Muscular system Flashcards
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Scientific study of muscles
Myology
3 types of muscles
- skeletal muscle
- cardiac muscle
- smooth muscle
Striated and voluntary
Skeletal muscle
striated and involuntary
cardiac muscle
non-striated and involuntary
Smooth muscle
4 properties of muscular tissue
- electrical excitability
- contractility
- extensibility
- elasticity
Muscular tissue’s property to respond to stimulus
electrical excitability
muscular tissue’s property to shorten
contractility
muscular tissue’s property that allows it to be stretched
extensibility
Muscular tissue’s property to be able to recoil to original resting length
elasticity
Function of MS
- produce body movements
- stabilizing body positions
- storing and moving substances within the body
- thermogenesis
Attached to the bones and moves parts of the skeleton
SKELETAL MUSCLE
- Striated
- Voluntary
- Limited capacity for regeneration
SKELETAL MUSCLE
Alternating light and dark bands
Striated
Means Conscious control
Voluntary
- Small number of cells that can undergo cell division
Limited capacity for regeneration
Dense layer of connective tissue that surrounds entire muscle
Epimysium
Connective tissue that surrounds each fascicle
Perimysium
Delicate connective tissue (reticular fibers and basal lamina) that surrounds each muscle cell (fiber)
Endomysium
Histology of muscle
- cylindrical muscle fibers parallel to one another (elongated/cylindrical with blunt ends)
- Multi-nucleated (peripheral [at the sides])
What do you call the plasma membrane in muscles?
Sarcolemma
Invaginations of the sarcolemma
Transverse tubules
Cytoplasm for muscles?
Sarcoplasm
Where synthesis of ATP takes place
Glycogen
This binds O2 molecules
Myoglobin
Plays a role in muscle contraction
Sarcoplasmic reticulum
This is a filament
Myofibrils
Two types of myofibrils
Thick filament, thin filament
basic functional unit of striated muscle fibers; separated by Z discs
Sarcomeres
extends the entire length of the thick filaments.
- A band
center of each A band
H zone
end of each A band; contains the rest of the thin filaments
- I band
necessary for contraction to take place; delivered by a motor neuron
Muscle action potential
single motor neuron + the muscle fibers it stimulates
Motor Unit
synapse between a motor neuron and a skeletal muscle fiber
Neuromuscular junction (NMJ)
nerve cells that carry action potentials to muscle fibers
Motor neuron
end of nerve cell (axon)
Presynaptic terminal
muscle fiber membrane
Postsynaptic membrane
space between presynaptic terminal and postsynaptic membrane
- Synaptic cleft
- in presynaptic terminal
- store and release neurotransmitters
Synaptic vesicle
- chemicals that stimulate or inhibit a muscle
fiber - Ex. Acetylcholine
Neurotransmitter
3 sources of ATP production
- creatine phosphate
- anaerobic glycolysis
- aerobic respiration (oxidative phosphorylation)
– transfer of phosphate molecule to ADP to form new ATP molecule (15 seconds)
Creatine phosphate
use of glucose to yield 2 ATP(2 minutes)
Anaerobic glycolysis
prolonged activity (longer than half a minute) uses oxygen to produce ATP (36 ATP from each glucose molecule)
Aerobic respiration (oxidative Phosphorylation)
_____ is a brief contraction in response to a single
action potential
Twitch contraction
_____is the increased
strength of a contraction that occurs when a second stimulus arrives before the muscle has completely relaxed after a previous stimulus.
Wave summation
3 types of skeletal muscle fibers
- slow oxidative (SO) fibers (red fibers)
- fast oxidative-glycolytic (FOG) fibers
- fast glycolytic (FG) fibers (white)
Fiber high in myoglobin content, many blood capillaries, large mitochondria
Slow oxidative (SO) fibers (Red fibers)
Fiber in which aerobic respiration occurs
Slow oxidative (SO) fibers (Red fibers)
Largest fibers high myoglobin and glycogen content
Fast oxidative-glycolytic (FOG) fibers
- generates ATP by aerobic respiration
- increased intracellular glycogen level: generate ATP by anaerobic glycolysis
Fast oxidative-glycolytic (FOG) fibers
Fiber with low myoglobin content, high glycogen content
Fast glycolytic (FG) fibers (White)
fiber that generate ATP by glycolysys
Fast glycolytic (FG) fibers (White)
- Slow contraction speed.
- High resistance to fatigue.
- Primarily aerobic (oxidative) metabolism.
- Rich in mitochondria, capillaries, and myoglobin (which gives them a red color).
Type I Fibers (Slow-Twitch, Oxidative)
- Best suited for endurance activities like long-distance running or cycling.
- Soleus Muscle: Located in the lower leg, involved in maintaining posture and endurance activities like walking and standing.
- Erector Spinae: A group of muscles that run along the spine, responsible for maintaining posture and providing stability during slow, sustained activities
Type I Fibers (Slow-Twitch, Oxidative)
- Faster contraction speed than Type I fibers.
- Intermediate resistance to fatigue.
- Capable of both aerobic (oxidative) and anaerobic (glycolytic) metabolism.
- Moderate amounts of mitochondria, capillaries, and myoglobin.
Type IIa Fibers (Fast-Twitch, Oxidative-Glycolytic)
- Suited for activities that require both power and endurance, such as middledistance running.
