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B4: Organising animals and plants - Coggle Diagram
B4: Organising animals and plants
Circulatory system
The heart
The circulatory system is made up of the heart, blood and blood vessels. Humans have a double circulatory system. In the first one the right ventricle pumps deoxygenated blood to the lungs. In the second one, the left ventricle pumps oxygenated blood around the other organs. The blood gives them oxygen and returns.
The heart is an organ that pumps blood around the body. The walls of the heart are mostly made of muscle tissue. The wall of the left ventricle is thicker than the wall of the right ventricle to develop the pressure needed to force the blood through the arterial system. The blood leaving the right ventricle has lower pressure so it doesn't damage the capilary network for gas exchange at the lungs. The muscle tisse is also supplied with oxygen by the coronary arteries. The heart has valves to make sure that blood flows in the right direction.
Blood flows into the two atria from the vena cava which has deoxygenated blood from the body on the right and pulmonary vein on the left which brings oxygenated blood from the lungs. The atria contract, pushing the blood into the ventricles. The ventricles contract,the right ventricle forces deoxygenated blood to the lungs in the pulmonary artery and the left ventricle pumps oxygenated blood around the body in an artery called the aorta.
Cardiovascular disease
Stents
Coronary heart disease is when the coronary arteries get blocked by layers of fatty material building up. The arteries become narrow so blood flow is restricted and there is a lack of oxygen to the heart muscle. This can cause a heart attack
Stents help the arteries. They are inserted inside to keep them open so blood can flow through. There are risks of complications during surgery such as infection. Patients can also develop a blood clot near the stent. This is called thrombosis
Cardiovascular disease is a term used to describe disease of the heart or blood vessels
Mechanical valves
The valves in the heart can be damages or weakened by heart attacks, infection or old age. The damage may cause the tissue to stiffen or they may become leaky allowing blood to flow in both directions. Replacement valves can come from other humans or mammals- these are biological valves but they do not last as long as mechanical valves. Mechanical valves may cause blood clotting so the patient has to take medicine for the rest of their life.
Artificial heart
If a patients has heart failure then doctors may perform a heart transplant using donor organs. However, if one is not available doctors may use an temporary artificial heart but sometimes they are permanent.
The main advantage is that it is less likely to be rejected from by the immune system.
Surgery can lead to bleeding and infection. Artifical hearts don't work as healthy as natural ones- parts of the heartr could wear out or the electric mototr could fail. Blood doesn't flow through it smoothly which can cause blood clots. Patients have to take drugs to keep their blood thin. this can cause problems if they're in an accident.
Artificial blood
Artificial blood is a substitute that keeps patitents alive even if they lose a lot of blood. This may give the person enough time to produce new blood cells. If not they willl need a blood transfusion.
Statins
Cholesterol is an essential lipid in the body. However too much of a certain type od cholesterol (LDL) can cause health problems. Having too much if thie cholesterol causes fatty deposits to form in the arteries which can lead to coronary heart disease. Statins are frugs that reduce the cholesterol. It reduces risks of strokes and heart attacks, it also increases the amount of good cholesterol (HDL) in the blood. They may also help other diseases. However, they are long-term drugs that must be taken regularly and there are risks people can forget. Statins have negative side effects such as kindey failure or liver damage. The effect is not instant.
Pacemaker
The rhythm of the heart is controlled by a group of cells in the right atrium that act as a natural pacemaker. These cells produce small electrical impulses which spreads to the surrounding muscle cells, causing them to contract. However, if thye stop working it causes serious problems. It can be solved using an artificial pacemaker
The blood
Components:
plasma
- The blood plasma is a yellow liquid that transports all the blood cells and other substances in the body. It carries waste carbon dioxide, urea formed in liver to kidneys and nutrients like glucose.
red blood cells-
Carries oxygen from lungs to cells in the body. Thier shape is a biconconcave disc which gives it a large surface area for abosrbing oxygen. They do not have a nucleus which allows for more room carry oxyygen. Contains a red pigment called haemoglobin which binds to the oxygen in the lungs to become oxyhaemoglobin.
white blood cells-
Defend against infection. They change shape to consume microorganisms in a process called phagocytis. Others (lymphocytes) produce antibodies to fight and antitoxins to neutralise toxins.
platelets
- Cell fragments that help the blood to clot at a wound to stop all the blood pouring out and to stop microorganisms getting in.
