MOCKS STRUCTURE AND FUNCTIONS IN LIVING ORGANISMS Flashcards
2.2 cells are separated from their surrounding environment by
a cell membrane
2.2 within the cell membrane is the
cytoplasm
2.2 eukaryotic cells have … contained within their cytoplasm
organelles
2.2 organelles are
where specific processes take place within the cell
2.2 what is in the cytoplasm of a eukaryotic cell
nucleus, mitochondria & ribosomes
2.2 plant cells contain the following additional structures
cell wall, chloroplasts & a vacuole
2.3 function of the nucleus
contains genetic material in chromosomes
controls cell division
2.3 function of the cytoplasm
supports cell structure
site of many chemical reactions
contains water and many solutes
jelly-like substance
2.3 function of the cell membrane
holds the cell together
controls substances entering and leaving the cell
2.3 function of the cell wall
gives the cell extra support and defines its shape
2.3 function of the mitochondria
site of aerobic respiration providing energy for the cell
2.3 function of the chloroplasts
site of photosynthesis - provides food for plants
chlorophyll pigment absorbs light energy
2.3 function of the ribosomes
the site of protein synthesis
2.3 function of the vacuole
stores cell sap
used for storage
helps support the shape of the cell
2.4 how many structures does a plant cell have
8
2.4 how many structures does an animal cell have
5
2.4 in addition to the structures an animal cell has, a plant cell also has
chloroplasts, a (cellulose) cell wall and a vacuole
2.4 what does an animal cell have
a nucleus, cell membrane, mitochondria, ribosomes and a cytoplasm
2.4 what does a plant cell have
a nucleus, cell membrane, mitochondria, ribosomes, cytoplasm, chloroplasts, cell wall and a vacuole
2.7 the chemical elements present in carbohydrates
carbon, hydrogen and oxygen
(C,H,O)
2.7 the chemical elements present in proteins
carbon, hydrogen, oxygen and nitrogen
(C,H,O,N)
2.7 the chemical elements present in lipids (fats&oils)
carbon, hydrogen and oxygen
(C,H,O)
2.8 starch and glycogen is from
simple sugars
2.8 protein is from
amino acids
2.8 lipids are from
fatty acids and glycerol
2.8 a monosaccharide is a …
simple sugar like glucose
2.8 a disaccharide is made when
two monosaccharides join together e.g. maltose = glucose & glucose
sucrose = glucose & fructose
2.8 a polysaccharide is formed when
lots of monosaccharides join together
2.8 polysaccharides starch, glycogen or cellulose are all formed when
lots of glucose molecules join together
2.8 most fats (lipids) in the body are made up of
triglycerides
2.8 lipids basic unit is
one glycerol molecule chemically bonded to three fatty acid chains
2.8 proteins are formed from
long chains of amino acids
2.8 when amino acids are joined together
a protein is formed
2.10 enzymes are biological
catalysts
2.10 a catalyst is a ……..
