respiratory system Flashcards
Nasal cavity
- add moisture to air in order for it to not irritate our airways (mucus, hair etc).
- Also mouth region
pharynx
Common area of respiratory tract
* Respiratory and digestive diverge
* Flap - opens/close when breathing or swallowing
Trachea
- bands of cartilage to functionally keep it open and solid so it doesn’t collapse whenever we breathe
- Air can move unrestricted
Bronchus
supply air to each lung
* primary > secondary > bronchiole
Diaphragm
At rest: semicircle
Contraction: pulls down and becomes flat
right lung
3 lobes
left lung
2 lobes, cardiac notch (where heart sits and rests)
Bronchiole
- Don’t contain any cartilage
- Kind of like arteries - Made up of smooth muscles
- Control mechanism to allow air flow into underlying structure called alveoli
- Endothelial layer and smooth layer
- Controlled to alter diameter - alter air flow
Alveoli
- Terminal sacks - terminate at the end of respiratory system
- Where gas exchange occurs - functional unit
Capillary beds
- Sit on top and are in very close association
- Single cell layer of capillaries allows rapid exchange between alveoli (gases) and the blood
Partial pressure
each individual gas in mixture (air) will have this
Knowing partial pressure allows us to…
predict gas movement
Gases always diffuse from a region of…
high partial pressure to a low partial pressure
O2 & CO2 partial pressure
760 mm Hg (atmospheric pressure) of all gases in atmosphere (surrounding us)
* 21% oxygen in atmosphere
- O2: 760 x 0.21 = 160 mm Hg
* 0.03% carbon dioxide in atmosphere
- CO2: 760 x 0.0003 = 0.23 mm Hg
negative pressure breathing
To move O2 from atmosphere into our lungs, the pressure must be lower in the lungs
* Pulling in rather than pushing air into our lungs
* Achieved by expansion of the chest wall by muscle contraction
* Creating a gradient
Why do our lungs expand when our chest contracts?
A double membrane surround the lungs
- One side adheres to the outside of the lung, the other to the wall of the thoracic cavity (ribs)
- Filled with fluid that creates surface tension
Visceral pleura
on organ side (surface of lung)
Parietal pleura
- Stick to the rib cage bc of surface tension and the water molecules associated with the fluid inside this space that creates hydrogen bonds (strong)
- Fluid in this space - the water molecules are attracted to each other
- When ribs/diaphragm expands it pulls the lungs with it because of these bonds
- Active process
Breathing out - expiration
- Usually does not require the contraction of any muscles
- Passive process
- Relaxation of diaphragm and rib cage reduces the volume of the thoracic cavity driving air out of the lungs
Increasing pressure - drive air out
Lung capacity @ inflation/deflation
Total lung cap. at max inflat. - 5700mL
Var. in lung vol. -
* end of normal inspiration - 2700mL
* end of normal expiraation - 2200mL
Min lung vol. at max. deflat. - 1200mL
Spirometry
simple, noninvasive test that measures the volume and flow of air inhaled and exhaled by the lungs
* Forced vital capacity (FVC): This is the total volume of air exhaled during the entire spirometry test.
* Forced expiratory volume in one second (FEV1): This is the volume of air exhaled during the first second of the test.
* Peak expiratory flow (PEF): This is the maximum speed of exhalation during the test.
* Forced expiratory flow (FEF): This is the average flow of air during the middle portion of the exhalation.
What prevents the collapse of alveoli?
Surfactant - lines inner lining of alveoli
Hydrogen molecules attract to each other which would cause alveoli to collapse but surfactant is secreted and prevents this - minimises reaction
Oxygen is predominantly transported around the body bound to…
haemoglobin within red blood cells
* 98% transported this way
* 2% dissolved in plasma
CO2 transported by 3 different mechanisms:
- 7% dissolved in plasma
- Remaining 93% within RBCs but via 2 separate mechanisms
23% bound to haemoglobin
70% converted to bicarbonate
Each haemoglobin molecules can carry
4 molecules of O2
Oxyhaemoglobin saturation curves
At normal P O2 levels, haemoglobin is 98% saturated
Minor changes in P O2 do not have a significant effect on saturation
Haemoglobin is a large store for O2 within the body
hypoxia
low O2 levels within the blood
* If diffusion of gases between alveoli and blood is impaired or oxygen transport in the blood is altered - hypoxia
hypoxic hypoxia
low arterial PO2
Anemic hypoxia
decreased total amount of O2 bound to hemoglobin
Ischemic hypoxia
reduced blood flow
Histetoxic hypoxia
failure of cells to use O2 because cells have been poisoned
Obstructive lung disease
Asthma
Emphysemas
Restrictive lung disease
Impacting expansion of lungs
Asbestosis
Pneumothorax
Collapsed lung
* Break bonds connecting lungs to rib cage - changing pressures in pleural membranes will break bonds
* Air, blood, fluid fills this space and therefore lungs cannot inflate
Involuntary responses
receptor driven
* sneezing
* coughing
* hiccups
Tidal volume at rest
500 mL
