Test #3 Flashcards
All muscles produce
Heat during contraction
Cells of muscles (skeletal)
Sarcolemma - muscle fiber plasma membrane
Sarcoplasm - muscle fiber cytoplasm
Glycosomes - glycogen storage
Myoglobin - O2 storage
Organelles
–Myofibrils - contractile unit; densely patched rodlike elements; contains striations, sarcomeres, 1000’s of myofilaments; account for 80% of muscle cell volume
–Sarcomere - unit of myofibril; z-disc to z-disc
–Sarcoplasmic reticulum - stores and releases Ca+
–T tubules - protrusion of sarcolemma into cell to reach each muscle fiber
Cells of muscles (smooth)
Uninucleated, no striations, no sacromeres, no protective sheaths (endomysium only)
Varicosities of nerve fibers instead of neuromascular junctions
Diffuse junction - wide synaptic cleft
No troponin; calmodulin binds Ca2+
Tropomyosin serves same function as in skeletal,
Caveola - sarcolemma of smooth muscle contains pouch-like infoldings
Myosin heads across the whole length (as opposed to skeletal which is only at the ends)
Where are ACh receptors found?
Junctional folds of the sarcolemma/motor end plate
Steps from nerve stimulation to muscle contraction (skeletal; steps/summary)
— A. Neuromuscular junction
— B. Muscle fiber excitation
— C. Excitation-Contracting coupling (activities of the triad)
— D. Cross bridge cycling occurs via the sliding of myofilaments
Summary of steps from nerve stimulation to muscle contraction
1) Motor neuron AP
2) N/T release
3) Muscle cell AP
4) Release of Ca2+ from SR
5) ATP-driven power stroke
6) Sliding of myofilaments
What is an axon terminal?
The bulbous distal endings of the terminal branches of an axon where neurotransmitters are released. Takes in Ca2+, releases ACh
What causes action potential?
Depolarization of the sarcolemma - the rising membrane voltage crosses a threshold value, and an AP is generated
Three parts of the motor neural junction
- Axon terminal
- Synaptic cleft
- Muscle/motor end plate
Troponin vs calmodulin
Troponin - skeletal muscle; Ca2+ binds to troponin which causes tropomyosin to expose myosin-binding sites
Calmodulin - smooth muscle; Ca2+ binds to Calmodulin which activates it (which activates MLCK enzymes, which then phosphorylyse heads of the myosin)
MLCK
Enzyme (myosin light chain kinase) this activates myosin heads in smooth muscle; causes activation of ATPase
MLCP
Enzyme (myosin light chain phosphates) that dephosphorolyses myosin heads in smooth muscle; causes deactivation of ATPase
ATPase
Enzyme that hydrolyzes ATP, providing the energy for the power stroke
Three ways to create ATP in the muscles
1) Direct phosphorylation of ADP by creatine phosphate (CP)
–Creatine phosphate in the muscle cell stores energy that will be transferred to ADP to recreate ATP
–No oxygen use, 1 ATP per CP, 15 seconds energy
2) Anaerobic pathway: glycolysis and lactic acid formation
–No oxygen use, 2 ATP per glucose & 2 pyruvic acid, 30-40 seconds energy
3) Aerobic pathway - glucose plus three acids AND OXYGEN aerobically respirate in mitochondria
–OXYGEN USE, 32 ATP per glucose, hours of energy
EPOC
Excess post-exercise oxygen consumption; EPOC is the amount of oxygen our body consumes following an exercise session that is above and beyond the pre-exercise oxygen consumption baseline
Structural and functional characteristics of the three types of muscle fibers
Muscle twitch phases
Latent - events of excitation-contraction coupling - no muscle tension
Contraction - cross-bridge formation - tension increases
Relaxation - Ca+ reentry into sarcoplasmic reticulum - tension decreases to zero
Treppe
Warming up; enhances availability of Ca and efficiency of enzymes
Hypertrophy vs hyperplasia
Hypertrophy - increase in size; hyperplasia - increase in number
Latch-bridge
A cross-bridge connection that happens in smooth muscle where the connection can hold indefinitely without ATP resulting in a low energy contraction
Isometric contraction vs isotonic contraction
Isometric contraction - no muscle length change; muscle tension increases but does not exceed load; e.g., pushing against a wall
Isotonic contraction - muscle length changes because muscle tension exceeds load
A) Eccentric contractions - muscle lengthens
B) Concentric contractions - muscle shortens
Triad
Triad is a T tubule & two terminal cisterns (sarcoplasmic reticulum - releases and reabsorbs calcium)
Motor end plate
Junctional folds of the sarcolemma
Disuse atrophy
Degeneration and loss of mass due to immobilization or loss of neural stimulation - can begin almost immediately
Agonist/antagonist/synergist
Prime mover (agonist) - produces specific movement
Antagonist - opposes or reverses particular movement
Synergist - helps prime movers (adds extra force or efficiency)
Fixator - type of synergist that stabilized the origin of another muscle
First class lever
Resistance - fulcrum - force
Scissors
Atlanto-occipital joint of the neck tips neck back instead of falling forward
Second class lever
Fulcrum - resistance - effort
Wheel barrow
Standing on toes
