Study Guide: Chapter 10 The Muscular System
What is titin?
Structual protein that connects the Z discs to the M line of the sarcomere, stabilizing the position of the thick filament. Gives the elasticity and extensibility of myofibrils.
Regulatory proteins
Switch contraction process on/off
Neuromuscular junction
Synapse between motor neuron and individual muscle fiber
The Connective tissue covering collectively become one forming a __________ to tie unto _________.
TOGETHER-->TENDONS-->ORIGIN and INSERTION
The myosin ____ points towards the M line in the center of the sarcomere
Tail
Muscle belly connects to the ___ which connects to the ____.
Tendon, Bones
Tonic
Tension
Isometric Contraction
Tension generated is not enough to exceed the resistance of the object to be moved Energy is still spent yet no body movement Hold your anatomy text while maintaining your arm and forearm stretched out. Stabilizes joints as others are moved
Extensibility: What is it?
The ability of muscular tissue to stretch within limits without being damaged.
I band
The lighter, less dense area that contains the rest of the thin filaments but no thick filaments. Z disc passes through the center of each I band
This is what makes your muscle so strong. at its junction with the bone, the surface tissue of the tendon is continuous with the _________ while its deeper collagen fibers enter the one to blend with collagen of the _____ ______ ______.
This is what makes your muscle so strong. at its junction with the bone, the surface tissue of the tendon is continuous with the (PERIOSTEUM) while its deeper collagen fibers enter the one to blend with collagen of the (osseous extracellular matrix.)
What type of connective tissues are tendons?
Tough, glistening, white Dense regular connective tissues
What are the qualities of tendons?
Tough, glistening, white. Not very vascularized (little blood vessels), lack muscle cells, and composed mainly of parallel arrangements of collagen protein fibers.
Contractility: What is it?
Upon stimulation via Action Potential contraction occurs which generates tension / force of contraction pulls on attachment points
Skeletal muscle tissue: Voluntary or involuntary?
Voluntary: actions can be consciously controlled with the somatic nervous system
Smooth muscle tissue: Location
Walls of the hollow interal structures like blood vessels, airways, and most organs in the abdominopelvic cavity. Hair follicles in the skin.
____ thin filaments for every _____ thick filaments are in the region of filament overlap
2 thin filaments for every 1 thick filament
How many myosin make up a thick filament?
300 Myosin make up a thick filament.
H zone
A narrow region in the center of each A band that contains thick filaments but no thin filaments
M line
A region in the center of H zone that contains proteins tha thod the thick filaments together at the center of the sarcomere
Synaptic vesicles contain...
ACh =Acetylcholine (neurotransmitter)
Producing heat - As ______ tissue contracts, it produces heat through _________ . Heat is released to maintain normal body __________. ONE METHOD IS...
As (MUSCULAR) tissue contracts, it produces heat through (THERMOGENESIS). Heat is released to maintain normal body (TEMPERATURE) . (SHIVERING)
Endomysium: Binds _____ ______ together yet loose enough to move freely
Binds MUSCLE FIBERS together yet loose enough to move freely
What do myosin heads bind during contraction?
Binds to myosin binding sites on thin filaments during contraction
What are the function of capillaries?
Bring oxygen and nutrients to muscle fibers. Remove heat and waste products of muscle metabolism.
What surrounds muscle fibers and whole muscles, and carry the blood vessels and nerves that exert their effects on individual fibers?
CONNECTIVE TISSUE
Stores/moves substances within the body: Cardiac muscle contraction _______ blood through the body's blood ________
Cardiac muscle contraction (PUMPS) blood through the body's blood (VESSELS)
Smooth muscle tissue: Unique Characteristics
Connective tissue components: Endomysium Contractile proteins NOT organized into sarcomeres very little sarcoplasmic reticulum Transverse tubules NOT present Contain gap junctions in visceral smooth muscle; none in multiunit smooth muscle Autorhythmicity in visceral smooth muscle Source of Ca2+ for contraction: Sarcoplasmic Reticulum and interstitial fluid Considerable regeneration via pericytes compared to other muscle tissues
Cardiac muscle tissue: Unique Characteristics
Connective tissue components: Endomysium, perimysium Contractile proteins organized into sarcomeres SOME sarcoplasmic reticulum Transverse tubules present aligned with each Z disc Intercalated discs contain gap junction and desmosomes Autorhythmicity (beats to own rhythm) Source of Ca2+ for contraction: Sarcoplasmic Reticulum and interstitial fluid Limited regeneration
Skeletal muscle tissue: Unique Characteristics
Connective tissue components: Endomysium, perimysium, epimysium Contractile proteins organized into sarcomeres Abundant sarcoplasmic reticulum Transverse tubules present aligned with each A-I band junction no Junctions between fibers No Autorhythmicity Source of Ca2+ for contraction: Sarcoplasmic Reticulum
Extensibility: What limits the range of muscle tissue?
