Chapter 9: Gas Exchange and Smoking Flashcards
features of human gas exchange system
- link circulatory system with atmosphere
- cleans and warms air thats breathed in
- maximises surface area for diffusion of O2 & CO2 between blood and atmosphere (alveoli increase it)
- minimise distance for diffusion
- maintain adequate gradients for this diffusion
process of gas exchange in unicellular organisms:
simple diffusion of o2 from environment through cell membrane to cytoplasm
collective surface area of alveoli in lumps ie _ is _
ie total gas exchange surface =70m2
capacity if thoracic cavity
5dm3 or 5l
air passage
nose, trachea, bronchus, terminal bronchiole, respiratory bronchiole, alveolus
function of C shaped cartilage in trachea
- keep it open
- maintain air resistance ie low
- prevent collapsing/bursting as air pressure goes high/low respectively
bronchus has what instead of C shaped cartilages to serve the same function
irregular blocks of cartilage
what encloses gas exchnage system
throacic cavity
pleural membrane …
covers lung, fluid between pleural membrane space allows friction free movement as lungs are ventilated
bronchiole walls have and dont have :
smooth muscles that contract/relax to adjust diameter of airways. dont have cartilage
which 2 are sites of gas exchnage
alveolar duct and alveoli
which have cilia
trac,bron, tbron and rbron few
which have smooth muscle
trac,bron, tbron
which have cilia and goblet cells
trachea and bronchi
approx no and diameter of trachea
1, 1.8cm
approx no and diameter of bronchus
2, 1.2cm
approx no and diameter of t bronchiole
48000, 1mm
approx no and diameter of r bronchiole
300,000, 0.5mm
approx no and diameter of alveolar duct
9*10
significance of cartilage in trachea and bronchus
keeps airways open and air resistance low and prevents from collapsing as air pressure changes during breathing
significance of thoracic cavity
its closed cavity bordered by diaphragm at base and ribs having intercostal muscles in between at sides. helps in supporting and maintenance of pressure inside throracic cavity to support inspiration/expiration
why are bronchioles made up of smooth muscles and not cartilage
these can contract and relax to adjust diameter of tiny airways. during excercise muscles relax to allow greater flow of air to alveoli, absense of cartilage makes these adjustments possible