Human Anatomy - Muscle tissue Flashcards Preview

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Flashcards in Human Anatomy - Muscle tissue Deck (44)

Muscle is the primary tissue in the ______, _____ of ______ _____ and attached to the ________.
Indicate which type of muscle corresponds to each case.

Muscle is the primary tissue in the heart (cardiac), lining the walls of hollow organs (smooth) and attached to the skeleton (skeletal).


Muscle tissue makes up nearly ____ the body mass, around ___%.

Half, 40


What are the function of muscle tissue. Indicate which type of muscle provides the function.

Producing body movements - skeletal
Stabilizing body positions/posture/joints - skeletal (tone)
Movement of substances within the body - smooth for digestive; cardiac for heart
Opening and closing passageways (sphincters - skeletal or smooth)
Producing heat - (shivering) skeletal


What is muscle tone?

Involuntary contraction of a small number of muscle fibres.
Keeps the muscles firm even though they are relaxed.
Does not produce movement.


Tone is essential for what?

Posture, stabilizing synovial joints, maintaining blood pressure.


What are the properties of muscle tissue?



Describe contractiblity.

Muscle cells can contract to generate force.


Describe excitability.

Muscle cells are innervated by nervous impulses.


Describe extensibility.

Muscles can be stretched, especially when opposing muscles contract.


Describe elasticity.

Once stretches, muscles can recoil back to their original length


How is muscle tissue characterized?

1 - Presence or absence of striations.
2 - If the tissue is under voluntary or involuntary control


Describe skeletal muscle. How is it characterized? What does it attach to.

Long, multinucleated cells.
Striated, light and dark bands visible under microscope.
Under voluntary control.
Attaches to bone, skin, fascia.


Describe cardiac muscle.
How is it characterized?
Where is it found?

Shorter in length compared to skeletal muscle, branched and attached by intercalated discs. Uninucleate.
Under involuntary control and striated.
Principle tissue of the heart wall.


Intercalated discs are composed of what tissue type?

Connective tissue


Describe smooth muscle.
How is it characterized?
Where is it located?

Spindle shaped muscle cells with central nuclei.
Non-striated under involuntary control
Walls of hollow organs of the urinary tract, in the respiratory tubes, GI tract, blood vessels and as the erector pili muscle.


Describe the similarities in muscle tissue.

In both skeletal and smooth muscle, muscle cells are know as fibres.
The myofilaments, actin and myosin, are similar in all three muscle tissues.
The plasma membrane is called the sarcolemma.
The cytoplasm is called the sarcoplasm.
The ER is called the SR.


Each muscle is considered an ______.
Other than muscle tissue, it contains what?

Connective tissue
Blood vessels (endothelium and muscle)
Nerves (Nervous tissue)


Describe the miscroscopic anatomy of skeletal muscle.

Fibres are long and cylindrical.
These are huge, striated cells.
Each cell is formed by the fusion of embryonic cells --> embryonic
Nuclei are peripherally located.


Describe a single muscle fibre/cell.

Organelles are replaced with myofibrils
sarcolemma on the outside,
Nuclei pushed to the periphery
lots of mitochondria for energy


What are the different connective tissue sheaths in skeletal muscle?

Endomysium - around each muscle fibre
Perimysium - around fascicles of muscle cells.
Epimyisum - surrounds the whole muscle


What type of CT composes the endomysium?
The perimysium?
The epimyisum?

Endomysium - areolar
perimysium - dense irregular
epimysium - dense irregular


The endomysium, perimysium and epimysium are _______. The endomysium transitions into a _____ composed of ______ ______ CT.

tendon - dense regular CT


Striations result from internal structure of ________.



What are myofibrils?

Long rods within the sarcoplasm.
Specialize contractile organelle of muscle tissue.
Long row of repeating sarcomeres.


What are sarcomeres?

Functional unit of contraction for skeletal muscle.


What are the different components of sarcomeres?

