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A Biology A Level > Topic 7 > Flashcards

Topic 7 Flashcards

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1
Q

What are ligaments?

A
  • Hold bone to bone
  • Strong connective tissue to control and restrict movement in the joint
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2
Q

What are tendons?

A
  • Hold muscle to bones
  • Strong connective tissue to enable the muscles to power joint movement
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3
Q

What are antagonistic muscles?

A
  • Muscles that work in pairs
  • Move in opposition directions
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4
Q

What is an extensor muscle?

A
  • A muscle that straightens a joint during contraction
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5
Q

What is a flexor muscle?

A
  • A muscle that bends a joint during contraction
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6
Q

What is a skeletal muscle?

A
  • Muscles in the body that are attached to a skeleton
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7
Q

How are muscle fibres specialised?

A
  • each fibres contain an arrangement of contractile proteins in the cytoplasm
  • each fibre is surrounded by cell surface membrane (sarcolemma)
  • each fibre contains many nuclei
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8
Q

What is the cytoplasm, cell surface membrane and endoplasmic reticulum called in a muscle fibre?

A
  • Sarcoplasm
  • Sarcolemma
  • Sarcoplasmic reticulum
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9
Q

What are T tubules?

A
  • Deep tube projections that fold from the sarcolemma
  • Spreads electrical impulses through muscle fibres
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10
Q

What are myofibrils?

A
  • Inside muscle fibres
  • Bundles of actin and myosin filaments
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11
Q

What is a sarcomere?

A
  • Short repeating units of myofibrils
  • Distance between adjacent Z lines
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12
Q

How are actin and myosin filaments organised in myofibrils?

A
  • I band, A band, H zone, M line, Z line
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13
Q

What is the I band made of?

A
  • only has thin actin filaments
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14
Q

What is the A band made of?

A
  • Both actin and myosin filaments
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15
Q

What is the H band made of?

A
  • In the A band
  • Only thick myosin filaments present
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16
Q

What is the M line made of?

A
  • Attachment for myosin filaments
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17
Q

What is the Z line made of?

A
  • Attachment for actin filaments
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18
Q

How is the structure of a muscle fibre related to its function?

A
  • Many mitochondria to supply ATP via aerobic respiration
  • Sarcolemma contain voltage gated channels to allow depolarisation of muscle fibres
  • Myofibrils allow contraction of muscles
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19
Q

What are the two types of muscle fibres?

A
  • Fast twitch
  • Slow twitch
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20
Q

What is a fast twitch muscle?

A
  • Muscles contract rapidly and produce powerful contractions
  • Anaerobic respiration for ATP
  • Fatigue quickly
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21
Q

What is a slow twitch muscle?

A
  • Muscles contact slower and work at endurance
  • Aerobic respiration for ATP
  • Fatigue slower
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22
Q

What are the adaptations of fast twitch muscles?

A
  • Large store of myoglobin
  • Rich blood supply to deliver oxygen + glucose quickly
  • high density of mitochondria to provide ATP
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23
Q

What are the adaptations of slow twitch muscles?

A
  • Thicker myosin filaments
  • High conc of glycogen
  • Phosphocreatine to replenish ATP
  • Less conc of myoglobin so pale colour
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24
Q

What is myoglobin?

A
  • Red molecule storing oxygen in muscles
  • Increases rate of oxygen absorption from capillaries
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25
Q

How do muscles contract?

A
  • Sliding filament theory
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26
Q

What is the sliding filament theory?

A
  • Acton potential arrives at neuromuscular junction, calcium ions are released from sarcoplasmic reticulum
  • Bind to troponin causing tropomyosin to move.
  • Exposes myosin binding sites on actin filament
  • Myosin attached forming cross bridges.
  • Myosin head bends, pulling actin filament over myosin
  • ATP binds to myosin head causing them to detach and move back to original position.
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27
Q

How is the conc of calcium ions around a myofibril controlled?

