lecture review muscles
-Lightest area between A-bands composed of actin only - Z-discs bisect the light colored I-bands
I-bands
Result in sustained fluttering contraction
Incomplete tetanus
Which of the following is not a general function of skeletal muscles? 1. voluntary movement of head, face, etc. 2. involuntary movement of the visceral organs 3. provides 85% of body heat 4. provides 40% of body mass 5. Participates in involuntary spinal cord reflexes
Involuntary movement of the visceral organs
Increase in number of muscles or motor units being activated by stimulus
Recruitment
When its work is done, the muscle fiber relaxes and returns to resting length
Relaxation
Muscle cells respond to stimuli in a unique way by producing an electric current that travels along the plasma membrane and triggers CONTRACTIONS OF THE CELL
Responsiveness
Make up a specialized muscle cell membrane
Sarcolemma
Cancers of the muscles or connective tissue
Sarcomas
The contractile functional unit of the muscle fiber is
Sarcomere
Make up a specialized muscle cell cytoplams
Sarcoplasm
Make up a specialized muscle cell smooth ER
Sarcoplasmic Reticulum
The specialized muscle cell smooth ER
Sarcoplasmic reticulum
Aponeuroses
Sheet-like extension of fascia connecting Muscle to Muscle
Muscle fibers with contract to their fullest extent when exposed to threshold stimulus, true or false
True
Relaxation: Tropomyosin returns to a position where active sites are blocked, true or false
True
Whole muscles will contract to varying degrees depending on the nature of the stimulus. True or false
True
sacromere/muscles fiber lengthens, thus relaxation has occurred, true or false
True
One complete muscle contraction and relaxation is called...
Twitch
Skeletal muscles are also known as...
Voluntary muscle, striated muscle
Neuro-muscular Junction location
Wherever motor neurons interface muscle fiber & Never meets muscles
Exitation
action potential in the nerve fiber lead to action potentials in the muscle fiber
When muscle contraction lacks even a partial relaxation & contraction fuse into a smooth, prolonged contraction
complete tetanus
- unique in their ability to SHORTEN substantially when stimulated - this enable them to exert tension on other tissue to which they are mechanically coupled to create movement
contractillity
When muscle cell is stretched & released, it recoils to a shorter length (pull on it, it'll pounce back)
elasticity
Excitation-contracting coupling
event that link the action potentials on the sarcolemma to activation of the myofilaments, preparing them to contract
Synaptic cleft
gap between motor neuron and muscle fiber at neuromuscular junction Motor endplates of muscle cell houses Ach-receptor sites
Sub-cutaneous fascia
lies deep to the skin
State of continued partial muscular contraction necessary for...
maintaining posture & breathing
Ach binds to Ach-receptor sites on...
motor endplate stimulating motor impulses
Neuro-muscular Junction structure
motor neuron synaptic knob with synaptic vesicles containing the neurotransmitters acetylcholine (Ach)
A red pigment which Binds O2 until needed for muscular activity
myoglobin
It form cross bridges with G-actin when contracting
myosin heads
Neuro-muscular Junction function
relay nerve impulses from motor neuron to muscle fiber where it then becomes a motor impulse
specialized plasma membrane
sacrolemma
Constituting 1 contractive unit
sarcomere
The muscle shortens because the individual sarcomeres shorten, pulling the Z-dics closer together
sarcomere
dendrite of motor neuron is..
stimulated
Increase frequency of stimulus does not allow muscles to completely relax before next contraction happen, thus wave summation
summation
Any stimulus greater than maximal stimulus
supra-maximal stimulus
Deep fascia
surrounds & penetrates whole muscles
Has a gated channels in its membrane that can release a flood of calcium into the SACROPLASM
terminal cisternae
It act like a switch to determine when it can contract and when it cannot
tropomyosin & troponin
Regulatory proteins of a muscle
tropomyosin & troponin
Dark peripheral boundaries of sarcomere
z-discs
Why the skeletal m. cell is MUTLINUCLEATED?
- for directing protein synthesis - Because they form by the fusion of embryonic cells called myoblasts
general function of muscles
-85% of the body's heat through glucose catabolism -approximately 40% of mass of body
Skeletal muscle tissue STRUCTURE
-Striated muscle cells (MUSCLE FIBERS) - CROSS STRIATIONS - MANY NUCLEI
general function of skeletal muscular
-controls VOLUNTARY MOVEMENT of head,face,trunk,limbs -POSITION OF THE BODY (sitting&standing) -participates in involuntary spinal cord REFLEXES
Five universal characteristics of muscle are?
