Exercise & Diving Effects on the Peripheral Nervous System

Lab 7: Experiment 1 - Exercise Effects on ECG and Peripheral Nervous System

• Exercise leads to an increased heart rate and decreased pulse amplitude compared to a resting state.
• Norepinephrine release causes an increase in heart rate as it binds to S.A node (pacemaker) cells.
• Reduction in pulse amplitude occurs because blood is directed towards muscle groups actively involved in exercise, which require more oxygen.
• Post-exercise, heart rate returns to normal as norepinephrine release stops
• Pulse amplitude increases as blood flow normalizes to tissues that were not supplied during exercise.

Lab 7: Experiment 2 - Diving Impact on Heart Rate and Peripheral Blood Flow

• Simulated diving causes a decrease in both pulse amplitude and heart rate.
• Vasoconstriction causes pulse amplitude to decrease.
• High pressure sensed by baroreceptors triggers acetylcholine release, which then decreases heart rate.
• The body enters survival mode, prioritizing blood flow to vital organs (brain and heart).
• Heart rate and pulse amplitude are restored to resting levels post-dive
• Oxygen is supplied to tissues that were initially restricted to facilitate oxygen delivery to vital organs.

Lab 6: Experiment 1 - Lung Parameter Changes After Exercise

• Exercise alters lung parameters by increasing tidal volume and decreasing inspiratory/expiratory reserve volume, as well as vital capacity.
• Increased CO2 production during exercise increases tidal volume, utilizing the IRV and ERV.
• Estimated residual volume is found by: TLC - VC = estimated residual volume

Lab 6: Experiment 2 - Lung Parameter Differences by Sex

• Males typically have larger lung capacities than females.
• Due to larger overall size, males have increased lung size, tissues, and cells.
• This requires more oxygen supply, reflecting in larger lung parameter numbers.

Lab 6: Experiment 3 - Predicted vs. Measured Vital Capacity

• Predicted vital capacity is expected to be greater than measured vital capacity.
• The calculation formula may not be reliable due to considering factors : Age, height, and sex only

Lab 5: Experiment 1 - Seawater Percentage Impact on Worm Mass

• Increasing seawater percentage causes a decrease in worm mass.
• Decreasing seawater percentage causes an increase in worm mass.
• Worm tissue osmolarity is 250-400 mOsm, so (25-40%) seawater is isotonic.
• Higher percentages (hypertonic solutions) cause water to move from the worm (low solute) to the solution (high solute), resulting in crenation and weight loss.
• Lower seawater percentages (hypotonic solutions) cause water to move into the worm (high solute) and expands the cells, resulting in weight gain.
• Mass > 100 = weight gain, Mass < 100 = weight loss

Lab 5: Experiment 2 - RBC Diameter Changes in Treatment Solutions

• RBCs maintain a biconcave shape due to equal osmotic pressure in isotonic solutions.
• Hypertonic solutions cause RBCs to shrink and decrease in diameter as water moves out.
• Hypotonic solutions cause RBCs to swell and increase in diameter due to water moving in.
• Hypo- = increased diameter (swell), Hyper- = decreased diameter (shrink)

Lab 8: Experiment 1 - Mass Relation to Metabolic Rate

• As mass increases, metabolic rate is expected to increase proportionally.
• Larger animals contain more tissue that requires more energy (oxygen).
• Cellular respiration happening in the body results in more carbon dioxide that needs to be expelled
• Metabolic rate increases to expel this.

Lab 8: Experiment 2 - Metabolic Rate Affected by Temperature

• An increase in temperature leads to an increased metabolic rate, and vice versa.
• Mealworms are ectotherms and depend on the environment's temperature to regulate glycolysis and the TCA cycle.
• Enzymes catalyze these processes but are affected by adjustment in temperature.
• Too hot or cold conditions can denature enzymes and inhibit these.
• A higher temperature = faster metabolic rate; Lower temperature = lower metabolic rate
• Q10 = metabolic rate at high temperature/metabolic rate at 10 degrees lower
• Q10 is around 2, and 2 represents an increase in metabolic rate (associated with enzyme activity).

Lab 1: Experiment 1 - Temperature Treatment Impact on Pulse Amplitude

• Heat treatment should increase average pulse amplitude as compared to resting levels.
• Pulse amplitude is expected to decrease during cool down and return to normal.
• The body detects changes by thermoreceptors, which signal the hypothalamus to initiate response adjustments.
• Vasodilation (relaxation) occurs in response to heat for excess heat release.
• Vasoconstriction occurs in response to cold to prevent heat loss.
• Increase in blood flow = increase in pulse amplitude (Get rid of heat)
• Decrease in blood flow = decrease in pulse amplitude (Keep heat in)

Lab 1: Experiment 2 - Gravity Effects on Peripheral Blood Flow

• Arm elevation leads to a decreased pulse amplitude versus resting.
• Arm lowering leads to an increased pulse amplitude compared to resting.
• Arm elevation increases gravitational pull on blood, draining it from capillaries.
• Arm lowering decreases gravitational pull, causing blood to pool in capillaries.
• Gravitational force affects our body and circulatory system.

Lab 2: Experiment 1 - Reaction Times for Auditory and Visual Cues

• Responses to auditory cues are faster than those to visual cues.
• Auditory pathways are shorter, thus responses are faster; sensory receptors activate the brain to respond quicker.
• Auditory system: sound waves → sensory hair cells (triggers AP)
• Visual system: photoreceptors → network of neurons → initial integration → processing of information → neurotransmitters; process is more complex and slower.

Lab 2: Experiment 2 - Horizontal Displacement in Throwing with Prismed Goggles

• Initial throws with prism goggles show great horizontal displacement since the body must adapt.
• Throws become more accurate with continued use of goggles.
• Removing the goggles causes displacement again until visuomotor learning adjusts for throwing style.
• These changes demonstrate the body's adaptation to changes through neural integration and visuomotor adaptation.

Lab 3: Experiment 1 - Metathoracic Leg Response

• Whether the metathoracic leg responds more to flexion or extension depends on the pins or the axons responding to either flexion or tension.
• Sensory neurons in the chordotonal respond to movement in order to make cockroaches aware of their movement/ surroundings.

Lab 3: Experiment 2 - Chordotonal Organ Response to Leg Movement

• The chordotonal organs are observed to respond to varying amounts/angles of leg movement.
• High bending angle results in more frequent firing of action potentials.
• Higher angle movement causes more stretch on the chordotonal organs, leading to increased frequency of action potentials.
• Over time the chordotonal organ filters out information to avoid no longer useful information
• There is an an initial high firing frequency and an exponential drop but doesn't stop the cell, instead continues at a steady rate.

Lab 4: Experiment 1 - Electrical Activity and Grip Force

• EMG activity increases with grip force until a maximum is reached.
• Tetanus happens when the muscles cannot fully relax during nerve stimulation.
• More motor units working results in increase in nerve signals (electrical activity).

Lab 4: Experiment 2 - EMG Activity and Reflex Stimulation

• The body responds quickly to stimuli.
• The signal doesn't need to processed by the brain since it needs to quickly get a response.
• Mechanosensory receptors, called muscle spindles facilitate the process.
• Monosynaptic pathway through the spinal cord allows immediate motor neuron response.
• This triggers nerve synapses with motor neurons, which travel back down into the same muscle group that the fibre is in, causing a contraction of that muscle group, completing the reflex arc.
• The muscle stretch causes excitation of muscle spindles and results in a reflex contraction of the muscle (stretch reflex).
• These reflexes are an important response as safety mechanisms of the body.