Muscle Tissue I and II

Question 1

what are the 3 types of muscle?

Answer 1

skeletal, cardiac and smooth

Question 2

what are other terms used for muscle fibers?

Answer 2

muscle cell, myocyte

Question 3

what do muscle fibers do? what are they surrounded by?

Answer 3

produce force, movement and heat

surrounded by connective tissue matrix, bounded by external lamina

MUSCLES ONLY PULL CANNOT PUSH

Question 4

what makes up muscle fibers?

Answer 4

-sarcolemma —> plasma membrane

-sarcoplasm –> cytoplasm

-sarcoplasmic reticulum (SR) –> sER

Question 5

what is contraction?

Answer 5

the interaction of cytoplasmic protein chains (myofilaments)

actin and myosin

Question 6

what causes conformational change?

Answer 6

Calcium

causes actin and myosin to move relative to each other

Question 7

what types of muscle are striated?

Answer 7

skeletal and cardiac

Question 8

what type of muscle makes up NONstriated muscle?

Answer 8

smooth muscle

Question 9

describe some general information about skeletal muscle?

Answer 9

-has multinucleated adult cells —> b/c they join together
-has ABUNDANCE of MITOCHONDRIA, GLYCOGEN, MYOGLOBIN

Question 10

how is skeletal muscle organized?

Answer 10

tendon –> muscle –> fascicle (muscle fiber bundles) –> muscle fiber –> myofibrils

myofibrils: long rows of myofilaments (contractile thread)

Question 11

what are the dark bands? the light one? what is the dark line in the light band?

Answer 11

dark bands: A bands
light bands: I bands
dark line: Z disk/Z line

Question 12

what makes up the sarcomere?

Answer 12

area from one Z disk to another Z disk

is the smallest contractile unit

Question 13

what is the sliding filament theory?

Answer 13

the Z lines are brought closer together as myofilaments slide past each other

IMPORTANT: myofilaments do not change length

Question 14

what are transverse tubules (t tubules)?

Answer 14

extension of plasma membrane so the rods inside can receive excitement

Question 15

what are triads?

Answer 15

2 terminal cisternae + 1 t tubule

are located at junction of A and I bands

Question 16

what does the all or none principle of contraction mean?

Answer 16

every one (need to specify) will contract or none will

Question 17

what is a motor unit?

Answer 17

motor neuron and the muscle fiber it innervates

Question 18

what is the synonymous name for a terminal bouton?

Answer 18

synaptic knob

Question 19

what does the golgi tendon organ do?

Answer 19

keeps track of how much contraction is happening and if “bad” things are happening

Question 20

what do muscle spindles do?

Answer 20

are non contractile

keeps track of what is going on in the muscle

PROPRIOCEPTION

Question 21

what is limited hyperplasia in skeletal muscle?

Answer 21

one response to stress
adding cells

-no mitosis
-satellite cells may give rise to myoblasts if external lamina is intact

Question 22

what is the primary response in skeletal muscles to stress?

Answer 22

HYPERTROPHY - cells that you have get bigger

myocytes enlarge by addition of proteins
satellite cells fuse with muscle fibers

Question 23

what are the general characteristics of cardiac muscle?

Answer 23

STRIATED SARCOMERES

autorhythmic contractions –> beats by itself
-modulated by autonomic neurons
-propagated by gap junctions (same as epithelial)

HAS SINGLE, CENTRALLY LOCATED NUCLEUS —> cardiac muscle fibers branch

Question 24

what are intercalated disks and why are they important?

Answer 24

dark-staining line where intercellular junctions occur

HOW YOU CAN TELL ITS CARDIAC AND NOT SKELETAL

Question 25

describe the general intercalated disk characteristics

Answer 25

EM: very irregular

transverse portion (where the strength comes from): fascia adherens and desmosomes

longitudinal portion: gap junctions and has less mechanical stress

Question 26

describe cardiac muscle fibers and the general characteristics?

Answer 26

can be branched or arranged in layers

mononucleated, central nucleus
have HIGH QUANTITY of mitochondria and myoglobin

intercalated discs with gap junctions

large t tubules, spare SR, source of calcium, diad at the Z disc, has sarcomeres and myofibrils

Question 27

how does cardiac muscle respond to stress?

Answer 27

hyperplasia is negligible

hypertrophy is in response to mechanical stressed (addition of proteins but no satellite cells)

Question 28

what happens to cardiac muscle in the event of an injury?

Answer 28

cell death and fibrosis (scar tissue)

b/c less contractile than before

Question 29

describe some general smooth muscle characteristics

Answer 29

-is found in hollow organs, blood vessels, dermis and respiratory passages

NO T TUBULES AND VERY LITTLE SR (calcium source —> mainly extracellular)

Question 30

what are calveolae?

Answer 30

membrane invaginations that facilitate intake of calcium

slowest contractions

Question 31

what is this? what shape is it?

Answer 31

smooth muscle

single, central nucleus

NOT STRIATED

Question 32

why are there crisscross patterns of the myofilaments in smooth muscle?

Answer 32

facilitates contraction of fusiform shape

Question 33

where is actin anchored at in smooth muscle?

what does it do?

Answer 33

anchored at dense bodies

function similar to Z lines

stabilized by intermediate filaments

Question 34

what type of nucleus does smooth muscle have?

Answer 34

corkscrew nuclei —> cell twists as it contracts

Question 35

what are the two types of smooth muscle contraction?

Answer 35

1) multiunit contraction
2) single unit (unitary) contractoin

Question 36

what is multiunit contraction in smooth muscle?

Answer 36

-muscle functions as multiple units of cells
-each unit innervated by single ANS neuron
-no/few gap junctions

axon terminals in CT, no direct junction with muscle cells

Question 37

what is single unit (unitary) contraction in smooth muscle?

Answer 37

-all cells contract together as a single unit b/c cells linked by gap junctions
-contractions initiated by mechanical/chemical stimuli and modulated by ANS

-slow, energy efficient contractions

axon terminals in CT, no direct junction with muscle cells