Study Guide for Exam III 10/28/2013
Articulations or Joints
Discuss the structural classification and the functional classification of joints
Name the 3 types of fibrous joints.
Name the 2 types of cartilaginous joints.
Name the 6 types of synovial joints.
Describe the characteristics of the articulating surfaces of bones at each type of synovial joint.
Name the type of synovial joint that allows us to motion “no.”
Name the type of synovial joint that allows us to motion “yes.”
Give the only location in the human body for a saddle joint.
Define: menisci, bursae, and tendon sheaths.
Define: endomysium, perimysium, epimysium, fascicles, tendons, sarcolemma, sarcoplasm, sarcoplasmic
reticulum, myoglobin, sarcomere, Zline, H zone, A band, I band, triad, and motor unit.
Describe the neuromuscular junction. What is the motor end plate?
Name the 3 proteins in a thin filament. What is the function of tropomyosin in a relaxed skeletal muscle?
Name the 3 subunits of troponin. Which troponin subunit is bound to actin?
What is the function of calcium in skeletal muscle contraction? What is the consequence of the power
Describe the sequence of events in ExcitationContraction coupling.
Describe the role of ATP in skeletal muscle contraction. Differentiate between muscle fatigue and rigor
Define the sliding filament mechanism. List structures that: Shorten when a skeletal muscle contracts.
Remain the same when a skeletal muscle contracts.
Discuss the factors that affect the strength of skeletal contraction.
Name and give the characteristics of the 3 types of skeletal muscle fibers: Which type is fatigable and why?
Which type is also known as red fibers and why? (From the lecture and the slides, I don’t have notes on fast
Define isotonic and isometric contractions.
Compare and contrast the structures and mechanism of contraction for skeletal and smooth muscles. What
is the function of calmodulin in smooth muscle contraction? Describe the role of ATP in smooth muscle
How does excitationcontraction coupling in smooth muscle differ from skeletal muscle?
What is the “calciumentry calciumtrigger” mechanism?
Name the structures present in skeletal muscle fibers that are absent from smooth muscle cells and discuss
the functions of these structures.
Compare and contrast skeletal muscle and cardiac muscle.
Compare and contrast smooth muscle and cardiac muscle.
Sample exam questions:
Discuss function of calcium in skeletal v. smooth muscle
Name 2 differences between neuromuscular junction and diffuse junction
What training increases endurance? List 3 structural differences.
Discuss 2 similarities between single unit smooth and cardiac muscle
T/F Cardiac muscle cells lack triads
T/F In smooth muscle, thin filaments are anchored by zdiscs
T/F Skeletal muscle EC coupling, calcium enters from extracellular fluid Chapter 8: Articulations (Joints) 10/28/2013
Joints: articulations (functional class of the skeletal system); sites where at least 2 bones meet in the
human body Chapter 8: Articulations (Joints) 10/28/2013
Classification of joints has 2 types: functional and structural. The structure of a joint determines its function.
Functional classification is based on the amount of movement allowed at the joint. There are 3
functional classes of joints:
Synarthrotic joints (synarthroses): immovable joints
Amphiarthrotic joints (amphiarthroses): slightly movable joints
Diarthrotic joints (diarthroses): freely moveable joints
Structural classification is based on the material that binds the bones at the site, and the absence
or presence of a joint cavity. There are 3 structural classes of joints:
Fibrous joints: material binding the bones is dense regular connective tissue that exhibits strength.
Joint cavity is absent. There are 3 types of fibrous joints:
Sutures: located only between bones in the skill, functional class changes with age (baby skulls have
Amphiarthrotic sutures to accommodate growth and expansion; adult skulls have Synarthrotic sutures,
acting as a protective helmet of the brain when growth and expansion end)
Syndesmoses: 2 types – bones connected by ligaments/cords (Synarthrotic) or bones connected by
interosseous membrane/connective tissue (Amphiarthrotic) (ex. ankle joint)
Gomphoses: located only between the teeth and the bony alveolar sockets (root and opening in the
mandible); also known as “peg in a socket” joints. All Gomphoses are Synarthrotic joints.
Gomphoses become Amphiarthrotic with periodontal disease, which results in tooth loss.
