Skeletal Muscle Flashcards
Primary Functions of the Skeletal Muscle (5)
- Movement
- Support
- Posture
- Temperature regulation
- Communication
Skeletal muscles create _____ by ____and ___ on tendons, which are connected to the ____.
Movement
movement
contracting
pulling bones
Muscles in the ___ wall support ___ organs and shield ___ from injury.
Support
abdominal
visceral
tissues
Muscles also continuously contract to hold the body still and maintain an upright sitting or standing _____.
Posture
Skeletal muscle is about ___ % of __ ___, which gives it a ______ effect on body ___.
*Temperature regulation* 40 body mass disproportionate temperature
Facilitates all modes of _____ communication, including ____, ____, ____, ___ ___ and ____.
interpersonal speaking typing writing facial expression gestures.
Red stands for ?
muscle tissue
White stands for?
tendons
Muscle is actually composed of not only ___ ___, also __ ___, ___ __ and ___.
skeletal muscles
connective tissue
blood vessels
nerves
Skeletal muscles are _____ material; this means that __ ___ are organized wishing cells.
hierarchical
molecular motors
Muscles only ?
PULL
human body has more than ___ skeletal muscles
650
Each muscle is wrapped in a connective tissue layer ___
epimysium
Epimysium wraps together a bundle of ____ ___?
Muscle Fibers
Each bundle is called a?
fascicle
what surrounds the fascicle?
endomysium
A fibrous connective tissue sheath that surrounds the entire muscle.
Epimysium
A connective tissue sheath surrounding each muscle fiber and contains capillaries and nerves
Endomysium
A connective tissue sheathe surrounding several muscle fibers.
perimysium
A tough band of fibrous connective tissue that connects muscle to bone.
Tendons
A membrane that covers the outer surface of all bones.
Periosteum
provide anchorage and support to nerves and blood vessels that innervate and supply energy to the muscle fibers
epimysium and perimysium
Main Features of A skeletal Muscle Fiber: (5)
- Contents
- Development
- Size and shape
- Orientation
- Satellite cells
Specialized structures
Ex. sarcoplasm
and Sarcoplasmic reticulum
Contents
when myoblasts fuse to form myocytes
Development
Myogenesis
Cylindrical cells, diameter of 10-100 um very long up to 23 inches
Size and Shape
Mostly oblique to the muscles axis of force
orientation
Regenerative myoblasts that did not fuse during development
satellite cells
bundles of contractile proteins
myofibrils
2 types of myofilaments
- Actin
2. Myosin
thin filament looks like pearls on a string
actin
thick filaments, looks like double headed golf clubs
Myosin
Actin comes into dif. Forms:
F- actin
G- actin
initiates many cellular processes including cell motility and muscle contractions
is a twisted strand of ___.
F- actin
G- actin
Monomer from which F- actin is produced.
G-actin
The myosin heads, bind to actin to form a ____
cross bridge
Actin and myosin are arranged longitudinally in repeating units along the myofibril
sarcomeres
smallest contractile units of skeletal muscles
repeating units of longitudinally arranged actin and myosin
allow for the sliding filament model of muscle contraction
boundaries formed by z lines
sacromere
- Muscle unit in the ___ sends ___.
- ____ travels through the ___ ___ to ___ ___.
- Motor action potential stimulated and ____ slides
brain impulse impulse spinal cord motor neuron sarcomeres
it is where the axon terminal of the alpha motor neuron and the membrane of the muscle fiber meet
Neuromuscular junction
Alpha motor neurons release a specific neurotransmitter known as
acetylcholine (ACh)
is an autoimmune disorder and common neuromuscular disease.
results from antibodies that block or damage nicotinic acetylcholine receptors at the NMJ
myasthenia gravis
a single contraction and relaxation cycle within a muscle fiber
muscle twitch
Action potential depolarizes the sarcolemma
sarcoplasmic reticulum releases Ca 2+
no tension produced yet.
Latent Phase
Muscle fiber peaks
cross bridges interactions are occurring as actin binding sites are exposed
Contraction phase
Cat 2+ levels decrease
Binding sites on actin become covered
Number of cross bridges decline
relaxation phrase
addition of one twitch
wave summation
is a sustained muscle contraction caused by a motor neuron firing action potentials at a very high rate
tetanic contraction
Tetanic Contraction can be (2)
Fused
Unfused
muscles partially relax in between
low rate of stimulation
unfused
muscles do not relax
high rate of stimulation
fused
which is the ability of a muscle to maintain a continuous and passive partial contraction.
important for posture, balance and preventing injury
Muscle tone
Factors affecting Muscle tone: (2)
structure of the muscle including its connective tissue and size of the elastin component
active muscle tone
describes the link between resting muscle length and tension generation
Length- Tension Relationship
The sequence of events that converts action potentials in a muscle fiber to a contraction
excitation-contraction coupling
More ATP is produced than needed
AtP transfers the energy to creatine
Resting Muscle
Generates ATP from creatine phosphate
ATP is continuously generated at the same rate is used
Contracting Muscle
Energy source for direct phosphorylation
CP
Energy source for anaerobic
Glucose
Energy source for aerobic
glucose, pyretic acid
free fatty acids
amino acids
RECOVERY (3)
Latin acid removal
High Intensity exercise
Muscle soreness
lactic acid can be recycled back to pyretic acid
used by mitochondria to generate ATP or rebuild glycogen reserves
Also shutter through blood to liver and back to muscle (cori cycle)
Lactic acid removal
maintains/ improves muscular strength, endurance, mass, fiber size, metabolic capacity, power, resting metabolic rate, bone mineral density and overall physical function
High Intensity exercise
usually lasts 3-4 days and is most intense after eccentric contractions
May be caused by very small muscle tears or injury to connective tissues/tendons
Principle of overload: body adapts after rest and becomes stronger
Muscle Soreness
Features of Muscle aging
- Muscle fibers get thinner
- Muscular strength declines
- Muscles get less flexible
- Tolerance for exercise decreases
- Ability to recover from injuries decrease.
Sarcopenia: age-related loss of both muscle fiber size and number of muscle fibers
Muscle fibers get thinner
Muscles contain less ATP, CP and glycogen reserves
Have less strength and endurance, and fatigue more easily
Muscular strength declines
Fibrosis: age-related development of fibrous tissue, restricting movement and circulation
Muscles get less flexible
Related to decrease in ability to thermoregulate, and increase in tendency to fatigue
Tolerance for exercise decreases
Increase in fibrous tissue prevents injured tissue from healing optimally
Ability to recover from injuries decreases
