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