S5 - Blood and Organs Flashcards
composition of blood: plasma
-the liquid which carries the components in the blood, e.g: cells, platelets, amino acids, hormones etc.
-plasma is important for the transport of carbon dioxide, digested food, urea, hormones and heat energy
composition of blood: red blood cells
-carry oxygen molecules from the lungs to all the cells in the body
-contain haemoglobin: a red protein that combines with oxygen to allow for transport
-no nucleus: to create more space for haemoglobin
-biconcave shape: to maximise surface area for oxygen to be absorbed
-flexible: so they can fit through very narrow blood vessels
composition of blood: white blood cells
-they are part of the immune system, which is the body’s defence against pathogens, there are 3 types:
1) Phagocytic wbc: one types of wbc can do a process called phagocytosis, where the pathogen is engulfed and killed + as they are able to do this with any type of pathogen it is a non-specific function
2) producing antibodies (lymphocytes): each pathogen has an antigen on their surface, which is a structure with a specific complementary antibody can bind to, once antibodies begin to bind to the pathogen, they start to clump together, resulting in it being easier for wbc to find them + if you become infected again with the same pathogen, the specific complementary antibodies will be produced at a faster rate. The individual will not feel the symptons of the illness, they are said to be immune
3) producing antitoxins: wbcs neutralise the toxins released by the pathogen by binding to them
human circulatory system: the heart
-the heart is an organ in the circulatory system, it carries oxygen and nutrients to every cell in the body and removes the waste products
-the heart pumps blood around the body in a double circulatory system, this means there are 2 circuits, mammals require this double system because the metabolic rate is higher and so need a faster system
system 1: right atrium
-deoxygenated blood flows into the right atrium and then into the right ventricle which pumps it to the lungs to undergo gaseous exchange
system 2: left atrium
-oxygenated blood flows into the left atrium and then into the left ventricle which pumps oxygenated blood around the body
structure of the heart:
-muscular walls to provide a strong heartbeat
-the muscular wall of the left ventricle is thicker because blood needs to be pumped all around the body rather than just to the lung like the right ventricle
-4 chambers that seperate the oxygenated blood from the deoxygenated blood: 2 atria above and 2 ventricles below
-valves to make sure blood does not flow backwards
-coronary arteries cover the heart to provide its own oxygenated blood supply
process of the heart:
- blood flows into the right atrium through the vena cava, and left atrium through the pulmonary vein
- the atria contract forcing the blood into the ventricles
- the ventricles then contract, pushing the blood in the right ventricle into the pulmonary artery to be taken to the lungs, and blood in the left ventricle to the aorta to be taken around the body
4) as this happens, valves close to make sure the blood does not flow backwards
structure of blood vessels:
arteries: carry blood AWAY from the heart
-layers of muscle in the walls make them strong
-elastic fibres allow them to stretch
-this helps the vessels withstand the high pressure created by the pumping of the heart
veins: carry blood TOWARDS the heart
-the lumen (the actual tube in which blood flows through) is wide to allow the low pressure blood to flow through
-they have valves to ensure the blood flows in the right direction
capillaries: allow the blood to flow very close to cells to enable substances to move between them
-one cell thick walls create a short diffusion pathway
-permeable walls so substances can move accross them
heart rate changes: exercise
-when exercising, muscles require energy and so will be respiring at a higher rate
-this means that the heart rate will increase in order for the heart to pump more oxygen and nutrients around the body and to remove the waste carbon dioxide from respiring muscle
-stroke volume will also increase, meaning that the heart will pump more powerfully as well as faster
-when anaerobic respiration occurs during high intensity exercises, such as sprintm an oxygen debt is created, which is then needed to be transferred around the body quickly so that the lactic acid produced by the anaerobic respiration does not cause muscle cramps
heart rate changes: adrenaline
-adrenaline is a hormone produced by the adrenal glands above the kidney
-it is responsible for the ‘fight or flight’ reaction
-increased heart rate to deliver more oxygen to respiring muscles that will be contracting more frequently
-increased breathing rate, so more gas exchange occurs and more oxygen diffuses into the blood and more carbon dioxide diffuses out
-blood flow is diverted away from digestive system and towards respiring muscles
-adrenaline also causes other body changes, such as pupils to dilate to let in more light
coronary heart disease:
-the coronary arteries supply blood to the heart and in CHD these arteries become blocked, due to a build-up of fatty plaques (astherosclerosis). This can cause ischaemia (lack of blood and oxygen) which can eventually lead to a muscle death and therefore a heart attack
causes:
-Poor diet: a diet rich in saturated fat increases choresterol levels, which can increase the chance of fatty plaques building up + high levels of salt can increase blood pressure which damages the blood vessels and increases the chance of fatty deposists building up
-smoking: nicotine causes narrowing of blood pressure and increases blood pressure, which can increase the chance of a blockage in the coronary arteries
-stress: hormones produced in times of stress can increase blood pressure which can damage the vessel walls
