Respiration 1 Flashcards
1
Q
What is the function of respiration?
A
- primary function is gas exchange
- In mammals occurs in lungs
- Inspiration: air rich in O2 inhaled in lungs
- expiration: CO2 produced during oxidative processes of the body is exhaled from the lungs
- Both gases are transported by the blood, so both the CVS and the respiratory system are involved with supplying body cells with O2 and eliminating their waste product, CO2
2
Q
What is the passage of air in the respiratory tract?
A
- 1st place through the nasal septum and the nasal turbinates (filter the air and clean it of big dust particles)
- From the nose, warmed and moistened air goes through the pharynx (also food) then through the larynx (vocal cords)
- the lungs and the airways share the chest cavity with the heart, the great vessels and the esophagus
- Then through the trachea (cartilage rings) into the right bronchus and left bronchus that both branch into lobar and segmental bronchi, right has 3 lobar bronchi since three lobes and left has 2 lobar bronchi since only two lobes and continue to branch until terminal bronchioles (no alveoli) and finally alveoli that are surrounded by capillaries for gas exchange
3
Q
What is the blood flow like in the lung capillaries?
A
Deoxy blood from the right heart comes in and get oxygenated at the capillaries surrounding the alveoli and then oxy blood goes back to the left heart to be redistributed to the systemic circulation
4
Q
What does a cast of the respiratory tract teach us?
A
- to appreciate the extent of airways
- Huge surface area for gas exchange
5
Q
How can lungs inflate?
A
- Cannot do it on their own need muscles (diaphragm that contracts down and increases the longitudinal dimension of the rib cage but also the intercostal muscles that increase the cross-sectional area of the rib cage), when they contract the rib cage size increases
- Lungs are still not inflated, need to couple rib cage to lungs via the pleural space (if muscles contract pull the rib cage but bcs of coupling via tiny amount of fluid => pulls lungs open)
6
Q
What are the pleura?
A
- Thin cellular sheet attached to the thoracic cage interior (parietal) and folding back upon itself, attached to the lung surface (visceral pleura) forming two enclosed pleural sacs (one around each lung) in the thoracic cage
- Parietal and visceral are continuous with each other attached to the lungs and rib cage but there is one sac for right and one sac for left (these two not interconnected)
7
Q
Why do we say that lungs are like balloons?
A
When muscles contract, lungs expand so the volume increases and air molecules have more space to move around, so pressure decreases and air can flow from the outside to the inside of lungs down the pressure gradient
8
Q
What is the significance of pleural surfaces?
A
- Coupling contraction to lung expansion since they are so tightly connected, difficult to pull apart due to suction, there is a negative pressure in between them because all there is is a tiny bit of water
- A way to visualize the apposition of the two pleural surfaces is to put a drop of water between two glass microscope slides. The two slides can easily slide over each other but are very difficult to pull apart
9
Q
What happens to the pleural space when there is pneumothorax?
A
- We say the reference pressure outside is 0 though it is not actually 0 and when nose and mouth are open but there is no inhale nor exhale, the pressure is also “0” in the lung, however the pressure in the pleural space is - 5 cm H20 compared to the reference pressure, why? it is not fully understood but lungs want to collapse and rib cage wants to expand at rest, water is in between these opposing forces and so the pressure in the water is negative because think of the microscope slides, if pull apart, negative pressure
- If pneumothorax, so puncture the pleura, air from the outside comes into the pleural space, the pressure equilibrates with outside and coupling is removed with pleural space, lungs collapse and rib cage expands, both are
