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biology module 3.1 - exchange and transport - Coggle Diagram
biology module 3.1 - exchange and transport
ventilation in insects
insects have a tough exoskeleton = no gas exchange can occur
open circulatory system (haemolymph is insect blood)
spiracles = small openings along the abdomen of insect, run to trachea, then tracheoles, directly to cells - supplying them with oxygen
trachea = covered in chitin (prevent gas exchange) - provide support and prevent trachea from collapse
tracheoles = NO chitin, large surface area, moist walls, many of them = increased SA:V ratio
tracheal fluid control = fluid at the end of the tracheoles can be withdrawn into the body to allow for a larger SA to be exposed for exchange to occur
mechanical ventilation = wing movements to ventilate the system by opening and closing of spiracles
ventilation in mammals
inspiration
:
diaphragm = contract, move down
external intercostal muscles = contract, move up and out
thoracic volume = increases
thoracic pressure = decreases
expiration
:
diaphragm = relaxes, move up
external intercostal muscles = relax, move down and in
thoracic volume = decreases
thoracic pressure = increases
measuring lung volume - use a peak flow meter, vitalograph or a spirometer
static lower half of the tank and mobile upper half of the tank
when someone breathes into the tank (exhale) the mobile upper half will rise
when someone breaks in from the tank (inhale) the mobile upper half will fall
a tracer is attached to the mobile upper half and produces a trace :
the trace will fall when the tank falls, during inhale
the trace will climb up as the tank rises, during exhale
precautions of the experiment = use fresh soda lime, sterilise mouthpiece, make sure participant is healthy, check there are no air leaks in the apparatus
lung volume graph
tidal volume = volume of air the moves into and out low lungs with a resting breath
vital capacity = largest volume of air that can be inhaled
inspiratory reserve = max volume of air you can breath in above normal inhalation
expiratory reserve = max volume of air you can force out of lungs after nornmal exhale
residual volume = volume of air left in lungs after forced expiration
total lung capacity = vital capacity + residual volume (highest potential amount of air in lungs)
mamalian gas exchange
trachea and bronchi features
:
incomplete cartilage rings = hold trachea open, prevent from collapse, incomplete to allow food to move down the oesophagus
goblet cells and ciliated epithelium = to prevent dust and bacteria entering lungs
smooth muscle and elastic fibres = constrict and dilate airway
bronchioles features
:
NO cartilage
smooth muscle and elastic fibres = hold bronchioles open, control air flow into lungs when muscles contract
cuboidal epithelia cells = allow for some gas exchange
alveoli features
:
lines with a single layer of squamous epithelial cells = very short diffusion distance from capillaries
elastic fibres = allow for recoil to occur, force air our of the alveoli sac
adaptations of the alveoli = very thin walls, good blood supply from capillaries, large surface area (many alveoli), moist walls allow gas to diffolve, surfactant prevents alveoli walls sticking together (phospholipid layer)
need for an exchange surface
features of a good exchange surface :
large surface area = more space for molecules to pass
thin membrane = reduces diffusuion distance
good blood supply = maintain concentration gradient
surface area to volume ratio : small organisms have a large SA:V ratio, larger organisms have a smaller SA:V ratio (inner most cells cannot rely on simple diffusion)
size : large organisms have many layers of cells, the diffusion distance is too long making simple diffusion inefficient
activity level : larger organisms have a higher metabolic rate so require more products for respiration and more waste products need to be removed
ventilation in bony fish
adaptation of fish gills :
many gill lamellae with secondary lamellae increase surface area for exchange
good blood supply
thin layer
changing of buccal cavity volume to pump water over the gills
1) mouth opens and the floor of the buccal cavity lowers
= increases volume the buccal cavity
= pressure in the cavity is lower than oiutside
= causes water to flow in down a pressure gradient
2) opercular valve is shut and the opercular cavity (this contains the gills) expands
= this lowers pressure in the opercular cavity
3) buccal cavity floor moves up
= increased pressure in the buccal cavity vs opercular cavity
= water moves from buccal cavity to opercular cavity, over the gills
4) mouth closes and operculum (bony flap that covers gills) opens and water rushes out
counter-current flow = blood flows in the opposite direction to water to help maintain a constant oxygen concentration gradient - even at the opercular cavity end of the lamellae, there is still a steep enough gradient for oxygen to diffuse from water into the blood