Transcript Respiratory system

Chapter 19
Lecture
PowerPoint
Respiratory
system
Anatomy and
Physiology
D-
Chapter
19
Respiratory System
2
19.1: Introduction
• The respiratory system consists of passages that filter incoming air and transport it
into the body, into the lungs, and to the many microscopic air sacs where gases are
exchanged
• Respiration is the process of exchanging gases between the atmosphere and body
cells
• It consists of the following events:
• Ventilation
• External respiration
• Transport of gases
• Internal respiration
• Cellular respiration
3
19.2: Why We Breathe
• Respiration occurs on a macroscopic level at the organ system
• Gas exchange, oxygen and carbon dioxide, occur at the cellular and molecular levels
• Aerobic reactions of cellular respiration allow for:
• ATP production
• Carbon dioxide generation forming carbonic acid
4
19.3: Organs of the
Respiratory System
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• The organs of the respiratory system can
be divided into two tracts:
• Upper respiratory tract
• The nose
• Nasal cavity
• Sinuses
• Pharynx
• Lower respiratory tract
• Larynx
• Trachea
• Bronchial tree
• Lungs
Frontal
sinus
Nasal
cavity
Hard
palate
Soft palate
Pharynx
Nostril
Oral
cavity
Larynx
Epiglottis
Esophagus
Trachea
Bronchus
5
Right lung
Left lung
Nose
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Frontal sinus
Superior
Middle
Inferior
Nasal
conchae
Sphenoidal sinus
Nostril
Hard palate
Uvula
Tongue
Hyoid bone
Pharyngeal tonsil
Nasopharynx
Opening of auditory tube
Palatine tonsil
Oropharynx
Lingual tonsil
Epiglottis
Laryngopharynx
Larynx
Trachea
Esophagus
6
Nasal Cavity
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Nasal cavity
Mucus
Particle
Cilia
Goblet cell
Epithelial cell
(a)
(b)
b: © Biophoto Associates/Photo Researchers, Inc.
7
Sinuses
• The sinuses are air-filled spaces in the maxillary, frontal, ethmoid, and
sphenoid bones of the skull
8
19.1 Clinical Application
The Effects of Cigarette Smoking on the
Respiratory System
9
Pharynx
• The pharynx is posterior to the oral cavity and between the nasal
cavity and the larynx
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Frontal sinus
Superior
Middle
Inferior
Nasal
conchae
Sphenoidal sinus
Nostril
Hard palate
Uvula
Tongue
Hyoid bone
Pharyngeal tonsil
Nasopharynx
Opening of
auditory tube
Palatine tonsil
Oropharynx
Lingual tonsil
Epiglottis
Laryngopharynx
Larynx
Trachea
Esophagus
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Larynx
• The larynx is an enlargement in the airway
superior to the trachea and inferior to the pharynx
• It is composed of a framework of muscles and
cartilages bound by elastic tissue
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Epiglottis
Hyoid bone
False vocal cord
Glottis
True vocal
cord
(a)
Thyroid cartilage
Cuneiform cartilage
Corniculate cartilage
Arytenoid cartilage
True vocal cord
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Epiglottic cartilage
Hyoid bone
Thyroid cartilage
Cricoid cartilage
Hyoid bone
Epiglottis
False vocal cord
Thyroid cartilage
Cricoid cartilage
(b)
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Posterior portion
Thyroid cartilage
of tongue
Glottis
Cricoid cartilage
Corniculate cartilage
Trachea
(a)
False vocal cord
True vocal cord
Cuneiform cartilage
(a)
Epiglottis
Glottis
Hyoid bone
Inner lining of trachea
(b)
Epiglottic cartilage
Thyroid cartilage
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Cricoid cartilage
(b)
Trachea
(c)
c: © CNRI/PhotoTake
Trachea
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• The trachea (windpipe) is a flexible
cylindrical tube about 2.5 centimeters in
diameter and 12.5 centimeters in length
• As it extends downward anterior to the
esophagus and into the thoracic cavity, it
splits into the right and left primary
Superior (upper)
bronchi
lobe bronchus
Right primary
bronchus
Middle lobe
bronchus
Larynx
Thyroid
cartilage
Cricoid
cartilage
Trachea
Cartilaginous
ring
Carina
Left
primary
bronchus
Superior (upper)
lobe bronchus
Inferior (lower)
lobe bronchi
12
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Lumen of trachea