Third class lever
Resistance - effort - fulcrum
Forceps
Elbow joint during bicep curl
Steps from nerve stimulation to muscle contraction (skeletal; part 1)
— A. Neuromuscular junction
1) Action potential (AP) arrives at axon terminal
2) Voltage gated calcium channels open, calcium enters motor neurons
3) Calcium entry causes ACh neurotransmitter to be released into synaptic cleft
4) ACh binds to ACh receptors on sarcolemma
5) ACh opens gates of cell, cell brings in Na+ which changes it to positive, resulting in local end plate depolarization called end plate potential (EPP)
6) Acetylcholenesterase - destroys ACh
Steps from nerve stimulation to muscle contraction (skeletal; part 2)
— B. Muscle fiber excitation
1) The EPP triggers AP in the adjacent sarcolemma
Steps from nerve stimulation to muscle contraction (skeletal; part 3)
— C. Excitation-Contracting coupling (activities at the triad)
1) Excitation: AP in sarcolemma travels down T-Tubules
2) Contraction: AP effect on terminal cisterns/sarcoplasmic reticulum releases Ca2+ into cytoplasm
3) Ca2+ binds to troponin which shifts tropomyosin to uncover the actin
4) Myosin heads create cross-bridges leading to ATP-driven power stroke
Steps from nerve stimulation to muscle contraction (skeletal; part 4)
— D. Cross bridge cycling occurs via the sliding of myofilaments
Structural organization of the skeletal muscle (sheaths)
Connective tissue sheaths
–Deep fascia - dense irregular CT that surrounds muscles and bind similar muscles
–Epimysium - surrounds a muscle
–Perimysium - surrounds fascicle (bundle of fibers)
–Endomysium - surrounds individual muscle fiber
–Muscle fiber - contains microfibrils
–Microfibril - contains 100s to 1000s of myofilaments
–Myofilaments - contain bundles of actin and myosin
Primary/secondary curvature
Primary curvature (at birth) - thoracic and sacral convex
Secondary curvature (after birth) - cervical and lumbar concave
Abnormal spine curvatures
Scoliosis - s-shape
Kyphosis -hunchback
Lordosis - pregnant
Vertebral regions and their characteristics
Cervical (7)
–Atlas (C1) - loses body to axis during development
–Axis (C2)
—–Only ones that have a hole in transverse process for blood flow to brain
Thoracic (12)
–Only ones to have costal facets for ribs
Lumbar (5) - big to carry weight
Sacrum (5) fused
—Coccyx 3-5 fused
Insertions vs origins
In axial, origins are medial, insertions are lateral
In appendicular origins are proximal, insertions are distal
ONLY INSERTIONS EVER MOVE
Muscle disorders
Myasthenia gravis - destruction of ACh receptors; drooping eyelids
Rigor mortis - due to no ATP to release actin and myosin molecules
Bone disorders
Osteomalacia (adults) & rickets (children) - vit. D deficiency
Osteoporosis - bone absorption exceeds deposit
Paget’s disease - excessing and haphazard bone deposit & resorption causes fast growth & poor developmen
Joint disorders
Osteoarthritis - cartilage broken down faster than replaced (local)
Rheumatoid arthritis - chronic inflammatory autoimmune disease (systemic)
Gouty arthritis - deposition of uric acid crystals
Lyme disease - caused by bacteria transmitted by tick bites
Classes of bones with examples
Long bone - medullary cavity, limbs
–Epiphysis
—–Ends of long bones; compact surrounding spongy
-Epiphysial plate
-Diaphysis - shaft
—–Compact bone surrounding central medullary cavity which contains yellow marrow in adults
Short bone - cube shaped bones in wrist & ankle (patella is sesamoid)
Flat bones - sternum, scapulae, ribs, most skull bones; Wormian bones (sutural) develop within sutures of the skull
Irregular bones - complicated shapes, hip & vertebrae
Structure of short, irregular, and flat bone
—Diploe covered by compact bone
—Compact bone sandwiched between CT membranes
—Bone marrow scattered through spongy (NO DEFINED MARROW CAVITY)
Axial vs appendicular skeleton
Axial (vertebral columns, ribs, clavicle, cranium)
1:2 ratio (number of bones in arms vs legs)
Compact vs spongy bone
Compact bone (lamellar)
–Haversian system, consisting of rings of bone matrix called lamellae
–Central Haversian canal (contain NAV) & Volkman’s/perforating canals (right angle; connect NAV of periosteum, medullary cavity and central canal)
–Collagen runs in different directions to create strength;
–Support weight and withstand tension stress
Spongy bone (trabeculae)
–No Haversian system, contains irregularly arranged lamellae
–Stores bone marrow
–Site of hematopoiesis
–Add strength and flexibility to bone
Diploe
Diploe is a subcategory of trabeculae of flat, cranial bone; spongy bone sandwiched between two layers of compact bone
Parts and sections of long bone
Epiphysis
Ends of long bones; compact surrounding spongy
Epiphysial plate
Diaphysis - shaft
Compact bone surrounding central medullary cavity which contains yellow marrow in adults
Locations of red marrow
Children: spongy bone and medullary cavities of long bones
Adults: portions of axial skeleton and in proximal epiphyses of humerus and femur, ossa coxae
What gives bone flexibility/strength?
