B3 Life processes Flashcards
What is ventilation and explain how it happens.
It is breathing in and breathing out.
When breathing in:
Intercostal muscles and the diaphragm contract(flattens). This lifts the ribs upwards and outwards.
The thorax’s volume gets bigger and air is drawn in as pressure decreases.
When breathing out it is opposite.
Explain the lungs
They are in the thorax.
The diaphragm is under it and separates it from the rest of the body(abdomen)
Protected by the ribcage.
The air that you breath goes through the trachea, which later splits into two bronchi.
The bronchi then split into progressively smaller tubes called bronchioles.
These end in small bags called alveoli where gas exchange happens.
What are ventilators and how do they work?
They move air into and out of the lungs. People who can’t breath by themselves (under general anaesthetic, have a injury or disease) use them.
The iron lung was once used (it could cause problems with blood flow) but now they pump air into the lungs which expand the rib age and when they stop, the ribcage relaxes and pushes the air out again.
This doesn’t interfere with blood flow but could cause burst alveoli.
How does the structure of a leaf allow gas to diffuse in and out of the cells.
Under the leaf is an exchange surface which has many stomata which are small holes which co2 diffuses through.
Oxygen and water vapour are also lost through the stomata (though some water is lost from all the leaf).
Guard cells controls the size of the stomata. They close them if the plant needs to preserve water.
The flat shape of the leaf means there is a large surface area.
The walls of the cells inside the leaf also increase the surface area.
How does gas exchange happen in the lungs?
The lungs have millions of small sacs where gas exchange takes place. These are called alveoli.
They have a massive surface area.
Very thin walls.
A good blood supply.
A moist lining for dissolving gases.
This all means the diffusion of co2 and oxygen is maximised.
What are the villi and what do they do?
They are small projections all over the surface of the small intestine.
They increase the surface area and a very good blood supply meaning digested food can be absorbed by the blood.
They also have single layer of surface cells.
What do phloem do?
They transport food.
They are columns of living cells with small holes in the ends to allow food to flow through.
Food like sugar is made in the leaves and transported to growing and storage regions like shoots and tubers. Transport foes both ways.
What so xylem do?
They are made of dead cells joined end to end with no walls between them. They carry water and minerals from the roots to the stem and leaves in the transpiration steream.
What is the transpiration steam?
Water transpires through stomata meaning the leaf doesn’t have enough water so xylem bring more up from the roots.
In the lungs and body tissue, how does oxygen transfer from the blood?
In the lungs, haemoglobin (found in the red blood cells) combines with oxygen to become oxyhemoglobin. In body tissue the reverse happens, oxyhemoglobin splits up into haemoglobin and oxygen to release it to the cells.
Define osmosis.
It is a special type of diffusion. It is the movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of low water concentration.
What is a partially permeable membrane?
It has very small holes in it. Only very small molecules (like water ) can get through. Bigger molecules can’t (like sucrose)
Explain how osmosis works.
Water molecules will pass both ways through a partially permeable membrane. This is because the molecules always move randomly.
However the net movement of water will be from an area of high concentration to an area of low concentration. It will try to even out the water concentration on each side.
How does osmosis cause water to move in and out of animal cells?
Tissue fluid surrounds the cells in the body. This is water with oxygen, glucose and other stuff dissolved in it. It comes from the blood capillaries.
This fluid will usually have a different concentration to the fluid in the cells.
If a cell is short of water, it will become concentrated on the inside and the solution will be more dilute. Water will move in.
If the cell has lots of water, the inside will be more dilute and water will be draw out.
What do life processes need and how does this happen?
They need gases or other dissolved substances to happen.
E.g. Co2 and water is needed for photosynthesis and for respiration glucose and oxygen is needed.
Waste substances also have to be removed from cells.
Diffusion, osmosis and active transport move theses substances in and out of cells.
How does diffusion work?
It is when particles move from an area of high concentration to an area of low concentration.
The substances will move through an exchange surface.
How are exchange surfaces adapted to maximise the movement of stuff?
They are thin so substances have a short distance to travel.
They have a large surface area do lots of substance can dissolve at once.
In animals, exchange surfaces have lots of blood vessels to get stuff to the blood.
Gas exchange surfaces in animals are often ventilated so more air can move.
How are root hairs specialised for absorbing water and minerals?
The cells on the surface of plant roots grow into long hairs which stick into the soil.
This increases the surface area meaning more water and minerals can get into the plant. This is the main way in which water and minerals can get into the body.
Why don’t root hairs use diffusion to move stuff into them?
The concentration of minerals is usually higher in the cells than in the ground. If diffusion happened, the roots hairs would lose minerals.
They use active transport instead.
What is active transport?
It allows materials to move from an area of low concentration to an area of high concentration. It goes against the concentration gradient. Energy is used in the process. It it used in root hairs and in the gut to get glucose.
What is the double circulatory system in the body?
Two circuits of blood are joined together.
The first one takes deoxygenated blood to lungs to get oxygen and back to the heart. This is pulmonary circulation.
The second pumps oxygenated blood around the body. It will return to the heart deoxygenated. The systematic circulation.
What do vales in the heart do?
Stop blood from flowing in the wrong direction.
What are the four chambers of the heart?
Left and right atrium and left and right ventricle. The atriums are on top of the ventricles.
What is the order of blood going through the heart?
Deoxygenated blood flows in through the wean cave and oxygenated blood through the pulmonary vein into two atria.
The atria contract, pushing blood into the ventricles.
The ventricles contract forcing Deoxygenated blood into the pulmonary artery and oxygenated blood into the aorta. The blood flows to the organs through arteries and returns through veins.
What are the three types of blood vessels and what do they do?
Arteries carry blood away from the heart.
Capillaries are involved in the exchange of materials at the tissues.
Veins. These carry blood to the heart.
Describe arteries.
The blood that goes through is at high pressure so the walls are strong and elastic.
They contain thick layers of muscle to make them strong and elastic fibres to allow them to stretch and spring back.
The walls are thick compared to the lumen.
Describe capillaries.
They branch off from arteries.
Carry blood really close to every cell to exchange substances.
Permeable walls one cell thick to allow diffusion.
They supply oxygen and food, and remove CO2
Define lumen.
The hole down the middle of a blood vessel.
Describe veins.
Capillaries will join up to them.
The blood is at a lower pressure so the walls are less thick.
They have a bigger lumen to allow more blood to flow.
They have valves that keep the blood flowing in the right direction.
What do white blood cells do?
They change shape to ingest microorganisms.
They produce antibodies to fight microorganisms as well as antitoxins.
They do have a nucleus.
What do platelets do?
They are small fragments of cells with no nucleus.
They help blood to clot to stop blood getting out and microorganisms from getting in.
They help produce networks of protein threads which capture red blood cells and the platelets form jelly like clots.
A lack of platelets can cause excessive bleeding and bruising.
What is plasma?
This carries everything within the blood. Red and white blood cells. Platelets. CO2 from the organs to the lungs. Urea from the liver to the kidneys. Hormones. Antibodies and antitoxins produced by the white blood cells. Nutrients like glucose and amino acids.
