Topic 7 - Run for your life Flashcards
1
Q
What does effective movement of the human body require?
A
Both muscle and an incompressible skeleton
2
Q
What are tendons?
A
Lengths of strong connective tissue connecting muscles to bones
3
Q
What are ligaments?
A
Lengths of strong connective tissue connecting bones to other bones
4
Q
What are more elastic, ligaments or tendons?
A
Ligaments are more elastic as tendons do not stretch
5
Q
What is antagonistic muscle action?
A
When one muscle pulls in one direction at a joint and the other muscle pulls in the opposite direction
6
Q
What is an extensor muscle?
A
A muscle that straightens a joint during contraction
7
Q
What is a flexor muscle?
A
A muscle that bends a joint during contraction
8
Q
How do the tricep and bicep work together as an antagonistic muscle pair?
A
TO RAISE LOWER ARM: bicep contracts, tricep relaxes. Pulls bone so arm flexes around the joint
TO LOWER LOWER ARM: tricep contracts and bicep relaxes. Pulls bone so arm straightens at elbow
9
Q
What is skeletal muscle?
A
Muscles in the body that are attached to the skeleton
10
Q
How is muscle fibre highly specialised?
A
- each fibre contains an organised arrangement of contractile proteins in cytoplasm
- each fibre is surrounded by a cell surface membrane (sarcolemma)
- each fibre contains many nuclei (multi nucleated)
11
Q
What is the cytoplasm, cell surface membrane and endoplasmic reticulum called in a muscle fibre?
A
Sarcoplasm
Sarcolemma
Sarcoplasmic reticulum
12
Q
What are T tubules?
A
Deep tube like projections that fold in from outer surface of sarcolemma. Run close to SR and help spread electrical impulses throughout muscle fibre
13
Q
What are myofibrils?
A
Long cylindrical organelles inside muscle fibres which are bundles of actin and myosin filaments
14
Q
How are actin and myosin filaments organised in myofibrils?
A
H band - only thick myosin filaments present
I band - only thin actin filaments present
A band - areas where only myosin present and myosin and actin overlap
M line - attachment for myosin filaments
Z line - attachment for actin filaments
15
Q
What is a sarcomere?
A
Short repeating units of myofibril (between two Z lines)
16
Q
How is the structure of a muscle fibre related to its function?
A
Many mitochondria to supply ATP via aerobic respiration
Sarcolemma contains voltage gated channels to allow depolarisation of muscle fibre
Presence of myofibrils to allow contraction of muscle
17
Q
What are the two types of muscle fibres found in muscle?
A
Fast twitch fibres
Slow twitch fibres
18
Q
What are fast twitch muscle fibres?
A
Muscle fibres that contract rapidly, with a rapid contraction-relaxation cycle.
Myosin heads bind and unbind 5 times quicker than slow twitch.
Rely on anaerobic respiration for ATP, and are suited to short bursts of high intensity activity as they fatigue quickly.
19
Q
What are slow twitch muscle fibres?
A
Muscle fibres that contract more slowly.
Rely on aerobic respiration for ATP and fatigue less quickly, making them suited to endurance
20
Q
What are the differences between fast twitch and slow twitch muscle fibres?
A
Fast twitch = anaerobic for ATP (tire quicker), slow twitch = aerobic for ATP (endurance)
Fast twitch have fewer capillaries and low amounts of myoglobin meaning they appear pale in colour, whereas slow twitch have a denser network of capillaries and high amounts of myoglobin, haemoglobin and mitochondria so appear dark red
21
Q
What are some examples of slow and fast twitch muscle fibres?
A
Slow = muscles used for posture (e.g. back)
Fast = limbs of animals, human eyelids
22
Q
What is myoglobin?
A
A red pigment molecule that functions as a store of oxygen in muscles and increases the rate of oxygen absorption from capillaries
23
Q
What is the structure of the thick filaments of muscle fibres?
A
Made up of myosin molecules which are fibrous protein molecules with a globular head.
In the thick filament, many myosin molecules lie next to each other which their globular heads all pointing away from M line
24
Q
What is the structure of the thin filaments of muscle fibres?
