B2.2 Flashcards
What substances are needed by ( diffuse into ) the organism
Mineral ions, O2, H2O, glucose, amino acids
What substances need to be removed ( diffuse out ) of the organism
CO2, Urea ( liver cells )
SA:V formula
Surface area divided by volume
What happens to the surface area to volume ratio as the size of the cube increases
The bigger the volume is the surface area is smaller
What happens to the diffusion distance as the size of the cube increases
It increases
Why does a tapeworm need a big surface area to volume ratio
Nutrients diffuse directly into the organism quickly enough to sustain life as diffusion distances are short.
What affects the amount of each material that needs to be exchanged
Metabloic rate
What do lungs have to increase surface area
Alveoli
What does a small intestine have to increase surface area
Finger like villi and microvilli
What is your heart made of
Cardiac muscle
Which side of the heart has a thicker muscular wall
Left
What is the function of heart valves
The valves seperate the chambers and importantly prevent the back flow of blood
Where does the pulmonary things go to
The lungs
How much does a heart beat per min
70
Why is it bigger on the left
It allows it to contract with more force and generate a greater blood pressure as it is going all around the body instead of just the lungs
What type of system is the circulatory sytem
A closed system
What does blood transport around the body
Glucose and oxygen needed for respiration
What is the hollow cavity in the centre called
Lumen
Which way does a vein and arterie carry blood
Vein = towards the heart Arterie = away from the heart
Why are arteries walls thick
They are thick and muscular so that they can expand and then snap back to push blood forward ( because of very high blood pressure caused by the heart contracting )
Blood pressure in order
Arterie
Vein
Capillaries = drops blodd pressure/ slows it down
Wall thickness in order
Artery
Vein
Capillaries
How thick are capillaries and y
One cell thick
Semi permeable
So substances can move through them easily
What do veins have that the others dont
Valves
Why do capillaries form a network
So that every cell is close to one of these blood vessels
What is a double circulatory system
When the blood passes through the heart twice on every circuit of the body
What is the advantage of having a double circulatory system
Higher blood pressure
