Muscles and Muscle Tissue Flashcards
What are the 3 types of muscle tissue in the
human body?
Skeletal, Cardiac, Smooth
Muscle tissue transforms ____________ energy into ____________ energy.
chemical, mechanical
Which types of muscle tissue are striated?
Skeletal + Cardiac
What is the function of each type of muscle
tissue?
Skeletal Muscle Tissue -responsible for voluntary
movements of the body, including actions such as walking, reaching, and
grasping objects.
Cardiac Muscle Tissue - found in the heart and is
responsible for pumping blood, ensuring circulation throughout the body.
Smooth Muscle Tissue -located in various internal
organs and structures, such as the walls of blood vessels and digestive organs,
and it functions involuntarily to propel substances, like blood and food, through
the body’s systems.
Which types are voluntary? Involuntary?
Skeletal - Voluntary
Cardiac - Involuntary
Smooth - Involuntary
List and define the 4 characteristics common to ALL types of muscle tissue
Excitability (responsiveness)- ability to receive/respond to stimuli by changing its membrane potential
Contractility- ability to forcibly shorten when stimulated
Extensibility- ability to stretch or extend - even beyond resting length
Elasticity- ability to recoil to resting length
List and define the 4 functions of muscle tissue.
- Produce Movement- – locomotion and manipulation
– contraction of the heart
– blood vessel dilation/constriction
– movement of all fluids/substances through tracts - Maintain posture and body position
- Stabilize joints
- Generate heat
In order to contract, skeletal muscles require
__________, ____________, and ____________.
Be familiar with the equation for cellular
respiration.
C6H12O6 + 6O2 —-> 6CO2 + 6H2O + ATP
Where does O2 come from? How about C6H12O6?
O2 comes from the air we breathe
C6H12O6 comes from the broken down carbohydrates in our diet
What happens to the CO2 and H20 created?
CO2 is breathed out
H2O is used by the body for maintaining hydration or is excreted through urination, or sweating
Define epimysium, perimysium, and endomysium. What type of structures are they? Know what each covers.
Epimysium- most external; dense irregular connective tissue surrounding the entire muscle; may blend with fascia
Perimysium- fibrous connective tissue surrounding fascicles (groups of muscle fibers)
Endomysium- most internal; fine areolar connective tissue surrounding each muscle fiber
When epimysium, perimysium, and endomysium are join together what do they become?
Together they become tendons that joins muscles to bones
Define origin and insertion. For practice, think
of a muscle. What is its origin? What is its
insertion?
Origin : the immovable or less movable bone
Insertion : the moveable bone
For the biceps brachii, origin is on the coracoid process of scapula, insertion
is merged into a tendon on the radius bone of the forearm
A tendon is an example of what type of
attachment?
Indirect : connective tissue wrappings extend beyond muscle as ropelike tendon
or sheetlike aponeurosis (more common!)
What is the other type of attachment (not
indirect)? Name a muscle that attaches this
way.
Direct ( Fleshy ): epimysium fused to periosteum or perichondrium
Example is the deltoid
What shape is a muscle cell? What are two
cellular organelles that a muscle cell would
have multiple of?
A muscle shape is long and cylindrical
They would have mitochondria and rough endoplasmic reticulum or myofibrils
Define sarcolemma.
plasma membrane of a muscle fiber
Define sarcoplasm.
cytoplasm of a muscle fiber
What are glycosomes?
Sarcoplasm contains many glycosomes – granules of stored glycogen
Define myoglobin.
a red pigment that stores Oxygen
What are myofibrils? How many might you
find in a single muscle cell?
Myofibrils : densely packed, rodlike elements
A single muscle fiber can contain 1,000s
Myofibrils are chains of _________________.
Sarcomeres (basic structural and functional unit of a muscle)
Draw out a sarcomere and label the following parts: A Band, I Band, H Zone, M Line, Actin, Myosin, Z Line. Do this over and over until you’ve got it down!
What bands make up the dark region? How about the light region?
A bands- dark regions
I bands- lighter regions
Why is the H Zone a lighter region within
the dark region?