- Quadriceps Femoris (especially the Vastus Lateralis):A muscle group in the thigh that is involved in activities requiring both power and endurance, such as cycling or running.
- Gastrocnemius Muscle (Intermediate Fibers): This muscle also has __________, contributing to both explosive and moderately sustained activities.
Type IIa Fibers (Fast-Twitch, Oxidative-Glycolytic)
- Fastest contraction speed.
- Low resistance to fatigue.
- Primarily anaerobic metabolism.
- Fewer mitochondria, capillaries, and less myoglobin (which gives them a lighter color)
Type IIb Fibers (Fast-Twitch, Glycolytic)
- Best suited for short, explosive movements like sprinting or weightlifting.
- Gastrocnemius Muscle (Fast-twitch Portion): Particularly the lateral head, which is involved in explosive movements like sprinting or jumping.
- Muscles of the Upper Limb (e.g., Biceps Brachii): Especially in activities like weightlifting, where quick, forceful contractions are required.
Type IIb Fibers (Fast-Twitch, Glycolytic)
2 types of muscle contraction
- Isotonic contractions
- Isometric contractions
- In this contraction, Myofilaments are able to slide past each other during contractions
- The muscle shortens
Isotonic contraction
In this contraction:
* Tension in the muscle increases
* The muscle is unable to shorten
Isometric contractions
type of muscle located in the heart
cardiac muscle
- Mono or Binucleated centrally located nucleus
- Exhibits branching (Cylindrical/elongated with branching ends)
Cardiac Muscle
- hold the muscle fibers together and allow muscle action potentials to quickly spread from one cardiac muscle fiber to another
Intercalated discs
Cardiac muscle tissue contracts when stimulated by its own
_____ fibers
autorhythmic
Cardiac muscle depends greatly on _______ to generate ATP.
aerobic cellular respiration
Type of muscle found in internal organs and blood vessels
Smooth muscle
- found in the walls of hollow viscera and of small blood vessels
Visceral (single-unit) smooth muscle tissue
found in large blood vessels, large airways to the lungs, arrector pili muscles, and the eye
Multiunit smooth muscle tissue
Contraction and relaxation longer in ______
smooth muscle
__________ is a state of continuous partial contraction of smooth muscle tissue
Smooth muscle tone
Muscle that is fusiform in shape
smooth muscle
3 parts of a muscle
- origin
- belly
*insertion
- Proximal fixed
attachment - nonmovable end
origin
- widest portion
- middle
belly
*Distal movable attachment
* movable end
Insertion
7 muscular forms/shape
- fusiform
- quadrate
- triangular
- unipennate
- bipennate
- longitudinal
- multipennate
The greater the length of muscle fibers, the ____ the range of motion
wider
The greater the number of muscle fibers, the ___and ____ the action of the muscle
greater, more powerful
4 types of muscles
- prime mover
- antagonist
- synergist
- fixator
muscle with the major responsibility for a certain movement
prime mover
muscle that opposes or reverses a prime mover
antagonist
muscle that aids a prime mover in a movement and helps prevent rotation
synergist
stabilizes the origin of a prime mover
Fixator
nomenclature
origin and insertion of muscle + shape of muscle + action of the muscle
7 major descriptive categories of naming skeletal muscles
- direction of fibers
- location
- size
- number of origins
- shape
- origin and insertion
- action
Autoimmune disease that causes chronic, progressive damage to the NMJ (neuromuscular junction)
Myasthenia gravis
In this clinical disorder, immune system inappropriately produces antibodies that bind and block some ACh receptors
Myasthenia gravis
- Weakness of eye muscle (Double vision)
- Difficulty in swallowing, later chewing and talking
- Muscle of the limbs may be involved
Myasthenia Gravis
- Inherited muscle destroying disease that causes progressive degeneration of skeletal muscle fibers.
- DUCHENNE MUSCUKAR DYSTROPHY
Muscular dystrophy
- X Chromosomes: boys : ages 2 and 5
- Falls often, difficulty running, jumping
- 12 y/o unable to walk
- Respiratory and cardiac failure: 20 and 30 y/o
Muscular dystrophy
- Painful, non articular, rheumatic disorder
- 25 to 50 y/o
- 15 x more common in women
Fibromyalgia
- Affects fibrous connective tissue components of muscle, tendons and ligaments
- Pain that results from gentle pressure at specific areas “tender points”.
- Even without pressure, pain, tenderness and stiffness of muscles, tendons and surrounding soft tissues.
Fibromyalgia
This is s due to increased production of myofibrils, mitochondria, sarcoplasmic reticulum, and other organelles. It results from very forceful, repetitive muscular activity, such as strength training.
Muscular hypertrophy
This is a decrease in size of individual muscle fibers as a result of progressive loss of myofibrils. Atrophy that occurs because muscles are not used is termed disuse atrophy
Muscular atrophy
Refers to sudden involuntary contradiction of a single muscle in a large group of muscle
Spasm
Painful spasmodic contraction
Cramp
Spasmodic twitching, involuntary
Tic
Rhythmic, involuntary purposeless contraction that produces a quivering or shaking movements
Tremor
Involuntary brief twitch of an entire motor unit that is visible under the skin
Fasciculations
Spontaneous contraction of a single muscle fiber that is not visible under the skin
* destructions of motor neurons
Fibrillation
