Muscles and Muscle Tissue

Question 1

What are the 3 types of muscle tissue in the
human body?

Answer 1

Skeletal, Cardiac, Smooth

Question 1

Muscle tissue transforms ____________ energy into ____________ energy.

Answer 1

chemical, mechanical

Question 2

Which types of muscle tissue are striated?

Answer 2

Skeletal + Cardiac

Question 3

What is the function of each type of muscle
tissue?

Answer 3

Skeletal Muscle Tissue -responsible for voluntary
movements of the body, including actions such as walking, reaching, and
grasping objects.

Cardiac Muscle Tissue - found in the heart and is
responsible for pumping blood, ensuring circulation throughout the body.

Smooth Muscle Tissue -located in various internal
organs and structures, such as the walls of blood vessels and digestive organs,
and it functions involuntarily to propel substances, like blood and food, through
the body’s systems.

Question 4

Which types are voluntary? Involuntary?

Answer 4

Skeletal - Voluntary
Cardiac - Involuntary
Smooth - Involuntary

Question 5

List and define the 4 characteristics common to ALL types of muscle tissue

Answer 5

Excitability (responsiveness)- ability to receive/respond to stimuli by changing its membrane potential

Contractility- ability to forcibly shorten when stimulated

Extensibility- ability to stretch or extend - even beyond resting length

Elasticity- ability to recoil to resting length

Question 6

List and define the 4 functions of muscle tissue.

Answer 6

• Produce Movement- – locomotion and manipulation
  – contraction of the heart
  – blood vessel dilation/constriction
  – movement of all fluids/substances through tracts
• Maintain posture and body position
• Stabilize joints
• Generate heat

Question 7

In order to contract, skeletal muscles require
__________, ____________, and ____________.

Question 8

Be familiar with the equation for cellular
respiration.

Answer 8

C6H12O6 + 6O2 —-> 6CO2 + 6H2O + ATP

Question 9

Where does O2 come from? How about C6H12O6?

Answer 9

O2 comes from the air we breathe

C6H12O6 comes from the broken down carbohydrates in our diet

Question 10

What happens to the CO2 and H20 created?

Answer 10

CO2 is breathed out

H2O is used by the body for maintaining hydration or is excreted through urination, or sweating

Question 11

Define epimysium, perimysium, and endomysium. What type of structures are they? Know what each covers.

Answer 11

Epimysium- most external; dense irregular connective tissue surrounding the entire muscle; may blend with fascia

Perimysium- fibrous connective tissue surrounding fascicles (groups of muscle fibers)

Endomysium- most internal; fine areolar connective tissue surrounding each muscle fiber

Question 12

When epimysium, perimysium, and endomysium are join together what do they become?

Answer 12

Together they become tendons that joins muscles to bones

Question 13

Define origin and insertion. For practice, think
of a muscle. What is its origin? What is its
insertion?

Answer 13

Origin : the immovable or less movable bone

Insertion : the moveable bone

For the biceps brachii, origin is on the coracoid process of scapula, insertion
is merged into a tendon on the radius bone of the forearm

Question 14

A tendon is an example of what type of
attachment?

Answer 14

Indirect : connective tissue wrappings extend beyond muscle as ropelike tendon
or sheetlike aponeurosis (more common!)

Question 15

What is the other type of attachment (not
indirect)? Name a muscle that attaches this
way.

Answer 15

Direct ( Fleshy ): epimysium fused to periosteum or perichondrium

Example is the deltoid

Question 16

What shape is a muscle cell? What are two
cellular organelles that a muscle cell would
have multiple of?

Answer 16

A muscle shape is long and cylindrical

They would have mitochondria and rough endoplasmic reticulum or myofibrils

Question 17

Define sarcolemma.

Answer 17

plasma membrane of a muscle fiber

Question 18

Define sarcoplasm.

Answer 18

cytoplasm of a muscle fiber

Question 19

What are glycosomes?

Answer 19

Sarcoplasm contains many glycosomes – granules of stored glycogen

Question 20

Define myoglobin.

Answer 20

a red pigment that stores Oxygen

Question 21

What are myofibrils? How many might you
find in a single muscle cell?

Answer 21

Myofibrils : densely packed, rodlike elements

A single muscle fiber can contain 1,000s

Question 22

Myofibrils are chains of _________________.

Answer 22

Sarcomeres (basic structural and functional unit of a muscle)

Question 23

Draw out a sarcomere and label the following parts: A Band, I Band, H Zone, M Line, Actin, Myosin, Z Line. Do this over and over until you’ve got it down!

Question 24

What bands make up the dark region? How about the light region?

