Muscular System Flashcards by India Davis

Describe the morphology of skeletal muscle cell

extremely long and cylindrical shape
Nuclei are peripherally located
Cells are multinucleate
Striated

How well did you know this?

Not at all

Perfectly

Why skeletal muscle fiber is multinucleated?

B/c there’s embryonic mesoderm cells that divide and increase

How well did you know this?

Not at all

Perfectly

What is the functional organelle of skeletal muscle fiber?

Myofibrils

How well did you know this?

Not at all

Perfectly

What is the smallest functional unit of muscle fiber?

Sarcomeres

How well did you know this?

Not at all

Perfectly

Do muscle cells divide? Describe cellular differences that are associated w/ muscular “hypertrophy” vs “atrophy”.

Muscle cells don’t divide

Increase in cell size (hypertrophy) vs decrease in cell size (atrophy)

How well did you know this?

Not at all

Perfectly

Describe in detail the 5 major structural components of a sarcomere

Z disk(c): Boundaries of each sarcomere
Actin (thin) myofilament: Extend from Z disc towards center of sarcomere
Myosin (thick) Myofilament: Located in center of sarcomere
M-Line: Bisects the myosin myofilaments
Titin: Springlike molecule that resists overstretching

ALL ARE PROTEINS

How well did you know this?

Not at all

Perfectly

What is the source of skeletal muscle fibers being striated?

Source of striation is myosin and actin myofilament

How well did you know this?

Not at all

Perfectly

What are the three regions of the myofibril?

I Band
H Zone
A Band

How well did you know this?

Not at all

Perfectly

What happens in the A band?

More and thicker structures that allows for less light to pass through (More myosin)

How well did you know this?

Not at all

Perfectly

What happens in the I band?

Less structure and allows more light to pass through (no myosin)

How well did you know this?

Not at all

Perfectly

What happens in the H zone?

Occurs in less structured middle of the A band (no actin)

How well did you know this?

Not at all

Perfectly

What structures can be found in the I band?

Z-Disc, Titin, and Actin

How well did you know this?

Not at all

Perfectly

What structures can be found in the A band?

Myosin, actin, m line, and titin

How well did you know this?

Not at all

Perfectly

What structures can be found in the H zone?

Myosin, M line, and titin.

How well did you know this?

Not at all

Perfectly

What happens to the 3 regions during full contraction?

A band doesn’t change in size
H zone disappears
I band gets smaller

How well did you know this?

Not at all

Perfectly

Describe conducting system of skeletal muscle to trigger muscle contraction

Neurotransmitters are released from the ends of somatic motor neurons that stimulate sarcolemma
Action potential spreads throughout the sarcolemma of muscle cells
Action potential hits deeper and hits sarcoplasmic reticulum, which triggers it to release calcium inside the cell
Once calcium is released; actin and myosin are triggered to slide and create contraction of sarcomere

How well did you know this?

Not at all

Perfectly

What is rigor mortis?

Stiffness of skeletal muscle after death

How well did you know this?

Not at all

Perfectly

What causes rigor mortis, and how muscle relaxes after RM?

Cause: Sarcoplasmic reticulum leaks calcium signaling myofibrils to contract (body stiffens)

Relaxation: As proteins denature, actin and myosin detach then the body relaxes

How well did you know this?

Not at all

Perfectly

What is a bundle of muscle fibers called?

Fascicle or fasciculus

How well did you know this?

Not at all

Perfectly

What are the 3 connective tissues of skeletal muscles?

epimysium
perimysium
endomysium

How well did you know this?

Not at all

Perfectly

What is epimysium?

Fibrous covering of whole muscle

How well did you know this?

Not at all

Perfectly

What is perimysium?

Fibrous covering of fascicle

How well did you know this?

Not at all

Perfectly

What is endomysium?

Fibrous covering of a single cell (muscle fiber)

Describe origin and insertion of a skeletal muscle

Origin: One end of muscle acts as an anchor (doesn’t move)

Insertion: Other end attaches to the bone that is moving (moves during contraction)

What's tendon?

Structure that connects muscle to bone; made of dense regular proper connective tissue

What's aponeruosis?

