Physiology Lab 7: Exercise and Diving Effects

Lab 7: Experiment 1 - Effects of Exercise

• Exercise increases heart rate and decreases pulse amplitude compared to resting state
• Heart rate increases due to norepinephrine release, which binds to S.A node (pacemaker) cells
• Pulse amplitude decreases because blood is directed to muscle groups needing the most oxygen during exercise
• Post-exercise, heart rate returns to normal as norepinephrine release stops
• Post-exercise, pulse amplitude increases; blood flow returns to tissues not supplied during exercise

Lab 7: Experiment 2 - Heart Rate and Diving

• Diving simulation decreases both pulse amplitude and heart rate
• Pulse amplitude decreases due to vasoconstriction
• Baroreceptors sense high pressure, triggering acetylcholine release that binds to heart's pacemaker cells, decreasing heart rate
• The body enters survival mode, increasing central blood flow to vital organs like the brain and heart
• Post-dive, heart rate and pulse amplitude return to 'resting' levels
• Oxygen is supplied to tissues that had restricted blood flow, redirecting oxygen towards vital organs

Lab 6: Experiment 1 - Lung Parameters and Exercise

• Exercise alters lung parameters
• Tidal volume increases after exercise
• Inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and vital capacity decrease after exercise
• Exercise increases CO2 production, increasing tidal volume by using IRV and ERV reserves
• Estimated residual volume calculation: TLC - VC

Lab 6: Experiment 2 - Lung Parameters by Sex

• Lung parameters differ between males and females
• Males typically have larger lung capacities than females due to biological size, increased lung size, and more tissue/cells that require oxygen

Lab 6: Experiment 3 - Predicted vs Measured Vital Capacity

• Predicted vital capacity is expected to be greater than measured vital capacity
• The formula used to predict vital capacity may not be comprehensive, considering only age, height, and sex

Lab 5: Experiment 1 - Worm Mass Change

• Explores how worm mass changes with varying seawater percentages
• As seawater concentration rises, worm mass decreases
• As seawater concentration falls, worm mass increases
• Worm tissues (250-400 milliosmolar) react to surrounding solute changes
• Hypertonic solutions (high solute) draw water out, decreasing mass, causing crenation
• Hypotonic solutions (low solute) cause water influx, increasing mass
• Mass change calculations:
  • Mass > 100 = weight gain
  • Mass < 100 = weight loss

Lab 5: Experiment 2 - RBC Diameter Change

• Investigates changes in red blood cell (RBC) diameter in different solutions
• Isotonic solutions maintain RBC's biconcave shape by preventing osmotic changes
• Hypertonic solutions shrink RBCs as water exits to higher solute concentrations
• Hypotonic solutions swell RBCs with water influx, making them spherical
• Summary:
  • Hypo- = increased diameter (swell)
  • Hyper- = decreased diameter (shrink)

Lab 8: Experiment 1 - Mass and Metabolic Rate

• Mass affects metabolic rate
• Metabolic rate is directly proportional to mass
• Larger animals require more energy/oxygen due to increased tissue mass, increasing cellular respiration, CO2 production and metabolic rate

Lab 8: Experiment 2 - Metabolic Rate and Temperature

• Temperature influences metabolic rate
• Metabolic rate increases with temperature increases, and decreases with temperature decreases
• Mealworms (ectotherms) depend on environmental temperature, affecting glycolysis and the TCA cycle as they are catalyzed by enzymes
• Enzymes lower activation energy, making reaction rates temperature-sensitive; higher temperature = faster metabolic rate, lower temperature = lower metabolic rate
• Extreme temperatures can denature enzymes, halting chemical processes
• Q10 Calculation: Q10 = metabolic rate at high temp / metabolic rate at 10 degrees lower
• Q10 of around 2 indicates a doubling of metabolic rate associated with enzyme activity

Lab 1: Experiment 1 - Pulse Amplitude and Temperature

• Temperature treatments alter pulse amplitude (peripheral blood flow)
• Heat increases average pulse amplitude compared to at rest
• Pulse amplitude decreases and returns to normal as the body cools down
• Thermoreceptors detect temperature changes in localized skin and signal the hypothalamus; homeostasis is triggered.
  • Vasodilation (relaxation) occurs in response to heat to dissipate excess heat
  • Vasoconstriction occurs in response to cold to prevent heat loss
• Summary:
  • Increased blood flow = increased pulse amplitude (heat dissipation)
  • Decreased blood flow = decreased pulse amplitude (heat retention)

Lab 1: Experiment 2 - Gravity and Blood Flow

• Gravity impacts peripheral blood flow
• Arm elevation decreases pulse amplitude compared to resting
• Arm lowering increases pulse amplitude compared to resting
• Arm elevation increases gravitational pull on blood, resulting in 'draining' due to less blood being supplied to the capillaries
• Arm lowering decreases gravitational pull, leading to 'pooling' from more blood being supplied to the capillaries

Lab 2: Experiment 1 - Reaction Times

• Comparing reaction times for auditory and visual cues
• Responses to auditory cues are typically faster than responses to visual cues
• The auditory pathway is shorter, enabling quicker responses
• Auditory system processes: sound waves → sensory hair cells (triggers AP)
• Visual system processes: photoreceptors → network of neurons → initial integration → processing of information → neurotransmitters involved; more complexity increases response time

Lab 2: Experiment 2 - Prism Goggles and Throwing

• Examining the effect of prism goggles on throwing accuracy
• Early throws with prism goggles cause greater horizontal displacement, as the body needs to adapt to visual changes
• With practice, throws become more accurate
• Removing the goggles causes throws to become displaced again as the body readjusts
• Visuomotor learning occurs as the thrown is adjusted

Lab 3: Experiment 1 - Metathoracic Leg Response

• Investigating if the metathoracic leg responds more to flexion or extension
• There is no right or wrong answer
• It depends on pin placement and axon responses

Lab 3: Experiment 2 - Chordotonal Organ Response

• How the chordotonal organ responds to leg movement amounts/angles
• Greater leg movement angles lead to more firing frequencies (action potentials)
• Chordotonal organs stretch and high afferent neuron activity informs the cockroach of leg position
• Chordotonal organs undergo sensory adaptation to filter unnecessary information; high firing frequencies are unsustainable
• A phasic-tonic responses occurs, as high initial firing frequency reduces but doesn't hit zero; it levels off

Lab 4: Experiment 1 - Grip Force and Electrical Activity

• Relationship between electrical activity (nerve stimulation) and grip force
• As grip force increases, EMG (electrical activity) increases
• A point is reached where further recruitment of motor units/force isn't possible, so EMG activity plateaus, resulting in tetanus, which means muscles cannot fully relax
• More motor units lead to more electrical activity which increases grip

Lab 4: Experiment 2 - Reflex Stimulation and EMG Activity

• Impact of reflex stimulation on EMG activity
• Body responds very quickly to stimuli
• Reflex responses are faster because the stimulus does not have to travel to the brain to react
• Mechanosensory receptors (muscle spindles) conduct the quick response
• Muscle spindles enter the spinal cord and synapse with motor neurons via a monosynaptic pathway
• Nerve synapses trigger motor neurons to contract the same muscle completing the reflex arc
• Muscle stretch excites muscle spindles leading to a reflex contraction of muscle (stretch reflex)