Muscle

Question 1

Organizational Hierarchy of Muscle

Answer 1

Muscle as Organs -> Fascicles -> Fibers -> Myofibrils ->Sarcomeres -> Myofilaments -> Proteins

Question 2

Botulinus toxin

Answer 2

blocks ACh release

Question 3

Curare

Answer 3

competes with ACh for its receptors

Question 4

Neostigmine

Answer 4

Acetylcholinesterase (AChE) inhibitor

Question 5

Hemicholinum

Answer 5

blocks choline reuptake

Question 6

Rigor Mortis

Answer 6

Most muscles stiffen 3-4 hours after death
Peak rigidity occurs at 12 hours as a result of:
- Inability of the dying cells to exclude calcium
-Calcium influx into muscle cells promotes binding of myosin cross-bridges
-No ATP available for cross bridge detachment
-Actin and myosin become irreversible cross-linked
Gradually dissipates over next 48-60 hours due to muscle protein breakdown

Question 7

Hypoxia

Answer 7

damages mitochondria, causes cytochrome C release, initiates apoptosis

Question 8

Reperfusion

Answer 8

yields O2 radicals that further damage membranes. Ca2+ influx and yields release from SR and mitochondria further stimulate apoptosis