Muscular System Flashcards
Functions
- Movement of Body 2. Maintenance of Posture 3. Respiration 4. Production of Body Heat 5. Communication 6. Constriction of organs and vessels 7. Contraction of the Heart
Contractility
Ability of muscle to shorten forcefully
Excitability
Capacity of muscle to respond to stimulus
Extensibility
Muscle can stretch beyond its normal resting length and still be able to contract
Elasticity
Ability of muscle to recoil to its original resting length after its been stretched
Skeletal Muscle
-responsible for locomotion, facial expressions, posture, respiratory functions, etc -has striations -voluntary and involuntary (RELFEXES)
Smooth Muscle
-Found in the walls of hollow organs and tubes, blood vessels, eyes, glands, and skin -no striations -involuntary
Cardiac Muscle
-heart -has striations -involuntary- automatic nervous and endocrine systems
Skeletal muscle fibers
muscle cell
Fasciculi
bundles of muscle
Perimyseum
heavy connective tissue layer surrounding fasciculi
Epimysium
layer of connective tissue surrounding the entire muscle- composed of dense collagenous connective tissue
Fascia
connective tissue sheets within the body
Muscular fascia
separates and compartmentalizes individual muscles or groups of muscles
Motor neurons
specialized nerve cells that stimulate muscles to contract
Muscle Structure
Striations
Alternating light and dark bands give a striped appearance
Myoblasts
less mature, multinucleated cells that develope into muscle fibers
Hypertrophy
Enlargment of muscles due to an increase in SIZE of muscle fibers
Sarcolemma
plasma membrane of a muscle fiber
External Lamina
deeper, thin layer of delicate connective tissue layer located on outside of sarcolemma
- consists of reticular (collagen) fibers
Endomysium
the other layer of the sarcolemma- much thicker
Transverse Tubules (T Tubules)
tubelike invaginations of the sarcolemma
extend inward, connecting extracellular environment with interior of the muscle fibers
Sarcoplasmic Reticulum
highly organized smooth endoplasmic reticulum
Sarcoplasm
cytoplasm- cell packed with organelles including mitochondria and energy storing glycogen granules
Myofibrils
bundles of protein filaments in the sarcoplasm
Myofilaments
protein filaments in the myofibril
Actin- thin
Myosin- thick
Sarcomeres
actin and myosin myofiliments for highly ordered units
joined end to end to form myofibrils
Parts of a muscle
Z Disk
filamentous network of protein forming a dislike structure for the attachment of actin myofilaments
Isotropic Band (I Band)
includes a Z Disk- extends from each side of z disk to ends of myosin filaments
Anisotropic Band (A Band)
extends the length of the myosin myofilaments within a sacromere
H zone
- in the center of each A band- actin and myosin myofilaments dont overlap
- only myosin myofilaments are present
M line
middle of H zone- delicate filaments attach to the center of myosin myofilaments
Titin
largest know protein- holds actin and myosin in place– muscles ability to stretch and recoil
Sliding Filament Model
shortening of sarcomeres that is responsible for contraction of skeletal muscles
Action Potentials
electrical signals that travel from the brain or spinal cord along the axons to muscle fibers and causes them to contract
Ion channels- 2 major types
nongated (leak) and gated
Ligan-gated ion channels
open when a ligand (neurotransmitter), a chemical signal, binds to a receptor that is part of the ion channel
Polarized
the inside of most plasma membranes is negatively charged compared with the outside
Resting membrane potential
the charge difference across the plasma membrane of an unstimulated cell
Action Potential- resting membrane potential
charge difference across the plasma membrane of cells