A
Many actin molecules link together to form a chain, and two actin chains twist together to form one thin filament. A fibrous protein known as tropomyosin is twisted around the 2 chains. Another protein known as troponin is attached to the actin chains at regular intervals.
25
How do muscle fibres contract?
- action potential at neuromuscular junction causes calcium ions to be released from sarcoplasmic reticulum
- calcium ions bind to troponin molecules, making them change shape and moving tropomyosin to expose myosin binding sites on actin
- myosin heads now bind to binding sites, forming cross bridges
- the myosin head bends/nods, pulling the actin filaments over the myosin, ATP is hydrolysed, releasing ADP and Pi
- ATP binds to myosin heads causing them to detach and they move back to original position. Process then repeats/stop
26
How is concentration of calcium ions around a myofibril controlled?
Calcium ions are released from the sarcoplasmic reticulum in response to nerve impulse.
Calcium channels open to allow ions to cross membrane and enter sarcoplasm
Calcium ions are taken back into the SR via active transport
27
How does the sequence of events of muscle contraction explain rigor mortis?
There is no ATP after death to detach myosin heads, so the muscles remain contracted
28
How do athletes with transtibial amputations move their prosthetic limbs during a race?
Their muscles are still attached to bones in lower leg, and the prosthetic is attached to the lower leg so also moves
29
What is aerobic respiration?
The process of breaking down a respiratory substrate in order to produce ATP using oxygen
30
What is the equation for aerobic respiration?
glucose + oxygen → carbon dioxide + water + energy
C6H12O6 + 6O2 → 6CO2 + 6H2O
31
What is the energy released from respiration used to do?
Phosphorylate ADP to form ATP
32
What are the four stages of aerobic respiration?
- Glycolysis
- the Link reaction
- the Krebs cycle
- Oxidative phosphorylation
33
What is the overall rate of aerobic respiration determined by?
Enzymes at each stage - whichever catalyses the reaction the slowest
34
What is the structure of mitochondria?
Two phospholipid membranes. Inner membrane is folded to form cristae - where ATP synthase enzymes are located. Intermembrane space is where concentration gradient accumulates for oxidative phosphorylation. Matrix is the 'cytoplasm', contains ribosomes, enzymes and circular mitochondrial DNA
35
How does the structure of a mitochondria relate to it's function?
Outer membrane - smooth and permeable to several small molecules
Inner membrane - folded (greater SA), less permeable, site of ETC and ATP synthase
Intermembrane space - maintains conc gradient
Matrix - contains enzymes for respiration
36
Where does each stage of respiration take place?
Glycolysis - cell cytoplasm
Link reaction - matrix
Krebs cycle - matrix
Oxidative phosphorylation - inner membrane of mitochondria
37
What are the products of glycolysis?
2 pyruvate molecules (3C)
Net gain of 2 ATP
2 reduced NAD
38
What happens in glycolysis?
Phosphorylation of glucose,
- produces 2 molecules of triose phosphate
- 2 ATP required, producing 2 ADP molecules
Oxidation of triose phosphate
- Triose phosphate oxidised to pyruvate, loses 2 H+ ions
- H+ ions collected by NAD to form 2 reduced NAD
- 4 ADP → 4 ATP
39
What is the net gain of ATP in glycolysis
2 (2 in, 4 out)
40
How does pyruvate enter the matrix?
Moves across double membrane of mitochondria via active transport, requiring a transport protein and small amount of ATP
41
What are the products of the Link reaction?
2 molecules of Acetyl coA, 2 CO2, 2 molecules of reduced NAD
(2 because 2 pyruvate go in)
42
What happens in the Link reaction?
- Pyruvate oxidised (dehydrogenated) to produce acetate
- Pyruvate also decarboxylated, carbon removed to form CO2
- NAD reduced to reduced NAD (collects H from pyruvate)
- Acetate combines with coenzyme A to form acetyl coenzyme A
43
What are the products of the Krebs cycle?
2 pyruvate produced in glycolysis so Krebs cycle will turn twice
Therefore at the end of 2 turns of Krebs:
- 2 ATP
- 6 NADH (reduced NAD)
- 2 FADH2 (reduced FAD)
- 4 CO2
44
What happens in the Krebs cycle?
