Topic 1 Flashcards
Why do only small animals have an open circulatory system?
- Their surface area is small enough to rely on diffusion
- Diffusion is only quick enough in small animals
Because the rate of diffusion is inversely proportional to the distance travelled
What are the advantages of a double circulatory system?
- Blood can pass slowly through the region where gas exchange occurs
- This maximises the transfer of of O2 and CO2
- But this causes a large pressure drop
- Therefore blood is moved back to the heart
- This allows the blood to be pumped around the body at high pressure
- Allowing the organism to be very active
What are the disadvantages of a 3 chambered heart?
- Oxygenated and deoxygenated blood are mixed
Why do animals have a heart and circulation?
- Diffusion is too slow because of a small SA:V ratio
- Which means materials can’t travel quick enough
- So diffusion can’t support a high metabolic rate
- Animals need to maintain a constant temperature (uses energy)
- A heartbeat means blood can reach the capillaries quickly
What is the structure of the heart?
*SEE DIAGRAM
- Shown as if we were facing someone
- Left ventricle has thicker walls because a greater force is needed to push blood around the body
- Tricuspid valve has 3 flaps, preventing back flow into the right atrium
- Bicuspid valve has 2 flaps, preventing back flow into the left atrium
- Atria are smaller as they only have to collect blood
- The Vena Cava and Pulmonary Vein don’t have valves because the Vena Cava has low pressure and the right ventricle also has low pressure, as it has mostly emptied itself
What is intermolecular bonding in water?
- There are strong covalent bonds between H and O
- There are weak intermolecular bonds between each atom
This creates a liquid that can be pumped around the body while carrying materials
What is adhesion?
- The formation of hydrogen bonds between cellulose and water molecules
What is cohesion?
Where hydrogen bonds with water molecules
Why is water a good solvent?
- Water is a good solvent of sonic, charged and polar chemicals
- This is because of the attraction between particles in the chemicals and the polar water molecules (hydrophilic)
- This allows for vital biochemical reactions to occur in the cytoplasm of cells
- This allows substances to be transported around the body, as well as into it
Do non-polar substances dissolve?
- No, as they are hydrophobic
What are the thermal properties of water?
- Water has a high specific heat capacity
- This is because it requires a large volume of energy to break the hydrogen bonds
- This helps to avoid rapid changes in the internal temperature
- This allows organisms to maintain a steady temperature
- Water is at room temperature because the water molecule is polar
What is mass flow?
- The process of materials being carried in a liquid in one direction to multiple exchange surfaces
What is the role of skeletal muscles in blood flow?
- They push blood back up towards the heart
What are the steps of the skeletal muscles assistance in blood flow?
- Relax - The valves are closed
- Contract - The valves open and blood is rushed upwards
- Relax - The valves close as blood falls back
What is the structure and function of the arteries?
- To carry blood away from the heart at high pressure
- They have a tough outer layer to prevent bursting due to high pressure
- They have a thick layer of muscle and elastic fibres to help pump blood through after each contraction of the heart
- They have a narrow lumen to help maintain the high pressure, preventing back flow
What is the structure and function of the capillaries?
- Supplies all cells with their requirements (O2) and removes their waste products (CO2)
- They have a cell wall that is one cell thick - they don’t need a strong wall as most of the blood pressure has been lost
- They have a narrow lumen - it is only just wide enough for a RBC to pass through
The thin walls and narrow lumen bring blood into close contact with body tissues - This close contact means a small diffusion pathway and a large SA
- The walls contain pores which allows WBC to enter/exit
What is the structure and function of veins?
- They return blood to the heart at a low blood pressure
- Their wall is thin and mainly fibrous tissue
- They don’t require a strong wall as pressure has been lost
- They have a wide lumen which means there is less resistance to the blood flow
- They contain valves, which prevent back flow
What is the purpose of the cardiac cycle?
- To flow blood from the vena cava and pulmonary veins to atria
What is the process of Atrial Systole?
- The atria contracts and pumps into ventricles
What is the process of ventricular systole?
- The ventricles contract and pump blood to the arteries
- The increased BP forces atrioventricular valves to shut and semi-lunar valves to open
What is the process of ventricular diastole?