1. Responsiveness (excitability) 2. Conductivity 3. Contractility 4. Extensibility 5. Elasticity
synaptic end-foot releases..
Ach
Skeletal muscle tissue LOCATION
Attached to various bones of skeleton by TENDONS
Located in the middle of Thick flament with no heads
Bare zone
Which of the following is not a structure of a sarcomere? A-bands H-bands or zones I bands Z lines or discs CB bands
CB bands
Troponin contains a.....
Ca++ receptors
Cancers of the epithelial tissues are...
Carcinomas
Make up a specialized muscle cell reservoir for calcium ions
Cisternae
- Stimulation of a muscle cell produces more than a local effect - local electrical change triggers a wave of excitation that travels rapidly along the cell and initiates process leading to contraction
Conductivity
Skeletal muscle tissue FUNCTION
Contract (shorten) & Relax (lengthen)
Muscle fibers develop tension and may shorten
Contraction
Tendons
Cord-like extension of fascia connecting Muscle to Bones
Sub-serous fascia
Covers organs and body cavities
Striations of striated muscle consists of
Dark A- bands alternating with light I-bands
The structure that consists of long, twisted chain of bead like molecules making up most of the the thin filament
F- Actin
Fibrous actin referred to as...
F-actin
A bundle of muscle fibers is called a(n)
FASCICLE
Acetylcholine is an enzyme that removes the acetylchoinesterase from the receptor site of a muscle fiber, and prevents the muscle from contracting more, true or false
False
The thick muscle filaments are made up of F-action filaments, which are chains of G-actin molecules, true or false
False
The thin muscle filaments are made up of the protein myosin, true or false
False
The entire muscle is covered by an..
Fascia
The primary molecule of the thin myofibril (the individual bead like molecule) that contains the active sites is
G-actin
Tropomyosin blocks the active sites of
G-actin
Troponin binds to...
G-actin, tropomyosin, & calcium ions
provides stored energy for muscle contraction
Glycogen
sarcoplasm contains...
Glycogen & myoglobin
Area of A-band composed of Myosin only
H-band
Muscles comprise about what percent of body mass on average
40%
A triad consists of
A T-tubule and two cisternae
May be likened to 200-500 such"golf clubs" with their heads directed outward in a spiral array around the bundle
A thick filament
- where myosin & actin myofilaments overlap -primary reason for cross-striations -darkest area
A-bands
darkest area
A-bands
Structures of a sarcomere include
A-bands, H-bands or zones, I bands, Z lines or discs
Responses carried out by muscles or glands are known as...
Effectors
In striated muscles, each muscle fiber is surrounded by ...
Endomysium
In striated muscles, each bundle or group of muscle fasiculi(fascicles) is surrounded by an...
Epimysium
- able to stretch back after contraction - muscle fibers can safely stretch to as much as 3 times their contracted length
Extensibility
stimulus causing maximum contraction of muscle
Maximal stimulus
Skeletal muscle cells are____ because they form by the fusion of embryonic cells called_____.
Multi-nucleated, myoblasts
ATP allows myosin head to pull actin molecule toward center of sarcomere
Power stroke
The small amount of muscle contraction that occurs in most muscles at rest is called
Muscle tone
Many thread-like rods extending full length of muscle fiber & It fill most of the muscle cell
Myofibrils
composed of protein myofilaments
Myofibrils
The structure that makes up the thick filament
Myosin
when muscle fiber is relaxed, tropomyosin blocks the active sites of G-actin & prevents....
Myosin from binding to it
In striated muscles, each individual muscle fascicle is surrounded by an ...
Perimysium
The only cell in your body that have more than 1 nuclei
Skeletal muscle cell
Each A-band consists of a thick filaments lying side by side
Striations
Neuro-muscular Junction
Synapse of a motor neuron & muscle fiber
Action potential travels along neurilemma of axon to....
Synaptic end-foot
Make up a specialized muscle cell structure to carry electrical current from outside the cell to inside the cell
T-tubules
Which very specific structure of the neuron contains the vesicles of neurotransmitters?
Terminal End-foot
Made of 2 intertwined strands of the protein Fibrous actin
Thin filaments
Increased strength of stimulus caused increased strength of contraction
Treppe
The structure that is a long modular strand that covers and blocks the active sites on the thin filament is called
Tropomysin
The globular molecule that binds with the long modular strand that covers and blocks the active sites on the thin filament to block the active site, and binds with C++ to move that structure and exposes the active site
Troponin
A threshold stimulus is the minimal stimulus required for a single muscle twitch, true or false
True
ATP is the energy molecule produced by the Mitochondria, True or False
True