Muscular System Part 1 Flashcards
There are estimated over _____ muscles particularly the skeletal muscles in the body.
650
Alternating light and dark bands (striations) as seen when examined with a microscope.
Skeletal Muscle Tissue
Skeletal muscle is referred to as the
striated muscle
Skeletal muscle tissue works mainly in what manner?
voluntary manner
Skeletal muscles are attached to the bones via
the ____
tendons
Type of muscle tissue that is found only in the walls of the heart
Cardiac Muscle Tissue
Cardiac Muscle Tissue is also referred to as the
myocardium
What is a pericardium?
It is a protective sac that surrounds the heart
Myocardium is located within the inner
lining of the heart which is the ____?
endocardium
Is Cardiac Muscle Tissue Non-striated or Striated?
Striated
Movement or action of the cardiac muscle tissue
involuntary
It is located in the walls of hollow internal
structures.
Smooth Muscle Tissue
Movement or action of the smooth muscle tissue
Usually involuntary
Four human body systems where smooth muscle tissues can be found
digestive system, respiratory system, renal system, and reproductive system
This is what the cell of the smooth muscle tissue contains that can connect to the neighboring cells which form in nest like network in which allow the cell to contract uniformly
filaments
Functions of Muscular Tissue
Producing Body Movements, Stabilizing Body Positions, Moving Substances Within the Body, Generating heat
A property of muscular tissue that pertains to the ability to respond to stimuli
Excitability
A property of muscular tissue that pertains to the ability to contract forcefully when stimulated
Contractility
A property of muscular tissue that pertains to the ability to stretch without being damaged
Extensibility
A property of muscular tissue that pertains to the ability to return to an original length.
Elasticity
It is a connective tissue component that is a dense sheet or broad band of irregular connective tissue that surrounds bundles of muscles fibers.
Fascia/Fascicle
It is a connective tissue component that is the outermost layer, which Separates 10-100 muscle fibers into bundles called fascicles.
Epimysium
It is a connective tissue component that encircles also a group of muscle fibers
that form a fascicle
Perimysium
Separates individual muscle fibers from
one another
Endomysium
This refers to the cord that attaches a muscle to a bone.
Tendon
It is a flattened tendon-like material that is broad in appearance
Aponeurosis
Neurons that stimulate skeletal muscle to contract.
Somatic Motor Neurons
Somatic Motor Neurons originates in the ____
central nervous system
The skeletal muscles make up between _____ of the total body weight
40% - 50%
The skeletal muscle mass begins to _____ as we grow older, typically begins at the age of ____
decline, 40
Muscles is made up of about
79% water
is the enlargement of existing muscle fibers.
Hypertrophy
the decrease in muscle strength due to the decrease in muscle mass.
atrophy
Two hormones that stimulates hypertrophy
Testosterone and growth hormone
These retain the capacity to regenerate
damaged muscle fibers.
Satellite cells
Refers to the formation of new muscle cells
Hyperplasia
The plasma membrane of a muscle cell is called ____
Sarcolemma
Tunnel in from the plasma membrane. Muscle action potentials travel through this.
Transverse (T tubules)
This is where calcium and ions that is needed for muscle contraction are being released.
Sarcoplasm
The cytoplasm of a muscle fiber.
Sarcoplasm
It is the stored form of glucose that the sarcoplasm contains and is used for
synthesis of ATP
glycogen
A red-colored protein that the sarcoplasm contains
myoglobin
Two components needed to bind oxygen molecules
glycogen and myoglobin
This releases oxygen when it is needed for ATP production.
Myoglobin
Thread like structures which have a contractile function.
Myofibrils
It is the basic unit of myofibrils.
Sarcomere
In order to contract, the muscle must be
stimulated by a nerve ending. It has to
propagate an _______ along the _____. Once there is an _____ there will be
an increased intercellular reaction that’s
why ____ also increases.
electrical current or action potential, sarcolemma, action potential, calcium level
Membranous sacs which encircle each myofibril.
