Topic 7- Run For Your Life Flashcards
(47 cards)
1
Q
What does myogenic mean?
A
The cardiac muscle controls its own pace of contraction without external stimuli. It initiates its own depolarisation and contraction.
2
Q
What is the SAN? (2)
A
- The sinoatrial node is located in the wall of the right atrium
- acts as the pacemaker for the heart, setting the rhythm by sending regular waves of electricity to atrial walls
3
Q
What is the AVN?
A
The atrioventricular node is the only point where impulses can pass through the non-conducting layer.
4
Q
What is the bundle of his?
A
The bundle of his is a group of muscle fibres down the centre of the heart responsible for conducting waves of electrical activity to the purkyne fibres.
5
Q
What are the purkyne fibres?
A
Finer muscle fibres located around the walls of the right and left ventricles.
6
Q
What is the non-conducting layer?
A
It is made from collagen and stops the electrical impulses passing straight from the atria to the ventricles.
7
Q
What are the 5 steps of electrical conduction of the heart?
A
- SAN generates regular waves of electricity which initiate contraction of the heart muscle by sending waves of depolarisation across the atria causing them to contract simultaneously.
- AVN is the only point in the non-conducting layer that impulses can pass. Causes a delay of 0.13 seconds in impulse to ensure the atria have emptied.
- AVN passes wave of depolarisation to the bundle of his.
- Bundle of his conducts the impulses to the apex of the heart.
- The impulses spread up through the purkyne fibres into the muscular walls of the right and left ventricles causing the ventricles to contract simultaneously from the base upwards.
8
Q
What is aerobic respiration and what is the equation?
A
The process where a large amount of energy is released from splitting glucose into CO2 which is lost as a waste product, and hydrogen which combines with atmospheric oxygen to produce water.
C6H12O6+ 6O2= 6H20 + 6CO2 + energy
9
Q
Why is aerobic respiration considered to be a metabolic pathway?
A
Because it uses a series of chemical reactions
10
Q
What is the energy produced from respiration used for?
A
To convert ADP+pi into ATP to provide energy for all the biological processes in the cell.
11
Q
What is each reaction in respiration controlled by?
A
Each reaction in respiration is controlled and catalysed by a specific intracellular enzyme and the enzyme with the slowest activity acts as a rate limiting factor so determines the overall rate of respiration.
12
Q
What are the 3 co enzymes used in respiration and what do they do?
A
- NAD and FAD both transport hydrogen from 1 molecule to another reducing or oxidising it.
- Co enzyme A transports acetate from one molecule to another.
13
Q
Can some organisms use other molecules in respiration?
A
All cells use glucose but some organisms can break down other complex organic molecules like fatty acids or amino acids.
14
Q
What are the 4 stages of aerobic respiration?
A
- Glycolysis
- Link reaction
- Krebs cycle
- Oxidative phosphorylation
15
Q
What is glycolysis and what are the 5 features?
A
Glycolysis is the splitting of a 6C glucose molecule into 2 3C pyruvate molecules.
1. Happens in the cytoplasm
2. Occurs in both aerobic and anaerobic respiration
3. It is the ONLY stage in anaerobic respiration
4. Net gain of 2 ATP
5. Does not need oxygen to take place.
16
Q
What are the 2 phases of glycolysis?
A
- Phosphorylation
- Oxidation
17
Q
What are the 3 steps of stage 1 of glycolysis?
A
- 2 ATP are hydrolysed to donate 2 phosphates/phosphorylate glucose molecule.
- ATP provides the energy to break down the glucose.
- Produces 2 molecules of 3C triose phosphate/ phosphorylated 3C intermediate.
18
Q
What are the 3 steps of stage 2 glycolysis?
A
- The triose phosphate/phosphorylated 3C intermediate is oxidised to form 2 molecules of 3C pyruvate.
- The lost hydrogen ions are collected by co enzyme NAD reducing it to 2 molecules of NADH2
- 4 ADP + 4pi are converted to 4 ATP via condensation reaction but 2 are used to break down glucose so net gain of 2 ATP.
19
Q
What is the equation of glycolysis and draw the diagram?
A
Glucose + 2NAD + 2ADP+2pi = 2 pyruvate + 2NADH + 2ATP
20
Q
What are the 3 features of the link reaction?
A
- The enzymes and co enzymes needed for the reaction are in the mitochondrial matrix
- If oxygen is present pyruvate moves across the double mitochondrial membrane via active transport.
- The reduced NAD are produced in the right place to be used in oxidative phosphorylation in the inner mitochondrial membrane.
21
Q
What are the 4 steps of the Link reaction?
A
- Pyruvate is decarboxylated and loses 1 carbon in the form of CO2.
