bio chapter 2 - organisation

• 24 - cell organisation

• cells are the blueprints for all living things

• tissues are collections of different cells working together with the same function

• tissues make up organs which have specific functions

• organs work together in organ systems which complete specific functions

• finally, organ systems make up organisms

• cells become specialised for a specific function through differentiation, which occurs in the development of the organism

• epithelial cells covers the insides of some body parts - the gut, and together they make epithelial tissue which covers the inside of the stomach

28 - more on enzymes and digestion

• enzymes are biological catalysts, they speed up rate of reaction without being used up or changed, they reduce the need for heating for chemical reactions in the body, as heating can damage the cells in the body - they are large proteins made of amino acids, folded up into shapes

• they have active sites that have certain shapes to fit to certain substrates that they catalyse - lock and key theory

• enzymes can be denatured (change shape) if pH levels change the bondsin the enzyme change, high temps or heavy metals or toxins bind to it

• salivary glands - create amylayse enzyme in the saliva

• liver - where bile is produced - neutralises stomach acid and emulsifies fats

• gall bladder - where bile is stored before it’s released into the small intestine

• large intestine - where excess water is absorbed from food

• rectum - where waste is stored before passing out the anus

• stomach - pummels the food with muscular walls, produces the protease enzyme - pepsin, produces hydrochloric acid to kill bacteria and keep the stomach at optimum pH for protease enzymes (2)

• pancreas - produces lipase, amylase and protease - released into the small intestine

• small intestine - produces lipase, amylase and protease to complete digestion

30 - the lungs

• the lungs are located in the top part of your body (the thorax)

• its separated from the lower part of your body by your diaphram

• air travels through your windpipe (trachea) and splits off into 2 tubes (bronchi), each one called a bronchus

• the bronchus are smaller tubes into the lungs that split off into smaller tubes called bronchioles, which are inside your lungs

• the bronchioles carry air to alveoli inside the lungs, this is where gas exchange takes place

• the lungs are protected by the ribs, with the heart in-between them, and the lungs are surrounded by plueral membranes and intercostal muscle

• the lungs contain millions of air sacs called alveoli

• the alveoli are surrounded by a network of blood capillaries

• the blood passing next to the alveoli has a high concentration of carbon dioxide as it has just returned from the lungs

• alveoli contain the oxygen that you have breathed in, so the high conc of oxygen inside the alveoli diffuses into the bloodstream (where there’s a low conc of oxygen)

• the same happens with carbon dixoide, the blood has a high conc of CO2, so it diffuses into the alveoli where there’s a low conc, ready to be breathed back out

• oxygen - in

• carbon dioxide - out

• when the blood reaches the body cells, the oxygen is diffused into them, as the blood stream has a high oxygen conc, so it diffuses into the body cells where there is a low conc of oxygen

• at the same time, CO2 diffuses out of the body cells (where there’s a high conc) and diffuses into the bloodstream (where there’s a low conc) to be carried back to the lungs

• breathing rate = number of breaths / number of minutes

31 - the heart

• humans have a double circulatory system - 2 circuits joined together

• the first pumps deoxygenated blood to the lungs to recieve oxygen then pumps it back to the heart - this is the right ventricles job

• the second pumps the oxygenated blood all around the body and its organs, so that oxygen is delivered to body cells so that they can function, the blood then becomes deoxygenated and returns to the heart to be pumped out to the lungs again - this is the left ventricles job

• the heart is a pumping organ - its walls are mostly made out of muscle tissue

• the heart has coronary arteries that collect oxygenated blood for itself so it can work, they branch off the aorta

• the heart has valves to ensure blood flows in the right direction and prevent backflow

• the heart has 4 chambers (right and left atrium, right and left ventricle) this is how it pumps blood around the body

• 1 - blood enters the 2 atria through the vena cava (right) and the pulmonary vein (left)

• 2 - these carry the blood into the right and left atrium, the atria contract and sends the blood to ventricles

• 3 - the ventricles contract and send the blood to the pulmonary artery (right) and the aorta (left), where the blood leaves the heart - from the right side, to the lungs, from the left side, to the rest of the body

