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ch 10
10, ect
84
Anatomy
Undergraduate 2
10/30/2014

Additional Anatomy Flashcards

 


 

Cards

Term
What are the general functions of muscle tissues?
Definition

Movement-sometimes locomotion, sometimes movement within a given area 

Posture-maintains body in stable positions

Thermogenesis (heat production)-as much as 85% produced by contractions

Regulating orgain volume-contraction of sphincters may prevent outflow of contents of hollow organ 

Term
Thermogenesis
Definition

Heat production-as much as 85% of body heat is from muscle contractions 

Term
What are the characteristics of muscle tissue?
Definition

Excitability (irritability)

Contractility

Extensibility

Elasticity

Term
Excitability(irritability)
Definition

ability to recieve and respone to stimuli

 

Term
Contractility
Definition

ability to shorten and thicken 

Term
Extensibility
Definition

ability to stretch 

Term
Elasticity
Definition

ability to return to original shape after stretching 

Term
Types of Muscle Tissue
Definition

Sketetal-striated, voluntary muscle (100's nuclei in perphery)

Smooth-visceral (organs), involuntary muscle (1 nuclei in center)

Cardiac-striated, involuntary (1 nuclei in center)

Term
Epimysium
Definition

Fibrous connective tissue sheath that envelops each muscle 

Term
Perimysium
Definition

partitions each muscle into fascicles or bundles of fibers 

Term
Endomysium
Definition

extension between individual muscle fibers (muscle cell) 

Term
Tendon
Definition
Strong, tough cord of dense connective tissue
Continuous w/ entends from eipmysium, perimysium, endomysium 
Continous w/ inserts into the periosteum 
Term
Aponeurosis
Definition

Broad flat sheet of fibrous connective tissue continous at one border with fibrous wrapping of muscle and at other border with fibrous covering of adjacent structure, usually another muscle

  • in the cat, linea alvea, it connects to external oblique, underneath it is rectus abdominus 
Term
Tendon Sheath
Definition

Tube of fibrous connective tissue that enclose certain tendons (wrist and ankle)

  • synovial membrane line tendom sheath->fluid filled cavity which reduces friction 
Term
Superficial fascia (subcutaneous layer)
Definition
  • Loose connective tissue that separates muscle from skin
  • Stores water and fat
  • Forms layer of insulation 
  • Provides mechanical protection against blows
  • Provides pathway for nerves and blood vessels to enter and exit muscles 
Term
Sarcolemma
Definition

Cell membrane of muscle fiber 

Term
Sacroplasm
Definition

Cytoplams of muscle fiber 

Term
Sarcoplasmic reticulum
Definition
smooth endoplasmic reticulum; encircles each myofibril; stores calcium, contains calcium release channels (pores)
Term
Myofibrils
Definition

fine fibers packed close together in sacroplams; consist of 3 kinds of myofilaments 

Term
Sarcomere
Definition

Section of myofibril between Z lines 

Term
Myofibril
Definition
Made up of myofilaments
Term
Myofilaments
Definition

Thick filament-myosin molecules

Thin filaments-actin, tropomyosin, and troponin molecules arranged in complex fashion

Elastic filaments-titin biggest protein in the body 

Term
Thick filaments
Definition

myosin molecules

heads of myosin are cross bridges of thick filaments

Term
Thin filaments
Definition

made up of actin, tropomyosin, and troponin molecules arrange in complex fashion

contains myosin-binding site

Term
Elastic filaments
Definition

Made up of titin biggest protein in the body (connectin)

Third most plentiful protein after action and myosin in muscle fibers

Anchors thick filaments Z discs; stabilizes thick filament 

50 times larger than average protein 

Connects Z discs to the M line of sarcomeres, stabilizes thick filaments 

Can stretch to 4 times its resting length; responsible for extensibility and elasticity of myofibrils 

Term
A band (anisotropic)
Definition

Composed of both thick and thin filaments. Appear as dark strips (EM microscope)

Term
H zone
Definition

Composed of only thick filaments

Run across midsection of each dark A band 

Term
M line
Definition

Divides H zone

Formed by protein molecules that connect to protein in neighboring M lines->connecting adjacent thick filaments 

Term
I bands (isotropic)
Definition

Composed only of thin filaments 

Appears as light stripes 

Term
Z discs
Definition

Extends across center of each light I band

Regions of dense material; separates sarcomere

Term
Alpha Actninin
Definition

Structural proteins in muscle fiber 

Found in Z disc-binds actin to titin 

 

