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48 Cards in this Set

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Function of Skeletal Sys in general and 2 Division of Mammalian Skeleton
Primarily=physical support
[Axial] Skeleton: Protects delicate vital organs; comprised of skull, vertebral column, rib cage
[Appendicular]: meant to provide lever upon which skeletal muscles act
OTHER purp: skel bone houses marrow-->blood-forming house
Major components of skeleton
are 2
Tissue Type and Characteristics of Cartilage
Connective tissue; flexible, soft; nerveless; avascular (receives nourishment from capillaries in nearby connective tissue and bone
Cartilage is composed of....which is composed by....
Chondrin: a firm but elastic matrix.
Cartilage is the principal component of __skeletons
embryonic (in higher animals)... in mammals most cart hardens and calcifies to bone
Locations of cartilage in humans
external ear, nose, walls of larynx, trachea, skeletal joints
5 listed
Tissue Type and Characteristics of Bone
Mineralized connetive tissue w/ ability to withstand connective stress; bone tissue is hard and strong while being somewhat elastic and lightweight

2 basic types of bone and detailed descriptions
[COMPACT] bone: dense bone that to the naked eye has no cavities
[CANCELLOUS/spongy] bone: nuch less dense w/ interconnecting lattice of bony spicules (tribeculae). cavities of lattice (b/t spicules) contain red and/or yellow marrow.
yellow vs red marrow?
yellow is inactive and filled with adipose tissue
red is involved in blood cell formation
Overall bone structure of appendages
think dog bone
DIAPHYSIS: long shaft, mostly made of compact bone with a core of marrow, which connects...
EPIPHYSES: dilated ends of bone, composed of spongy bone surrounded by thin layer of compact.
EPIPHYSEAL PLATE: disk of _cartilagnous_ cells that sep diaphy from epiphy, and site of longitudinal growth
PERIOSTEUM: surrounds long bone, site of muscle tissue attachment
4 parts, only one has spongy
Compact Bone Composition
dense, hardened bone matrix w/ organic and inorganic componenets.
ORGANIC: includes protein (mostly collagen fibers and glycoproteins)
INORGANIC: CA, P (phosphate), OH- (combine to form _hydroxyapatite_ crystals) and Na, K, MG ions
What gives bones their characteristic strength?
hydroxyaptite crystals combine with collagen fibers
Osteo____ build bone
Osteo____ destroy bone
Blasts builds

Clasts destroy!
Structural unit of bone?
Osteon OR Haversian system
Describe the layout of an osteon
consists of a central microscopic channel called a __Haversian canal__, surrounded by many concentric circled of bony matrix called lamellae
Haversian canals contain...
blood vessels, nerve fibers, and lymph vascularizing and innervating bone tissue
The lamellae matrix houses....
Mature bone cells, Osteocytes, within the _lacuna_ (spces in the matrix); Canaliculi interconnect each other&lacunae&Haersian canal, exhcanging nutrients and wastes
2 Methods of Ossification
(aka Bone Formation) occurs in two ways: endochondral ossification or intramembrance ossification
Endochondral Ossification
cartilage is replaced by bone; how most long bone form
Intramembrance Ossification
Mesenchymal (embyrionic, undifferentiated) is transformed into and replaced by bone
Talk about bone remodeling
continuous process. bone reformation: inorganic ions Ca and P are absorbed from the blood for use in bone formation. Bone resorption: tohse same ions are released into the blood
Regulation of Bone Remodeling?
By PTH (parathyroid hormone) and calcitonin.
also bone use and stress. PTH raises blood calcium levels by stimulation Ca2+ release from bones and decreasing kidney Ca2+ in kidneys. PTH also converts vitamin D to its active form, which stimulates intestinal calcium absorption.
Movable joint consists of....
a _synovial_ capsule, which has an articular (joint) cavity. Movement of the joint is facilitated by the synovial fluid which lubricates the joint; and also by the articular cartilage on the apposing bone surface which is smooth
Skeletal Muscle
Voluntary Movement; controlled by the Somatic nervous system
Skeletal Muscle:
Makeup of Muscle
Long parallel fibers--> muscle fibers.
Skeletal Muscle:
Muscle Fibers?
Multinucleated cell created by the fusuion of many mononucleate enbryionic cells. Nuclei are usally on the periphery of the cell. Embedded w/in the fibers are _MYOFIBRIL_ filaments.
cytoplasm of muscle fibers: sarcoplasm.
Cell membrane: sarcolemma
Skeletal Muscle:
Unit of Myofibrils
sarcomeres... divided by transverse tubules
Skeletal Muscle:
Covering of Myofibrils
Sarcolemma, can propagate an action potential
Skeletal Muscle:
T system
transverse tubules that are oriented perpendicularly to myofibrils. T sys provides channels for ion flow throughout muscle fibers & can also prop an axn potential
Skeletal Muscle:
Looks like?
striated.. has light and dark bands. Also typified as red or white.
Skeletal Muscle:
Red vs white
Red Fibers: slow-twitsh, high myoglobin content (protein that resembles hemoglobin) and many mitochondria--> long dist runners, aerobic activity
White fibers: fast-twitch, abaerobic--> less myoglobin and fewer mitochondria, greater rate of contraction but more
Smallest 'thread'
The _Myofibril_ filaments are divided into contracticle units: Sarcomeres
Main "threads" surrounded by?
Myofibrils enveloped by _sarcoplasmic reticulum_(stores Ca2+ ions)
Composition: Thin and Thick Filaments of Sarcomere
THIN filaments are chains of globular actin covered with threads of troponin and tropomyosin. THICK filaments are bundles of myosin molecules w/ organized head and tail region
Boundary line of single sarcomere?

also anchors the thin filaments
Line down the center (thick) of the sarcomere
M Line
Region with only Thick filaments?
H Zone
Region with only Thin Filaments?
I Zone
Region that spans entire length of thick filaments inc overlap
A Zone
Which portions contract? Which do not?
A Zone is not reduced in size but I Zone and H Zone are.
How initiated?
Msg from SNS sent via motor neuron. Depolarization of the motor neuron results in release of neurotrans which diffuse across synaptic cleft and bind to recptor sites on _sarcolemma_. If enough sites stimmed, all-or-nthing axn potential stimmed
Structure of Link b/t SNS and muscle
The NEUROMUSCULAR JUNCTION is composed of the _nerve terminal_/_synaptic bouton_ and the sarcolemma. The space b/t is the synaptic cleft
After initiation of a muscle contraction is...
SHORTENING of the sarcomere... Axn potential conducted along sarcolemma and T-sys.. into interior of muscle fiber. SR (SarcRet) releases Ca ions into Splasm. Ca binds to Trop...leaving actin binding sites free for myosin heads to bond. Thus thin filaments drawn to center of H zone
What allows for dissoc of myosin molecules?
ATPase activity; ADP&Pi are initially attached to myosin (ATP is hydrolyzed) but after powerstroke occurs ATP binds to myosin to allow for detachment of myosin from actin
What stage occurs after contractions?
Relaxation... when sarcolemmic recptors cease being stimulated, Ca ions returm to SR. Products of ATP hydrolysis are released from the myosin head, and new ATP binds to mysoin->myosin dissociates from THIN fil and sarcomere extends back. In absence of Ca ion Actin again covered by tropomyosin.
Stimulus Response?
Indiv fivers are all-or-nothing; must exceed threshold value. ..however more fibers mean graded response of muscle.
Continual low-grade contractions?
Simple Twitch
the response of a SINGLE muscle fber to a brief stimulus