respiratory system Flashcards
how does an asthmatic airway look?
walls inflamed and thickened.
surfactant in airways.
The effects of surface tension; the fluid lining the alveoli naturally exerts surface tension which
causes the lungs to want to collapse and resist expansion.
- Surfactant: secreted via the alveoli cells to reduce the surface tension.
Patm stands for
Pressure of the atmosphere (outside pressure)
Palv stands for?
Pressure within the alveoli (inside pressure)
PIp
Intrapleural Pressure or pressure within the pleural cavity. Also
known as negative pressure
what are the four divisions in the lung of VOLUMES?
tidal volume. inspiratory reserve volume. expiratory reserve volume. and residual volume.
what are the four lung capacity groups?
vital capacity, total lung capacity, inspiratory capacity and functional residual capacity.
what is minute ventilation?
Minute Ventilation (VE) = tidal volume (VT) x breathing frequency (f). healthy person at rest will take 12 breaths per minute.
what is known as dead space or Vd.
Some of the inhaled air never gets to the alveoli so cannot gas exchange = 150ml
Alveolar ventilation
is the amount of air that gets into the alveoli. Alveolar ventilation is tightly regulated to ensure that there is always the right amount of fresh air available in the alveoli for gas exchange.
what is increased alveolar ventilation known as?
Hyperventilation – Fast Deep Breathing
what is decreased alveolar ventilation known as?
Hypoventilation – Slow Shallow Breathing
what does atmospheric air consist of?
- Nitrogen (N 2) = around 78%
- Oxygen (O 2) = around 21%
- Small amounts of carbon dioxide (CO 2) = around 0.04%
what is the gradient between alveolar and atmospheric o2?
PAO2 is lower (100mmHg) than atmospheric O2 (160mmHg) because some of the O2 that enters the alveoli leaves by entering the pulmonary capillaries.
what is the difference between alveolar CO2 and atmospheric air?
(PACO2) is much higher (40 mmHg) than that in atmospheric air (close to zero)
what is the rate at which diffusion occurs?
D(gas) x surface area x ^P(gas) / thickness.
note ^P(gas) = P1 - P2
what diffuses quicker CO2 or O2?
CO2 diffuses about 20x faster than O2 due to CO2 higher solubility.
gas exchange of O2
O2 = alveoli (100mmHg) -> blood (95mmHg)
gas exchange of CO2
CO2 = blood (45mmHg) -> alveoli (40mmHg)
how is O2 transported through the blood (two forms)
- Combined with haemoglobin.
- Dissolved in plasma
how is co2 transported through the blood (three ways)
- Dissolved in plasma. (7%)
- Combined with haemoglobin
- As bicarbonate -HCO3-
how many O2 molecules can 1 Hb carry?
4
how is the majority of O2 carried.
bound to Hb
O2 binds to haem group with contain iron ions.
yes
how much Hb does healthy blood contain?
approximately 150mg per litre and each gram of Hb can carry 1.34ml of O2.
what is the Hb-O2 saturation percentage of arterial blood?
98%
what is the Bohr effect
describes haemoglobins affinity for oxygen.
what is the Hb-O2 saturation percentage of venous blood?
75%
what does left shift on the oxy-haemoglobin dissociation curve mean? and how is it caused?
occurs in the lungs and facilitates more loading of oxygen (increased loading). caused by lower levels of CO2/H+ and low temp.
what does right shift on the oxy-haemoglobin dissociation curve mean? and how is it caused?
occurs in the tissues and facilitates more release of oxygen (increased unloading). cuased by higher levels of CO2/H+ and high temp.
what percent of carbon dioxide is dissolved in plasma ?
7% percent is transported out of the tissues as it is dissolved in plasma.
what percent of carbon dioxide is bound to haemoglobin?
Approximately 23% of CO2 is transported out of the tissues in blood, bound reversibly to the protein subunits of haemoglobin (globin chains).
- CO2 bound to Hb, and in this form, Hb has a much lower affinity for O2.
What per cent of carbon dioxide is transported as bicarbonate ions?
70%. Most of CO2 is produced by the tissue us carried within the blood as HCO3-.
Conversion from CO2 -> HCO3 happens in red blood cells with the assistance of an enzyme.
HCO3- produced can then move out into the plasma.
what is Alkalosis?
increased pH (above normal pH>7.45). due to decreased concentration of H+ ions. can compensate by hypoventilation to increase CO2(breath hold) thus increasing H+ ion concentration in the blood.
what is acidosis?
Decreased pH, below normal range (pH < 7.35).
- Due to increased concentration of H+ ions.
- Can be compensated for by Hyperventilating to decrease CO2 (breath more off); thus decrease H+ ion concentration in the blood.