Answer 24

A bands- dark regions I bands- lighter regions

Question 25

Why is the H Zone a lighter region within the dark region?

Answer 25

H zone appears lighter since it contains only myosin filaments

Question 26

Is actin the thin filament or the thick filament? What about myosin?

Answer 26

Actin- thin filament Myosin- thick filament

Question 27

What are polypeptide chains?

Answer 27

long chains of amino acids bounded by peptide bonds

Question 28

What types of polypeptide chains make up the thick filament? Within the thick filament, where can you find each type of polypeptide chain?

Answer 28

Thick Filaments - composed of the protein myosin. Each myosin molecule contains 2 heavy and 4 light polypeptide chains. Heavy chains intertwine to form myosin tail Light chains form globular myosin heads

Question 29

What is the function of the myosin head?

Answer 29

During contraction, myosin heads link thick and thin filaments together forming cross bridges

Question 30

Define G (Globular) Actin. What is its function?

Answer 30

Actin has kidney-shaped, polypeptide subunits called G (globular) actin G actin subunits bear the sites for myosin head attachment during cross bridge formation

Question 31

Define F (Fibrous) Actin. What is its function?

Answer 31

G actin subunits link together to form long, fibrous F actin 2 F actin strands twist together to form a thin filament

Question 32

List the 2 regulatory proteins bound to actin. What is each of their specific functions?

Answer 32

Tropomyosin and Troponin - regulatory proteins bound to actin that control muscle contraction Tropomyosin - rod-shaped protein, spiral about the actin core and block myosin-binding sites Troponin - globular protein, able to bind to 1-actin, 2-tropomyosin, 3- calcium

Question 33

What role does the protein elastin play? How about dystrophin?

Answer 33

Elastin's main function is to allow tissues in your body to stretch out and shrink back . Elastic Filament - composed of protein titin; holds thick filaments in place; helps to resist excessive stretch and assists with recoil Dystrophin - structural protein that links the thin filaments to the integral proteins of the sarcolemma

Question 34

Broadly, what are the muscular dystrophies? What are some specific symptoms of Duchenne Muscular Dystrophy (DMD)? What protein is impaired in DMD? What does impairment of this protein cause in terms of muscle function? Do you remember how scientists are attempting to cure DMD? I talked about it in class!

Question 35

What is sarcoplasmic reticulum? What is its function?

Answer 35

Sarcoplasmic Reticulum - network of smooth endoplasmic reticulum tubules surrounding each myofibril - Stores and releases calcium on demand - Functions in regulation of intracellular calcium levels - Most tubules run longitudinally

Question 36

What is a terminal cistern? Where can you find them?

Answer 36

Terminal Cisterns - SR tubules that form perpendicular cross channels at the A-I band junction; always occur in pairs

Question 37

What is a T-Tubule? Where can you find them? What is its function?

Answer 37

Tube formed by protrusion of the sarcolemma deep into the cell’s interior – pass from 1 myofibril to the next Occur at A-I band junction - between terminal cisterns T Tubules allow electrical nerve transmissions to reach deep into the interior of each muscle fiber and trigger the release of calcium

Question 38

Together, the 2 terminal cisterns and the T- Tubule are known as the __________?

Answer 38

Triad - area formed from the terminal cistern of one sarcomere, a T tubule, and the terminal cistern of the neighboring sarcomere

Question 39

Protruding proteins from the T-Tubules act as what type of sensors?

Answer 39

voltage sensors – change shape in response to an electrical current

Question 40

Protruding proteins from the SR act as what type of sensors?

Answer 40

form gated channels through which Calcium can be released

Question 41

What happens when an electrical impulse passes through the triad?

Answer 41

T tubule proteins change shape, SR proteins change shape, and calcium is released into the cytoplasm

Question 42

Contraction is generation of ___________ by activation of myosin’s _____________________.

Answer 42

force, cross bridges

Question 43

Which myofilament slides in the sliding filament model? Do actin and myosin change their individual lengths? If not, how does the sarcomere change length?

Answer 43

The actin filaments slide relative to the myosin filaments Actin and myosin do not change their lengths Sarcomere Length Change - Sarcomeres, the basic structural units of muscle fibers, change length as a result of the sliding of actin and myosin filaments. When a muscle contracts, the sarcomeres shorten, bringing the Z lines closer together. When a muscle relaxes, the sarcomeres lengthen, and the Z lines move farther apart.

Question 44

What happens with Z Discs, I bands, H Zones and A bands when the muscle contracts

Answer 44

Ratcheting action shortens the muscle fiber - Z discs are pulled toward the M line - I bands shorten - H zones disappear - A bands move closer together