B4 Flashcards
Organising animals and plants
What are the main components of the blood ?
- red blood cells
- plasma (straw coloured liquid)
- white blood cells
- platelets
What is the purpose of plasma in the blood ?
- acts as a transport medium and makes up the majority of the blood
- carries the white and red blood cells, platelets AND waste products and nutrients
[] carries CO(2) to the lungs to be diffused in and breathed out
[] carries oxygen and nutrients to muscles in the body
[] carries urea to the kidneys
What is the purpose of red blood cells in the blood ?
- transport oxygen around the body
[] do this through the reversible reaction of oxygen binding to haemoglobin (oxygen + haemoglobin <-> oxyhaemoglobin)
[] have no nucleus, so more space for haemoglobin (red pigment)
[] biconcave, increasing surface area for easier reaction with oxygen
What is the purpose of platelets in the blood ?
- cell fragments that coagulate at wound sites and trigger the formation of insoluble fibrin proteins to keep the clot stable - also captures red blood cells at the clot site to make it even more stable
- the clot eventually dries into a scab
[] protects from pathogens whilst the would heals underneath
[] makes sure you don’t bleed to death
[] no nucleus (formed from stem cells producing larger proto-platelets that break up into functioning platelets in the bone marrow)
What is the purpose of white blood cells in the blood ?
- protect the body against pathogens and disease, forming part of the immune system
[] phagocytosis (engulf pathogens and destroy them)
[] antibody production (latch onto proteins external to bacteria and unravel them to destroy the pathogen)
[] antitoxin production (neutralise harmful toxins produced by bacteria)
What are the structural features and functions of the arteries ?
function:
- pump blood AWAY from the heart to the body
structure:
- thick walls with thick layer of elastic and muscle fibres
[] keep the blood in the arteries under immense pressure to make it travel far to limbs around the body
[] muscle fibres contract and force blood through
- small lumen
[] keeps the blood under pressure - makes arteries have a pulse (stretches open and then closed when blood is forced through)
What are the structural features and functions of the veins ?
function:
- bring blood TOWARDS heart
[] skeletal muscles surrounding the veins contract to squeeze blood in the right direction
structure:
- relatively thin walls
[] no muscle fibres needed as veins don’t have a pulse
- have valves
[] open then close when blood flows through (prevents backflow of blood)
- wide lumen
[] allows blood to travel at low pressure and flow towards the heart
What are the structural features and functions of the capillaries ?
functions:
- link arteries and veins
- allow oxygen, soluble products of digestion and waste products to diffuse into the blood stream where they are transported to where they need to be
structure:
- very thin walls only one cell thick
[] short diffusion distance makes diffusion of different molecules in/out of the blood much more efficient
- extremely narrow lumen and tiny vessel
[] allows space for many large networks of capillaries to build up and carry out diffusion or active transport in certain places much more quickly and efficiently
[] increases surface area of the blood inside the capillary, making diffusion much more efficient
What is the double circulatory system and why is it important ?
- vital for warm blooded, larger mammals
[] allows circulatory system to be much more efficient (deoxygenated blood oxygenated in the lungs then returned to the heart continually to be quickly pumped to the rest of the body
[] maximum efficiency is needed for large animals’ circulatory systems to keep all limbs, no matter how far from the heart, supplied with oxygen and vital nutrients - one faction of the system goes to the lungs and oxygenates blood before bringing back to heart, then heart pumps oxygenated blood to body
Where in the heart are pacemaker cells located ?
right atrium
Describe the (11) main structures in the heart, their locations in the heart and their purposes
- thicker muscle wall on left side
[] left side of heart pumps blood to body; needs lots of pressure and thus needs increased force via muscle contraction when pumping blood - pulmonary vein
[] carries freshly oxygenated blood from lungs to heart
[] enters to the left atrium - pulmonary artery
[] carries deoxygenated blood from heart to lungs
[] top of right side - vena cava
[] vein that brings deoxygenated blood to body
[] right of heart, entering right atrium - aorta
[] artery that pumps oxygenated blood to the body
[] top of left side - right atrium
[] receives deoxygenated blood from the vena cava
[] when heart contracts, blood is forced from here to the right ventricle - left atrium
[] receives oxygenated blood from the pulmonary vein
[] when heart contracts, blood forced down into left ventricle - left ventricle
[] receives blood from left atrium when forced down by contraction
[] when lower half of heart contracts, forces blood up into the aorta - right ventricle
[] receives blood from right atrium when forced down by contraction
[] when lower half of heart contracts, forces blood up into the pulmonary artery - heart valves
[] open and close when blood is forced through from an atrium to a ventricle/a ventricle to an artery
[] prevent the backflow of blood and make circulation more efficient - pacemaker cells
[] right atrium
[] coordinate muscle contractions of the heart via electrical impulses to keep blood flowing steadily
How is muscle tissue of the heart supplied with oxygen and nutrients to be able to contract ?
coronary arteries
What is coronary heart disease (CHD) ?
build-up of fatty material (LDL cholesterol deposits) in coronary arteries, restricting blood flow and thus supply of oxygen/nutrients to the muscles in the heart
[] pain caused
[] often leads to heart attacks when the heart muscles cannot contract properly
How is CHD treated ?
