organism exchange Flashcards
surface area to volume ratio
larger the organism= smaller SA:V
Fick’s law is…
rate of diffusion= (SA x difference in conc.)/ length of diffusion path
single celled organisms…
exchange gases across body due to large SA:V
the tracheal system of insects has…
trachea
tracheoles
spiracles
adaptation of insect tracheal system…
gases enter + exit through spiracles
gas exchange through diffusion, CO2 conc. gradient from tracheoles to atmosphere
mass transport- contraction of abdominal muscles moves gases along
in flight, muscle cells respire anaerobically to produce lactate, lowering WP so water moves from tracheoles to cells
more air drawn down in to decreases volume in tracheoles
structure of mass exchange in fish
gill filaments (at right angles to each other to increase SA)
lamellae in gill filaments (deep folds= increases SA)
adaptation of gas exchange in fish are…
lamellae are folded for large SA
lamellae + filaments= thin, increased diffusion rate
use counter current exchange to absorb O2
counter-current principal is…
water and blood flow in opposite direction
ensures a favourable conc/ gradient of O2 is maintained across WHOLE LENGTH of lamellae
dicotyledonous plants…
exchange gas though stomata
guard cells control opening/closing, helps prevent water loss by evaporation
small SA:V
waxy cuticle (waterproof)
hairy leaves trap water vapour (reduce WP gradient)
cuticle rolls to cover stomata
structure of gas exchange in humans
trachea
bronchus
bronchiole
alveolus
diaphragm
lungs
ribs
inspiration
external intercostal muscle contracts, internal intercostal muscle releases
ribs pulled upwards and outwards whilst diaphragm contracts and flattens
increased thoracic volume, decreasing air pressure so air forced into lungs
expiration
external intercostal muscle relaxes, internal intercostal muscle contracts
ribs pulled downwards and inwards, diaphragm relaxes and is pushed back into dome shape
decreases thoracic volume, increasing air pressure so CO2 is forced into atmosphere
alveoli has…
very large SA= higher rate of diffusion
network of capillaries so short diffusion distance
alveolar epithelium is thin
amylase is…
produced in salivary glands/pancreas (secrets into the small intestine)
hydrolyses starch into maltose
membrane bound disaccharides…
present in membrane small intestine
hydrolyse disaccharides (maltose to monosaccharide like glucose)
lipase…
hydrolysis lipids to monoglycerides and fatty acids
present in small intestine
adaptations that help lipase
bile salts made by liver emulsify lipids giving large SA so easily hydrolysed by lipase
products can remain associated with bile to form micelles
micelles travel to ileum, broken down when in contact with epithelium, products can diffuse straight into epithelium
protease…
hydrolyses proteins (polypeptides) into amino acids
3 types: endopeptidases (hydrolyse peptide bonds in the middle region of the polypeptide chain), exopeptidase (hydrolyse peptide bonds on terminal amino acids), membrane-bound dipeptidases (hydrolyse dipeptides into 2 amino acids)
adaptation of amino acids and monosaccharides
co-transport:
1. Na+ and amino acid co-transported from lumen to epithelium
2. K+ actively transported from blood into epithelium
3. amino acid transported into blood via facilitated diffusion
haemoglobin is…
globular protein (4 polypeptide chains, quaternary structure)
each haem group has Fe+ ion
has 4 oxygen binding sites
function- carry O2 through blood to respiring tissues
loading/unloading; oxyhaemoglobin dissociation curve features…
partial pressure= O2 conc.