Z-disc (or line)
Thin filaments composed of actin, extend from Z-line toward the centre of the sarcomere
Thick (myosin) filaments - located in the centre of the sarcomere
Titin - stretchy protein


What are the different regions of the sarcomere?

A-band - length of thick filament
I - band: area with only thin filament
H-zone - area with only thick filament
M-line - centre of H zone


What is the SR?

A specialized smooth ER that acts as a calcium storage site.


What are T-tubules?

• T-tubule, invagination of sarcolemma, transmit nervous impulse to the muscle cell, communicating with SR to release calcium


What is the mechanism of contraction for skeletal muscle?

Sliding filament theory:
Myosin heads attach to actin in the thin filaments.
These then pivot to pull the thin filaments toward the centre of the sarcomere.
Filaments slide relative to one another, leading to contraction.


Explain the changes in striation during contraction, i.e. what zones change.

During contraction, the A zone stays the same size.
The I zone gets smaller.
The H zone potentially disappears (contingent on the amount of contraction).
Z-disc or line stays the same size but adjacent ones get closer to one another.


What is titin?

Spring-like molecule in sarcomeres which account for the elasticity and extensibility of myofibrils.

It holds the thick filaments in place.
Unfolds when the muscle is stretched and helps sarcomeres return to their resting length.


Describe rigor mortis.

Occurs 3-4 hours after death.
Cell membranes become leaky and calcium leaks out of SR, causing myosin to bind to actin.
The myofilaments cannot detach since ATP synthesis no longer occurs.
This leads to a tensing of muscles.
This goes away after 24 hours due to lysosomal digestion of myosin and actin.


Why do slaughter houses hang freshly butched animals?

Prevent rigor mortis so meat stays tender.
Gravity prevents rigor mortis that would generally occur post-mortem


What are the different types of skeletal muscle fibres?

Fast oxidative, slow oxidative, fast glycolytic


How are the different types of skeletal muscle fibres categorized?

On the basis of how fast they contract and on how they manufacture ATP.


Describe slow oxidative fibres.
What colour are they?
How many mitochondria do they have?
Categorize them.
What functions are they adapted for?

Oxygen dependent fibres that contract slowly and are fatigue resistant as long as oxygen is present.
Use ATP at a slow rate and are oxygen dependent.
They have many mitochondria and are richly supplied with capillaries.
They are red in colour due to the abundance of myoglobin.
They are adapted for maintaining posture and aerobic endurance type activities.


Describe fast oxidative fibres.
Categorize them.
What colour are they?
What are they adapted for?

Oxygen dependent, use ATP quickly.
Somewhat fatigue resistant.
Pink in colour.
Have high myoglobin content and a rich supply of capillaries.
More powerful than SO fibres.
Adapted for activities such as walking.


Describe fast glycolytic fibres.
What colour are they?
Categorize them.
What are they adapted for?

Contain little myoglobin and few mitochondria.
Contain more myofilaments and generate lots of force in a short period.
Depend on anaerobic pathways to generate ATP and use it quickly.
Adapted for short, intense exercises such as weightlifting and springting


What are the colours of the different skeletal muscle fibres?

SO - red
FO - pink
FG - white


Most muscles contain an equal mixture of all three _____ types.
Neck, back and leg muscles have a higher proportion of what?
Shoulder and arm muscles have a higher proportion of what types of fibres?


Slow oxidative

Fast glycolytic


Cardiac cells would have more ___ fibres.



When gaining muscle size, one doesn't increase the number of muscle fibres/cells but instead _____?

increases the number of myofibrils in the cells


Explain DOMS.
How is it related to gainz?

Delayed onset muscle soreness.
Cause my micro-tears in the muscle fibres.
Inflammatory response results in swelling in the endomysium (CT surrounding muscle fibres).
Swelling compresses the nerve endings in the muscles, leading to soreness.
Tears stimulate increase production of myofibrils and myofilaments, resulting in increased muscle size.