A
  • Released in response to nerve impulse
  • Channels open to allow ions to cross membrane
  • Taken back in via active transport
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28
Q

What is tropomyosin?

A
  • Fibrous protein intertwined on the actin filaments
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29
Q

What is troponin?

A
  • Globular protein found on tropomyosin
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30
Q

What is aerobic respiration?

A
  • Breaking down a respiratory substrate in order to produce ATP using oxygen
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31
Q

What is the equation for aerobic respiration?

A
  • Glucose + oxygen –> carbon dioxide + water + energy
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32
Q

What are the 4 stages of aerobic respiration?

A
  • Glycolysis
  • Link reaction
  • Krebs cycle
  • Oxidative phosphorylation
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33
Q

Where does each stage of respiration take place?

A
  • Glycolysis - cytoplasm
  • Link reaction - matrix
  • Krebs cycle - matrix
  • Oxidative phosphorylation - inner membrane of mitochondria
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34
Q

What happens in glycolysis?

A
  • Glucose broken down to 2 molecules pyruvate
  • Producing 2 NADH and 2 ATP
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35
Q

What are the products of glycolysis?

A
  • 2 pyruvate
  • 2 NADH
  • 2 ATP
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36
Q

What happens in the Link reaction?

A
  • Pyruvate oxidised (dehydrogenated) to produce acetate
  • Pyruvate decarboxylated to form CO2
  • reduced NAD formed from hydrogen released
  • Acetate combines with coA to form acetyl coenzyme A
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37
Q

What are the products of the Link reaction?

A
  • 2 Acetyl coA
  • 2 CO2
  • 2 NADH
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38
Q

What happens in the krebs cycle?

A
  • 2C acetyl coA combine with 4C oxaloacetate to form 6C citrate
  • Citrate decarboxylated (CO2 released) and dehydrogenated (NADH) to form 5C compound
  • 5C decarboxylated (CO2 released) and dehydrogenated (2 NADH and 1 FADH) 3 times
  • Dephosphorylated (ADP to ATP) to produce oxaloacetate.
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39
Q

What are the products of the Krebs cycle?

A
  • 3 NADH
  • 2 CO2
  • 1 ATP
  • 1 FADH

2x for each pyruvate

40
Q

What happens in oxidative phosphorylation?

A
  • H atoms from reduced NAD and reduced FAD from krebs cycle
  • Split into protons and electrons
  • electrons move down ETC and release energy which transports protons from matrix into intermembrane space
  • Chemiosmotic gradient of protons
  • Return to matrix via facilitated diffusion via ATP synthase
  • Causes synthesis of ATP
  • Oxygen is the final electron acceptor combining with protons and electrons to form water
41
Q

What is the role of carrier molecules in ETC?

A
  • Receive H atoms from reduced NAD and FAD
  • Split into e- and H+
  • Transferred via series of redox reactions
  • Energy released pumps H+ ions into intermembrane space
42
Q

How many ATP molecules are produced from each red NAD/FAD?

A
  • 3 ATP for every NADH
  • 2 ATP for every FADH
43
Q

How many molecules of ATP can be produced per molecule of glucose?

A
  • 2 ATP in glycolysis
  • 2 ATP in Krebs cycle
  • 30 NADH and 4 FADH in oxidative phosphorylation

= 38 ATP

44
Q

What happens if there is no oxygen available in respiration?

A
  • No final acceptor of electrons from ETC
  • ETC stops functioning
  • No more ATP produced
  • No oxidised NAD and FAD available from dehydrogenation
  • Krebs cycle stops
  • Link reaction stops
45
Q

Why is oxygen so important for aerobic respiration?

A
  • It is the final electron acceptor
  • ETC cannot continue
46
Q

What are the two different anaerobic pathways?

A
  • Lactate pathway in animals
  • Ethanol pathway in yeast
47
Q

What happens in the lactate pathway of anaerobic respiration?

