Please enable JavaScript.
Coggle requires JavaScript to display documents.
3.1&3.2 - Coggle Diagram
3.1&3.2
lesson 5: human gas exchange system
nasal cavity
mouth
epiglottis
oesophagus
larynx
trachea
bronchi
bronchioles
alveoli
pleural cavity
pleural membrane
diaphragm
ribs and internal and external intercostal muscles
adaptations (above the spec)
trachea
ciliated epithelial tissue sweeps mucus up the trachea
rings of cartilage support/prevent collapse
goblet cells produce mucus - traps dirt and pathogens
bronchi
plates of cartilage support
goblet cells produce mucus which traps dirt and pathogens
cilliated cells sweep mucus up the trachea
bronchioles
smooth muscle can contract to constrict airway or relax to dilate airway
alveoli
alveolar wall made of flattened (squamous) epithelial cells - 1 cell thick
surrounded by elastic fibres which stretch during inhilation and recoil in expiration
surrounded by a network of capillaries
adaptations and explanations
alveoli wall is 1 cell thick- short diffusion pathway from alveoli to capillary
capillaries are very narrow- red blood cells are flattened against the capillary walls so short diffusion distance between alveoli and red blood cells and between respiring cells and red blood cells
alveoli surrounded by a network of capillaries- maintains concentration gradient between alveoli and capillaries so speeds up diffusion of oxygen into cells
breathing ventilates the lungs- lungs are constantly ventilated, have a high concentration of oxygen so there is always a steep concentration gradient
lost of alveoli in each lung- very large total surface area
ventilation and gas exchange
inspiration
external intercostal muscles contract pulling ribs upwards and outwards (internal intercostal muscles contract)
diaphragm contracts
thoracic cavity expands
volume increases therefore pressure decreases
air enters through mouth down the pressure gradient
expiration
internal intercostal muscles contract pulling ribs downwards and inwards (external intercostal muscles relax)
diphragm relaxes
thoracic cavity reduces in size
volume decreases and pressure therefore increases
air is pushed out of the lungs and leaves through the mouth
lesson 2: gas exchange in insects
features of insect exchange system
chitin exoskeleton containing spiracles
trachea
tracheoles, contain fluid at the end
respiring cells
mass transport
muscles in the abdomen contract which squeezes the trachea moving large volumes of air in and out - speeds up gas exchange
down a concentration gradient
oxygen concentration high in atmosphere so diffuses down the trachea/tracheoles so it diffuses down the trachea/tracheoles as the respiring cells at the end up the tracheoles use oxygen in respiration and therefore the oxygen concentration falls, this creates the concentration gradient. same is true for carbon dioxide, the respiring cells produce carbon dioxide in respiration so there is a higher concentration of carbon dioxide at the end of the tracheoles and it diffuses down the trachea to the atmosphere where there is a lower concentration
end of tracheoles filled with water
when the insect is respiring anaerobically lactate is produced which lowers the water potential of the muscle cells, water then moves from the end of the tracheoles into the muscle cells via osmosis. this draws air further into the tracheoles, the final diffusion pathway is gas rather than liquid phase so diffusion is more rapid/ oxygen debt repaid faster
adaptations & explanations
tracheoles are highly branched forming an extensive network of tubes
high surface area & short diffusion pathway for oxygen to diffuse from the tracheoles to respiring cells
tracheoles have a thin wall
short diffusion pathway for oxygen to diffuse from air in tracheoles to respiring cells
trachea are strengthened by rings
prevents collapse of trachea
trachea and tracheoles are mostly air filled
diffusion of gases is faster in air than water/fluid
insect response to exercise
spiracles open more which means a greater volume of air is taken in - making concentration gradient steeper
lactate builds up in respiring muscle cells and reduces their water potential, water moves out of tracheoles and into respiring cells via osmosis- draws more air into tracheoles, oxygen can diffuse faster into respiring cells, oxygen debt repaid faster
pumping of abdomen causes increase then decrease of pressure in tracheoles - intake and outake of air so C02 and 02 can be taken in an out in mass quantities
how are insects adapted to water loss
spiracles can close (mainly at rest)
waterproof exoskeleton
spircales are surrounded by hairs
lesson 1: surface area to volume ratio
equations for surface area to volume ratio
sphere
surface area: 4 x π x r^2
volume: 4/3 x π x r^3
cylinder
surface area:(2 x π x r x h) + (2 x π x r^2)
volume: π x r^2 x h
Ficks' law