Hyaline cartilage
Ciliated epithelium
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Hyoid
bone
Smooth muscle
Connective tissue
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Connective
tissue
Smooth
muscle
Thyroid gland
Thyroid
cartilage
Cricoid
cartilage
Incision
Trachea
Jugular
notch
Hyaline
cartilage
Ciliated
epithelium
Lumen of
trachea
© Ed Reschke
13
Bronchial Tree
• The bronchial tree consists of
branched airways leading from
the trachea to the microscopic
air sacs in the lungs
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Larynx
Trachea
Right superior (upper) lobe
Left superior
(upper) lobe
Right primary bronchus
Secondary bronchus
Tertiary bronchus
Terminal bronchiole
Right inferior (lower) lobe
Right middle lobe
Left inferior
(lower) lobe
Respiratory bronchiole
Alveolar duct
Alveolus
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Branches of the Bronchial Tree
• The successive divisions of the branches
from the trachea to the alveoli are:
1.Right and left primary bronchi
2.Secondary or lobar bronchi
3.Tertiary or segmental bronchi
4.Intralobular bronchioles (12-14 generations)
5.Terminal bronchioles
6.Respiratory bronchioles
7.Alveolar ducts
8.Alveolar sacs
9.Alveoli
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© Ralph Hutchings/Visuals Unlimited
15
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Blood flow
Blood flow
Intralobular bronchiole
Smooth muscle
Pulmonary
venule
Pulmonary
arteriole
Blood flow
Alveolus
Pulmonary
artery
Capillary network on
surface of alveolus
Pulmonary
vein
Terminal
bronchiole
Respiratory
bronchiole
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Alveolar
duct
Alveolar
sac
Alveoli
Capillary
Simple squamous
epithelial cells
Alveolus
© McGraw-Hill Higher Education, Inc./Bob Coyle
16
The Respiratory Tubes
• The structure of the bronchus is similar to
that of the trachea, but the C-shaped
cartilaginous rings are replaced with
cartilaginous plates where the bronchus
enters the lung
• These respiratory tubes become thinner and
thinner, and the cell layers thin and change
until the alveoli is reached
• It is the alveoli that provides surface area
for gas exchange
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Blood flow
Blood flow
Venule
Arteriole
Alveolar
wall
Alveolus
Air
O2
CO2
CO2 O2
Capillary
17
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Blood vessel
Capillary
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Alveolus
Alveolus
Tissues and Organs: A Text-Atlas of Scanning Electron Microscopy, by R.G. Kessel and R.H.
Kardon. © 1979 W.H. Freeman and Company
Bronchiole
Courtesy of the American Lung Association
18
Lungs
• The right and left lungs are soft, spongy, cone-shaped organs in the thoracic cavity
• The right lung has three lobes and the left lung two lobes
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Thyroid cartilage
Cricoid cartilage
Clavicle
Trachea
Scapula
Superior (upper)
lobe of right lung
Superior (upper) lobe of left lung
Inferior (lower) lobe of left lung
Middle lobe
of right lung
Inferior (lower) lobe of right lung
Rib cartilage
Sternum
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19.2 Clinical Application
Lung Irritants
21
19.4: Breathing Mechanism
• Breathing or ventilation is the movement of air from outside of the body into the
bronchial tree and the alveoli
• The actions responsible for these air movements are inspiration, or inhalation, and
expiration, or exhalation
22
Inspiration
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• Atmospheric pressure due to the weight
of the air is the force that moves air into
the lungs
• At sea level, atmospheric pressure is
760 millimeters of mercury (mm Hg)
• Moving the plunger of a syringe causes
air to move in or out
• Air movements in and out of the lungs
occur in much the same way
Air passageway
Atmospheric pressure
of 760 mm Hg on the
outside
Atmospheric
pressure
of 760 mm Hg
on the inside
Diaphragm
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23
(a)
(b)
Inspiration
• Intra-alveolar pressure decreases to about 758mm Hg as the thoracic cavity enlarges