• 4 - the blood flows to organs through arteries and return to the heart through veins

• 5 - the atria fill and the cycle begins again

• your resting heart rate is controlled by a group of cells called a pacemaker, that produce small electrical impulses to the muscle cells of your heart, so they contract and pump blood all at the same time

• the pacemaker is found in the wall of the right atrium

• you can have an atrificial pacemaker if your heart beats are irregular, it has a wire going to the heart that contains an electrical current to keep the heart beating regularly

32 - blood vessels

• arteries - carry the blood away from the heart

• capillaries - exchange materials in the blood to tissues (food, oxygen and remove waste/co2)

• veins - carry blood to the heart

• structure of artery - the heart pumps blood out at a high pressure, so the arteries have strong elastic walls

• small lumen (that maintains high pressure as the blood travels) that contain thick layers of muscle made of elastic fibers that allow them to stretch and spring back

• structure of a capillary - arteries branch into capillaries

• the walls of a capillary are permeable to allow materials in the blood to easily diffuse out of it and into the tissues

• the walls are only 1 cell thick - increases the rate of diffusion by decreasing the distance the materials have to travel

• they’re very tiny to be closer to the cells they exchange materials to

• structure of veins - capillaries join together to make veins

• they have large lumens, because they don’t have to flow at a high pressure

• since the blood is at a lower pressure, they have thin walls, with thin elastic fibers

• they have valves to keep the blood flowing in the right direction

• rate of blood flow = volume of blood / number of minutes

33 - blood

• platelets help blood to clot when an injury occurs, making a scab and stopping bacteria from entering through the cut and stopping you bleeding out

• protecting you from infection and ensuring you don’t loose too much blood

• they are small cell fragments with no nucleus, lack of them causes excessive bleeding and bruising

• haemaglobin is the pigment that makes blood red, in the lungs it binds to oxygen to make oxyhaemoglobin

• in the body tissues, oxyhaemoglobin splits up into haemoglobin and oxygen to release oxygen to the body cells

• red blood cells carry oxygen around the body and carbon dioxide out of it, they have a biconcave shape, giving them a large surface area which helps absorb oxygen

• they also don’t have a nucleus, leaving more room to carry oxygen

• white blood cells fight the pathogens that enter your body by producing antitoxins to neutralise toxins produced by micro-organisms

• they also produce antibodies that fight micro-organisms

• they can also engulf pathogens in a process called phagocytosis

• they do have a nucleus

• plasma is a liquid that carries material around the body - glucose and amino acids are taken from the gut and taken to the cells, as well as: CO2 from the organs to the lungs, urea from the liver to the kidneys, hormones, proteins and antibodies and antitoxins produces by white blood cells

34 - cardiovascular disease

• coronary heart disease is when arterys getting oxygenated blood to the heart are blocked by fatty materials building up, narrowing them and restricting blood flow and causing lack of oxygen to the heart, resulting in a heart attack

• stents are tubes that are inserted into arteries

• they hold the coronary arteries open to allow the blood to flow normally, providing the heart with oxygenated blood

• they lower the risk of a heart attack for people with coronary heart disease

• they are effective for a long time and recovery time from surgery is fast

• however, the surgery can cause infection and there is a risk of patients developing a blood clot by the stent - this is called THROMBOSIS!!!!!

• statins are drugs that reduce the amount of ‘bad’ cholesterol in the blood

• having too much ‘bad’ cholesterol can cause fatty deposits to build up inside arteries - can lead to coronary heart disease

• cholesterol is an essential lipid that your body produces and needs to function

• pros of statins - reduces the amount of bad cholestrol in your body, so decreases the risk of heart attacks, strokes and coronary heart disease, some people also argue they fight other diseases, by removing the bad cholestrol in your blood, you have more good cholestrol, which can help remove bad cholestrol

• cons of statins - long - term drug that have to be taken everyday, someone may forget to take them, they can cause negative side effects (headaches, kidney failure, liver damage and memory loss), the effect of them isn’t instant

