Transcript Chapter 53 - Respiratory Therapy Files

Chapter 53
Cardiopulmonary Anatomy
and Physiology
Objectives
1. Describe the gross and functional anatomy of
the heart and circulatory system.
2. Describe the gross and functional anatomy of
the respiratory system.
3. Describe the anatomy of the upper airway.
4. Describe the anatomy of the tracheobronchial
tree.
5. Discuss the relationship between the bony
elements of the thorax.
Objectives
6. Compare the roles of the diaphragm, accessory
inspiratory muscles, and abdominal muscles.
7. Discuss the pulmonary and bronchial
circulations.
8. Describe how breathing is controlled by the pons
and medulla.
9. Describe innervation of the lungs.
10. Describe the visceral pleura, parietal pleura, and
pleural space.
Objectives
11. Describe the anatomy of the mediastinum.
12. Describe the mucociliary apparatus.
13. Describe the smooth muscle function of the
airways and the pulmonary circulation.
14. Compare macrophages and dendritic cells
found within the respiratory system.
15. Compare alveolar type I and type II cells.
Objectives
16. Describe the interstitial space within the
lungs.
17. Describe the role of airway resistance and
respiratory system compliance on the
pressures generated during the respiratory
cycle.
18. Compare the distribution of ventilation and
blood flow within the lungs.
Objectives
19. Discuss the importance of the ventilation
perfusion ratio.
20. Describe oxygen uptake from the lungs.
21. State why diffusion capacity of the lungs is
evaluated.
The Heart
• The major function of the heart is to generate
pressure that will propel blood through the lungs
and the systemic circulation.
• The muscular structure consists of three parts:
o Epicardium: a thin membrane that lines the
outside of the heart.
o Myocardium: consists of cardiac muscle, serving
as the primary pumping function of the heart.
o Endocardium: the innermost lining of the heart
composed of endothelial cells.
The Heart
• The heart is considered a single pump.
• It functions as two pumps involving flow
through four chambers: the right atrium and
ventricle and the left atrium and ventricle.
• The electrical conduction system of the heart
consists of specialized cells and the major
pacemaker of the heart is the sinoatrial (SA)
node.
FIGURE 53–1 The heart and great vessels presented in a
medial plane that slices the structures in half.
Circulatory System
• The circulatory system provides nutrients,
particularly oxygen, to all of the cells in the
body.
• The arterial system is a branching series of
vessels that carries blood from the heart to the
capillary beds and subsequently to the cells of
the lungs and body.
Circulatory System
• Gross Anatomy of the Circulatory System
o The heart muscle
o Valves, chambers, and pressures
o Arteries, veins, and capillaries
o Conduction system
o Coronary circulation
o Innervation
Circulatory System
• Arteries are thicker and flexible to withstand the
higher pressures required to drive blood to and
through major organs.
• Veins are thinner; their role is more passive as
conduits for returning blood to the heart.
• The arterial system is vulnerable to disease as a
result of consuming substances (high-cholesterol
foods or cigarette smoke) that are associated with
the formation of plaques on the inner walls of
major arteries.
Circulatory System
• Arteries of the body tend to be deeper (see
Figure 53-6).
• Normal arterial pressure is relatively uniform
at about 120/80 mm Hg.
• Occlusions or strictures of the coronary
arteries are extremely dangerous.
• The veins of the body tend to be near the
surface of the skin and are more numerous
than arteries (see Figure 53-7).
FIGURE 53–6
Arteries.
FIGURE 53–7
Veins.
Gross Anatomy of the
Respiratory System
• The respiratory system can be divided into the
upper and lower respiratory tracts.
• The upper respiratory system (tract) includes
the nasal cavity, paranasal sinus, pharynx,
tongue, epiglottis, soft and hard palates, oral
cavities, laryngopharynx, and portions of the
trachea.
• The lower respiratory tract extends from the
trachea to the alveoli.
FIGUR
E 53–8
Anatomy
of the
upper
airway.
Anatomy of the Thorax
• The thorax contains an infrastructure
composed of the chest wall and the vertebrae
within which major organs reside.
• The chest wall (i.e., skin, ribs, intercostal
muscles) protects the lungs from injury.
• Thoracic muscles such as the diaphragm
perform the work of breathing.
Anatomy of the Thorax
• The thorax has three regions:
o The mediastinum
o A right pleural cavity
o A left pleural cavity
• The mediastinum contains major blood
vessels, the esophagus, and the heart.
• The pleural cavities contain the lungs.
Anatomy of the Thorax
• The bony elements of the thorax include the:
o Sternum
o Ribs
o Thoracic vertebrae
o Clavicles
o Scapulae
Anatomy of the Thorax
• The diaphragm and external intercostals are
the primary muscles of inspiration.
