Respiratory Introduction Flashcards
Functions of the respiratory system (4)
Gas exchange:
- oxygen added to blood from air
- carbon dioxide removed from blood into air
Acid base balance
Protection from infection:
- dense cilia network within epithelia to remove trapped larger particles in the mucus
Communication via speech:
- air moving through vocal chords in larynx
Points of gas exchange between respiratory and cardiovascular systems
Exchanged at level of lungs and periphery tissue
CVS system transports oxygen from lungs to tissue to be metabolised - then transports waste products (CO2) to be expired
In relaxed state, what is the net volume of gas exchanged in the lungs (O2 & CO2)
250ml/min O2
200ml/min CO2
This is equal to the net volume exchanged in tissues
Why is it important that net volume exchanged in lungs = volume exchanged in tissues
Prevents gas build up in circulation
Ensures supply = demand
How does respiratory rate and heart rate change during exercise?
Respiratory rate:
- increase rate and depth of breathing —> greater O2 acquisition, waste disposal (CO2)
Heart rate:
- increase in heart rate and force of contraction —> speeds up oxygen delivery to muscles & waste removal
What is normal respiration rate? What is max capacity in adults?
Normal: 12-18 breaths/min
Max: 40-45 breaths/min
What is systemic circulation vs pulmonary circulation
Systemic: goes to all areas of body delivering O2 from peripheral tissues and collecting CO2.
Pulmonary: only travels between heart and lungs
In terms of oxygenated and deoxygenated blood, what to the pulmonary/systemic arteries/veins carry
o Pulmonary artery carries deoxygenated blood
o Pulmonary vein carry oxygenated blood
o Systemic arteries carries oxygenated blood
o Systemic veins carries deoxygenated blood
(Artery = away from heart) (Vein = towards heart)
What is the path of air entering from the nose to the lungs
Nose (better at moistening air than mouth (air needs to be in solution to diffuse into blood))
Pharynx (links nose and mouth - splits at larynx to join respiratory system or oesophagus)
Epiglottis (flap that sits on top of larynx - gate to respiratory system, closed when we swallow)
Larynx (vocal chords are here)
Trachea (largest airway - travels down from larynx to sternal angle - splits into two primary bronchi)
Bronchus (divides 24 more times getting smaller and smaller - end in blind ending sacs called alveoli)
Lung (alveoli where gas exchange occur)
What lobes are the lungs split into
3 lobes in right
- superior
- middle
- inferior
2 in left
- superior
- inferior
What fissures are in R and L lungs
R:
- horizontal (higher)
- oblique (lower)
L:
- oblique
What is the pleural cavity?
Space between lung and wall of thoracic cavity
Where is the boundary for the upper and lower respiratory tract?
Boundary between the larynx and the trachea
Trachea and below = lower respiratory tract
How do the primary bronchi branch?
Branch into secondary bronchi - one secondary bronchi goes into each lobe of lung
Why do the trachea and bronchi contain cartilaginous C-shaped rings? When are they lost?
Maintains patency of the airways (keeps them open to allow are to move freely along it)
Lose C-shaped ring below level of bronchi - airways now called bronchioles
Why does gas exchange only take place in alveoli?
Only place where the walls are thin enough
What is the dead space?
Any air that is in the rest of the lungs not the alveoli e.g. air that is in the conducting zone (walls too thick for gas exchange)
How do the R and L primary branch of bronchi differ? Why’s this important?
R primary branch is wider and more vertical
Important as foreign bodies more likely to get stuck in left bronchi (due to acute angle)
Why are the alveoli covered in elastic fibres?
Allow for inflation of the alveoli during inspiration
Energy stored in the fibres as they inflate is released during expiration which squeezes the alveoli to release air (important as expiration at rest is passive)
What are type 1 alveolar cells?
Make up the bulk of the alveolar wall - gas exchange takes place across type 1 alveolar cells
What are type 2 alveolar cells?
Not involved with gas exchange
Type 2 cells secrete surfactant which makes inspiration easier
Type 1 cells are intermittently studded with type 2 cells
Which type of alveolar cells are capillaries found next to?
Always type 1 as these ones are involved in gas exchange (minimises distance gas has to travel when diffusing)
What is the total lung capacity?
6 litres
2 x 3L lungs
Why does air flow vary across respiratory tree?
As you move down respiratory tree diameter of airways gets smaller
More resistance occurs in LARGEST airways (due to diameter of airways vs. How many airways)
Cross sectional area of trachea is only 2.5cm^2 while cross sectional area of bronchioles is 5000cm^2 (greater are for air flow in smaller airways)