- Everything relaxes and the atria fills with blood
- The increased BP in the atria opens the AV valves
Where does the left ventricle pump blood?
- Thick muscle walls to pump blood around the body
Where does the right ventricle pump blood?
- Thinner muscle walls to pump blood to the lungs
What is atherosclerosis?
- When atheroma’s form inside the arterial walls, thus narrowing the artery
- It increases the chances of blockages in arteries (thrombosis)
- This can lead to a total blockage of coronary arteries = HA
What are causes of Atherosclorosis?
- Damage to endothelium
- Caused by HBP, toxins or oxidised LDL (REF to free radicals)
- Inflammatory response
- WBC leaves blood vessel to artery wall accumulating chemicals from the blood - especially Cholesterol
- Calcium salts and fibrous tissue collects =ing a plaque
- Loss of artery elasticity
- Narrowing can lead to strain and +ve feedback
How does clotting occur at the atheroma?
- Platelets change shape when they come into contact w/ damaged blood vessel
- Stick to exposed collagen in artery wall
- Form a temporary platelet plug =ing more platelets being activated
- Blood contact w/ collagen =ing series of chemical changes
What is the process of atherosclerosis?
- Artery wall damaged so inflammatory response
- WBC enter wall bringing cholesterol which accumulates = Atheroma
- Calcium salts and fibrous tissue accumulate = Plaque
- Wall elasticity reduced and artery narrowed
- Raises BP = Atherosclerosis
- Platelets in contact w/ wall and become sticky
- Platelet plug forms =ing chemical changes
- Prothrombin → Thrombin → Fibrinogen → Fibrin
- Tangled mesh traps blood clots
- A blood clot forms which can lead to myocardial infarction
What are macrophages?
- Make proteins that act in 2 ways
- ‘Punch’ holes in bacteria so that they die
- Phagocytose them (eat them)
- However it can’t deal w/ one particular microorganism as some will always survive
- Also can’t remember past infections
What is correlation?
- When an increase/decrease can be linked to an increase/decrease in the other variable
Does correlation = causation?
NO
Why do people perceive risk wrong?
- People guess the number of deaths per risk wrong mostly b/c:
- Over/underestimate the danger
- Forget about medical advancements
- Over/underestimate the time it takes some illnesses to become fatal
How do you design a good study?
- Large sample size (to make it reliable)
- Use of control variable (to compare against)
- Clearly stated aim and hypothesis
- A design appropriate to the question
- Participants are representative (to make valid results)
- Knowledgeable about what to look for during study and analysing results
- Appropriate measurements are made (to be valid)
- Methods used are repeatable (to be reliable)
- Time scale is suitable
- Other variables taken into account
- Carried out by an unbiased company (to be reliable)
What is a cohort study?
- Follow a group of people over time to see who develops the disease
- People’s exposure to risk factors are recorded and tested for correlation
What is a case-control study?
- A group of people w/ a disease compared w/ a control group
- Information on risk factors is collected
What are monosaccharides?
- Have 2 or more hydroxyl groups
- Either contain an aldehyde group (aldoses)
- Or a ketone group (ketoses)
- Formula = (CHշO)n
- Ring formation
- In aqueous solution aldehyde/ketone groups of a sugar molecule react w/ a hydroxyl group of the same molecule
- Which closes the molecule into a ring
What are Isomers?
- Many monosaccharides differ only in their spatial arrangement
- Small differences = minor changes in chemical properties
- But recognised by enzymes and other proteins = important biological effects
What are dissaccharides?
- Carbon carrying aldehyde/ketone group can react w/ any hydroxyl group
- Disaccharide (2 sugar units) = 2x monosaccharides (2x 1 sugar units)
- Formed through a condensation reaction =ing water being released
- Formula = Cx(HշO)n
What are Oligosaccharides and Polysaccharides?
- Short chains of molecules are called oligosaccharides
- Long chains are called polysaccharides
- Long and linear branched molecules can be made from repeating units
- Oligosaccharides are non-digestible
- Helps feed friendly bacteria so are referred to as prebiotics
- Prebiotics in large intestine
What are α and β links?
