Anatomy Exam 3

Front 1

1) Name the 3 types of fibrous joints

Back 1

1) Sutures = short fibrous CT binding the bones

2) Syndesmoses = bones are connected by ligament , interrosseus membrane (dense regular CT) allows slight movement and ligaments connect bones to bones (synarthrotic)

3)Gomphoses = present only in jaws where short periodontic ligaments connect teeth to the alveolar sockets deep in the jaws

a. Found only in the skull – SUTURES
b. Located between teeth and the alveolar sockets – GOMPHOSES

Front 2

2) Name the 2 types of cartilaginous joints

Back 2

1) Synchondroses = hyaline cartilage binds the bone
ex. Epiphyseal plates that connect the epiphysis to the diaphysis in long bones, Costal cartilage --> connect the ribs to the manubrium of the sternum, synchondroses are synarthrotic joints (immovable)

2)Symphyses = fibrocartilage connects the bones at the joint sites
Ex.: Intervertebral discs in between the vertebrae, pubic symphysis = a pad of fibrocartilage that connects the 2 hib bones. Symphyses are amphiarthrotic joints

The epiphyseal plate is an example of what type of cartilaginous joint? SYNCHONDROSES
What type of cartilaginous joints are the intervertebral discs? SYMPHYSES

Front 3

3.Name the 6 types of synovial joints

Back 3

1) Plane joint
2) Hinge joint
3) Condyloid joint
4) Ball and socket joint
5) Saddle joint
6) Pivot joint

Front 4

Give the characteristics of the articulating surfaces at all the 6 types of synovial joints:

Back 4

1) Plane joint = both articular surface of bones are flat, movement is gliding/translational, ex. Intercarpals and intertarsals

2) Hinge joint = 1st bone is cylindrical, 2nd bone is trough shaped to articulate w/cylindrical bone surface, extension and flexion, ex. Elbow and knee joints

3) Condyloid joint = both bones are oval, first bone (protrusion) fits into depression in another, extension, flexion, abduction, adduction, circumduction , ex. Radiocarpal wrist joints and knuckle joints. Location: several such as the occpital condyles with the articular facets on the surface of the atlast --> this particular joint allows us to motion 'yes


4) Ball and Socket joint =1st bone is spherical or hemispherical, 2nd bone is cuplike , universal movement, ultimate diarthrotic joints (freely movable) , ex. Glenohumeral joint, hip joint

5) Saddle joint = 1st bone and 2nd bone have concave and convex surfaces
Ex. Carpometacarpal joints of thumb

6) Pivot joint = round end of one bone fits through a sleeve made of ligament or bone , movement is uniaxial rotation of one bone around its long axis
Ex. Atlanto-axial joint

Name the type of synovial joint that allows us to motion “no” – PIVOT JOINT (atlanto-axial joint)

Name the type of synovial joint that allows us to motion “yes” -
Give the only location in the human body for a saddle joint – carpometacarpal joint of thumb

Front 5

4.Define: menisci, bursae, tendon sheaths

Back 5

▫ Menisci = articulating discs, pads of fibrocartilage extending from the articular capsule into the joint cavity to properly fit articulating bones, reduces wear and tear of the joint and stabilize joints

▫ Bursae = flattened fibrous sacs that contain synovial fluid and are present in areas subjected to stress such as glenohumeral joint and knee joint , reduce friction!

▫ Tendon sheaths = elongated bursae, reduce friction!