- 2C Acetyl CoA enters circular pathway
- 4C oxaloacetate accepts 2C acetyl fragment to form 6C citrate. CoA released to be reused in link reaction
- Citrate decarboxylated (CO2 released) and dehydrogenated (NAD→NADH) to form intermediate 5C
- 5C decarboxylated (CO2 released) and dehydrogenated x3 (forming 2 NADH and 1 FADH2) and dephosphorylated (ADP to ATP) to regenerated oxaloacetate
45
What happens in oxidative phosphorylation?
- H atoms donated by reduced NAD and reduced FAD from Krebs cycle
- split into protons and electrons
- electrons move down electron transport chain and release energy which is then used to transport protons from matrix into intermembrane space
- this establishes a concentration gradient of protons
- protons return to matrix via facilitated diffused via channel protein ATP synthase
- this provides energy for ATP synthesis
- oxygen acts as final electron acceptor, combining with protons and electrons to form water
46
What is the role of carrier molecules in the electron transport chain?
Carrier molecules receive H atoms from red NAD and FAD, which they split into e- and H+. Electrons are transferred via a series of redox reactions, and the energy released is used to pump H+ ions into the intermembrane space
47
How many ATP molecules are produced from each red NAD/FAD?
3 ATP molecules for every reduced NAD
2 ATP molecules for every reduced FAD
48
How many molecules of ATP can be produced per molecule of glucose (breakdown)?
2 ATP in glycolysis
2 ATP in Krebs cycle
30 by reduced NAD in OP and 4 by reduced FAD in OP
Total = 38 ATP
49
How many red NAD and red FAD are produced at each stage of respiration and can therefore go on to produce ATP?
Glycolysis = 2 red NAD
Link reaction = 2 red NAD
Krebs cycle = 6 red NAD, 2 red FAD
Total = 10 red NAD, 2 red FAD
50
Why is the total ATP produced from one glucose molecule only theoretically 38?
Have to invest energy in active transport so the actual total is about 32 ATP
51
Why is oxygen so important for aerobic respiration?
It acts as the final electron acceptor.
Without it, the ETC cannot continue as electrons have nowhere to go, and reduced coenzymes NADH and FADH2 cannot be oxidised to regenerate NAD and FAD so cannot be used in further hydrogen transport
52
What is the equation for the reaction of electrons and protons with oxygen at the end of oxidative phosphorylation?
2H+ + 1/2 O2 → H2O
53
What are the consequences if no oxygen is available in respiration?
- no final acceptor of electrons from ETC
- ETC stops functioning
- no more ATP produced via ox phosp
- red NAD and FAD aren't oxidised by an electron carrier
- no oxidised NAD and FAD available for dehydrogenation in Krebs
- Krebs cycle stops
- Link reaction stops
54
Why does reduced NAD and FAD need to be oxidised in a mitochondrion?
So H can be delivered to ETC to allow ATP synthesis, to regenerate NAD
55
What are the 2 different anaerobic pathways?
- lactate pathway in animals
- ethanol pathway in yeast
56
What happens in the lactate pathway of anaerobic respiration?
- red NAD transfers hydrogen to pyruvate to form lactate
- this means NAD can now be reused in glycolysis
- pyruvate is the hydrogen acceptor
- lactate can be further metabolised and a small amount of ATP is produced (from conversion of glucose to
57
What happens to lactate after it is produced?
2 things can happen
- can be oxidised back to pyruvate which is then channelled into Krebs
- can be converted into glucose by liver cells for use during respiration or for storage (glycogen)
58
Why do animals breathe deeper and faster after exercise?
Oxidation of lactate back to pyruvate requires extra oxygen. This is referred to as oxygen debt!
59
What is a respirometer?
A piece of equipment used to measure and investigate the rate of oxygen consumption during aerobic respiration in organisms
60
What is homeostasis?
Maintenance of a constant internal environment at dynamic equilibrium within an optimum range/narrow limits despite changes in the external environment
61
Why is homeostasis of temperature important?
Ensures the maintenance of optimal conditions for enzyme action and cell function.
Increase in temperature = denature enzymes (kinetic energy causes breakage of named bonds in tertiary structure, changes active site, enzyme-substrate complex cannot form)
62
Why is homeostasis of blood glucose important, where is it regulated?
