Sumários
Factors Affecting Heart Rate in Daphnia
26 Novembro 2025, 10:30 • Marta Cristina Silva Pimentel da Silva
This practical class investigated how ethanol affects heart rate, using Daphnia (water fleas) as a model organism.Daphnia are small freshwater crustaceans that have a myogenic heart—like vertebrates—where contractions originate in the cardiac muscle itself rather than being triggered by nerve impulses.
Students measured Daphnia heart rate under three conditions: 1) Control – culture water only (60 minutes), 2) 5% ethanol – baseline in water, then ethanol exposure, then recovery in water, and 3) 10% ethanol – same sequence at higher concentration. Heart beats were counted over 15-second intervals at set time points, converted to beats per minute, and expressed as a percentage of the initial rate. Ethanol acted as a non-selective nervous system depressant, decreasing heart rate. The mechanism involves modulation of acetylcholine levels. The recovery phase (returning to culture water) let students observed whether the effect was reversible. At the end students represented the data using an xy graph with % of initial heart rate/min on the Y-axis vs. time (in min) on the X-axis.
A quizz was performed for continuous evaluation.
Factors Affecting Heart Rate in Daphnia
26 Novembro 2025, 09:30 • Marta Cristina Silva Pimentel da Silva
This practical class investigated how ethanol affects heart rate, using Daphnia (water fleas) as a model organism.Daphnia are small freshwater crustaceans that have a myogenic heart—like vertebrates—where contractions originate in the cardiac muscle itself rather than being triggered by nerve impulses.
Students measured Daphnia heart rate under three conditions: 1) Control – culture water only (60 minutes), 2) 5% ethanol – baseline in water, then ethanol exposure, then recovery in water, and 3) 10% ethanol – same sequence at higher concentration. Heart beats were counted over 15-second intervals at set time points, converted to beats per minute, and expressed as a percentage of the initial rate. Ethanol acted as a non-selective nervous system depressant, decreasing heart rate. The mechanism involves modulation of acetylcholine levels. The recovery phase (returning to culture water) let students observed whether the effect was reversible. At the end students represented the data using an xy graph with % of initial heart rate/min on the Y-axis vs. time (in min) on the X-axis.
A quizz was performed for continuous evaluation.
Factors Affecting Heart Rate in Daphnia
25 Novembro 2025, 17:00 • Marta Cristina Silva Pimentel da Silva
This practical class investigated how ethanol affects heart rate, using Daphnia (water fleas) as a model organism. Daphnia are small freshwater crustaceans that have a myogenic heart—like vertebrates—where contractions originate in the cardiac muscle itself rather than being triggered by nerve impulses.
Students measured Daphnia heart rate under three conditions: 1) Control – culture water only (60 minutes), 2) 5% ethanol – baseline in water, then ethanol exposure, then recovery in water, and 3) 10% ethanol – same sequence at higher concentration. Heart beats were counted over 15-second intervals at set time points, converted to beats per minute, and expressed as a percentage of the initial rate. Ethanol acted as a non-selective nervous system depressant, decreasing heart rate. The mechanism involves modulation of acetylcholine levels. The recovery phase (returning to culture water) let students observed whether the effect was reversible. At the end students represented the data using an xy graph with % of initial heart rate/min on the Y-axis vs. time (in min) on the X-axis.
A quizz was performed for continuous evaluation.
Factors Affecting Heart Rate in Daphnia
25 Novembro 2025, 16:00 • Marta Cristina Silva Pimentel da Silva
This practical class investigated how ethanol affects heart rate, using Daphnia (water fleas) as a model organism. Daphnia are small freshwater crustaceans that have a myogenic heart—like vertebrates—where contractions originate in the cardiac muscle itself rather than being triggered by nerve impulses.
Students measured Daphnia heart rate under three conditions: 1) Control – culture water only (60 minutes), 2) 5% ethanol – baseline in water, then ethanol exposure, then recovery in water, and 3) 10% ethanol – same sequence at higher concentration. Heart beats were counted over 15-second intervals at set time points, converted to beats per minute, and expressed as a percentage of the initial rate. Ethanol acted as a non-selective nervous system depressant, decreasing heart rate. The mechanism involves modulation of acetylcholine levels. The recovery phase (returning to culture water) let students observed whether the effect was reversible. At the end students represented the data using an xy graph with % of initial heart rate/min on the Y-axis vs. time (in min) on the X-axis.
A quizz was performed for continuous evaluation.
Osmorregulação
24 Novembro 2025, 14:00 • Rita Carlos