Flashcards in 02 Muscular System Deck (44):
Functions of the Muscle Tissue
-Producing body movements
-Stabilizing body positions
-Regulating organ volumes
~Bands of smooth muscle called sphincters
-Movement of substances within the body:
~Blood, lymph, urine, air, food and fluids, sperm (get pushed through the body by the muscle tissue)
~Involuntary contractions of skeletal muscle (shivering)
Properties of Muscle Tissue (5)
Ability to respond to stimuli and produce electrical signals.
~External/Internal (scared and run)
Ability to shorten and generate force once excited (bicep curl)
Ability to stretch without damaging the tissue (leg extension)
Ability to return to normal length after being exposed (hamstring stretch - back to normal)
Ability to produce heat energy (occurs anytime there is muscular contractions)
Typically on the fixed bone (not moving) usually more proximal than the insertion
Ex. Bicep brachii is attached to the scapula (origin) which is also connected to the humerus and the radius (insertion) which is the bone that will move. As the bicep contracts the muscle will shorten and you will see the forearm flex
3 types of muscle tissue
-Attached to bone, skin or fascia
-Striated with light and dark bands visible with scope
~Result of arrangement of different proteins
-Voluntary control of contraction and relaxation
-Striated in appearance
~Authorhythmic because of built in pacemaker
-Single nucleus per cell
-Attached to hair follicles in skin (makes your hair stand up)
-In walls of hollow organs- blood vessels & GI track
-Nonstriated in appearance
Parallel arrangement of fascicles
fascicles parallel to longitudinal axis of muscle: terminate at either end in flat tendons
(example: stylohyoid muscle)
Fusiform arrangement of fascicles
fascicles nearly parallel to longitudinal axis of muscle: terminate in flat tensions; muscle tapers towards tendons, where diameter is less than at belly (ex. digastric muscle)
fascicles in concentric circular arrangements from sphincter muscles that enclose an orifice (opening) (ex. orbicularis couli muscle)
fascicles spread over broad area converge at thick central tendon; gives muscle a triangular appearance (pectoralis major muscle)
Short fascicles in relation to total muscle length; tendon extends nearly entire length of muscle
fascicles are arranged on only one side of tendon
(ex. extensor digitorum longus muscle)
fascicles are arranged on both sides of centrally positioned tendons (ex. rectus femurs muscle)
fascicles attach obliquely from many directions to several tendons (ex. deltoid muscle)
Muscle Composition and Structure
Skeletal muscle bundle - Fascicles - Muscle Fibers - Myofibrils - Sarcomeres - Filaments
Epimysium and the other name for it?
covers the muscles. Fascia
muscle composed of many bundles of muscle fibers
what fascicles are covered by
surrounds the individual muscle fibers
what are the connective tissue structures?
Epimysium, Perimysium, and endomysium.
Run the length of the muscle belly to form the tendon which connects the muscle to the bone
-what each muscle fiber is composed of.
-contractile elements of skeletal muscle
-Composed of many sarcomeres which extend from z-line to z-line
function unit of contraction
What are sarcomeres and myofibrils composed of?
thats what give muscles the striated appearance
2 types of filaments?
thick filaments (myosin) and thin filaments (actin, troponin, tropomyosin)
Actin are pull across our myosin
Filaments are composed of what?
Contractile and regulatory proteins
Proteins in the muscle?
-Each molecule resembles two golf clubs twisted together
-Myosin heads- golf clubs (cross bridge) extend toward thin filaments pulling all together towards the M line.
-Everything is held in place by the M line proteins
What are thin filaments made up of?
Actin, troponin, and tropomyosin
myosin binding site is covered by this in relaxed muscle.
-thin filaments are held in place by the z-line.
-one z-line to the next z-line = 1 sarcomere
Functional unit of skeletal muscle
Functional unit of skeletal muscle is the motor unit composed of what?
-single motor neuron
-muscle fibers that it innervates (different for different muscles)
Muscular contraction cycle
-never impulse travel down the motor neuron to axon terminal
-neurotransmitter acetylcholine (ACh) is released into the synaptic cleft (space between neuron and axon terminal
-ACh binds to receptors on the motor end plate of the muscle fiber
-Electrical impulse transmitted to the muscle fiber: spreads through the cell membrane of the muscle and down the t-tubles (surround muscle fibers)
-triggers sarcoplasmic reticulum to release Ca2+ (calcium) into muscle fibers
-Calcium binds to troponin; tropomyosin moves away to uncover binding sites on actin
-Myosin (thick fibers) heads bind to actin
-Myosin heads pivot so that actin is pulled to shorten the sarcomere length (contraction)
-To stop the muscle contraction acetylcholinesterase (AChE) breaks down ACh in the synaptic cleft
-Calcium (Ca2+) goes back into the sarcoplasmic reticulum
-Troponin and tropomyosin cover the binding sites on actin
-Sarcomere returns to its resting length (elasticity)
Two different contraction?
Isotonic contraction and two types?
A load is moved - muscle contracts and changes length
Concentric & Eccentric Contraction
A muscle shortens to produce force and movement
a muscle lengthens while maintaining force and movement (controlling movement to lengthen)
Resistance greater than force