due to diaphragm downward movement caused by impulses carried by the phrenic
nerves
• Atmospheric pressure then forces air into the airways
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Atmospheric pressure
(760 mm Hg)
Intra-alveolar
pressure
(760 mm Hg)
Intra-alveolar
pressure
(758 mm Hg)
Diaphragm
(a)
(b)
24
Inspiration
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Sternocleidomastoid
elevates sternum
Sternum
moves
Up and out
Pectoralis minor
elevates ribs
External
intercostal
muscles pull
ribs up and out
Diaphragm
contracts
(a)
Diaphragm
contracts more
(b)
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26
Expiration
• The forces responsible for normal resting expiration come from elastic recoil of lung
tissues and from surface tension
• These factors increase the intra-alveolar pressure about 1 mm Hg above atmospheric
pressure forcing air out of the lungs
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Expiration
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Posterior internal
intercostal muscles
pull ribs down and
inward
Diaphragm
Diaphragm
Abdominal organs
recoil and press
diaphragm upward
Abdominal organs
force diaphragm
higher
Abdominal wall
muscles contract
and compress
abdominal organs
(a)
(b)
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29
Respiratory Air
Volumes and Capacities
• Different degrees of effort in breathing move different volumes of air in and out of
the lungs
• This measurement of volumes is called spirometry
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6,000
Lung volume in milliliters (mL)
5,000
Inspiratory
reserve volume
Vital
capacity
4,000
Inspiratory
capacity
Total lung
capacity
3,000
2,000
1,000
0
Tidal
volume
Residual
volume
Expiratory
reserve volume
Functional
residual
capacity
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31
Alveolar Ventilation
• The volume of new atmospheric air moved into the respiratory passages each
minute is minute ventilation
• It equals the tidal volume multiplied by the breathing rate
• Much of the new air remains in the physiologic dead space
• The tidal volume minus the physiologic dead space then multiplied by breathing
rate is the alveolar ventilation rate
• This is the volume of air that reaches the alveoli
• This impacts the concentrations of oxygen and carbon dioxide in the alveoli
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Nonrespiratory Air Movements
• Air movements other than breathing are called nonrespiratory movements
• They clear air passages, as in coughing and sneezing, or express emotions, as in
laughing and crying
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34
19.3 Clinical Application
Respiratory Disorders That Decrease
Ventilation: Bronchial Asthma and
Emphysema
35
19.5: Control of Breathing
• Normal breathing is a rhythmic, involuntary act that continues when a person is
unconscious
• Respiratory muscles can be controlled as well voluntarily
36
Respiratory Areas
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• Groups of neurons in the brainstem comprise
the respiratory areas that control breathing
• Impulses travel on cranial nerves and spinal
nerves, causing inspiration and expiration
• Respiratory areas also adjust the rate and
Pontine respiratory
group
depth of breathing
Pons
Medulla oblongata
• The respiratory areas include:
Ventral respiratory group
• Respiratory center of the medulla
Dorsal respiratory group
• Respiratory group of the pons
Midbrain
Fourth
ventricle
Medullary
respiratory
center
Internal (expiratory)
intercostal muscles
External (inspiratory)
intercostal muscles
Diaphragm
37
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Respiratory areas
Pontine respiratory
group
Medullary respiratory center
Ventral
respiratory
group
Dorsal
respiratory
group
Nerve impulses
Nerve impulses
Respiratory muscles
Basic rhythm
of breathing
Forceful breathing
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Factors Affecting Breathing
• A number of factors affect breathing rate
and depth including:
• Partial pressure of oxygen (Po2)
• Partial pressure of carbon dioxide
(Pco2)
