Muscles Flashcards
General functions of muscle tissue?
- excitability
- extensibility
- elasticity
- conductivity
- contractility
Functions of muscle system?
- movement
- stability
- posture
- control of openings/passages
- heat production
Agonist (prime mover)
Produces the most force during joint action
Synergist
- aids the prime mover (PM)
* may stabilize a joint
Antagonist
- Apposes the prime mover
* maintains some tension on joint to limit force of PM
Origin
Bony site of attachment that is stationery
Insertion
Attachment site that is more mobile
Action
The AFFECT produced by a muscle
Intrinsic
The origin and the insertion are in the same place
Extrinsic
Acts upon a designated region, but has its origin somewhere else
Kissing muscles?
Orbicularis oris
Longest muscle in body?
Sartorius
Which muscle plantar flexes foot?
How attached to heel?
Soleus-O:fibula/tibia. I:calcaneous
Gastrocnemius-O:condyles, popliteal surface. I:calcaneous
Direct muscle attachment?
- appears to be little muscle separation
* collagen fibers between gap of muscle and bone
Indirect muscle attachment
- muscle ends short of its bony destination
* bridged by a tendon
Muscle
- EPIMYSIUM
- Contractile organ
- composed of fascicles
- nerves/blood vessels
Fascicles
- PERIMYSIUM
* bundles of muscle fibers
Muscle Cell/tissue
- ENDOMYSIUM
- enclosed in sarcolemma
- myofibrils
- multiple nuclei
Myofibrils
- Z-discs
- t-tubules
- myofilaments (thin and thick)
- surrounded by sarcoplasmic reticulum
Sarcomere
- thick and thin filaments
* contractile unit
Myofilaments
- contraction process
* myosin & actin•(slide over each other to shorten sarcomere)
EPIMYSIUM
Surrounds entire muscle
Fibrous sheet
PERIMYSIUM
Wraps muscle fibers into bundles of fascicles
Connective tissue
ENDOMYSIUM
Surround EACH muscle fiber
Connective sheath
Sarcolemma
Surrounds the muscle fiber (specialized plasma membrane)
T-Tubules
Signals SR to release CA++
Sarcoplasm
Cytoplasm of cell
Sarcoplasmic reticulum
Surrounds each myofibrils
Reservoir Ca++ ions
Myofibrils Functions
- T-tubules: signal SR. To release Ca++
- : releases Ca++
- Z-disc: a segment of myofibril
- myofilaments: myosin & actin
Regulatory Proteins
Tropomyosin
Troponin
Ca++ ions released from SR and bind to troponin, releasing tropomyosin
Contractile proteins
Myosin
Actin
Myosin attaches to the actin active site after the tropomyosin has been released
Rigor Mortus
- 3-4 hrs after death
- Stiffening/hardening muscles
- No ATP available to release cross-bridges
Isometric INC
No change in length
Change in tension
Isotonic ICN
Change in length
No change in tension
Concentric
Muscle shortens as it maintains tension
Eccentric
Muscle lengthens as it maintains tension
Smooth muscle
- does not move skeleton
- walls of blood vessels, digestive tract, airways
- involuntary movement
Skeletal muscle
- voluntary
- attached by tendons to skeleton
- attaching bone to bone
Recruitment of motor units?
Activation of additional motor units to accomplish an increase in Contractile strength in a muscle
Motor Unit=one motor neuron+muscle fibers
Muscle Fiber
- A single muscle cell enclosed in sarcolemma and is multinucleated
- contains bundles of myofibrils
