B4 Organising animals and plants Flashcards
what is the problem with a single circulatory system?
the blood looses lots of pressure so when it reaches the organs, it cannot deliver much oxygen
what is the advantage of a double circulatory system?
because the blood passes through the heart twice, the blood travels to the cells rapidly and delivers the oxygen needed
what is the function of the heart?
to pump blood around the body
what key structures are there in the heart? (aside from blood vessles)
the atria - top
ventricles - bottom
valves - separate the atria and ventricles
what are the 4 chambers of the heart and what do they transport?
vena cava - brings deoxygenated blood to the heart
pulmonary artery - transports blood from the heart to the lungs
pulmonary vein - transports blood from the lungs to the heart
aorta - transports blood from the heart to the rest of the body
what do the valves in the heart do?
prevent blood flowing backwards into the atria when the ventricles contract
why is the left side of the heart wall thicker?
they blood from the left side of the heart needs to travel around the entire body. this means the muscular wall needs to exert a greater force on the blood so it is at a higher pressure.
what are the coronary arteries?
arteries which branch out from the aorta into the heart muscle. they provide oxygenated blood to the muscle cells of the heart. the oxygen is used for respiration to provide energy for contraction
what is the pacemaker?
a group of cells in the right atrium which controls the natural resting heart rate
what do arteries carry?
very high pressure blood from the heart to the organs
what is the structure of an artery?
thick muscular wall - withstands high pressure blood
elastic fibres - stretches when a surge of blood passes through and recoils in between surges
what are capilliaries?
blood vessels which transport blood to the cells.
what are the adaptations of capilliaries?
very thin walls - diffusion path is short
what do veins transport?
deoxygenated blood back to the heart from the body
what is the issue with blood travelling in veins?
the blood is travelling slowly at low pressure so could stop or flow backwards
what are the adaptations of veins?
thin wall - pressure is low so a thick wall is not needed
large lumen - allows for a lot of blood to travel
valves - prevent backflow
what are the components of blood?
plasma
white blood cells
red blood cells
platelets
what is the function of blood plasma?
it transports:
- soluble products of digestion
- carbon dioxide
- urea
what is the function of red blood cells?
to transport oxygen from the lungs to the cells
what are the adaptations of red blood cells?
haemoglobin - carries oxygen by turning it into oxyhaemoglobin
no nucleus - can carry more haemoglobin
biconcave disc - greater surface area so more oxygen can diffuse in and out rapidly
what are white blood cells part of?
the immune system
what are the features of a white blood cell?
contains a nucleus - this means it has DNA which encodes the instructions needed for the cell to do its job
what are platelets?
tiny fragments of cells which help the blood clot
what are the uses for donated blood in medicine?
to replace blood lost during injury
extracting platelets to help blood clot
extracting proteins
what are some issues with using donated blood?
the blood has to be the same blood type or the patient could die
diseases can be transmitted in the blood
what are cardiovascular diseases?
diseases of the heart and blood vessels
they are non-communicable
what is coronary heart disease?
when layers of fatty material build up inside the coronary arteries, causing the arteries to narrow.
this reduces the flow of blood through the arteries so there is a lack of oxygen to the heart
what are the treatments for coronary heart disease?
statins - reduces cholesterol in the blood so slows down the rate of build up of fatty material in the arteries
stent - a tube inserted into the artery to keep it open
what are the advantages and disadvantages of statins?
an effective treatment
unwanted side effects
what are the advantages and disadvantages of stents?
blood can flow normally
does not prevent build up in other areas of the arteries
does not treat the underlying causes of the disease
what can happen to valves in the heart?
sometimes not full open so the heart has to pump extra hard
valves can be leaky so the patient feels weak and tired
what can treat a faulty heart valve?
replacing it with a mechanical or biological heart valve?
what are the advantages and disadvantages of a mechanical valve?
lasts a long time
increases risk of blood clots - have to take anticlotting drugs
what are the advantages and disadvantages of a biological valve?
does not last as long - may need to be replaced
no need to take drugs
could be rejected by the body
what is heart failiure?
when the heart cannot pump enough blood around the body
what is the treatment for heart failure?
a donated heart
a donated heart and lungs
what is the issue with a donated heart?
not enough donated hearts for every patient
patient must take drugs to stop the heart being rejected by the body
what is an artificial heart?
a mechanical device which can be used as a temporary solution while a patient waits for a donated heart
it can also allow a damaged heart to rest
what are the disadvantages to an artificial heart?
increases the risk of blood clotting
not a long term solution
how does air enter the lungs? what are the key features of this organ?
through the trachea
rings of cartilage prevent the trachea from collapsing
what structures allow air to enter the lungs?
trachea
bronchi
bronchioles
alveoli
what happens at the alveoli?
it is where gases diffuse in and out of the bloodstream
what are the adaptations of alveoli?
lots of alveoli - lungs have a huge surface area
very thin walls - short diffusion path
good supply of blood - maintains concentration gradient
what does breathing do?
increases the rate of diffusion.
breathing takes away carbon dioxide and brings fresh oxygen to the lungs. this increases the rate of diffusion
what is the epidermis?
a layer of cells on the top and bottom of the leaf
it protects the surface of the leaf
what is an adaptation of the upper epidermis?
it is transparent to let light pass through and let the cells underneath photosynthesise
what does the waxy cuticle do?
it reduces the evaporation of water from the surface of the leaf, preventing the leaf from drying out
what are stomata?
tiny holes in the lower epidermis of the leaf
what is the function of the stomata?
to allow carbon dioxide in to the leaf and oxygen out of it.
they also help control the amount of water vapour that can pass out of the leaf
what is the palisade mesophyll?
the layer of cells under the upper epidermis made up of palisade cells?
what to palisade cells contain?
they contain lots of chloroplasts with chlorophyll in them
this allows the cells to absorb the light energy for photosynthesis?
what is the spongy mesophyll full of?
there are lots of air spaces allowing gases to diffuse in and out of the cell to the palisade cells
what does xylem do?
transports water and dissolved mineral ions from the roots to the stem and the leaves
what does phloem do?
transport dissolved sugars from the leaves to the rest of the plant
what can the sugars made during photosythesis be used for?
respiration straight away
stored as starch
what is translocation?
the movement of sugars and other molecules through phloem tissue
what does meristem tissue contain?
stem cells that can differentiate
what is transpiration?
the loss of water through the leaves by evaporation through the stomata
describe the transpiration stream
water begins to evaporate from the cells inside the leaf.
this water vapour is then diffused into the spaces in the spongy mesophyll and eventually out of the leaf through the stomata.
water from the xylem then travels to the leaf to replace the lost water.
water is then drawn into the root hair cells and up into the xylem vessels into the leaf
why is transpiration important?
it brings water to leaf - water is needed for photosynthesis
transports dissolved mineral ions
evaporation cools the leaf
how does transpiration differ with temperature?
the rate of transpiration is greater at higher temperatures.
this is because evaporation is faster
how do dry, not humid conditions affect transpiration?
it is faster
this is because evaporation takes place more quickly
how do windy conditions affect transpiration?
the rate increases
this is because wind removes water vapour so more water can evaporate
what happens to the rate of transpiration when the light intensity increases?
the rate of transpiration increases
this is because high light intensity increases the rate of photosynthesis so the stomata open to allow carbon dioxide to enter.
this allows water vapour to pass out of the leaf
what happens to photosynthesis if the stomata are closed?
the plant cannot photosynthesise as no CO2 is allowed into the leaf
