Chapter 43 - Muscles, Bones and Body Movements

Muscle cells are arranged in bundles surrounded by ___________

Connective tissue

The 3 muscle tissue types are:

Skeletal, cardiac, smooth muscle tissues

___________ forms the body flesh

Skeletal muscle tissue

___________ makes the heart walls and surrounds blood-filled chambers

Cardiac muscle tissue

___________ makes up walls of hollow organs and are non striated muscles

Smooth muscle tissue

Skeletal muscles are attached to skeleton bones by connective tissue cords called _____________________

Tendons

The 2 types of muscles cells are ___________ or _____________

Striated and smooth muscle cells

___________ muscles cells have no banding pattern while ___________ muscle cells have alternating light and dark bands

Smooth, Striated

These bands are regular arrangement of contractile protein called _____________________

Myofilaments

List the functions of skeletal muscles

Contraction, protection of thoracic, abdominal and pelvic organs, stabilize joints, maintain posture and maintain homeostasis by generating heat — Contractility, Extensibility, Elasticity

What are the similarities and differences between skeletal muscle tissue and cardiac muscle tissue

Both are striated muscles (have alternating light and dark bands). Skeletal muscles are voluntary and controlled by the somatic nervous system while cardiac muscles are involuntary and controlled by the autonomic nervous system

Muscle tissue is avascular

False, muscle tissue is highly cellular and vascular. Extensive networks of blood vessels in the muscle tissue to transport oxygen and nutrients

Contraction of cardiac tissue causes propulsion of internal material

False, contraction of cardiac tissue causes blood propulsion while contraction of smooth tissue causes propulsion of internal material

Skeletal muscles are controlled by the autonomic nervous system

False, by the somatic nervous system because it is voluntarily

Muscle cells are derived from embryonic mesoderm

True

Skeletal and Cardiac muscle cells are striated and mononucleated

False, both are striated but only skeletal muscle cells are multinucleated

Unfused Myoblasts remain as myosatellite cells the repair damaged muscle tissue

True, multinucleation of muscle fibers is due to myoblast fusions & if not fused → used for repair of damaged muscle cells

A bundle of Skeletal muscle fibers

Fascicle

Blood Vessel

B

Connective tissue that surrounds the entire muscle tissue

Epimysium

Connective tissue that surrounds and separates the fascicles

Perimysium

Bone

E

Connective tissue between the fibers in the fascicles

Endomysium

Tendon

G

Muscle cell

Muscle fiber

The plasma membrane of a muscle fiber is called ___________ while the cytoplasm is _____________

Sarcolemma, sarcoplasm

__________________ Ca2+ storage in muscles

Sarcoplasmic reticulum

A myofibril is surrounded by the __________________

Sarcoplasmic reticulum

The contraction unit of a myofibril is __________________

Sarcomere

_________ and _________ are the contractile proteins in myofibrils that generate force during contraction

Actin, Myosin

_______ and _________ are the regulatory proteins in myofibrils that switch contraction on and off

Troponin, tropomyosin

Anchors thick filaments in the middle of the sarcomere

M line

Light region of thin filaments only

I band

Separates sarcomeres from each other

Z discs

Region of thick filaments only

H zone

Dark region that extends the region of thick filaments and the part of thin filaments that overlap

A band

The repeating unit of a skeletal muscle fiber is the

Sarcomere

Interactions between actin and myosin filaments are responsible for

Muscle contraction

The ________ of muscle contraction depends on interactions between actin and myosin proteins

Sliding filament model

In muscle contraction, thick filaments (myosin) slide over thin filaments (actin)

FALSE! Thin filaments (actin) slide over thick filaments (myosin) toward the center of the A band

The plasma membrane of a skeletal muscle is called the _____________, and it surrounds the cytoplasm of the muscle fiber called the _____________

Sarcolemma, sarcoplasm

A tubular network of membrane complex around each myofibril is _____________________

Sarcoplasmic reticulum

The sudden change of ______ causes a contraction

Membrane potential

Which of the following best describes the term sarcoplasmic reticulum?

Storage and release site of calcium ion

Tubes that extend from the surface to the interior of a muscle fiber are called _____ and ______ travel along them

T tubules and action potentials

All regions of a muscle fiber contract at the same time

TRUE!

What are the two elements important for a muscle contraction?

Ca2+ and ATP

An increase in [which ion concentration] triggers the _______, a series of molecular events in which repeated power strokes pull the actin thin filament over the myosin thick filament – producing muscle contraction

[Ca2+] triggers the crossbridge cycle

Blocks Ach release in neuromuscular junctions and body muscles, such as the diaphragm, become paralyzed and respiratory failure may cause death

Botulinum toxin

An alkaloid used to poison arrows - blocks Ach from binding to its receptors in muscle fibers and body muscles, such as the diaphragm become paralyzed

Curare

Commonly known as “stiffness of death”

Rigor mortis

What is the name of DMD?

Duchenne Muscular Dystrophy

DMD is categorized as a - linked ___ trait genetic disorder. It majorly affects the ____ gene

X- linked recessive trait genetic disorder. It majorly affects the dystrophin gene

What are some common symptoms and features observed in individuals affected by DMD?

