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Smooth & Cardiac Muscle: Membrane Potential & Motor Control Overview

Learn the distinctions between smooth & skeletal muscles, explore features of membrane potentials, and understand motor control systems in the body. Dive into topics like innervation, excitation-contraction coupling, and reflex arcs.

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Smooth & Cardiac Muscle: Membrane Potential & Motor Control Overview

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  1. 22 October 2008 • Midterm grades: Test 1 (35%), Test 2 (35%), quizzes (30%) • Look over Test # 2 (A3 should be D not B) • Comments on Test #2 • Today: • Smooth muscle & cardiac muscle (Ch 9) • control of body movement (Ch 10) • Monday: begin Ch 12 cardiovascular physiology • Lab next week: Frog Muscle II (see website)

  2. Chapter 9 B Properties of Smooth Muscle and Cardiac Muscle How does smooth muscle differ from skeletal muscle? (innervation, membrane potentials, excitation-contraction coupling, twitch duration, fatigue, etc. (Table 9-6 p.292) What are the features of membrane potential of smooth muscle? (pacemakers and slow waves) What are the differences between single-unit and multi-unit smooth muscle?(location, spread of excitation) What are the unique characteristics of cardiac muscle?(anatomical, electrical)

  3. Figure 9.34 from SR and influx during Action Potential or graded potential Special situation: Dephosphorylation & latch bridge

  4. Figure 9.35

  5. latchbridge

  6. Know the locations of single-unit and multi-unit smooth muscles Control of membrane potential by neurotransmitters, hormones, local factors for some smooth muscles (02, pH, stretch, vasodilators….)

  7. Diagram of Action Potential in Cardiac Myofiber • Duration ~ 300 ms, • Long refractory period • Prevents tetanic contractions of cardiac muscle

  8. Fig. 09.06 Know this table

  9. Chapter 10: Control of somatic motor systems Riding a bike, playing piano, swinging a bat or golf club….

  10. Decision to move Fig. 10.01 Initiates motor command Coordinates secondary movements Corticospinal and corticobulbar tracts Balance and complex learned movements Pathways? Examples of motor disorders: Huntington’s Disease and Cerebellar Disorder Reflex

  11. Local control SpindleAfferent • Muscle spindle • Stretch receptor • Intrafusal muscle fiber • What is their role? • The stretch reflex… • Follow the reflex arc • Be able to differentiate function of afferent fibers, alpha motor neurons, and gamma motor neurons

  12. Fig. 10.05ab

  13. Fig. 10.05c Co-activation of alpha and gamma motoneurons insures that the stretch of muscle can be detected regardless of the initial length or state of contraction of that muscle.

  14. Stretch Reflex Monosynpatic excitation of motoneurons of that muscle and synergistic muscles and polysynaptic inhibition of motoneurons to antagonistic muscles. Recall frog reflex lab and existence of spinal reflexes in single-pithed frogs. Also, example Christopher Reeve and patellar reflex.

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