Topic 12

Question 1

Skeletal Muscle

Answer 1

Moves the skeleton of the body. Long, striated (striped) fibers with multiple nuclei
Ex: Your tongue, Diaphragm
-Breaks down ACh-ase
-Pumps the Ca2+ into the SR
-Myosin protein releases actin

Question 2

Smooth Muscle

Answer 2

wrap around internal tubes and control movement through the tubes (blood vessels or digestive tract) Not Striated. Cells are shorted and tapered at each end
Interconnected by gap junctions (proteins that link cell-to-cll electrically)
Ex: Organs, arteries
-Breaks down ACh-ase
-Pumps the Ca2+ into the SR and out of the cell
-Myosin protein releases actin

Question 3

Cardiac muscle

Answer 3

push on blood, to create blood flow. Found only in the walls of the heart. Striated (striped) and branched. May have one or more nuclei per cell. Cells are also interconnected by gap junctions
Ex: Muscle of the heart, not the arteries or veins
-Breaks down ACh-ase
-Pumps the Ca2+ into the SR and out of the cell
-Myosin protein releases actin

Question 4

Skeletal muscle Anatomy

Answer 4

1. Muscle
   2.Fibers(cells)
2. Bundles
3. Myofibrils (mini-fibers)
4. Sarcomeres

Question 5

Muscles

Answer 5

organ level of structure
-Made of many smaller groups of cells

Question 6

FIbers (cells)

Answer 6

made of many smaller bundles

Question 7

Bundles

Answer 7

Packed full of myofibrils

Question 8

Myofibrils (mini-fibers)

Answer 8

contain sarcomeres

Question 9

Sarcomeres

Answer 9

smallest unit of contraction in the muscle cell that can still generate force

Question 10

What are the three classes of proteins

Answer 10

Structural, Regulatory, and Contractile

Question 11

Structural proteins

Answer 11

Function: helps hold material in place (alignment)
Examples: Nebulin and Titan

Question 12

Regulatory Proteins

Answer 12

Function: oversees and controls when contractions can occur
Examples: Troponin and Tropomyosin (skeletal)
Calmodulin (smooth, sister protein to troponin)

Question 13

Contractile Proteins

Answer 13

Function: interact to create pulling force
Example: Actin and Myosin
Actin is the main proteins in microfilaments, helps with exocytosis and endocytosis

Question 14

Thin Filaments

Answer 14

made of bundles of proteins and ropes that get pulled
-consists of nebulin, tropomyosin, filamentous actin, tropin, and globular actin

Question 15

Thick Filaments

Answer 15

Hands that do the pulling
-consists of myosin, titin, ATP catalytic site, and actin binding domain

Question 16

ATP catalytic site

Answer 16

location where energy is invested to create movement

Question 17

Actin binding domain

Answer 17

two myosin are intertwined with one another

Question 18

Sliding filament theory of contraction

Answer 18

myosin globs grab onto and pull the actin proteins, but the actin proteins do not shorten, myosin does not shorten, only the overall sarcomere shortens

Question 19

Tension

Answer 19

pulling force (how muscles create force, they use tension)

Question 20

Twitch cycle

Answer 20

one cycle of contraction events at the sarcomere level (only occurs when calcium in cytoplasm is elevated)

Question 21

Muscle contraction steps

Answer 21

-the myosin head is recocked (setting the arm on a mouse trap)
-Cross-bridge formation
-Powerstroke
-ATP binds to myosin
-Myosin detaches from actin

Question 22

How does a muscle create tension?

Answer 22

It uses the myosin protein to pull on the actin protein

Question 23

What happens when a sarcomere contracts?

Answer 23

The thin filament (actin) is pulled toward the middle of the sarcomere

Question 24

What happens to the lenghts of the filaments during sarcomere contraction?

Answer 24

The length does not change, they are just pulled towards the middle of the sarcomere

Question 25

What happns to sarcomeres during contraction events?

Answer 25

They shorten

Question 26

What happens to the myosin heads during multipe twitch cycles?

Answer 26

Each myosin head moves from actin head to actin head along with each filament

Question 27

Neurotransmitter

Answer 27

type of ligand (chemical message) released by a neuron onto a target cell (close within a couple nanometers)

Question 28

Chemical Synapse

Answer 28

Common between neuron to skeletal muscle communication events

Question 29

Synapse general structure

Answer 29

join between a neuron (signaling cell) and its downstream target cell (could be a neuron,muscle cell, gland-type cell)

Question 30

Electrical synapse

Answer 30

common between interneuron to interneuron, smooth to smooth muscle, or cardiac to cardiac muscle. Skeletal muscle does not use this type

Question 31

Steps of Chemical Synapse - leading to contraction

Answer 31

1. Signaling neuron (motor neuron) sends AP to terminal, voltage-gated calcium channels activated allows calcium into presynaptic cell, triggers release of neurotransmitter into synaptic cleft, bind to receptors on post synpatic cell.
   2.Activation of those receptors (acetylcholine receptors) triggers a new AP along muscle fiber membrane
   3.As AP reaches into pockets (T-tubulus) triggers release of calcium inside the muscle cell from the Sarcoplasmic reticulum (SR)
2. Elevated calcium in the cytoplasm activates troponin, allows troponin to push tropomyosin out if the way, allows myosin to grab actin
   *AP means action potential

Question 32

Steps to Skeletal muscle relaxation

Answer 32

5. Acetylcholine (ACh) needs to be removed from the cleft, actycholinease, enzyme that breaks down ACh so that activitation is stopped
6. Need to remove calcium from the cytoplasm and lower the concentration – it is pumped into the SR (calcium ATPase/Pump) This protein transporter is using ATP and foring it upo the concentrate gradient
7. Myosin needs to let go of actin, ATP needs to bind to myosin
   Net effect– thin filaments turn into their resting position (recoiling) causes the sarcomere to streatch back to its relaxed state