Skeletal and Muscular Systems Flashcards

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1
Q

what is the purpose of the musculoskeletal system

A
  • forms the basic frameowrk of the vertebrate body
  • muscles and bones work in close coordination to produce voluntary mvoement
  • physical support and locomotion are also functions
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2
Q

what is the purpose of the endoskeleton

A
  • serves as a framework within vertebraet systems
  • muscles are attached to the bones permitting movement
  • endoskeleton also provides protection by surrounding delicate vital organs in bone
  • rib cage protects the thoracic organs (heart and lungs)
  • skull and vertebral column protect the spinal cord
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3
Q

what is cartilage

A
  • one of two major components of the skeleton
  • type of connective tissue that is softer and more flexible then bone
  • retined in places where firmness and flexibility are needed: external ear, nose, walls of larynx and trachea and skeletal joints
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4
Q

what is responsible for synthesizing cartilage?

A

chrondrocytes

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5
Q

what is bone and the two types

A
  • bone is a specialized type of mineralized connective tissue that has the ability to withstand physical stress

Compact bone

  • dense and does not appear to have cavities when observed by nake dyee
  • bony matrix is deposited in structural units called osteons consisting of central microscopic channels called haversian canal
    • surrounded by concentric circles of bony matrix (calcium phosphate) called lamellae

Spongey Bone

  • much less dense and consists of inerconnecting lattice of boney spicules
  • cavities between the spicules are filled with yellow or red bone marrow
    • Yellow marrow is inactive and infiltrated by adipose tissue
    • Red marrow is involved in blood cell formation
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6
Q

what are osteocytes

A
  • two other cell types found in bone tissue are osteoblasts and osteroclasts

Osteoblasts:

  • synthesize and secrete the organic constituents of the bone matrix
  • once surrounded by matrix they mature into osteocytes

Osteoclasts:

  • large multinucleated cells involved in bone reabsorption wherein bone is broken down and minerals are released into the blood
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7
Q

explain bone formation

A
  • occurs by enochondral ossifcation or inramembranous ossifcation
  • endochondral ossifcation: existing cartilage is replaced by bone, long bones arise primarily through endochondral ossifcation
  • Intramembranous ossifcation: mesenchymal (embryonic or undifferentiaed) connective tissue is transformed into and replaced by bone
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8
Q

what is the axial skeleton and how are bones held together

A
  • axial skeleton is the basic frameowrk of the body, consists of skull vertebral column and rib cage
  • it is the point of attachment of the appendicular skelton which includes the bones of the appendages (limbs) and the pectoral and pelvic girdles
  • sutures or immoveable joints hold bones of skull together
  • bones that move relative to one another are held by moveable joints and are supported by ligments
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9
Q

what are ligaments and tendons

A
  • ligaments serve as bone-to-bone connectors
  • tendons attach skeletal muscle to bones and bend the skeleton at moveable joins
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10
Q

what are origins and insertion

A
  • point of attachment of a muscle to a stationary bone (proximal end of limb muscles) is the origin
  • the point of attachment of a muscle to a bone that moves (distal end of limb muscles) is the insertion
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11
Q

extension vs flexion

A

extension indicated the straightening of a joint

  • flexion refers to te bending of a joint
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12
Q

what does muscle tissue consist of and what are the 3 types of musle in mammals

A
  • muscle tissue consists of bundles of specialized contractile fibers fild be connective tissue
  • types: skeletal, smoother and cardian
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13
Q

what is involved in nervous control of the muscular system

A

axons of the pyramidal cells of the motor cortex which descend from the brain to synpase on lower motor neurons in the brain stem and spinal cord

  • pyramidal and extrapyramidal system
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14
Q

what is the pyramidal system and extrapyramidal system

A

pyramidal:

  • contains no intervening synpases
  • able to provide rapid commands to the skeletal muscles and various other organs

Extrapyramidal

  • issues somatic motor commands as a result of processing performed at the unconcious involuntary level
  • red nucleus located in the mesencephalon is the commponent of the extrapyramidal system primarily in control of skeletal muscle tone
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15
Q

what is skeletal muscle and what is it composed of?

A
  • responsible for voluntary movements and is innervated by the somatic nervous sytem
  • each fiber is a multinucleated cell created by the fusion of several mononucleated embryonic calls
  • each fiber contains myofibrils which divide into contractile sacromeres
  • myofibriles are envolved by sacromeres reticulum which stores calcium ions
  • cutoplasm of muscle fiber is called sarcoplasm and membrane called sarcolemma
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16
Q

what is the role of the sarcolemma and T system

A
  • specialized cell membrane which surrounds striated muscle fiber cells
  • capable of propogating an action potential and is connected to a sytem of transverse tubules (T system) oriented perpendicularly to the myofibrils
  • T system provides channels for ion flow throughout the muscle fibers and can propogate an action potential

*mitochondria very abundant in muscle cells bc high enregy requirement they are distributed along myofibrils

17
Q

what is skeletal muscle refered to as and why

A
  • striated muscle
  • bc has striations of light and dark bands
18
Q

what are sacromeres and how are the organized

A
  • composed of thick and thin filaments
  • thin filaments are chains of actin molecules and thick are organized bundles of myosin mol
  • organized as follows
  • Z line: defines the boundaries of a single sacromere and anchors the thin filaments
  • M line: runs down the center of the sacromere
  • I band: region containing thin filaments only
  • H zone: region containing thick filaments only
  • A band: soand entire length of thick filaments and any overlapping portions of thin