at lowest part of graph= low affinity, low chance of oxygen loading onto haem
at highest point of graph= high affinity, saturation increases, high chance of O2 loading onto haem
s shaped because= upon binding of first O2 molecule, tertiary structure of haem changes, making 2nd + 3rd binding easier, so saturation increases (conformational change)
Bohr effect is…
CO2 dissolves in blood, forming carbonic acid, lowering blood pH
changes tertiary structure of haemoglobin, so lower affinity
more O2 dissociates at respiring tissues
low affinity= curve shifts to the right
high affinity= curve shifts to left
some species have different haem…
mountain =-dwellers have haem with high affinity so is loaded with O2 at Lowe partial pressure
less O2 available at high altitude so good
foetuses, worms have some myoglobin which has high affinity
circulatory system of mammals
veins= towards heart
arteries away from heart
types of veins and arteries…
vein to hear= vena cava
heart to lungs= pulmonary artery
lungs to heart= pulmonary vein
heart ti body= aorta
vein towards liver= hepatic
vein towards kidneys= renal
structure of the human heart…
enter right atrium via vena cava
tricuspid valve to right ventricle
pulmonary artery to lungs
left atrium
bicuspid valve to left ventricle
aorta to body
adaptation of the human heart…
walls on left are thicker, blood has to be pumped around the whole body, so high muscle power required
atria thin- only pump to ventricles
ventricles thick- pump to lungs and body
cardiac cycle…
cardiac diastole= atria + ventricles relaxed, blood enters atria
pressure rises, so AV valves open, blood flows into ventricles down pressure gradient
article systole + ventricle diastole= atria contract to ensure blood enters ventricles (ventricular diastole)
ventricular pressure slightly incr. shutting AV valves to prevent back flow
ventricular systole= ventricles contract, further incr. ventricular pressure so more than that of pulmonary artery/aorta
semi-lunar valves open so blood flows into pulmonary artery (right-deoxygenated/aorta, left-oxygenated)
double circulatory system…
allows high pressure to be maintained
single system wouldn’t work- large SA of lung capillaries would decrease pressure so less oxygenated blood delivered to tissues
adaptations of arteries
thick muscular layer, so constriction and dilation can control blood volume
thick elastic layer to maintain blood pressure and allow stretch and recoil
thick wall, prevent bursting due to high pressure
adaptations of arterioles
thick muscle layer to restrict blood flow into capillaries
thinner elastic layer and walls
adaptations of veins
thin muscle and elastic layer and wall due to lower pressure
can be flattened easily, helping blood flow to heart, larger SA
valves to prevent back flow
adaptations of capillaries
no muscle/elastic layer
one cell thick
form capillary beds, narrow diameter, short diffusion distance
formation and return of fluid steps
- blood enters from arterioles, resulting in high hydrostatic pressure at arteriole end (start)
- molecules like glucose, amino acids, fatty acids, ions, H2O and O2 forced out (this forms tissue fluid)
- large molecules like protein ramen in capillaries, lowering water potential
- at venue end, low hydrostatic pressure and water potential, so H2O re-enters by osmosis (not all)
- remaining tissue fluid absorbed into lymphatic system, later re-absorbed into capillaries
leaf anatomy
xylem= responsible for movement of water]
H2O absorbed by root hair cells via osmosis
H2O reaches xylem, transported against gravity along long, thick-walled tubes
phloem= transports organic substances by translocation (mass flow hypothesis)
sieve tube elements, companion cells
cohesion tension theory
water is dipolar, so H bonds formed between H2O molecules (cohesion)
results in continuous eater column being created in xylem
H2O transpires, so column is pulled up the xylem (transpiration pull)
puts tension on xylem, making diameter decrease
how can xylem form column?
cells= hollow because they are dead, no end walls
mass flow hypothesis steps…
- organic molecules created by photosynthesis transported to companion cells via facilitated diffusion (source)
- sucrose actively transported into phloem/sieve tube elements by co-transport with H ion
- this decreases WP so H2O enters phloem form xylem via osmosis
- this incr. volume= incr. hydrostatic pressure
- sugars used in respiring cells, incr. WP so they exit by osmosis, decreasing hydrostatic pressure (sink)
- hydrostatic pressure gradient therefore created from phloem to respiring cells
ringing experiment…
- ring of bark along phloem removed from trunk
- trunk swells above removed ring, liquid was found to contain sugar
- showed phloem transported sugars as can’t be transported due to removal of phloem ring
tracing experiment…
- plants provided with radioactive- labelled CO2
- absorbed during photosynthesis to produce sugars, also radioactively- labelled
- samples then cut and placed on X-ray film, detects radioactive material
- section containing radioactive sugars was detected, highlighting where phloem was located
