Muscles

Question 1

Muscle

Answer 1

Contractile
Morphology - smooth, striated
Activity - voluntary, involuntary
Prefix - sarco (flesh) or myo-

Question 2

Muscle definitions

Answer 2

1. ) a tissue type

2. ) a specific mass of muscle tissue with an origin, insertion, and action

Question 3

Myofiber

Answer 3

Individual muscle cell

Question 4

Myofibril

Answer 4

Contractile elements within a myofiber

Question 5

Muscle Morphology

Answer 5

• can be flattened or cylindrical
• arrangement of myofibers determines mobility/dexterity
• epimysium, perimysium,
  endomysium

Question 6

Epimysium

Answer 6

Upon, outermost layer

- connective tissue layer (fascia) around individual muscle

Question 7

Perimysium

Answer 7

Connective tissue bundles that run between muscle fascicle

-groups of many myofibers

Question 8

Endomysium

Answer 8

Surrounds each individual myofiber (individual cell)

- will not be able to see grossly, difficult to make out histologically

Question 9

Myofiber morphology

Answer 9

• elongated
• frequently multi-nucleated
• filaments or fibrils (contractile elements)
  - -> actin, thin
  - -> myosin, thick (stains darker on electron micrograph)

Question 10

Smooth muscle

Answer 10

Found on viscera

–> intestines, blood vessels, bronchi

Question 11

Striated muscle

Answer 11

Found in heart and skeletal muscle

Question 12

Voluntary

Answer 12

Skeletal muscle

Question 13

Involuntary

Answer 13

Cardiac and visceral muscle

Question 14

Skeletal muscle is ____ and ____

Answer 14

Voluntary, striated

Question 15

Viscera is ____ and ____

Answer 15

Involuntary, non-striated

Question 16

Cardiac is ____ and _____

Answer 16

Involuntary, striated

Question 17

Skeletal muscle

Answer 17

• Multi-nucleated, peripheral
• Acts as syncytium
• Red, white, intermediate (gross)
• Twitch or contractile speed (fast or slow)

Question 18

Skeletal muscles can regenerate because they _____

Answer 18

Have multiple nuclei located in the periphery

Question 19

Type 1 muscle fiber

Answer 19

• –> Slow, oxidative
• Many mitochondria
• Large amount of myoglobin and cytochrome
• Slow twitch = fatigue resistant

Question 20

Where are type 1 muscle fibers found?

Answer 20

Mammal limbs, migratory bird breast, marathon runners

Question 21

Type 2a muscle fiber

Answer 21

• -> Fast, oxidative glycolytic
• Many mitochondria, much myoglobin
• Abundant glycogen
• Capable of anaerobic function (glycolysis)
• Fast twitch = fatigue resistant

Question 22

Type 2b muscle fiber

Answer 22

• -> Fast, glycolytic fibers
• Large fibers, “pink”
• Less myoglobin and mitochondria than types 1 and 2a
• Much glycogen
• Fast twitch fatigue prone motor units
• High lactic acid production

Question 23

Type 2a fibers are found in _____ and type 2b fibers are found in ____

Answer 23

Gazelles, cheetas

Question 24

Myofibrils

Answer 24

Bundles of myofilaments (actin, myosin)

• Provide striations
• Sarcomere: Z line to Z line

Question 25

Sarcomere components

Answer 25

- A band: dark, mostly myosin, center of sarcomere - I band: light, mostly actin - M line: center of A band, point of myosin attachment - Z line: actin filaments attach between adjacent sarcomeres - H band: between actin filaments

Question 26

Muscle contraction (sarcomere component)

Answer 26

Myofilaments remain the same length - Increase interdigiation - H and I zones get smaller, A band remains

Question 27

Muscle contraction regulation

Answer 27

Controlled by calcium! - Sarcoplasmic reticulum (cisterna, holds calcium) - Transverse tubular system - Tropomyosin, troponin, etc

Question 28

Transverse tubules

Answer 28

Invagination of the plasma membrane that causes calcium release upon depolarization

Question 29

Neuromuscular junction

Answer 29

- Axon and myofiber - -> motor endplate (synapse) - neuron + myofiber = motor unit - Acetyl choline = neurotransmitter

Question 30

Cardiac muscle

Answer 30

- Striated, involuntary - Central nuclei - Intercalated disks - Spontaneous rhythmic contraction - Permanent cells (scar tissue formation upon death)

Question 31

Intercalated disks

Answer 31

Where cardiac cells join - tightly adhered - NOT found in skeletal muscle!

Question 32

Smooth muscle

Answer 32

- Elliptical, fusiform cells - No cross-striations - Actin/myosin contractile elements - No T tubular system - Involuntary

Question 33

What are the intermediate filaments of actin/myosin

Answer 33

Desmin and vimentin

Question 34

Can smooth muscle contract rapidly?

Answer 34

No, lacks T tubular system

Question 35

Leiomyo

Answer 35

Prefix for smooth muscle

Question 36

Involuntary components of smooth muscle

Answer 36

- Autonomic control (epi, NE, Ach) - Calcium --> calmodulin --> myosin - Stretch

Question 37

What type of contraction does smooth muscle perform?

Answer 37

Sustained contraction - aka latch state - slow, prolonged

Question 38

Where is smooth muscle located?

Answer 38

GI, bronchioles, vessels, repro

Question 39

Skeletal summary

Answer 39

- Striated - Voluntary - Peripheral nuclei - 1, 2a, 2b - AcH

Question 40

Cardiac summary

Answer 40

- Striated - Involuntary - Central nuclei - Intercalated disks - AcH - slows the heart - NE - increases heart rate and contractility

Question 41

Smooth summary

Answer 41

- No striations - Involuntary - ANS - Sustain