chemical which increases the rate of a reaction without being used up itself in the reaction
2.10 the theory for understanding how enzymes work is the
lock and key theory
2.10 what is the lock and key theory
the substrate and enzyme collide,
the substrate binds to the active site of the enzyme,
(the reaction occurs by an alternative pathway with a lower activation energy)
once the reaction occurs, the products don’t fit - so they are released,
the enzyme is free to catalyse the next reaction
2.10 the active site has a particular shape which is … to the shape of the substrates
complementary
2.10 because the shape of the active site is complementary to that of the substrates, this means
each enzyme can only catalyse one reaction
2.11 as temperature increases the enzyme & substrate have more
kinetic energy
so they move faster and there are more successful collisions
2.11 high temperatures and changes of pH cause the shape
to change
2.11 when the shape changes we say this is
the protein being denatured
2.11 when the active site changes shape it is no longer
complementary to the substrate
2.12 practical: how can enzyme activity be affected by changes in temperature
place spots of iodine into each dip of a spotting tile
add 5cm^3 of starch suspension into a boiling tube w/ a syringe
with a different syringe add 5cm^3 of amylase solution into another tube
fill a beaker w/ water at 20C & place both boiling tubes inside for 5 minutes
pour amylase solution into the starch suspension leaving it in the water bath
take a sample w/ pipette & add a drop to the iodine solution in the spotting tile
record colour change of the solution in the tile
repeat every 30 seconds for 10 minutes
until the iodine solution remains orange indicating the starch is used up
repeat the experiment with the water bath at diff temps between 20C & 60*C
2.13 what is the optimum pH for most enzymes
7
2.13 which enzymes have a lower pH than 7
those produced in acidic conditions e.g. the stomach
- pH 2
2.13 which enzymes have a higher pH than 7
those produced in alkaline conditions e.g. the duodenum - pH 8/9
2.13 what happens if the pH is too high or too low
the bonds that hold the amino acid chain together can be disrupted / destroyed
this changes the shape of the active site
so the substrate can no longer fit into it
this reduces the rate of activity
moving too far away from the pH - the enzyme will denature
2.15 definition of diffusion
the random movement of particles from an area of higher concentration to an area of lower concentration
2.15 definition of osmosis
the net diffusion of free water molecules from an area of high water concentration to an area of low water concentration across a partially permeable membrane
2.15 osmosis in cell:
what is: solution outside cell has same water potential as inside cell - no net movement
isotonic solution
(animal = normal)
(plant = flaccid)
2.15 osmosis in cell:
what is: solution outside cell has higher water potential then inside cell - net movement of free water molecules into cell
hypotonic solution
(animal = lysed)
(plant = turgid)
2.15 osmosis in cell:
what is: solution outside cell has lower water potential then inside cell - net movement of free water molecules out of cell
hypertonic solution
(animal = shrivelled)
(plant = plasmolysed)
2.15 definition of active transport
movement of molecules from an area of low concentration to an area of high concentration using ATP
2.16 the four main factors that affect the rate of movement
surface area to volume ratio, distance, temperature and concentration gradient
2.16 why is a larger surface area a good thing
it quickens the rate at which substances can move across its surface
2.16 example of large surface area
highly folded surface of the small intestine increases its surface area
2.16 why is a shorter distance a good thing
the smaller the distance molecules have to travel, the faster the transport will occur
2.16 example of short diffusion distance
alveoli walls are one cell thick - rate of diffusion across them is as fast as possible
2.16 why is higher temperature a good thing
the higher the temperature, the faster molecules move as they have more energy
2.16 how is higher temp a good thing
because there are more collisions against the cell membrane and therefore a faster rate of movement across them
2.16 why is a greater difference in a concentration gradient a good thing
the greater the difference in concentration on either side of the membrane, the faster movement across it will occur
