Muscle Tissue

Question 1

Cardiac muscle

Answer 1

• short, branched, and striated (usually have one nucleus)
• cells connected by intercalated discs
• have a pacemaker
• are involuntary
• can not regenerate

Question 2

intercalated discs

Answer 2

where cardiocytes interlock and contain the gap junctions permit electrical coupling of cells

Question 3

what is important about the nervous system on the pacemaker cells of the cardiac muscle

Answer 3

the nervous system can alter the rate in which the pace maker cells fire

Question 4

smooth muscle

Answer 4

• short spindle shaped cells and non striated (usually one central nucleus)
• small cells with tapered ends
• can regenerate
• in the walls of blood vessels, digestive tract, urinary tract etc
• can move things, and regulates the diameter of blood and respiratory vessels

Question 5

skeletal muscle

Answer 5

• long, cylindrical striated cells with multiple nuclei

- can regenerate with aid of satellite cells

Question 6

four functions of skeletal muscle

Answer 6

1. moves/stabiles the position of the skeleton
2. guards the entrances and exits to the digestive, respiratory and urinary tract
3. generates heat
4. protects internal organs

Question 7

excitability

Answer 7

ability to respond to stimulation

Question 8

contractility

Answer 8

the ability to shorten actively and exert a pull or tension that is harnessed by connective tissue

Question 9

extensibility

Answer 9

the ability to contract over a range of resting lengths

- for example: muscle cell can be stretched to several times its original length and still contract when stimulated

Question 10

elasticity

Answer 10

the ability of a muscle to return to its original length

Question 11

fascicles

Answer 11

this is a group of muscle fibers

is surrounded by perimysium

Question 12

muscle fiber

Answer 12

• this is another term for a muscle cell
• long and cylindrical and span the entire length of the muscle
• this is surrounded by endomysium

Question 13

myofibrils

Answer 13

cylindrical structures extending the entire length of the muscle fiber

Question 14

myofilaments

Answer 14

• actin and myosin proteins

- organized into repetitive groupings of sacromeres that extend the length of the myofibril

Question 15

epimysium

Answer 15

surrounds the entire muscle

Question 16

perimysium

Answer 16

surrounds the fascles

Question 17

endomysium

Answer 17

surrounds the muscle fibers

Question 18

actin

Answer 18

this is the thin filament

Question 19

myosin

Answer 19

this is the thick filament

Question 20

sarcomere

Answer 20

this is how myofilaments are organized

-when many shorten together the muscle as a whole contracts

Question 21

neuromuscular junction

Answer 21

this is where the motor neuron meets the muscle fiber

-where innervation occurs

Question 22

motor unit

Answer 22

• single motor neuron and the muscle fibers it controls.
• it can innervate multiple muscle fibers
• the more muscle fibers it innervates the larger the motor unit is and the less individual/fine control the body has over it

Question 23

all or nothing principal

Answer 23

the muscle fiber contracts completely or none at all

-all of the muscle fibers in one motor unit will contract or non at all

Question 24

what has to happen is an area with small motor units wants to have a large coordinated movement?

Answer 24

Many motor units need to be signaled at once.

Question 25

where are small motor units typically at?

Answer 25

-eyes, hands, etc

Question 26

Slow oxidative Fibers (SO)

Answer 26

• these use oxygen as fuel
• these can contract for long periods of time
• these are aerobic and used for endurance
• have the greatest number of capillaries (blood supply)

Question 27

fast oxidative fibers (FO)

Answer 27

these are intermediate fibers

Question 28

Fast glycolytic fibers (FG)

Answer 28

• these are anaerobic, instantaneous power

- not for long periods of time

Question 29

Every muscle has what type of fiber

Answer 29

every muscle has all three types of fibers but the ratio changes depending on which muscle you are looking at
-additionally different people will have different ratios when looking at the same muscle on both

Question 30

muscle atrophy

Answer 30

this is a reduction in muscle size, tone, and power

-can be caused by lack of stimulation and happens with aging

Question 31

muscle hypertrophy

Answer 31

• this is the increase of the size of the muscle fiber.
• the fiber itself gets bigger by the addition of more myofibrils and myofilaments but there is NOT an increase in the number of fibers.

Question 32

What are the four main fascile arrangements?

Answer 32

• parallel
• convergent
• pennate
• circular

Question 33

Parallel fibers

Answer 33

• all fibers run in one direction

ex. biceps, abs

Question 34

convergent fibers

Answer 34

fanned out at the origin but converge at the tendon
-fibers run In different directions and different fibers have different functions due to the different angle and arrangement

Question 35

pennate fibers

Answer 35

-these have fibers entering a tendon at an angle
-can be unipennate (one angle), bipennate (two angles),
and multipennate (many angels)

Question 36

what is the benefit of being multipennate

Answer 36

this gives a larger cross-sectional area and increases the strength of the muscle.

Question 37

circular fibers

Answer 37

there are used to make sphincters