Muscles Flashcards
What are the four basic types in the human body?
1) Muscle
2) Epithelial Tissue
3) Nerves
4) Connective Tissue
What are the three types of muscle?
1) Skeletal muscle
2) Cardiac muscle
3) Smooth muscle
What is the primary function of muscle tissue?
To produce movement
Muscle tissue consists of muscle cells that are ____________
Specialized for contraction.
Main function of Skeletal Muscle
Moves the body by pulling on our bones, making it possible for movements.
Function of Cardiac muscle
pumps blood through the cardiovascular
system.
Function of Smooth muscle (2x)
pushes fluids and solids along the digestive tract and other internal organs and regulates the diameters of small arteries and respiratory bronchioles.
Skeletal Muscle Functions (6x)
1) Producing Movement
2) Maintaining Posture and Body Position
3) Supporting Soft Tissues
4) Guarding Body Entrances and Exits
5) Maintaining Body Temperature
6) Storing Nutrients
Skeletal Muscle Function: Producing Movement (How?)
In general, skeletal muscle contractions pull on tendons to move our bones.
Skeletal muscle actions range from simple motions, such as extending the arm or breathing, to the highly coordinated movements of swimming or piano playing.
Skeletal Muscle Function: Maintaining Posture and Body Position (How?)
Tension in our skeletal muscles maintains body posture—for example, holding your head still when you read a book or balancing your body weight above your feet when you walk.
Skeletal Muscle Function: Supporting Soft Tissues (How?)
Layers of skeletal muscle make up the abdominal wall and the pelvic floor cavity.
These muscles support the weight of our visceral organs and shield our internal tissues from injury.
Skeletal Muscle Function: Guarding Body Entrances and Exits (How?)
Skeletal muscles called sphincters encircle the openings of the digestive and urinary tracts. These muscles give us voluntary control over swallowing, defecating, and urinating.
Skeletal Muscle Function: Maintaining Body Temperature (How?)
Muscle contractions use energy, and whenever energy is
used in the body, some of it is converted to heat. The heat
released by working muscles keeps body temperature in
the range needed for normal functioning.
Skeletal Muscle Function: Storing Nutrients (How?)
When our diet contains too few proteins or calories, the proteins in skeletal muscles are broken down, and their amino acids are released into circulation to supply the
energy and nutrient needs of the entire body. The liver can use some of these amino acids to synthesize glucose, and others can be broken down to provide energy.
Individual Muscle Cell (One Muscle Fiber) is enclosed by ______________
Endomysium
Muscle Fascicle (Bundles of Muscle Cells) is enclosed by
Perimysium
Skeletal muscle tissue is enclosed by
Connective tissue, Epimysium
The Organization of Skeletal Muscle
1) Muscle Tissue
2) Muscle Fascicle
3) Individual Muscle Cell
The Organization of Skeletal Muscle Membrane
1) Epimysium
2) Perimysium
3) Endomysium
A skeletal muscle tissue consists of _______________
multiple fascicles (bundles of muscle fibers)
Each muscle fiber/cell has many _______________, as well as _______ and other ________
Superficial nuclei, as well as mitochondria and other organelles
What forms a tendon or aponeurosis?
Collagen fibers of the epimysium, perimysium, and endomysium come together to form
What is aponeurosis?
A sheet of pearly white fibrous tissue that takes the place of a tendon in flat muscles having a wide area of attachment
Where do tendons and aponeuroses attach to skeletal muscle? Result?
Where they contact the bone, the collagen fibers extend into the bone matrix, providing a firm attachment. As a result, any contraction of the muscle pulls on the attached bone.
Where do tendons and aponeuroses attach to skeletal muscle? Result?
The collagen fibers extend into the bone matrix, where they contact the bone, providing a firm attachment. As a result, any contraction of the muscle pulls on the attached bone.
Muscle contractions require a small quantity of energy (T/F)
False
What is the role of Nerves in their relation to Muscles?
Simtulates the Muscles to contract (tells the muscles to move)
An extensive vascular network delivers the oxygen and nutrients and carries away the metabolic wastes generated by active skeletal muscles. (T/F)
True
Why are skeleton muscles often called voluntary muscles?
We have voluntary control over their contractions
How are skeleton muscle fibers different from the “typical” cells?
1) Size (Skeleton muscle fibers are enormous)
2) Multinucleated (Each cell contains hundreds of nuclei)
3) Banded/Striated
Why are skeleton muscle fibers multinucleated?
To ensure faster production of proteins required for normal muscle contraction.
Myoblasts (Desc)
Groups of embryonic cells
Myoblasts (Func)
Fuses to form individual multinucleated skeletal muscle fibers. Each nucleus in a skeletal muscle fiber comes from a single myoblast
Microsatellite (Desc)
Some myoblasts do not fuse with developing
muscle fibers. They remain in adult skeletal muscle tissue as microsatellite cells.
Microsatellite (Func)
After an injury, microsatellite cells may enlarge, divide, and fuse with damaged muscle fibers to assist the repair.
Myofibrils (Desc)
Each muscle fiber contains hundreds to thousands of
cylindrical structures called myofibrils.
