1. Biopotentials

Question 1

Uses of Biopotentials

Answer 1

• receptor cells
• information transfer (neurons)
• muscle contraction
• hormone discretion
• bioelectrical organs for self defence

Question 2

phospholipid bilayer

Answer 2

• double layer of hydrophilic and hydrophobic

- large molecules can’t pass, small polar molecules repelled, small non-polar molecules (O2 CO2) can

Question 3

electrochem equilibrium

Answer 3

balance of diffusion and electric forces

Question 4

experiment - 3 phases

Answer 4

1. pot of Na and Cl, diffusion takes place, no change in voltage/potential across membrane
2. added voltage source, creates [ ]
3. remove voltage source, [ ] stays
   equivalent circuit

Question 5

relative permeability

Answer 5

gK / gCl = 10/3 - more likely to let K+ ions pass through

Question 6

action potential, cause

Answer 6

rapid reversal in charge across portion of membrane resulting in the sequential opening/closing of Na and K channels
5 phases: resting, threshold, rising, falling, recovery

Question 7

sources of action potential

Answer 7

1. sensory cells - vestibular system (inner ear, system involved in balance and movement) - cilia hair like structure when bent cause hyperpolarization, vv
2. neurotransmitters:
   
   • excitatory -> depolarization -> more likely ap
   • inhibitory -> hyperpolarization -> less likely ap

Question 8

post synaptive potential

Answer 8

• temporary change in electric membrane polarization
• hyperpolarization (increase neg charge inside) - inhibitory PSP b/c inhibits neuron from firing inpulse
• depolarization (decrease neg charge inside) - excitatory PSP b/c generates impulse if threshold
• graded potential - degree depends on activation of channels
• summation - can combine multiple (spatial, temporal)

Question 9

conduction of ap

Answer 9

1. myelinated

2. unmyelinated

Question 10

volume conduction

Answer 10

transmission of electric / magnetic fields from electric primary current source through biological tissue towards measurement sensors

Question 11

ECG

Answer 11

records heart activity using electrodes
forward problem: determine field (heart) from source (surface)
inverse problem: determine source from field

Question 12

MEG

Answer 12

neuro-imaging technique for mapping brain activity by recording magnetic fields produced by currents in the brain

Question 13

EMG

Answer 13

measures electrical activity of muscle tissue

Question 14

EEG

Answer 14

records electrical activity of heart by electrodes on scalp
set up: electrodes on scalp w gel, each electrode has wire attached to diff amp (60-100 db gain), a-to-d digitization, band pass filter, notch filter (power line)
frequency bands: delta, theta, alpha, beta, gama

Question 15

eeg frequency band examples

Answer 15

delta - babies, sleep (adult)
theta - young children, drowsiness (older)
alpha - closing eyes, relaxed
beta - alert, anxious, active busy
gamma - certain cognitive or motor functions