Trabeculae
Organic/inorganic
Organic- responsible for flexibility & resilience due to sacrificial bonds in or between collagen
–Cells, matrix (ground substance, protein fiber)
–Osteogenic cells, osteoblasts, osteocytes, bone-lining cells, osteoclasts
Inorganic - responsible for hardness and resistibility to compression
–hydroxyapatites (mineral salts), mainly calcium phosphate crystals
General functions of the skeletal system
1) provides support and protection
2) sites for muscle attachment
3) site of hemopoiesis (blood cell production)
4) stores calcium & phosphorus
Appositional vs interstitial growth
Appositional - occurs in perichondral surface (causes width growth)
Interstitial growth - occurs at epiphysial plate (hyaline cartilage) (causes length growth)
Which hormones stimulate osteoclasts and Ca ions? Which stimulate osteoblasts?
Osteoblasts - growth hormone, thyroid, testosterone/estrogen
Osteoclasts - Parathyroid (raises Ca+), leptin & serotonin inhibit oseoblast
Fracture classifications
Greenstick fracture - children
Spiral fracture - contact sports
Chronological order of bone repaair
1) A hematoma forms
2) Fibrocartilaginous callus forms
3) Bony callus forms
4) Bone remodeling occurs
Endochondral ossification vs intramembranous ossification locations
Endochondral ossification - basically all bones inferior to base of skull, except clavicle
Intramembranous ossification - forms skull and clavicles
What affects the velocity & duration of muscle contraction?
The load on the muscle fibers
Load on the muscle fibers affects what?
Velocity & duration of muscle contraction
Cells of bone tissue
Osteogenic - stem cell in periosteum and endosteum (become osteoblasts or bone-lining cells when stimulated)
Osteoblast - secretes bone matrix, responsible for growth
Osteocytes - no longer dividing, maintains bone matrix
Bone-lining - maintain matrix
Osteoclasts - bone resorption cell; derived from the same hematopoeic that become microphages
Similarities and differences between all muscles (ESSAY QUESTION)
Similarities
1) Excitability - ability to receive and respond to stimuli
2) Contractility - ability to shorten forcefully when stimulated
3) Extensibility - ability to be stretched
4) Elasticity - ability to recoil at resting length
Differences
1) Smooth muscle has less elaborate SR and no T tubules; SR does store intracellular Ca2+ but most calcium used for contraction has extracellular origins
2) Sarcolemma of smooth muscle contains pouch-like infoldings called caveolae which contain Ca2+ channels
3) Smooth muscles are electrically connected via gap junctions (skeletal muscles are electrically isolated)
4) No striations or sarcomeres in smooth, but do contain myosin and actin filaments
5) Myosin in smooth muscle has heads along the entire filament
Sarcomere & striations
Sarcomere - unit of myofibril; z-disc to z-disc
Myofilaments - orderly arrangement of actin and myosin
–Actin - thin, light; tropomyosin & troponin are regulatory protein bands; binds with calcium which cause tropomyosin to disengage from site and myosin head’s interact to create cross-bridges
–Myosin - thick, dark; globular heads, myosin tails; during contraction the heads bind to receptors in thin filaments forming cross-bridges
1) I band (“I, acting alone”) - thin filament only
2) A band - length of thick filament (happens across thick and thin filament)
3) H zone - thick filament only
4) Z disk - connectin to actin
5) M line - thick filament linked together with band
Functional descriptions of joints & their locations
Synarthrosis - immobile
–Suture
Amphiarthrosis - slightly mobile
—Pubic symphysis
Diarthrosis - freely mobile
-Uniaxial
—i) Plane - intercarpal
—ii) Hinge - elbow
—iii) Pivote - atlantoaxial
-Biaxial
—iv) Condylar - metacarpal
—v) Saddle - first metacarpal
-Multiaxial
—vi) Ball and socket - hip
Types of cartilages and locations
Hyaline (most abundant) - support, flexibility and resilience, type II collagen
–joints
–ribs
Elastic - similar to hyaline but w/elastic fibers
–external ear
Fibrocartilage - thick collagen fibers - combines considerable tensile strength and ability to resist compressive forces & distribute them evenly to bone
–intervertebral disc
–pubic symphysis
–knee menisci
Compare & contrast bones/cartilage
Bones
1) Support
2) Protection
3) Movement
4) Mineral and growth factor storage
5) Blood cell formation
6) Triglyceride (fat) storage
7) Hormone production
Cartilage - no blood vessels or nerves
1) Support
2) Flexibility
3) Resilience
Bone formation (osteogenesis) vs bone remodeling/repair
Ossification (osteogenesis) - begins in month two of development; post-natal until early adulthood
–Endochondral ossification - bones form by replacing hyaline cartilage;
–Intramembranous ossification - bone develops from fibrous membrane
–Interstitial - pushes epiphysial plate up and away from diaphysis
–Appositional - width (most typical in bone remodeling/repair)
Remodeling/repair is lifelong
