Topic 1 - Lifestyle, Health and Risk Flashcards
What is an open circulatory system?
One where blood is not contained in closed blood vessels
What is a closed circulatory system?
One where blood is contained within blood vessels
Why do larger organisms require a mass transport system?
Their SA:vol ratio is much smaller and therefore diffusion cannot be effective. A transport system is used to facilitate mass flow of substances (heart and circulatory system)
What is mass transport?
The bulk movement of liquids/gases in one direction
What is mass flow?
The movement of fluid down a pressure gradient
What does mass transport help to do?
- maintain diffusion gradients
- ensure effective cell activity
- bring substances quickly
What properties does water have that make it cohesive and a solvent?
Water has unevenly shared electrons in a covalent bond, creating a dipole - this means that hydrogen bonds can form between the negative and positive dipoles of water molecules
What is cohesion and adhesion and why is it important that water has these 2 properties in transport?
Cohesion - attraction of water molecules to each other
Adhesion - attraction of water molecules to other molecules
This means that water flows easily
How is water a solvent and why is this important in transport?
Water molecules can surround charged particles and cause them to break up
This dissolves them for efficient transport
What is a single circulatory system?
A simple loop in which blood flows
What is a double circulatory system?
Where the blood passes through the heart twice for each complete circuit of the body
What are the features of arteries?
Narrow lumen, thicker walls, more collagen, smooth muscles and elastic fibres, no valves
How does the structure of arteries relate to their function?
Elastic fibres for elastic recoil to maintain pressure, smooth muscle to contract, narrow lumen to maintain high blood pressure, collagen to avoid rupture/damage, smooth endothelial wall to reduce friction
What are the features of veins?
Wide lumen, thinner walls, less collagen and smooth muscle, fewer elastic fibres, valves
How does the structure of veins relate to their function?
Little elastic fibres/muscle as blood is under lower pressure, wider lumen due to low pressure, valves prevent the backflow of blood, body muscles around veins contract to move blood
What are the features of capillaries?
No muscle, wall made of 1 cell thick endothelium, small lumen, no valves
How does the structure of capillaries relate to their function?
One cell thick to reduce diffusion distance, narrow lumen (one cell wide) to force red blood cells to slow down for diffusion
Why do double circulatory systems enable mammals to carry out effective gas exchange?
- One side of heart pumps blood to lungs, the other to the body
- separation of oxygenated and deoxygenated blood
- maintained concentration gradient
- transport system for mass flow, supplying O2 to cells
- need a good supply of oxygen as mammals are very active
What is the cardiac cycle?
The series of events that take place within one heartbeat
What happens to pressure when volume increases/decreases within a chamber of the heart?
Volume increase = pressure decrease
Volume decrease = pressure increase
When do valves open/close in the heart?
Valves open when the pressure of the blood behind them is greater than the pressure in front of them
Valves close when the pressure behind them is less than the pressure in front of them
What happens during atrial systole?
Atria contract (volume decrease, pressure increase) Atrioventricular valves forced open Blood forced into ventricles
What happens during ventricular systole?
The ventricles contract (volume decrease, pressure increase)
AV valves shut, semi-lunar valves open
Blood forces into arteries and out of heart
What happens during diastole?
Atria and ventricles relax
Atria continue to fill with blood
Blood flows passively into the ventricles
How do pressure differences in the heart ensure efficient pumping of the blood into the arteries?
- greater pressure in ventricles than atria
- this causes AV valves to shut
- the semi lunar valves are then forced open and blood is pushed into arteries
Why is there a difference in thickness between the right atrium wall and right ventricle wall?
The right atrium wall is thinner because of the higher blood pressure required in the ventricles. The right atrium only pumps blood to the ventricle but the ventricle pumps blood to the lungs (pulmonary artery)
Why is the left ventricle wall thicker than the right ventricle wall?
It has to pump blood further around the body, and therefore has to withstand higher pressure
What is atherosclerosis?
The hardening of the arteries due to damage of the endothelium of an artery
How does atherosclerosis develop?
