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Teaching the Poiseuille's Law to Brazilian physiology students with challenging exercises
Author(s) -
PrimolaGomes Thales Nicolau,
RomanCampos Danilo,
Duarte Hugo Leonardo Lucio,
Coimbra Candido Celso,
Cruz Jader Santos
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.575.13
Subject(s) - hagen–poiseuille equation , flow (mathematics) , chemistry , blood flow , viscosity , pressure gradient , tube (container) , physics , mechanics , thermodynamics , analytical chemistry (journal) , materials science , chromatography , medicine , composite material
The students used two different tubes to measure the flow of water and oil through a system connected to a reservoir (600 ml): A (2mm diameter, 110cm length) and B (4mm diameter, 110cm length). Exercise tasks: 1) Measured the water flow we found in A = 90 ml/min and B = 125 ml/min. Discuss vessel diameter and blood flow. 2) Measured the water flow through the two tubes we found A + B = 180 ml/min. Discuss series and parallel resistances. 3) We encouraged the students to change the height of water column in B (75 to 90 cm) and find the pressure gradient, ΔP= Pend − Pinitial= pgh, where p is the density of water (998 kg/m3), g is the gravitational acceleration constant (9.8 m/s2) and h is height of the fluid column (cm). Result: ΔP75 = 55 mmHg and ΔP90 = 66 mmHg. Flow in B with ΔP90:150 ml/min. Discuss the intravascular pressure gradient. 4) Changed the length of tube A (110 to 187 cm) we found a flow of 35 ml/min. Discuss vessel length and blood flow. 5) Changed water by oil in A the flow decrease to 3 ml/min. Attention for liquids viscosities (1 and 35 x10‐6 m 2 /s, respectively). Discuss the influence of blood viscosity in vessels flow. Finally, we introduced the Poiseuille Equation [Q= (N π r 4 /8nl)x Δ P] making analogies with the exercise values. This approach has been very attractive and challenging to Brazilian physiology students. Supported by CNPq.