• Degree of stretch of lung tissue
• Emotional state
• Level of physical activity
• Receptors involved include
mechanoreceptors and central and
peripheral chemoreceptors
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Medulla oblongata
Sensory nerve
(branch of
glossopharyngeal
nerve)
Sensory nerve
(branch of vagus nerve)
Aorta
Carotid bodies
Common carotid
artery
Aortic bodies
Heart
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Factors Affecting Breathing
• Changes in blood pH, O2 and
CO2 concentration stimulates
chemoreceptors
Sensory pathway
• Motor impulses can travel
Vagus nerve
from the respiratory center
to the diaphragm and external Phrenic nerve
intercostal muscles
• Contraction of these muscles Stretch receptors
Lung
causes the lungs to expand
stimulating mechanoreceptors in
the lungs
• Inhibitory impulses from the
mechanoreceptors back to the
respiratory center prevent
overinflation of the lungs
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Respiratory center
Spinal cord
–
–
Motor pathways
External intercostal
muscles
Intercostal nerve
Rib
Diaphragm
40
41
19.4 Clinical Application
Exercise and Breathing
42
19.6: Alveolar Gas Exchanges
• The alveoli are the sites of the vital process of gas exchange between the air and
the blood
43
Alveoli
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44
Courtesy of the American Lung Association
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Type I (squamous epithelial) cell
of alveolar wall
Type II (surfactantsecreting) cell
Fluid with
surfactant
Macrophage
Alveolus
Respiratory
membrane
Cell of
capillary wall
Capillary lumen
Alveolar fluid (with surfactant)
Alveolus
Diffusion of O2
Alveolar epithelium
Basement membrane of
alveolar epithelium
Interstitial space
Respiratory
membrane
Basement membrane of
capillary endothelium
Diffusion of CO2
Capillary endothelium
Capillary
Red blood cell
45
Respiratory Membrane
• Part of the wall of an alveolus is made up of cells (type II cells) that secrete
pulmonary surfactant
• The bulk of the wall of an alveolus consists of a layer of simple squamous
epithelium (type I cells)
• Both of these layers make up the respiratory membrane through which gas
exchange takes place
46
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EP
AS
BM
RBC
AS
IS
47
© Imagingbody.com
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Alveolus
Diffusion of CO2
Alveolar
wall
PCO = 40 mm Hg
2
PCO = 45 mm Hg
2
PO = 104 mm Hg
2
Diffusion of O2
PO = 40 mm Hg
2
Blood flow
(from body
tissues)
Blood flow
(to body
tissues)
Capillary
PCO = 40 mm Hg
2
PO = 104 mm Hg
2
48
Diffusion Through the
Respiratory Membrane
• Molecules diffuse from regions where they are in higher concentration toward
regions where they are in lower concentration
• It is important to know the concentration gradient
• In respiration, think in terms of gas partial pressures
• Gases diffuse from areas of higher partial pressure to areas of lower partial pressure
• The respiratory membrane is normally thin and gas exchange is rapid
• Increased diffusion is favored with more surface area, shorter distance, greater
solubility of gases and a steeper partial pressure gradient
• Decreased diffusion occurs from decreased surface area
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19.5 Clinical Application
Effects of High Altitude
50
19.6 Clinical Application
Disorders That Impair Gas Exchange:
Pneumonia, Tuberculosis, and Adult
Respiratory Distress Syndrome
51
19.7: Gas Transport
• Blood transports O2 and CO2 between the lungs and the body cells
• As the gases enter the blood, they dissolve in the plasma or chemically combine
with other atoms or molecules
52
Oxygen Transport
• Almost all oxygen carried in the blood is bound to the protein hemoglobin in the
form of oxyhemoglobin
• Chemical bonds between O2 and hemoglobin are relatively unstable
• Oxyhemoglobin releases O2 into the body cells
• About 75% of the O2 remains bound to hemoglobin in the venous blood ensuring
safe CO2 levels and thereby pH
53
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Alveolus
Alveolar
wall
Capillary
Hemoglobin
molecules