2.16 how is a greater difference in a concentration gradient a good thing
because the on the side with the higher concentration, more random collisions against the membrane will occur
2.17 practical: investigating diffusion
coloured agar is made from indicators
coloured agar is cut into required dimensions
calculate the surface area, SA:V R and volume and record it
cubes placed in boiling tubes of different solutions (same volume of it)
^^^ e.g. dilute hydrochloric acid
measurements taken of time for cube to completely change colour of indicator
can draw a graph of rate of diffusion (rate of colour change) changes with surface area : volume ratio of agar cubes
2.17 practical: investigating osmosis
prepare a range of sucrose (sugar) solutions ranging from 0 Mol/dm3 (distilled water) to 1 mol/dm3
set up 6 labelled test tubes with 10cm3 of each of the sucrose solutions
using the knife, cork borer and ruler, cut 6 equally-sized cylinders of potato
blot each one with a paper towel and weigh on the balance
put 1 piece into each concentration of sucrose solution
after 4 hours, remove them, blot with paper towels and reweigh them
2.27 function of the mouth
where mechanical digestion takes place
teeth chew food - smaller pieces
amylase enzymes in saliva digest starch into maltose
shaped into bolus so it can be swallowed
2.27 function of the oesophagus
connects mouth to the stomach
contractions take place to push bolus down
2.27 function of the stomach
food’s mechanically digested by churning
protease enzymes chemically digest proteins
hydrochloric acid kills bacteria & optimum pH for protease enzymes to work
2.27 function of the small intestine
(duodenum)
food coming out stomach finishes being ^ - digested by enzymes produced here & also secreted from the pancreas
! slightly alkaline pH 8-9
2.27 function of the large intestine
(colon & rectum)
water is absorbed from remaining material in the COLON to produce faeces
faeces is stored in the rectum and removed through the anus
2.27 function of the pancreas
produces amylase, protease & lipase
secretes enzymes is an alkaline fluid into the duodenum to raise pH of fluid coming out of the stomach
2.27 what are the 6 structures in the alimentary canal
mouth, oesophagus, stomach, small intestine, large intestine & pancreas
2.27 function of the small intestine
(last part of the small intestine- ileum)
where absorption of digested food
- molecules takes place
long & lined with villi - increasing surface
- area where absorption can take place
! slightly alkaline pH 8-9
2.27 the stages of food breakdown
ingestion - taking in substances,
mechanical digestion - breaking food into smaller pieces
chemical digestion - large, insoluble molecules broken down into small, soluble molecules
absorption - movement of small food molecules and ions through the wall of the intestine into the blood
assimilation - movement of digested food molecules into body where they are used, becoming part of the cells
egestion - passing out undigested or unabsorbed food (as faeces) through the anus
2.29 protein ——>
protein —(pepsin)—>
[peptides] —(trypsin)—> amino acids
2.29 (carbohydrates?) starch ——>
(carbohydrates?) starch —(amylase)—> [maltose] —(maltase)—> glucose
2.29 lipids ——>
lipids —(lipase)—> glycerol & fatty acids
2.29 what enzyme breaks down protein into peptides
what enzyme breaks down peptides amino acids
protease: pepsin
pepsin is made in the stomach
protease: trypsin
trypsin is made in the pancreas & small intestine
2.29 what enzyme breaks down carbohydrates into maltose
what enzyme breaks down maltose into glucose
carbohydrase: amylase
amylase is made in pancreas and salivary glands
carbohydrase: maltase
maltase is made in pancreas
2.29 what enzyme breaks down lipids into fatty acids and glycerol
lipase: lipase enzymes
lipase enzymes are produced in the pancreas
2.32 how is the small intestine adapted for absorption
it is very long and has a highly folded surface with millions of villi
which increase the surface area allowing absorption to take place faster and more efficiently
peristalsis helps by mixing food and enzymes and keeping things moving
2.32 how is the structure of a villus adapted for absorption
a large surface area:
microvilli on the surface
short diffusion distance:
one cell thick walls
steep concentration gradient:
- surrounded by a network of blood
capillaries - transport
glucose&amino acids away
- a lacteal to transport fatty acids and glycerol away
2.34 how does the process of respiration produce ATP
