Thursday - Downing - muscle tissue

Question 1

What helps individual cells in muscle tissue function as a whole?

Answer 1

Connective tissue.

Question 2

Striated muscles. which is involuntary?

Answer 2

skeletal, cardiac. Cardiac is involuntary

Question 3

Where is actin in a myofibril?

Answer 3

In the I-band and the A-band

Question 4

Where is myosin in a myofibril

Answer 4

A-band, H-band, M-line

Question 5

Sarcoplasm

Answer 5

cytoplasm of a muscle cell. Between myofibrils.

Question 6

Sarcolemma

Answer 6

plasma membrane of a muscle cell, nucleii are directly underneath. Forms the T-tubules.

Question 7

sarcoplasmic reticulum

Answer 7

smooth ER of a muscle cell.

Releases calcium during contracture.

Question 8

General features of skeletal muscle

Answer 8

Striated, voluntary, well developed sarcoplasmic reticulum, multinucleated with nucleii at periphery.

Question 9

Be able to describe and explain the predictable filament pattern that you would observe in cross sections through the I-band, H-band, and the A-band

Answer 9

I-band - just actin filaments, small dots arranged hexagonally

H-band - Just thick (H, think heavy and thick) filaments (myosin). Larger dots

A-band - the teams all there. actin and myosin filaments together.

Question 10

What bands contract when a skeletal muscle cell contracts?

Answer 10

I-band, H-band.

Question 11

Where is the M band? What is interconnected there and what interconnects it?

Answer 11

At the center of the H-band, which is in the center of the A-band. It contains myomesin and interconnects the thick myosin filaments to maintain their specific lattice arrangement.

Question 12

What is a Z disk and what connects there?

Answer 12

Region where attachment of ends of actin

Question 13

Where does the transverse tubule (T-tubule) of the sarcoplasmic reticulum intersect myofibrils?

Answer 13

The A-I junction (z band in lower vertebrates)

Question 14

What releases calcium during muscle contracture?

Answer 14

Sarcoplasmic reticulum

Question 15

What is a “triad” made of?

Answer 15

T-tubule + two lateral cisternae of sarcoplasmic reticulum

Question 16

This is helically wound along grooves of the actin helix and prevents myosin binding.

Answer 16

Tropomyosin

Question 17

This binds calcium and releases tropomyosin from actin

Answer 17

Troponin complex

Question 18

Alpha-actinin

Answer 18

Component of the Z-disk. Holds actin filaments in register by binding them in parallel array.

Question 19

Titin

Answer 19

One of the largest molecules we know about. Helps position myosin filaments. extends from each half of a myosin filament to the Z-disk.

Question 20

Nebulin

Answer 20

Long, non elastic protein that helps anchor actin to z-disk. two molecules wrap around each filament.

Question 21

Disease characterized by weakness and easy fatigue of muscles, autoimmune response to the ACh receptor. What is it and what type of drug helps?

Answer 21

Myasthenia gravis.

ACh esterase inhibitors are both diagnostic and therapeutic. (AChE allows for the recycling of Ach)

Question 22

Alpha motor neuron

Answer 22

Causes a whole muscle to contract

Question 23

Golgi tendon organ

Answer 23

Spindle-shaped bodies comprised of collagen, sensory fibers that are between collagen fibers and are sensitive to stretching forces on tendons.

Question 24

General features of cardiac muscle

Answer 24

Striated, involuntary, t-tubule system, smaller SR than in skeletal muscle. Have intercalated disks (dark bands that frequently appear step-like). Single, centrally located nucleus.

Question 25

Which type of muscle has LOTs of mitochondia

Answer 25

cardiac muscle

Question 26

Where are the t-tubules located in cardiac muscle?

Answer 26

z-lines. They are wider than those in skeletal muscle.

Question 27

Purkinje fibers

Answer 27

modified cardiac muscle cells. They are the conduction system of the heart.

Question 28

General features of smooth muscle

Answer 28

No striations, no t-tubules, involuntary. They produce extracellular products like collagen, elastin, and growth factors.

Question 29

Doctor word for tapered ends (like seen in smooth muscle cells)

Answer 29

Fusiform.

Question 30

What type of cell’s nucleus “corkscrews” as the cell contracts?

Answer 30

smooth muscle.

Question 31

Neuromuscular spindle

Answer 31

Wrap around the bodies of muscles and detect whether or not the muscle is contracted (proprioception)

Question 32

Golgi tendon organ

Answer 32

Spindle shaped bodies comprised of collagen and enclosed by a thin capsule. Afferent (sensory) fibers penetrate between the collagen fibers. They are sensitive to stretching forces on tendons.

Question 33

Motor end plates

Answer 33

The ends of efferent fibers. they end mid-region on intrafusal fibers.