SB8 Flashcards
What do our lungs get rid of
Carbon dioxide produced in aerobic respiration
Why is a lung’s surface area so large
It’s packed with alveoli that increases surface area and thus speed of gas exchange
Why is there a limit to a cell size
Because the SA:V ratio would be too small and the cell wouldn’t be able to get raw materials fast enough
What does the alveoli do
Where gases diffuse in and out of the bloodstream (oxygen into the bloodstream and carbon dioxide out)
Name the adaptations of alveoli
Very thin walls so the diffusion path is short (one cell thick)
A lot of blood vessels around them (capillaries)
A lot of them, large surface area
What is Fick’s law
Rate of diffusion ∝ (surface area x concentration difference) ÷
thickness of membrane
What do veins do and what do they have
Carry deoxygenated blood to the heart
Wide
Thin, flexible wall
What do arteries do and what do they have
Take oxygenated blood away from the heart to the rest of the body
Narrow
Thick layer of elastic and muscle fibres
What are capillaries and what do they have
Connect the arteries and veins
One cell thick wall (allows for diffusion quicker)
Narrow
What is a pulse
A shock wave that travels through the walls of the arteries each time the heart pumps
What do valves do
They prevent blood flowing the wrong way
Why do veins have thin walls
Because blood flows under low pressure in the veins
What cells are in the blood
Red blood cells (erythocytes)
White blood cells
Platelets
Plasma
What does haemoglobin do
Binds to oxygen in the lungs and releases it again in tissues
Why do red blood cells have a biconcave shape with no nucleus
Allows for a larger surface area for oxygen to diffuse in and out
What do lymphocytes do
Produce antibodies that identify and kill foreign cells
What do phagocytes do
Surrounds and engulfs foreign cells
What causes a heart attack
Blood stopping flow to the heart
What are the four chambers in the heart
The left atrium (at the top)
The right atrium (at the top)
The left ventricle
The right ventricle
What does the vena cava do
It brings deoxygenated blood from the body
What does the pulmonary vein do
Passes deoxygenated blood from the heart to the lungs
What does the pulmonary vein do
Passes oxygenated blood from the lungs to the heart
What does the aorta do
Passes oxygenated blood from the heart to the body
How is blood pumped in the heart
Deoxygenated blood flows in through the right atrium into the right ventricle
Oxygenated blood flows through the left atrium into the left ventricle
Ventricles contract, pushing blood out of the heart
The valves in the heart prevent blood from flowing back into the atria
Why does the left side of the heart have thicker walls
It needs to pump a lot of blood around the body and so requires a larger force
What do tendons do
They stop valves from turning inside out
What is heart rate
The amount of times your heart beats per minute
What is the formula for cardiac output
Cardiac output (litres/min) =stroke volume (litres/beat) x heart rate (beats/min)
Why do organisms need to respire
Because cellular respiration provides energy, organisms need energy for movement
Why is respiration exothermic
Because it releases energy
What do platelets do
They form blood clots to stop/prevent bleeding
What do plasma do
They transport carbon dioxide, digested food, urea, hormones and heat
What happens in aerobic respiration
Glucose and oxygen react to form carbon dioxide and water (this happens in the mitochondria)
Why does aerobic respiration release so much energy
Because the glucose has been fully oxidised
Why does anaerobic respiration happen
When there is a shortage of oxygen
What are the formulae for anaerobic respiration
Glucose –> lactic acid (in the cytoplasm)
Glucose –> ethanol + carbon dioxide (in plant and yeast cells)
Why does anaerobic respiration release less oxygen
Because the oxidation of glucose is incomplete
What is fermentation
Anaerobic respiration in yeast cells
Why do breathing and heart rates increase after exercise
To replace extra oxygen lost from blood and muscles and to get rid of lactic acid
What is soda lime used for in the experiment?
Absorbs carbon dioxide so it doesn’t interfere with the coloured liquid
What is cotton wool there for in the experiment?
To protect the organism and you
What is the coloured liquid used for in the experiment?
To see the amount of oxygen used
Compare anaerobic and aerobic respiration
Anaerobic respiration takes place without oxygen
In both reactions, glucose is broken down to release energy
Both produce carbon dioxide
Energy is released in both reactions
Aerobic respiration releases more energy
The glucose in aerobic respiration is fully oxidised