- Pyruvate is oxidised and loses 1 hydrogen which is collected by the NAD which reduces it into NADH2.
- This converts the pyruvate into acetate due to the loss of the hydrogen
- Acetate combines with co enzyme A to produce 1 molecule of acetyl CoA.
22
Q
How many products are produced from the link reaction for every 1 glucose molecule? (4)
A
Glucose produces 2 pyruvate so the link reaction occurs twice for every 1 glucose.
- 2 molecules of 2C acetyl CoA
- 2 CO2
- 2 NADH2
23
Q
Draw the link reaction .
A
24
Q
Where does the Krebs cycle take place and why?
A
Takes place in the mitochondrial matrix because it has the enzymes and co enzymes needed for the reaction to take place.
25
What are the 5 steps of the Krebs cycle?
1. 2C acetyl co enzyme A combines with 4C oxaloacetate to produce 6C citrate molecule which allows the CoA to be released and reused in the link reaction.
2. The 6C citrate molecule is converted to a 5C compound by decarboxylation 1 carbon is lost as carbon dioxide and it is also dehydrogenated as a hydrogen is removed (oxidised) which is collected by the co enzyme NAD which is reduced to NADH2.
3. 5C compound is converted back to 4C oxaloacetate/ regenerates it as it is again decarboxylated losing 1 carbon as carbon dioxide and dehydrogenated reducing 2NAD and 1 FAD which are then used in oxidative phosphorylation.
4. Substrate level phosphorylation occurs as there is a direct transfer of a phosphate group from an intermediate compound to ADP producing ATP.
26
What is substrate level phosphorylation?
When there is a direct transfer of a phosphate group from an intermediate compound to ADP or another molecule.
27
Draw the Krebs cycle.
28
How many hydrogen ions reduce NAD and FAD?
How many ATP to NAD and FAD make each?
2 hydrogen ions reduce both NAD and FAD as they have different catalysts.
NADH2 produces 3ATP and FADH2 produces 2 ATP
29
What are the 3 steps of anaerobic respiration?
1. Glycolysis converts glucose into 2 molecules of pyruvate.
2. NADH2 transfers a hydrogen ion to pyruvate reducing it to lactate and NAD
3. The NAD can be reused in glycolysis so when there is not much oxygen available, NAD can still be regenerated so a small amount of ATP can be used to provide energy for important biological processes.
30
What happens if too much lactate accumulates? (2)
Cells can tolerate lactate to an extent but when there are excessive amounts, lactate becomes lactic acid.
Lactic acid lowers the pH in muscles.
And it changes the charge of R groups of active sites of glycolysis enzymes which means glycolysis slows/stops.
31
How can lactate be removed? (2)
1. Lactate can be oxidised back to pyruvate and used in the link reaction.
2. Or in liver cells, lactate can be oxidised to pyruvate and then converted to glucose to be used in respiration.
32
What are the 3 adaptations of mitochondria for respiration?
1. The outer membrane is impermeable to hydrogen ions so that:
1. To prevent hydrogen ions from diffusing out of mitochondria/into cytoplasm.
2. To maintain a high concentration of hydrogen ions in the intermembrane space.
3. To allow hydrogen ions to move down the concentration/electrochemcal gradient.
4. By chemiosmosis to synthesise ATP.
2. The inner membrane is folded which is called cristae which increase the surface area allowing more electron transport chain proteins to increase respiration.
3. The intermembrane space is very narrow so that the volume is smaller than the matrix so that even when there aren’t that many hydrogen ions in the intermembrane space, the concentration is still higher because they are more tightly packed in a smaller volume compared to being more spread out in a larger volume which would decreased the concentration.
33
How can you measure the metabolic rate of an animal using a continuous flow respirometer? (5)
1. Use potassium hydroxide/soda lime to remove any CO2 produced.
2. Measure the volume of air entering and leaving the chamber.
3. The decrease in volume of air represents the oxygen taken up by the animal by respiration
4. Control the temperature/ measure the mass of animal/ measure for a stated period of time
5. Calculate the metabolic rate by dividing the volume of oxygen used during a unit of time by the mass of the animal.
34
What are the 4 controls of CP16 investigate the rate of respiration?
1. Concentration/volume of yeast/number of organisms like maggots
2. Same temp is not measuring how temp affects the rate
3. The concentration of sucrose/glucose solution if using yeast
4. PH of the solution.
35
What is the method for CP16 investigating the rate of respiration? (4)
1. Place 5g of maggots into test tube/yeast solution and close the bung.
2. Mark the starting position of the coloured dye on the pipette tube.
3. Record the distance travelled by the coloured dye every minute for 5 minutes, ensuring that the data is collected during the initial rate of reaction before any limiting factors become limiting.