- statins
[] drugs that reduce blood cholesterol levels and slow the deposition of fatty material in the arteries - stents
[] metal meshes inserted into the arteries and expanded to keep them open so blood can flow through - bypass surgery
[] replacing very badly blocked arteries with fragments of veins from around the body
Describe the advantages and disadvantages of stents, statins and bypass surgery in treating CHD
bypass surgery
- disadvantages:
[] expensive
[] risk of general anaesthesia during surgery
[] risk of infection during the open heart surgery
- advantages:
[] permanent, no replacement needed
[] can live a normal life
[] immunosuppressants not needed due to artery being reconstructed with own tissue
stents
- disadvantages:
[] the metal may induce thrombosis (causing heart attack)
[] have to take blood-thinning drugs everyday to prevent clotting/thrombosis - inconvenient and expensive
[] chance of the stent re-narrowing and thus needing another stent procedure
- advantages:
[] procedure can be done without the use of general anaesthesia (no risk)
[] quick recovery time for procedure
[] no open-heart surgery needed, so less chance of infection of the heart
[] overall risk of complications is low
statins:
- disadvantages:
[] drug has to be taken regularly and for whole life - inconvenient and expensive
[] do not remove LDL cholesterol deposits already present in arteries, so are only useful for those at risk of CHD sometime in the future - also do not completely stop the deposits
[] may cause side effects for certain individuals
- advantages:
[] effective at reducing LDL cholesterol levels in blood (the cholesterol type responsible for CHD)
[] increases the amount of “good” cholesterol (HDL) which helps to remove LDL cholesterol from the blood - associated with lower risk of heart disease etc.
[] no surgical risks like general anaesthesia unlike bypass surgery, and no risk of infection from improperly sterilised medical equipment like with stents
What are the problems with leaky heart valves and how can they be treated ?
problems:
- become stiff or don’t open fully over time due to withstanding tremendous pressure within the heart
- makes circulation less efficient
- can make people breathless and without treatment is fatal
treatment:
- replacement of faulty valves
[] mechanical replacement valves
[] animal replacement valves
Describe the disadvantages/advantages of treating leaky heart valves with biological replacement valves vs. mechanical replacement valves
biological
- advantages:
[] work extremely well - patient can live normal life
[] no medication needed - no additional costs
- disadvantages:
[] need replacement every 10-15 years as can also stiffen like the original valves (increased risks associated with surgery)
[] surgical risks like general anaesthesia whilst operating and risk of infection from open heart surgery
mechanical
- advantages:
[] last extremely long time so replacement surgeries are rare
[] don’t need to wait for a donor animal or human
- disadvantages:
[] surgical risks like general anaesthesia whilst operating and risk of infection from open heart surgery
[] medication needed for the rest of patient’s life to prevent blood clots surrounding the metal (thrombosis) - expensive and inconvenient
What are the problems with faulty pacemaker cells and how can they be treated ?
problems:
- if heart beats too slowly, not enough oxygen/nutrients supplied to body
- if heart beats too quickly, can’t properly pump blood
treatment:
- artificial pacemaker
[] implanted into chest + sends properly timed electrical signals to heart to stimulate it to beat steadily
[] weighs only 20-50g
[] modern pacemakers only are activated when needed and some stimulate heart to beat faster during exercise
[] allows patient to live relatively normal life (though there need to be regular check-ups etc.)
What are the problems with heart failure/diseased hearts and how can they be treated ?
problems:
- heart can be too tired/weak to properly pump blood
- need heart transplant
[] BUT donors are rare and the person often dies whilst waiting
treatment:
- whilst waiting for heart transplant donor, artificial heart can be used
[] keeps strain off of heart for pumping blood so can recover etc.