Sarcoplasmic Reticulum (SR)
Sarcoplasmic Reticulum stores ___
calcium ions
Release of calcium ions triggers ____
muscle contraction
the final trigger for muscle contraction.
calcium ions (Ca++)
Low level of calcium in the body.
Hypocalcemia
There is too much calcium ions in the sarcoplasmic reticulum
Hypercalcemia
Function in the contractile process
Filaments
How many thin filaments are there for every thick filament
two thin filaments
Compartments of arranged filaments Basic functional unit of a myofibril.
Sarcomeres
Separate one sarcomere from the next
Z discs
Darker middle part of the sarcomere
A band
Lighter, contains thin filaments but no thick filaments
I band
Center of each A band which contains thick but no thin filaments
H zone
Supporting proteins that hold the thick filaments together in the H zone
M line
Myofibrils are built from three kinds of proteins. What are these muscle proteins?
Contractile proteins, Regulatory proteins, Structural Proteins
These generate force during contraction
Contractile proteins
These switch the contraction process on and off
Regulatory proteins
These align the thick and thin filaments properly in the myofibrils
Structural Proteins
These two contractile proteins are important for the generation of movement when there is an action potential or signal from the nervous system.
Myosin and actin
Functions as a motor protein which can achieve motion during contraction.
Myosin (Thick filaments)
Allows muscle contraction to begin as the myosin binds to actin.
Actin (Thin filaments)
Convert ATP to energy of motion.
Myosin (Thick filaments)
____ molecules provide a site where a myosin head can attach.
Actin (Thin filaments)
These two proteins are also part of the thin filament.
Tropomyosin and troponin
Can myosin bind to the actin? Why?
No, it is blocked from binding to actin.
A structural protein that stabilizes the position of myosin and accounts for much of the elasticity and extensibility of myofibrils
Titin
Structural proteins that helps align Actin (thin filaments)
Nebulin
A structural protein that links thin filaments to the sarcolemma
Dystrophin
Explain the Sliding Filament Mechanism
➢ Myosin heads attach to and “walk” along the
thin filaments at both ends of a sarcomere
➢ Progressively pulling the thin filaments toward
the center of the sarcomere
➢ Z discs come closer together and the sarcomere
shortens
➢ Leading to shortening of the entire muscle
Explain the contraction cycle
➢ The onset of contraction begins with the
sarcoplasmic reticulum releasing calcium ions
into the muscle cell
➢ Where they bind to actin opening the myosin
binding sites
4 main steps of contraction cycle
ATP hydrolysis, Formation of cross-bridges, Power stroke, Detachment of myosin from actin
Action potentials arise at the interface of the motor neuron and muscle fiber.
Neuromuscular junction
Where communication occurs between somatic motor neuron and a muscle fiber.
Synapse
Gap that separates the two cells.
Synaptic cleft
Chemical released by the initial cell communicating with the second cell.
Neurotransmitter (acetylcholine)
Sacs suspended within the synaptic end bulb
containing molecules of the neurotransmitter
acetylcholine (Ach).
Synaptic vesicles
The region of the muscle cell membrane opposite the synaptic end bulbs
Motor end plate
It is an enzyme that breaks down the ACh which terminates its activity
acetylcholinesterase (AChE)
One of the most poisonous biological substances known
Botulinum Toxin
Botulinum Toxin is a neurotoxin that is
produced by the bacteria known as the
clostridium botulinum
is a serious illness that can affect the nervous system
Botulism
Botulism occurs when a poisonous substance called the botulinum toxin reproduce ___
skeletal muscle paralysis
A plant poison used by South American Indians on arrows and blowgun darts.
Curare
Causes muscle paralysis by ______ inhibiting Na+ ion channels.
blocking ACh receptors
Derivatives of curare are used during surgery to __________
relax skeletal muscles
It is an inhibitor that interferes with the actions of acetylcholinesterase by slowing it down or removing it.
Anticholinesterase
is an autoimmune disorder of the muscles in which the antibodies of the body is getting destroyed.
Myasthenia gravis
It is the process of producing ATP in muscle fibers
Muscle Metabolism
This must be produced by the muscle fiber
ATP
three ways to produce ATP
• From creatine phosphate
• By anaerobic cellular respiration
• By aerobic cellular respiration
It is the molecule that can store energy in its
phosphate bond in where they store energy
Creatine Phosphate
The process of transferring a phosphate group to adenosine diphosphate yields what?
