Test 4 : Muscles Flashcards
What are the types of muscle tissue?
- skeleton
- cardiac
- smooth
Skeletal Muscle Features
Location: skeleton
Function: motion, posture, heat production, protection
Appearance: long cylindrical, striated, multinucleated
Control: voluntary
Cardiac Muscle Features
Location: heart
Function: pump blood
Appearance: Branched, striated, single centrally located nucleus
Control: involuntary
Smooth
Location: iris of eyes, walls of hollow organs
Function: motion
Appearance: spindle -shaped cell, non striated, gap junctions
control: involuntary
Do muscles attach directly to bone?
no ma’am!
they attach via myofascial unit
Endomysium
binds the individual muscle fibers together
innermost fascia
Perimysium
groups the muscle fibers together into units (fasicles)
middle fascia
Epimysium
binds fascicles together
Tendon
- Rope like structure
- connective tissue that attach muscles.
ex: part that stands up on your hands
Aponeurosis
sheet like structure
Macroscopic
what you can see with your naked eye
Belly/gastor:
the meat like part, the contractile units of the muscles
Deep fascia
raps around muscle, tough, dense, follow tendon
Fascicles:
what looks like fibers. Run in different directions which adds to muscular strength and function
Microscopic
needs microscope, cells and what is in the muscle
sarcolemma
cell membrane equivalent, holds contents of muscle cell
Sarcoplasm
watery gallantness matrix, that surrounds organelles
Myofibril
(mini fibers) contain the contractile unite called a sarcomere ( contractile unit)
Sarcomere
found in the myofibril
Sarcoplasmic reticulum
calcium
Transverse tubule
important in connecting nerves system and muscular system. Transports sodium from outside to the inside
Triad
the relationship of the terminal systerns to the tubules. sarcoplasmic reticulum r and t tubule
Terminal cisterns
Sac like structures on the end of sarcoplasmic reticulum. Where calcium is stored
What are the charges of calcium and sodium?
Sodium and calcium both have positive charges so they repel
Contractile unit
Where shortening of the muscle takes place.Comprised of a thin filament called actin
Thick filament called myosin, has a binding to boundaries (boundaries = z lines)
What are contractile proteins?
Myosin + actin
What binds sarcomeres together?
Z discs
Actin + Myosin overlapping
dark band called A band
I bands
actin
h zone
myosin
Myosin
- is comprised of multiple proteins and it has a shaft and a head
- Head = cross bridge
In the cross bridge there is a binding site for actin and for ATP (bodies source of energy) - Shaft has a hinge in it = allows it to attach to the actin
Actin
- braided shape
- On actin there are binding sites for myosin
- Binding sites are covered by a regulatory protein called tropomyosin
- Troponin is a regulatory protein bound to tropomyosin and it has a binding site for calcium
Sliding filament mechanism
the way it combines and contracts
what does contraction and relaxation require?
energy - ATP
ATP
the bodies main source of energy
steps for contraction and relaxation
- ATP hydrolysis
- attachment of myosin to actin forming a cross - bridge
- power stroke
- detachment of myosin from actin
Power stroke
causes sliding, produces force
When do muscle cramps occur?
at the end, when you are running low on ATP and don’t have ATP to attach
Functions of Muscle Tissue
- Skeletal movement
- Stabilize posture
- Muscle pumps helps to return blood back to the heart
- Metabolically active so has a function in thermogenesis (temp regulation)
Contractility
the ability to shorten
properties of muscle tissue
- electrical excitability
- contractility
- extensibility
- elasticity
Extensibility
the ability to extended
Elasticity
ability to return to original resting length or shape
Voluntary
– needs a connection between brain, spinal chord and muscle cell
Electrical excitability
Muscle cell is very susceptible to ion movement.
Motor unit
one motor neuron and all the muscle fibers that it stimulates
Neuromuscular junction
Junction between the nervous system and the muscular system
Axon terminal
terminal end
synaptic end bulbs
Within the synaptic end bulb there are synaptic vesicles or bubbles
neurotransmitters
in synaptic vesicles.allows for the transmissions of the action potential to wherever it needs to go
synaptic cleft
There is a space between the structure
Motor end plate
continuation of the sarcolemma. Here there are receptor sites for acedocolean
what opens Na channels and allows for Na to enter the cell which transfers the electrical activity from the nerves system to the muscular system?
Ach go to binding sites and bind if they are open
steps for neuromuscular junction
- action potential causes Ca ++ channels to open causing Ca++ to enter synaptic end bulb
- synaptic vesicles move to synaptic cleft causing the release of ACh
- ACh binds to receptor sites causing ACh receptors to activate and Na+ channels open
- Na+ enters muscle fiber causing muscle action potential
what causes relaxation?
Relaxation occurs from no longer having a stimulus or nervous system information not coming as frequently to the muscles that contract
Motor neuron
one neuron and all the muscle fibers it stimulates. A unit of contraction
-150 fibers per neuron
how does size of motor unit play a role?
Size of the motor unit plays a role in the precision/type of movement in a body part. Ex: muscles for the eye are smaller than muscles for the quad
Motor unit
contract all or none, not partially only fully contract
All or none principle
all the muscles fibers contract or none of them contract.
how can you impact strength?
To impact the strength you can recruit more motor units - this is a learned process.
what allows us to maintain muscle tone?
-Motor units allow us to maintain muscle tone or muscle shape. There is an a syncronis throughout your muscle that allows you to maintain muscle tone
how can you loose muscle tone?
The only way to loss muscle tone is if there is no nervous system communication – flaccid, no action potential (spinal chord)
flaccid
no action potential
Muscle tone
muscles never totally relax which gives them muscle tone
Metabolism
has to be present for life to be sustained
Anabolism
building process that requires energy
Catabolism
: releases energy or yields energy. digestion is an example
ATP:
energy currency. Phosphate breaks off and provides energy.
Creatine Phosphate
only in muscles
how much ATP do we have stored?
We have enough ATP stored for 3 seconds of activity
how much protein molecule creatine can we store?
We can store the protein molecule creatine in our skeletal muscle for 15 seconds of work
what is energy from creatine phosphate do?
Energy from creatine phosphate does not cause muscle contraction. Used to resynthesize the limited store of ATP
what is the only energy we can use to do work?
ATP
Anaerobic glycolysis
takes place in the sarcoplasm (cytosol). Takes glucose and uses it to yield ATP molecules
Hexokinase
traps glucose inside the cell
phosphofructokinase
Glucose is split in two by phosphofructokinase
When is pyruvic acid is made into lactic acid
if there is no oxygen or insufficient oxygen
Lactic acid
Lactic acid when we have sufficient amounts of o2 can go into the blood to the liver and the liver can take the lactic acid and reform glucose.
If you are doing multiple quick bursts of activity…
The lactic acid will lower the PH of the blood and enzymes don’t function well in low PH environments
Anaerobically
have enough energy for about 30-40 seconds of activity
In the presence of O2 the fate of the pyruvic acid is changed
It is changed into a two compound acetyl molecule
Coenzyme a combines with acetyl molecule forming acetylCoA and the CoA takes the acetyl into the mitochondria
Beta oxidation
take long chains of carbon acids and each time it goes through the beta oxidation process it yields a two carbon acetyl molecule and it bonds with CoenzymeA and is transported into the Krebs cycle
Carbohydrates
anaerobic, aerobic, prime fat pathways (so Krebs cycle and transport plain to work efficiently) easer way to get atp
Proteins are an expensive source
takes energy to yield energy.
SRP
sarcoplasmic reticulum
Muscle Fatigue
Inability of muscle to maintain force of contraction after activity
Contributing factors of Muscle Fatigue
- Inadequate release of Ca++ from SRP
- Depletion of creatine phosphate
- Insufficient oxygen
- Glycogen depletion
- Build up of lactic acid & ADP
- Failure of motor neuron to release ACh
what is the least likely cause of fatigue?
Glycogen loss is one of the least likely cause of fatigue
Fused Tetanus
Our muscles need a certain number of action potentials (50-100 action potentials per second) coming from the brain to depolarize it sufficiently enough to allow contraction to take place
The frequency impacts the ability of the muscle contraction to make a movement
You need to send vollies to cause the sarcomere to shorten
Length - tension relationship
Length of the sarcomere. There is an optimal length
Overstretched
ex: when your heart fibrillates. Quivers
Red
slow oxidative
smallest,
- slowest, but have many mitochondria and capillaries they can contract for a long period of time
- Primarily what we use for posture or long activities
white
fast glycolytic
- fastest. Don’t have many mitochondria or capillaries. Used for powerful activities, short durations
- Rapid intense movements, football, lifting weights
pink
half way in-between
- in between, can generate aerobically and anaerobically
- What we use most of the time
Isotonic contractions
produce body movement
Isotonic contractions
length of the muscle changes by shortening or lengthening
Concentric
shortening of the muscle
- Flexing
Eccentric
when the muscle lengthens (usually to decelerate)
- Controlling the arm when you bring it down
They work together
Isometric
no movement takes place, but it stabilizes joints. maintain posture
-Abdominal muscles have to stabilize the pelvis
Muscles have two attachments
Attachment is either via tendon or aponeurosis
Origin
attachment to the stationary bone
Insertion
attachment to the moving bone – always moves towards the origin
An insertion always crosses a joint
Belly/ Gastor
between the tendons where the fleshy portion is
Movements at joints occurs as a result of…
lever system arrangements
Lever
rigid structure that moves around a fixed point
Fulcrum
fixed point or the joint. Point around which movement occurs
Effort
structure that causes movement, muscle insertion
Load or resistance
structure that is being moved.
Mechanical advantage
resistance is closer to the fulcrum
Mechanical disadvantage
resistance is further from the fulcrum
what are the types of levers
1st, 2nd, and 3rd class
1st class
fulcrum is somewhere between the effort and the resistance
- Head moving up
2nd Class
mechanically advantaged
How a wheel barrow works. The way we raise up on our toes to propel ourselves forward
Small effort and small muscle
3rd class
: the effort is always somewhere between the fulcrum and the load
- Most of our our movements are 3rd class, most common
Elbow flexion, knee flexion, hip flexion, hip extenstion
Mechanically disadvantaged but it allows us to move through wider ranges of motions than 1st or 2nd
muscles do not work in …
they do not work in isolation
Agonist
muscle that is preforming the movement.
Antagonist
muscle that must yield (stretch) for movement to take place.
- Usually the agonist and antagonist are on opposite sides of the body
- Movement not muscle
Synergist
muscles that assist one another
fixator
stabilizes a joint
- Contracting isometrically
helpers
perform the same movement
- Elbow flexion – biceps then the brachialis and the brachioradialis
movement is key
Muscles can play any role at any time
