Chapters 7 & 8 - Exchange and Transport in Animals Flashcards
why can small organisms gains all O2 and CO2 needed be gained by diffusion
- low metabolic activity means low oxygen demands
- They have a short diffusion distance and high surface area to volume ratio
why can large organisms not depend on diffusion to supply all gases
- high metabolic demands
- low SA:V ratio and diffusion distance is too large
Surface area: volume ratio calculation, how to display?
SA/V
model as: x:1
pattern of decreasing SA:V ratio
size of organism and diffusion distance increases
how does increased surface area help gas exchange
provides area needed for exchange and overcomes the limitations of low SA:V in large organisms
how do short diffusion distances help gas exchange
process of diffusion is faster and more efficient
how does a good blood supply help gas exchange
- substances constantly delivered and removed from the exchange surface
- maintains a steep concentration gradient
how does ventilation help gas exchange
maintains conc grad for gases
mammalian gas exchange system: nasal cavity
- high SA and good blood supply (warms air to body temp)
- hairy lining and goblet cells trap bacteria and dust to prevent irritation
- moist surfaces: increase humidity of air to reduce evaporation from the exchange surface
mammalian gas exchange system: trachea
- supported by C-shaped cartilage rings to prevent collapse
- lined with Ciliated epithelium and goblet cells that trap and remove dust to be swallowed and digested
mammalian gas exchange system: bronchi
- branch off trachea to each lung
- 2
- similar structure to trachea
mammalian gas exchange system: bronchioles
- branch from bronchi
- no cartilage rings
- smooth muscle walls
- muscle contracts/ dilate to change airflow
mammalian gas exchange system: alveoli
- 1 cell thick wall
- collagen and elastic fibers allow stretch and recoil
- good blood supply and ventilation
- lung surfactant prevents alveolar collapse
inspiration
- diaphragm contracts, flattens and lowers
- external intercostal muscles contract
- ribs move up and out
- thorax volume increases, pressure decreases
- air drawn in
expiration
- diaphragm relaxes
- external intercostal muscles relax
- ribs move down and in
- thorax volume decreases, pressure increases
- air forced out
forced expiration
- internal intercostal muscles contract to force ribs down quickly
vital capacity
volume of air the lungs can breathe in with the strongest exhalation and deepest possible breath intake
tidal volume
the volume of air that moves in and out of the lungs with each resting breath
breathing rate
the number of breaths taken per minute
ventilation rate formula
tidal volume x breathing rate
insects: spiracles
openings along the exoskeleton
insects: tracheae
carry air into the body line and strengthened with rings of chitin
insects: tracheoles
- branch from tracheae no chitin
- air moves along by diffusion to all tissues
specialisations of insects
- high SA of tracheoles
- moist walls
- tracheal fluid limits penetration of air
Why do multicellular organisms require transport systems
- higher metabolic demands
- small sa :v ration and large diffusion distances
- molecules needed in different places to where they’re made (hormones)
Open circulatory system
Small amounts of vessels that contain transport medium pumped from the heart to the body cavity at low pressure
Closed circulatory system
Blood enclosed in vessels doesn’t come into direct contact with cells
Pumped around body by heart
Single circulatory system
Blood pumped from heart all around the body and back
Heart has 2 chambers and passes through 2 sets of capillaries
1 exchanges CO2 and O2, the other exchanges blood to cells
Double circulatory system
Heart has 4 chambers
2 separate circulations
Blood passes heart twice per circuit
Ox and deox blood seperate
Elastic fibres
Stretch and recoil
Provide vessels with flexibility
Smooth muscle
Contract and relax
Changes size of the lumen
Collagen
Structural support
Maintains shape and volume
Arteries
Narrow lumen maintains a high blood pressure
Thick outer collagen layer prevents rupture under high pressure
Inner muscle and elastic layer controls pulse flow
Arterioles
Link arteries to capillaries
Constrict and dilate to control blood flow at individual organs
Capillaries
Narrow diameter
Low blood flow 1rbc allowing time for exchange
1 cell thick wall
Leaky walls allow plasma and dissolved solutes to leave blood
Veins
Wide lumen maximises blood flow back to heart
Thin wall mostly collagen carries low pressure blood
Valves prevent back flow and pooling
Pulse lost at capillaries
Venules
Link capillaries and veins
Prevention of backflow
Valves
Muscle contraction
Diastole
Heart relaxes
Semilunar valves close (dub)
Atria and ventricles fill with blood increasing pressure
Av valves open
Atrial systole
Atria contract
Blood travels from atria to ventricles through AV valve
Ventricular systole
Atria relax ventricles contract
Av valves close (lub)
Blood moves from ventricle to aorta/pulmonary artery through open SL valves