35 - more on cardiovascular disease

• if a patient has heart failure, they will have a heart transplant from a donor heart

• if it’s not the right type/ if there no hearts available, the person will be given an artificial heart

• they are mechanical devices that pump blood for the persons whos heart has failed, this is only temporary until donor heart is found but reduces the need for one

• they are less likely to be rejected than a donor heart, as they’re made from metals and plastics so the body doesn’t recognise them as foreign and don’t attack them like they would with living tissue

• the surgery for an artificial heart is dangerous and can lead to bleeding and infection, they’re not as effective as real hearts as parts of it could wear out or the electric motor could fail

• blood doesn’t flow through artificial hearts as smoothly, which can lead to blood clotting and strokes - this means that the patient has to take blood thinner drugs, which can cause issues with bleeding if they’re injured

• the valves in the heart can be damaged or weakened by heart attacks, infection and old age

• the damage may cause the valve tissue to stiffen, so it won’t open properly

• it may become leaky, allowing blood to flow in both directions, meaning it doesn’t circulate properly

• severe valve damage can be treated by replacing it with a biological valve (one from a human or mammal) or a man-made valve (a mechanical valve)

• the surgery isn’t as drastic, but there can be problems with clotting

• when someone looses a-lot of blood, the heart can still pump around what is left to get oxygen to the cells

• artificial blood (a saline substitute) can be used to replace the missing blood, the person will stay alive even if they’ve lost 2/3 of their blood, it’s safe so long as no air bubbles get into the blood and gives the person time to make new red blood cells

• if they don’t make enough red blood cells, they’ll have to have a blood transfusion

• scientists are working on a product that replaces the lost red blood cells without the patient having to make more

36 - health and disease

• health is the state of physical and mental wellbeing

• disease can cause ill health

• communicable diseases are ones that spread from person to person or animal to people

• they’re caused by bacteria, viruses, vectors, parasites and fungi

• examples are : measles and malaria

• non-communicable diseases are ones that don’t spread

• they usually last a long time and progressively worsen

• examples are : coronary heart disease, asthma and cancer

• diseases sometimes interact to create physical and mental issues that seem unrelated

• a bad immune system can mean you contract influenza (flu), as your body is too weak to fight the pathogens

• infection with hepititus can cause infections in the liver, leading to liver cancer

• HPV causes cervical cancer in women

• immune system reactions can cause skin rashes or worsen asthma

• depression can manifest when someone is suffering from an illness, especially if it’s life threatening or stop them from doing everyday activities

• your living conditions can effect your health: if you have a bad diet, it could lead to illnesses such as diabetes, if you have bad living condition/are in poverty, you won’t be able to afford/have access to healthcare or be able to buy condoms to prevent STDs and being under lots of stress can cause health issues

  37 - risk factors for non-communicable disease

• risk factors increase the likelihood of you developing an illness

• risk factors include : your lifestyle (diet, exercise) , your environment (air pollution), and substances inside your body (abestos fibers, found in buildings, built up in lungs and caused cancer)

• lifestyle factors have an impact locally, nationally and globally, your choices effect the spread of disease in your town, city and the world

• example : in developed countries, people have high incomes and can afford to buy high-fat foods, leading to diabetes and nationally people from deprived areas are more likely to smoke, meaning lung cancer is more prevalent in those areas

• some risk factors can cause disease directly: alcohol and smoking can damage a baby, obesity can lead to diabetes, smoking causes cardiovascular disease, lung cancer and lung disease, drinking alcohol can cause liver disease and cancer can be caused by exposure to carcinogens

• risk factors don’t usually cause the disease alone, they cause symptoms which trigger the disease - correlation doesn’t equal cause

• people die from non-communicable disease and their loved ones suffer

• families will have to move or leave work to be able to look after someone with a non-communicable disease, they may also have to pay to have them looked after specially

• it costs the NHS and the government lots of money to provide free healthcare to those with non-communicable disease

• the number of people able to work also effects the economy

38 - cancer

• cancer is caused by a tumour

• changes occur to a cell which lead to uncontrollable growth and division - this becomes a tumour

