Chapter 10: Muscle Tissue

Front 1

Properties of Muscle Tissue

Back 1

Excitability: Responsive to stimuli

Contractibility: stimulation = contraction

Elasticity: a contracted muscle cell recoils to its resting length

Extensibility: capable of extending in length

Front 2

Characteristics of Muscle Tissue

Back 2

Composed of four types of tissue: epithelial, connective, muscle, and nervous

Body Movement: when muscle contracts the bone moves

Maintenance of Posture: muscles stabilize joints and helps maintain posture

Temperature of Regulation: heat is produced

Storage an movement of materials

Support: support the walls of adomino pelvic wall

Front 3

Skeletal Muscle Composition

Back 3

composed of:

- numerous skeletal muscle fibers

- blood vessels

- nerves

- connective tissue sheers that surrond the muscle fibers and connective muscle to bone

Front 4

Fascicles

Back 4

bundles of muscles fibers

Front 5

Myofibrils

Back 5

cylindrical structures in the muscle fibers

Front 6

Connective Tissue Component

Back 6

- three layers of connective tissue

- Collagen

- Elastic Fibers

Front 7

Endomysium

Back 7

innermost connective tissue layer

-it is a delicate areolar connective layer that surrounds and electrically insulates each muscle fiber

Front 8

Perimysium

Back 8

surrounds the fascicles

- dense irregular connective tissue sheath of perimysium

- contains extensive arrays of blood vessels and nerves

Front 9

Epimysium

Back 9

surronds the whole skeletal muscle

- composed of dense irregular connective tissue

Front 10

Deep fascia

Back 10

an expansive sheet of dense irregular connective tissue that:

- separates individual muscles

- binds similar muscles with similar functions - ---- forms sheaths to help distribute nerves, blood vessels, and lymphatic vessels

Front 11

Superficial Fascia

Back 11

Outside later of deep facia that separates the muscle from the skin

- composed of areolar and adipose connective tissue

Front 12

Tendon

Back 12

attached the muscle to bone, skin, or another muscle

Front 13

Aponeurosis

Back 13

thin flattened sheet formed form tendon

Front 14

Origin

Back 14

the less mobile attachment of a muscle

Front 15

Insertion

Back 15

the more mobile attachment of muscle

Front 16

Blood Vessels

Back 16

deliver to the muscle fibers nutrients and oxygen need for production of ATP and remove waste products

Front 17

Voluntary Muscle

Back 17

controlled by voluntary nerocus system and stimulate smucle contraction

Front 18

Motor nuerons

Back 18

neurons that stimulate muscle contraction

Front 19

Axon

Back 19

nerve fiber that transmit a nerve impulse to a muscle fiber

Front 20

Sacrolema

Back 20

plasma membrane of a skeletal muscle fiber

Front 21

Sacroplasma

Back 21

cytoplasm of skeletal muscle fiber

- site of metabolic processes for normal muscle fiber activities

Front 22

T- tubules

Back 22

deep invaginations of the sacrolema that extend into the sacroplasma of skeletal muscle fibers as a network of thin membranous tubules

Front 23

Sacroplasma Reticulum

Back 23

Smooth ER in a muscle fiber

- stores calcium ions needed to initiate muscle contration

- runs perpendicular to the muscle fiber

Front 24

Terminal Cisternae

Back 24

expanded nerves of the Sacroplasma reticulum that are in contact with T- tubules

- quickly transport a muscle impulses form the sacrolemma through the entire muscle fiber

- reservers and specific sites for calcium ion release to intitate muslce contraction

Front 25

Triad

Back 25

terminal cisternae interact with T- tubules during muscle contraction and form this structure

Front 26

Myoblasts

Back 26

a group of embryonic cells that fuse to form single skeletal muscle fibers

Front 27

Satellite Cells

Back 27

myoblast that do not fuse during the fusion process to differentiate and assist in its repair and regeneration

Front 28

Myofibrils

Back 28

organized bundles of myofilaments

- cylindrical structures as long as the muscle fiber

- contain myofilaments responsible for muscle contraction

- during contraction they shorten

Front 29

Myofilaments Classification

Back 29

Thin and Think Filaments

Front 30

Thin filaments

Back 30

primary composed of two strands of protein actin twisted around each other to form a helical shape

- composed of actin, troponin, and tropomyosin

Front 31

Tropomyosin

Back 31

short, thin, twisted filament that covers small section of actin strands

- double stranded regulatory protein

Front 32

Troponin

Back 32

regulatory protein that holds tropomyosin in place and anchors to actin and provides binding cite for calcium