The striations are due to _________________
the precise arrangements of thin (actin) and thick (myosin) filaments in the myofibrils.
What is the function of T tubules?
To release Calcium and reabsorb Calcium
Sarcolemma (DESC)
AKA plasma membrane of a muscle fiber surrounds the sarcoplasm or cytoplasm of the muscle fiber.
Sarcoplasmic Reticulum (DESC)
Membrane complex in skeletal muscle fibers forms a tubular network around each myofibril,
Transverse tubules (DESC)
Contain extracellular fluid (high in Ca and Na ions). They are continuous tubes of the sarcolemmal membrane that run through (transversely) the muscle fiber
Muscle fibers contain
1) Sarcolemma
2) Sacroplasm
3) Myofibril
4) Sarcoplasmic reticulum
5) Transerve tubules
Each myofibril is covered by
sarcoplasmic reticulum and branches of T tubules.
Myofibrils consist of bundles of protein filaments called
myofilaments
two types of myofilaments:
thin filaments (actin), and thick filaments (myosin).
Scattered among the myofibrils are
mitochondria and granules of glycogen, the storage form of glucose.
Mitochondrial activity and glycolysis (glycogen breakdown to glucose) provide _________ in the form of ________ for ___________
provide energy in the form of ATP for muscular contractions.
The active shortening of myofibrils result in
➠ skeletal muscle fiber contraction.
The sliding filaments result in
shortening of myofibrils
SR is similar to
the smooth endoplasmic reticulum of other cells.
The SR is specialized for
the storage and release of Calcium
Skeletal muscle fibers actively transport
Calcium into the SR.
Sarcomere contains (4x)
(1) thick filaments, (2) thin filaments, (3) proteins that stabilize the
positions of the thick and thin filaments, and (4) proteins that regulate the interactions between thick and thin filaments
The arrangement of thick filaments and thin filaments produces
the characteristic banding of myofibrils and muscle tissue as a whole.
Bands of the Sarcomere
1) A bands
2) I bands
Each sarcomere has dark bands called
A bands
Each sarcomere has light bands called
I bands
For each sarcomere, there is one ___ zone
H-band (H-zone) at the center of the A band.
I bands only have _____ filament
thin (actin)
A bands have __________ filament
thin and thick
H bands have ________ filament
thick
H bands __________ A bands
bisects
M lines are located
in the middle of H bands
Z lines ______ I bands
bisects
Thin filaments aka
Actin
Thick filaments aka
Myosin
The Sliding Filament Theory (4x)
The thin filaments are sliding toward the center of each sarcomere,
alongside the thick filaments
(1) the H bands and I bands narrow
(2) the zones of overlap widen
(3) the Z lines move closer together
(4) the width of the A band remains constant.
During a contraction, sliding occurs in every sarcomere along the myofibril. Results in (3x)
the myofibril gets shorter. Because myofibrils are attached to
the sarcolemma at each Z line and at either end of the muscle fiber, when myofibrils get shorter ➠ so does the muscle fiber ➠ so does the muscle tissue
Muscular Activity Is under
Neural Control
Muscle tissue has
excitability & contractility
What is action potential?
Neurotransmission between neurons
Action potential arrives at
the end of neuron axon
Neurotransmitter release from where
(from axon terminal)
Neurotransmitter binds to receptor
(motor end plate in muscle cells)
Action potential generated where
(in muscle)
Action potential causes
Ca2+ release
Sliding filaments causes what
(contraction)
Sliding filaments causes muscle contraction and generates what
muscle tension
Muscular Activity steps (8x)
- Neurotransmission between neurons (action potential)
- Action potential arrives at the end of neuron axon
- Neurotransmitter release (from axon terminal)
- Neurotransmitter binds to receptor (motor end plate in muscle cells)
- Action potential generated (in muscle)
- Action potential causes Ca2+ release
- Sliding filaments (contraction)
- Generation of muscle tension
The nervous system is like the ___________________
command center of the body
The nervous system (FUNC)
senses changes inside and outside of the body processes the
information, and responds by sending out commands.
Signal transduction within one neuron: (2x)
- action potential/electric impulses
- ion channels
Signal jumping from one neuron to another neuron: (3x)
- Synapse
- Neurotransmitters (released from presynaptic terminal)
- Receptors (on postsynaptic terminal)
Animal cells are surrounded by a
lipid bilayer membrane with proteins embedded.
The lipid bilayer membrane serves
as both an insulator and a diffusion barrier to ions.
The difference in the number of charged ions inside and outside of the cell RESULTS IN
different electric potential - membrane potential (A.K.A. transmembrane potential or membrane voltage)
The membrane is what?
impermeable, which means some molecules can get through while others can not
Is the voltage inside and outside the membrane always different?
