1
Q
What is skeletal muscle?
A
- The type of muscle you move
2
Q
What is a flexor?
A
- A muscle that bends a limb when it contracts
3
Q
What is an extensor?
A
- A muscle that straightens a limb when it contracts
4
Q
What is an antagonistic pair?
A
- muscles that work together to a bone, an extensor and a flexor
5
Q
What is a tendon?
A
- MUSCLE TO BONE
6
Q
What is a ligament?
A
- BONE TO BONE
7
Q
What are muscle fibres?
A
- Large bundles of long cells that make up skeletal muscles
- The cell membrane is the sarcolemma
- Are multinucleate - contain many nuclei
8
Q
What is the sarcolemma?
A
- Some parts fold inwards and stick to sarcoplasm
- Folds are called transverse tubules
- They spread electrical impulses
9
Q
What is the sarcoplasmic reticulum?
A
- A network of internal membranes that run through the sarcoplasm
- Stores and releases calcium ions for muscle
contraction
- Stores and releases calcium ions for muscle
10
Q
What is the sarcoplasm?
A
- A muscle cells cytoplasm
11
Q
What are myofibrils?
A
- Long cylindrical organelles (in muscle fibres) made of proteins
- Specialised for contraction
- Made up of short units = sarcomeres
- Actin = I bands = thin myofilaments
- Myosin = A bands = thick myofilaments
12
Q
What is the process of the sliding filament theory?
A
- Impulses travel along a motor neurone =ing acetylcholine to be released into the synapse of the neuromuscular junction
- The muscle end plate depolarises (sarcolemma) =ing Ca ions to be released from the sarcoplasmic reticulum
- Ca ions bind to Troponin =ing change in shape and drags Tropomyosin
- Tropomyosin moves, exposing the myosin binding site on the Actin
- Myosin globular heads bind to the myosin binding site
- The Myosin head moves, dragging the Actin towards the M-line, shortening the sarcomere
- ATP is released and binds to the myosin head, causing the myosin head to detach from the binding site on the Actin
- ATPase is released and breaks down ATP into ADP + Pi, releasing energy
- The myosin head recocks to its original position
- Ca ions are actively transported back to the sarcoplasmic reticulum
- Troponin returns to its original shape, tropomyosin returns to its original position, blocking the myosin binding sites on Actin
- With another impulse the cycle repeats
13
Q
What is an action potential?
A
- Triggers an influx of calcium ions
- Depolarises the sarcolemma - Myosin heads can now bind to troponin
14
Q
What is the role of Calcium ions
A
- Its released from the sarcoplasmic reticulum and binds to troponin
- Troponin changes shape so tropomyosin moves
- Myosin binding site on actin is now exposed = actomyosin bridges can form
- Its presence also activates ATPase
15
Q
What is the role of ATP?
A
- Binds to myosin head and causes it to detach from the actin = muscle relaxed
- It breaks down into ADP and Pi = energy released
- The energy is used to recock the myosin head = ready for next contraction
16
Q
What are some defining factors of slow twitch muscles?
A
- contract slowly
- energy is released slowly
- don’t get tired as easily
- aerobic respiration
- higher capillary density
- can’t cope well w/ lactic acid build up
- higher fat stores
- lots of mitochondria and blood vessels
- for posture
- for endurance
- reddish in colour (b/c myoglobin)
17
Q
What are some defining factors of fast twitch muscle fibres?
A
- contract quickly
- energy is released quickly
- get tired quickly
- anaerobic respiration
- fewer capillaries
- can cope w/ ‘lactic acid’
- lower fat stores
- not a lot of mitochondria or blood vessels
- for fast movement
- for short bursts of speed and power
- whiteish in colour (b/c lack of myoglobin)
18
Q
What is aerobic respiration?
A
- A process where large amount of energy is released
- By splitting glucose into COշ and Hշ
- COշ is released as a waste product
- Hշ combines w/ Oշ to make HշO
19
Q
What is a metabolic pathway?
A
- A series of chemical reactions
C6H12O6 + 6O2 → 6CO2 + 6H2O - Energy released phosphorylates ADP to ATP (adds a phosphate)
- ATP then provides energy for biological processes
20
Q
What are the 4 stages of aerobic respiration?
A
- Glycolysis
- The link reaction
- Krebs cycle
- Oxidative phosphorylation
- Each reaction is controlled and catalysed by a
specific intracellular enzyme
21
Q
What are the Coenzymes?
A
- NAD and FAD transfers H b/w molecules
- Can reduce or oxidise a molecule (OIL RIG)
- Coenzyme A transfers acetate b/w molecules
22
Q
What is glucose?
A
- Can be used to respire, but other complex organic molecules can be used
23
Q
What is glycolosis?
A
- The splitting of one molecule of glucose into two molecules of pyruvate
- ANAEROBIC
24
Q
What are the stages of glycolysis?
A
- Phosphorylation
- Glucose is (surprisingly) phosphorylated
- 2 molecule phosphates (Pi) from ATP are added
- Creating 2 molecules of triose phosphate and 2
ADP - Oxidation
- Triose phosphate is oxidised (loses H)
- Forming 2 pyruvate
- NAD collects H ions = 2 reduced NAD (NADH)
- 4 ATP are produced but 2 were used in 1.
- The 2 NADH are used in oxidative
phosphorylation
- The two pyruvates go into the matrix of
mitochondria for link reaction
25
What is the Link Reaction?
- Converts pyruvate to acetyl coenzyme A (CoA)
- Enzymes and coenzymes are now needed
- NADH that's produced in mitochondrial matrix for oxidative phosphorylation
26
Link Reaction - STEPS
1. Pyruvate is decarbonated - C atom removed as CO2
2. NAD is reduced - collects H from pyruvate turning it into acetate
3. Acetate combines with CoA to from acetyl CoA
- ATP is not produced
- Occurs twice for every glucose molecule
= 4 pyruvate molecules
- For every glucose molecule, 2 molecules of acetyl of CoA go to stage 3 (Krebs Cycle)
27
What is the Krebs Cycle?
- Series of oxidation-reduction reactions, controlled by a specific intracellular enzyme
- Takes place in matrix of mitochondria
- Occurs once for every pyruvate molecule
28
Krebs Cycle - Steps
1. Acetyl CoA combines w/ oxaloacetate to citrate
- CoA goes back to link reaction to be used
again
2. Decarboxylation and dehydrogenation occurs
- 6C citrate molecule is converted to a 5C
molecule
- H is used to produce NADH
3. Decarbonation and dehydrogenation
occurs
- 5C molecule is converted to a 4C
molecule
- One FADH and two NADH are produced
- Substrate level phosphorylation occurs
- ATP is produced by transfer of
phosphate group from an
intermediate compound to ADP
- Citrate has been converted into
oxaloacetate, to be used in link reaction
again
29
What is oxidative phosphorylation?
- Otherwise known as ATP synthesis
- The energy carried by electrons from
reduced coenzymes is used to make ATP
- Reduced coenzymes = NADH and FADH
- 2 part process = ETC and Chemiosmosis
30
Oxidative Phosphorylation - Steps
1. H atoms released from NADH and FADH as
they're oxidised
- H atoms split into protons (H+) and
electrons (e-)
2. Electrons move down the ETC losing energy
3. Energy is used to actively transport protons
from matrix to inter-membrane space than
the matrix
4. Conc. of the H+ is higher in the inter-
membrane space than the matrix
- Creating an electrochemical gradient
5. H+ move down the electrochemical
gradient back to the matrix via ATP
synthase
Chemiosmosis = making of water
6. H+ movement generates ATP
7. At the end of ETC in the matrix, H+ and e-
and O2 (from blood) combine to make
water
- O2 is then seen as the final electron
acceptor
31
How do some metabolic poisons target electron carriers?
- Preventing the passing of electrons in
oxidative phosphorylation
- Stopping e- from moving down ETC -
stopping chemiosmosis
- NADH and FADH aren't oxidised so none for
Krebs cycle
- ATP synthesis in the cells end up seriously
reduced
- Not enough ATP to fuel ATP regulating
cellular processes
32
Respiration Practical
1. Fill up test tubes w/ equal amounts of KOH → to absorb CO2
2. In the experimental tube place 5 woodlice on a gauze above the CO2
3. Add a syringe in the control tube bung → to set fluid in manometer to a known level
4. Leave the apparatus for a set period of time
5. Measure how far the liquid in the manometer has moved → ↓in Oշ = ↓ pressure
6. Use the distance moved over time to calculate volume intake per minute
- Control variables = temp, KOH volume
33
Using a spirometer - equipment
Nose clip - all air breathed in and out is recorded
KOH - to absorb CO2
Water tank - allows movement of the lid
Kymograph - shows the spirometer trace
34
Using a spirometer
- When a person breathes in the trace will go down as there is less O2 in the tank
- the lid will go down
- When a person breathes out the trace will go up b/c some of the O2 is back in the tank
- the lid moves upwards
35
Using a spirometer - how to calibrate
1. Place a dot on the chart when O2 tank is empty
2. Fill tank w/ known value of medical grade O2
3. Place a dot where the tank is now
4. Calculate how many squares on the paper
5. Figure out a scale
36
What is the total lung capacity?
- the total volume the lungs can hold
37
What is the vital capacity?
- total volume of air you can breath in and out
38
What is the inspiratory capacity?
- the volume you can breath in
39
What is the inspiratory reserve volume?
- the extra volume from a big breath in
40
What is the functional residual capacity?
- total volume of the lungs when relaxed
41
What is the expiratory reserve volume?
- the extra volume from a big breath out
42
What is the residual volume?
- the volume in lungs to prevent the walls sticking together
43
What is the tidal volume?
- volume breathing in and out at rest
44
What is the ventilation rate?
- the volume of air breathed in or out in a period of time
45
What is the respiratory minute ventilation?
- volume of gas breathed in or out in a minute
- Tidal volume x breathing rate
46
Lactate
If not enough O2 is present, anaerobic respiration occurs
- No final acceptor so ETC's stop
- No decarboxylation so link and Krebs stop
- Net gain of 2 ATP of glycolysis keeps cells functioning.
47
What is the equation for glycolysis?
- Glucose → Pyruvate => Glycolysis
48
What is the equation for Phosphorylation?
2ADP + Pi → 2ATP => Phosphorylation
49
What is the equation for reduction?
2Pyruvate → 2Lactate => Reduction
50
What is the equation for oxidation?
2Lactate → 2Pyruvate => Oxidation
- In oxidation, H ๋ and e¯ are lost
- If H ๋ builds up it ↑acidity (lower pH)
- Some are accepted by NADH
- Enzymes are denatured
51
What is the fate of lactate?
- Used instead of glucose in cardiac cells
- Turned back into pyruvate in muscle cells when
enough O2 is present
- Transports to the liver in blood
- Converted to glycogen for storage
- Converted back to glucose and release back into
blood - inv glucogen
52
What is the Medulla Oblongata?
Part of the brain that contains two ventilation centres
- Inspiratory centre
- Expiratory centre
CONTROLS BREATHING RATE
53
How does the Medulla Oblongata worrk?
1. Sends nerve impulses to intercostal and diaphragm muscles
- They then contract
2. ↑volume in the lungs = ↓pressure in the
lungs
3. Sends nerve impulses to expiratory centre
to inhibit it
4. Air enters lungs b/c of pressure difference
b/w lungs and outside
5. Stretch receptors in the lungs are
stimulated as lungs inflate
6. They send nerve impulses back to the
medulla oblongata
- The inspiratory centre is now inhibited
7. The expiratory centre sends nerve impulses
to intercostal and diaphragm muscles
- They relax
8. The stretch receptors become inactive as
lungs deflate
9. Cycle repeats
54
The cardiovascular control centre
- In Medulla Oblongata
- Controls the rate at which SAN fires
- SAN generates electrical impulses to cause atria to contract
- Animals alter HR to respond to internal stimuli, eg. fainting from low BP
- Chemical and pressure receptors detect stimuli in the blood
- Pressure receptors = baroreceptors in aortic and carotid arteries
- Stimulated by BP
- Chemical receptors = chemoreceptors in
aortic and carotid arteries, and medulla
oblongata
- Monitor O2 and CO2 lvls in the blood
and pH
STEPS
1. Electrical impulses from receptors sent to medulla oblongata along sensory neurones
2. Cardiovascular control centre processes info
3. Sends impulse along para/ sympathetic neurones to SAN
4. Neurotransmitters released onto SAN = ↑ or ↓ HR
- Sympathetic nervous system = action, so
‘fight or flight’ = ↑ HR
- Parasympathetic nervous system = calm, so ‘
'rest and digest’ = ↓ HR
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A Level Biology (SNAB)
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