energy is released from glucose either in the presence of oxygen (aerobic) or no oxygen (anaerobic)
resulting in the production of carbon dioxide and water as waste products
energy is transferred in the form of ATP
2.35 what does ATP provide for cells
ATP provides energy for cells
(muscle contractions & keeping warm - painting a constant temperature)
2.36 differences between aerobic & anaerobic respiration
aerobic needs oxygen
anaerobic doesn’t need oxygen
2.36 differences between aerobic & anaerobic respiration with the breakdown of glucose
breakdown is complete in aerobic
breakdown is incomplete in anaerobic
2.36 differences between aerobic & anaerobic respiration with the products
aerobic = carbon dioxide & water
In anaerobic:
animal cells= lactic acid
yeast= carbon dioxide & ethanol
2.36 differences between aerobic & anaerobic respiration with the energy released
aerobic releases a lot of energy
anaerobic releases a little
2.37 word equation for aerobic respiration
glucose + oxygen → carbon dioxide + water
2.37 the balanced chemical symbol equation for aerobic respiration
C6H12O6 + 6O2 → 6CO2 + 6H20
2.38 the word equation for anaerobic respiration in animals
glucose —> lactic acid
2.38 the word equation for anaerobic respiration in plants
glucose —> ethanol + carbon dioxide
2.39 practical: evolution of carbon dioxide from respiring seeds
measure out 10 cm3 of hydrogencarbonate indicator into 3 boiling tubes
put in a layer of cotton wool
place 10 germinating seeds in tube A
place 10 boiled/dead seeds in tube B
place 10 glass beads in tubeC
seal each tube with a rubber bung
after 3 hours, observe the colour of the indicator
high CO2 = yellow
atmospheric CO2 = orange
low CO2 = purple
2.39 practical: demonstrating the production of heat from respiring seeds
flask A with the dead seeds
flask B with the germinating seeds
make sure the cotton wool is plugging the top of each flask
hold the thermometer in place with the cotton wool
invert the flask
record the initial temperature
after 4 days, record the final temperature
2.39 practical: CORMS evaluation evolution of carbon dioxide
change - we will change the content of the boiling tube (germinating seeds, dead seeds or glass beads)
organisms - the seeds used should all be of the same age, size and species
repeat - we will repeat the investigation several times to ensure our results are reliable
measurement 1 - we will observe the change in the hydrogen carbonate indicator
measurement 2 - …after 3 hours
same - we will control the volume of hydrogen carbonate indicator, the number of seeds/beads, the temperature of the environment
2.39 practical: CORMS evaluation evolution of heat
change - we will change the content of the flasks (germinating seeds or dead seeds)
organisms - the seeds used should all be of the same age, size and species
repeat - repeat the investigation several times to ensure our results are reliable
measurement 1 - change in the temperature on the thermometer
measurement 2 - …after 4 days
same - control the number of seeds, the starting temperature of the flasks, the material and size of the flasks
2.39 practical: analysis
the thermometer in the flask with the germinating seeds (Flask B) should show an increase in temperature
- the seeds in flask B are respiring and producing heat energy in the process
flask A should remain at room temperature
the seeds in flask A are not respiring because they are dead, so the temperature remains the same
this shows that respiration is an exothermic reaction
2.49 smoking can cause … and several types of cancer including …
coronary heart disease and lung cancer
2.49 what does nicotine do
it narrows blood vessels - increased blood pressure
increased heart rate
2.49 what does carbon monoxide do
binds irreversibly to haemoglobin
breathing frequency has to increase
increases risk of coronary heart disease & strokes
2.49 emphysema does what
makes the alveoli less elastic & cannot stretch
the breakdown of alveoli reduces the surface area for gas exchange
2.49 smoking increases the risk of cancer which is
the rapid uncontrolled cell growth
2.49 tobacco smoke contains ______ ________ which permanently binds to the haemoglobin forming __________________ reducing the amount of oxygen being transported by the blood
carbon monoxide
carboxyhaemoglobin
2.49 in healthy lungs the linings of the trachea and bronchi are
specialised to prevent dirt and bacteria entering the lungs
2.49 the cilia of the lining cells move transporting the mucus
up the airways where it is then swallowed
