Key Unti 3 Revision Flashcards
How are alveoli specialised for their purpose
A large surface area
A moist lining for dissolved gases
Very thin walls so short path for diffusion
A good blood supply.
How do white blood cells defend against disease
They can change shape to consume microorganisms
They produce antibodies to fight microorganisms as well as antitoxins to neutralise any toxins produced by microorganisms
What is carried in plasma
Red blood cells White blood cells Platelets Nutrients like glucose and amino acids soluble products of digestion Carbon dioxide Urea Hormones Antibodies antitoxins
Pathway of oxygen into lungs
The air that you breath in goes through the trachea.
This splits into two tubes called bronchi, each on is called a bronchus, one going to each lung.
The bronchi split into progressively smaller tubes called bronchioles finally ending at the alveoli, where the gas exchange takes place.
Breathing in and out
When you breath in.
Your intercostal muscles contract, pulling your ribs upwards and outwards. At the same time your diaphragm muscles contract.
This flattens your diaphragm from its normal, domed shape. These two movements increase the volume of the thorax. Because the same amount of gas is now inside a much bigger space, the pressure inside your thorax decreases, pressure inside the thorax is now lower than the pressure of the air outside your body. As a result air moves into your lungs.
When the intercostal muscles relax your ribs drop down and inwards again. When the diaphragm relaxes it curves back up into your thorax. As a result the volume of your thorax gets smaller again. This increases the pressure inside the chest so the air is squeezed and forced out of the lungs, that’s how you breath out.
How do we control body temperature and why
If you get too hot, your enzymes denature and can no longer catalyse the reactions in your cells. When your core body temperature begins to rise impulses are sent from the thermoregulatory centre to the body so more energy is released.
The blood vessels supplying your skin capillaries dilate, this lets more blood flow through the capillaries. Your skin flushes so you lose more energy by radiation.
Your rate of seating goes up, this extra sweat cools you down as it evaporates. In humid weather when the sweat does not evaporate it is much harder to keep cool.
If you get too cold the rate of enzyme controlled reactions in your cells falls too low. You don’t release enough energy and your cells begin to die. If your core body temperature starts to fall, impulses are sent from your thermoregulatory centre to the body to conserve and even release more energy.
The blood vessels that supply your skin capillaries constrict to reduce the flow of blood through the capillaries, this reduces this reduces the energy released by radiation through the surface of the skin.
You sweat less, less sweat evaporates so less energy is released.
You shiver, your muscles contract and relax rapidly these muscle contractions need respiration which release more energy this raises your body temperature.
Why must the body maintain a constant temperature.
To maintain the optimum functioning of the enzymes in the body.
Responses to hot and cold
Hot.
Body temperature rises Thermoregulatory centre Body responses triggered Hairs lie flat Lots of sweat produced Blood vessels supplying the capillaries near the surface of the skin dilate so blood flowing through them increases and more energy is lost to the environment.
Body temperature falls
Body temperature falls Thermoregulatory centre Body responses triggered No sweat Hairs pulled erect to trap insulating layer of air
Blood vessels supplying capillaries near the surface of the skin constrict so the blood flowing through the capillaries decreases less energy is released to the environment.
Body temperature rises
Why are the levels of glucose in your blood important
It’s important that your cells have a constant supply of the glucose they need for respiration
What is the process of eutrophication
Fertilisers are added to the soil. The minerals in these fertilisers particularly the nitrates are
Easily washed from the soil into local streams and ponds and rivers.
Untreated sewage that is washed into the waterways or pumped out into the sea also cause high levels of nitrates in the water.
The nitrates and other minerals fertilise the water plants which then rapidly some plants die naturally. Others die because there is so much competition for light. There is a big increase in microorganisms feeding on the dead plants. These microorganisms use up a lot of oxygen. This increase in decomposers leads to a fall in oxygen levels dissolved in the water.
This means there isn’t enough oxygen to support some of the fish and other animals living in it. They die- and are decomposed by more microorganisms this uses up even more oxygen.
Eventually the oxygen levels in the water fall so low that all aquatic animals die and the pond or stream becomes ‘dead’ this is called eutrophication
What are bioindicators
Species which can only be found in very clean or polluted water.
Name three fossil fuels
Oil, coal and natural gas
Name three none renewable resources used for fuel.
Oil, coal and natural gas
How does Acid rain effect the environment.
It falls onto the trees it may kill the leaves and as it soaks into the soil it can destroy the roots as well. Whole ecosystems can be destroyed.
As acid rain falls into lakes rivers and streams the water in them becomes acidic. If the concentration of acid gets too high plants and animals can no longer survive.
Many lakes and streams have become ‘dead’ no longer able to support life.
Formation of acid rain.
When fossil fuels are burnt carbon dioxide is released into the atmosphere as a waste product. In addition fossil fuels often contain sulfur impurities. These react with oxygen when they burn to form sulfur dioxide gas. At high temperatures eg in car engines nitrogen oxides are are also released into the atmosphere.
Sulfur dioxide and nitrogen oxides can cause serious breathing problems for people if the levels get to high
The sulfur dioxide and nitrogen oxides dissolve into rain water and react with oxygen in the air to for, dilute sulfuric acid and nitric acid. This produces acid.
This is often caused by pollution from factories and cars.
