1 / 13

13 October 2008

13 October 2008. Chapter 9: Muscle physiology Lab this week: Sensory Physiology and Hearing All instructions provided during lab (no advance prep) Short preferable for testing cutaneous receptors of calf. Test # 2 Monday 20 October. Striated (with sarcomeres). Fig. 09.01.

ozzy
Download Presentation

13 October 2008

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 13 October 2008 Chapter 9: Muscle physiology Lab this week: Sensory Physiology and HearingAll instructions provided during lab (no advance prep)Short preferable for testing cutaneous receptors of calf. Test # 2 Monday 20 October

  2. Striated (with sarcomeres) Fig. 09.01 Cylindrical/polygonal branched fusiform Fusion of myoblasts produce multinucleated skeletal myofibers

  3. Fig. 09.02 Myofilaments

  4. dArk band and lIght band Fig. 09.03

  5. Fig. 09.05

  6. Fig. 09.09

  7. 1 AP in motor axon leads to 1 AP in myofiber because end plate potential (EPP) is always suprathreshold Fig. 09.15 Neuromuscular junctionmyoneural junction

  8. Action potentials are conducted into T-tubles Fig. 09.11a

  9. Fig. 09.11b

  10. Ca++ sequestration is slower than Ca++ release from SR Fig. 09.12 3 Roles of ATP Preview: one mechanism of fatigue is AP conduction failure in t-tubules at high fAP

  11. Sequence of Events Leading to Contraction of Skeletal Muscle • Action potential in motor axon • Release of Acetylcholine into synaptic cleft of NMJ • ACh binds to nAChRs in sarcolemma • Increase permeability to Na+ and K+ via nAChR (inotropic) • Sarcolemma depolarizes (End Plate Potential =EPP) • Threshold exceeded....AP generated and conducted across the sarcolemma • AP conducted into Transverse tubules • Depolarization detected by DHP (dihydropyridine) receptors in T-tubules • Conformational change in DHP receptors leads to opening of Ca++ channels in sarcoplasmic reticulum

  12. Diffusion of Ca++ out of SR into cytoplasm • Ca++ constantly pumped back into SR by primary active transport pumps in the SR membrane • Ca++ in SR stored in combination with Calsequestrin • Ca++ binds to troponin • Tropomyosin shifts to expose binding sites of F-actin • Myosin heads (which have already hydrolyzed ATP) bind to sites on F-actin • Powerstroke of myosin crossbridge • IF Ca++ AND ATP REMAIN AVAILABLE • CROSSBRIDGE RELEASES ADP AND FRESH ATP BINDS, PERMITTING RELEASE AND RE-FORMATION OF NEW CROSSBRIDGE • IF Ca++ unavailable (returned to sarcoplasmic reticulum) • tropomyosin covers F-actin binding sites • myosin head units unable to attach to actin......end of contraction.

  13. Examples: lifting a barbell Types of contractions a) Isometric b) Isotonic i) Concentric ii) Eccentric

More Related