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SNAB edexcel A-level biology > Run for your life > Flashcards

Run for your life Flashcards

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1
Q

What is an antagonistic pair

A

when one muscle contracts and the other one relaxes to induce a movement.

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1
Q

What are synovial joints?

A
  • synovial fluid is present between the bones
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2
Q

Wht to tendons do?

A

connect muscle to bone

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3
Q

what do ligaments do

A

connect bone to bone

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4
Q

what occurs in arthritis

A
  • swelling of joints - either bone ends rub together and cartilage in thinned (osteoarthritis)
  • or bone erosion due to a swollen, inflamed synovial membrane
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5
Q

What are extensors and flexors?

A

extensors extend the limb
flexors bend the limb

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6
Q

Describe the size by size comparison of a bundle to muscle fibers

A

bundle of muscle fibers –> one muscle fiber —> myofibrils —> sarcomere

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7
Q

What does a sarcomere contain

A

a repeated unit of actin and myosin filaments

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8
Q

Describe/define the following terms:

  • A Band
  • I band
  • H zone
  • Z disk
A
  • Region with overlapping of myosin and action filaments, including a myosin only area in the middle.
  • Actin only area
  • Only myosin filaments (in the middle of the A band)
  • Z disk links adjacent sarcomeres together, zigzag line with actin molecules on either side, leading to 2 different sarcomeres
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9
Q

describe what happens to the Bands when a muscle contracts

A
  • Z lines move closer together, I band gets smaller.
  • A band remains the same
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10
Q

Describe the role of calcium ions in muscle contraction.

A
  • bind to Tropomyosin is moved by troponin
  • this exposes the myosin binding sites on actin.
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11
Q

Describe the changes that help muscle contraction occur after Ca2+ ions are bound.

A
  • myosin heads can now bind to binding sides
  • this causes the myosin to change shape
  • actin filaments pulled over the myosin towards the M line
  • sarcomeres therefore shorten.
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12
Q

explain the interaction between Ca2+ ions, Troponin and Tropomyosin

A
  • Ca2+ binds to troponin, which causes it to change shape
  • This causes tropomyosin to move away from the myosin binding site.
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13
Q

Describe how the concentration of Ca2+ ions around the myofibrils is controlled

A
  • Ca2+ ions released from sarcoplasmic reticulum
  • in response to action potential at neuromuscular junction
  • Calcium channels open to allow ions to cross across the membrane
  • Ca2+ ions taken back into the sarcoplasmic reticulum by active transport.
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14
Q

Name the 4 stages in order of aerobic respiration

A
  • glycolysis
  • link reaction
  • Krebs cycle
  • oxidative phosphorylation
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15
Q

Describe the cardiac cycle

A
  • blood flows in through the vena cava, into the atria, increasing pressure.
  • this opens the AV valves, causing atrial systole to take place.
  • blood fills the ventricles, increasing pressure.
  • AV valves close, and SL valves open out of the ventricles into the heart.
  • diastole takes place.
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16
Q

what does myogenic mean in terms of the heart?

A

no external signal required to beat, beats on its own.

17
Q

describe how a heart beat is coordinated.

A
  • cells in the sinoatrial node become depolarised
  • depolarisation spreads through the walls of the atria, causing atrial systole.
  • Atrio ventricular node detect this depolarisation, sending impulses down the bundle of his (bundle of purkyne fibres) , and then down to the Purkyne fibres.
  • after a slight delay (to ensure ventricles contract after the atria), this causes ventricular systole.
  • ventricles contract from the apex upwards.
18
Q

Why can’t the ventricles receive the depolarisation from the SAN?

A

atria and ventricles separated by a layer of non conducting tissue. (annulus fibrosus)

19
Q

name 4 factors that effect heart rate

A
  • low pH
  • Stretch receptors
  • decrease in BP
  • Adrenaline
20
Q

Describe the process of glycolysis

A
  • glucose is phosphorylated to produce 2 pyruvate molecules, 2 ATPs and 2 NADH (end products)
  • Glucose is phosphorylated to glucose bisphosphate.
  • splits into triose phosphate, and this is oxidised to pyruvate. (NAD is reduced to NADH)
21
Q

Describe the processes involved in the Link reaction.

