Biology 220 - Review - Exam 3 - 11-18-07

Biology 220 - Review - Exam 3 - 11-18-07 - EXAM 3 REVIEW...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
1.) The Cross-Bridge Cycle – how muscles move 2.) Action Potential – Neurons – Depolarization and Hyperpolarization 3.) Cell-Mediated vs. Humoral Response ESSAY #1: WHAT HAPPENS WHEN A MUSCLE CONTRACTS? PART 1 – NERVE IMPULSES AND CHEMICAL GRADIENTS Step 1: Myosin heads are relaxed but binding to actin is blocked by tropomyosin. Step 2: What happens is that we get a nerve impulse and the release of Acetylcholine, which depolarizes the muscle fiber – that signal (nerve impulse) is transmitted to the whole muscle fiber, including the transverse tubules. Step 3: When the muscle fiber depolarizes, it causes the release of Calcium ions from the sarcoplasmic reticulum. Step 4: Calcium enters the muscle fiber, it binds to treponin and it causes the tropomyosin to be moved away from the binding sites on the actin. o Binding sites are now available for myosin head to bind OPENS UP POSSIBILITY FOR FORMATION OF CROSS- BRIDGE CYCLE This is why Calcium is so important! It allows your muscles to contract and relax PART 2 – The Cross-Bridge Cycle MYOSIN HEADS ARE THE PUTTERS The Power stroke is process of the muscle contracting. Step 1: ATP undergoes hydrolysis, which energizes the myosin head, allowing it to move the muscle Step 2: Cross-Bridge forms between myosin head and actin binding sites Step 3: ADP and P (resulting from hydrolysis) are released and the thin filament is pulled towards the center (essentially muscle contracts at this point) Step 4: New ATP molecule binds to myosin head, allowing the cross-bridge to break. Step 5:
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/15/2008 for the course BIO 220 taught by Professor Cassiemajetic during the Fall '07 term at Allegheny.

Page1 / 4

Biology 220 - Review - Exam 3 - 11-18-07 - EXAM 3 REVIEW...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online