- when calcium binds to one of its subunits it changes shape

Front 33

Actin

Back 33

double stranded contractible protein

-form a bead like structure

Front 34

Thick Filaments

Back 34

about twice as large as thin filaments

- assembled from bundles of protein myosin

Front 35

Myosin

Back 35

consist of two strands:

- free globular head

- elongated tail

Front 36

Cross Bridges

Back 36

during contraction it is formed when think filaments bind with actin in the thin filaments

Front 37

A bands

Back 37

entire thick filament under the microscope

Front 38

I Bands

Back 38

contain thin filaments but no thick filaments

Front 39

Tintin

Back 39

filaments of an elastic protein

-play a role in elastic control of think filament assembly and passive stiffness generated in muscles

- found in thin filament

Front 40

H Zone

Back 40

a light central region in the A Band

- only thick filaments

- no thin filaments overlapping

- disappears when maximal contraction occurs

Front 41

M Line

Back 41

a thin transverse protein mesh work structure in the center of the H zone of a relaxed fiber

- serves as attachment site for thick filaments and keeps the thick filaments aligned during contraction and relaxation

Front 42

Z disc

Back 42

a thin transverse protein structure in the center of the I band that serves as an attachment site for thin filament ends

Front 43

Connectins

Back 43

are Z discs protein that anchor and interconnect the thin filament ends at either end of a sacromere

Front 44

Sacromere

Back 44

the distance from Z discs to the next adjacent Z discs

- think filaments are positioned at the center of sacromere

Front 45

Sliding Filament Theory

Back 45

when a muscle contracts, think and thin filaments slide past each other and the sacromere shortens

Front 46

Changes to sacromere in contraction

Back 46

- the width of the A band remains constant but the H zone disappears

- the Z discs in one sacromere move closer together

- Sacromere narrows and shortens in length

Front 47

Neuromascular junction

Back 47

point whree a motor nueron meets a skeletal muscle

Front 48

Synaptic Knob

Back 48

Expanded tip of the axon and houses Synaptic vesicles

Front 49

Synaptic vesicles

Back 49

small membrane sacs that are filled with ACh

Front 50

Motor end plate

Back 50

specialized region of the sarcolemma

- it has folds an indentations to increase the membranes surface area covered by the synaptic knob

Front 51

Synpatic Cleft

Back 51

is a narrow space seperating the synaptic know and the motor end plate

Front 52

ACH receptors

Back 52

in the motor end plate act like doors that normally are closed and ACh are the key to open the doors

Front 53

AChE

Back 53

reside in the synaptic cleft and rapidly breaks down molecule of ACh that re released in synoptic cleft

-stops stimulation

Front 54

Step 1: Muscle Contraction

Back 54

a nerve impulse causes ACh release at a neuromuscular junction. ACh binds receptors on the motor end plate, intiate muscle impulse

Front 55

Step 2: Muscle Contraction

Back 55

the muscle impulse spreads quickly along the sarcolemma and into the muscle fiber along the T- tubules membranes, causing calcium ions to be released into the sarcoplasm

Front 56

Step 3: Muscle Contraction

Back 56

Calcium binds to troponin, causing tropomyosin to move and expose active sites on actin. Myosin heads attach to the actin and form cross bridges

Front 57

Step 4: Muscle Contraction

Back 57

Myosin heads go through cyclic "attach pivot, detach, return" events as the thin filaments are pulled past the thick filaments. ATP is required to detach the myosin and complete the sequence. The sacromere shortens and the muscle contracts.

Front 58

Step 5: Muscle Contraction

Back 58

Calcium ions are moved back into the sarcoplasmic reticulum by the ATP driven ion pumps to reduce calcium concretion in the sarcoplasm, leading to relaxation. Termination of the muscle impulse results in the passive sliding of filaments back to their original state

Front 59

Motor Unit

Back 59

a single motor neuron and all the muscles fibers it controls

- the smaller the motor unit the finer the control

Front 60

All or None principle

Back 60

a muscle fiber either contracts completely or does not contract at all

Front 61

Muscle Tone

Back 61

the resting tension in a skeletal muscle

- stabilizes the position of bones and muscles

Front 62

Two types of muscle contraction

Back 62

Isometric and isotonic contraction

Front 63

Isometric contraction

Back 63

the length of the muscle does not change because the tension produced by this contacting muscle nerve exceeds the resistance

- not great enough to move the load

Front 64

Isotonic contraction

Back 64

the tension produced equal or it is greater than the resistance (load) and the muscle fibers shorten, resulting in movement