A flat tendon

When you extended your cubital joint, what are the prime mover, and antagonist muscles?

Prime mover (agonist): Triceps Antagonist: Biceps

What are characteristics that muscles names are based on? (7)

- location - size - shape - orientation of fasciculi - origin/insertion - # of heads - Function

What are two muscles based on location?

- Pectoral - Brachial

What are 2 muscles that are based on size?

- gluteus medius - gluteus maximus

What are 2 muscles based on shape?

- deltoid - trapezius

What are 2 muscles based on orientation of fasciculi?

- rectus - oblique

What are 2 muscles based on origin/insertion?

- digiti - carpi

What are 2 muscles based on # of heads?

- biceps - triceps

What are 3 muscles based on function?

- extensor - flexor - pronator

What is a primer mover?

Primarily responsible for generating movement

What is a antagonist?

Muscle that does the opposite of th agonist

What is a synergist?

Muscle that helps out

What does the fixator do?

Stabilize one part of the body during movement of another part

When you flex your cubital joint, what are the prime mover, synergist, and antagonist?

Primer Mover - Biceps Antagonist - Triceps Synergist - Brachialis

What are the 13 characteristics of skeletal muscles?

1. cell size: extremely long 2. nuclei? : multinucleated 3. shape: cylindrical 4. location: attached to the bone 5. sarcomeres? Yes 6. striated?: Yes 7. Interconnected?: No 8. Sarcoplasmic reticulum?: Yes 9. Transverse Tubules?: Yes 10. Source of calcium: Sarcoplasmic reticulum 11. Speed of contraction: very rapid 12. Nervous control: Voluntary 13. Fatigue: Tires rapidly

What are the 13 characteristics of cardiac muscles?

1. cell size: normal cell size 2. nuclei? : mononucleated 3. shape: cylindrical branched 4. location: heart 5. sarcomeres? Yes 6. striated?: Yes 7. Interconnected?: Yes 8. Sarcoplasmic reticulum?: Yes 9. Transverse Tubules?: Yes 10. Source of calcium: Sarcoplasmic reticulum & external (blood) 11. Speed of contraction: rapid 12. Nervous control: autorhythmic involuntary 13. Fatigue: does not tire

What are 13 characteristics of smooth muscles?

1. cell size: slightly longer cell size 2. nuclei? : mononucleated 3. shape: spindle 4. location: walls of hollow organs and tubes 5. sarcomeres? no 6. striated?: no 7. Interconnected?: Yes (GI Tract) and No (Eye Iris) 8. Sarcoplasmic reticulum?: no 9. Transverse Tubules?: no 10. Source of calcium: External blood 11. Speed of contraction: Slow 12. Nervous control: Involuntary 13. Fatigue: Does not tires (Latches)

Difference b/w multiunit and visceral smooth muscles?

Multiunit: are not interconnected, has precisely controlled movement, and example is the iris (eye) Visceral: Interconnected like cardiac muscle and has rhythmic pulsating contractions

What are the 5 functions of the muscular system?

- Produce movement of skeleton - Maintain posture and body position - Supports soft tissue - Guard entrances and exits - Generate heat

What are skeletal muscle cells also called?

- Muscle fibers

Where do muscle tissues develop from?

- Myoblasts fuse together to form muscle fibers

What are sarcomeres?

Long row of repeating segments that consists of the smallest functional unit of muscle cell

What is the sliding filament theory?

Actin slides towards myosin during contraction

What is the sarcolemma?

The muscle cell membrane

What is transverse tubules?

Folded sarcolemma tubules that conduct electrical impulses

What is the sarcoplasm?

Cytoplasm of the muscle cell/fiber - Contains sarcoplasmic reticulum

What is the sarcoplasmic reticulum?

Network of membranous channels around each myofibril - stores calcium and is continuously pumping calcium in and out

What is the triad?

Connecting point b/w surface signal of the T tubule and the two terminal cisterns of sarcoplasmic reticulum

What is the neuromuscular junction?

The link b/w nervous system and muscular system in which the "synapse" or space where motor neurons meet muscle

What neurons dictate the contraction of skeletal muscle fibers?

Somatic motor neurons