Term
Myomesin
Definition

Forms M line of sarcomere

Binds to titin and to protein adjacent to M line 

Term
Nebulin
Definition

wraps around entire length of each thin filament; anchors thin filaments to Z discs 

Term
Dystrophin
Definition

Links thin filament to integral membrane protein in sarcolemma, which are attached to proteins in surrounding connective tissue endosyium->structural support, helps to transmit tension from contracting sarcomere to tendons 

Term
Transverse tubules
Definition
Tunnel like enfolding's of sarcolemma in region of Z discs; on either side are dilated end sacs of SR called terminal cisterns
Term

Terminal cisterns

 

Definition
lay on either side of transverse tubules; are dilated end sacs of SR
Term
Triad
Definition

Transverse tubules and 2 cisterns on either side; triple layered structure consisting of T tubule sandwiched between sacs of SR 

Term
Motor Unit
Definition

one motor neuron together with all the skeletal muscle fibers its supplies; number of muscle fibers per unit varies

Examples: 

Precise movement: one motor neuron supplying fewer muscle fibers (voice: 2-3 muscle fibers/motor unit)

Gross movement: greater number of muscle fibers supplied by a single motor neuron (bicepts brachii as many as 2000/motor unit)

Term
Describe precise movement
Definition

 

 

 

 

one motor neuron supplying fewer muscle fibers

example:(voice: 2-3 muscle fibers/motor unit)

Term
Describe Gross Movement
Definition
Greater number of muscle fiber supplied by a single motor neuron (biceps brachii as many as 2000s/motor unit)
Term
Neuromusuclar (myoneural) Junction
Definition

o   Channels open for Na+ to diffuse into muscle fiber generating action potential which leads to muscle contraction

Term
Sliding filament theory
Definition

cross bridges of thick filaments (myosin) attach to thin filaments (actin) and pull them toward the middle of the sarcomere 

Term
What happens in the uncontracted state?
Definition

Calcium is stored in SR 

ATP is attached to cross bridges 

Tropomyosin-troponin complex is covering the myosin binding site on actin 

Term
Describe Contraction
Definition

-Upon stimulation by nerve impulse acetyoline is released by motor axon synaptic end bulbs

-Ach diffuses across myoneural junction and initiates an action potential in the muscle fiber (movement of Na into fiber and K out of fiber)

-impulse is conveyed from T tubules to SR-> induces release of Ca by opening Ca release channels 

-Ca ions combine with troponin causing troponin-tropomyosin complex to move which exposes the myosin-binding site on the actin molecule 

-Energy release from hydrolyzed ATP is used for the attachment of myosin cross bridges to myosin-binding sites on actin

-Energy is then used to pull actin filamemts inward (power stroke) resulting in sliding of thin filaments past thick filaments

-sliding draws Z discs toward each other, sarcomere shortens, muscle fiber contracts, muscle contract

 

Term
Describe what happens after action potential?
Definition

-ACh is inactivated by acetycholinestrase (AChe)

-Ca is transported back into SR

-Tropomyosin-troponin complex reattaches to actin

-Myosin cross bridges seperate from actin

-ATP is resynthesized; muscle relaxes 

Term
How do muscle fibers produce ATP for muscle contraction?
Definition

1. From creatine phosphate

2. By anaerobic respiration

3. By aerobic respiration 

*note: average cellular levels of ATP and creatine phosphate together provide enough energy for muscles to contract maximally for about 15 sec. 

Term
Phosphogen System
Definition

Part of muscle metabolism 

-muscle fibers contain creatine phosphate

-creatinine phosphate->creatine and phosphate and energy

-Phosphate and energy can be used to remake ATP

-Creatine Phosphate is 3-5 times more plentiful than ATP

-together stores of creatinine phosphate and ATP provide enough energy for muscles to maximally contract for 15 sec. 

Term
Creatine Phosphate
Definition

Storage form of energy in muscle fiber 

Creatine:synthesized in the liver, kidneys, and pancreas and transported to muscle fibers

Creatine kinase (CK) catalyzed the additon/removal of phosphate 

Term
Glycogen-lactic acid system
Definition

Part of muscle metabolism

-when creatine phosphate is gone:

  • glycogen is broken down and glucose is catalyzed
  • if oxygen is not available, anaerobic respiration takes place in the form of glycolysis with formation of lactic acid and some energy (for 2 mins of max muscle activity)
  • lactic acid diffuses into blood; liver can convert lactic acid back into glucose 
Term
ATP from Anaerobic Cellular Respiration
Definition

