Chapter 10: Muscle tissue & organization SYDNEY Flashcards
What are the properties of muscle tissue?
- Excitability
- Conductivity
- Contractility (tension & shorten)
- Elasticity
- Extensibility
What are the different functions of skeletal muscle?
- Movement
- Posture
- Temperature regulation
- Storage/ movement (sphinters)
- Support
Fascicles
Bundles of muscle fibers
what is endomysium?
within muscle; innermost connective tissue layer; fiber
what is perimysium?
surrounds the fascicles; contains extensive arrays of blood vessels & nerves that branch to supply each individual fascicle
what is epimysium?
a layer of dense irregular connective tissue that surrounds the whole skeletal muscle
what is deep fascia?
additional expansive sheet of dense irregular connective tissue that lies external to the epimysium
- separate individual muscles
-binds together muscles w/ similar functions
-forms sheaths to help distribute nerves, blood vessels & fills spaces b/t muscles
which layer is deep fascia internal to?
superficial fascia
what is superficial fascia?
composed of areolar and adipose distinctive tissue that separates muscle from skin
what level is epimysium?
a muscle
what connective tissue covering goes with fascicle?
perimysium
what connective tissue covering goes with muscle?
endomysium
what connective tissue covering goes with fascicle?
Perimysium
what connective tissue covering goes with Fiber?
Endomysium
Muscle fiber
- Located in sarcolemma
- Sarcoplasm
- Contains myofibrils (length of cells & myofilaments)
Myosin
Thick filaments (11nm)
Actin
-Thin filaments (9nm)
- Also tropomyosin & troponin (regulates contraction)
- Nebulin (thin filament formation)
In context of myofilaments, size & density difference between _____________ filaments
thick & thin
Light microscope with myofilaments
-A- bands (appear dark) (thick filaments)
- I bands (appear light) (thin filaments)
Electron microscope related to myofilaments
- H-zone (thick filaments only)
- M-line (attachment site for thick fibers)
- Z-disc (attachment site for thin fibers)
Sarcomere
- The distance between two Z- disc
- The functional unit of skeletal muscle contraction
Neuromuscular junction
- Contains the synaptic knob (synaptic vesicles (contains acetylcholine (ACH))
- Contains synaptic cleft (acetylcholinesterase (breaks down ACH)
- Motor end plate (located in sacrolemma, folded, & has ACH receptors)
Sliding filament theory
-Thick & thin fibers pass each other during contraction
- H-zone & I-band disappear at maximal contraction
- Overall shortening
-Tension
What are the steps involved in skeletal muscle contraction?
- Nerve impulse arrives at the neuromuscular junction
- ACH released into synaptic cleft
- Ach binds to receptors in the motor end plate initiating an impulse along the sarcolemma
- Impulse travels along sacrolemma & T-tubules
- Calcium is released from the sarcoplasmic reticulum
6.Calcium ions bind to troponin
- Troponin moves tropomyosin & exposes active sites on the actin
- Myosin heads bind to active sites & pivots
- ATP binds to myosin head
- Myosin head detaches from actin & resets
11.Nerve impulse stops
- Calcium ions transported back to sarcoplasmic reticulum
- Tropomyosin covers active sites, myosin can’t bind muscles relaxes
Motor units
- “All or none” principle
- Muscle tone
(- resting tension in skeletal muscles - not enough forces for movement
-some motor units always active)
Isometric contraction
Length of muscle doesn’t change (tension greater than or equal to resistance)
Isotonic contraction
Fibers shorten
(- Tension is greater than resistance)
What are the two types of isotonic contractions?
- Concentric contractions
- Eccentric contractions
Concentric contractions
Actively shortens a muscle
Eccentric contractions
Controlled lengthening of a muscle
Slow oxidative fibers
- Relatively thinner
- Slower/ less powerful contractions
- Stay contracted longer
-Aerobic respiration - Dark red (myoglobin)
- Heavily vascularized
-Many mitochondria
Fast Oxidative fibers
-Intermediate fibers
-Fast/powerful contraction
-Aerobic respiration
- Lighter red (less myoglobin)
- Not as vascularized
- Fewer mitochondria
- Medium endurance
What are the different arrangements muscle come in?
-Circular
-Parallel
-Convergent
-Pennate (unipennate, bipennate)