Week 8 - Basics of Muscle Tissues Flashcards
What are the four special characteristics of muscle tissues?
Excitability
Contractility
Extensibility
Elasticity
What are the four basic muscle functions?
Movement of bones or fluids
Maintaining posture & body positioning
Stabilizing joints
Heat generation
Excitability
Ability to receive and respond to stimuli
Contractility
ability to shorten when stimulated
Extensibility
ability to be stretched
Elasticity
ability to recoil to resting length
Three types of Muscle Tissue
Skeletal
Cardiac
Smooth
Skeletal Muscle
Attaches to bone and skin
Striated
Voluntary
Long and multi nucleated
Cardiac Muscle
Walls of the heart
Striated
involuntary
Branching, intercalated discs
Smooth Muscle
Walls of hollow organs
Not striated
involuntary
Short, spindle, football shaped
Epimysium
surrounds entire muscle
Perimysium
surrounds fascicles
(groups of muscle fibers)
Endomysium
surrounds each muscle fiber (cell)
Muscles attach Directly -
epimysium fused to periosteum or perichondrium
Muscles attach Indirectly -
connective tissue extend beyond muscle as tendon or aponeurosis
Fascia
Skeletal muscle surrounded by fascia -
thin fibrous C.T. sheath for reinforcement, passage for nerves, blood vessels & attachment
Muscle - structure and organization
100s-1000s of cells wrapped in C.T. with blood and nerves.
Epimysium surrounds muscle
Fascicle - structure and organization
portion of the muscle
bundle of cells wrapped in C.T. sheath
Perimysium surrounds fascicle
Muscle Fiber Cell - structure and organization
Long, multinucleate with mitochondria
Striated appearance
Endomysium surrounds each cell
Sarcolemma - cell membrane
Sarcoplasmic Reticulum - stores Calcium
Muscle cell (muscle fiber) contains
many myofibrils, mitochondrion, wrapped in sarcolemma (membrane)
Myofibril
striations are evident
Sarcomere is a
muscle segment
Sarcomere components
Smallest contractile (functional) unit
Composed of myofilaments (actin and myosin)
Bands have names (A, H, I)
Z-Discs - edge of sarcomere
Z-Discs
Edges of sarcomere
How is the muscle organized from largest to smallest
Epimysium
Muscle
Perimysium
Fascicle
Endomysium
Sarcolemma
Muscle Fiber
Myofibril
Sarcomere
Filaments
Thick filament
Myosin
Thin filament
Actin
Thick filament has ..
Myosin protein
Myosin heads form Cross Bridges
Contain binding sites for Actin & ATP
ATPase Enzyme
ATPase enzyme
an enzyme that breaks down the third phosphate group off the ATP.
Breaking that bond releases the energy that myosin uses to make the muscle contraction work
Thin filament has
F (fibrous) actin protein consisting of G (globular) actin subunits
G-actin bears active sites for myosin head binding
Tropomyosin and troponin are regulatory proteins
What does troponin do
holds the tropomyosin in place (long strand of protein winding around actin)
What does tropomyosin do
Normally blocks the active site on the actin subunits
Membrane Potential is/has
Created by separation of charge
has Na+/K+ pumps & Gradients
has potential energy measured in volts (mV)
With Action Potential, which way does each ion want to move if a channel opens
Sodium moves in to the cell causing depolarization
Potassium moves out of cell causing repolarization
Motor Command
Cerebullum
Action Potential
a neural impulse; a brief electrical charge that travels down an axon
Origin of muscles
Is the more stationary point of attachment
Insertion point of muscles
Is the more mobile point of attachment
Belly of the muscle
Is the central portion of the muscle
Synapses
A gap between nerve cells
Neurotransmitter
a chemical used to carry a signal from an axon to a receptor cell to pass along a message
ATPase enzyme
enzyme that breaks 3rd phosphate off to change conformation of myosin head, and thus allows the myosin head to create cross-bridges within actin active subunits
Globular Actin subunits
the blueberry components of actin that bind together to form the F (fibrous) actin
Troponin
the site where calcium ions bind allowing troponin to change its grip on tropomyosin which moves tropomyosin to uncover the actin active sites
Actin
thin filament
Consists of two strands of actin subunits
twisted into a helix
has two regulatory proteins -
troponin
tropomyosin
Smooth ER
surrounds each myofibril
modified form of smooth ER called the sarcoplasmic reticulum
Terminal Cisternae
part of the sarcoplasmic reticulum (wider region)
Used for calcium storage
Sarcolemma
the plasma membrane of muscle fibers
triads
pair of terminal cisternae
T-Tubule
when an action potential travels down the sarcolemma of a muscle cell
Causes the the releases of calcium from the Sarcoplasmic reticulum
Excitement-Contraction (E-C) Coupling
AP transmission along sarcolemma leading to sliding of the myofilament then muscle contraction
Steps of the contraction cycle & relates to rigor mortis and muscle cramping
Rigor Mortis
Stiffness of death