Aerobic system 

  • longer activity depends on aerobic process
  • with oxgen available cellular respiration occurs to produce ATP, carbon dioxide and water
  • oxgens comes from blood and is bound/released from myoglobin inside muscle fibers
  • Provides ATP for prolonged activity as long as oxygen and glucose are available  
Term
Aerobic Respiration in Muscle Fibers
Definition

-Maximum rate of oxygen consumption is called max oxygen uptake; affected by gender, age, size, training

-After heavy muscle activity, heavy breathing continues to repay oxygen used in activity (oxygen debt or recovery oxygen consumption)

Term
All-or-none Law
Definition

Muscle cells either contract with all force possible under existing conditions or do not contract at all 

Term
Tonic Contration (tone, tonus)
Definition

-Continual, partial contractions produced by stimltaneous activation of small form of motor units, followed by relaxation of their fiber and activation of another group of motor units 

-Muscle tone-keeps skeletal muscles firm but is not strong enough to produce movement 

-Flaccid-state of limpness in which muscle tone is lost

-Muscle spindles and neurotendinous end-organs: detect degree of muscle stretch 

Term
Flaccid
Definition

State of limpness in which muscle tone is lost in tonic contraction 

Term
Isotonic contraction
Definition

-a muscle shortens but its tension remains constant

-isotonic contraction produce movement

-Two types:concentric and eccentric 

Term
Concentric Contractions
Definition

-shortening of a muscle that results in reducing the angle at a joint

-example: picking up a book requires concentric contraction of biceps brachii muscle 

Term
Eccentric Contractions
Definition

Controlled lengthening of a muscle during contraction that results in increasing the angle at a joint (repeated contractions produce more muscle damage that concentric)

Example: lowering the book requires eccentric contraction of the bicep brachii 

Term
Isometric Contractions
Definition

Muscle length remains unchanged but tension within muscle increases; isometric contractions "tighten" muscles but do not produce movements: energy expended 

Example: holding a book steady using outstretched arm

     -the book pulls the arm downward stretching the shoulder and arm muscle. The isometric contraction of these muscles counteracts the stretch 

Term
Twitch Contration
Definition

A quick, jerky contraction in response to single stimulus; consists of 3 phases-this is rare in normal body

1.latent period

2.contraction phase

3.relaxation phase

 

Term
Tetanic contraction (tetanus)
Definition

Sustained smooth contraction produced by series of stimuli bombarding muscle in rapid succession 

Term
Treppe(staircase phenomenon)
Definition

series of increasingly stronger contractions in response to constant strength stimuli applied at rate of 1 or 2 per second 

Term
Contracture
Definition

incomplete relaxation after repeated stimulation 

Term
Fatigue
Definition

failure of muscle to contract in response to strongest stimuli after repeated stimulation; true muscle fatigue seldom occurs in body 

Term
What happens prior to muscle contraction?
Definition

-action potential travels down axonaterminal bulb (neuron)

-influx of Ca2+

-Fusion of vesicles with neurolemma release of acetylcholine into the neuro muscular junction 

-acetylcholine binds to receptors on motor end plate

-initation of action potential in muscle fiber (Na+ flows in, K+ flows out)

 

Term
Steps in a contraction
Definition

1. Latent period (2 sec): muscle action potential sweeps over the sarcolemma inducing release of Ca2+ from the SR

2. Contraction period (10-100msec): Ca2+ binds to troponin: myosin binding sites on actin are exposed and cross bridges form (ATP,ADP)

3. Relaxation period (1-100msec): Ca2+ is actively transported back into SR, myosin head detach from actin (ATP), myosin binding sites are covered by tropomyosin and tension in the muscle fiber decreases

Term
Myogram
Definition
A record of a contraction produced by direct stimulation of a motor neuron or a muscle fiber
Term
Wave Stimulation
Definition

A second stimulus occurs before the skeletal muscle fiber has relaxed. The second contraction will be stronger than the first. Must occur after the refractory period 

Term
Unfused(incomplete) Tetanus
Definition

sustained but wavering contraction when a skeletal muscle fiber is stimulated at a rate of 20-30 times per second such that is can partially relax between stimuli 

Term
Fused (complete) Tetanus
Definition

sustained contraction. A muscle fiber is stimulated 80-100 times per second; no relaxation; individual twitches can't be detected 

Term
Refractory period
Definition

Required recovery period between consecutive stimulations of nerve of muscle fibers. If two stimuli are applied during this time only the first stimululs will induce a response. Why? Time need to restore K+ and Na+ to their appropriate sides of the sarcolemma by Na+/K+ pumps

   -resting potential state 

Term

Why is the peak tension generated during fused tetanus 5-10 times larger than the peak tension produced during a single twitch? 

