Transport in plants, Circulatory system, Immune system, Respiratory system

Chapter 7

Plants

Xylem and Phloem (Vascular Bundles) - Vessels close together that make the transport system in plants in order to transfer nutrients in the soil from the roots of the plant into the stem and leaves. They also help to support the leaves, holding them out flat to capture sunlight.

Xylem - Plant tissue used to transport water and mineral ions, helping support the plant. Its made from hollowed-out dead, empty cells that have the ends removed to make a tube for water to pass through.

Phloem - Plant tissue made of living cells joined end to end, used to transport substances such as sucrose and amino-acids in translocation.

Sequences of tissues through which water flows:

• root hair cells (osmosis)

• root cortex cells (osmosis)

• xylem vessels

• stem

• leaves

• mesophyll cells

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Water loss structure:

1. water moves from the xylem vessels to mesophyll cells by osmosis.

2. water evaporates from the surface of the mesophyll cell walls.

3. the air spaces in leaf contain water vapour.

4. water vapour diffuses out of the air spaces through the stomata, into the atmosphere.

Transpiration - The loss of water vapour from the mesophyll cell surface due to evaporation. Inside the leaf, water molecules escape from the moist surfaces of the spongy mesophyll cells (evaporation) and pass through the stomata into the atmosphere (transpiration).

Translocation - Occurs in the phloem vessels and involves the transport of amino-acids and sucrose. Amino-acids and sucrose are produced in the leaves before being transported to the roots for storage. Later, they are transported to regions where they are used in respiration and for growth.

Source - Part of a plant that produces sucrose and amino-acids to be transported to other parts.

Sink - Part of a plant where sucrose and amino-acids are stored or used for respiration and growth.

Factors affecting the rate of photosynthesis

• Supply of raw materials (carbon dioxide and water)

• Quantity of sunlight (provides energy for reactions)

• Temperature (affects the activity of enzymes)

Why does water move from the soil to the top of the plant - Water molecules are drawn up the xylem by transpiration pull, (not osmosis). Water molecules are cohesive meaning they stick together. This means that as the water evaporates at the leaf and diffueses out of the stomata, more water is drawn up the plant from the roots.

( structure of the vascular bundles + pathway of water in a plant )

Circulatory system

Function of the circulatory system - don’ts the main transport in all mammals and humans, its made up of blood vessels such as arteries, veins and capillaries in which blood travels around the body carrying oxygen, nutrients and waste products. + consists of the heart that pumps blood.

Single and Double circulatory system :

Fish have a Single Circulatory System meaning that their heart only has 2 chambers, and blood passes through it only once on a complete circuit around the body. (fish do not have lungs and do not need to separate deoxygenated blood from oxygenated blood).

Mammals have a Double Circulatory System meaning that their heart has 4 chambers and blood passes through the heart twice to complete one circuit around the body. (they do need to separate deoxygenated blood from oxygenated blood).

( structure of the heart )

Blood Vessels

Artery - Blood vessel that carries blood away from the heart. This blood is at high pressure since it was just forced out of the ventricles muscles, so they need strong walls to withsand the high pressure.

Artery Structure -

• thick outer wall

• thick layer of muscles and elastic fibres

• smooth lining

• small lumen

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Veins - Blood vessel that carries blood into the heart. They carry low pressured blood so they dont need as strong walls, and they have valves to keep blood flowing in the correct direction.

Vein Strucutre -

• fairly thin outer wall

• thin layer of muscles and elastic fibres

• smooth lining

• large lumen

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Capillaries - Arteries eventually divide into smaller, thiner vessels called capilarries. They deliver blood containing oxygen and nutrients close to every cell in the body. Most of the pressure is lost so no need for strong walls, having thin walls lets substances get in and out easily.

Capillary Structure -

• wall made of a single layer of cells

• very small lumen

Coronary Heart Disease - The process of coronary arteries becoming blocked. Cholesterol deposits can build up inside the walls of arteries including coronary arteries. This makes the artery wall stiffer and the lumen narrower which makes it difficult for blood to flow through. This might lead blood clots to form and block the arteries, meaning the cardiac muscle wont get oxygen, it wont be able to do aerobic respiration, muscle wont have energy and the heart will stop beating.

Preventing CHD -

• not smoking any cigarettes

• taking care of your died (try to prevent eating lots of fats)

• regulary exercise

Pulse - The expansion and relaxation of an artery caused by the heart pushing blood through it.

Sequence of events during a heartbeat -

• muscles in the heart are relaxed, blood flows into the heart

• muscles in walls of atria contract, muscles of ventricles remain relaxed. blood is forced from the atria into the ventricles

• muscles in walls of ventricles contract, blood is forced out of the ventricles into the arteries.

Blood - Liquid containing of cells. The liquid is called plasma and the cells are; red blood cells, white blood cells, and fragments called platelets.

