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Human Anatomy > Ch. 10 Muscle and Tissue Organization > Flashcards

Ch. 10 Muscle and Tissue Organization Flashcards

1
Q

Properties of Muscular Tissue

A

electrical excitability, contractility, extensibility, elasticity

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2
Q

Structure of Skeletal Muscle

A
  • skeletal muscle bundle consists of a body (belly) connected by tendons to the skeleton
  • tendons are nearly avascular structure, composed of a parallel arrangement of collagen fibers at the ends of the muscle
  • tendon is an extension of three connective tissue layers that surrounds the different organizational levels of a skeletal muscle
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3
Q

Skeletal Muscle Connective Tissue Coverings

A
  • muscle bundles are surrounded by epimysium, dense irregular tissue
  • muscle fascicles (bundles) are surrounded by perimysium, transmits blood vessels
  • muscle fibers are surrounded by endomysium, reticular fibers, bind muscle fibers together
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4
Q

Deep Fascia

A
  • an expansive sheet of dense irregular connective tissue
  • separates individual muscles
  • binds together muscles with similar functions
  • forms sheaths to help distribute nerves, blood vessels, and lymphatic vessels
  • fill spaces between muscles
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5
Q

Microscopic Anatomy of a Skeletal Muscle Fiber

A
  • muscle fibers while very small in diameter, run the length of the muscle bundle and are usually measured in inches
  • muscle fibers are multinucleate, from before birth, and last a lifetime
  • muscle growth after being born is due to hypertrophy (increased cell size) rather than hyperplasia (increased cell numbers)
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6
Q

Filaments and the Sarcomere

A
  • myofibrils are made of thick filaments (myosin) and thin filaments (actin) which in turn are made of protein
  • these filaments are arranged in special compartments called sarcomeres (the functional unit of contraction)
  • the pattern of overlap of thick and thin filaments consists of zones and bands which cause the striated appearance of skeletal muscle
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7
Q

Muscle Proteins

A
  • myofibrils are built from 3 kinds of proteins
    Contractile Proteins: generate force during contraction by sliding past each other rather than literally shortening ex. actin and myosin
    Regulatory Proteins: help switch the contraction process on and off ex. troponin and tropmyosin (covers myosin bind receptors)
    Structural Proteins: keep thick and thin filaments in proper alignment, give the myofibril elasticity and extensibility, and link the myofibrils to the sarcolemma and extracellular matrix ex. M line (hold myosin in centre) and Z-disc (actin attaches)
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8
Q

Myosin

A
  • major component of thick filaments

- functions as a motor protein that achieves movement by converting the chemical energy into mechanical energy

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9
Q

Actin

A
  • major component of thin filaments
  • also contain the regulatory proteins, tropomyosin (covers binding site for myosin) and troponin (pull tropomyosin in or out)
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10
Q

Microscopic Structure of Skeletal Muscle Fiber

A

muscle fiber cell (myofibrils)
myofilaments (thick and thin- striations)
- dark A-Band, thick and thin filaments overlapping, myosin and actin, contract and relaxation
- light I-Band, contain only thin filaments, only actin, causes only muscle movement

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11
Q

Nerve and Blood Supply of Skeletal

A
  • most receive one nerve that supplies them with motor and sensory functions, other muscles receive multiple nerves
  • nerves typically enter a muscle with blood vessels as a unit called a neuromuscular bundle
  • these nerves carry both sensory and motor info
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12
Q

Somatic Motor Neurons

A
  • individual cells (neurons) that innervate skeletal muscle fibers are called
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13
Q

Neuromuscular Junction (NMJ)

A
  • is a point of near-contact between a somatic motor neuron and a skeletal muscle fiber
  • each muscle fiber has one NMJ, yet the axon of a somatic motor neuron branches out and form NMJs with many different muscle fibers
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14
Q

Motor Unit

A
  • one somatic motor neuron plus all the skeletal muscle fibers it stimulates is called a motor unit
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15
Q

Sliding Filament Mechanism Theory

A
  • During contraction of a muscle fiber:
    1. distance between Z-discs shortens (holds actin)
    2. distance between A- remains the same (overlap of thick and thin, myosin doesn’t move)
    3. distance between I- band shortens (only actin)
    4. distance between H-zone shortens (only myosin)
  • distance between 2 Z-discs is sacromere
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16
Q

Muscle Attachment Sites: Origin and Insertion

A
  • skeletal muscles cause movements by exerting force on tendons, which pulls on bones or other structures
  • articulating bones usually do not move equally in response to contraction
  • attachment of a tendon to the stationary bone is called the origin
  • attachment of the muscle’s other tendon to the movable bone is called the insertion
  • the action of a muscle are the main movements that occur during contraction (flexion or extension)
17
Q

Coordination among muscles

A
  • movements usually result from several skeletal muscles acting as a group, most skeletal muscles are arranged in opposing pairs at joints (ex. flexors vs extensors)
    Agonist: (prime mover) produces specific movement when it contracts (biceps brachii)
    Antagonist: is a muscle whose action opposes that of an agonist (triceps brachii would be antagonist)
    Synergist: is a muscle that assist the agonist or prime mover
18
Q

Muscle Fascicle Arragement

A
  • all muscle fibers are parallel to one another within a single fascicle
  • fascicles, however, form patterns with respect to the tendons
  • parallel (sternohyoid), fusiform, circular, triangular (pectoralias), pennate (uni, bi, multi)
19
Q

Cardiac Muscle Cells

A
  • striated, involuntary, branched, and uninucleate
  • intercellular connections points (intercalated discs) contain structural and electrical connections, called desmosomes and gap junctions
  • cardiac tissue is capable of autorhythmicity, an ability to spontaneously generate impulses that trigger contraction
20
Q

Smooth Muscle Tissue

A
  • composed of short muscle fibers that have a fusiform shape and single centrally located nucleus
  • thick and thin filaments are not precisely aligned so no visible striations or sarcomeres are present
  • Z discs are absent- thin filaments are attached to dense bodies by elements of the cytoskeleton
  • sarcoplasmic reticulum is sparse
  • transverse tubules are absent
  • contraction is slow, resistant to fatigue, and usually sustained for an extended period of time
  • takes longer than skeletal muscle to contract and relax
  • contraction is under involuntary control
21
Q

Functions of Muscular Tissue

A

Body movements, body stability, storing anf moving substances, heat production

22
Q

Sacrolemma

A

plasma membrane of a skeletal muscle fiber

23
Q

T Tubles

A

extensions of the sacrolemma that tunnel throughout the muscle fiber, are open to the outside, and filled with ISF

24
Q

Sacroplasma

A

cytoplasm of a skeletal fiber

Human Anatomy (24 decks)

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