Topic 3 - Organ Systems Flashcards
What evidence is there for evolution?
Fossils
Pentadactyl limb
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 platelets nutrients such as glucose and amino acids carbon dioxide urea hormones antibodies and antitoxins
What are the three blood vessels?
artery
veins
capillaries
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.