- The hydroxyl group can rapidly change
- α hydroxyl group is below
- β hydroxyl group is above
- As soon as one sugar is linked to another the forms are frozen
- (1-4) glycosidic link 1 = carbon no. of first mono, 4 = carbon no. of second
What is starch?
- α glucose arranged in a helix
- Energy stored in plant cells
- Insoluble
- Doesn’t draw water into cells
- Doesn’t easily diffuse into cells
- Compact
- Easily transported when hydrolysed into α-
glucose
What is glycogen?
- Energy stored in animal cells
- Similar storage advantages to starch
- Shorter chains = more highly branched
- Even more readily hydrolysed
What are lipids?
- Insoluble in water
- 3 fatty acids and a glycerol
- Triglyceride = 3 fatty acids and a glycerol
(lipid)
What is the condensation reaction?
- Produces a fat and HշO
- 1st a monoglyceride is formed
- 2nd a diglyceride is formed
- 3rd a triglyceride is formed
- Unsaturated fats are found mainly in plants
- Ester bonds are formed b/w glycerol and
fatty acids
The Energy Balance
- Mass of calories needed each day depends on:
- Volume of energy body uses at rest
(basal metabolic rate)
- Energy used as a result of eating (specific
dynamic action) - The volume of physical activity carried out
- Energy requirement < energy intake = weight
gain - Energy requirement > energy intake = weight
loss - Energy intake = total energy output (heat +
work + energy storage) - RDA = recommended daily intake
- DRV = dietary reference values
- L/HRNI = lower/ higher reference nutrient
intake
What is Cholesterol?
- C27H46O
- w/o cholesterol body couldn’t function
- Help form/repair cell membranes and some
hormones - Links fatty acids together to stabilise and
strengthen cell membranes - Carried by proteins (when together called
lipoproteins)
What are the sources of cholesterol?
- Liver (80%)
- Food (20%)
What are things that affect cholesterol levels?
- Genetics
- Physical activity
- Stress
- Diet/ habits (eg. smoking
What are HDL’s?
- Is good cholesterol
- Unsaturated
- Less likely excess will be deposited on artery
walls - Higher % protein than LDL (more dense)
- Transport cholesterol to liver for elimination
- So ↓blood cholesterol and helps to remove
fatty plaques of atherosclerosis
What are LDL’s?
- Carry cholesterol away from the liver
- Excess can be deposited on artery wall
- So known as bad cholesterol
- Triglyceride + cholesterol + protein = LDL
- Bind w/ receptor sites on cells
- Excess overloads membrane receptors =
↑blood cholesterol - Saturated fats ↓activity of LDL receptors
so LDL not removed from the blood (+ve
feedback)
Fats in the diet
- Saturated = raise blood cholesterol (no double bonds)
- Mono-unsaturated = can ↓cholesterol and improve balance b/w HDL and LDL
- Polyunsaturated = ↑activity of LDL receptor site to actively remove them from blood
Free Radicals
= Any atom/molecule w/ an ‘unpaired’ electron (not a cell)
- Unpaired electron is restored to a pair by pulling a hydrogen atom from another
- Causes damage to DNA, proteins, lipids, cell membranes and mitochondria
- Produced w/n
- Mitochondria in respiration reactions
- Reactions inv. Hydrogen peroxide can = hydroxyl radicals
- The breakdown of toxic chemicals and their products
- WBC and them destroying bacteria and virus infected cells
*. Causes CHD
- LDL’s undergo oxidation b/c of free radicals - released from endothelial cells
- Attracts macrophages and initiates atherosclerosis plaque formation
- Larger no.s of free radicals mean more LDL’s are oxidised
Antioxidants
- Helps reduce levels of free radicals
- Sources inc. tea, red wine, fruit, veg, legumes
- They neutralise free radicals
Vitamin C
- An antioxidant
- Oxidised LDL is more readily taken up by the WBC involved in atherosclerosis
DCPIP Experiment
- DCPIP is a redox dye (blue when oxidised)
- When reduced it turns clear (OIL RIG)
- Vitamin C is ascorbic acid, reduces DCPIP to colourless slightly pink solution
Method:
1. Have 5 test tubes of the same volume of DCPIP→for validity→glass
