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Chapter 9: Muscular System
Skeletal Muscle Tissue and Muscle Organization
60
Anatomy
Undergraduate 1
10/16/2011

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Term
What are the 3 types of muscle tissue
Definition
  1. Skeletal Muscle
  2. Cardiac Muscle
  3. Smooth Muscle
Term
Skeletal Muscle
Definition
moves the body by pulling on bones of the skeleton
Term
Cardiac Muscle
Definition
pushes blood through the arteries and veins 
Term
Smooth Muscle
Definition
smooth muscle tissues push fluids and solids along the digestive tract
Term
What 4 basic properties do all muscle types share?
Definition
  1. Excitability
  2. Contractibility
  3. Extensibility
  4. Elasticity
Term
Excitability
Definition
ability to respond to stimulation
Term
Contractibility
Definition
ability to shorten actively and exert a pull or tension
Term
Extensibility
Definition
ability to continue to contract over a range of resting lengths
Term
Elasticity
Definition
the ability of a muscle to rebound toward its original length after a contraction
Term
What are the functions of skeletal muscle?
Definition
  1. produce skeletal movement
  2. maintain posture and body position
  3. support soft tissues
  4. regulate entering and exiting of material
  5. maintain body temperature
Term
Epimysium
Definition
dense irregular connective tissue, surrounds the entire skeletal muscle, saran wrap; separates the muscle from surrounding tissues and organs
Term
Perimysium
Definition
connective tissue fibers that divide the muscles into fascicles, groups of muscle cells
Term
Endomysium
Definition
reticular fibers that surrounds each skeletal muscle fiber
Term
What are the 2 functions of the Endomysium?
Definition
  1. binds each muscle fiber to its neighbor
  2. supports capillaries that supply fibers
Term
Tendons
Definition
made up of all three fibers (collagen, reticular, elastic) provide an extremely strong bond and any contraction of the muscle exerts a pull on the attached bone or tissue
Term
Aponeurosis
Definition
tendons that form thick, flattened sheets
Term
Sarcolemma
Definition
muscle cell membrane
Term
sarcoplasm
Definition
cytoplasm, or sarcoplasmic reticulum
Term
What is Reticulum?
Definition
  • network of tubules, vesicles, and cisternae within cells
  • stores calcium ions needed for muscle contraction
Term
Skeletal Muscle fibers differ from typical cells:
Definition
  • very large
  • multinucleated
  • transverse tubules
Term
MYOFIBRILS=MUSCLE FIBER=MUSCLE CELL
Definition
long, cylindrical, multinucleated
Term
Myofilaments
Definition

protein filaments

(actin, myosin)

Term
Actin
Definition
thin filaments
Term

Myosin

Definition
thick filaments
Term
Sarcomeres
Definition
actin and myosin filaments organized in repeating units
Term
Z line
Definition

open meshwork of proteins, at either end of the sarcomere

[image]

Term
M line
Definition

where myosin come together, network of proteins that link the thick filaments

[image]

Term
I band
Definition

only made up of actin, length of actin, region between A bands

[image]

Term
A band
Definition

length of myosin, (middle of sarcomere)

[image]

Term
H band
Definition

thick myosin filaments only

[image]

Term
What gives the muscles their banded appearance?
Definition
corresponding bands of individual sarcomeres
Term
What are the smalles FUNCTIONAL units of the muscle fiber?
Definition
Sarcomeres
Term
What is responsible for the contraction of muscle fibers?
Definition
interactions between the thick and thin filaments of the sarcomeres
Term
zone of overlap
Definition

where thin filaments pass between thick filaments

[image]

Term
What 2 proteins are contained in the thin filaments?
Definition
tropomyosin and troponin
Term
What happens whenan influx of calcium ions enter the sarcoplasm?
Definition
  • Calcium bonds to troponin
  • troponin covers and moves tropomyosn
  • allows myosin to bind with actin
Term
Tropomyosin
Definition
covers active sites on actin, precenting actin-myosin interaction
Term
Troponin
Definition
holds the tropomyosin in place
Term
Sliding Filament Theory
Definition
when myosin heads bind to active sites on actin filaments
Term
How is ATP used in a muscle contraction?
Definition
  • the breakdown of ATP "cocks" the myosin head and prepares it for binding on active site
  • ATP must bond to the myosin head for it to detach and "re-cock" for another cycle
Term
What happens at the neuromuscular juntion?
Definition
  • The synaptic terminal at the end of the axon is full of synaptic vesicles filled with Ach
  • Ach when realease binds to receptor sites on the motor end plate initiating a change in transmembrane potential
  • This change generates action potential
Term
Synaptic cleft
Definition
  • a narrow space between the synaptic terminal and the motor end plate
  • contains enzyme AChE which breaks down ACh
Term
Motor Unit
Definition
all of the muscle fibers controlled by a single motor neuron
Term
Muscle twitch
Definition
a single momentary contraction in response to a single stimulus
Term
Muscle Tone
Definition
some motor units are always contracting and producing a resting tension in a skeletal muscle
Term
Hypertrophy
Definition
enlargement of the stimulated muscle
Term
Muscle atrophy
Definition
the reduction in muscle size and tone due to lack of stimulation on a regular basis
Term
Fast fibers
Definition
  • supportd by anaerobic glycolysis, does not require O2
Term
Slow fibers
Definition
  • produce ATP by aerobic metabolism
  • red because they contain myoglobin
Term
Intermediate fibers
Definition
similar to fast fibers but have more mitochondria, increased capillary supply and greater resistance to fatigue
Term
Parallel Muscle
Definition
the fascicles are parallel to the long axis of the muscle; most skeletal muscles are parallel muscles
Term
Convergent Muscles
Definition
the muscle fibers are based over a broad area, but all the fibers come together at a common attachment site; fan out like a broad trangle
Term
Pennate Muscles
Definition

one or more tendons run through the body of the muscle and the fascicles form an oblique angle to the tendon

  1. unipennate- iff all muscle cells are founf on the same side of the tendon
  2. bipennate- muscle fibers on both sides of tendon
  3. multipennate- if the tendon branches within the muscle
Term
Circular Muscles
Definition
fibers are concentrically aranged around an opening or recess
Term
Origin
Definition
where a muscle begins
Term
Insertion
Definition
where a muscle ends
Term
Prime movers
Definition
muscles whose contractions are chiefly responsible for producing a movement
Term
Synergists
Definition
assist the prime mover in performing that action
Term
Antagonists
Definition
muscles whose actions oppose that of the agonist
Term
What happens to muscles as the body ages?
Definition
  • general reduction in size and power of all muscle tissues
  • tolerance for exercise decreases
  • ability to recover from muscular injuru decreases
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