3.1 Exchange and transport Flashcards
Why plants need transport systems
Need substances e.g. water, minerals and sugars
Need to get rid of waste e.g. oxygen
Some materials only obtained from specific parts of plant e.g. minerals in soil
Xylem functions
Transport water and dissolved minerals up the plant
Support
Phloem functions
Transports sugars (glucose) and other assimilates in solution up and down the plant
vascular system positions in roots
xylem (in cross / star shape) at the centre
phloem surrounds xylem’s arms
provides support for the root
vascular system in stems
near the outside
xylem closer to the centre and separated from phloem by cambium
provides “scaffolding” to reduce bending of stem
vascular system in leaves
forms veins
xylem at the top of leaf
phloem under the leaf
factors affecting organisms needing specialised exchange surfaces
size
SA:V ratio
level of activity
how size affects need for specialised exchange surfaces
multicellular organisms have several layers of cells diffusion too slow to enable sufficient supply to innermost cells
how SA:V ratio affects need for specialised exchange surfaces
lower in larger organisms
diffusion not sufficient and will not meet requirements due to larger relative volume
how level of activity affects need for specialised exchange surfaces
cells of active organisms need to respire more
needs a more sufficient supply of nutrients and oxygen to keep up rate of respiration
features of good exchange surfaces
large surface area (more space for molecules to pass through)
thin permeable barrier (reduce diffusion distance)
good constant blood supply (maintains a steep concentration gradient so diffusion occurs rapidly all the time)
cartilage functions and location
prevents airways from collapsing during inspiration
tracheal cartilage is C-shaped to allow flexibility and space for food to pass down oesophagus
found in trachea and bronchi
ciliated epithelium functions and location
lines airways
“wafts” to and fro to move mucus up and out of trachea and down oesophagus
found in trachea, bronchi and bronchioles
goblet cell functions and location
secretes mucus (traps microbes and removed to prevent infection) found in trachea, bronchi and larger bronchioles
smooth muscle functions and location
contracts around airways to control size of lumen
prevents harmful substances from entering lungs
found in trachea, bronchi and bronchioles
elastic fibres functions and location
provides recoil when smooth muscles relax, helps airway to open again
stretches when smooth muscles contract
in alveoli, stretch during inspiration (more volume = more air)
in alveoli, provide recoil to help push out air
rib cage function and location
protects organs in thoracic cavity e.g. lungs and heart
surrounds lungs and heart
internal and innermost intercostal muscles functions and location
can contract during expiration to reduce volume of thorax and lungs (only during exercise or coughing and sneezing)
pressure increases over atmospheric pressure
air rushes out of lungs
found between ribs
external intercostal muscles functions and location
elevates ribs (via contracting) during quiet and forced inhalation
increases thoracic volume
decreases pressure lower than atmospheric pressure
air rushes into lungs
found between ribs
diaphragm functions and location
contracts and flattened during inhalation, allowing lungs to move down
increases thoracic volume
decreases pressure lower than atmospheric pressure
air rushes into lungs
found under lungs
inspiration method
diaphragm contracts and moves down and becomes flatter (displaces digestive organs downwards)
external intercostal muscles contract and raise ribs
volume of chest cavity increased
pressure in chest cavity drops below atmospheric pressure
air moves into lungs
expiration method
diaphragm relaxes and pushed up by displaced digestive organs underneath
external intercostal muscles relax and ribs fall
internal intercostal muscles may contract to help (only during exercise or coughing/sneezing)
volume of chest cavity decreased
pressure in lungs rises above atmospheric pressure
air moved out of lungs
vital capacity definition
maximum volume of air they can be moved by the lungs in one breath
dependant on size of person (height), age, gender and level of regular exercise
tidal volume definition
volume of air moved in and our with each breath
normally at rest
usually sufficient to supply all oxygen required in body at rest
residual volume definition
volume of air that remains in the lungs even after forced expiration
breathing rate
how many breaths per minute
oxygen uptake
how much oxygen is used up per minute
can be assumed as the oxygen used up in spirometer
spirometer safety precautions
medical grade oxygen used (there is enough oxygen, no microbes)
water level not too high (doesn’t enter tubes)
disinfect equipment (microbes)
check patients health (e.g. no lung problems)
soda lime (absorb CO2 from chamber)
spirometer validity precautions
nose clip (all air breathed comes from chamber) make sure everything is airtight (no oxygen lost through leaks)
buccal cavity definition
the mouth
countercurrent flow definition
where two fluids flow in opposite directions
maintains constant concentration gradient throughout gill lamellae
gill filament definition
slender branches of tissue that make up gill (primary lamellae)
gill plates definition
folds of the gill filaments to increase surface area (gill plates)
operculum definition
bony flap that covers and protects gills