Save
Miss Estruch
Topic 3
Save
Share
Learn
Content
Leaderboard
Learn
Created by
Paul Evangelou
Visit profile
Cards (94)
Surface area
to
volume
ratio: The
surface area
of an organism divided by its
volume
the larger the organism, the
smaller
the ratio
Factors affecting gas exchange:
diffusion distance
surface area
concentration gradient
temperature
Ventilation
:
Inhaling and exhaling in humans
controlled by
diaphragm
and
antagonistic
interaction of internal and external
intercostal muscles
Inspiration
:
External intercostal muscles contract and internal relax
pushing ribs up and out
diaphragm contracts and
flattens
air pressure in lungs drops
below
atmospheric pressure
as lung volume increases
air moves in
down
pressure gradient
Expiration
:
External intercostal muscles relax and internal contract
pulling ribs down and in
diaphragm relaxes and domes
air pressure in lungs increases
above
atmospheric pressure
as lung volume decreases
air forced out
down
pressure gradient
Passage of gas exchange:
Mouth / nose -> trachea -> bronchi -> bronchioles -> alveoli
crosses
alveolar epithelium
into
capillary endothelium
Why large organisms need specialised exchange surface?
They have a small
surface area
to
volume
ratio
higher
metabolic rate
- demands efficient gas exchange
specialised organs e.g. lungs / gills designed for exchange
Fish gill anatomy:
Fish gills are stacks of
gill filaments
each filament is covered with
gill lamellae
at right angles
How fish gas exchange surface provides large surface area?
Many
gill
filaments
covered in
many
gill lamellae
are positioned at right angles
creates a large surface area for efficient
diffusion
How tracheal system provides large surface area:
Highly
branched
tracheoles
large number
of tracheoles
filled
in
ends
of tracheoles moves into tissues during exercise so larger surface area for gas exchange
Fluid-filled
tracheole
ends:
Adaptation to
increase movement
of gases
when insect flies and muscles respire anaerobically -
lactate
produced
water potential
of cells lowered, so water moves from tracholes to cells by
osmosis
gases diffuse
faster
in air
How do insects limit water loss:
Small surface area to volume ratio
waterproof
exoskeleton
spiracles can open and close to reduce water loss
thick
waxy cuticle
- increases diffusion distance so less evaporation
Dicotyledonous
plants leaf tissues:
Key structures involved are mesophyll layers
(
palisade
and
spongy
mesophyll)
stomata
created by
guard cells
Gas exchange in plants:
Palisade mesophyll
is site of
photosynthesis
oxygen produced and carbon dioxide used creates a
concentration gradient
oxygen diffuses through air space in spongy mesophyll and diffuse out
stomata
Role of
guard
cells:
swell -
open
stomata
shrink -
closed
stomata
at night they shrink,
reducing
water
loss
by
evaporation
Xerophytic
plants:
Plants adapted to survive in
dry environments
with
limited water
(e.g. marram grass/cacti)
structural features for efficient
gas
exchange
but limiting water loss
Adaptations of
xerophyte
:
Adaptations to trap moisture to
increase humidity
-> lowers
water potential
inside plant so less water lost via osmosis:
sunken
stomata
curled
leaves
hairs
thick cuticle
reduces loss by evaporation
longer
root network
Locations of carbohydrate digestion:
Mouth
->
duodenum
->
ileum
Locations of protein digestion:
Stomach
->
duodenum
->
ileum
Endopeptidases
:
Break
peptide bonds
between amino acids in the
middle
of the chain
creates more
ends
for
exopeptidases
for efficient
hydrolysis
Exopeptidases
: Break
peptide bonds
between amino acids at the
ends
of polymer chain
Membrane-bound
dipeptidases
: Break
peptide
bond between two
amino acids
Digestion of
lipids
:
Digestion by
lipase
(chemical)
emulsified by
bile salts
(physical)
lipase produced in
pancreas
bile salts produced in
liver
and stored in
gall bladder
Role of
bile salts
:
Emulsify lipids to form tiny droplets and
micelles
increases
surface area
for lipase action -
faster hydrolysis
Micelles:
Water soluble vesicles
formed from fatty acids, glycerol, monoglycerides and bile salts
Lipid
absorption:
Micelles
deliver
fatty acids
,
glycerol
and
monoglycerides
to
epithelial
cells
of ileum for absorption
cross via
simple diffusion
as lipid-soluble and non-polar
Lipid
modification:
Smooth
ER reforms monoglycerides / fatty acids into
tryglycerides
golgi apparatus
combines tryglycerides with proteins to form vesicles called
chylomicrons
How lipids enter blood after modification:
Chylomicrons move out of cell via
exocytosis
and enter
lacteal
lymphatic vessels
carry chylomicrons and deposit them in bloodstream
Glucose
and
amino acids
are absorbed via
co-transport
in the
ileum
Haemoglobin
(Hb):
Quaternary structure
protein
2
alpha chains
2
beta chains
4 associated
haem groups
in each chain containing
Fe2+
transports
oxygen
Affinity of
haemoglobin
: The ability of
haemoglobin
to
attract
/
bind
to
oxygen
Saturation
of
haemoglobin
: When haemoglobin is holding the
maximum amount
of
oxygen
it can hold
Loading / unloading of haemoglobin:
Binding
/
detachment
of oxygen to haemoglobin
also known as
association
and
disassociation
Oxyhaemoglobin dissociation curve:
oxygen is
loaded
in regions with
high partial pressures
(alveoli)
unloaded in regions of low partial pressure (respiring tissue)
Oxyhaemoglobin dissociation curve shifting
left
:
Hb would have a
higher affinity
for oxygen
load more
at the same partial pressure
becomes
more saturated
adaptation in
low-oxygen
environments
e.g. llamas/ in foetuses
Bohr
effect:
High
carbon dioxide
partial
pressure
causes oxyhaemoglobin curve to shift to the
right
Oxyhaemoglobin dissociation curve shifting
right
:
Hb has
lower affinity
for oxygen
unloads more
at the same partial pressures
less
saturated
present in animals with
faster metabolisms
that need more oxygen for respiration e.g. birds/rodents
Closed
circulatory system
: Blood
remains
within
blood vessels
Name different types of blood vessels:
Arteries
,
arterioles
,
capillaries
,
venules
and
veins
Capillary endothelium
:
Extremely
thin
one
cell thick
contains
small
gaps for small molecules to pass through (e.g. glucose, oxygen)
See all 94 cards