Cells need a constant supply of energy in the form of ATP - glucose is respired to supply this ATP
Cells in pancreas monitor blood glucose concentrations
63
Why is homeostasis of water in the body important, where is it regulated?
Essential requirement for cells to function optimally - makes up cell cytoplasm and takes part in metabolic reactions
Kidneys regulate amount of water in the blood
64
What is thermoregulation?
Maintenance of constant internal body temperature
65
How are thermoregulatory responses generated?
Thermoreceptors in hypothalamus/skin detect changes in temperature, thermoregulatory centre in the hypothalamus is stimulated. This sends impulses to sweat glands etc, changing metabolic rate
66
What are the body's cooling mechanisms?
Vasodilation of blood vessels supplying skin capillaries - muscles in arterioles relax, allowing skin to dilate and more blood to flow through skin capillaries (heat lost to environment via radiation)
Sweating - sweat secreted by sweat glands cools skin via evaporation
Flatting of hairs - stops hairs from forming an insulation layer of trapped air, allowing heat to leave
67
What are the body's warming mechanisms?
Vasoconstriction of blood vessels supplying skin capillaries - arteriole muscles contract to allow less blood flow so less heat loss
Boosting metabolic rate - e.g. release of adrenaline or thyroxine increases heat production as most metabolic reactions are exothermic
Shivering - reflex action causing muscles to contract rapidly and regularly, metabolic reactions powering this generates heat
Erection of hairs - hair erector pili muscles contract, causing hairs to stand on end and create an insulating layer
Less sweating - sweat glands secrete less sweat, reducing heat loss via evaporation
68
How does the hypothalamus help to regulate body temperature?
- detection via thermoreceptors
- monitors temperature of blood
- initiates homeostatic responses via motor neurons to effectors (physiological response)
69
What is negative feedback?
Feedback loop that reduces/reverses the effect of an original stimulus/change in order to keep a factor within a normal range
e.g. temperature control
70
What is positive feedback?
Feedback loop where the stimulus produces a response causing factor/change to deviate even more from the normal range
e.g. oxytocin during labour
71
How can hormones alter events inside a cell?
Via the influence of gene expression
Eukaryotes use transcription factors to control gene expression
72
How do steroid hormones cause changes inside a cell?
Steroid hormones = lipid soluble, can pass through phospholipid bilayer
Enter the cell and bind to transcription factors in the nucleus, acting directly as a transcriptional regulator by allowing RNA polymerase to bind and increase the rate of expression
73
How do protein and peptide hormones cause changes inside a cell?
Protein/peptide hormones are lipid insoluble so cannot cross the cell membrane
They bind to receptors in the cell surface membrane, which activates second messengers within the cell (e.g. cyclic AMP). Activated second messenger activate enzymes called protein kinases, triggering a cascade (chain of reactions) which lead to changes in activity of transcription factors to affect gene expression.
74
What does myogenic mean?
Cardiac muscle which can initiate its own contractions/depolarisation without the need for nervous stimulation/external stimuli
75
How does electrical activity in the heart stimulate the contraction of atria/ventricles?
1. cells at sinoatrial node become depolarised, initiating a wave of excitation which spreads over atria and causes them to contract
2. non conducting septum tissue prevents wave of excitation passing to ventricles
3. instead, depolarisation carried to atrioventricular node, which is stimulated after a slight delay
4. stimulation passed along the bundle of His, which divides into 2 conducting fibres called the Purkyne tissue
5. purkyne fibres initiate wave of excitation/depolarisation from the apex of the heart upwards, causing ventricles to contract
76
What is an ECG, how is it produced?
An electrocardiogram - shows number of distinctive electrical waves produced by the activity of the heart
Electrodes placed on skin surrounding heart and voltage measured
77
What is the P wave on an ECG, what is it caused by?
Initial wave on ECG, caused by the depolarisation of atria (atrial systole)
78
What is the QRS complex on an ECG, what is it caused by?
Large peak on ECG, caused by depolarisation of ventricles (ventricular systole) - largest wave as ventricles have largest muscular mass
79
What is the T wave on an ECG, what is it caused by?
