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function of respiration
gas exchange. inspiration: breath in O2. expiration: breath out CO2. gas is carried by blood and both the respiratory and the cardiovascular system supply cell with O2 and rid of CO2.
function of nasal septum and nasal turbinates.
air filter. block out dust.
how does air flow?
through the nose, pass the nosal septum and turbinates, through the pharynx and larynx, reach trachea and bronchi. three main lobar bronchi on right lung and 2 bronchi on left lung.
what does the lungs and the airways share with the chest cavity
the heart, the great vessels, and the esophagus.
subdivisions of the conducting airways and terminal respiratory units.
- 1. trachea
- 2. bronchi
- 16. bronchioles
- 6*10^4. terminal bronchioles
- 5*10^5. respiratory bronchioles
- --. alveolar ducts
- 8*10^6. alveolar sacs
- parietal pleura: attached to thoracic cage.
- viscerla pleura: attached to lung surface.
- pressure is negative.
conducting and respiratory zones
- conducting: airways from mouth to terminal bronchioles. no gas exchange. anatomical dead space.
- respiratory: terminal bronchioles into respiratory bronchioles. site of gas exchange. most of lungs.
four functions of conducting airways.
- 1. defense against bacteria and foreign particles. mucous can trap them and cilia sweep the mucous up into the pharynx. mucociliary defense system
- 2. warm and moisten inhaled air.
- 3. produce sound and speech by passing air over the vocal cords.
- 4. regulate air flow using smooth muscle contraction or relaxing. alter resistance to air flow.
there are roughly 300 million alveoli in human lungs and each alveolus may be associated iwth as many as 1000 capillaries.
- 1. pulmonary: venous blood from diff organs to lungs, get oxygenated and goes to the left heart and to the rest of the body.
- 2. bronchial: give oxygenated blood from systemic circulation to tracheobronchial tree (oxygenate the airways).
- pulmonary artery from the right ventricle (collected from rest of body) go to the pulmonary capillaries, reach the alveoli and get oxygenated.
- the pulmonary arteries supply wiht blood all capillaries within the alveolar walls.
- oxygenated blood goes to the left hear via the pulmonary veins.
- bronchial arteries from aorta supply the airway walls.
- part of systemic.
- venous blood from terminal bronchiole mix with the oxygenated blood in the pulmonary vein (goes to left heart).
Alveolar cell types
- 1. epithelial type 1 and 2.
- - type 1 function unknown, type 2 produce pulmonary surfactant (decrease surface tension of alveoli)
- -together form a complete epithelial layer
- 2. endothelial cells
- -walls of pulmonary capillaries (0.1 micron).
- 3. alveolar macrophages
- -defense system after mucociliary system.
inspiratory respiratory muscles
- 1. principle: external intercostals, parasternal intercartilaginous muscles; both elevate rigs, disphragm; dome descends.
- 2. accessory: sternocleidomastoid; elevate sternum, scalenus (anterior, middle, posterior); elevate and fix upper ribs. useful in high levels of ventilation. contractions seen in disease.
- -innervated by phrenic nerves from cervical seg 3-5.
what increase the longitudinal dimension of chest
diaphragm descending, and elevating lower ribs.
expiratory respiratory muscles
- 1. quiet: pass recoil of lungs.
- 2. active: intercostals, except parasternal intercartilaginous mucles, abdominal muscles, rectus abdominis, external oblique, internal oblique, transversus abdominis. exercise, depress ribs and compress abdominal content.
- -pull down the anterior part of lower chest. force diaphram upwards.
- -forced maximal contraction agsint a close glottis result in increase in pressure in thoracic cage and abdomen. decrease venous return to heart, decrease cardiac output.
anterior-posterior and transverse dimensions of the chest
elevating the ribs
anterior-posterior and longitudinal dimensions of the chest
elevate the sternum, slightly enlarge
measuring lung volumes
- -measure tidal volume, vital capacity, inspiratory capacity, expiratory reserve volume and inspiratory reserve volume.
Measurement of FRC
- -use helium dilution. c1v1=c2v2.
- -first subject has to breath to FRC, then equilibrate.
Equation for minute ventilation
Physiological dead space (Vd)
- sum of alveolar and anatomical dead space.
- the difference between minute and alveolar ventilation is the dead space ventilation that is wasted.
Types of alveolar ventilation (ventilation has to be considered with respect to metabolism).
- normal: Va matches CO2, keep PaCO2 at constant level.
- hyperventilation: more O2 supply, more CO2 removed than necessary. PaO2 rises, PaCO2 decreases.
- hypoventilation: less O2 supply, less CO2 removal, PaO2 falls and PaCO2 rises. severe disorders of the lungs or damage to respiratory muscles. injured chest cage, collapsed lung and depressed central nervous system.
law of diffusion. you know what this is.
Which is more soluble between CO2 and O2?
CO2 is more soluble than O2 and it diffuses 20 times faster.
- blood pressure in the pulmonary circulation is lower than in the systemic circulation.
- walls of the pulmonary capillaries are thinner than those of similar vessels in the systemic circulation.
- blood pressure in the pulmonary circulation falls gradually during disastole to a low of about 8 mmHg as blood flows through the pulmonary capillaries.
- mean pulmonary arterial pressure is 15 mmHg while the left atrial pressure is about 5 mmHg.
pulmonary resistance is only 1/10 that of systemic circulation. thin walls.