B2 - Animal Tissues, Organs And Organ Systems Flashcards
What is the heart?
The heart is an organ that pumps blood around the body in a double circulatory system
What is the function of the right ventricle?
Pumps deoxygenated blood to the lungs where gas exchange takes place
What is the function of the left ventricle?
Why does the left ventricle have a thicker muscular wall?
Pumps blood around the rest of the body
LV has a thicker muscular wall because it pumps blood around the body so requires a greater force
What are the disadvantages of a single circulatory system, for example in fish?
Blood looses a lot of pressure as it passes through the gills before reaching the organs
Results in the circulation of blood to the organs being slow so the oxygen supply is delayed and not sufficient
Describe the double circulatory system
Deoxygenated blood is pumped from the heart to the lungs, where it collects oxygen
This oxygenated blood returns to the heart
The heart now pumps the oxygenated blood to the organs, where the blood transfers its oxygen to the body cells
The blood then returns back to the heart
What are advantages of a double circulatory system?
The blood passes through the heart twice, so it can travel rapidly to the body cells
This results in fast delivery of sufficient oxygen to the cells that require it for respiration
Describe the pattern of blood-flow through the heart
Blood flows into the left atrium through the pulmonary vein and the right atrium through the vena cava
The atria contract, forcing blood into the ventricles
The ventricles contract, forcing blood In the right ventricle into the pulmonary vein to be taken to the lungs, and blood in the left ventricle to the aorta to be taken around the body
As this happens, valves close to prevent the back flow of blood
The atria fill again and the cycle repeats
What is natural resting heart rate controlled by?
A group of cells located in the RIGHT ATRIUM that act as a pacemaker
Suggest what a doctor should do if the natural resting heart rate of a human becomes irregular
May use an artificial pacemaker as they correct irregularities
What is an artificial pacemaker?
Artificial pacemakers are electrical devices used to correct irregularities in the heart rate
What is the function of the coronary arteries?
Provide oxygen to the muscle cells of the heart
This oxygen is used in cellular respiration to release energy for CONTRACTION
What is the function of the heart valves?
Stop the back flow of blood into the atria when the ventricles contract
What is the function of the vena cava?
Brings in oxygenated blood from the body
Suggest the effects of leaky / faulty valves on an athlete
Leaky valves result in the back flow of blood into the atria
This results in less oxygenated blood leaving the heart
Therefore, less oxygen is supplied to body cells and working tissues
This means that less cellular respiration takes place and so less energy is released
This effects the athlete as it results in tiredness, fatigue and poor athletic ability
The body contains three different types of blood vessel.
What are they?
Arteries
Veins
Capillaries
What is the function of the three blood vessels?
Arteries transport high pressure blood away from the heart to the organs
Veins transport low-pressure blood back to the heart
Capillaries surround tissues for the exchange of substances through diffusion or active transport
How are arteries adapted to their function?
Thick muscular wall to withstand high pressure
Elastic fibres that stretch when the surge of blood passes through and recoil in between surges to keep blood moving
Small lumen
Smooth muscle
How are veins adapted to their function?
Large lumen
Thin muscular wall as it transports low-pressure blood
Contain valves to stop the back flow of blood into the atria
How are capillaries adapted to their function?
Very small lumen
One cell thick for a short diffusion distance of substances between the blood and body cells
Permeable wall, so substances can easily diffuse in and out
Compare the structure of arteries, capillaries and veins
Size of lumen: Arteries have a small lumen, whereas veins have a large lumen. Capillaries have the smallest lumen
Thickness of wall: Artery is thickest, whereas veins are thinner. Capillaries are the thinnest; one cell thick
Valves present: Veins contain valves to prevent the back flow of blood, whereas capillaries do not have valves. Arteries typically lack valves
What is blood?
Blood is a tissue consisting of plasma, in which the red blood cells, white blood cells and platelets are suspended.
What is the function of blood plasma?
A liquid substance that transports dissolved substances around the body
Examples:
- Glucose
- Carbon dioxide
- Amino acids and hormones
- Urea to the kidneys
What is the function of platelets?
Platelets are small fragments of cells that begin the process of blood clotting to stop bleeding following vessel damage
What is the function of white blood cells (WBCs)?