2. Then use a pipette to place 1 drop of a substance into a test tube→to see if it goes clear→long contact w/ DCPIP = irritation // eyes
3. Keep adding one drop of the substance, till you can’t see the DCPIP, keeping record of how many drops→to see how many drops are necessary→glass // DCPIP
4. Once the DCPIP has disappeared, compare it to a calibration curve of DCPIP volume against vitamin C content→to know vitamin C content
5. Then repeat experiment w/ different substances→to compare
6. Repeat whole experiment and create an average→for reliability
* If its a solid to be tested
- Take a small section and put into a test tube to a depth of ~2cm
- Add a similar volume of distilled water and stir w/ a glass rod
- Leave for a few minutes, and then carry out normal experiment
Effect of Heart Rate in Daphnia
- Daphnia:
- Transparent so can easily see the heart beating
- Counting number of beats may be difficult b/c its quick and their legs
- Freezing them beforehand slows down heart rate
- Or count the rate of leg beats, which is proportional to HR
- Control Group: recording HR of Daphnia in culture solution
- Distilled water may increase HR as less O2
- Blind study may be better so counters don’t assume or bias results
- Problems
- Human error
- difficult to count HR
- making caffeine solutions
- counting for different lengths of time
- Stress on Daphnia may increase HR
- Ethical problems
- Daphnia are living creatures and don’t deserve to be put under stress
- Microscope lights may be hot, so burn Daphnia
- Many Daphnia’s may die as a result of the experiment
- Control variables
- Temperature of the solution
- Size/ age/ gender of the daphnia
- Time spent counting Daphnia
Effect of Heart Rate in Daphnia - Method
- Place a few strands of cotton wool on a cavity slide→restrict flea movement→glass
- Using a pipette transfer the Daphnia, and add pond water to the slide→for normal breathing rate→glass // water
- Use as much water as possible, to keep O2 levels high
- Use a stopwatch and count the no. of heart beats in 10 seconds→to record heart rate
- Repeat procedure using other Daphnia, and create an average→for validity
- Repeat previous steps using different caffeine solutions→for reliability
- Record results in a suitable format and present them in an appropriate graph→for validity and reliability
What are the habits that can increase risk of CVD?
- Smoking
- Caffeine
- Cholesterol levels (esp. LDL cholesterol)
What can reduce risk of CVD?
- Scientific Knowledge of:
- Diet
- Obesity indicators
- BMI
- Waist-to-hip ratio
- Exercise
- Smoking
Diuretics
- Increase urine volume
- Rids body of excess fluids and salts
- Blood volume falls
- Lower stroke volume
- BP drops
Beta Blockers
- Blocks the response the heart gives to hormones, eg. adrenaline
- Contractions less strong = lowered HR and BP
Diuretics and Beta Blockers - Side Effects
- General: prolonged BP = dizziness = falls/ injuries
- Which can be life threatening in elderly
- Specific: dry cough, abnormal heart rhythms, fatigue, swelling of ankles, constipation, impotence
- They can mask benefits and lead to patients dropping treatment
Diuretics and Beta Blockers - Benefits
- They lower BP
- Means ↓ risk of CVD, which inc. life threatening conditions (eg. heart attack)
Statins
- What it does:
- Inhibits cholesterol synthesis in the liver
- Increases LDL uptake
- Improves the balance of HDL:LDL
- Improves the lining of the endothelium
Statins - Side Effects
- Muscle pain, constipation, nausea and changes in attitude
Anticoagulant and Platelet inhibitory drugs
- Prevents blood clotting easily
- Prescribed after surgery from thrombosis
- Anticoagulants, eg. Warfarin
- Interfered w/ manufacture of prothrombin
- Platelet inhibitors, eg. Aspirin
- Make platelets less sticky
- Reduces blood clotting
Anticoagulant and Platelet inhibitory drugs - Risks
- Aspirin = irritates stomach lining, can cause bleeding
- Careful monitoring of any drug is needed to prevent internal bleeding, eg. in the brain