Endothelial layer of artery is damaged, this leads to an inflammatory response from WBCS.
The WBCs entering leads to other chemicals gathering, mainly cholesterol which accumulates to form an atheroma.
Calcium salts and fibrous tissue build up the deposit and a hard plaque forms. The artery narrows, blood pressure rises and a positive feedback loop is established.
What is the consequence of atherosclerosis on an artery?
Reduced elasticity, increased blood pressure due to abnormal/reduced blood flow
What happens in the clotting cascade?
Damaged blood vessel releases protein thromboplastin. Calcium ions from plasma and thromboplastin trigger conversion of soluble promthrombin protein into enzyme thrombin.
Thrombin catalyses conversion of soluble protein fibrinogen to insoluble protein fibrin. Fibrin fibres mesh and tangle together, trapping platelets and RBCs - a blood clot is formed.
How can atheromas increase the risk of blood clotting?
The plaque deposit from atheromas can rupture through the endothelium, triggering thrombosis
What can blood clotting lead to?
Heart attacks
Strokes
How does blood clotting lead to heart attacks?
Atheromas and blood clots in coronary arteries restrict blood flow to areas of the heart. This means the cardiac cells receive less oxygen and the cells cannot produce ATP or perform respiration, meaning they may die.
This leads to a heart attack, which may be fatal
How can the location of an atheroma result in the position and size of dead heart muscle?
Area of dead heart muscle is the region normally supplied by the blocked artery. The artery normally provides the cells with glucose/oxygen, so the cells will be unable to respire and therefore die.
If the atheroma is located near the end of an artery, a much smaller region will be impacted.
How can a blood clot in an artery leading to the brain cause a stroke?
Reduced blood flow due to clot means oxygen/glucose will not reach cells in brain. Therefore there is no aerobic respiration and no ATP produced. The brain needs lots of ATP to function, so lactic acid is produced from anaerobic respiration which inhibits enzymes and is toxic
What is a platelet?
A cell fragment that releases thromboplastin
What is fibrinogen?
A soluble plasma protein
What is cardiovascular disease?
A general term for conditions affecting the heart and blood vessels. It is usually associated with atherosclerosis and thrombosis
What are risk factors?
Factors leading to an increased chance of disease
What are the lifestyle factors linked to CVD?
Diet - high in saturated fat increases blood cholesterol levels, high salt = high blood pressure
High blood pressure - linked to stress, poor diet, alcohol and inactivity, high BP increases risk of damage to artery walls
Smoking - CO reduces oxygen carrying capacity of haemoglobin (strokes, heart attack), nicotine increases risk of thrombosis, smoking decreases level of antioxidants
What are other factors linked to risk of CVD?
Genetics - inherit high BP or high cholesterol
Age - plaque builds up over time
Biological sex - men more likely than women (oestrogen increases HDL)
What are factors that will increase the risk of CVD?
- obesity
- high blood pressure
- high blood cholesterol
- smoking
- diet high in saturated fats
What is correlation?
When a change in one variable is accompanied by a change in another
What is causation?
When a change in one variable is caused by a change in another
What is risk?
The chance/probability a harmful event will occur
What are the reasons that risk can be overestimated?
- misleading info in media
- overexposure to information
- personal experience
- event causing severe harm
What are the reasons that risk can be underestimated?
- lack of information
- misunderstanding of factors leading to disease
- harm being non-immediate
- unfamiliarity with the event
What factors must be considered when evaluating experimental design?
- sample size
- variables
- data
- controls
- repetition
- reproducibility
How can it be concluded from a study that a factor is a health risk?
One study is not enough to conclude this. Similar studies can be carried out to investigate the link, but sometimes they may come up with conflicting evidence
What are the types of medication used to treat CVD?
- statins
- anticoagulants
- platelet inhibitors
- antihypertensives
How do antihypertensives work, and what are the 3 main types?
Antihypertensives lower blood pressure to reduce risk of arterial endothelial damage
Beta Blockers = prevent increase in heart rate
Vasodilators = increase diameter of blood vessels
Diuretics = decrease sodium reabsorbed into blood by kidneys, therefore decreasing the volume of water being reabsorbed
How do anticoagulants work?