Connective tissue limits range. keeps it within contractile range.
What are the components of myosin?
Contains a tail and two myosin heads
Myofibrils
Contractile fibers that looks striped (striated)
Epimysium: Wraps all _____ TOGETHER forming the _____ _____
Wraps all FASCICLES together forming the MUSCLE BELLY
Cardiac muscle tissue: Striations?
Yes
Skeletal muscle tissue: Striations?
Yes, because of alternating light and dark protein bands are visible when looking in microscope
Extensibility: Does cardiac muscle stretch?
Yes, every time your heart fills with blood
During muscle contraction, what happens to the z discs during the sliding filament mechanism?
Z discs come closer together
Sarcoplasm
Cytoplasm of a muscle fiber
A band
Dark middle part of the sarcomere that extends the entire length of the thick filaments and the part of the thin filaments that overlap with the thick filaments
Around the periphery of the muscle is a thicker covering of ____ ____ connective tissue called the ________ that binds all the ______ together to form the muscle belly.
Dense Irregular, Epimysium, Fascicles
Terminal Cisterns
Dilated sacs of the sarcoplasmic reticulum that butt up against T tubules. When triggered Ca2+ will be released from the terminal cisterns into the sarcoplasms triggering muscle contraction
Hypertrophy
Dramatic muscle growth occuring after birth. Enlargement of muscle fibers. Increased production of myofibrils, mitochondria, SR, and organelle
Each skeletal muscle is a separate _____ composed of hundreds to thousands of skeletal muscle cells, also called ______ _____ because of their _______ shape
Each skeletal muscle is a separate (ORGAN) composed of hundreds to thousands of skeletal muscle cells, also called (MUSCLE FIBERS) because of their (ELONGATED) shape
Electrical excitability: To main types of stimuli trigger action potentials in muscle cells:
Electrical and chemical stimuli
Where do nerves typically enter the muscle?
Enters via stable tendon (origin)
Fascia
Epimysium, Perimysium, Endomysium
Iso
Equal
Groups of muscle fibers form bundles called _____ and it is covered by a ______ ______ connective tissue covering called the _______________
Fascicle, Dense Irregular, Perimysium
Smooth muscle tissue: Cells
Fiber is thickets in the middle and tapered at each end. Has one centrally positioned nucleus. Not striated.
Perimysium allows freedom of motion between each ______
Freedom of motion between each FASCICLE
During embryonic development, where do muscle fibers arise?
From the fusion of a hundred small mesodermal cells called myoblasts.hence, why each fiber is a single cell with a hundred or more nuclei.
Necrotizing fasciitis
HOMEOSTATIC IMBALANCE. Caused by Streptococcus pyogenes (anaerobic bacteria)
Myosin heads
Head projects outward from the shaft in a spiral ing fashion each extending toward one of the six thin filaments that surround the thick filament.
Cardiac muscle tissue: Function(s)
Heart Contraction responsible for blood circulation
Cardiac muscle tissue: Location
Heart where it forms the heart walls
Triad
1 T tubule and 2 terminal cisterns
What can adjust HR by speeding up or slowing down pacemaker
Hormones and neurotransmitters
What hormones promote muscle enlargement?
Human Growth Hormone and Testosterone
The contraction Cycle
1. ATP hydrolysis 2. Attachment of Myosin to actin forming cross-bridges 3. Power stroke 4. Detachment of myosin from actin
Motor Protein
a protein that convert ATP chemical energy into the mechanical energy of motion to produce force
Electrical excitability: Where do chemical signals arise? Example.
a stimuli released by chemicals to stimulate an action potential. Neurotransmitter released by neurons. hormones distributed by blood. Changes in pH.
Glycogen
a storage molecule containing a lot of linked glucose molecule. For use when a muscle needs energy and all glucose has already been used... it uses glycogen
Muscle action potentials travel...
along the sarcolemma and through the transverse tubules, quickly spreading throughout the muscle fiber
Myofibrils are built from 3 types of proteins. What type are they?
1. Contractile Proteins 2. Regulatory proteins 3. Structural Proteins
The prime function of muscle is...
changing chemical energy into mechanical energy to perform work
Muscular tissues have 4 special properties that enable it to perform its functions and contribute to the homeostasis of your body: these are...
