Frog Lab: Anatomy and Contraction Bioengineering/Physiology 3202 - PDF document

Frog Lab: Anatomy and Contraction Bioengineering/Physiology 3202 Frog Lab I Slide 1 Bioengineering 3202- Human Physiology Frog Heart Anatomy/Function • Shared ventricle but blood separated – Spiral fold – Initial flow through pulmonary because of reduced pressure – Resistance to flow varies with breathing (inhale reduces resistance) Frog Lab I Slide 2 Bioengineering 3202- Human Physiology 1

EC Coupling • Action potential causes influx of Ca 2+ • In mammals and birds, this causes release of more Ca 2+ • Ca 2+ interacts with actin/myosin to cause contraction • Pumps gather up Ca 2+ or remove it from cell Frog Lab I Slide 3 Bioengineering 3202- Human Physiology Regulation of Cellular Contraction Action Potential Twitch (tension) • Adjust pretension to improve spacing in contractile elements Ca i transient – Optimal spacing mV [Ca ++ ] • Works at tissue and whole gram t Ca i from I Ca heart levels Tension [% of maximum] 120 Total tension 100 80 60 Twitch tension 40 20 0 Passive (rest) tension 1 1.5 2 2.5 3 3.5 4 Striation Spacing [µm] Frog Lab I Slide 4 Bioengineering 3202- Human Physiology 2

Effect of Pretension isometric contraction active tension tension resting tension time Frog Lab I Slide 5 Bioengineering 3202- Human Physiology Frank Starling Mechanism • Increased filling produces increased output • Extension of cellular mechanism Total tension • Does not require neural input Twitch tension Passive (rest) tension Frog Lab I Slide 6 Bioengineering 3202- Human Physiology 3

Lab Goals/Tasks • Dissection of heart – Prepare according to web site – Bring digital camera to make photos • Measure contraction – Attach force transducer – Calibrate transducer – Measure contraction as function of pre-tension Frog Lab I Slide 7 Bioengineering 3202- Human Physiology In Situ Views Frog Lab I Slide 8 Bioengineering 3202- Human Physiology 4

Lab Preparation Frog Lab I Slide 9 Bioengineering 3202- Human Physiology 5