Oxygen
molecules
Diffusion
of oxygen
Hemoglobin
molecules
Blood
PO2 = 40 mm Hg
Blood flow
(to lungs)
Oxyhemoglobin
molecule
Blood flow
(from body
tissues)
(a)
Blood
PO2 = 95 mm Hg
Diffusion
of oxygen
Tissue cells
Tissue
PO = 40 mm Hg
2
(b)
54
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100
% saturation of hemoglobin
90
80
70
60
50
40
30
20
10
0
10
20
30
40
50
60 70 80
PO2(mm Hg)
90 100 110 120 130 140
Oxyhemoglobin dissociation at 38°C
55
• The amount of oxygen released from oxyhemoglobin increases with:
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100
80
70
PCO2 =
20 mm Hg
40 mm Hg
80 mm Hg
60
50
40
30
20
10
10 20 30 40 50 60 70 80 90 100 110 120 130 140
PO2 (mm Hg)
Oxyhemoglobin dissociation at 38°C
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100
90
80
70
pH =
7.6
7.4
7.2
60
50
40
30
20
10
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0
10
20
30
40
50
60
70
80
90
100 110 120 130 140 100
PO2 (mm Hg)
90
Oxyhemoglobin dissociation at 38°C
% saturation of hemoglobin
0
% saturation of hemoglobin
% saturation of hemoglobin
90
80
70
60
50
40
30
20
56
10
0
10 20
30
40 50
60 70 80 90 100 110 120 130 140
PO2 (mm Hg)
Oxyhemoglobin dissociation at various temperatures
Carbon Dioxide Transport
• Blood flowing through capillaries gains CO2 because the tissues have a high Pco2
• The CO2 is transported to the lungs in one of three forms:
• As CO2 dissolved in plasma
• As part of a compound with hemoglobin
• As part of a bicarbonate ion
57
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Tissue cell
Tissue
PCO2 = 45 mm Hg
Cellular CO2
CO2 dissolved
in plasma
CO2 + H2O
PCO2 = 40 mm Hg
Blood
flow from
systemic
arteriole
CO2 combined with
hemoglobin to form
carbaminohemoglobin
HCO3-
Plasma
Red blood cell
H2CO3
PCO2 = 45 mm Hg
HCO3- + H+
+
H combines
with hemoglobin
Blood
flow to
systemic
venule
Capillary wall
58
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Capillary wall
Red blood cell
Plasma
ClHCO3-
Cl-
HCO3HCO3Cl-
59
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Alveolus
PCO2 = 40 mm Hg
CO2
CO2dissolved
in plasma
CO2+ H2O
PCO2 = 45 mm Hg
Blood flow
from pulmonary
arteriole
CO2
Alveolar wall
HCO3-
Plasma
HCO3-+
H2CO3
CO2
Carbaminohemoglobin
H+
H+ released
from hemoglobin
Red blood cell
CO2 + hemoglobin
PCO2 = 40 mm Hg
Blood
flow to
pulmonary
venule
Capillary wall
60
61
19.8: Lifespan Changes
• Lifespan changes reflect an accumulation of environmental influences and the
effects of aging in other organ systems, and may include:
• The cilia become less active
• Mucous thickening
• Swallowing, gagging, and coughing reflexes slowing
• Macrophages in the lungs lose efficiency
• An increased susceptibility to respiratory infections
• A “barrel chest” may develop
• Bronchial walls thin and collapse
• Dead space increasing
62
Important Points in Chapter 19:
Outcomes to be Assessed
19.1: Introduction
 Identify the general functions of the respiratory system.
19.2: Why We Breathe
 Explain why respiration is necessary for cellular survival.
19.3: Organs of the Respiratory System
 Name and describe the locations of the organs of the respiratory
system.
 Describe the functions of each organ of the respiratory system.
19.4: Breathing Mechanism
 Explain how inspiration and expiration are accomplished.
 Name and define each of the respiratory air volumes and capacities.
63
Important Points in Chapter 19:
Outcomes to be Assessed
 Calculate the alveolar ventilation rate.
 List several non-respiratory air movements and explain how each
occurs.
19.5: Control of Breathing
 Locate the respiratory areas and explain control of normal breathing.
 Discuss how various factors affect breathing.
19.6: Alveolar Gas Exchanges
 Define partial pressure and explain its importance in diffusion of gases.
 Describe gas exchange in the pulmonary and systemic circuits.
64
Important Points in Chapter 19:
Outcomes to be Assessed
 Describe the structure and function of the respiratory membrane.
19.7: Gas Transport
 Explain how the blood transports oxygen and carbon dioxide.
19.8: Lifespan Changes
 Describe the effects of aging on the respiratory system.
65