A
  • Reduced NAD transfers hydrogen to pyruvate to form lactate
  • NAD can be reused in glycolysis
  • Pyruvate is a hydrogen acceptor
  • Lactate can be further metabolised and a small amount of ATP is produced
48
Q

What is lactate?

A
  • Acidic (low pH)
  • Inhibits enzyme action
  • Transported to liver where it is converted to pyruvate
49
Q

What does myogenic mean?

A
  • Muscle which can initiate its own contractions without nervous stimulation
50
Q

How does electrical activity in the heart stimulate the contraction of atria/ventricles?

A
  • Sinoatrial node becomes depolarised, initiating wave causing atria to contract
  • Non conducting septum tissue prevents wave of passing to ventricles
  • Depolarisation carried to AV node
  • Stimulation passed along the bundle of His, which divides into 2 conducting fibres called the Purkyne tissue
  • Purkyne fibres initiate wave of depolarisation causing ventricles to contract
51
Q

What is an ECG?

A
  • Electrocardiogram
  • Shows electrical waves produced by activity of heart
52
Q

What is the P wave on an ECG?

A
  • Caused by depolarisation of atria
  • Atrial systole
53
Q

What is the QRS complex on an ECG?

A
  • Peak cause by depolarisation of ventricles
  • Ventricular systole
54
Q

What is the T wave on an ECG?

A
  • Repolarisation of ventricles
  • Diastole
55
Q

What are some heart problems which are diagnosed by ECGs?

A
  • Tachycardia - heart beats too fast
  • Bradycardia - heart beats too slow
  • Fibrillation - irregular rhythm
  • Ectopic heartbeat - pause in heart beat
56
Q

What is homeostasis?

A
  • Maintaining a constant internal environment at dynamic equilibrium despite internal/external changes
57
Q

Why is homeostasis of temperature important?

A
  • Ensures maintenance of optimal conditions for enzyme action and cell function.
58
Q

What happens when temp increases?

A
  • Denature enzymes
  • Break bonds in tertiary structure
  • Change in active site so enzyme-substrate complex cannot form
59
Q

Why is homeostasis of blood glucose important?

A
  • Cells need a constant supply of energy in the form of ATP
  • Glucose is respired to supply ATP
60
Q

Why is homeostasis of water in the body important?

A
  • Cells to function optimally.
  • Takes up metabolic reactions
61
Q

What is thermoregulation?

A
  • Maintenance of internal body temperature
62
Q

How are thermoregulatory responses generated?

A
  • Thermoreceptors in hypothalamus/skin detect changes
  • Thermoregulatory centre in hypothalamus is stimulated
  • Sends impulses to effector
63
Q

What are the body’s cooling mechanisms?

A
  • Vasodilation of blood vessels so more blood flow to skin
  • Sweating cools skin via evaporation
  • Flattening of hairs stops hair from forming an insulation
64
Q

What are the body’s warming mechanisms?

A
  • Vasoconstriction of blood vessels so less blood flow
  • Shivering causes muscles to contract generating heat
  • Hairs stand up creating insulating layer
  • Less sweat to reduce heat loss via evaporation
65
Q

How does the hypothalamus help to regulate body temperature?

A
  • Detects via thermoreceptors
  • Monitors temperature of blood
  • Homeostatic response via motor neurons to effectors
66
Q

What is negative feedback?

A
  • Loop that reverses the effect of the original stimulus back to optimum
67
Q

What is the process of negative feedback?

A
  • Receptors detect change and signal to coordinator
  • Sends signals to effectors to make changes and return internal conditions
  • Linked by efficient communication systems
68
Q

What is positive feedback?

A
  • Loop where the stimulus responds to change by deviating away from optimum
69
Q

How can hormones alter events inside a cell?

A
  • Gene expression
  • Transcription factors to alter gene expression
70
Q

How do steroid hormones cause changes inside a cell?

A
71
Q

How do protein and peptide hormones cause changes inside a cell?

A
72
Q

What is a neuronal system?