Cartilaginous joints: material binding the bones is cartilage (either hyaline or fibrocartilage). Joint
cavity is absent. There are 2 types of cartilaginous joints:
Synchondroses: binding material is hyaline cartilage (Synarthrotic); ex: epiphyseal plates
Symphyses: binding material is fibrocartilage (Amphiarthrotic); ex: intervertebral discs, pubic symphysis
Synovial joints: material binding the bones is ligaments (dense regular connective tissue). Joint cavity
is present, and is enclosed by the articular capsule. All synovial joints are diarthrotic joints. There are 6
types of synovial joints, depending on the shape and structure of the articulating surfaces of the bones:
Plane joint: articulating surfaces of both bones 1 and 2 are flat; allows for gliding movement (ex:
Hinge joint: articulating surface of bone 1 is cylindrical and the articulating surface of bone 2 is a trough
(cylinder sits deep into trough to allow back and forth movement); allows for flexion and extension (ex:
elbow joint, knee joint)
Pivot joint: articulating surface of bone 1 is a rounded protrusion and the articulating surface of bone 2 is
a ring or sleeve (composed of bone cartilage); allows for rotational movement (ex: atlantoaxial joint,
which allows for us to move the head side to side and to motion “NO”)
The dens (odontoid process) of the axis articulates with the atlas to rotate around the dens. Due to the
powerful muscles of the neck and chest, complete rotation of the atlas/head is prevented. Chapter 8: Articulations (Joints) 10/28/2013
Condyloid joint: articulating surface of bone 1 is an oval protrusion, articulating surface of bone 2 is an
oval depression; allows for flexion, extension, abduction, adduction, and circumduction movement. (ex:
atlantooccipital joint, which allows for us to move head up and down to motion “YES”)
Occipital condyles at the base of the skull articulate with the oval depression of the superior articular facets
of the atlas.
Saddle joint: articulating surface of bone 1 is either convex or concave, articulating surface of bone 2 is
the other; allows for flexion, extension, abduction, adduction, and circumduction movement (ex: the
carpometacarpal joint in the thumb, which allows for opposable movement; only example of a
saddle joint in the human body)
Ball and socket joint: articulating surface of bone 1 is a spherical head, articulating surface of bone 2
is a cuplike socket; allows for all types of movement (ex: shoulder, hip joint)
Characteristics of synovial joints
Freely moveable (diarthrotic); allows for:
Gliding (slipping movement)
Flexion (movement decreasing the angle of the joint)
Extension (movement increasing the angle of the joint)
Abduction (movement of the limb away from the midline of the body)
Adduction (movement of the limb towards the body)
Circumduction (movement of the limb that describes a cone in space)
Rotation (movement of a bone around its axis)
Composed of articular cartilage (capping the ends of the bones), a joint cavity (space containing
synovial fluid), and an articular capsule (consisting of an outer fibrous capsule and an inner synovial
Synovial fluid: provides nutrients and oxygen to the articular cartilage; acts as a lubricant to reduce
friction as the bones move at the joint; and caps the end of the epiphysis
Hypotonic filtrate of blood in the joint cavity forms part of the synovial fluid
Outer fibrous capsule: composed of dense irregular connective tissue, hence it is highly
Reinforced by 3 types of ligaments, named based on their location in relation to the articular capsule,
providing added protection to joints
Capsular/intrinsic ligaments: located inside the fibrous capsule
Extracapsular ligaments: located external to the articular capsule
Intracapsular ligaments: located deep to the articular capsule
Menisci: discs of fibrocartilage extending from the articular capsule into the synovial cavity; improving the
fit of synovial joints and thus reducing wear and tear on the joint Chapter 8: Articulations (Joints) 10/28/2013
Bursae: flattened fibrous sacs that contain synovial fluid to reduce friction where bones, tendons,
ligaments, and muscles rub together
Tendon sheaths: elongated bursae that wrap completely around tendons subjected to a lot of friction in
order to reduce friction
Arthritis: a disease characterized by inflammation of synovial membranes that causes stiff and
painful joints Chapter 9: The Muscular System 10/28/2013
The 3 organ system of interest is the muscular system, which is composed of organs called
muscles (muscle tissue and connective tissue wrappings). There are 3 types of muscle tissue, and
therefore 3 types of muscle.
Skeletal muscle tissue: striations; long, cylindrical cells called muscle fibers; multinucleate cells
Cardiac muscle tissue: striations; branching cells with intercalated discs; uninucleate cells
Smooth muscle tissue: no striations (hence, “smooth” appearance); spindleshaped cells;
Skeletal muscle (the organ): attaches to a skeletal system (bones/cartilage); function is contraction
(which occurs at the cellular level, which makes up skeletal fibers)
Each muscle fiber is wrapped in a delicate connective tissue membrane called an endomysium. Groups
of wrapped fibers are wrapped in a coarse connective tissue membrane called the perimysium, forming
fascicles. Groups of fascicles are wrapped in a tough connective tissue membrane called the
epimysium, forming skeletal muscle.
Arrangement of fascicles in skeletal muscle
Muscle fibers in a single fascicle are parallel, but fascicles can be arranged to form parallel, convergent,
pennate, and circular muscles.
Parallel muscles: fascicles are parallel to the long axis of the muscle; most common. During
contraction, they get shorter and wider by 3050%, and the entire muscle shortens by the same amount.
Convergent muscles: muscle fibers are spread over a broad area, but converge at a common site.
These are versatile because stimulation of one part of the muscle can change the direction of pull, hence,
they pull in different directions.
Pennate muscles: fascicles form a common angle with the tendon, so muscle pulls at an angle.
Tendons do not move as far as parallel muscles do, but they contain more fibers and thus produce more
Pennate muscles are unipennate if all fibers are on the same side of the tendon, bipennate is muscle fibers
on both sides of the tendon, and multipennate if the tendon branches within the muscle.