2.49 chemicals in tobacco smoke destroy _____ reducing their number, at the same time mucus production will increase. the mucus cannot be moved out of the airways quickly so it ______ __ causing _______ _____ and increases the risk of infection
cilia
builds up
smokers cough
2.49 __________ is a disease resulting from the build up of in refuted mucus in the bronchi and bronchioles
bronchitis
2.49 smoke can also reach the alveoli damaging them: the alveoli walls break down in places and fuse together forming larger irregular air spaces this ___ the surface area for gas exchange so ____ oxygen diffuses into the blood, this disease is called _________ and kills around 20k people in Britain per year
decreases
less
emphysema
2.49 chemicals in cigarettes include:
tar - a carcinogen (a substance that causes cancer)
nicotine - an addictive substance which also narrows blood vessels
carbon monoxide - reduces the oxygen-carrying capacity of the blood
2.50 practical: the effect of excerise on breathing method
work out student A’s breathing rate at rest
count their number breaths for 15 seconds and multiply by 4
repeat to calculate an average
student A should then exercise for a set time (at least 4 minutes)
count the breaths taken in 15 seconds and multiply by 4 to obtain the breathing rate per minute
compare the result to the breathing rate at rest in order to work out the change in breathing rate as a result of exercise
repeat this last step every minute after exercise for 5 minutes
repeat the process for student B
finally, repeat the whole investigation for each student after a period of rest
2.50 practical: the effect of exercise on breathing results
frequency of breathing increases when exercising
this is because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with the energy demand
if they cannot meet the energy demand they will also respire anaerobically, producing lactic acid
2.50 practical: the effect of exercise on breathing analysis
after exercise has finished, the breathing rate remained elevated for a period of time
this is because the lactic acid that has built up in muscles needs to be removed as it lowers the pH of cells and can denature enzymes catalysing cell reactions
it can only be removed by combining it with oxygen - this is known as ‘repaying the oxygen debt’
this can be tested by seeing how long it takes after exercise for the breathing rate to return to normal
the longer it takes, the more lactic acid produced during exercise and the greater the oxygen debt that needs to be repaid
2.50 practical: what might an unfit individual have
higher breathing rate while resting
more rapid increase in breathing rate during exercise
longer recovery period for their breathing rate to return back to a normal resting rate
2.50 practical: how do you control all variables
ensure students are similar size, general fitness, age, gender and provide each with the same meal before exercise
2.50 practical: CORMS evaluation
change - We will change whether the student has exercised or not
organisms - The students should be of the same age, gender, size and general fitness
repeat - We will repeat the investigation several times to ensure our results are reliable
measurement 1 - We will measure the change in breathing rate
measurement 2 - …immediately after exercise and each minute for the subsequent 5 minutes
same - We will control the type of exercise carried out, the temperature of the environment, the food intake of the students prior to the investigation
2.50 practical: exercise causes the frequency
exercise causes the frequency of breathing to increase in order to provide more oxygen for respiration and to pay off any subsequent oxygen debt
2.50 practical: apparatus needed for the effect of exercise
a stop watch
2 students
2.56B the loss of water vapour from the leaves is called
transpiration
2.56B examiners definition of transpiration
the evaporation of water from the surface of a plant
2.57B how does temperature affect the rate of transpiration
water will evaporate quickly as the water molecules have more kinetic energy
2.57B how does humidity affect the rate of transpiration
humid air - water vapour = smaller conc gradient so transpiration slows down
2.57B how does wind speed affect the rate of transpiration
moving air - water vapour blown away from leaf - speeds up transpiration
2.57B transpiration .. as wind speed ..
transpiration increases as wind speed increases
2.57B transpiration .. as humidity ..
transpiration increases as humidity decreases
2.57B transpiration .. as temperature ..