1. Electrical excitability 2. Contractility 3. Extensibility 4. Elasticity
5 Functions of muscular tissue:
1. Producing Body Movements 2. Stabilizes Body Positioning 3. Stores/moves substances within the body 4. Heat Production 5. Facial Expressions
During muscle contraction, what happens to the length of the individual thick and thin filaments?
do not change
Sarcoplasmic Reticulum
fluid filled system of membranous sacs like the smooth ER that encircles each myofibril. In a relaxed muscle fiber the SR stores Ca2+
Sarcomere
functional unit of muscle—contractile unit
Contractile Proteins
generate force during contraction
Hyperplasia
Increase in the number of fibers
What does actin look like?
Individual actin molecules that join together to form an actin filament that is twisted into a helix
Cardiac muscle tissue: Voluntary or involuntary?
Involuntary (Autonomic Nervous System) - contraction and relaxation can not be controlled
What can we attribute to the reddish appearance of skeletal muscles?
It contains a large population of highly vascularized muscles cells in the muscle belly
Skeletal muscle tissue: Cells
Long, cylindrical fiber with many peripherally located nuclei. Unbranched. Striated. Limited capacity for regeneration via satellite cells.
Myosin
Main component of thick filaments and functions as the motor protein of all 3 types of muscle.
Metro
Measure or length
What are Capillaries?
Microscopic blood vessels in muscle tissue. Each muscle fiber is in close contact with one or more of them.
because hypertrophied muscles contain more myofibrils, they in turn have what quality?
More forceful contractions
Skeletal muscle tissue: Location
Most commonly attached by tendons to bones
The ___ fibers initiate the contractile function of muscle cells while the ___ fibers provide a feedback to the nervous system to regulate motor function.
Motor Fibers Sensory Fibers
Structure of a skeletal muscle: A skeletal muscle consists of a ______ _______ connected by ________ to the _________.
Muscle Belly (body), Tendon, Skeleton
Excitation—Contraction Coupling
Muscle action potential propagates along sarcolemma and into the T tubules causes Ca2+ release channels to open Ca2+ flows out of Sarcoplasmic reticuli [Ca2+] HIGH
Once fusion occurs, what happens?
Muscle fibers can't undergo cell division.
The most important components of a skeletal muscle are the
Muscle fibers themselves.
Duchenne's Muscular Dystrophy—Inherited via an X-linked recessive gene
Mutated gene coding for dystrophin—little or none • Sarcolemma tears • Damages plasma membrane / cell die ii. Children in wheelchair by ~12—mostly boys iii. Muscle fibers do not contract therefore they atrophy
On each actin molecule is a ________ _______ ________ where a myosin head can attach.
Myosin Binding Site
Thick fibers are made of
Myosin Filaments
What are the 2 contractile proteins in muscle?
Myosin and Actin
Structural proteins
keep thick/thin filaments in proper alignment, provide elasticity and extensibility to myofibrils, link myofibrils to sarcolemma
What does myosin look like?
looks like 2 golf clubs twisted together.
What does the sarcoplasm contain?
lots of glycogen and myoglobin.
Z discs
narrow plate shaped region of dense protein material that separate one sarcomere from the next.
During muscle contraction, what happens to myosin heads during the sliding filament mechanism?
Myosin heads pull the thin filaments towards the M line
Z discs
Name Number 1
I band
Name Number 2
Thin filament (actin)
Name Number 3
Thick Filament (Myosin)
Name Number 4
M line
Name Number 5
A band
Name Number 6
H zone
Name Number 7
Z discs
Name the component of the sarcomere
Muscle action potentials arise at the..
Neruromuscular Junction
What do the nerves typically enter the muscle as?
Neurovascular bundle (nerve, an artery and one or two veins)
Smooth muscle tissue: named after its unique physical characteristic = Striations? Voluntary or involuntary?
Nonstriated and involuntary (autonomic nervous system)
Multiple ____ are beneath the Sarcolemma
Nuclei
What are all the muscle proteins that are in a sarcomere?
p) Thin=Actin filaments q) Thick=Myosin filaments s) Myosin heads t) Troponin u) Tropomyosin v) Titin
Synapse
region where communication occurs between 2 neurons or a neuron and a target cell.
Describe the nerves in most skeletal muscles such as limbs and the head.
One main nerve that carries motor neurons to the muscle and sensory neurons away from the muscle
Fibrosis
replacement of muscle fibers by fibrous scar tissue limiting the regeneration of skeletal muscle tissue
Since the cells don't physically touch, the action potential can not jump. How does the first cell communicate with the second cell?
Releasing a chemical messenger called neurotransmitter
Surrounding each muscle fiber is thin wrapping of ________ _______ called the _____________
Reticular Fibers, Endomysium
Elasticity is the ability of muscles to do what?
Return to the original length and shape after contraction or extension.
How are the different ways a TENDON can look?
Ropelike, short, or in Flat sheets called APONEUROSIS
What structure releases calcium ions to trigger muscle contraction?