• not all are cancerous, they can either be benign or malignant

• benign tumours - the tumour grows in one place (usually a membrane) until there is no room left, they do not spread to or effect living tissues, they’re usually harmless and not cancerous

• malignant tumours - the tumour grows and spreads to other living tissue, they can break off and travel through the bloodstream to effect living tissue everywhere in the body and form secondary tumour - they’re very dangerous and cancerous

• risk factors don’t mean you’ll definetly get cancer, but it increases the risk that you will

• smoking - causes mouth, bowl, cervical and lung cancer

• UV rays - sunbeds and too much time in the sun causes skin cancer

• viruses - hebatitus b and c can lead to liver cancer

• obesity - can cause bowl, liver and kidney cancer

• inheriting faulty genes can make you more likely to get cancer

• example : mutations in the BRCA gene can cause breast and ovarian cancer

39 - plant cell organisation

• tissue functions and their structures:

• upper epidermis - translucent to allow sunlight to pass through to palisade

• epidermis tissue - covers the leaf - waxy layer to prevent water loss by evap

• palisade tissue - where most photosynthesis happens - close to the top to get the most sunlight - contains lots of choloroplasts

• (spongy) mesophyll tissue - where gases diffuse in and out/where gas exchange occurs - contains lots of big air spaces which increase rate of diffusion by decreasing the area

• xylem and phloem - transport substances (water, mineral ions, food) to the roots, stem and leaves of the plant and take glucose away - also help support the plant structure - form a network of vascular bundles to help transport substances

• meristem tissue - can differentiate into many types of plant cell - allows plant to grow - located near the growing tips of shoots and roots

• guard cells - at the bottom - control the opening and closing of the stomata in response to environmental conditions

40 - transpiration and translocation

• phloem cells - transport food

• structures - made of columns of elongated living cells with small pores in the end walls to allow cell sap (a liquid containing water and transported substances) to flow through - transport food substances (dissolved sugars) made in the leaves to the rest of the plant for immediate use or storage - can flow either way - this is called translocation

• xylem cells - transport water up

• structures - made up of dead cells joined end to end with no end walls in-between - they’re hollow, with a hole down the middle - they’re strengthened with a material called lignin - they carry water and mineral ions from the roots to the stem and the leaves - the movement of water from the roots, up the xylem an out of the leaves is the transpiration stream

• transpiration is the loss of water from a plant

• transpiration occurs using evaporation and diffusion

• water evaporates from the leaves, because stomata allow it to diffuse out, this is because the concentration is water in the leaves in higher than the air outside, so the water will move from the leaf and evaporate into the air

• since more water is lost from the leaves, the roots take more water up through the xylem cells, causing a constant transpiration stream

41 - transpiration and stomata

• guard cells are adapted to open and close stomata - their kidney shape helps them do this

• when the plant contains lots of water, the guard cells fill and go plump and turgid, which allows them to open so gases can be exchanged for photosynthesis

• when the plant contains little water, the guard cells go flaccid, which makes them close, meaning that water vapour doesn’t escape

• they have thick inner walls and thin outer walls to make opening and closing work

• they’re sensitive to light, so they close when it’s dark to ensure water doesn’t escape without missing out on photosynthesis

• they control both gas exchange and water loss

• light intensity - when it’s bright, more transpiration - stomata close at night, so little transpiration as photosynthesis doesn’t occur

• temp - when its hot, more transpiration - water particles have more energy

• air flow - better air flow, faster transpiration - good airflow = water vapour is swept away, maintaining a low conc of water in the air, meaning diffusion happens faster (high conc in leaf - low conc in air)

• humidity - drier air, faster transpiration - keeps a low conc of water in the air, meaning diffusion can happen quicker

• transpiration rate is effected by: light intensity, air flow, temperature and humidity

• to estimate the rate of transpiration: set up apparatus called a potometer and record the starting position of an air bubble , start a stopwatch and measure the distance moved by the bubble per unit time (m/s) - keep condition constant