Blood vessels
Blood is carried around the body in three main types of blood vessels, each adapted for a different function:
Arteries
- Carries blood away from the heart. The heart pumps blood at high pressure so the artery walls are strong and elastic. The walls are thicker than the lumen (hole). They contain layers of muscle to make them strong. The blood is bright red because it is oxygenated.
Capillaries
- Arteries branch into capillaries. They are tiny and carry blood close to cells to exchange substances with them. They have permeable cells so substances can diffuse. Their walls are one cell thick to increase the rate of diffusion by decreasing the distance over which it occurs.
Veins
- Carries blood back to the heart. Capillaries join to form veins. The blood is at lower temperature in the veins so the walls do not need to be as thick as artery walls. They have a bigger lumen to help the blood flow despite the low pressure. They also have valves to keep blood flowing in the right direction. The blood is normally dark red because it does not have oxygen.
Lungs and gas exchange
The lungs are found in the thorax and protected by the ribs. The air inhaled goes through the trachea which split up into two tubes called bornchi, one going to each lung. the bronchi split up into smaller tubes called bornchiokes which end at small bags called alveoli where gas exchange takes place. These are surrounded by capillaries where oxygen diffuses out of the alveolus and carbon dioxide diffuses in. They have a large surface area which makes diffusion more efficient.
Plants
Plant tissues
Epidermal tisssue - Covers tissue over surfaces to protect
Palisade mesophyll tissue - contains lots of chloroplasts which carry out of photosynthesis
Spongy mesophyll- tissue for photosynthesis but also had big air spaces and large surface area to make the diffusion of gases easier.
Xylem and phloem - transport tissues
Meristem tissue - Found at growing tip of shoots and roots and is able to differentiate.
Organs
Roots
Stem
Leaves - There are epidermal, mesophyll, xylem and phloem tissues. The epidermal tissues are covered with a waxy cuticle, which helps to reduce water loss by evaporation. The palisade layer had lots of chloroplasts and are beneath epidermal tissues at the top of the leaf to get a lot of light. The xylem and phloem form a network of vascular bundles next to the palisade mesophyll layer. The tissues of leaves are also adapted for gas exchange.The spongy mesophyll tissue increase diffusion due to air spaces. The lower epidermis is full of little holes called stomata, which let CO2 diffuse into the leaf. The opening and closing of stomata is controlled by guard cells. When guard cells are turgid the stomata open but when they are flaccid the stomata close.
Transpiration and translocation
Translocation
Phloem tubes:
Phloem tubes transport food. They are made of living cells with small pores to allow cell sap to flow through. They transport food substances made in the leaves. The transport goes in both direction and this process is called translocation.
Transpiration:
Xylem tubes:
Xylem tubes are made up of dead cells and are strengthened with a material called lignin. They carry water and minerals from roots to leaves. The movement of water from roots, through xylem and out of the leaves is called the transpiration stream.
Transpiration is the evaporation and diffusion of water from a plant's surface. Most transpiration happens at leaves. The evaporation creates a slight shortage of water in leaves and so more is drawn up through the xylem vessels and this is in a constant cycle. Water escapes because leaves have stomata and when they open for gas exchange water diffuses since there is more water in the plant than the air outside.
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Factors affecting transpiration
Light intensity- the brighter the light the greater the transpiration rate . In the dark photosynthesis can't happen so stomatas stay closed as they do not need to be open to let CO2 in and so water can not escape.
Temperature- the warmer it is the faster transpiration happens because the particles have more energy.
Air flow- The better the air flow around a leaf, the greater the transpiration rate. If the air flow is poor around a lead, the water vapour surround the leaf and doesn't move away so diffusion does not occur as quickly because there is water in the plant and outside of it. If the airflow is good, diffusion occurs since the air is low concentration.
Humidity- The drier the air around a leaf the faster transpiration happens.If the air is humid, there's a lot of water in it already so there's no difference vetween in and outside of the plant.
If a plant loses too much water, it will wilt which reduces its surface area so available water does not evaporate and the stomata close whiich stops photosynthesis and risks overheating but it reduces water loss.