[] are extremely expensive
[] risk of thrombosis (need to take blood thinners to prevent)
[] patients can live relatively normal lives whilst waiting for donors
Describe the organs/muscles present in the ventilation/gas exchange system in the human body
- lungs
[] contain two bronchi (which have many bronchioles with alveoli on the ends) - intercostal muscles
- ribs
- diaphragm
- trachea (windpipe)
Explain how you breathe out
- intercostal muscles relax
[] ribs move down and inwards - diaphragm relaxes and moves up
- volume in chest cavity decreases and so pressure of air in chest decreases
- air is forced out of the lungs due to the higher pressure external to the lungs
Explain how you breathe in
- intercostal muscles contract
[] ribs move up and out - diaphragm contracts and moves down
- volume of chest cavity increases so pressure of chest cavity increases
- air is forced into the lungs as pressure is higher inside than external to the lungs
Describe adaptations of the alveoli for efficient gas exchange
- good (deoxygenated) blood supply
[] high conc. of oxygen from newly inhaled air diffuses into blood
[] high conc. of CO(2) diffuses into alveoli (low conc.)
[] maintains concentration gradient - good ventilation
[] maintains steep concentration gradient for efficient diffusion - walls are 1 cell thick
[] short diffusion distance raises rate of diffusion - spherically shaped
[] large surface area, so diffusion more efficient
Describe the internal structures in a plant leaf
- waxy cuticle
[] waterproofs leaf and protests from loss of water - epidermal tissue
[] protect leaf and secrete wax to replenish the waxy cuticle
[] are relatively transparent to let light through to the photosynthetic cells below - palisade mesophyll
[] contains many palisade cells which have many chloroplasts to carry out photosynthesis - spongy mesophyll
[] many air spaces between the cells so that gases can flow quickly around the leaf for efficient gas exchange
[] increases surface area - vascular bundle + veins
[] carry water to palisade mesophyll for photosynthesis and nutrients to other parts
[] carry products of photosynthesis away from palisade mesophyll - stomata
[] gaps in the leaf so that oxygen and carbon dioxide can be taken in/out of the leaf - guard cells
[] open/close the stomata based on the plant’s needs and to prevent water loss via water vapours
What is translocation ?
the movement of dissolved sugars around a plant by active transport via the phloem
Why do young trees have protective plastic collars around their trunks ?
to stop deer and other wildlife from eating the bark and destroying the ring of phloem below it as well as the xylem in the wood (if this happens, transport to the rest of the tree will stop and it’ll die)
Describe the route of the transpiration stream in plants
- water moves into the roots by osmosis
- water moves up from roots into the stem in the xylem
- water moves up through the stem and into the leaves of the plant to replace evaporated water
- water evaporates through the stoma of the leaf, pulling more water from the stem upwards to replace it and repeating the cycle
Which factors increase the rate of transpiration ?
ANYTHING THAT INCREASES RATE OF EVAPORATION, DIFFUSION OR PHOTOSYNTHESIS WILL INCREASE RATES OF TRANSPIRATION
- heat/temperature
- light intensity
- dry air
- wind
[] maintains conc. gradient
How do plants prevent too much water loss via transpiration and evaporation ?
- waxy cuticle
[] is thicker often in hotter climates - stomata are situated on underside of lead
[] not directly exposed to wind or light so lessens transpiration - wilting when losing water too rapidly
[] decreases surface area for transpiration to take place however harms photosynthetic levels in plant - stomata closing when losing water too rapidly
[] however opens plant to risk of overheating as well as stopping photosynthesis (no CO(2) can get into plant)
Describe how to use a bubble potometer to measure the rate of transpiration in plants under different light intensities
- submerge the potometer in water
- cut the stem of a leafy plant underwater and fit it to the potometer underwater
- lift the potometer out of the water and close the reservoir tap immediately
- place the end of the capillary tube in a beaker of water
- smear Vaseline on all junctions of the potometer (where the plant is connected to the potometer) to prevent leakage or evaporation of water through these parts
- dry the leaves of the plant gently with tissue
first location = sunny windowsill
- introduce an air bubble into the capillary tube by lifting it out of the beaker and then placing it back after a few seconds
- wait 5 minutes for the plant to equilibrate and for the air bubble to enter the graduated section of the tube
- record the start position of the air bubble
- leave for 20 minutes and record end position of the air bubble
- open the reservoir tap slowly and allow the air bubble to be pushed back into the beginning of the graduated section
- repeat measurement 2 more times and record average distance travelled in 20 minutes
[] also calculate rate of transpiration
second location = dark cupboard
- repeat all steps from the first location
third location = back of a room with partial light
- repeat all steps from the first location
- compare results in all three places
- should find that rate of transpiration was highest in sunny windowsill
How can you improve the accuracy of measuring the rate of transpiration ?
use a mass potometer instead of a bubble potometer
