Anatomy - Muscles

Front 1

What specialized cells are capable of contraction?

Back 1

Myoepithelial cells (glands)
Pericytes (precapillary)
Myofibroblasts (wound contraction)
Muscle cells (muscles)

Front 2

How do skeletal, smooth, and cardiac muscle differ?

Back 2

Arrangement of myofibrils
Capacity for regeneration
Neural regulation

Front 3

What are the traditional (3) groups of muscle?

Back 3

Skeletal
Smooth
Cardiac

Front 4

Basic Idea of Skeletal muscle:

Back 4

striated
controlled voluntarily
Multinucleated

Front 5

Basic Idea of smooth muscle:

Back 5

which is non-striated and involuntary in action

Front 6

Basic Idea of cardiac muscle:

Back 6

multinucleated
striated
involuntary

Front 7

What intracellular things allow for contraction to occur?

Back 7

intracellular contractile filaments, composed primarily of actin and myosin

Front 8

What is the epimysium?

Back 8

Epimysium surrounds the entire muscle

Front 9

What is the perimysium?

Back 9

Perimysium surrounds the bundles

Front 10

What is the endomysium?

Back 10

Endomysium surrounds individual muscle fibers

Front 11

Muscle fibers are composed of many cells. What are they called?

Back 11

Myoblasts

Front 12

What are the satellite cells in muscle tissue?

Back 12

cells that lie under the basement membrane represent stem cells held in reserve.

Front 13

Within the muscle, what are the myofibrils?

Back 13

Myofibrils are intracellular contractile elements running longitudinally within the muscle fiber, and it is the registration of adjacent myofibrils that gives skeletal muscle its striated (banded) appearance.

Front 14

Are skeletal muscle fibers directly innervated?

Back 14

Yes.

Front 15

What is the basic unit of contraction in muscle fibers?

Back 15

Sarcomere

Front 16

Describe the A Band:

Back 16

dark staining, bisected by an H band. Except for the H band, it contains both thick and thin filaments. The thick filaments are composed of myosin.

Front 17

Describe the I Band:

Back 17

light staining, bisected by a thin Z line. The I band contains only thin filaments composed of actin, tropomyosin and troponin.

Front 18

Describe the Z line:

Back 18

contains alpha-actinin and vinculin, that anchor the actin filaments.

A sarcomere runs from one Z line to the next.

"Ze 'Z' line seperates Ze sarcomeres"

Front 19

In a sarcomere what are the thick and thin filaments?

Back 19

Thick - Myosin
Thin - Actin

Front 20

What is a motor endplate?

Back 20

The region where the motor neuron terminates at the muscle fibers.

Front 21

What is a motor unit?

Back 21

A motor nerve and all muscle fibers it innervates.

Front 22

What is released at the motor end plate and where is it released?

Back 22

Acetylcholine is released into the sarcolemma (muscle plasma memrane) and then spread to the T-tubules

Front 23

What are the T-tubules?

Back 23

Depolarization spreads through the T-tubules to reach the inner fibers.

The depolarization causes Ca release from the sarcoplasmic reticulum.

Front 24

What is muscle tone?

Back 24

The continous balance between relaxed and contracted. No muscle is ever completely relaxed.

Front 25

What do muscle spindles do?

Back 25

Provide information that leads to maintanence of muscle tone.

They are particularely heavy in units requiring fine motor control.

Front 26

What are muscle spindles composed of?

Back 26

Modified skeletal fibers called intrafusal fibers

Front 27

Describe nuclear chain vs. nuclear bag fiber:

Back 27

Bag - Centrally located nucleous

Chain - Spread out nucleous

Front 28

Describe how muscle spindles work:

Back 28

Sensory nerve endings continuously monitor the degree of stretching of these muscle fibers, and as they lengthen, i.e. they stretch because the main muscle mass is relaxing, impulses are relayed to the spinal cord. These impulses lead to the reflex activation of alpha motor neurons in the ventral horn that cause the main muscle to contract. This is also the physiological mechanism involved in the "stretch reflex".

Front 29

What motor neurons regulate the spindle fibers?

Back 29

gamma motor neurons

Front 30

Describe the smooth muscle cell:

Back 30

spindle shaped
smaller than skeletal fiber
single, central nucleous
no orderly arrangement of fibrils (no striations due to random placement of actin and myosin 'threads')

Front 31

What can smooth muscle secrete?

Back 31

Smooth muscle cells also synthesize and secrete collagen, elastin and proteoglycan

Front 32

Can smooth muscle divide?

Back 32

Yes

Front 33

Can Skeletal Muscle divide?

Back 33

i dunno...can it?

Front 34

Can cardiac muscle divide?

Back 34

No

Front 35

In smooth muscle, does contraction require innervation?

Back 35

No, self regulation or drone via autonomic

No direct innervation and no T-tubules

Front 36

In smooth muscle, how is the signal for contraction spread from cell to cell?

Back 36

gap junctions

Front 37

How is smooth muscle contraction initiated?

Back 37

Via Ca flux.

Differs than skeletal and cardiac

Front 38

How many nuclei do cardiac cells have?

Back 38

(2) or more

Front 39

How are cardiac cells joined together?

Back 39

a branching network via intercalated discs

Front 40

What (3) types of junctions exist at the intercalated disks?

Back 40

Desmosomes that transmit tension from one cell to the next.
Adhering junctions that are similar to the zonula adherens between epithelial cells.
Gap junctions that provide electrical continuity between adjacent cells.

Front 41

Why is cardiac muscle striated?

Back 41

Less so in comparison to skeletal.

Myofibrils contribute a striated appearance to this muscle, although the striations are less distinct than in skeletal muscle. A and I bands and Z lines can be seen and the mechanism of contraction is similar to that of skeletal muscle.

Front 42

What are the two parts of a muscle?

Back 42

Fleshy Fascia

and

Tendon

Front 43

Within a muscle, what are the two attachment ends called?

Back 43

origin

and

insertion

Front 44

What protein in muscles is the cause of muscular distrophies?

Back 44

Dystrophin holds actin to the cytoskeletal elements and is missing in some diseases

Front 45

Label

Back 45

Good

Front 46

Label

Back 46

Good

Front 47

Label

Back 47

Good

Front 48

Label

Back 48

Good

Front 49

Label

Back 49

Good

Front 50

Label

Back 50

Good

Front 51

Label

Back 51

Good

Front 52

Label items within smooth muscle cell

Back 52

Good