Reduce blood clotting to decrease likelihood of thrombosis and blood vessels being blocked by clots (blocking synthesis of clotting factors and release of Vit K)
How do statins work?
Lower blood cholesterol levels by blocking an enzyme in the liver. This lowers LDL concentration in blood and reduces the risk of atheroma formation
How do platelet inhibitors work?
Reduce blood clotting by preventing the clumping together of clots - prevent platelets from becoming activated/sticky to prevent formation of blood clot
What are the benefits and risk of statins?
BENEFITS: reduce levels of LDLs so reduce atheroma development, increase levels of HDLs
RISKS: can take a while to be effective, must be taken long term, side effects include muscle and joint pain, liver damage and neurological issues, gives patients a false sense of security
What are the benefits and risks of anti-hypertensives?
BENEFITS: reduce blood pressure, which can be monitored at home
RISKS: side effects include headaches, drowsiness, heart palpitations, patients may stop taking medicines due to the side effects
What are the benefits and risks of anticoagulants?
BENEFITS: reduce formation of blood clots, and reduce size and growth of existing blood clots
RISKS: can cause excessive bleeding if injury occurs, side effects include osteoporosis and fainting, can damage foetus
What are the benefits and risks of platelet inhbitors?
BENEFITS: reduces formation of new blood clots
RISKS: can cause excessive bleeding if injury occurs, side effects include rashes, liver dysfunction and stomach lining damage
What is an energy budget?
The amount of energy taken in by an organism minus the amount of energy the organism transfers during life processes
What is the equation for an energy budget?
energy input - energy output = energy budget
Why should energy budgets be balanced?
If energy intake is higher than the energy output excess energy will be converted into fats by the body so the person will gain weight
If energy intake is less than energy output the body will need to take energy from elsewhere and fat reserves will be converted into energy, the person will lose weight
What are carbohydrates?
Carbohydrates are biological macromolecules made up of smaller molecules called monomers, including only C, O and H atoms
What are monosaccharides?
The monomers of carbohydrates, sugars formed from molecules with varying numbers of C atoms
General formula = (CH2O)n, where n is the number of carbon atoms in the molecule
What is the function of monosaccharides?
To store energy within their bonds, so when broken during respiration, energy is released
They are rapidly absorbed and require little, or in the case of glucose, no change before being used in cellular respiration
What are some examples of monosaccharides?
Glucose, galactose, fructose
What is a glycosidic bond?
A bond formed when 2 hydroxyl (OH) groups on different monosaccharides interact to form a strong covalent glycosidic bond. Formed via condensation reaction
How can glycosidic bonds be broken?
Via hydrolysis, the addition of a H2O molecule across the bond
What are disaccharides?
Molecules formed when 2 monosaccharides join together via a condensation reaction, held together by a glycosidic bond
What is the function of disaccharides?
To provide the body with a quick release source of energy as they are easily broken down by enzymes and absorbed into the bloodstream
What are some examples of common disaccharides?
Sucrose (glucose and fructose) 1,2 glycosidic
Maltose (two glucose) 1,4 glycosidic
Lactose (glucose and galactose) 1,4 glycosidic
Why does eating complex carbohydrates not cause the swings in blood sugar seen after eating monosaccharides?
Complex carbohydrates (polysaccharides and disaccharides) have to be digested into monosaccharides before being absorbed, which takes some time
What are polysaccharides?
Carbohydrate polymers: repeated chains of many monosaccharides joined by glycosidic bonds
What are the 3 main types of polysaccharide found in foods?
Starch and cellulose in plants, glycogen in animals
What 2 molecules is starch made up of?
Amylose and amylopectin
What is the structure of amylose? How does this relate to it’s function?
Straight unbranched chain of alpha glucose, 1,4 glycosidic bonds only, causing chain to coil into a spiral helix shape
Spural shape means it is more compact for storage
What is the structure of amylopectin? How does this relate to it’s function?