White blood cells form part of the immune system. Protect against infection by destroying microorganisms
Methods of defence:
- Phagocytosis (engulfing pathogens)
- Producing antibodies and antitoxins
What is the function of red blood cells? (RBCs)
Transport oxygen around the body to respiring cells
What are the different blood components?
Plasma
Platelets
WBCs
RBCs
How are red blood cells adapted to their function?
Biconcave shape. This provides a large surface area to increase rate of diffusion of oxygen molecules
No nucleus, allowing more space for the oxygen-carrying molecule haemoglobin
Contain haemoglobin. Forms oxyhemoglobin in the lungs and haemoglobin and oxygen in the organs
Thin for a short diffusion pathway
Flexible so are able to go through capillaries
Under a microscope, how are the different blood components observed?
- Set up a light microscope (exam may use electron microscope) and a sample of blood on a slide the same way outlined in the first required practical
- RBCs are biconcave and red, plasma is the liquid between the components, platelets are tiny fragments (typically dots) and white blood cells are usually larger and distinct with internal structures
How are white blood cells adapted to their function?
Contain a nucleus. This has DNA which encodes the instructions that the WBC has to do as part of its function
Give three uses of donated blood in medicine
- Can replace blood lost during injury
- People are given platelets extracted from blood to help in the process of clotting
- Proteins extracted from blood can be useful in the production of antibodies
What are the risks of using blood products?
- Many diseases can be transmitted via blood
- In a blood transfusion, if the donated blood does not have the same blood type as the patient’s, their body’s immune system will reject it and they may die
- However, in the UK, blood is screened for infections so the risk is extremely low (useful evaluation point)
What is coronary heart disease?
What is its long-term effect if not treated?
Layers of fatty material build up inside the coronary arteries, narrowing them
This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle. As a result, there is less respiration as glucose and other substances are not transported. This causes fatigue and less energy to be released, eventually resulting in stopping heart contraction and death
What are three methods of treating coronary heart disease: a non-communicable disease?
Statins (Drug)
Stents (Mechanical device)
Artificial hearts (Transplant)
What is a statin, stent and artificial heart?
Statins are drugs that reduce LDL cholesterol levels, slowing down the rate of fatty material deposit
Stents are mesh tubes used to keep the coronary arteries open
Artificial hearts are mechanical devices that pump blood
What are the advantages of using statins to treat coronary heart disease?
No surgery required
Easy to take
Reduces LDL cholesterol levels so directly lessens the effects of the disease
Reduce the chances of stroke
Increases the amount of HDL cholesterol
What are the disadvantages of using statins to treat coronary heart disease?
Have to take the drug for life. Someone could forget to take them
Effect of statins is not instant
Negative side effects such as liver problems
Stents are used more wisely when CHD causes a total blockage of a coronary artery.
What are the advantages of using stents?
Effective for many years
Blood can flow through the artery normally, so essential substances can be transported by blood plasma
Surgery is quick
What are the disadvantages of using stents to treat CHD?
Intensive surgery compared to statins that are oral drugs
Does not prevent other regions of the coronary arteries from narrowing (Good evaluation point)
Risk of infection and blood clotting
What is heart failure?
When the heart cannot pump sufficient blood around the body
What are the advantages of using artificial hearts to treat CHD?
Keeps the patient alive whilst waiting for a donated heart transplant
Allows the heart to rest as an aid to recovery
What are the disadvantages of using artificial hearts to treat CHD?
Risk of blood clotting
Parts of the heart could wear out, or the electrical motor could fall
Surgery can lead to bleeding or infection
What are the disadvantages of donated hearts?
Not enough to treat every patient with cardiovascular disease
May have to take drugs to stop the donated heart from being rejected by the immune system
What is health?
Health is the state of physical and mental well-being
What factors affect health?
Diet
Stress
Life situations
Diseases - both communicable and non-communicable
Describe how different types of diseases may interact
Defects in the immune system mean that an individual is more likely to suffer from infectious diseases
Viruses in cells can be the trigger for cancers
Immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma
Severe physical ill health can lead to depression and mental illness
What is epidemiology?
Studying the patterns of disease to determine risk factors
What are risk factors?
Factors that are linked to an increased chance of developing a particular disease
Risk factors can be…
Aspects of a person’s lifestyle (sedentary)
Substances in the person’s body or environment
What is a causal mechanism?
The processes or pathways through which an outcome is brought into being
A causal mechanism has been proven for some risk factors, but not in others.
What are some of these?
Poor diet, smoking and lack of exercise -> risk factors for cardiovascular disease
Obesity -> risk factor for Type 2 diabetes
Alcohol -> risk factor for poor liver and brain function
Smoking -> risk factor for lung disease and cancer
Carcinogens, including ionising radiation -> risk factor for cancers
What are the human and financial costs of non-communicable diseases to an individual, a local community, a nation or globally?
Cost to health care services such as the NHS for researching and treating
Families may have to move or adapt their home to help a family member
Families’ income may be reduced if the provider has a non-communicable disease. This will impact the entire household and the economy
Explain the effect of lifestyle factors including diet on the incidence of non-communicable diseases at local, national and global levels
A diet high in fat and low in vegetables increases LDL cholesterol. This in turn increases fatty deposits in the arteries and risks for CHD
A diet high in salt can increase blood pressure, increasing risk for cardiovascular diseases
Explain the effect of lifestyle factors including smoking on the incidence of non-communicable diseases at local, national and global levels
Cigarettes contain carcinogens that can result in cancer. Smoking also increases the risk of other lung diseases such as EMPHYSEMA
Smoking while pregnant can harm an unborn baby. This increases the risk of miscarriage and premature birth. Can also increase the risk of a baby having low body mass
Explain the effect of lifestyle factors including alcohol on the incidence of non-communicable diseases at local, national and global levels.
Drinking alcohol or smoking while pregnant increases the risk of foetal alcohol syndrome as smoke contains carbon monoxide so blood carries less oxygen to foetus. Results in these children having learning difficulties and mental/physical issues
Also increases risk of liver cirrhosis and cancer. Also increases the risk of poor cognition, including memory loss and addiction
Explain how the human circulatory system is adapted to supply oxygen to the tissues and remove waste products from tissues
- Double circulatory system which means it has higher blood pressure and a greater flow of blood to the tissues
- Oxygen is carried by RBCs, which contain haemoglobin to bind oxygen
- Arteries carry oxygenated blood to tissues where capillaries deliver oxygen to cells for respiration and energy release
- Capillaries have a large surface area to maximise gas exchange
- Waste products removed such as CO2 which diffuse from cells into the blood plasma
- Blood goes back to the heart in veins which have valves to prevent back flow
Why do the ventricles contract only after the atria contract?
Needs to be time for the ventricle to fill with blood
Otherwise the ventricles will contract while empty
Give two differences in the composition of the blood between blood taken from an artery in the leg and blood taken from a vein in the leg
More oxygen
More glucose
More amino acids
Less carbon dioxide
Less lactic acid
Suggest when artificial hearts are most likely to be used instead of a natural heart donor
Suggest why men and women commonly have different types of cancers
Explain how changes to an obese person’s lifestyle can help them lose weight
[Graph of a possible risk factor with the number of people diagnosed with a disease shown to be a positive correlation]
Evaluate whether the data shows that the factor is a risk factor for the disease
Appears to be a link, but correlation does not indicate causation
More evidence is needed
Could be other factors interacting linked to the disease
Always look at: source of data, period of time, if correlation is constant and the size of the population. Provide a judgement with evaluation questions
Cirrhosis of the liver leads to liver failure
Describe the effects of liver failure on the human body (4)
No bile made in the liver —> Fats not emulsified, so surface area of lipids not increased. pH of small intestine will not be alkaline so enzymes will not work effectively to digest food. As a result, the person may lose weight
Lactic acid not broken down/oxidised —> accumulation of lactic acid in the blood which is toxic. Oxygen debt is prolonged so there will be muscle pain and fatigue
Proteins/amino Acids will not be broken down in the liver. Amino acids not deaminated. Amino acids not made into urea so are accumulated in the blood
Liver will not remove other toxins such as alcohol —> toxins accumulate in the blood so the person may suffer from pain and portal hypertension may occur
Glycogen stores will not be formed —> cannot control blood glucose, so hyperglycaemia may occur