Red Blood Cells - Red cells that contain haemoglobin, carrying oxygen. Haemoglobin is a protein and contains iron. Haemoglobin combined with oxygen is called oxyhaemoglobin, it releases oxygen where the oxygen supply is low. This happens when blood passes through capillaries close to cells that are respiring, using up oxygen. Red blood cells do not have a nucleus or mitochondria, the lack of a nucleus means that there is more space for packing in millions of molecules of haemoglobin. They are Biconcave discs - flat discs with a small size and large surface area.

White Blood Cells - Blood cells containing a nucleus. They can squeeze out through the walls of blood capillaries into all parts of the body. Some white blood cells do Phagocytosis which is destroying pathogens by engulfing and destroying them, these are called Phagocytes. Other white blood cells produce Antibodies, they are called Lymphocytes.

Platelets - Small fragments of cells with no nucleus. They are made in the red bone marrow and are involved in blood clotting. Blood clotting stops pathogens from getting into our body through breaks in the skin, and prevents too much of blood loss. Platelets stick together to form clumps. The fibres + trapped red blood cells + clumps of platelets = form a blood clot.

Plasma - Mostly water, many substances are dissolved in it. Soluble nutrients such as glucose, amino acids and mineral ions are carried in the plasma. Plasma also transports hormones such as adrenline and waste products, including carbon dioxide and urea.

Chapter 8

Pathogens - Microorganisms that cause diseases, such as a virus. All viruses are composed of a protein coat surrounding genetic material. Once inside the body, some pathogens damage our cells by living in them and using up their resources. Others cause harm to cells and body systems by producing waste products called toxins, that cause symptoms and make us feel ill.

Transmissible Diseases - The movement of a pathogen from one host to another. The entery of the pathogen into the body is called infection. This could happen by 2 ways: Direct contact and Indirect contact.

Direct Contact - transmitted when an infected person’s blood comes into contact with another persons blood.

Indirect Contact - could happen through breathing in droplets containing pathogens, touching a surface that someone with the pathogen has touched, eating food or drinking water that contain pathogens, or contact with animals that are carrying pathogens.

Body defences againts pathogens -

• Skin : prevents pathogens from entering the body. If skin is broken blood clots will form and seal wounds.

• Hairs in nose : help to filter particles from the air, which could contain pathogens.

• Mucus in airways : traps bacteria. Later on are swept up to the back of the throat and are swallowed, rather then letting them get into the lungs.

• Bad smell and taste : if we smell or taste something that is bad we wont be wanting to eat it.

• Stomach hydrochloric acid : low pH level kills a lot of bacteria in our food.

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Controlling the spreading of transmissible diseases - Filter and treat water to get rid of dirt and other microorganisms to have clean water supply. Prepare food following simple rules for good food hygiene such as washing hands before cooking, keeping animals away, keep food in correct and suitable temperature, keep raw meat away. Keeping your body clean; cleaning our body with soap and shampoo to get rid off oils and dirt, and brushing teeth twice a day or using mouthwash. Taking care of the waste food and rubbish that contain bacteria and dangerous chemicals that we throw away each year, making sure it doesnt harm the enviorment. Treating sewage before allowing it in rivers and seas because they contain bacteria and other microorganisms that are most likely pathogens and can cause harm to the enviorment and make humans ill.

The Immune Response - The process of the immune system recognizing antigens and producing antibodies to attack and destroy the antigens.

Antibodies - A protein molecule with a particular shape that is complementary to the shape of an antigen molecule. The antibody molecules bind with the antigen and directly kill the pathogen. In other cases, the antibodies stick the pathogens together, this stops the pathogens dividing or moving, making it easier for phagocytes to destroy them.

Memory Cells - Long-lived cells produced by the devision of lymphocytes that have detected their antigen, that remain in the blood and other pars of the body so if the same kinf od pathogen gets into the body again in the future, those memory cells will be ready.

Active Immunity - Long-term defence againts a pathogen by antibody production in the body. Active immunity can be developed by: having the disease and rcovering it, being vaccinated.

Passive Immunity - Short-term defence gained by injecting. Antibodies dies againts a pathogen and does not produce memory cells.

Vaccination - Humans getting a vaccine that may contain weakened or dead viruses or bacteria that normally cause disease. Some vaccines do not contain complete viruses or bacteria, only their antigens. When the weakend pathogens or their antigens enter the body, they are recognized by lymphocytes that can make antibodies with a complementary shape to their antigens. The lymphocytes multiply, produce and also make memory cells. So once the virus or bacteria gets into the body in the future, they will be attacked and destroyed immidietly. We also vaccinate humans in order to eradicate serious diseases caused by viruses.

