past paper questions Flashcards
features of normal expiration
- passive
- diaphragm muscles relax
- diaphragm moves up / becomes dome shaped
- external intercostal muscles relax
- ribs move down and in
- elastic fibres recoil
- volume of thorax reduced
pressure in thorax increased - pressure in thorax greater than atmospheric pressure so air moves out of lungs
features of forced expiration
- active
- requires energy
- internal intercostal muscles
contract - ribs pulled down hard
- abdominal muscles contract
forcing diaphragm up
how are features in a bony fish (for gas exchange) adapted to maximise gas exchange
-gill, filaments / lamellae
large surface area
-thin for short diffusion distance
-good blood supply for maintaining steep concentration gradient
-counter current system
how do gills slow down water movement
the tips of gill filaments overlap
how are features in a bony fish (for ventilation) adapted to maximise ventilation
-water enters mouth due to pressure change in buccal cavity
-water flows over gills and leaves via operculum
-one direction of flow
whats ventilation
-ventilation is muscular movements that result in delivery of fresh supply of air or water to an exchange surface
what is gas exchange
-gas exchange is the diffusion of oxygen and carbon dioxide at an exchange surface
role of cartilage in gas exchange
stops, trachea / bronchus, from collapsing
role of elastic fibres in gas exhange
recoil of alveolar
how is the nasal cavity adapted for efficient gas exchange
-large surface area and good blood supply
-mucus secreting cells trap dust and microbes
-moist surfaces, increase humidity and reduce evaporation from surfaces in lung
how is the trachea adapted for efficient gas exchange
-cartilage rings to stop it collapsing
-ciliated epithelium and goblet cells secret mucus, trap dust and microbes and move them towards stomach
how are the alveolar adapted for efficient gas exchange
-thin (epithelial) wall, reduces diffusion distance
-collagen / elastic fibres, elastic recoil to help squeeze air out
during exhalation
-large number / provide large surface area, to increase rate of diffusion
why can exhalation be a passive process
-it does not use muscle contraction / muscles (just) relax
-lungs (elastic so) will recoil
what is the effect of the contraction of smooth muscle in the walls of the airways on ventilation (allergic reaction)
-reduction in (lumen) diameter of, bronchi /
bronchioles
-harder to exhale as less air can be exhaled
-more air remains in the lungs
-harder to inhale due to greater resistance to inhalation
-harder to ventilate
how are gills adapted for gas exchange
-many lamellae provide large surface area
-secondary lamellae on main lamellae provide large surface area
-short distance between blood and, water/ outside so blood maintains diffusion gradient
difference between tissue and organ
-tissue has few types of cell and performs few functions
-organs consist of several tissues
how would u carry out a dissection to display maximum detail of bony fish gas exchange system
-removal of operculum
-observe structures under
water