Circular muscles: (sphincters) fascicles are arranges in concentric rings and surround external body
Attachment sites for each skeletal muscle
Skeletal muscles span joints and have 2 attachment sites:
Origin: the bone that does not move during contraction (immovable bone)
Insertion: the bone that moves during contraction (movable bone)
Skeletal muscle attaches either directly or indirectly to the bone
Direct attachment: epimysium covering the skeletal muscle attaches directly to the periosteum of the bone
Indirect attachment: epimysium is extended by a tendon, which then attaches to the periosteum. Indirect
attachments are more advantageous because: Chapter 9: The Muscular System 10/28/2013
Skeletal muscle does not contact the rough surface of the bone, only the tendons do
Tendons occupy only a fraction of the surface of the bone, allowing for more skeletal muscles to attach to
the bone for more movement regulation
Indirect attachments allow for bones to act as levers when the muscle contracts
Structure of a skeletal muscle (microscopic anatomy of a skeletal muscle fiber)
Myofibrils: rodlike structures composed of filaments called myofilaments (thick and thin) that run the
entire length of the muscle fiber (80% of the skeletal muscle fiber)
Thick filaments: ~16 nm; composed of at least 300 molecules of a protein called myosin; a rodlike
tail with 2 globular heads, each having 2 binding sites (one for actin and one for ATP) and containing
ATPase, which splits ATP into ADP and Pi; forms the A band in a sarcomere)
Thin filaments: ~8 nm; composed of the 3 proteins actin, tropomyosin, and troponin
Actin is the structural framework for the thin filaments, and contains binding sites for the myosin globular
Tropomyosin is rodlike and spirals around actin, blocking the sites for the myosin globular heads, in a
relaxed skeletal muscle.
Troponin is a tricomplex protein with TnC (which binds to calcium ions), TnT (which binds to
tropomyosin), and TnI (inhibitory; which binds to actin)
Arrangement of myofilaments in a myofibril
Thick filaments alternate with thin filaments, giving the skeletal muscle tissue a banded (striated)
appearance. In a relaxed skeletal muscle, the overlap between thick and thin filaments is incomplete. The
thin filaments are anchored by a disclike protein called the zdisc. The distance between 2 zdiscs is
called a sarcomere.
The sarcomere: the structural unit of skeletal muscle that repeat throughout the entire myofibril. Since it
is the smallest contractile unit of skeletal muscle, it is also known as the functional unit of skeletal muscle.
The structure goes as follows:
The center of the sarcomere is composed of thick filaments called A bands.
Thin filaments are anchored by the 2 zdiscs, forming an incomplete overlap of the thick and thin fibers.
The region of the thin filament not overlapping with the A bands is called the I band.
The region of the A band not overlapping with thin filaments is called the H zone (middle of the
The line that bisects and anchors the A bands is called the M line.
Myoglobin: a red pigment that binds, releases, and stores oxygen required for the aerobic catabolism of
glucose (hence why there is also mitochondria, which is responsible for aerobic respiration to produce
Inclusions: glycosomes containing glycogen
Sarcoplasm: the cytoplasm of the muscle fiber Chapter 9: The Muscular System 10/28/2013
Sarcoplasmic reticulum (SR): a specialized smooth ER that stores and releases calcium (which is
needed for muscle contraction) into the sarcoplasm. Each SR has 2 expanded ends called terminal
Sarcolemma: the plasma membrane of the skeletal muscle fiber; contains deep involutions into the
sarcoplasm called transverse tubules. Each ttubule passes through 2 terminal cisternae (of 2 SR) to
form a triad:
Structure of a triad: terminal cisterna + ttubule + terminal cisterna
Function of a triad: release of calcium ions into the sarcoplasm when the sarcolemma depolarizes – when
an action potential travels into the ttubule of the triad, calcium is released from the terminal cisternae.
Skeletal muscle contraction: when sarcomeres shorten, the myofibrils shorten too, since the sarcomeres
run the entire length of the myofibrils. When the myofibrils shorten, the skeletal muscle fibers shorten too,
since the myofibrils run the entire length of the skeletal muscle fibers. When the skeletal muscle fibers
shorten, the entire skeletal muscle shortens too, since the skeletal muscle fibers run the entire length of the
skeletal muscle organ.
The sliding filament mechanism: the sliding of thin filaments past the A bands (thick filaments) that
results in muscle contraction, because of the increased overlap between the filaments. Thin filaments are
pulled in towards the M line of the sarcomere.
The sliding of the thin filaments pulls the zdiscs inward, decreasing the distance between 2 zdiscs, thus
shortening the sarcomeres.
The H zone decreases or disappears, the I bands decrease or disappear, and the A bands remain the
Excitationcontraction coupling: the cause of the sliding filament mechanism; a series of events
which involve the activation or excitation of a motor neuron supplying a skeletal muscle that results in the
contraction of a skeletal muscle.
Motor neurons (part of the somatic nervous system) conduct impulses to skeletal muscles. They make
contact with skeletal muscle fibers via the axon terminals. Each axonal terminal innervates one muscle
fiber to form the neuromuscular junction, which comes in contact with the motor end plate, a