Enlarged calf

Intensity of contraction is low

Slow twitch muscle fibers

Large in diameter

Fast muscle fiber

Paler in color

Fast twitch muscle fibers

Can remain contracted for relatively long periods

Slow twitch muscle fibers

Contain relatively few/fewer mitochondria

Fast twitch fiber

Contain densely packed mycrofibrils

Fast twitch muscle fibers

Help stand and hold posture for long periods of time

Slow muscle fiber

Powerful contractions

Fast twitch fiber

Fatigue rapidly

Fast twitch fiber

Deeper red color

Slow twitch fiber

Postural muscles of back, muscles of lower leg of flightless birds

Slow twitch muscle fiber

All the muscle fibers controlled by a single motor neurons constitute a ____ ___

Motor Unit

The size of a motor unit is an indication of how ___ the control of movement is

Fine

For a delicate movement, only a ___ efferent neurons fire – for more powerful movements, ___ efferent neurons fire

Few, a lot of

What type of skeleton consists of a body compartment or compartments filled with water/body fluids? Give an example of an organism?

Hydrostatic skeleton, earth worm

What type of skeleton has a rigid external body covering that supports and protects the internal tissue? Give an example of an organism?

Exoskeleton, roach

What type of skeleton consists of internal body structures such as bones that support and protect soft tissue? Give an example of an organism?

Endoskeleton, human

The two major division of the human skeletal system are the ___ _____ and the ________ _____

Axial skeleton and the Appendicular skeleton

Osteocytes

Mature bone cells

Osteoblasts

Bone matrix forming cells (build bone)

Osteoclasts

Bone absorbing cells (destroy bone)

Give an example for a ball and socket joint and a hinge joint (-_-)

Ball and socket joint - Shoulder and hip joint, Hinge joint - Knee and elbow joint

Muscle tissue have

Ability to contract

Muscle cells

Called muscle fibers can undergo shortening and thickening

Skeletal muscle

Muscles attached to bones, Controlled by conscious effort – voluntary muscles, Striated muscles – alternating arrangement of contractile elements actin and myosin forming light (isotropic) and dark (anisotropic) bands, Peripherally arranged nuclei; multinucleated, Nerve cells stimulate a skeletal muscle cell to contract, Function: The muscles are built of skeletal muscle tissue that produce movement of the head, trunk and the limbs

Cardiac muscle

Only present in the heart, Striated, and branched, Joined end to end forming networks, by intercalated discs, A single centrally located nucleus, Controlled involuntarily, Function: Pumps blood through the heart and blood vessels

Each muscle fiber is surrounded by a ____________, with an enclosed ____________ containing numerous threadlike ____________ that are arranged parallel to one another

Sarcolemma, sarcoplasm, myofibrils

Myofibrils

Play a fundamental role in muscle contraction, Contain two types of contractile elements – actin (thin filaments) and myosin (thick filaments)

Regulatory proteins

Troponin and tropomyosin

The entire muscle is surrounded by an ___________ which is continuous with ___________ that ultimately attach the muscles to bones

Epimysium, tendons

Fascicles are surrounded by

Perimysium

Each muscle fiber within a fascicle is covered by an

Endomysium

Myosin filaments (thick filaments)

Contains about 300 myosin filaments, half of this pointing to opposite ends, Each myosin molecule consists of a pair of myosin subunits twisted into a double helix, with the tails pointing towards the M line, containing myosin heavy chain, Myosin tails form the shaft while the heads project outward, The head is connected to a long double helix tail, The head bends towards the adjacent actin filaments to form the cross bridges, The heads contain two light chains each and an actin binding site and an ATP binding site

Actin filaments (thin filaments)

Twisted strands of F-actin or filamentous actin, Each F-actin contains individual strands of 300-400 G-actin or globular actin, G-actin contains a myosin binding site, Additional regulatory proteins include : Tropomyosin and troponin, Tropomyosin covers the active sites on the G-actin and prevents myosin binding, There are three troponins – one binds to G-actin, the second binds to the tropomyosin and the third binds to Ca2+

Sarcomere

The structural and functional unit of muscle contraction, Spans between two Z lines

A-band

The zone of overlap containing both actin and myosin

I band

Lighter and less dense region that contains only actin filaments

H-zone

A narrow region in the center of each A band that contains thick filaments but no thin filaments

M line

Region at the center of the H zone that holds the thick filaments at the center of the sarcomere

Muscle fatigue

A muscle exercised strenuously for a prolonged period may lose its ability to contract, a condition called fatigue

Botulinum toxin

Blocks Ach release by preventing synaptic vesicles to fuse with the post-synaptic cell membrane

Curare

Blocks Ach from binding to its receptor

Rigor mortis

Lack of ATP after death. Leave the myosin bound to actin in the rigor state

Muscle twitch

One way a muscle responds to a stimulus

Summed twitches

One way a muscle responds to a stimulus

Tetanus

One way a muscle responds to a stimulus