Small wave after QRS complex, caused by repolarisation of ventricles (ventricular diastole)
80
What are some of the common heart problems that can be diagnosed by ECGs?
Tachycardia - heart beats too fast
Bradycardia - heart beats too slow
Ectopic heartbeat - early heartbeat followed by a pause
Fibrillation - an irregular heartbeat rhythym
81
What are the patterns on an ECG that show the common heart problems?
Tachycardia - peaks too close
Bradycardia - peaks too far apart
Ectopic heartbeat - beat comes too early and followed by a pause
Fibrillation - irregularity, rhythm is lost
82
How can fibrillation be fatal?
Once atria and ventricles stop contracting properly, they will not go back to their regular pattern without electrical shock (defibrillation)
83
What is cardiac output?
The volume of blood that is pumped by the heart per unit of time
84
How will cardiac output vary for someone who is fitter vs someone who does less exercise?
Individuals who are fitter often have higher cardiac outputs due to having thicker and stronger ventricular muscles in their heart
85
How can you calculate cardiac output?
Cardiac output = heart rate x stroke volume
Cardiac output = cm3 min-1
Heart rate = bpm
Stroke volume = cm3
86
What is heart rate and stroke volume?
Heart rate = number of times a heart beats per minute
Stroke volume = volume of blood pumped out of left ventricle during one cardiac cycle
87
What happens to the body during exercise?
- more aerobic respiration due to more frequent muscle contraction
- cells therefore require more O2 and produce more CO2 as a waste product
88
What are the 2 ways that the body responds to changes during exercise?
- increases rate and depth of breathing rate so more O2 enters and more CO2 is removed via gaseous exchange
- increases heart rate which transports more O2 and glucose to muscles, and removes CO2 due to higher rate of respiration
89
How is breathing rate controlled?
By respiratory centres in the medulla oblongata (inspiratory and expiratory centres) - transfers nerve messages from brain to spinal cord
90
What effect does the inspiratory centre have on breathing, how does it do this?
Controls inhalation
- sends nerve impulses along motor neurones to intercostal muscles in the ribs and diaphragm, causing them to CONTRACT
- volume of chest increases, pressure lowers
- difference in pressure causes air to flow into the lungs
- impulses sent to expiratory centre to inhibit its action
91
What effect does the expiratory centre have on breathing, how does it do this?
Controls exhalation
- stretch receptors in lungs are stimulated after inhalation, which causes nerve impulses to be sent to medulla oblongata and inhibit expiratory centre
- expiratory centre no longer inhibited, sends nerve intercostal muscles in ribs and diaphragm causing them to RELAX
- volume of chest decreases, pressure increases
- air flows out of lungs due to pressure difference
- stretch receptors become inactive (no longer inhibit inspiratory centre)
92
What effect does exercise have on blood pH and why?
Causes decrease in pH of blood
Extra CO2 in blood due to increase in rate of respiration, which dissolves to form carbonic acid. This quickly dissociates into H+ and HCO3-, H+ decreases pH of blood
93
How does exercise stimulate changes in breathing rate?
- chemoreceptors in medulla oblongata, aortic and carotid bodies detect the change
- nerve impulse sent to medulla oblongata which then sends more frequent nerve impulses to intercostal and diaphragm muscles to increase rate and strength of contractions
- this increases breathing rate (more O2 enters, more CO2 exhaled)
- restoring blood pH to normal levels
94
What is ventilation rate?
The volume of air that moves in and out of the lungs during a set time period
95
How is heart rate controlled?
By the cardiovascular control centre in the medulla oblongata which unconsciously controls the rate at which the SAN generates electrical impulses - and therefore the rate at which the atria contracts
96
What are baroreceptors and chemoreceptors found, what do they detect?
Baroreceptors = found in aortic and carotid bodies, stimulated by changes in blood pressure
Chemoreceptors = found in medulla oblongata, aortic and carotid bodies, stimulated by changes in levels of CO2 and O2 in the blood and blood pH
97
How do parasympathetic and sympathetic neurones affect the SAN?
Sympathetic neurones increase rate at which SAN generates electrical impulses (speeds up heart rate)
Parasympathetic neurones decrease rate at which the SAN generates impulses (slows down heart rate)
98
How does heart rate change with blood pressure?
