Respiratory System Flashcards
(39 cards)
What is external respiration?
Exchange of O2 & CO2 between an organism and the external environment.
State functions of the respiratory system.
Gas exchange, olfaction, speech, homeostasis, protection.
What is cellular respiration?
Utilisation of O2 by cells in metabolism.
Describe saline secretion by airway cells.
NKCC brings Cl- into epithelial cell from ECF.
Apical ion channels secrete Cl- into lumen.
Na+ moves into lumen via paracellular pathway, down EC gradient.
NaCl & water movement into lumen down conc gradient from ECF.
Describe the function & features of NOSE.
Filters & warms air.
- Epithelia secrete mucus
Smell.
Describe function & features of NASOPHARYNX
Warms air.
ADENOIDS fight infections - secondary lymphoid tissue.
Eustachian tubes equalise ear pressure.
Describe function & features of PHARYNX
Air & food passage.
TONSILS - secondary lymphoid tissue. Air flow resistance during infection.
Describe function & features of LARYNX.
Vocal chords.
GLOTTIS.
Describe function & features of TRACHEA.
2O C shaped cartilage rings & smooth muscle (C shaped)
Patency of airway.
Describe function & features of BRONCHI
Similar to trachea.
Ciliated epithelial cells - secrete mucus & saline.
____ receptors mediate broncho-constriction, ____ receptors mediate broncho-dilation
M3 muscarinic cholinergic receptors
β2 adreno-receptors
Alveoli: describe function of type 1 & 2 epithelial cells
1 - gas exchange
2 - synthesise surfactant -> reduces surface tension & resistance during breathing.
Describe the structural features of an alveoli.
Rich blood supply (capillary network)
Large surface area - spherical
V thin epithelia - 1 cell thick - rapid gas diffusion.
Describe the pathway of pulmonary gas transport.
- O2 enters blood via alveolar-capillary interface.
- O2 transported in blood dissolved in plasma or bound to Hb in RBCs
- O2 diffuses into cells.
- CO2 diffuses out.
- CO2 transported dissolved, bound to Hb or HCO3-.
- CO2 enters alveoli at alevolar-capillary interface.
State the equation for O2 & Hb association in RBCs
O2 + Hb –> HbO
What colour is arterial blood & why?
Red
HbO complex fully saturated with O2
What colour is venous blood & why?
Purple
HbO complex devoid of O2.
Describe the structure of a Hb molecule.
4 polypeptide chains:
2α & 2β.
Each chain has a haem group cont. Fe2+ which can bind an O2
How many O2 molecules can 1 Hb molecule bind?
4
Sketch a dissociation curve
Sigmoidal.
What factors increase P50 (DECREASE AFFINITY)
> > Temp.
PCO2
2,3 DPG
«_space;pH
What factors decrease P50 (INCREASE AFFINITY)
«_space;Temp.
«_space;PCO2
«_space;2,3 DPG
» pH.
Describe the trend of a dissociation curve.
Sigmoidal:
PO2 0-60: abundant O2 but small change of O2 - stimulates 02 release in tissue
Inflection point: INCREASED AFFINITY for O2 molecules as conformation alters.
Plateau: O2 saturation.
What is cooperative binding?
When Hb binds to an O2 molecule, the conformation alters to favour O2 binding (»> affinity).
