Flashcards in Topic 3 - Organ Systems Deck (51):
What evidence is there for evolution?
why do fossils provide evidence of evolution?
They are traces of plants and animals that lived long ago.
how are fossils formed?
Minerals replace teeth shells bones etc to form solid rock-like things.
Buried in soft material which leaves an impression when material hardens
preserved in something because conditions prevent microbes from working. e.g glacier, peat bogs, amber.
what do fossils found in rock layers tell us?
what creatures looked like
how long ago they existed
how they've evolved, by studying the differences in different aged rocks we can see the ways they've changed
how does the pentadactyl limb provide evidence for evolution?
it is a limb with five digits.
many species have it
the pentadactyl limb in each species has a similar bone structure.
It shows that we have evolved from a common ancestor.
what is growth?
an increase in size or mass.
Size is something you measure like height, length, width, or circumference.
Wet mass is the mass of of an organism with all the water in its body.
Dry mass is the mass with no water in.
what are tissues??
a group of similar cells that work together to carry out a particular function
What are organs?
A group of different tissues that work together to carry out a particular function
what are organ systems?
a group of organs working together to perform a particular function
what is the journey of blood through the heart?
body - de-oxygenated - vena cava - right atrium - right ventricle - pulmonary artery - lungs - oxygenated - pulmonary vein - left atrium - left ventricle - aorta - body
what do valves do?
prevent the back flow of blood
What do red blood cells do?
they carry oxygen round the body from the lungs
why do red blood cells have a biconcave disc shape?
it gives it a large surface area for absorbing oxygen.
What does the haemoglobin do?
it contains iron.
In the lungs it combines with oxygen to become oxyhemoglobin and in body tissues the reverse happens to release oxygen to the cells.
What does a lack of iron cause?
anaemia which is when the body can't carry enough oxygen
how do white blood cells defend against disease?
They change shape to destroy unwelcome microorganisms.
Produce antibodies to fight microorganisms
produce antitoxins to neutralise toxins
What does a low white blood cell count result in?
increased risk of infection
what does a high white blood cell count mean?
you have an infection or leukaemia
What are platelets and what do they do?
they are small fragments of cells.
They help the blood clot at a wound to stop blood pouring our and microorganisms getting in.
Lack of platelets can result in excessive bleeding and bruising.
what is plasma
pale yellow liquid that keeps the blood fluid and transports things.
What does the plasma transport
red blood cells
white blood cells
nutrients such as glucose and amino acids
antibodies and antitoxins
What are the three blood vessels?
what is the function and characteristics arteries?
carry blood away from the heart.
they pump blood out at high pressure so the artery walls are strong and elastic.
the walls are thick compared to the size of the lumen (hole in the middle) they contain thick layers of muscle to make them strong.
branch into capillaries.
What is the function and characteristics of veins?
Carry blood to the heart.
Blood is at a low pressure in the veins so the walls don't need to be as thick as arteries.
Bigger lumen than arteries to help the blood flow.
Have valves to help blood flow the right way.
What is the function and characteristics capillaries?
involved in the exchange of materials with the tissues.
really small, too small to see.
Carry blood close to each cell in the body to exchange substances with them.
Permeable walls so diffusion can happen. supply food and oxygen and take away waste like co2.
Walls only one cell thick which increases the rate of diffusion whilst decreasing the distance over which it occurs.
join up to form veins.
which molecules are too big to pass through the walls of the digestive system?
starch proteins and fats
Which molecules are small enough to pass through the walls of the digestive system?
sugars, amino acids, glycerol, fatty acids
Which enzymes breaks down starch
carbohydrases (amylase) digests starch into sugars
which enzymes break down protein?
proteases (pepsin) protein -> amino acids
which enzymes breaks down fat?
fat -> fatty acids and glycerol.
what organs are involved in digestion
small & large intestine
function of mouth in digestion
food is moistened with saliva which contains amylase so breaks down starch.
Food is chewed and broken into smaller pieces to form a bolus before being swallowed.
function of oesophagus in digestion
tube that takes food from the mouth to the stomach. Lined with muscles that contract to help the bolus move by peristalsis.
Function of stomach in digestion
pummels food with muscular walls
produces protease enzymes pepsin
produces HCl to kill bacteria and give the right pH for protease
Function of liver in digestion
Where bile is produced, it neutralises stomach acid and emulsifies fats
function of gall bladder in digestion
bile stored before released into small intestine
function of pancreas in digestion
produces protease, amylase, and lipase enzymes into the small intestine
Function of small intestine in digestion
produces protease, amylase, and lipase to complete digestion.
food absorbed out of digestive system into body
function of large intestine in digestion
excess water absorbed from food
What can you use to model the gut
Why is visking tubing a good model
it only lets small molecules through
cheaper and easier than using animals gut
Why is visking tubing a bad model
guts a lot longer and has a massive surface area so the speed of digestion will be different
What can be used to test for starch
iodine turns from orange/brown to blue/black if starch is present
What can be used to test for sugars
blue - green - yellow- orange - brick red
How does enzyme concentration affect the rate of reaction
the higher the concentration the faster the rate of reaction up to a point.
What is peristalsis
waves of circular muscle contractions push food
waves of longitudinal muscle contractions keep it as a bolus
What are the features of villi that make absorption really efficient
Big surface area so that digested food is absorbed much more quickly into the blood
Single layer of surface cells so that digested food diffuses quickly over a short distance
Good blood supply via capillary network to assist quick absorption of digested food
What are functional foods
Food that has a health benefit beyond basic nutrition
What are probiotics
contain good bacteria that are thought to help keep your digestive system healthy and immune system strong
e.g bifidobacteria, lactobacillus
found in yoghurts and soya milk
What are prebiotics
promote growth of good bacteria which can improve health of digestive system and strengthen immune system