High BP
- detected by baroreceptors who send impulses to CV control centre
- impulses sent along parasympathetic neurones, secrete acetylcholine
- acetylcholine binds to SAN receptors causing it to fire less frequently, slowing down heart rate
Low BP
- detected by baroreceptors who send impulses to CV control centre
- impulses sent along sympathetic neurones, secrete noradrenaline
- noradrenaline binds to SAN receptors causing it to fire more frequently, increasing heart rate
99
How does heart rate change with blood O2/CO2/pH
High blood O2/low CO2/high pH:
- detected by chemoreceptors, who send impulses to CV control centre
- sends impulses along parasympathetic neurones, secrete acetylcholine
- acetylcholine binds to SAN receptors causing it to fire less frequently, decreasing heart rate
Low blood O2/high CO2/low pH:
- detected by chemoreceptors, who send impulses to CV control centre
- sends impulses along parasympathetic neurones, secrete noradrenaline
- noradrenaline binds to SAN receptors causing it to fire more frequently, increasing heart rate
100
What are the 4 ways that breathing can be scientifically measured?
- tidal volume (volume of air breathed in or out during normal breathing)
- breathing rate (number of breaths in one minute)
- oxygen consumption (volume of O2 used up in a given time)
- respiratory minute ventilation (volume of air breathed in or out in a minute
101
How do you calculate respiratory minute ventilation?
Respiratory minute ventilation = tidal volume x breathing rate
102
What is a spirometer?
A piece of apparatus that can be used to measure breathing rate. As a subject breathes through the spirometer, a trace is drawn on a rotating drum of paper or a graph formed digitally
103
How can tidal volume be calculated from a spirometer?
Calculate the average difference in volume of gas between each peak and trough
104
How can breathing rate be calculated using a spirometer?
Count number of peaks on the trace in a minute
105
What is keyhole surgery?
Minimally invasive surgery carried out via a small incision, where a video camera and specialised medical instruments are inserted to perform the surgery
106
What are the benefits of keyhole surgery?
- less blood loss and scarring of the skin
- less opportunity for infection
- less pain post surgery, quicker recovery
107
What are the cruciate ligaments, how can they be repaired?
Cruciate ligaments found in the middle of the knees, connects thigh bone to lower leg bone
Damaged ligament can be removed and replaced by a graft from another tendon in patient's leg or from a donor's tendon
108
What are prostheses?
Artificial versions of missing or damaged body parts which may be used to replace entire limbs/parts of limbs
109
How are prostheses used to enable participation?
Can enable individuals to participate in sport again e.g. knee joint replacement enables people to be more mobile and participate in low impact sports
110
What are the impacts of too much or too little exercise?
Too much - immune suppression (specific immune system is depressed), damage to joints and bones causes inflammation as cartilage worn away
Too little - becoming overweight (obesity), heart problems and diabetes
111
What is doping?
The use of a substance or technique to illegally improve athletic performance
112
What are anabolic steroids and their side effects?
Substances which act as transcription factors to switch on genes linked to protein synthesis - increase muscle size and give user increased strength, speed and stamina
Side effects = organ damage, increased aggression, liver dysfunction and cancer
113
What are stimulants and their side effects?
Make the user more alert and able to react faster (greater endurance)
Side effects = aggressive behaviour
114
What are narcotic analgesics?
Very strong painkillers which enable users to maintain performances despite injuries
115
What is erythropoietin and its side effects?
A peptide hormone which switches genes on and off via secondary messenger system - produces enzymes for RBC production so more RBCs produced and therefore aerobic respiration is improved
Side effects = serious health problems and death, excess RBCs thicken blood leading to heart attacks/strokes
116
What are absolutists and rationalists?
Absolutists - think PEDs are morally wrong and should be banned from all sport
Rationalists - think that there are times when the use of PEDs can be justified
117
What are the arguments for the use of performance enhancing drugs?
- athletes should have freedom to choose
- may help overcome inequality in competitive sport
- competing at a higher level may only be possible for some athletes if they are using PEDs
118
What are the arguments against the use of performance enhancing drugs?
- many of these drugs are illegal
- give athletes an unfair advantage
- health risks are serious
- athletes may not be fully informed of health risks