rate of diffusion ∝surface area x concentration difference / diffusion distance
diffusion is fastest when
large surface area
large concentration difference
short diffusion distance
why do large organisms need exchange systems
they have a small surface area to volume ratio
this means that the outer surface area is not large enough for all gases to enter the body fast enough to keep the cells alive
the gases have to travel further to the centre of the organism, they don't reach the respiring cells fast enough
exchange surfaces have adaptations to speed up the rate of diffusion
general features of exchange surfaces
selectively permeable membrane
high surface area (convoluted shape)
thin - short diffusion distance
ventilation- maintains concentration gradient
transport system associated with surface to maintain concentration gradient
lesson 3: gas exchange in fish
water intake (inspiration)
opercular valve closes
floor of bucal cavity is lowered
volume increases and pressure decreases
water enters mouth to balance pressure
water expulsion (expiration)
opercular valve opens
floor of bucal cavity raised
volume decreases and pressure increases
water pushed over the gills in opercular caity
counter current flow
the blood and water flow over the gill lamellae in opposite directions
ensures that equilibrium is not reached and that the concentration gradient is maintained along the length of the lamellae
diffusion from water to blood takes place
80% of the oxygen available in the water is absorbed into the blood
adaptations of the gills
lamellae give a large surface area
lamellae surface only one cell thick- short diffusion pathway for oxygen from water to capillaries
each lamellae consists of a network of capillaries
lesson 4: gas exchange in plants
leaves of dicotyledon plants (flowering plant that contains two cotyledons (seed leaves))
adaptations and explanations
leaf is thin- short diffusion pathway to each cell from outside
bottom of the leaf has lots of stomata- no cell is far away from a stomata so short diffusion pathway from outside air to leaf cells
mesophyll layer contains many interconnected air spaces- diffusion is in gas phase- more rapid, large surface area for rapid diffusion into cells
reducing water loss in xerophytes
leaf structure
waxy cuticle
upper epidermis
palisade mesophyll
spongy mesophyll - contains xylem and the phloem in the vascular bundle
lower epidermis - contains stomata and guard cells
xerophytes - plants adapted to living in environments with little water availability
guard cells surrounding stomata close at night to prevent water loss when not photosynthesising
waxy cuticle acts as a waterproof barrier so less water is lost through the root
very few stomata at the top of the leaf/upper epidermis
marram grass
rolled up leaves - protects the lower epidermis from the outside and helps to trap a region of still air within the lead, this region becomes saturated with water vapour so has a high water potential. no water potential gradient between inside and outside - no water lost
thick cuticle
hairy leaves- especially on the lower epidermis, traps still moist air next to leaf surface, water potential gradient between outside and inside of the leaves is reduced.
stomata in pits- traps still moist air next to leaf and reduces water potential gradient.
lesson 6: lung disease
issues with the lungs and how they effect someone
cilia become paralysed
mucus builds up in the airway constricting it and pathogens trapped in the mucus are no longer wafted up the airway meaning they could enter the lungs and cause infection
bronchioles become inflamed by infection
lumen of bronchioles becomes smaller causing constricted airwa, not as much oxygen enters the alveoli so reduced concentration gradient between alveoli and blood/ reduded inhilation and exhalation
alveoli fuse with each other (due to excessive coughing which can cause bursting)
reduced surface area- slower rate of diffusion of oxygen and carbon dioxide
scar tissue forms on walls of the alveoli
thicker walls of alveoli means longer diffusion pathway for oxygen into capillaries and carbon dioxide into alveoli
alveoli walls become less elastic
harder to expel air during expiration meaning concentration gradient of carbon dioxide is less steep between capillaries and alveoli
risk factors for lung disease
smoking
lung infection
air pollution
occupation- jobs that involve dust/asbestos/harmful chemicals
genetic makeup
correlation and causation
reasons for a correlation that may not be causation
coincidence
there is a third intervening factor involved
the causal link may be in the opposite direction e.g does bad mental health cause bad physical health or bad physical health cause bad mental health?
there is a clear correlation between smoking and lung disease, scientists have proved a causal link between smoking and lung disease so we can say that smoking causes cancer