A
  • Passes neurones via synapses through nervous system
  • Short term response
73
Q

What is a hormonal system?

A
  • Carry signals through blood where endocrine glands release hormones
  • Long term response
74
Q

What are target cells?

A
  • Have specific receptors for each hormone
75
Q

What is cardiac output?

A
  • The volume of blood pumped out the heart per unit of time
76
Q

How does cardiac output vary?

A
  • Fitter individuals have higher cardiac output
  • Thicker and stronger ventricles
77
Q

What is heart rate and stroke volume?

A
  • Heart rate = beats per minute
  • Stroke volume = volume of blood pumped out the heart during once cardiac cycle
78
Q

What happens to the body during exercise?

A
  • More aerobic respiration due to more frequent muscle contraction
  • Cells require more O2 and produce more CO2 as a waste product
79
Q

What are two ways the body responds to changes during exercise?

A
  • Increased rate of breathing so more O2 enters and more CO2 is removed via gaseous exchange
  • Increased heart rate which transports more O2 and removes CO2 due to high rate of respiration
80
Q

How is breathing rate controlled?

A
  • By medulla oblongata
  • Transfers nerve impulses from brain to spinal cord
81
Q

What is inspiration?

A
  • Sends nerve impulses along motor neurones to intercostal muscles and diaphragm
  • CONTRACT
  • Volume of chest increases, pressure lowers
82
Q

What is expiration?

A
  • Nerve impulses to intercostal muscles and diaphragm
  • RELAX
  • Volume of chest decreases, pressure increases
83
Q

What effect does exercise have on blood pH?

A
  • Decrease in pH of blood
  • Extra CO2 in blood due to increase in respiration
84
Q

How does exercise stimulate changes in breathing rate?

A
  • Chemoreceptors in medulla oblongata detect change
  • Nerve impulse sent to medulla oblongata which then sends more frequent nerve impulses to intercostal and diaphragm
  • Increases breathing rate
  • Restoring blood pH to return to normal
85
Q

How does heart rate change with high blood pressure?

A
  • High BP detected by baroreceptors who send impulses to CV control centre
  • Impulses sent along parasympathetic neurones, secrete acetylcholine
  • Bind to SAN receptors causing HR to slow
86
Q

How does heart rate change with low blood pressure?

A
  • Low BP detected by baroreceptors who send impulses to CV control centre
  • impulses sent along sympathetic neurones, secrete noradrenaline
  • Binds to SAN receptors causing it to increase
87
Q

What are the 4 ways that breathing can be scientifically measured?

A
  • Tidal volume
  • Breathing rate
  • Oxygen consumption
  • Respiratory minute ventilation
88
Q

What is keyhole surgery?

A
  • Minimally invasive surgery
  • Small incision inserted into knee
89
Q

What are the benefits of keyhole surgery?

A
  • Less blood loss
  • Less chance of infection
  • Quicker recovery
90
Q

What is the impact of overexercising?

A
  • Immune suppression
  • Damage to joints
  • Bone and joint inflammation
91
Q

What is the impact of underexercising?

A
  • Obesity
  • Diabetes
  • High blood pressure
92
Q

What are anabolic steroids and their side effects?

A
  • Acts as a transcription factor to switch on genes for protein synthesis
  • Increase muscle size and stamina
  • Side effects: organ damage, aggression, liver dysfunction, cancer
93
Q

What are stimulants and their side effects?

A
  • More alert and react faster
  • Side effects: aggression
94
Q

What is erythropoietin and its side effects?

A
  • Produces enzymes for red blood cell production so more produced for aerobic respiration
  • Side effects: Serious health problems, blood thickening
95
Q

What are the arguments for the use of performance enhancing drugs?

A
  • Freedom to choose
  • May overcome inequality
  • May be only possible to compete at high levels
96
Q

What are the arguments against the use of performance enhancing drugs?

A
  • Many are illegal
  • Unfair advantage
  • Serious health risks
  • Not fully informed

A Biology A Level (8 decks)

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