Sarcoplasmic Reticulum
A few myoblasts due persist in mature skeletal muscle as....
Satellite cells
Shortening of the ________ causes shortening of the whole ________ ______ which in turn leads to shortening of the entire _______.
Shortening of the SARCOMERES causes shortening of the whole MUSCLE FIBER which in turn leads to shortening of the entire MUSCLE.
Stores/moves substances within the body: Skeletal muscle move ________ through the body and return ______ from _________ to the heart
Skeletal muscle move (LYMPH) through the body and return (BLOOD) from (VEINS) to the heart
What are the 3 types of muscular tissue?
Skeletal muscle tissue Cardiac muscle tissue Smooth muscle tissue
Filaments or myofilaments
small protein structures within myofibrils
Stores/moves substances within the body: Smooth muscle contraction of _______________ can prevent the outflow of contents in _____________ ______________ LIKE...
Smooth muscle contraction of (SPHINCTERS) can prevent the outflow of contents in (HOLLOW ORGANS). (HOLDING IN PEE OR PROPELLING URINE)
Extensibility: What muscle type stretches the most?
Smooth muscle stretches the most. stomach filling with food
Name the two cells making up the Neuromuscular Junction
Somatic Motor Neuron Muscle Fiber
Nerves stimulating skeletal muscle fibers are known as
Somatic Motor Neurons
Neurons that stimulate skeletal muscle fibers to contract are called...
Somatic Motor Neurons
Where do nerves typically spread to after entering?
Spreads through connective tissue. Spread through the muscle via the connective tissue channels formed by perimysium and endomysium as they wrap the muscle cells.
Stabilizes Body Positioning. Muscular tissue stabilizes _____ to maintain in a body position like....
Stabilizes (JOINTS) to maintain in a body position like keeping your head up
Synaptic cleft
space between two synapses that separate the two cells
What is the purpose of endomysium?
surrounds bind muscle fibers together, but loose enough to allow them to move freely over one another. carries blood vessels that supply the fibers with nutrients.
Sarcolemma (sarc=flesh; -lemma=sheath)
the plasma membrane of the muscle fiber, surrounds its sarcoplasm
Transverse Tubules
tiny invaginations of the sarcolemma that tunnel from the surface to the center of the muscle fiber (filled with interstitial fluid)
Skeletal muscle tissue: Named after its function which is:
to move the bones of the skeleton
______ muscle is found in walls of blood vessels
(SMOOTH) muscle is found in walls of blood vessels
Somatic Motor Neurons have a threadlike extension called a ________ which travels from the neuron _____ _____ in the ______ or _____ _____ to a group of skeletal muscle fibers in a muscle of the body
AXON CELL BODY Brain or Spinal Cord
What is the main component of thin filaments?
Actin
Thin fibers are made of:
Actin filaments
Thin filaments contain what 3 proteins?
Actin, troponin, and tropomyosin
Electrical excitability: both muscle and ____ cells respond to stimuli by producing electrical signals called ______ _______
Action potentials (impulses) MUSCLE ACTION POTENTIALS
During muscle contraction, what happens to the sarcomere during the sliding filament mechanism?
Sarcomere Shortens
What do tendons do?
Attach muscle belly to bone
Autorhythmicity of smooth muscle is due to:
Autonomic division of the nervous system Hormones
Electrical excitability: Where do electrical signals arise? Example.
Autorhythmic electrical signals arise in the muscular tissue itself. Like the heart's pacemaker.
Tails of neighboring myosin molecules lie ____ to one another, forming the shaft of the _____ filament
Parallel. THICK.
Motor endplate
Part of sarcolemma Highly folded area increases ______________ __________ Multiple ACh receptors—What are these receptors?
Electrical excitability: Action potentials travel along a cell's _____ ______ due to the presence of ______ ______
Plasma Membrane Ion Channels
Smooth muscle tissue: Function(s)
Propel food through the GI tract, contractions during birth
Myogloblin
Protein found only in muscle that binds O2 molecules that diffuse into muscle fibers from interstitial fluid. Releases O2 to mitochondia for ATP production.
Sheet like muscles of the body wall have what type of nerves?
Receive multiple nerves that make it possible to independently control different segmental levels within the muscle sheet
Tropomyosin
Regulatory Protein. A part of thin filament. When a skeletal muscle fiber is relaxed, tropomyosin covers the myosin binding site, preventing myosin from binding to actin
Troponin
Regulatory Protein. A part of thin filament. When calcium ions bind to troponin, it undergoes a change in shape which moves tropomyosin away from myosin binding sites. Muscle contraction begins as myosin binds to actin.
Troponin and Tropomyosin are what type of proteins?
Regulatory Proteins