• During exhalation, the elastic recoil of the
lungs and relaxation of the diaphragm allow
the lungs to return to their end-expiratory
volume and position.
• The diaphragm is a large muscle that provides
the primary force for the work of breathing.
Anatomy of the Thorax
• Accessory muscles are coordinated with
diaphragm movement during inspiration.
• The lungs are cone shaped, with a broad and
concave base surrounded by the thoracic ribs
and diaphragm.
• There are five lobes and 18 lung segments
between the right and left lungs.
• See Table 53–1: Lobes and Segments of the
Lungs.
Anatomy of the Thorax
• The lungs consist of two major anatomic
divisions: the airways and the parenchyma.
• Within the lung parenchyma, adults have
approximately 300 million alveoli.
• The lungs and their covering, the pleura, are
well endowed with lymphatic circulation and
lymph nodes.
Anatomy of the Thorax
• The lungs are well perfused, receiving nearly
all of the cardiac output.
• The pulmonary arteries originate from the right
ventricle and deliver deoxygenated blood to
the lungs and the visceral pleura.
• Respiratory centers in the midbrain control
ventilation in response to emotional, physical,
and chemical changes or stimuli.
Anatomy of the Thorax
• The nerve supply of the lung involves all the
organ’s components—the airways,
parenchyma, and vasculature.
• Innervation of the Lungs
o Parasympathetic (cholinergic)
o Sympathetic (adrenergic)
Anatomy of the Thorax
• Reflexes that influence breathing response
include:
o Hering Breuer (inflation)
o Irritant
o Peripheral proprioceptor
o Hypothalamic control
o Cortical controls
Anatomy of the Thorax
• Each lung is covered with a lining, the visceral
pleura, which covers the surface of the lungs,
extending into the fissures between the lobes.
• The chest wall is lined by the parietal pleura.
• The pleural space is a cavity containing a small
amount of thin fluid.
Anatomy of the Thorax
• The fluid in the pleural space is vital in
allowing frictionless sliding between the
visceral and parietal pleurae.
• The mediastinum is the area between the two
pleural sacs and all structures within the
thorax, except the lungs and pleurae, are
located in the mediastinum.
Microanatomy of the
Respiratory System
• The main function of the lung is to provide
adequate gas exchange.
• As air moves in and out of the lungs, gas
exchange in the alveoli maintains adequate
homeostasis in the body.
• Responses to foreign body inhalation can lead to
respiratory compromise.
• The body reacts to these exposures by coughing,
sneezing, bronchoconstriction, and increasing
mucus production.
Microanatomy of the
Respiratory System
• It is important for the mucociliary apparatus to
maintain a fluid homeostasis.
• Mucociliary apparatus contains a mucous layer
and cilia that move the mucous layer.
• Both the airways and pulmonary vasculature
are lined with smooth muscle cells and smooth
muscle control is involuntary.
Microanatomy of the
Respiratory System
• Mast cells are cells that release mediators.
• Dendrites are antigen presenting cells.
• Macrophages are phagocytic cells.
• Alveolar Cells
o Type I: cover greatest surface area
o Type II: produce surfactant
• Absence of pulmonary surfactant can cause
collapse of the alveoli, resulting in atelectasis.
Microanatomy of the
Respiratory System
• The pulmonary interstitium is the space
between the alveolar epithelial and the
endothelial cells lining the vasculature.
• The interstitium serves as mechanical support,
containing various cell types associated with
the maintenance of fluid balance in the lung.
• In pulmonary interstitial lung diseases there is
an increase in the number of cells that reside in
the interstitium increasing its thickness.
Functional Characteristics of
the Respiratory System
• The major purpose of the lungs and the chest wall
is to generate pressure gradients to allow air to
flow into and from the lung.
• Two mechanical parameters, compliance and
resistance, can be calculated when the pressure,
volume, and flow characteristics of the respiratory
system are known.
• Compliance is determined by measuring the
change in lung volume divided by the
corresponding change in pressure.
Functional Characteristics of
the Respiratory System
• The resistance to airflow is associated with the
size and patency of the airways as well as the
relative turbulence of airflow.
• An inspired tidal volume is distributed to the
conducting airways and alveoli.
• The volume of the conducting airways does
not participate in gas exchange and is called
dead space volume.
Functional Characteristics of
the Respiratory System
• For optimal gas exchange, ventilation must be
distributed to match perfusion throughout the
lungs.
• Gas exchange in the lung depends not only on
the distribution of ventilation but also on the
distribution of pulmonary blood flow as well
as whether ventilation and perfusion of various
lung units are matched.
Functional Characteristics of
the Respiratory System
• The ventilation-perfusion ratio ideally should
be nearly equal to ensure the most effective
gas exchange.
• Another factor that influences gas exchange is
the time that a red blood cell (RBC) needs to
transit the pulmonary capillary.