Title: .Biology Semester 2
Tags: nerves transport immunity Muscles

Q: Why is maintaining 'resting potential' an active process?
A: Resting potential is maintained by using sodium potassium pumps
Pumping 3 Na+ out for every 2 K+ in
Against their concentration gradient by active transport
Requires ATP

Title: Action potential transmission by local circuit
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A: Voltage gated sodium ion channels allow influx of positive Na+ into action potential region
Q: Voltage gated sodium ion channels allow influx of positive Na+ into action potential region
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A: Na+ diffuses to more negative areas either side
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Na+ diffuses to more negative areas either side
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A: They become more positive
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They become more positive
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A: Region behind is hyperpolarised so does not reach threshold
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Region behind is hyperpolarised so does not reach threshold
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A: Region ahead is at resting potential, more likely to reach threshold
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Region ahead is at resting potential, more likely to reach threshold
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A: An action potential can be initiated in region ahead only.
Voltage gated sodium ion channels allow influx of positive Na+ into action potential region
Na+ diffuses to more negative areas either side
They become more positive
Region behind is hyperpolarised so does not reach threshold 
Region ahead is at resting potential, more likely to reach threshold
An action potential can be initiated in region ahead only.
Other fields (not shown on cards):
Settings: 1,1,0 | n,n,n,n

Q: Name two functions of the refractory period
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A: 1. Unidirectional impulse transmission; 2. Limit on number of action potentials that can be transmitted in a given time

Q: An action potential lasts approximately [...]
A: 3ms
Extra: (check if graph is presented)

Q: What is the maximum change in potential difference over the course of an action potential?
A: 110mV + difference of hyperpolarisation
(Not just 110mV!)

Q: State the two differences between strong stimuli and weak stimuli
A: Strong stimuli: greater frequency, greater number of neurones stimulated
Weak stimuli: lower frequency, lower number of neurones stimulated

Q: Explain why axon diameter affects speed of impulse transmission
A: There is less resistance for the movement of Na⁺
More surface area for diffusion

Q: What does TENS stand for and what is the purpose of this device?
A: Transcutaneous electrical nerve stimulation
Uses electrical impulses to reduce pain signals from affected area to CNS

Q: Action potentials all have the same [...]
A: amplitude

Q: The change in potential difference when Na⁺ ions first begin to diffuse into axon in response to a stimulus is called the [...]
A: generator potential

Q: What is the difference between voltage gated channels in a generator region versus those further along axon?
A: The voltage gated channels in generator regions are linked to transducers
These are able to convert one form of energy to another in response to environmental changes
(E.g. in retina of eye, transducers convert light energy to electrical energy, which triggers the linked voltage gated channels to initiate an action potential)
No transducers linked to voltage gated channels further along axon

Q: The two opposing pressures that regulate the fluid movement in and out of capillaries are:
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A: Hydrostatic pressure; Osmotic pressure (due to water potential)

Q: [...] ⇋ [...]
A: CO₂ + H₂O; H_2CO_3
Extra: Catalysed by carbonic anhydrase

Q: [...] of CO₂ produced by tissues combines with H₂O to form [...] acid
A: 85%; carbonic

Q: After H₂CO₃ dissociates in the RBC, [...] ions diffuse to the [...]
A: hydrogencarbonate; plasma

Q: HCO₃⁻ is carried in the blood plasma in [...]
A: solution

Q: About [...] of CO₂ remain as [...] dissolved in the [...]
A: 5%; carbon dioxide molecules; blood plasma

About 10% of CO₂ diffuses into RBC and combines with amine group (molecular formula -NH₂) of Hb

Q: [...] ⇋ [...]
A: CO₂ + Hb; carbaminohaemoglobin

Inside red blood cells, H₂CO₃ dissociates into HCO₃⁻ and H⁺ 
H⁺ destabilises oxyhaemoglobin
It releases its O₂ molecules
O₂ diffuses into tissues, Hb takes up some H⁺ to form haemoglobinic acid, HHb
HCO₃⁻ diffuses out of cell, chloride ions diffuse into cell to maintain electroneutrality
This is called the chloride shift

Inspiration increases volume of lungs, decreases the pressure, therefore a pressure gradient  is established with both  veins and lymph vessels

Q: What word means:
 The passage of white blood cells through the intact walls of the capillaries into the surrounding tissue
A: Diapedesis

Q: Breast milk containing antibodies is called [...]
A: colostrum

Ligament attaches bone to bone 
Tendon attaches muscle to bone

Q: Why do skeletal muscles need to be in antagonistic pairs?
A: Muscles cannot extend themselves, need an opposing force to extend
Allows movement to be controlled

Q: Name three adaptations of slow twitch muscle fibres for aerobic exercise
A: Lots of mitochondria for aerobic respiration
Lots of myoglobin to store more oxygen
Lots of capillaries to supply oxygen, remove carbon dioxide

Q: Describe the role of myoglobin in muscles
A: Myoglobin = local oxygen reservoire
Provides immediate oxygen
Binds to oxygen in high ppO2, dissociates in low ppO2

Q: Why may using dead/attenuated vaccines cause problems?
A: • Killing may not have been effective / attenuated pathogen could mutate to pathogenic form
• Causing full symptomatic disease
• May cause allergies
• May not initiate effective immune response

Q: How do memory cells act to give long term immunity?
A: • Carry immunological memory
• When exposed to same pathogen again, they recognise the pathogen's antigen
• Have a faster response
• Greater production of antibodies

Q: Why does the secondary immune response produce antibodies more rapidly than the primary? (2)
A: • Primary response is delayed due to clonal selection process - T helper cells activating B cells
• In secondary response B memory cells are present, activated directly, more rapid response

Q: Why is treating cancer cells with drugs that are attached to antibodies particularly effective?
A: • Cancer cells targeted, normal cells not damaged by drugs
• Lower dose required for drug to be effective

Q: State 3 factors which affect a pathogen's ability to cause disease
A: • Site of infection
• Invasiveness
• Toxicity

Q: What is the role of phosphocreatine in muscles?
A: Phosphocreatine can anaerobically donate a phosphate group to ADP to form ATP following an intense muscular or neuronal effort.
Conversely, excess ATP can be used during a period of low effort to convert creatine to phosphocreatine.
Phosphocreating ---> ADP
ATP ------> Creatine

Q: Why is it important that fast muscle fibres have a large glycogen store?
A: They respire anaerobically
Anaerobic respiration is inefficient so requires large amounts of glucose to produce enough ATP
Glycogen acts as a local reservoire to be broken down into glucose

Q: What is the function of capillaries supplying slow muscle fibres?
A: • Short diffusion pathway for oxygen and glucose for aerobic respiration
• Also for removal of waste products