Class Notes (835,750)
Canada (509,374)
Biology (529)
BLG 251 (28)
Lecture

muscle 2

2 Pages
103 Views
Unlock Document

Department
Biology
Course
BLG 251
Professor
Shavin Malhotra
Semester
Summer

Description
Role of ATP and Phosphocreatine in Providing the Energy Supply During Muscle Contraction Stimulation Of Muscle Fibres By The Nervous System  CONTRACTION → myosin heads attach to actin binding sites / form temporary cross bridges / bridges rapidly break and reform / new cross bridges form further along actin filament / causing shortening of each sarcomere  WHEN STIMULATION STOPS → Ca2+actively taken up by sarcoplasmic reticulum / myosin head detaches from actin / cross bridges reform / muscle relaxes  NO ATP AVAILABLE → cross bridges cannot detach / muscle becomes stiff / unable to relax / extreme form: rigor mortis / occurs after death Cycle Of Events During Contraction Of A Myofibril  Ca2+ ions enter sarcoplasm during wave of depolarisation  Bind to troponin / changes shape of protein / removes block of tropomyosin / exposes actin binding sites  ATP binds to myosin / stimulates ATPase / RELEASES ENERGY  Allows myosin heads to form cross bridges with actin  Allows POWER STROKE: myosin head changes angle / pulls on actin filaments o Width of I band, H zone decrease → filaments overlap increases o Z lines move closer together → length of sarcomere decreases o No change to A band → lengths of filaments stay constant  Allows Ca2+ ions to be pumped back in by active transport  New ATP binds to myosin / allows detachment from actin  Myosin head changes to original position (cross bridges reform)  Next attachment to actin filament and power stroke can occur o Ca2+ and ATP required for cycle to continue Energy In Active Muscle Cells  Breakdown of phosphocreatine / releases PI + energy / attach to ADP / forms ATP
More Less

Related notes for BLG 251

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit