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72 Cards in this Set

  • Front
  • Back
MUSCLES
latin meaning
"mus' means little mouse
MUSCLES
TYPES
3 types
skeletal
smooth
cardiac
MUSCLES
GENERAL CHARACTERISTICS
Excitability/Irritability
Contractility
Extensibility
Elasticity
EXCITABILITY/IRRITABILITY
ability to recieve and respond to stimulus
-usually the result of a chemical message that results in an electrical signal
-followed by a series of biochemical reactions
CONTRACTILITY
Ability to contract or shorten when stimulated
EXTENSIBILITY
Ability to stretch
Example: heart muscle: Sterlings law
STERLINGS LAW
The more stretch the harder it will contract
ELASTICITY
ability to recoil after being stretched
example: springs, rubber band
GENERAL FUNCTIONS OF MUSCLE
Movement: skeletal, blood, food, venous, lymph, arteries & veins (can constrict & dilate)
Posture: resistance to gravity
Joint Stabilization:
Heat Generation: contraction (shivering)
Metabolic: Energy (Alanine Pathway through which ATP can be made)
MUSCLES
what are they?
what are they made up of?
what is in every muscle
An organ
made up of Fibers, Vessels, Nerves, & connective tissues.
-Each muscle has 1 nerve, 1 artery, several veins & numerous, wide, cros-linked capillaries
MUSCLE FIBERS
what is the smallest unit of muscle fibers?
Myofilaments
-long filament consisting of several types of contractile proteins
SARCOMERE
what is it
what is it considered to be
Bundle of myofilaments
considered the basic contractile unit
MYOFIBRIL
A column of sarcomeres arranged from end to end.
SARCOLEMMA
Another term for cell membrane
Covers myofibrils
NUCLEI
where lye?
just below sarcolemma
WHAT TYPES OF CELLS ARE MULTINUCLEATE
muscle cells
MITOCHONDRIA
where located?
dispersed throughout sarcomeres
ENDOMYSIUM
fine sheath of reticular connective tissue that surrounds each fiber
MUSCLE FIBER
is a nother term for?
muscle cell
PERIMYSIUM
Fibrous connective tissue that surround discrete bundles of muscle fibers
FASICLES
discrete bundles of muscle fibers surrounded by perimysium
EPIMYSIUM
A sheet of regular connective tissue that covers an individual muscle (which is made up of groupings of fasicles)
FASCIA
Sheets of connective tissue that separate muscles from one another.
MUSCLE CELLS (FIBERS)
describe them
where do they originate from?
what do they do?
what happends to their surface?
-Each cell is a long, cylindrical, multinucleate cell.
-Originate from embryonic mesoderm cells called myoblasts
-Several myoblasts fuse to form a multinucleate muscle cell
-Special receptors for the NTX Ach start to sprout over surface of myoblasts.
WHAT HAPPENDS WITH CONTINUING GROWTH?
Nerve cells eventually come in contac with the myoblasts
WHAT DO NERVE CELLS RELEASE?
Agrin, which stimulates an ordered clustering of the Ach receptors, forming the motor end plate.
SARCOPLASM
what is it?
what does it contain?
what does it have?
Cytoplasm of a muscle cell
Contains glycosomes,which stores glycogens
Contains myoglobin(similar to Hgb) acts as oxygen storage site
Has increased # of electrolytes & mitochondria
Has sarcoplasmic reticulum
SARCOPLASMIC RETICULUM
what is it
what is it similar to
Specialized structure that helps maintain calcium controls to prevent degradation of cells

Like ER
CONTRACTILE ELEMENTS
What are the types
What are they involved in?
How are they arranged?
Actin/Myosin: Interdigitated protein strands
Involved in contraction
Arranged into band like structures
MAJOR BANDS
name the types & describe them
what happends when myofibrilsare atarched?
I Bands: Isotropic - light difraction
Consists only of actin.
A Bands: Anisotropic - Myosin & ends of
Actin
Z Discs: Protein at end of each actin
molecule.
Attaching 1 myofibril to another = uniform contraction of multiple units.
MYOSIN
what is it made up of?
what is it?
What types of chains are there and what do they do?
made up of 6 polypeptide chains
Is an ATP Binding site.
2 Heavy Chains: wrap in a sprial fashion to form a double helix,ending in a globular head.
4 Light Chains: Help in forming head, function to control head movement during crossbridging.
ACTIN
what is it?
what is 1 unit called?
what does each actin contain?
what is each bound to?
how is F actin formed?
Globular polypeptide
1 unit is calle G actin
Each G actin contains an active site for binding myosin
Each G actin is bound to 1 molecule of ADP
Link long strings of G actin to form F actin.
TROPOMYOSIN
what type of shape?
where is it located?
What does it do at rest?
What does it prohibit?
Rod shaped protein
Wraps spirally around F actin strands
At rest: it covers active site of actin
Prohibits actin/myosin crossbridging
TROPONIN
what are the 4 forms?
what does each form do?
3 - polypeptide complex, loosely bound to each other.
TN I - Stronga affinity for actin. Plays inhibitory role.
TN T - Binds tropomyosin, helps position it onto actin.
TN C - Binds calcium ions
MUSCLE CONTRACTION
Requires special structures:
Sarcoplasmic Reticulum
T-Tubules
Motor End Plates
Each muscle is innervated by motor neurons, which originate from brain or spinal cord and terminate into NMJ
NMJ
Neuromuscular Junction
An invagination of the sarcolemma
SARCOPLASMIC RETICULUM
Smooth ER
stores calcium
T-TUBULES
Transverse tubule, a lumen contiguous with the sarcolemma that helps to transmit the impulse to all nearby muscle cells. Ensures that each impulse is transmitted simultaneously.
MOTOR END PLATE
what is it?
What is it covered by?
what is the synaptic cleft
What does it contain?
What is the terminal end of the nerve made of?
Invagination of the sarcolemma by the NMJ
Covered by Myelinating Schwann Cells
The synaptic cleft is a 1-2 nm space between the nerve & the muscle
Contains ECF
Terminal end of the nerve: Acetylcholine
SYNAPSE
what does the terminal end of the nerve contain?
Terminal end of nerve contains machinery for Acetylcholine Manufacture
ACETYLCHOLINE
what is it stored as?
what does it attach to and how?
Stored as vesicles, attached to cytoskeleton by binding proteins.
SARCOLEMMA
where is it?
what is it rich in?
what do ion channels do?
how do you create an open channel?
what does it store
On other side of muscle cell
Rich in Ach receptors
Ion channels that allow for the influx of Na+ ions
2 molecules bind together to the receptor = open channel
Stores acetylcholinesterase
ACETYCHOLINESTERASE
An enzyme that breaks down Ach
ACTION POTENTIALS
what type of ion composition?
Slightly leaky to?
what is it composed of?
what causes channels to open/close?
what type of gradiants does it have?
Intracellular ion composition
Slightly leaky to K+
Composition includes variety of channels & receptors
Channels can open/close due to a variety of stimuli
Gradiants (has both chemical & electrical)
-inside cell: high K, low Na
-outside cell: high Na, low K
ACTION POTENTIALS (Cont'd)
RMP?
What does the action potential do & how?
What types of channels are there & what do they do?
RMP: -90 mV
Action potential: Activity(stimulates cell so that it will contract)
Na, K, & Ca channels (allow for action potential. opening & closing of these at diff times triggers activity)
CONTRACTION
expl the steps
1. AP > opens Na channels > AP
2. Voltage-gated Ca channels
3. Exocytosis of Ach
4. Ach > Ach Receptor > Na Channels
5. Voltage gated Ca channels
6. Sarcoplasmic reticulum
CONTRACTION CONT'd
expl steps.
7. Ca++ influx: binds to the C subtype of troponin.
8. This allows for conformational change in Troponin.
9. movement of troponin pushes tropmomyosin out of way
10. exposes active site actin, & allows for actin-myosin crossbridging.
CONTRACTION
what is attached to myosin head?
what happends when actin binding site is exposed?
what is the result?
what does this change?
Myosin head has ADP & Pi attached to it,
this is the ready position
When actin binding site is exposed, myos
in attach to it
As a result it releases ATP
Changes energy of molecule & shifts pos.
to an angle of 70 degrees
CONTRACTION CONT'D
what is the shift called?
what does it do, in essense?
what are a lg quantty of these working strokes?
-the angle of shift is called working stroke
-it in essence, moves the actin molecule
-large quantity of these working strokes is muscular contraction
CONTRACTION CONT'D
what happends after the working stroke
where is ATP generated from?
what does happens to the ATP & Myosin?
-After the workin stroke, ATP attaches to myosin head, and creates energy to release it from actin.
-ATP is generated from ADP & Pi.
-ATP is then hydrolyzed, & mysosin goes back to ready position.
MUSCLE METABOLISM
what are the mechanisms that do this?
what does it depend on?
several mechanisms:
1. Aerobic
2. Anaerobic
3. Creatine Phosphate
4. Glucose
depends on energy availability & oxygen available to cell
AEROBIC (MUSCLE METABOLISM)
what does this allow for?
what does it require
how is ATP made? how many steps involved?
-When sitting
-Allow for glycolysis, Krebs cycle, & electron transport
- Requires 02, glucose, mult enzymes, & cofactors
- Takes glucose & converts it to ATP through a multiple step process.
ANAEROBIC (MUSCLE METABOLISM)
when does this occur
what does it require
what is glucose converted to?
what happens then?
-Occurs when O2 availability is limited
-Uses glucose OR glycogen
-Converts glycose to pyruvate, which is then converted to lacate & H+ ions (LDH)
-Lacate can enter bloodstream for conversion by liver to glycogen.
ANAEROBIC VS AEROBIC
which one is more efficient
which one is faster
which one produces a disfunctional enzyme?
Anaerobic - much less efficient @ converting glucose ATP.
Anaerobic - much faster (x2)
Production of H+ ions in anaerobic produces localized acidosis which is an enzyme disfunction.
CREATINE PHOSPHATE
what does it contain
what can it produce & how
formula
CP is unique to muscles, contains high energy phosphate bonds
Can be coupled with ADP to produce ATP
ADP + CP = ATP + creatine (CK)
This is one way ATP is replenished
GLUCOSE (MUSCLE METABOLISM)
what is it
what does it do to make energy
Glucose is an alanine pathway
Converts Alanine to Pyrovate via Alanine Aminotransferase
Pyruvate converted to glycogen (which can be used as energy
MUSCLE USE
At rest, what are you using?
When is ATP stored?
When is CP used?
During strenous acitivity, what are you using?
What happens to ATP during strenous activity?
At rest: aerobic
ATP: stored in 4-6 seconds
Immediately utilizes CP: 10-15 sec
Strenuous Activity longer than a min: Anaerobic.
Anaerobic - ongoing exercise: as long as oxygen is available, more ATP will be regenerated
MUSCLE FATIGUE
Why does this happen?
Then what happens to the muscles?
What is Rigormortis?
The muscle still recieves signal, but
lacks ATP to work.
Additionally, accumulation of H+ decr
eases the efficiency of required enzy
mes
Rigormortis: NO ATP: unable to relea
se from actin. Muscles stay contract
ed.
RESPIRATORY ACIDOSIS
When you have trouble breathing. Then you produce more lactic acid than the body can process.
SMOOTH MUSCLE
where found?
how are they diff from skeletal?
Functions?
Found in hollow organs
Differences:
Spindle shaped, 1 nucleus, usually
arranged in 2 sheets, lacks NMJ
associated with skeletal muscle,
innervated by the ANS, shorter than
skeletal.
Functions: moves blood/food/small
molecules, dilation & constriction,
responds to signals other than Ach
ANS:
what do the abbreviations stand for?
what does it work like?
Autonomic nervous system
works automatically to tell your heart to beat etc.
NMJ:
what does it stand for?
Neuromuscular Junction
SMOOTH MUSCLE
what doe ANS nerves have?
What do vercosities release?
What are 2 things it does not contain?
What does sarcolemma contain?
ANS nerves have outpouchings called varicosities.
Vericosities release NTXs via exocyt
osis into a wide synaptic cleft called
a diffuse junction.
No T-Tubules/Troponin
Sarcolemma has pouch like infolds called caveoli
SMOOTH MUSCLE: Contraction contributions
What does contraction involve?
What is it similar to
Is it innervated?
What do NTXs do?
-Neural Regulation
-Similar to skeletal muscle with regard to action potential, but diff nerve types & NTXs can interact
-Innervated by ANS (SNS & PNS)
-NTXs can have diff actions on diff muscles
NEURAL REGULATION
What are the chemical factors that regulate smooth muscle?
Chemical factors that regulate smooth muscle:
1. Hormones (which can produce muscle contraction), Chemicals (ex. gastrin, 5-HT Seretonin.
2.Gases: 02, CO2, & NO (helps blood vessels dilate
3. Changes in pH
NITROGLYCERIN
how does this work in relation to muscle contraction.
Nitro: gets converted in NO to promote cardiac dilation. Helps with heart problems.
CONTRACTION OF SMOOTH MUSCLE
What is the initial signal?
What are the molecules involved?
Calcium is initial signal
Molecules involved: Calmodulin, Myosin Light Chain Kinase, Myosin Phosphate
CALMODULIN
what shape does it have?
what is it?
what does it have?
Dumbell shaped
Protein
With 2 globular lobes connected by alpha helix
MYOSIN LIGHT CHAIN KINASE
what is the abbreviation?
what is it?
what does it do?
MLCK
Its an enzyme
Catalyzes transfer of Phosphate from ATP to regulatory light chain of myosin
MYOSIN PHOSPHATE
what is it?
what does it do?
Its an enzyme
Involved in removing phosphate from Myosin
CONTRACTION OF SMOOTH MUSCLE
Steps
1.AP (Action Potential)
2.Calmodulin binds Ca
3.Produces conformation change in Calmodulin, exposing "active" sites
4. Calmodulin interacts with MLCK
5.MLCK transfers ATP to myosin
6.Myosin can crossbridge with actin
7.As Ca levels drop, myosin phosphatase activates, which removes phosphate from myosin.
8.Contraction terminates
OTHER INTERESTING STUFF
What is succs?
Vecuronium?
Myasthenia Gravis?
Muscular dystrophy?
Botulism?
Succinylcholine & Vecuronium: paralyzes muscles. V lasts longer.
Myasthenia Gravis: loss of ach receptors, causes paralization slowly
Muscular Dystrophy: Genetic, sex-linked, inability to move
Botulism: infection disease