B2.2 - transport and blood Flashcards
why are tapeworms able to survive with a single circulatory system?
- has a high surface area to volume ratio
- nutrients can dissolve quick enough to sustain the organism
why do multicellular organisms require adapted exchange surfaces?
- because their surface area to volume ratio is low
- so diffusion cannot occur fast enough to meet the organism’s demand
how have the lungs adapted to maximise the rate of diffusion into the bloodstream?
lungs contain lots of alveoli (increase surface area)
how have alveoli adapted to maximise diffusion? (4)
- steep concentration gradient (ventilation through air)
- thin alveoli walls (one cell thick - easy diffusion)
- high surface area to volume ratio
- capillaries close to the alveoli (less distance needed to travel)
how is the small intestine adapted to maximise diffusion rate? (1)
finger like villi on walls
how do villi affect the rate of diffusion in the small intestine?
increase surface area
with microscopic villi on villi themselves
give examples of exchange surfaces and transport systems
- alveoli
- villi
- xylem
- phloem
what is the function of the circulatory system?
transport substances around the body to the cells that need them
what is the hollow cavity in the centre of blood vessels called?
lumen
state features of an artery (3)
- thick outer wall (high pressure from heart)
- thick layer of muscle + elastic fibres (to contract)
- small lumen
state features of a vein (physical features)
- thin outer wall
- thin layer of muscle + elastic fibres
- large lumen
- valves (stop blood flowing wrong way)
state features of capillaries
- small lumen (allows small diffusion distance)
- single wall of cells
(maximise diffusion through semipermeable walls)
what is the function of arteries?
carry blood away from the heart
what is the function of veins?
return blood to heart
why do veins have valves?
- prevent back flow
- since blood is flowing at low pressure, it is more likely to flow backwards
function of capillaries?
link arteries and veins in tissues + organs
how do arteries work?
- muscle fibres contract to push blood forward
- then relax (and then the lumen expands)
what does the double circulatory system mean?
(how does that affect the pressure compared to a single circulatory ststem)
and what does it allow the body to do?
- for each journey around the body, blood is pumped twice
(so pressure is higher than single circulatory system) - materials are transported quickly around body
why are alveoli moist?
so gases can diffuse across the cell membrane (easily) as gases will dissolve?
what is the use of haemoglobin?
binds to oxygen from the lungs
transports oxygen around body
what specifically travels in the phloem?
cell sap (sugars/salts/animo acids)
does transpiration or translocation happen in the phloem?
translocation (sugars moved around)
why are cardiac muscles special?
they contract without receiving a nerve impulse from the brain
what does the vena cava do?
brings deoxygenated blood to the heart from the body
what does the pulmonary artery do?
takes deoxygenated blood from the heart to the lungs
what does the pulmonary vein do?
brings oxygenated blood to the heart from the lungs
what does the aorta do?
carries oxygenated blood from the heart around the body
how is the heart depicted? (ie. ventricles on which sides)
from the patient’s point of view
so looking down at your heart your right, would be their left
what are the two smaller chambers at the top of the heart called?
atria
what are the two small chambers at the bottom of the heart called?
ventricles
what separate the chambers and prevent back flow?
valves
describe the process how deoxygenated blood becomes oxygenated
1) deoxygenated blood enters right atrium via vena cava
2) is then pumped to right ventricle when heart beats
3) pulmonary artery takes it to the lungs
4) alveoli diffuse co2 and and o2 in
5) pulmonary vein carries oxygenated blood to left atrium
6) blood pumped to left ventricle
7) aorta carries blood away to rest of body
why is the right ventricle wall thinner than the left ventricle?
left ventricle wall is thick to push blood around body at high pressure through aorta
state adaptations of red blood cells, and explain the functions
- biconcave shape (increases surface area to volume ratio, diffusion occurs faster)
- no nucleus (maximum space for oxygen)
- protein haemoglobin (binds to oxygen in alveoli and carries it around body)
- small (to fit though capillaries)
state adaptations of white blood cells, and explain the functions (4)
- can change shape easily (to engulf pathogens)
- large cell
- contain nucleus
- creates antibodies (fight antigens on pathogens)
state the function of platelets
- help blood clot to prevent pathogens from entering body
state features of plasma
- straw coloured liquid
- 90% is water
what is the function of plasma?
transport materials
- digested materials (animo acids/glucose)
- waste (CO2)
- hormones
- antibodies
what does the xylem tissue do?
transports water + mineral ions from roots to rest of plant
how is water taken in from the roots?
osmosis
how are mineral ions taken in through the roots?
active transport
what does the phloem tissue transport, and where to?
- dissolved sugar molecules/ soluble food molecules
- from leaves to rest of plant
why are sugars taken to meristems?
- making new plant cells
- storage tissue in roots
how do the vascular bundles provide support in the leaf?
- form network to support softer leaf tissue
what do phloem and xylem make up together?
vascular bundles
state features of the xylem
- dead cells
- cell wall thickened by lignin (support)
- one way
- no sieve plates (cells completely break down when dead)
state features of the phloem
- live cells
- sieve plates (live cells do not completely break down)
- two way flow
- small holes in sieve plates (sugar to pass through)
how do the vascular bundles provide support in the stem?
- located around outer edge
- prevent stem from bending in wind
how do the vascular bundles provide support in the roots?
- in centre
- root acts like anchor
- root can bend as plant moves in wind
define transpiration
loss of water from plant’s leaves
describe the process of transpiration
1) water moves from soil to roots
2) water moves from root to stem
3) water moved through stem to leaves (replace water lost)
4) water evaporates from leaves (open stomata)
what is the transpiration stream?
constant flow of water from roots -> xylem -> leaves
how does water enter the xylem from root hair cells?
travels from cell to cell until reaches centre of root (where xylem is)
what controls the stomata from opening and closing?
guard cells
what happens while the stomata are open?
1) water evaporates from cells inside leaves to air space (in leaves)
= CHANGE IN CONCENTRATION GRADIENT
2) water diffuses out of leaf into air
what feature on a leaf prevents uncontrollable water loss
waxy waterproof layer (cuticle)
how is water resupplied to the leaves? (and don’t say transpiration)
pressure difference (sucking on a straw)
- pressure low at leaves
- pressure high at roots
- water moves from high pressure to low pressure *
what causes plants to wilt?
- water lost faster than taken in
how does wilting help but not help a dehydrated plant at the same time?
pos - surface area reduced for evaporation
- stomata closes (less water loss)
neg - stomata closed prevents co2 for photosynthesis
- so cannot produce enough energy
what tool can you use to measure how quickly a plant shoot takes + loses water?
potometer (see how much the air bubble moves)
what is the equation to measure the rate of transpiration?
distance travelled (mm)
——————————
time (s)
what 4 factors affect rate of transpiration?
- light intensity
- temperature
- humidity
- wind
how does light intensity affect transpiration?
- stomata stays open in light (so more water evaporates)
INCREASES
when does rate of transpiration reach its maximum rate (light intensity)?
all stomata are open
how does temperature affect transpiration?
- high temp = more evaporated
(diffusion of water vapour increases)
INCREASES
how does air movement affect transpiration?
faster air moves = faster water molecules moved
- increases concentration gradient between air and leaf
INCREASES
how does humidity affect transpiration?
more humidity = more water in air
-> lower concentration gradient
more water in air = less evaporation
DECREASES