4. Calculate the rate of respiration by dividing the distance travelled by time or calculating the volume of oxygen used by (Pi X R X 2) x distance moved.
36
What is definition of homeostasis and what does it keep the environment in? (2)
Homeostasis is maintaining internal environment within a restricted limit using physiological control systems.
It keeps the internal environment in dynamic equilibrium (which means fluctuating around the optimum)
37
What kind of loop does homeostasis use and what is the definition and how does it work? (3)
Negative feedback loop which acts against a change brining it back to a set point which activate mechanisms including receptors, coordination centres and effectors.
Receptors detecting fluctuating away from the set point and effectors bring about responses to return the level to set point.
38
Why is keeping the internal environment constant through homeostasis and negative feedback loops important? What are the 3 examples?
Vital for cells to function normally and not be damaged.
1. Body temperature
- if core body temperature gets too high (40 degrees) enzyme molecules vibrate too much and break the hydrogen bonds holding them in their 3D shape which means the shape of the active site changes and so they can no longer act as catalysts which reduces the efficiency of metabolic reactions.
2. Glucose concentration in the blood
- all cells need a constant supply of energy to work so the concentration of glucose in the blood must be carefully controlled. Glucose blood concentration usually around 90mg per 100cm3 and pancreas cells monitor this. After exercise, glucose in blood falls as more used in respiration to release energy.
3. Water volume in blood
- Water is essential to keep the body functioning so water volume in blood needs to be kept constant.
- Water is lost by waste products from the body such as urine and sweat so the kidneys have to regulate the water content in the blood.
39
What is the definition of positive feedback loops?
It amplifies a change rather than maintaining homeostasis as a change in the level of a factor causes a response that changes it even further away from original level.
40
What is an example of a positive feedback loop and what are the 3 steps of it?
Hypothermia= when the body temperature lowers too far for normal negative feedback mechanisms to be effective.
1. Body temperature lowers which reduces kinetic energy is enzyme molecules.
2. Enzyme activity reduces which lowers the rate of respiration
3. Less metabolic heat is produced so body temperature lowers even more
41
What are thermoreceptors and where are they found?
Found in the skin and hypothalamus they detect changes in temperature and send impulses down sensory neurones to the hypothalamus
42
What does the hypothalamus contain and what does it do? (3)
The hypothalamus contains the thermoregulatory centre which acts as the co-ordination centre.
It receives impulses from thermoreceptors and sends impulses along motor neurones to effectors.
43
What are the 4 effectors involved in thermoregulation?
1. Erector pili muscles
2. Sweat glands
3. Skeletal muscles
4. Smooth muscle in arterioles
44
What are the 5 steps of the negative feedback loop in thermoregulation when body is too hot? (1) (3) (1) (1) (4)
1. Thermoreceptors send impulses to the hypothalamus and the heat centre
2. Sweat glands secrete more sweat due to increased stimulation by sympathetic neurones from the hypothalamus.
- water has a high latent heat of vaporisation so it takes a lot of energy to break the hydrogen bonds.
- Heat energy from the blood in the capillaries is absorbed by the water and used to break the hydrogen bonds, meaning the water evaporates and heat energy is lost from the body.
3. The thyroid gland releases less thyroxine so that metabolic reactions decrease so less metabolic heat produced.
4. Erector pili muscles relax so that hair on the skin lies flat so that less air is trapped so more heat can be lost more easily as not insulated by the air.
5. Vasodilation:
- smooth muscle in shunt vessels contract so they constrict
- smooth muscle in arterioles relaxes so they dilate
- More blood flows closer to the skins surface so more heat can be lost by radiation
45
46
What are the 6 steps of the negative feedback loop of thermoregulation when body is too cold? (1) (1) (1) (1) (1) (4)
1. Thermoreceptors sends impulses down sensory neurones to the hypothalamus and heat control centre
2. Sweat glands secrete less sweat as they are less stimulated by sympathetic neurones from the hypothalamus
3. Thyroid gland releases my thyroxine and adrenal glands release more adrenaline to increase metabolic reactions to increase heat produced by them
4. Erector pili muscles contract so that the hair on skins surface stands up to trap more air so that less heat is lost by radiation and is insulated by the air as it is a bad conductor of heat.
5. Skeletal muscles contract rapidly by shivering to generate metabolic heat through respiration
6. Vasoconstriction:
- smooth muscles in shunt vessels relax and dilate
- smooth muscles in arterioles contract and constrict
- less blood flows through capillaries closer to skins surface to reduce heat loss.
47
What happens to body temperature during exercise? (1)
Lots of heat is released due to increased rate of respiration so more metabolic heat which increases body temperature.