Definition

There is a buildup of Ca2+ levels in the sarcoplasms as more and more Ca2+ is released from the SR; also the elastic components (connective tissue, tendons) aren't given time to spring back between contractions 

Term
Red muscle fibers
Definition

high myoglobin content; more mitochondria and blood capillaries 

Term
White muscle fibers
Definition
low myoglobin content; less mitochondria and blood capillaries
Term
Slow Oxidative Fibers
Definition

Type one-slow twitch or fatigue-resistant fibers

-appear as red (lots of myoglobin), many blood capillaries, high capacity to generate ATP by aerobic system 

-Split ATP at slow rate so have slow contraction velocity

-resistant to fatigue; capable of prolonged, sustained contractions

-Found in head and neck muscle-maintain posture

-Needed for long endurance activities-running a marathon 

Term
Fast Oxidative
Definition

Type 2-fast-twitch A or fatigue-resistant fibers

-largest fibers

-large amounts of myoglobin and many blood capillaries need oxygen for aerobic respiration, dark red

-generates a lot of ATP by aerobic cellular respiration-hence moderatly resistant to fatigue

-High intracellular glycogen levels-also generates ATP by anaerobic glycolysis 

-3-5 times faster ATPase activity in their myosin head com paerd to SO fibers 

-contribute to activities such as walking and sprinting 

Term
Fast Glycolytic Fibers
Definition

type 2-fast twitch B or fatigable fibers

-appear white

-contain large amounts of glycogen

-generates ATP by anaerobic process-so fatigue easily 

-split ATP fast, so strong rapid contraction

-adapted for intense anaerobic movements of short duration 

Example: weight lifting or throwing a ball

Term
What happens after 30 mins of exercise?
Definition

after the first 30 mins of exercise the body runs out of its glycogen storage and then turns mainly to what is left of glucose in the blood, then to fat and amino acids derived from muscle protein 

Term
Anatomy of Cardiac Muscle
Definition
  • fibers are quadrangular shape and single nucleus
  • Same bands and composition of actin and myosin as skeletal muscle due to striation
  • Fibers branch and interconnect with each other; intercalated discs are irregular transverse thickenings of sarcolemma that connects neighboring fibers
  • Two networks of fibers: one in atria and one in ventricles; allows entire network to contract together 
Term
Physiology of Cardiac Muscle
Definition
  • Contracts and relaxes an average 75 times/minute thus requiring constant oxggen supply 
  • Contains more mitochondria than skeletal muscle; depends on aerobic system to supply
  • Cardiac muscle can contract without extrinsic stimulus; has specialized conducting network within heart (autorhythmicity)
  • Remains contracted 10-15 times longer than skeletal muscle but also has long refractory period 
Term
Smooth Muscle Anatomy
Definition
  • Smaller fiber than skeletal; thickest in middle and tapered at end with single nucleus
  • Contains thick and thin filaments but not arranged in sarcomeres as in striated muscle
  • Contains intermediate filaments which attach to structures called dense bodies(Similar to Z discs); some dense bodies are scattered in sarcoplasm and some attach to sarcolemma
  • Bundles of intermediate fibers stretch from one dense body to another; actin/myosin based contraction causes intermediate filaments to pull on dense bodies causes lengthwise shortening of muscle fiber 
Term
Visceral smooth muscle
Definition

Single unit-most common; forms part of walls of small arteries and veins and hollow viscera such as stomach, intestines, uterus and bladder; contains gap junctions which allows stimulation of many fibers at once

-entire muscle contracts as one unit

Term
Multiunit smooth muscle
Definition

individual fibers each with own motor neuron terminals and with few gap junctions between neighboring fibers; stimulation causes contraction of only one fiber; found in walls of large arteries, in large airways of lungs, in arrector pili muscles, and in radial and circular muscles of the iris

-each muscle fiber contracts individually, multiple contracting units per smooth muscle 

Term
Physiology of Smooth Muscle
Definition
  • Contraction starts more slowly and lasts longer than striated muscle; can shorten and stretch more than striated
  • No T tubulus and Ca enters through sarcolemma as well as released from SR
  • Contains calmodulin (analogous to troponin) and myosin light chain kinase which are needed for myosin binding to actin
  • Ca moves slowly out of cell, which delays relaxation resulting in prolonged muscle tone
  • Smooth muscle contraction is controlled by the automatic nervous system (involuntary)
Term
Deep fascia
Definition
layer of dense fibrous connective tissue underlying superficial fascia; extensions of deep fascia form epimysium ect; and also enclose viscera, gland, blood vessels, and nerves
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