exchange surfaces and breathing SLOP Flashcards
three main factors affecting the need for an exchange system
size
surface area
level of activity
describe and explain three features of a good exchange surface
large sa - provide more space for relevant molecules to pass through
thin permeable barriers - decreases diffusion distance
good blood supply - keeps high conc grad for rapid diffusion
describe how human alveoli are adapted to reduce diffusion distance
2 cells thick
contain squamous cells
capillaries are close in contact with alveoli walls
capillaries are narrow to restrict RBC movement
describe the role of surfactant
coats the internal surface of the alveoli to reduce cohesive forces between water molecules preventing collapse
what tissue type comprises alveolar walls
squamous epithelium
describe how the nasal cavity is adapted for exchange
large SA with good blood supply
warming air to body temp
lined with hair to trap dust + pathogens
protect from infection (hairs)
moist surfaces to increase the humidity of incoming air, reducing evaporation from exchange surfaces
describe what is meant by tidal volume stating a typical figure
volume of air moved in and out with each breath at rest e.g. 0.5dm3
most bony fish have 5 pairs of gills which are covered by a bony flap, known as the…? what is the function of this bony flap?
operculum ; protects the gills and ensures a constant flow of water
describe the structure of gills in a body fish
two rows of gills filaments; these are slender branches of tissue known as the primary lamellae and are attached to a bony arch. Each gill filament is folded into secondary lamellae providing a large surface area
describe ventilation in bony fish
buccal cavity (mouth) can change volume; floor of mouth moves downwards, drawing water into the buccal cavity; mouth closes and water is pushes through the gills. As water is pushed from the buccal cavity to gills, the operculum moves outwards.
what is function of tracheal fluid
gaseous exchange occurs between air in tracheal and the tracheal fluid
when an insect is active, what changes occur in the insect to increase their oxygen supply
tracheal fluid can be withdrawn into the body fluid to increase the surface area of the tracheal wall exposed to air.
how does air enter the tracheal system in an insect
spiracles (pores)
the trachea and bronchi are lined with cartilage. Describe why.
C shape rings of cartilage line these tubes, preventing collapse during inspiration. The C shape allows food to pass down the oesophagus behind the trachea.
***explain why smaller organisms have a lower demand for oxygen than larger organisms
smaller organisms have a larger SA:V ratio than larger organisms; simple diffusion can be sufficient for unicellular organisms but due to many-layered multicellular organisms, it would be too slow. Multicellular organisms therefore need transport systems.
describe the mechanism for inspiration
-diaphragm contracts (flat)
-external intercostal muscle contract
-rib cage up and out
-vol of thorax increases
-pressure decrease below astmospheric pressure
-air into lungs down conc grad
why do alveolar walls contain elastic fibres
to stretch during inspiration and recoil, pushing air out ,during inspiration
describe the function of goblet and ciliated epithelial tissues that line the trachea
goblet cells produce mucus onto the tracheal lining, trapping dust and microorganisms. The cilia then beat and move the mucus away from the lungs and towards the throat.
why is the trachea and bronchi lined with cartilage?
C shape rings of cartilage line these tubes, preventing collapse during inspiration. The C shape allows food to pass down the oesophagus behind the trachea
role of smooth muscle and elastic fibres
smooth muscle can involuntarily constrict airways
elastic fibres elongate smooth muscle again, recoiling airway to its original shape and size (dilates airway)
describe precautions that must be taken when using spirometer
subject should be free of asthma, there should be no air leaks in the apparatus; mouth piece must be sterilised; soda lime should be fresh and functioning.
describe what is meant by vital capacity and state the factors that depend on it
the max vol of air that can be moved by the lungs in one breath; measured by taking one deep breath and expiring all the possible air from the lungs. Depends on size of person, age/gender and exercise levels
usual range for vital capacity
2.5 - 5.0 dm3
what is residual vol and state the standard volume
vol of air that remains in the lungs even after forced expiration (ie air in the alveoli and airways) = 1.5dm3
state the equation for ventilation rate
ventilation rate = tidal volume x breath rate (bpm)
how is air supplied to the respiring tissues in an insect?
tracheal system