A
  • Pyruvate is oxidised (NAD–> NADH)
  • simultaneously, it looses a Carbon (due to the coenzymeA)
  • this produces CO2 and AcetylCoA and NADH as final products
22
Q

Describe the processes involved in the krebs cycle

A
  • acetylCoA reacts with a 4C compund to produce a 6C compound. In this process, CoA is reformed and goes back to the link reaction.
  • the 6C compund is oxidised to a 5C compound - where NAD is reduced to NADH, and CO2 is produced
  • this 5C compund is then resynthesised to the original 4C compound - producing 2NADH, 1FAD, and 1ATP molecule. (CO2 also produced)
23
Q

Describe the processes involved in oxidative phosphorylation

A
  • the Hydrogen carriers (NADH and FAD) are oxidised, producing electrons and H+ ions
  • the electrons go through electron transport proteins, a series of redox reactions.
  • the energy released from these reactions is used to actively pump H+ ions into the intermembrane space.
  • H+ ions then diffuse back down an electrochemical gradient, through ATP synthase, which simultaneously produces ATP from ADP + Pi
  • the H+ ions are accepted by oxygen, forming water.
24
Q

How is lactate formed?

A
  • when pyruvate accepts a H from NADH
25
Q

What is substrate level phosphorylation?

A
  • enzymes remove a “high-energy” phosphate from an organic substrate and directly transfer it to ADP to form ATP​
26
Q

describe the process of anaerobic respiration during glycolysis

A

glucose is converted into
pyruvate by glycolysis

the pyruvate is then further converted into lactate with the help of NADH in a process known as lactate fermentation.

Lactate is then converted back to pyruvate in the liver.

27
Q

Describe the whole process of the sliding filament theory in muscle contraction.

A
  • Ca2+ ions released from sarcoplasmic reticulum
  • Ca2+ ions bind to troponin
  • troponin binds to tropomyosin, and moves it aside to expose myosin binding sites
  • Myosin heads have ADP attached - which enable them to the binding site on acting and create a cross bridge.
  • Myosin heads release their ADP molecules when they slide actin (creating an angle that creates tension)
  • ATP molecules bind to myosin heads to dettach the myosin heads.
  • the ATPase in the myosin heads hydrolyse ATP.
  • this returns myosin heads to their starting positions - ready for another cycle.
28
Q

What happens to lactate after a period of anaerobic respiration?

A
  • transported back to the liver where it is converted to glucose.
29
Q

what is the enzyme that catalyses the formation of lactate from pyruvate?

A
  • lactate dehydrogenase.
30
Q

Describe the benefits of moderate exercise.

A
  • increases NK cell count and activity
  • prevents obesity as energy output is happening, preventing risks for hypertension, diabetes etc.
  • increased bone density, reducing risk of osteoporosis
  • increases vasodilation, lowering BP, decreasing chances of hypertension.
31
Q

Describe the drawbacks of intense excersise.

A
  • increases the chances of upper respiratory tract infections
  • increases risk of joint injuries - torn ligaments, inflammation, damaged cartilage etc.
32
Q

Name some advantages of keyhole surgery

A
  • less invasive so easier recovery
  • less blood loss
  • less pain
33
Q

Define the term doping

A
  • the use of banned performance enhancing drug in sports
34
Q

Describe the role of the brain in reducing heart rate after exercise

A
  • chemoreceptors detect decrease in blood pH
  • thus resulting in impulses being sent to the SAN to decrease heart rate.
35
Q

Describe how the brain reduces sweat production after the body cools down to its base temp

A
  • thermoreceptors detect decrease in temperature
  • thus, less impulses are sent to the sweat glands from the thermoregulatory centre in the hypothalamus.
36
Q

Describe how thermoregulatory mechanisms are controlled to help marathon runners avoid
heat stress.

A
  • thermoreceptors in the hypothalamus detect change in temperature environment
  • thermoregulatory centre in hypothalamus is stimulated.
  • The hypothalamus sends impulses to sweat glands to produce more sweat
  • vasodilation occurs, increasing blood flow to surface of skin.
37
Q

Give 2 arguments against doping

A
  • health concerns
  • gives athletes who use it an unfair advantage
38
Q

Explain the role of the nervous system in bringing about the increase in
temperature of the fingertip

A
  • thermoreceptors detect increase in temperature
  • thermoregulatory centre in hypothalamus is activated
  • impulses sent through sympathetic nervous system
  • causes constriction of shunt vessels
  • this causes vasodilation
  • allowing more blood to flow to the surface of the skin.
39
Q

Describe how transcription factors work to bring about a change in gene expression

A
  • transcription factors bind to the promoter region, forming a transcription initiation complex with RNA polymerase.
  • this results in the synthesis of mRNA.
40
Q

Where does the repressor bond to on the operon?

A

the operator region

SNAB edexcel A-level biology (8 decks)

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