H zone appears lighter since it contains only myosin filaments
Is actin the thin filament or the thick
filament? What about myosin?
Actin- thin filament
Myosin- thick filament
What are polypeptide chains?
long chains of amino acids bounded by peptide bonds
What types of polypeptide chains make up the thick filament? Within the thick filament, where can you find each type of polypeptide chain?
Thick Filaments - composed of the protein myosin. Each myosin molecule
contains 2 heavy and 4 light polypeptide chains.
Heavy chains intertwine to form myosin tail
Light chains form globular myosin heads
What is the function of the myosin head?
During contraction, myosin heads link thick and thin filaments together forming
cross bridges
Define G (Globular) Actin. What is its function?
Actin has kidney-shaped, polypeptide subunits called G (globular) actin
G actin subunits bear the sites for myosin head attachment during cross
bridge formation
Define F (Fibrous) Actin. What is its function?
G actin subunits link together to form long, fibrous F actin
2 F actin strands twist together to form a thin filament
List the 2 regulatory proteins bound to actin. What is each of their specific functions?
Tropomyosin and Troponin - regulatory proteins bound to actin that control
muscle contraction
Tropomyosin - rod-shaped protein, spiral about the actin core and block
myosin-binding sites
Troponin - globular protein, able to bind to 1-actin, 2-tropomyosin, 3- calcium
What role does the protein elastin play?
How about dystrophin?
Elastin’s main function is to allow tissues in your body to stretch out and
shrink back .
Elastic Filament - composed of protein titin; holds thick filaments in place;
helps to resist excessive stretch and assists with recoil
Dystrophin - structural protein that links the thin filaments to the integral
proteins of the sarcolemma
Broadly, what are the muscular dystrophies?
What are some specific symptoms of
Duchenne Muscular Dystrophy (DMD)? What
protein is impaired in DMD? What does
impairment of this protein cause in terms of
muscle function? Do you remember how
scientists are attempting to cure DMD? I
talked about it in class!
What is sarcoplasmic reticulum? What is its
function?
Sarcoplasmic Reticulum - network of smooth endoplasmic reticulum
tubules surrounding each myofibril
- Stores and releases calcium on demand
- Functions in regulation of intracellular calcium levels
- Most tubules run longitudinally
What is a terminal cistern? Where can you
find them?
Terminal Cisterns - SR tubules that form perpendicular cross channels
at the A-I band junction; always occur in pairs
What is a T-Tubule? Where can you find them? What is its function?
Tube formed by protrusion of the sarcolemma deep into the cell’s
interior – pass from 1 myofibril to the next
Occur at A-I band junction - between terminal cisterns
T Tubules allow electrical nerve transmissions to reach deep into
the interior of each muscle fiber and trigger the release of calcium
Together, the 2 terminal cisterns and the T-
Tubule are known as the __________?
Triad - area formed from the terminal cistern of one sarcomere, a T tubule, and
the terminal cistern of the neighboring sarcomere
Protruding proteins from the T-Tubules act as what type of sensors?
voltage sensors – change shape in response to an electrical current
Protruding proteins from the SR act as what type of sensors?
form gated channels through which Calcium can be released
What happens when an electrical impulse
passes through the triad?
T tubule proteins change shape, SR proteins change shape, and calcium is released into the cytoplasm
Contraction is generation of ___________ by
activation of myosin’s _____________________.
force, cross bridges
Which myofilament slides in the sliding filament model? Do actin and myosin change their individual lengths?
If not, how does the sarcomere change length?
The actin filaments slide relative to the myosin filaments
Actin and myosin do not change their lengths
Sarcomere Length Change - Sarcomeres, the basic structural units of
muscle fibers, change length as a result of the sliding of actin and myosin
filaments. When a muscle contracts, the sarcomeres shorten, bringing the Z
lines closer together. When a muscle relaxes, the sarcomeres lengthen, and
the Z lines move farther apart.
What happens with Z Discs, I bands, H Zones
and A bands when the muscle contracts
Ratcheting action shortens the muscle fiber
- Z discs are pulled toward the M line
- I bands shorten
- H zones disappear
- A bands move closer together