transpiration increase as temp increases
2.57B light intensity does NOT affect
evaporation
2.57B how does light intensity affect the rate of transpiration
in daylight stomata leaves are open to supply CO2 for photosynthesis
allows more water to diffuse out leaves into atmosphere
2.58B practical: how to set up a potometer
set up underwater
cut the stem
shoot stem in bung
grease joint w jelly (no air entry/water loss)
bung in potometer
tap closed full of water
lift potometer out of water
leave end of capillary tube out of water until air bubble forms & then put in beaker of water
measure rate as distance bubble travelled in 5 mins
2.58B practical: a potometer is to measure
measure the rate of water uptake from a leafy shoot
2.58B practical: we can use potometer to collect readings in normal air or windy conditions by
using a hairdryer on cold
2.58B practical: we can use potometer to collect readings in temperature
increases and decreases
2.58B practical: we can use potometer to collect readings in increased humidity by
using a clear plastic bag
2.58B practical: we can use potometer to collect readings by changing the l & d
lightness and darkness
2.58B practical: changing the environmental factors stimulates
all the different conditions which affect the rate of transpiration
2.1 organelle ->
c , t , o , o & o
cell, tissue, organ, organ system & organism
2.1 organelles are
structures that carry out specific processes the cell needs to survive
2.1 tissues are
groups of similar cells
that work together to carry out the same function
2.1 an example of tissue in humans is
muscle tissue
2.1 organs are made up of
several different tissues
working together to carry out a more complex function
2.1 an example of an organ in a human is
the heart
(muscle is one of the tissues making up the heart)
2.1 organ systems are made up of
several different organs working together to carry out a complex function essential to life
e.g. circulating blood around the body
2.1 organelle ->
cell
2.1 cell ->
tissue
2.1 tissue ->
organ
2.1 organ ->
organ system
2.1 organ system ->
organism
2.46 what is the thorax
the human chest cavity
2.46 what does the thorax consist of
the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes
2.46 in the thorax describe the structure of the ribs
bone structure that protects internal organs such as the lungs
2.46 in the thorax describe the structure of the intercostal muscles
muscles between the ribs which control their movement causing inhalation & exhalation
2.46 in the thorax describe the structure of the diaphragm
sheet of connective tissue and muscle at the bottom of the thorax that helps change the volume of the thorax to allow inhalation & exhalation
2.46 in the thorax describe the structure of the trachea
windpipe that connects the mouth and nose to the lungs
2.46 in the thorax describe the structure of the larynx
also known as the voice box, when air passes across here we are able to make sounds
2.46 in the thorax describe the structure of the bronchi (plural)
large tubes branching off the trachea with one bronchus (singular) for each lung
2.46 in the thorax describe the structure of the bronchioles
bronchi split to form smaller tubes called bronchioles in the lungs connected to alveoli
2.46 in the thorax describe the structure of the alveoli
tiny air sacs where gas exchange take place
2.46 in the thorax describe the structure of the pleural cavity
the fluid filled space between the pleural membranes which reduces friction and allows the lungs to move freely
2.46 the lungs are the … surface in humans
gas exchange
2.46 what features do all gas exchange surfaces have in common
large surface area for faster diffusion of gases across the surface
thin walls to ensure diffusion distances remain short
good ventilation with air so diffusion gradients can be maintained
good blood supply to maintain a high concentration gradient so diffusion occurs faster
2.47 muscles are only able to pull on bones not push them meaning
there must be two sets of intercostal muscles to work antagonistically to facilitate breathing
2.47 what do the external intercostal muscles do
pull the ribcage up
2.47 what do the internal intercostal muscles do
pull the ribcage down
2.47 which intercostal muscles pull the ribcage up
the external intercostal muscles
2.47 which intercostal muscles pull the ribcage down
the internal intercostal muscles
2.47 what is the diaphragm
a thin sheet of muscle that separates the chest cavity from the abdomen
2.47 during inhalation describe the diaphragm & intercostal muscles
external intercostal muscles contract
ribcage moves up and out
diaphragm contracts & flattens
volume of thorax increases
pressure inside thorax decreases
- relative to the outside body -
air is drawn in
2.47 during exhalation describe the diaphragm & intercostal muscles
external intercostal muscles relax
ribcage moves down and in
diaphragm relaxes & becomes dome-shaped
volume of thorax decreases
