Muscle Tissue Flashcards Preview

S1 Anatomy > Muscle Tissue > Flashcards

Flashcards in Muscle Tissue Deck (37):
1

muscle tissue embryological origin

mesoderm

2

muscle tissue types

skeletal
cardiac
smooth

3

skeletal muscle
-characteristics (2)
-type of contraction
-appearance

characteristics
-striated
-voluntary
strong, quick discontinuous contraction
appearance
-long, cylindrical peripherally located nuclei
-multinucleated with cross-striations

4

cardiac muscle
-type of contraction
-appearance

strong, quick continuous (involuntary) contractions
appearance
-cross-striations
-branched
-end-to-end contact = intercalated discs

5

smooth muscle
-type of contraction
-appearance

weak, slow (involuntary) contractions
appearance
-collections of fusiform cells (do not show cross-striations)

6

muscle tissue is encased by... (broad term)

connective tissue

7

connective tissue network around muscle
-function
-types

function
-important for transmission of contractile forces through the entire muscle
-necessary since individual fibers don't extend entire length
types
-epimysium
-perimysium
-endomysium

8

epimysium
-type of CT
-location

dense irregular CT
surrounds entire muscle

9

perimysium
-type of CT
-location

thin septa of loose CT
separates and surrounds individual bundles of muscle fibers

10

endomysium
-type of CT
-location
-what is a unique function?

fine connective tissue
surrounds individual fibers, mostly basal lamina and reticular fibers
unique function
-carries capillaries along and through entire muscle

11

myotendinous junction
-composition
-inserts where?

collagen fibers of regular dense connective tissue
insert into endomysium

12

striated muscle components (4)

myoblasts
myotubes - primary, secondary
muscle - primary, mature
satellite cells

13

satellite cell function

allow for some regenerative capability

14

regenerative capability of the 3 types of muscle tissue

cardiac
-none
skeletal
-few satellite cells (limited production of myoblasts)
--development of muscle fiber
--"repair" of muscle is thus by hypertrophy of remaining muscle fibrils
smooth
-highly mitotic

15

muscle spindle
-location
-arrangement
-attached to...

location
-within skeletal muscles
arranged in parallel with the muscle fibers
attached to
-CT coverings of perimysium and endomysium

16

what will change the length of the muscle spindle

any change in length of the CT covering during muscle contraction or stretch

17

spindle responds to...
-what structures allow this response

responds to changes in length of the muscle
structures that allow this
-sensory endings located within an encapsulated area
-small muscle fibers positioned at the ends of the receptor area
--allow for "resetting" of the sensitivity of the muscle spindle

18

muscle spindle receptors are designed to respond to either...

dynamic (phasic) stretch
static (tonic) stretch

19

muscle spindle endings that respond to dynamic stretch
-rate of adaptation
-activity length
-what do they encode?

rapidly adapting
activity is short-lived
encode
-velocity of stretch
-duration of change

20

muscle spindle endings that respond to static stretch
-rate of adaptation
-function
-duration of respose

slow-adapting receptors
purpose
-maintain signaling of a stretch that is maintained
respond over time (long response)

21

how is the sensitivity of muscle spindle receptors altered?

via selective control by gamma motor neurons

22

what is a gamma motor neuron?

small motor neuron specific to muscle fibers within the muscle spindle

23

golgi tendon organ (GTO)
-location
-receptors responsible for..

located within the tendinous attachment of a muscle to bone
responsible for encoding tension within the tendon

24

in terms of where the encoded information is coming from, what is the difference between muscle spindles and GTOs?

muscle spindles
-encode information at muscle level
GTO
-encode information at tendon level

25

GTOs
-functions

signal change in tension (resistance to the force of contraction)
capable of signaling a response to excess tension as a protective mechanism

26

when a PT taps the patellar tendon, what is happening and what structures are causing change?
-what is the reflex that occurs called?

what is happening
-short instantaneous stretch of quadriceps
muscle spindle is being stimulated
little change to GTO since little tension is created
reflex called
-deep tendon reflex (DTR)

27

what reflex is the DTR sometimes confused with (ie they're not the same)

stretch reflex
-aka muscle stretch reflex/myotatic reflex

28

cardiac muscle characteristics (3)

striated
-similar to skeletal muscle
branched cells
-attached to adjacent cell by intercalated disc
single or double centrally located nuclei

29

intercalated disc
-composition and function of each part

zonula adherens
-anchoring of actin fibers, similar to z-line
macula adherens (desmosomes)
-anchor cardiac cells together
gap junctions
-on longitudinal plane of uneven intercalated discs
-give ionic continuity of side-to-side cells

30

t-tubule system
-presence compared to in skeletal muscle
-represented as...

present but not as regular as in skeletal muscle
represented as diads
-t-tubule and only one sarcoplasmic reticulum

31

smooth muscle
-characteristics (6)

fusiform cells
non-striated
no T-tubule system
contraction initiated by Ca2+ (different mechanism than striated muscle)
Ca2+ is bound by calmodulin
contraction can be regulated by changes in cAMP levels

32

fusiform cells (smooth muscle) characteristics

encased in basal lamina and reticular fibers
centrally located nucleus (single)

33

what is calmodulin

calcium binding protein that activates myosin in smooth muscle

34

an increase in cAMP levels results in...

phosphorylation of myosin
-muscle then contracts

35

what is present in the smooth muscle of organ systems that is not present in the smooth muscle of other areas
-what is the purpose

gap junctions
-muscles contract together, so they function as a unit (syncytium)

36

what is one reason (apart from synchronized contraction) for having gap junctions in smooth muscle?

there is little innervation in visceral smooth muscle such as the small intestine
gap junctions allow the nervous activation or message to be spread cell to cell

37

what is a location with rich innervation of smooth muscle?

iris of the eye (multi-unit smooth muscle)