Download - Muscle physiology
Table 12-3: Comparison of Three Muscle Types
Smooth Muscles: Contrasted to Skeletal Muscle
• Homeostatic role– Control fluid– Sphincters
• Tonic contractions– Support tubes– Move products
• Slow contractions– Little fatigue– Low O2 use
Smooth Muscles: Contrasted to Skeletal Muscle
Figure 12-25a: Types of smooth muscle
• Stimulation– Electrically coupled– Hormones– Paracrines– Various receptors– Single Unit – Multiple unit
• Single tapered cells
• Longer actin & myosin
Smooth Muscles: Characteristics
Smooth Muscle Contraction: Mechanism
Figure 12-28: Smooth muscle contraction
Smooth Muscle Relaxation: Mechanism
Figure 12-29: Relaxation in smooth muscle
Cardiac Muscle: Contrasted to Skeletal
• Short branched fibers
• Single nucleus
• Intercalated discs
• Gap junctions
• Stimulation– Pacemaker– Autonomic
• Hormonal
Cardiac Muscle: Contrasted to Skeletal
Figure 14-7h: ANATOMY SUMMARY: The Heart
Action Potentials
• Smooth muscle cells are linked electrically via gap junctions so they can stimulate each other causing a wave like action potential
• This is also referred to as a FUNCTIONAL SYNCYTIUM