Respiratory System Lecture 1 Flashcards
What are the six functions of the respiratory system?
- Provide O2
- Eliminate CO2
- Form speech sounds (phonation)
- Defend against microbes (host defence)
- Trap and dissolve blood clots arising from systemic (usually leg) veins
- Modulate concentration of biologically active molecules
What is each exponential branching of the airway tree called?
A generation
How many lobes does the left lung have?
2, there is no middle lobe.
Where does gas exchange take place?
In the aveoli
True/False. A very dense blood supply is essential in the blood vessels surrounding the airways.
True
What does the conducting zone do?
Conducts air to the respiratory zone.
What does the respiratory zone do?
Gas exchange.
What is the last series of airway division called?
The terminal bronchiole.
What is the very last part of the physiological conducting zone?
The respiratory bronchiole.
Where does gas exchange take place?
The alveoli in the respiratory zone.
What is the main difference between a terminal and respiratory bronchiole?
The absence or presence of alveoli (respiratory bronchiole has alveoli)
Describe the surface for gas exchange?
Large surface area, but very thin distance to transverse.
What is the purpose of type ii alveolar cells?
These cells only cover a small fraction of the alveolar surface area, and serve to secrete pulmonary surfactant, which decreases surface tension within the alveoli. They can divide to make more type i cells. They are found in the blood-air barrier.
What is the purpose of type i alveolar cells?
These flat cells are for structural support, covering the majority of the alveolar surface. They are extremely thin to enable rapid gas exchange.
What are alveolar cells (type i and ii)?
Cells that line the alveoli of the lungs.
Where is the blood-air barrier found?
In the gas exchange region of the lungs
What does the blood-air barrier do?
Prevents blood from entering the alveoli and air bubbles from entering the blood.
Where is the visceral pleura found?
Immediately surrounding the lungs.
Where is the parietal pleura found?
Attached to the interior thoracic wall and diaphragm.
Where is the intrapleural fluid found?
Between the two pleural surfaces, lubricating them as they slide over each other during brathing.
What is intrapleural pressure?
Pressure in the intrapleural fluid, which is less than atmospheric. This is because the two pleural membranes pull in opposite directions from each other, decreasing the pressure.
What is tidal breathing?
Normal, daily, comfortable breaths.
What structures are at work during inspiration of normal, quiet breathing?
The diaphragm (domes descend, increasing longitudinal dimension of chest and elevating lower ribs) and external intercostal muscles (elevate ribs).
What additional structures are at work for inspiration during exercise?
Accessory muscles of inspiration are recruited to further lift the chest - the scalene muscles (elevate and fix upper ribs) and sternomastoids (elevates sternum).
What accessory muscles are recruited for expiration during exercise?
Internal intercostals (depress ribs) and abdominal muscles (depress lower ribs, compress abdominal contents).
What muscles are at work during expiration of normal, quiet breathing?
Expiration is passive!
What is the main muscle used for respiration?
The diaphragm.
Approximately how many generations of physiological zones of airways are there before the alveolar ducts?
20
What are the three conducting airways?
Trachea, bronchi, nonrespiratory bronchioles
What are the three components of the respiratory unit?
Respiratory bronchioles, alveolar ducts, and alveolar sacs.
What is the general trend in size as the airways reach successive generations?
Get smaller and smaller.
Which physiological zones have cilia?
Trachea, bronchi, bronchioles, and some for respiratory bronchioles.
Which physiological zones have smooth muscle?
Trachea, bronchi, bronchioles, and some in the respiratory bronchioles and alveolar ducts.
Which physiological zones have cartilage?
Trachea and some for the bronchi.
What are the four functions of the conducting zone?
- Warms and humidifies air
- Flow of air past the vocal cords causes them to vibrate and produce sounds.
- Primary host defence.
- Provides a low-resistance pathway for air flow. Resistance is regulated by changes in contraction of airway smooth muscle. Smooth muscle may contract or relax to alter resistance to air flow.
Describe the clearance of inhaled particles as part of the non-respiratory functions of the lung.
- nasopharnyx - gets stuck in the mucous of the nose
- mucocillary system- bronchi, stick to mucous and transported out by cilia in one direction
- alveolar macrophages - engulf particles to kill bacteria directly and move particles into lymphatic system
What are the submucosal glands?
Secrete mucous cells
What is the respiratory system?
Lungs, airways (tubes) leading to them, and the chest structures responsible for moving air in and out
What is the conducting zone?
The trachea, bronchi, and terminal bronchioles (no gas exchange)
Describe the volume of the conducting zone?
150mL
What is the respiratory zone?
Alveoli and structures to which alveoli are attached (gas exchange takes place)
What are the alveoli lined by?
Type i and type ii cells
What do the pleural membranes cover?
The lungs and interior of the thorax
What are the non-respiratory functions of the lung?
Metabolic and host defence
What allows good gas exchange?
Perfusion of blood that is well matched to ventilation of air in and out of the lungs.
What types of substances are found in the pulmonary circulation? What happens to them?
Peptides, amines, and arachidonic acid metabolites.
