Structure and function of pulmonary system part 1 Flashcards
Ventilation
movement air in and out lungs
Diffusion
movement of gases between air spaces in the lungs and the bloodstream
Perfusion
Movement of blood into and out of the capillary beds of the lungs to body organs and tissues
Pulmonary system
carries out the first two processes (ventilation, diffusion)
Cardiovascular system
carries out the third process (perfusion)
Two lobes
- Right lung (three lobes)
- Left lung (two lobes)
Diaphragm
involved in ventilation
-Dome-shaped muscle separates the thoracic and abdominal cavities
Mediastinum
Space between the lungs, containing the heart, great vessels and esophagus
Carina
Ridge where trachea divides
Hila
Right and left bronchi enter the lungs, along w/ lymph vessels
Goblet cells
produce mucus
Cilia
hairlike structures
Gas exchange airways:Acinus
Respiratory bronchioles, alveolar ducts, alveoli-primary
Alveoli
Primary gas exchange
-O2 enters the blood and CO2 is removed
Pores of kohn
-permits air to pass through septa from alveolis to alveolis-this allows air to move through one alveolar sac to the next
Epithelial cells
- Type 1-alveolar structure
- Type 2-surfactant production
Surfactant
lipoprotein coats inner surface of alveoli and helps facilitate expansion during inspiration and decreases alveolar surface tension at the end of expiration
Alveolar macrophages
ingest foreign material and remove it through the lymphatic system
Pulmonary and bronchial circulation
- facilitates gas exchange
- delivers nutrients to lung tissues
- acts as a blood reservoir for the LV
- Serves as filtering system that removes clots, air, and other debris from circulation
Pulmonary artery
-divides and enters the lung as the hilus
Bronchus
each bronchus and bronchiole has an accompanying artery or arteriole
-Lungs are vascular organs
Pulmonary capillaries
surround the acinus
Alveolocapillary membrane
- formed by shared alveolar and capillary walls
- Gas exchange occurs here
Control of pulmonary circulation
-Most important cause of pulmonary artery constriction: low alveolar partial pressure oxygen (PaO2)
Pulmonary artery constriction
-Acidemia and inflammatory mediators
Vasoconstriction
caused by alveolar and pulmonary venous hypoxia: hypoxic pulmonary vasoconstriction
Thoracic cavity
contained by the chest wall and encases the lungs
Pleura
- Serous membrane
- Adheres firmly to the lungs
- Firmly attaches to the chest wall
Visceral pleura
membrane covering lungs
Parietal pleura
lining the thoracic cavity
Pleura
Area between the two pleura
- Fluid lubricates the pleural surfaces, allowing the two layers to slide over each other w/out separating
- Pressure in the pleural space: negative or subatmospheric (-4 to -10 mm Hg)
Minute volume
ventilatory rate sis multiplied by the volume of air per breath
Respiratory center
- located in brainstem
- Dorsal respiratory group: sets the basic automatic rhythm
- Ventral respiratory group
Ventral respiratory group
becomes active when increased ventilatory effort is required
Dorsal respiratory group
receives impulses from peripheral chemoreceptors in the carotid and aortic bodies: detects the Paco2 and the amount of oxygen in the arterial blood.
Pneumotaxic and apneustic centers
located in pons
modifiers of the inspiratory and rate are established by the medullary centers
Lung receptors
- Irritant receptors
- Stretch receptors
- Juxtapulmonary capillary J receptors
Irritant receptors
-when stimulated cough, bronchoconstriction and increase respiratory rate
Stretch receptors
protect against excess lung inflation
-Decrease RR and volume
Juxtapulmonary J receptors
are sensitive to increased pulmonary pressure
Central chemoreceptors
- Reflects Paco2
- Stimulated by hyrogen in then CSF
- Increased the RR and depth
Peripheral chemorecptors
- Located in the aorta and carotid bodies
- Stimulated by the hypoxemia pao2
- responsible for all the increase in ventilation that occurs in response to the arterial hypoxemia
Major muscles of inspiration
-Diaphragm and external intercostal muscles
Accessory muscles of inspiration
-Sternocleidomastoid and scalene muscles
accessory muscles of expiration
no major muscles
-Abdominal and internal intercostal muscles
Compliance
- Measures lung and chest wall distensibility
- represents the relative
- Low: Increase work of inspiration (stiff lungs)
- High: increased work of expiration (easy to inflate has lost some elastic recoil)
Scleroderma
Hardening of skin-hard to expand lungs
Gas transport
1-ventilation of lungs
2-diffusion of O2 from the alveoli into the capillary blood
3-Perfusion of systemic capillaries w/ oxygenated blood
4-diffusion of O2 from systemic capillaries into the cells
-Diffusion of CO2 occurs in the reverse order
Effective gas exchange-
-Needs approximately even distribution of gas (ventilation) and blood (perfusion) in all portions of the lungs: V/Q shunt
Ventilation-perfusion ratio
- Perfusion exceeds ventilation in the bases of the lungs
- Ventilation exceeds perfusion in the apices of the lungs
Oxyhemoglobin
- Hgb molecules bind w/ O2
- Shift to right hgb decreased affinity for O2 or an increase in the ease w/ oxyhgb dissociates and O2 moves into the cells (acidosis, hypercapnia and hyperthermia)
- Shift to left: hgb increased affinity for O2. Promotes association in the lungs and inhibits dissociated in the tissues (alkalosis, hypocapnia, hypothermia)
Carbon dioxide
- Dissolved in plasma
- Bicarbonate
- Carbamino compounds
- haldane effect
Spirometery
-Measures volume and flow rate during forced expiration
Diffusion capactiy
measure gas diffusion at the alveolocapillary membrane
