Muscular System

Question 1

Skeletal Muscle

Answer 1

Causes voluntary body movements

Attached to bones

Striated

Multinucleated

T-tubule system

Question 2

Smooth Muscle

Answer 2

Lines wall of blood vessels

Lines digestive tract

Mono nucleated
Tapered shape

Not striated

No T-tubule system (contraction is slow and highly regulated)

Question 3

Cardiac Muscle

Answer 3

Involved in rhythmic contractions of the heart

Involuntary

Striated, branched. cross linked to each other

mono or bi nucleated

Cells connected by gap junctions

Generates its own AP, which spreads rapidly throughout muscle tissues by electrical synapses across gap junctions

Question 4

Muscle Fiber

Answer 4

Cell in a muscle

Multinucleated

Nuclei lie along periphery of cell

Question 5

Sarcolemma

Answer 5

PM of muscle cell

Invaginated by T-tubules

Question 6

Sarcoplasm

Answer 6

Cytoplasm of muscle cell

Contains sarcoplasmic reticulum (ER of muscle cell) which stores Ca

Question 7

Myofibrils

Answer 7

Fill nearly entire volume of muscle cells

Contains microfilaments

Question 8

Actin

Answer 8

Thin filaments

2 strands of globular actin protein arranged in a double helix

Troponin and tropomysoin (sit on actin proteins, covering binding sites)

Question 9

Myosin

Answer 9

Thick filaments

Filamentous protein with protruding head on one end

Filaments laid together so that there are numerous protruding heads on both ends

Question 10

Sarcomere

Answer 10

In a myofibril, actin and myosin run paralle to each other

Filament overlap, creating striated appearance in skeletal muscle

Each repeating unit is a sarcomere

Question 11

Z line

Answer 11

Separates sarcomeres

Where actin is attached (no myosin at z line

Question 12

Sliding Filament Model- Attachement

Answer 12

Myosin head attached to actin filament when nothing is bound to head

Question 13

Sliding Filament Model-Release

Answer 13

ATP binds to myosin, causing it to release from actin

Question 14

Sliding Filament Model-Cocked

Answer 14

ATP hydrolyze to ADP

Pushes myosin head into “cocked” position

ADP still attached to myosin head

Question 15

Sliding Filament Model- Binding Sites Exposure

Answer 15

Ca binds to troponin, causing tropomyosin to expose positions on actin filament for myosin heads to attach to

Question 16

Sliding Filament Model- Cross Bridges

Answer 16

Formed between myosin and actin filaments

Question 17

Sliding Filament Model- ADP Release

Answer 17

ADP and PI are released

Sliding motion of actin results

Myosin released like a spring, generating a sliding movement of actin towards center of sarcomere

2 Z lines pulled together, contracting muscle fiber

ATP binds to myosin, releasing it from actin, cycle starts over

Question 18

Rigor Mortis

Answer 18

IF no more ATP generated in body (after death), there is nothing to bind myosin and cause it to release from actin

Causes stiffness of corpses

Eventual degradation of the ATP causes rigor mortis

Question 19

NMJ

Answer 19

Neurons synapse with muscle cells

AP generates ACH release

AP generated on sarcolemma and throughout T-tubules (receptors on sarcolemma bind ACH and open Na channels)

Sarcoplasmic reticulum releases Ca in response to AP

Ca binds to troponin

Cross bridges form

Power stroke occurs if ATP is available

Question 20

Myogenesis of Skeletal muscles

Answer 20

myoblasts fuse together to form large multinucleated cell

Unique to skeletal muscles

Question 21

Myoblast

Answer 21

Progenitor cells (can differentiate, but more specialized than stem cells