Branched structure due to some 1,6 glycosidic bonds, also has 1,4 glycosidic bonds between alpha glucose molecules
Branches means it can be rapidly hydrolysed for use during cellular respiration
Why are starch and glycogen good storage molecules?
Compact spiral structure and insoluble nature means they are excellent storage molecules. Do not diffuse across cell membranes and have very little osmotic effect within the cell
Why does glycogen give easy access to stored energy?
It has numerous side branches, meaning it can be rapidly hydrolysed to give access to it’s energy
What is the structure of glycogen? How does this relate to it’s function?
Highly branched but not coiled, made up of 1,4 and 1,6 glycosidic bonds
More branched than amylopectin, providing more terminal glucose molecules which can either be added to or removed by RAPID hydrolysis (quick storage/release of glucose)
What are lipids?
Macromolecules that contain carbon, hydrogen and oxygen. Unlike carbohydrates they contain a lower proportion of oxygen
What are the roles and properties of lipids?
ROLES = energy yield, energy storage, insulation and hormonal communication PROPERTIES = non polar and hydrophobic
What monomers form triglycerides?
Glycerol
Fatty acids
What is a triglyceride?
Triglycerides are made up of 3 fatty acids and one glycerol molecule linked by condensation reactions
What bond links each fatty acid and the glycerol?
Ester bond
What are the properties of saturated fatty acids?
They have no double bonds in the hydrocarbon tail, straight (unbranched, linear) chains, ability to pack together tightly, strong intermolecular forces, SOLID at room temp due to high melting point
What are the properties of unsaturated fatty acids?
Have one or more C=C double bond in hydrocarbon tail, kinked structure therefore cannot pack together tightly, weaker intermolecular forces, LIQUID at room temp due to low melting point
What is the difference between monounsaturated fats and polyunsaturated fats?
Monounsaturated fats have one C=C double bond, polyunsaturated fats have 2 or more
How can unsaturated fats be made more solid at room temp?
Adding hydrogen to the bonds, making them saturated (hydrogenation)
What is the difference between cis-fatty acids and trans-fatty acids?
Cis-fatty = H atoms on same side of double bond, can be metabolised by enzymes
Trans-fatty = H atoms on opposite side of double bond, are not metabolised
What is cholesterol, and what do cells require it for?
A short lipid molecule produced in the liver
Required for: cell membrane functioning, sex hormone structure, synthesis of bile
What are HDLs?
High density lipoproteins (GOOD CHOLESTEROL)
Contain unsaturated fat, cholesterol and protein
Their role is to transport cholesterol from body tissues to the liver where it is excreted
Reduce blood cholesterol levels when too high and are thought to contribute to the removal of cholesterol from fatty plaques
What are LDLs?
Low density lipoproteins (BAD CHOLESTEROL)
Contain saturated fat, cholesterol and protein
Their role is to move cholesterol from the liver into the bloodstream where it remains until required by cells
They increase blood cholesterol levels when too low, and bind to receptors so they can be taken up by cells
High levels can lead to receptor blockages, creating high blood cholesterol
How can you reduce risk factors of CVD?
Diet - decrease proportion of saturated fats
Obesity - lifestyle choices to reduce weight to healthy range
Smoking - health warnings on cigarette packages, TV and media portray as unhealthy lifestyle choice
Exercise - increased hours of PE at school, targeted encouragement to reduce inactivity
How is obesity measured?
BMI
Waist to Hip ratio
What is BMI?
BMI = body mass index
a conventionally used method of classifying body weight relative to a person’s height
BMI = body mass in kg/height in m ^2
What is waist to hip ratio?
Ratio of waist size to hip size
Found by dividing waist circumference by hip circumference
Which type of lipoprotein is associated with atherosclerosis?
LDLs
They create high blood cholesterol levels, which can be deposited in artery walls, forming atheromas
What factors should be taken into consideration when analysing data from studies on health risk factors?
- sample size
- individuals in the sample
- control group
- statistical significance
- influence of other variables
What is a causal relationship?
Where a change in one variable directly causes a change in another