ATP
Creatine phosphate and ATP provide enough energy for contraction for about _____
15 seconds
This process occurs on the muscles during hard exercise
Anaerobic Respiration
Differentiate Anaerobic Respiration and Aerobic Respiration
Anaerobic Respiration does not require oxygen; Aerobic Respiration needs oxygen
_____ is used to generate ATP when the
supply of creatine phosphate is depleted
Glucose
Two sources where glucose can be obtained or found
from the blood and from glycogen stored in muscle fibers
The process of breaking down glucose into three molecules of carbon and yields 2 net ATP
Glycolysis
If sufficient oxygen is present, _______ formed by glycolysis enters ________
pyruvic acid / pyruvate; aerobic respiration
If oxygen levels are low, __________ convert _______ to ______
anaerobic reactions; pyruvic acid; lactic acid
If the lactic acid was not carried away by the blood, there is a possibility that the lactic acid
will cause ____
lactic acidosis
How long can Anaerobic respiration provide enough energy for any muscle activity
30 to 40 seconds
In the aerobic respiration, the pyruvate enters what organelle?
mitochondria
Two sources of oxygen and are referred as the oxygen binding proteins
Myoglobin and hemoglobin
Can be defined as the exercise induced decrease in the ability to produce force
Muscle Fatigue
The added oxygen that is taken into the body after exercise
Oxygen Debt
Consists of a motor neuron and the muscle fibers it stimulates.
Motor Units
The axon of a motor neuron branches out
forming __________ with different muscle fibers
neuromuscular junctions
Muscles that control voice production have _____ muscle fibers per motor unit
2 - 3
Muscles controlling eye movements have _____ muscle fibers per motor unit
10 - 20
Muscles in the arm and the leg have _______ muscle fibers per motor unit
2000 - 3000
The brief contraction of the muscle fibers in a
motor unit in response to an action potential
Twitch Contraction
The contraction can be generated with a single
axon potential which is known as the
muscle twitch
A brief delay between the stimulus and muscular contraction. The action potential sweeps over the sarcolemma and Ca++ is released from the SR.
Latent period (2 msec)
Ca++ binds to troponin. Myosin-binding sites on actin are exposed. Cross-bridges form.
Contraction period (10–100 msec)
Ca++ is transported into the SR. Myosin-binding sites are covered by tropomyosin. Myosin heads detach from actin.
Relaxation period (10–100 msec)
It is a period where the muscle fiber temporarily cannot respond to another action potential
Refractory period
Skeletal muscle has a refractory period of
5 milliseconds
Cardiac muscle has a refractory period of
300 milliseconds
A small amount of tension in the muscle due to weak contractions of motor units
Muscle Tone
The tension developed remains constant while the muscle changes its length
Isotonic contraction
Differentiate Concentric and Eccentric
• Concentric - muscle shortens
• Eccentric - muscle lengthens
The tension generated is not enough for the object to be moved and the muscle does not change its length
Isometric contraction
What is the cause if the pigmentation of Red muscle fibers
high myoglobin content
What is the cause of the light colored pigmentation of White muscle fibers
low content of myoglobin
Fibers that can utilize oxygen in order to generate energy for movement
Slow Oxidative Fibers (SO Fibers)
Slow Oxidative Fibers have a slow speed of contraction. Twitch contractions last from ___
100 to 200 msec
Intermediate in diameter between the other two types of fibers
Fast Oxidative–Glycolytic Fibers (FOG Fibers)
Twitch contractions of FOG Fibers last
less than 100 msec
These fibers store energy that can be used for
the short burst of movement and does not require oxygen to generate energy
Fast Glycolytic Fibers (FG fibers)
Through Aerobic exercise, some FG
fibers are transformed into _____
FOG fibers
When we exercise the tendons will become thicker or thinner?
thicker
During exercise, only 40% of the energy is released in the muscle activity. The remaining 60% will be given as ____
heat
