Lecture 1-EXAM 4 (respiratory) Flashcards
what are the reasons why we breath? (3)
O2 goes to electron transport chain to make ATP
In a normal person, what are the volumes of tidal volume, dead space and alveolar ventilation?
- TV: 500ml
- Dead: 150 ml (no gas exchange)
- Alv: 350ml (where gas exchange happens)
What are the factors that affects gas exchange? (3)
- Surface area: alveoli has a lot of SA that is important for exchange
- Respiratory membrane
- Blood supply
Notice: There is a short diffusion distance
As we move down the resp. trees in the lungs, what happens to the diameter, cilia, goblet cells, cartilage and smooth muscle?
Going down the lung braches:
* Decreases in: Diameter (smallest being alveolar sac), cilia (for propeling dust/debris out), cartilage, goblet cells
* Increases in: Smooth muscle (the most being in bronchioles and terminal brochioles)
* Smooth muscle replaces cartilage
What is the size of bronchioles?
0.5-1mm
What muscles are for normal (eupneic) inspiration and expiration?
- Inspiration: External intercostals (elevates ribs 2-12 widen thoracic cavity) and diaphragm (descends and increases depth of thoracic cavity)
- Expiration: no muslces, just the recoil back
What muscles are for FORCED inspiration and expiration?
- Inspiration (SIPS): SCM (elevates sternum), Scalenes (fix or elevate ribs 1-2), pectoralis minor (elevates ribs 3-5), Internal internals, intercartiagionous part (aid in elevating ribs)
- Expiration: Intercostals, interosseous part (depress ribs 1-11 narrow thoracic cavity), Rectus abdominis (depresses lower ribs, pushes diaphragm upward by compressing abdominal organs), external abdominal oblique (same effects as rectus abdominis)
How do to the ribs move in expiration and inspiration?
What are the sequence of events for inspiration?
You need to increase volume to decrease pressure (think about molecules in a small and large container)
What are the sequence of events for expiration?
Increase pressure by decreasing volume
What are the three most important gases in the air? What are their percentages in air?
Nitrogen, O2, CO2
What is the pO2 and pN2?
- pO2: 760mmHg * 21%= 160mmHg
- pN2: 760mmHg * 79% =600mmHg
What are the partial pressures of Po2 and Pco2 when entering alveolar capillaries, alveoli, and leaving alveolar capillaries?
What is the way you can change the air pressures?
Altitudes:
* Higher heights: has less pressure so less Po2
* Lower: more pressure so more Po2
What is the approximate percentage for inhaled and exhaled (N2, CO2, O2, H2O) ?
Nitrogen stays the same because it comes from digestion and not from vent.
O2 decreases in exhalation
CO2: increase in exhalation
Fill in
What prevents the lung and airways to not collapse?
Negative intrapleual pressure
Pressures:
* Atmospheric:
* Intrapleual pressure:
* Intra-alveolar pressure:
* Transpulmonary pressure:
- Atmospheric: 760 mmHg (or 0mmHg)
- Intrapleual pressure: 756 mmHg (or -4 mmHg)
- Intra-alveolar pressure: 760 mmHg (or 0 mmHg)
- Transpulmonary pressure: Palv-Pip = 4 mmHg
What causes the pelural sac negative pressure?
Lungs want to recoil in and chest wall wants to recoil out therefore causing the negative intrapleural pressure (ALLOWS the chest wall and lungs to move together)
If we do not have this, then the lungs will win and cause the lungs to collapse.
What is a pneumothorax? What events lead to this?
Pneumothorax: presence of air in pleual cavity
* Thoracic wall is punctured
* Inspiration sucks air through the wound into the pleural cavity
* Potential space becomes an air-filled cavity
* Loss of negative intrapleural pressure allows lungs to recol and collapse
Atelectasis
Explain the changes in alveolar pressure move air in and out of the lungs
What is the time difference betweeen inspiratory time and expiratory time? What does this difference cause?
- The inspiratory time (TI) is 2 seconds and is less than the expiratory time (TE) of 3 seconds.
- This difference is a result of, in part, a higher airflow resistance during expiration, as is reflected by a higher alveolar pressure (PA) change during expiration (1.2 cm H2O) than during inspiration (0.8 cm H2O
An increase in airway resistance will cause what?
decrease the inspiratory time/expiratory time ratio