Yes
The voltage inside is
ALWAYS Negative
In A&P, Polarized always means
negatively polarized
The concentration gradients of the ions RESULTS IN
electrochemical gradient → flow of ions down their concentration gradients when ion channels open
Ion channels allow what to happen when open?
allow certain chemicals get through when open
Ion channels open when?
they open and close either spontaneously or in response to a specific stimulus, such as the binding of a small molecule to the channel protein (ligand-gated ion channels) or a change in voltage across the membrane that is sensed by charged segments of the channel protein
For anything to happen _______ has to occur
Depolarization
For things to stay stable, __________________ has to continue
Polarization
Action potential occurs when
The membrane depolarizes
An action potential:
a rapid rise and subsequent fall in membrane potential (voltage)
across a neuron cell membrane with a characteristic pattern.
An action potential (nerve impulse) travels down
an axon, away from the cell body.
Neuromuscular Junction
Communication between a neuron and another cell occurs at a synapse. When the other cell is a skeletal muscle fiber, the synapse is known as a neuromuscular junction (NMJ).
Neuromuscular Junction is made up of
an axon terminal of a neuron, a specialized region of the sarcolemma called the motor end plate, and, in between, a narrow space called the synaptic cleft.
A motor neuron stimulates a muscle fiber through a series of steps. (3x) which are?
(1) The axon terminal of a neuron releases a chemical signal called neurotransmitter into the synaptic cleft. This signal is acetylcholine, or ACh.
(2) ACh binds to an ACh receptor on the motor end plate of the muscle fiber. The ACh receptor is a Na+ channel. ACh binding opens the channel, allowing Na+ to enter the cell.
(3) The inflow of positive charges (Na+) depolarizes the motor end plate and generates an action potential that sweeps across the sarcolemma.
Steps that Initiate a Muscle Contraction
- ACh released
- Action potential teachers T tubule
- Sacroplasmic reticulum releases stored Calcium
- Active sites exposed and cross-bridges form
Contraction cycle begins
Steps that End a Muscle Contraction
- ACh is broken down
- Sacroplasmic reticulum reabsorbs Calcium
- Active sites covered, and cross-bridge formation ends
- Contraction ends
- Muscle relaxation occurs
The only energy source used directly for muscle contraction is
ATP
Available energy stores are depleted within
4-6 seconds in active muscles.
Cardiac muscle cells are found only in
the heart
Cardiac muscle cells are relatively ____________ compared to skeletal muscle cells.
small
A typical cardiac muscle cell has
a single, centrally placed nucleus.
Cardiac muscle cells are typically
branched.
Each cardiac muscle cell contacts
several others at specialized sites known as intercalated discs.
Cardiac muscle tissue contracts without
neural stimulation.
The nervous system can alter the pace or rate set by ___________ and adjust the amount of tension produced during a contraction (CARDIAC)
the pacemaker cells
Smooth muscle do not have ___________
straition
Smooth muscles tissue (DESC)
Forms sheets, bundles, or sheaths around other tissues in almost every organ –> function to move substances through internal passageways
Smooth Muscles tissue (func)
to move substances through internal passageways.
Smooth muscles play a variety of roles in various body systems: (4x)
1) Cardiovascular System
2) Respiratory System
3) Digestive System
4) Urinary System
Cardiovascular System (Smooth muscle) Where are they and what do they do?
Smooth muscles around blood vessels control blood flow through vital organs and help regulate blood pressure.
Respiratory System (Smooth muscle)
smooth muscles contract or relax to alter the diameters of airway and change their resistance to airflow.
Digestive System (Smooth muscle)
contraction of smooth muscle in the walls of the GI tract moves materials along the tract; in the walls of the gallbladder ejects bile into the GI tract.
Urinary System (Smooth muscle)
contraction of smooth muscle in the walls of the ureters transports urine to the urinary bladder, and in the wall of the urinary bladder forces urine out of the body.
Where are sphincters located?
In both the digestive and urinary systems
sphincters (func)
control the movement of materials along internal passageways.
Smooth muscle tissue, like skeletal and cardiac muscle tissues, contains
actin and myosin
Each smooth muscle cell is ________ shaped, and has _____________
spindle-shaped (tapered at both ends) and has a single, centrally located nucleus.
Smooth muscle cells lack
myofibrils and sarcomeres.
Because Smooth muscle cells lack myofibrils and
sarcomeres, this tissue
has no striations and is called nonstriated muscle.
Muscle fibers in a skeletal muscle form bundles called
fascicles
The muscle fibers in a single fascicle are
parallel,
the arrangement of fascicles in skeletal muscles
can vary as parallel muscles, convergent muscles, pennate muscles, and circular muscles
The human body has approximately
700 muscles.
The skeletal system is divided into
axial and appendicular divisions
The axial muscles arise on the axial skeleton, including what %
60% of the skeletal muscles.
The axial muscles located at
(1) position the head and vertebral column, (2) move the rib cage, assists the movements required for breathing, (3) form the pelvic floor.
The appendicular muscles
stabilize and move the appendicular skeleton, 40% of skeletal muscles,
The appendicular muscles are located at
the pectoral (shoulder) and pelvic girdles and the upper and lower limbs.
These are superficial muscles, which tend to be
rather large.
The superficial muscles cover
deeper, smaller muscles that we normally cannot see unless the overlying muscles are removed.