Chapter 9

Gas Exchange - When an organism breathes in air, its gas exchange system diffuses oxygen into the blood and removes carbon dioxide. The areas where the oxygen enters and carbon dioxide leaves are called “gas exchange surfaces”.

Structure of the Respiratory System :

Larynx - A voice box below the epiglottis that contains vocal cords. these vocal cords can be tightened by muscles and make sounds when air passes over them.

Trachea - Tube through which air travels from the nose or mouth to the lungs. It has rings of cartilage in its walls to support it.

Bronchi / Bronchus - In the thorax, trachea divides into 2 parts (or branches) right and left bronchi. Each bronchus goes to each lung and then branches out into smaller tubes called bronchiole.

Bronchiole - A small tube that takes air from a bronchus to every part of the lungs.

Alveoli - Many tiny air sacs closely wrapped in capillaries at the end of each bronchiole, where gas exchange takes place. Oxygen diffuses across the -one-cell-layer-thick- walls of the alveoli into the blood and carbon dioxide diffuses the other way.

Lungs - Two parts of the human gas exchange system. each lung is filled with many alveolus where oxygen diffuses into the blood. Since they are so full of air spaces thry feel very light and spongy to touch. Lungs are supported with air through the trachea.

Intercostal muscles and Diaphragm - In order for air to move in and out of our lungs we must change the volume of the thorax. We make it larger for air to suck in and then smaller for air to squueze out (which is called breathing). We have muscles that contract and relax, helping us to breathe. they are; Intercostal Muscles (muscles between our ribs) and Diaphragm (muscles and tissues underneath our lungs and heart).

Inspired air and Expired air - Inspired air is the air that we breathe in, it contains 20-21% of oxygen, 0.04% percentage of carbon dioxide and a variable percentage of water vapour. Expired air is the air that we breathe out, it contains 16% of oxygen, 4% of carbon dioxide and usually a very high percentage of water vapour.

Effects of exercise on breathing rate - Sometimes cells may need a lot of oxygen very quickly. If we are doing an exercise, the muscles in our body will contract much harder and more frequently than usual so they require more energy. The cells in the muscles combine oxygen with glucose as fast as possible to release extra energy for muscle contraction. A lot of oxygen is needed for this, meaning we will breathe deeper and faster to get the oxygen in the blood but eventually we reach a limit, our heart and lungs cannot supply oxygen any more faster while our muscles continue to contract and still require energy. When this happens, our cells start to break down glucose without combining it with with oxygen to make energy (anaerobic respiration), even though it is not as efficient as aerobic respiration. In anaerobic respiration, in order to make energy from glucose it also produces lactic acid. Once we stop the exercise we will have a lot of lactic acid in the muscles and blood which is needed to be broken down by combining it with oxygen in the liver (which is done by aerobic respiration). So even though we no longer need extra energy, we continue to breathe faster and deeper, our heart rate continues to be high, in order to get extra oxygen to be able to break down the lactic acid formed in the body.

Oxygen Debt - When you stop needing the extra energy that came from anaerobic respiration you keep on breathing fast so that extra oxygen is avaliable for the break down of the accumulated lactic acid. The extra oxygen requirment is called oxygen debt.

Uses of Energy contained in Respiration :

• contracting muscles, so we can move parts of the body

• making protein molecules by linking together amino acids into long chains

• cell division, so that we can repair damaged tissues and can grow

• active transport, so that we can move substances across cell membranes up their concentration gradients

• growth, by building new cells which can then divide to form new cells

• producing heat inside the body, to keep the body temperature constant evven if the enviroment is cold

• transmitting nerve impulses, so that we can transfer information quickly from one part of the body to another.

Aerobic Respiration - Most of the time our cells release large amount of energy from glucose by combining it with oxygen. This happens in a series of small steps, each controlled by enzymes, and most steps take place in the mitochondria. When doing aerobic respiration no alcohol or lactic acid is produced (CO2 is produced).

glucose + oxygen → carbon dioxide + water

C6H12O6 + 6O2 → 6CO2 + 6H2O

Anaerobic Respiration - Releasing energy from glucose without combining it with oxygen. Anaerobic respiration happens in the cytoplasm. It is not as efficient as aerobic respiration and not much energy is released per a glucose molecule. When cells respire anaerobically they make lactic acid, and no carbon dioxide Is produced. This happens when we are doing vigorous exercises and are not able to supply the muscles with oxygen any more faster, so the cells are able to release at least some energy without oxygen, just glucose, until oxygen is avaliable again.

Glucose → lactic acid

Breathing and Ventilation - Breathing is the process of changing the thorax volume for air to get in and out with the use of Intercostal muscles and the Diaphragm, we make it large for air to suck in and small for air to squeeze out. Ventilation is the movement of air into and out of the lungs, keeping the lungs well and supplied with oxygen by breathing movements.