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A Biology A Level > Topic 7 > Flashcards

Topic 7 Flashcards

(96 cards)

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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
How do muscles contract?
- Sliding filament theory
26
What is the sliding filament theory?
- 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.
27
How is the conc of calcium ions around a myofibril controlled?
- Released in response to nerve impulse - Channels open to allow ions to cross membrane - Taken back in via active transport
28
What is tropomyosin?
- Fibrous protein intertwined on the actin filaments
29
What is troponin?
- Globular protein found on tropomyosin
30
What is aerobic respiration?
- Breaking down a respiratory substrate in order to produce ATP using oxygen
31
What is the equation for aerobic respiration?
- Glucose + oxygen --> carbon dioxide + water + energy
32
What are the 4 stages of aerobic respiration?
- Glycolysis - Link reaction - Krebs cycle - Oxidative phosphorylation
33
Where does each stage of respiration take place?
- Glycolysis - cytoplasm - Link reaction - matrix - Krebs cycle - matrix - Oxidative phosphorylation - inner membrane of mitochondria
34
What happens in glycolysis?
- Glucose broken down to 2 molecules pyruvate - Producing 2 NADH and 2 ATP
35
What are the products of glycolysis?
- 2 pyruvate - 2 NADH - 2 ATP
36
What happens in the Link reaction?
- 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
37
What are the products of the Link reaction?
- 2 Acetyl coA - 2 CO2 - 2 NADH
38
What happens in the krebs cycle?
- 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.
39
What are the products of the Krebs cycle?
- 3 NADH - 2 CO2 - 1 ATP - 1 FADH 2x for each pyruvate
40
What happens in oxidative phosphorylation?
- 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
What is the role of carrier molecules in ETC?
- 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
How many ATP molecules are produced from each red NAD/FAD?
- 3 ATP for every NADH - 2 ATP for every FADH
43
How many molecules of ATP can be produced per molecule of glucose?
- 2 ATP in glycolysis - 2 ATP in Krebs cycle - 30 NADH and 4 FADH in oxidative phosphorylation = 38 ATP
44
What happens if there is no oxygen available in respiration?
- 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
Why is oxygen so important for aerobic respiration?
- It is the final electron acceptor - ETC cannot continue
46
What are the two different anaerobic pathways?
- Lactate pathway in animals - Ethanol pathway in yeast
47
What happens in the lactate pathway of anaerobic respiration?
- 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
What is lactate?
- Acidic (low pH) - Inhibits enzyme action - Transported to liver where it is converted to pyruvate
49
What does myogenic mean?
- Muscle which can initiate its own contractions without nervous stimulation
50
How does electrical activity in the heart stimulate the contraction of atria/ventricles?
- 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
What is an ECG?
- Electrocardiogram - Shows electrical waves produced by activity of heart
52
What is the P wave on an ECG?
- Caused by depolarisation of atria - Atrial systole
53
What is the QRS complex on an ECG?
- Peak cause by depolarisation of ventricles - Ventricular systole
54
What is the T wave on an ECG?
- Repolarisation of ventricles - Diastole
55
What are some heart problems which are diagnosed by ECGs?
- Tachycardia - heart beats too fast - Bradycardia - heart beats too slow - Fibrillation - irregular rhythm - Ectopic heartbeat - pause in heart beat
56
What is homeostasis?
- Maintaining a constant internal environment at dynamic equilibrium despite internal/external changes
57
Why is homeostasis of temperature important?
- Ensures maintenance of optimal conditions for enzyme action and cell function.
58
What happens when temp increases?
- Denature enzymes - Break bonds in tertiary structure - Change in active site so enzyme-substrate complex cannot form
59
Why is homeostasis of blood glucose important?
- Cells need a constant supply of energy in the form of ATP - Glucose is respired to supply ATP
60
Why is homeostasis of water in the body important?
- Cells to function optimally. - Takes up metabolic reactions
61
What is thermoregulation?
- Maintenance of internal body temperature
62
How are thermoregulatory responses generated?
- Thermoreceptors in hypothalamus/skin detect changes - Thermoregulatory centre in hypothalamus is stimulated - Sends impulses to effector
63
What are the body’s cooling mechanisms?
- 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
What are the body’s warming mechanisms?
- 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
How does the hypothalamus help to regulate body temperature?
- Detects via thermoreceptors - Monitors temperature of blood - Homeostatic response via motor neurons to effectors
66
What is negative feedback?
- Loop that reverses the effect of the original stimulus back to optimum
67
What is the process of negative feedback?
- Receptors detect change and signal to coordinator - Sends signals to effectors to make changes and return internal conditions - Linked by efficient communication systems
68
What is positive feedback?
- Loop where the stimulus responds to change by deviating away from optimum
69
How can hormones alter events inside a cell?
- Gene expression - Transcription factors to alter gene expression
70
How do steroid hormones cause changes inside a cell?
71
How do protein and peptide hormones cause changes inside a cell?
72
What is a neuronal system?
- Passes neurones via synapses through nervous system - Short term response
73
What is a hormonal system?
- Carry signals through blood where endocrine glands release hormones - Long term response
74
What are target cells?
- Have specific receptors for each hormone
75
What is cardiac output?
- The volume of blood pumped out the heart per unit of time
76
How does cardiac output vary?
- Fitter individuals have higher cardiac output - Thicker and stronger ventricles
77
What is heart rate and stroke volume?
- Heart rate = beats per minute - Stroke volume = volume of blood pumped out the heart during once cardiac cycle
78
What happens to the body during exercise?
- More aerobic respiration due to more frequent muscle contraction - Cells require more O2 and produce more CO2 as a waste product
79
What are two ways the body responds to changes during exercise?
- 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
How is breathing rate controlled?
- By medulla oblongata - Transfers nerve impulses from brain to spinal cord
81
What is inspiration?
- Sends nerve impulses along motor neurones to intercostal muscles and diaphragm - CONTRACT - Volume of chest increases, pressure lowers
82
What is expiration?
- Nerve impulses to intercostal muscles and diaphragm - RELAX - Volume of chest decreases, pressure increases
83
What effect does exercise have on blood pH?
- Decrease in pH of blood - Extra CO2 in blood due to increase in respiration
84
How does exercise stimulate changes in breathing rate?
- 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
How does heart rate change with high blood pressure?
- 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
How does heart rate change with low blood pressure?
- 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
What are the 4 ways that breathing can be scientifically measured?
- Tidal volume - Breathing rate - Oxygen consumption - Respiratory minute ventilation
88
What is keyhole surgery?
- Minimally invasive surgery - Small incision inserted into knee
89
What are the benefits of keyhole surgery?
- Less blood loss - Less chance of infection - Quicker recovery
90
What is the impact of overexercising?
- Immune suppression - Damage to joints - Bone and joint inflammation
91
What is the impact of underexercising?
- Obesity - Diabetes - High blood pressure
92
What are anabolic steroids and their side effects?
- 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
What are stimulants and their side effects?
- More alert and react faster - Side effects: aggression
94
What is erythropoietin and its side effects?
- Produces enzymes for red blood cell production so more produced for aerobic respiration - Side effects: Serious health problems, blood thickening
95
What are the arguments for the use of performance enhancing drugs?
- Freedom to choose - May overcome inequality - May be only possible to compete at high levels
96
What are the arguments against the use of performance enhancing drugs?
- Many are illegal - Unfair advantage - Serious health risks - Not fully informed

A Biology A Level (8 decks)

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