Lab 7 Q&A

Skeletal Muscle Characteristics

The Motor Unit

Sarcomere anatomy

Skeletal Muscle Contraction

Skeletal Muscle Metabolism

Types of Muscle Fibers

Force of Contraction

Cardiac Physiology

Lab 8

Lab Purpose

To allow students to experiment with principles of cardiac physiology (specifically the sympathetic/parasympathetic regulation of heart) using a Langendorff experimental setup.

Lab objectives

• Describe the Langendorff heart experimental setup and the flow of Krebs solution through the
  heart.
• Understand the role of regulatory neurotransmitters on heart function.
• Understand the effects of different drugs on heart function.
• Design and perform your own experiment using the Langendorff setup.
• Describe the differences between skeletal and cardiac muscle.

Lab Safety

• This is a reasonably safe lab, just follow the instructions.

Using the Simulation

With these settings, the time is one second per block horizontally.

The strength is measured vertically, these settings give you 10 mV per box going vertically. Each mV is 2 mmHg. You always count the strength from baseline.

Design Your Own Experiment

Core Principles

Langendorff Experiment

Neurotransmitter/Drug effects

• Adrenaline (epinephrine)
  • Sympathetic
  • β1 receptor activation
  • Propanolol - β-blocker
  • Phentolamine - α-adrenergic antagonist
• Acetylcholine
  • Parasympathetic
  • M2 receptor
• Verapamil
  • Voltage-gated Ca2+ inhibitors.
  • Reduces strength of contraction.
  • These channels are also found in SA and AV nodes.

• Atropine
  • Antimuscarinic (AKA anticholinergic)
• Strophanthin
  • Inhibits Na ⁺/K ⁺ ATPase, inhibiting Na ⁺/Ca ²⁺ exchange, increasing intracellular Ca ²⁺.
  • Increases contractility and vagal response