Gas exchange Flashcards
how does distance diffusion, SA, volume and SA:vol ratio vary with increasing organism size
- diffusion distance increases with increasing organism size
- SA increases by factor ^2
- Vol by a cubed factor
- SA:Vol ratio decrease as distance to diffuse to middle of organism increases making it impossible to get enough oxygen the body needs from this
how does the level of activity of an organism related to demand for oxygen and glucose
as activity increases, the need for energy increases. Requires a higher rate of respiration so a higher demand for oxygen and glucose.
how is volume related to the demand and surface area is related to supply and why adaptations are needed for supply to meet demand as organisms increase in size
- as volume increases demand increases as more respiring cells needing oxygen and glucose
- as SA increases it increases supply as more diffusion area
- simple surface area not adequate for large volumes so adaptations occur to increase SA for larger exchange surfaces
why do organisms need specialized exchange surfaces
larger volumes so their SA:Vol ratio is too small to meet demand for high activity of organisms
4 features of efficient exchange surfaces
- thin membrane - decrease diffusion distance
- large surface area - overcome SA:Vol ratio
- good blood supply - maintains high conc gradient
- well ventilated - helps to maintain high conc gradient
state Fick’s law
Rate of diffusion is proportional to
(SA x conc. gradient)/Thickness of Barrier
Ventilation and blood supply affect conc. grad.
describe the structure and function of the nasal cavity
large surface area with good blood supply
hairy lining which secretes mucus to protect delicate lung tissue from infection
moist surface increases humidity to prevent evaporation at exchange surface
describe the structure and function of the trachea, bronchi and large bronchioles
cartilage rings to keep open airways open and stop them collapsing (small bronchioles have no cartilage)
cilia and goblet cells work together to trap mucus and sweep it away
smooth muscle and elastic fibres allow diameter of tube to change e.g. o increase vol of oxygen
describe the structure and function of the alveoli
- tiny sacs - main gas exchange surface in the body
200-300 micrometers - flattened epithelial cells - thin diffusion distance
elastic fibres allow alveoli to stretch as air is breathed in when return to resting size they squeeze air out - elastic recoil - good blood supply - capillaries only 1 cell thick maintain conc gradient and short diffusion distance
- squamous epithelial - thin and moist - dissolve gases for increased diffusion
how do the cilia and goblet cells of the trachea and bronchus work together to protect the lungs
goblet cells produce mucus which traps dust particles etc. from the air, cilia then work to sweep out of the trachea to be swallowed and digested protecting lungs from infection
what is the importance of elastic fibres and lung surfactant in the function of the alveoli
elastic fibres - spring back to normal size to push air depleted of oxygen out of lungs
lung surfactant - reduces surface tension - prevent alveoli from sticking together when breathing in
how is the mammalian gaseous exchange system adapted to be efficient
large surface area - lots of alveoli
good blood supply - network of capillaries
ventilated - maintains conc gradient
short distance - thin + 1 cell thick
define the terms breathing, ventilation and gas exchange
is the behavior/ action involves muscle contraction and relaxation
ventilation - flow of air in and out of lungs
gas exchange - diffusion of oxygen and carbon dioxide in and out of the blood
describe the process of inspiration/breathing in
an active process
active process
1. diaphragm contacts and flattens
2. external intercostal muscle contact moving rib cage upwards and outwards
3. volume of thorax increases and so pressure decreases
4. due to lower pressure in thorax than outside air is brought into lungs equalizing the pressure.
describe the process of normal expiration/breathing out
passive process
- diaphragm relaxes returning to domed shape
- external intercostal muscles relax so ribs move downwards and inwards
- elastic fibres of alveoli relax
- volume of thorax decreased and so pressure increased to more than atmospheric air so air drawn out of lungs
how is forced expiration different from normal expiration?
uses energy so active process
- internal intercostal muscles contract pulling ribs down hard and fast
- abdomen muscles contract bringing diaphragm up to increase pressure rapidly
state 3 pieces of equipment used to measure the functioning of the lungs
- peak flow meter - used to measure rate air can be forced out of the lungs often used on people with asthma
- vitalographs - more sophisticated peak flow meter - breath out as hard and as fast as they can into mouthpiece produces a graph with how forced and quick air way breathed out - forced expiratory volume in 1 second
spirometer - floating chamber on water which is connected to a pivot so it can move when you inhale and exhale drawing a trace on a rotating drum.
define tidal volume
volume of air moved into or out of the lungs in one normal breath when normally breathing (500cm^3)
define vital capacity
maximum volume of air that can be exchanged in one breath
define inspiration reserve volume
maximum extra volume that can be inhaled after a normal breath in