Download 1 Organisation of resp syst

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:
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Mon, Jan 19 - Organization of the respiratory system
•
Wed, Jan 21 - Lung mechanics
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Thur,
Thur, Jan 22 - NO LECTURE
•
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.
1
Before we start…
start…
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The respiratory system:
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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.
2
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
6
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
•
Humidify air
Epithelium of the Conducting Zone
•
•
•
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
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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
–
Type II alveolar cells –
- Secrete surfactant
- Reduces surface tension in alveolar walls
- Helps prevent alveolar collapse
–
Alveolar macrophages
Germann & Stanfield 3rd Ed., Fig 16.5
Removes foreign particles
Physiology 08-09. Respiratory System. Lecture 1.
Respiratory Membrane
•
•
Barrier for diffusion
–
Alveoli: Type 1 cells + basement membrane
–
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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