiratory Zone • Exchange of gases between air and blood by diffusion
Epithelium of the Respiratory Zone • Respiratory membrane – Epithelial cells of alveoli – Endothelial cells of capillary
Physiology 08-09. Respiratory System. Lecture 1.
Germann & Stanfield 3rd Ed., Fig 16.3
Physiology 08-09. Respiratory System. Lecture 1.
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Alveoli • • • • •
Alveoli = site of gas exchange 300 million alveoli/lung (tennis court size):facilitate gas exchange. Rich blood supply- capillaries form sheet over alveoli Pores of Kohn permit airflow between adjacent alveoli (collateral ventilation) 3 cell types: –
Type I alveolar cells –
- Make up wall of alveoli, single layer epithelial cells
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Type II alveolar cells –
- Secrete surfactant - Reduces surface tension in alveolar walls - Helps prevent alveolar collapse
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Alveolar macrophages
Germann & Stanfield 3rd Ed., Fig 16.5
Removes foreign particles
Physiology 08-09. Respiratory System. Lecture 1.
Respiratory Membrane •
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Barrier for diffusion –
Alveoli: Type 1 cells + basement membrane
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Capillaries: Endothelial cells + basement membrane
0.2 microns thick
Germann & Stanfield 3rd Ed., Fig 16.5 Physiology 08-09. Respiratory System. Lecture 1.
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Chest Wall and Pleural Sac
Germann & Stanfield 3rd Ed., Fig 16.7
Physiology 08-09. Respiratory System. Lecture 1.
Pleural Sac - Pleural sac around each lung - Side attached to chest: parietal pleura - Side attached to lung: visceral pleura - Intrapleural space filled with intrapleural fluid Volume = 15 mL
Sherwood 6th Ed., Fig 13-5 Physiology 08-09. Respiratory System. Lecture 1.
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