pressure inside thorax increases
- relative to the outside body -
air is forced out
2.48 how are alveoli highly adapted for gas exchange
large surface area to volume ratio:
there are many rounded alveolar sacs
minimise / short diffusion distance:
alveoli have thin, single layers of cells
steep concentration gradient:
ventilation maintains high levels of oxygen & low levels of carbon dioxide
good bloody supply & maintains concentration gradients:
ensures a constant supply of blood high in carbon dioxide & low in oxygen
a layer of moisture on the surface of the alveoli helps diffusion as gases dissolve
2.49 smoking cigarettes has been linked to
disease in the lungs and is a risk factor in coronary heart disease
2.49 what does nicotine in cigarettes do
narrows blood vessels and increases heart rate, leading to increased blood pressure
causes high blood pressure that leads to blood clots forming in the arteries potentially resulting in heart attack or stroke
2.49 what does carbon monoxide in cigarettes do
binds irreversibly to haemoglobin reducing the capacity of blood to carry oxygen
breathing frequency & depth need to increase putting more strain on the breathing system
circulatory system needs to pump blood faster
- raising blood pressure & increasing risk of coronary heart disease & stroke
2.49 what does tar in cigarettes do
it’s a carcinogen linked to increased chances of cancerous cells developing in the lungs
contributes to COPD which occurs when chronic bronchitis and emphysema occur together
2.49 what happens in chronic bronchitis
tar stimulates goblet cells & mucus glands to enlarge and produce more mucus
mucus builds up blocking the smallest bronchioles
leading to infections
build up of mucus can result in damage to the cilia preventing them from beating & removing the mucus
a smokers cough is the attempt to move the mucus
2.49 what happens in emphysema
phagocytes that enter the lungs release elastase an enzyme that breaks down the elastic fibres in the alveoli
alveoli become less elastic & cannot stretch so many burst
the breakdown of alveoli reduces the surface area for gas exchange
patients become breathless & wheezy
2.67 what are the factors that may increase the risk of developing coronary heart disease?
- Obesity
- High Blood pressure
- High Cholestrol
- Smoking
2.67 how can obesity increase risk of developing coronary heart disease?
Carrying extra weight puts a strain on the heart.
increased weight can lead to Type 2 diabetes which further damages the blood vessels.
2.67 How can high blood pressure increase risk of developing coronary heart disease?
High blood pressure increases the force of the blood against the artery walls and consequently leads to damage of the vessels.
2.67 How can high cholestrol increase risk of developing coronary heart disease?
High cholestrol speeds up the build up of fatty plaques in the arteries which leads to blockages.
2.67 How can smoking increase risk of developing coronary heart disease?
Chemicals in smoke cause an increase in plaque build up and and increase in blood pressure.
Carbon monoxide also reduces the oxygen carrying capacity of the red blood cells.
2.68 How many types of blood vessel are there? And name them
3.
Arteries, veins, capillaries.
Each vessel is specifically adapted to carry out its particular function efficiently.
2.68 What are the smaller vessels that branch off from the arteries called?
Arterioles (small arteries)
2.68 What are the smaller vessels that branch into veins called ?
Venules (small veins)
2.68 What are the key features of arteries?
Carry blood at high pressure away from the heart
Carry oxygenated blood (except pulmonary artery)
Have thick muscular walls containing elastic fibres
Have a narrow lumen
Blood flows through at a fast speed.
2.68 How is the structure of an artery adapted to its function?
Thick muscular walls containing elastic fibres withstand the high pressure of blood and maintain the blood pressure as it recoils after the blood has passed through
A narrow lumen also helps to maintain high pressure.
See images
2.68 What are the key features of veins?
Carry blood at low pressure towards the heart
Carry deoxygenated blood (other than the pulmonary vein)
Have thin walls
Have a large lumen
Contain valves
Blood flows through a slow speed
2.68 How is the structure of a vein adapted to its function?
A large lumen reduces resistance to blood flow under low pressure.
Valves prevent the backflow of blood as it is under low pressure
2.68 What are the key features of capillaries?
Carry blood at low pressure within tissues
Carry both oxygenated and deoxygenated blood
Have walls that are one cell thick
Have ‘leaky’ walls
Speed of blood flow is slow
2.68 How is the structure of a capillary adapted to its function?
Capillaries have walls that are one cell thick (short diffusion distance) so substances can easily diffuse in and out of them.
The ‘leaky’ walls allow blood plasma to leak out and form tissue fluid surrounding cells.
