respiration Flashcards
explain the arrangement of function of the zones of the respiratory system
conducting zone = first 16 generations (gen 0 is the trachea as air enters here first), includes the nose, nasopharynx, oropharynx, pharynx, larynx, trachea, bronchial tree
responsible for filtering, warming and humidifying the air
respiratory zone - where gas exchange occurs, gen 17 and onwards, alveoli are present
what is the importance of 1) warming and 2) humidifying the air as it enters the lungs
1) gases are more soluble when cold, if the air is cold upon entering the blood and warms up there, decreasing it’s solubility, bubbles may form
2) addition of water vapour helps not to dry out the airways
describe the structure of the bronchi walls
Cartlidge rings
smooth muscle to control airway diameter
epithelial cells (ciliated) to remove particles out of the lings
goblet cells in the epithelia to produce mucus (at a closely moderated amount)
elastic tissue
respiratory peithelium - what properties do they have?
they are ciliated and are interspersed with goblet cells
there are nerve endings that sense noxious substances
how do bronchioles differ from bronchi?
they have no cartilage (but still have the epithelial lining)
they have proportionally more smooth muscle
explain the specialisations of alveoli and their cell types
thin walled, very close to surrounding capillaries - short diffusion pathway etc…
gas exchange takes place across epithelium type 1/ type 1 pneumocytes which have a flattened cytoplasm, everything is squished close together to speed up diffusion
type 2 epithelia produce surfactant
they increase SA - 50-100m^2
explain how quiet inspiration works and whose law this follows
Atmos. Pressure is greater than alveolar pressure
Diaphragm contracts and flattens,
External intercostal muscles contract lifting rib cage up and out,
Thoracic cavity and lungs inc. in volume, pressure decreases below atmospheric pressure
Boyle’s law
explain how forced inspiration works
same as quiet but with some added help -
scalene (neck muscles) and back muscles assist in pulling rib cage up
upper respiratory tract reduces resistance to flow
explain how quiet expiration works
passive process
no contraction of muscle contributes, instead elastic recoil is used
the muscles form quiet inspiration (diaphragm, external intercostal), ribcage lowers back, diaphragm domes up thoracic cavity and lung volume decrease, pressure inside exceeds atmospheric, air is forced out
what additional things happen in forced expiration?
abdominal muscles contract to push diaphragm up
neck and back muscles do something
internal intercostal muscle pulls ribcage in
explain the structure and function of the pleura
there’s one pleural membrane on the outside of the lungs, an interpleural space filled with fluid (allows for movement between lungs and chest as one) and then a membrane on the chest wall
at resting the lungs would collapse inwards due to their elastic nature, while the chest wall would tend to expand
these forces act in opposition on the pleural membranes and find a balance
this creates a sub atmospheric (below atmospheric) pressure between the two membranes
explain what happens in a pneumothorax
a collapsed lung
interpleural space is pierced, you lose the outer force of the chest, the inward force of the lungs due to the elastic nature wins, and the lung collapses
define compliance (lungs) and what it means to have high/low compliance
the ease with which the lung and thorax expands during a pressure change
low compliance = more effort required to breathe in and get the necessary volume change
high compliance = expiration is difficult, lack of elastic recoil (emphysema)
explain what surface tension is
attractive forces occur between water molecules
this means, at the surface, there are sideways and downwards forces toward other water molecules, but no upwards force, resulting in tightly packed water molecules at the surface with a tendency to dive down into the bulk of the solution
explain the forces in a bubble and the equation involved (Lapalace’s equation)
do small or larger bubbles have the greater pressure?
the pressure of the gas inside the bubble balances with the surface tension of the surrounding water
P = 2T / r
so the smaller the bubble (smaller radius), the higher the pressure
smaller bubbles have a greater pressure than larger ones
pressure moves from high to low
what problem does this present in the lungs?
how is this problem solved?
alveoli are like bubbles, and so gas would move from small alveoli at high pressure to larger ones and the small ones would just deflate which is pointless
surfactant produced by type 2 pneumocytes
it’s made of lipids mostly, plus some proteins, and acts like a detergent to reduce surface tension
hydrophilic head in the water with the hydrophobic tail sticking out provides an upward force to reduce surface tension, making it easier for expansion
surfactant ensures all alveoli inflate, but what else does it do?
prevents overexpansion - the surfactant’s density decreases as the alveoli stretches, reducing it’s effects so surface tension increases, assisting alveoli in recoiling/not overexpanding
define anatomical and physiological dead space
anatomical = volume of conducting airways
physiological = volume of lungs not participating in gas exchange, so conducting airways + non functioning
there are 8 things to know from a spirometer - what are they?
IRV = inspiratory reserve volume (from peak of normal breath to peak of max breath)
FEV = forced expiratory volume (fill lungs AMAP, blow out as hard as possible in 1 sec)
VC = vital capacity - deep breath in then breath out as much as you can
RV = residual volume, volume of air left in lungs you cannot breath out
TLC = total lung capacity RV + VC
TV = tidal volume = volume breathe in after 1 sec
ERV = expiratory reserve volume, how much you can force out after a normal exhale
FRC = functional residual capacity RV + ERV
in exercise tidal volume increases, but our lung’s capacity doesn’t change - how so?
residual volume decreases so the sum of TV and RV remains the same