*when muslces contract the Z lines move towards eachother, A band is not rduced in size whereas the Z zone and I band are

19
Q

what triggers mucel contraction, what causes the generation of an action potential

A
  • stimulated be a message from somatic NS via motor neuron
  • link between the nerve terminal (synpatic bouton) and sarcolemme of muscle fiber = neuromuscular junction
  • space between the two is called the synpase or synpatic cleft
  • depolarization of the motor neuron results in relase of neurotransmitter (acetylcholine) which diffuses across synaptic cleft and binds to recepotor on sarcolemma
  • if enough receptors are stimulated the permeability of sarcolemma is altered and action potential is generated
20
Q

what occurs once an action potential is generated is muscle

A
  • conducted along the sarcolemme and the T system and into the interior of the muscle fiber
  • causes the sarcoplasmic reticulum to release calcium ions into sarcoplasm
  • calcium ions initiate the contraction of the sacromere by binding troponin C on actin filaments
  • allosteric changes occur in the proteins that allow myosin heads to bind to these sites on actin
  • use of energy allows the power stroke to occur pulling Z bands closer together

*actin and myosin slide past each other and the sacromere contracts

21
Q

what is rigor mortis

A
  • several hours after death muscles in the body contract and become rigid even w/o action potentials
  • rigidity is caused be absense of ATP which is required for the myosin heads to be released from acitn filaments
22
Q

what are the 5 major types of muscle contraction

A
  • isotonic, dynamic, concentric, eccentric and isometric
    isotonic: occurs when muscle shortens against a fixed load while tension on that msucle remains constant

dynamic: includes both concentric and eccentric, rults in change in length of the mucle with a corresponding change in tenion of that muscle

concentric: type of dynamic contraction where muscle fibers shorten and tension inc

eccentric: type of dynamic contraction where the muscle fiber lengthens and tenion inc

isometic: occurs when both ends of the muscle are fixed and no change in length occurs during contraction but tension inc

23
Q

explain the all or non respons of muscle fibers

A
  • only a stimulus above the threshold value can elicit a contraction
  • the strength of the contraction of a single muscle fiber cannot be increased regardless of the size of the stimulus
  • strength of muscle contraction of the entire muscle can be increased by recruiting more muscle fibers
24
Q

explain a simple twitch

A
  • response of a single muscle fiber to breif stimulus at or above threshold stimulus
  • consists of a latent period, contraction period and relaxation period
  • latent = time between stimulation and the onset of contraction
  • during time lab the action potential spreads along the sarcolemma and Ca2+ ions are released
  • after contraction period there is a breif relazation period in which muscle is unresponsibel to a stimulus (absolute refractory period)
25
Q

what is temporal summation

A
  • occurs when fibers of muscle are exposed to very frequent stimuli and muscle cannot fully relax
  • contractions begin to cobine becoming stronger and more prolonged
  • contractions become continuous when the stimuli are so frequent that muscle cant relax
  • known as tetanus ans is stronger than a simple twich of a single fiber
26
Q

what is tonus

A
  • state of partial contraction
  • muscles are never completely relaxed and maintain a partially contracted state at all times
27
Q

what occurs during strengous activity for energy

A
  • during stenious activity skeletal muscles convert glucose to pyruvic acid through glycolysis enabeling skeletal muslces to contrinue contracting even in absence of oxygen
  • lactic acid is generated when pyruvic acid is reacted with lactate dehydrogenase: allows the pyruvate to enter the cirtic acid cycle
28
Q

what is the cori cycle

A
  • during strenuous activity cori cycle converts lactic acid in liver to glucose for dischange into the bloodstream
  • once glucose is in the blood the muscles are able to use glucose as an immediate source of energy to rebuild glycogen reserves

*convresion of glucose into pyruvate in muscle cells is necessary for creation of ATP uring excersise does not involve the cori cycle

29
Q

what is smooth muscle and main artibutes

A
  • responsible for involuntary actions and is innervated by the autonomic enrvous system
  • found in digestive tract, bladder, uterus, and blood vessel walls
  • possess one centrally located nucleus and lack the striations of skeletal msucle
  • non striated, one nucleus cell, involuntary/autonomic NS, smooth continuous contractions
30
Q

what is cardiac muscle and main properties

A
  • muscle tissue of the heart, fibers possess characteristics of both smooth and skeletal muscle
  • has actin and myosin filaments arranged in sacromeres giving a striated appearance
  • only 1 or 2 centrally located nuclei
  • involuntary/autonomic NS
  • storng forceful contractions
31
Q

main properties of skeletal muscle

A
  • striated, multinucleated, voluntary/somatic NS, strong forceful contractions
32
Q

what is the primary energy reserve for muscle contraction

A

ATP, very little ATP is actually stored in muscles so other forms o energy must be stored and rapidly converted into atp

33
Q

what is crreatine phosphate

A
  • in vertebrated energy can be temporarily stored in a high energy compound: creatine phosphate