Front 65

Cocentric contractions

Back 65

actively shorten a muscle

Front 66

Eccentric contraction

Back 66

actively lengthen a muscle

Front 67

Slow fibers

Back 67

contract more slowly than fast fibers

- specialized to contribute contracting for extended period of time

- also called red fibers bc contain myoglobin

- have large amount of mitochondria

Front 68

Myoglobin

Back 68

globular, oxygen binding, reddish appearing protein is structurally related to hemoglobin

Front 69

Intermediate Fibers

Back 69

exhibit properties that are some where between those of slow fibers and fast fibers

- have a greater resistance to fatigue than slow

- proportion of fibers change with physical conditioning

Front 70

Fast Fibers

Back 70

large in diameter and they contain large glycogen reserves, densely packed myofibrils and relatively few mitochondria

- lack of myoglobin

- compose most of the body

powerful contraction bc they contain a large amount of sarcomeres

- vast quantities of ATP

Front 71

Slow Fibers Location

Back 71

dominate mainly back and calf muscles

Front 72

4 types of fascicle arrangement

Back 72

Circular, parallel, convergent, pennate,

Front 73

Circular Muscles

Back 73

concentrically arranged around an opening or recess

- contraction of the muscle closes of the opening

- ex: oris muscle that encircle the mouth `

Front 74

Parallel Muscles

Back 74

run parrallel to a long axis

- have a centrally body called a belly

- muscle shortens when contracts ans its body increases in diameter

- Ex: rectus abdominis, biceps, massetter

Front 75

Convergent Muscles

Back 75

widespread muscle fibers that converge on a common attachment site

Front 76

Pennate Muscle

Back 76

tendons and muscle resemble a large feather

- have one or more tendons extending through their body and fascicles are arranged at an oblique angle to the tendons

- three types

Front 77

3 types of Pennate muscles

Back 77

Unipennate

bipennate

multipennate

Front 78

Unipennate Muscles

Back 78

all the muscle fibers are on the same side of the tendon

Front 79

Bipennate Muscles

Back 79

muscle fibers on both sides of the tendon

Front 80

Mutlipennate Muscles

Back 80

branches of tendons within the muscle

Front 81

Atrophy

Back 81

wasting of tissue that results in a reduction of size, tone, and power

Front 82

Muscle hypertrophy

Back 82

an increase in muscle fiber size

- not an increase in muscle fiber

- results in more mitochondria, larger glycogen reserve, and increased ability to produce ATP

Front 83

First Class Lever

Back 83

has a fulcrum in the middle, between the effort and the resistance

Ex: antlanto occipital of the neck

Front 84

Second Class Lever

Back 84

resistance is between the fulcrum and the applied force

ex: Stands on toes

Front 85

Third Class Lever

Back 85

an effort applied between the fulcrum and the resistance

- most common in the body

- ex: in the elbow

Front 86

Agonist

Back 86

prime mover, is a muscle that contracts to produce a primary movement

Front 87

Antagonist

Back 87

muscle whose actions oppose to those of the agonist

Front 88

Synergist

Back 88

muscle that assist the agonist in performing its actions

- either contributes to the tension exerted lose to the insertion or stabilized the point of origin

Front 89

Cardiac muscles

Back 89

individual muscle cells are arranged in thick bundles within the heart

- have 1 or 2 nuclei

Front 90

Intercalated discs

Back 90

Y shaped branches were cardiac musle cells join

Front 91

Autorhythmic

Back 91

individual cells can generate a muscle impulse without nervous simulation

- dependent for their contraction upon calcium ions `

Front 92

Smooth Muscle

Back 92

composed of short muscle cells that have a fusiform shape

- have centrally located nucleus

- thin filaments are attached to dense bodies by elements of cytoskeleton

Front 93

Dense bodies

Back 93

small concentrations of proetin scattered through out the cytoplasm and on the inner face of sacrolema

Front 94

Stimulation of Smooth Muscle

Step 1:

Back 94

When calcium reaches the interstitial fluid:

1) Smooth muscle cells have a unique protein called myosin light chain. Calmodulin regulates the addition of phosphate to myosin chain

Front 95

Stimulation of Smooth Muscle

Step 2:

Back 95

2) although troponin is lacking in smooth muscle cells, cytoplasmic levels still regulate contractile activity when calmodulin binds to a protein called calesmo, which then regulates the movement of tropomyosin from the myosin binding sites in thins filaments

Front 96

Aging in Muscular system

Back 96

- loss of muscle mass is replaced either by adipose or fibrous tissue

- skeletal muscle fibers decrease in diameter

- muscle strength endurance is impaired

- number of satellite cells decrease

- less tension generated

- elasticity decreases