Front 6

5. Describe a synovial joint.

Back 6

▫Joint cavity is present, ligaments bind and reinforce the synovial joint, all synovial joints are diarthrotic (movable) due to the presence of the joint cavity.
▫ Surface of the articulating bones are covered by a thin layer of hyaline cartilage called ARTICULAR CARTILAGE is present --> encloses the joint cavity.
▫Articular capsule is present and encloses the joint cavity
▫ Join cavity separates the articular bones which contains synovial fluid
▫ Synovial fluid acts as a lubricant to reduce friction as the bone moves at joint, contains phagocytic cells that engulf and destroy bacteria and cell debris inside the joint cavities, provides nutrients to the articular cartilage that covers the articulating bones (it’s a filtrate of blood)
▫ Articular capsule (2 layer) encloses the joint cavity
▫ Outer fibrous capsule - composed of dense irregular CT which is continuous with the periostea of the articulating bones
▫ Inner synovial membrane : composed of areolar CT over dense irregular CT...the synovial membrane secreates synovial fluid into the JOINT CAVITY
▫ Articular cartilage is hyaline cartilage that covers the articulating surface of the bones
▫Ligaments bind and reinforce the synovial joints

Front 7

Define a bunch of stuff!

Back 7

▫ Endomysium = covers each skeletal muscle or muscle fiber
▫ Perimysium = CT membrane that covers a fascicle ,
▫ Fasicle is a bundle of endomysium covered muscle fibers
▫ Epimysium covers a bundle of fascicles
▫ Tendons = cord of dense fibrous tissue attaching muscle to bone, anchors muscle to CT covering of a skeletal element or to the fascia of other muscles
▫ Sarcolemma = plasma membrane of skeletal muscle fiber
▫ Sarcoplasmic reticulum = specialized smooth ER in muscle cells/fiber, stores and release Ca+ into sarcoplasm when muscle fiber is stimulated to contract
▫ Myoglobin = red pigment found in muscle fiber that stores & release oxygen
▫ Sarcromere = smallest contractile unit of muscle fiber, structure of the sarcomere is defined by the space of the myofibril between 2 successive Z lines. (contains the A band with H zone) Also present in sarcomere are elastic filaments which anchor the thich filaments in the A bands + also allows the skeletal muscle to assume its original size after muscle contraction.
▫ Z disc = bisects and anchors the I band or thin filaments (anchors the I bands)
▫ I band = region of thin filaments not overlapping the A band
▫ A band = center region of sarcomere that contains thick filaments overlapping with thin filaments
▫ H zone = region of A band that does not overlap with thin filaments
▫ M line = dark line bisecting the H zone (Anchors the A bands)
▫ Triad = successive groupings of the three membranous structures (terminal cisternae, T tubule , terminal cisternae) (Deep invaginations (infoldings of the sarcolemma (p.m) of the muscle fiber are called Transverse tubules. A terminal cistern is the expanded end of the SR)
▫ Motor unit = composed of a motor neuron and all its skeletal muscle fibers it innervates via axon terminal

Front 8

Describe the neuromuscular junction.

Back 8

Neuromuscular junction forms between an axon terminal and motor end plate (a highly folded region of the sarcolemma of skeletal muscle fiber that provides large surface area for ACH) The gap between the axonal terminal and motor end plate is the neuromuscular cleft.
Nerve impulse reaches end of an axon, Ca+ gated channels open and allows Ca2+ to flow in from extracellular fluid. This causes some of the synaptic vesicles to fuse with axonal membrane to release Ach in the neuromuscular cleft. Ach diffuses across the cleft and attaches to Ach receptors on the sarcolemma. Results in generation of action potential at the motor end plate which travels across the entire sarcolemma and into the t-tubule.

Front 9

What is the motor end plate?

Back 9

Highly fold region of sarcolemma of muscle fiber that provides large surface area of Ach receptors.

Front 10

Name the 3 proteins in a thin filament.

What is the function of tropomyosin in relaxed skeletal muscle?

Name the 3 subunits of troponin.

Which tropnin subunit is bound to actin?

Back 10

1) actin – forms core of filament

2) tropomyosin – wraps (spirals) around actin

3) Troponin – 3 polypeptide complex (regulatory protein)

What is the function of tropomyosin in relaxed skeletal muscle?
- Blocks myosin binding sites on actin so that myosin heads cannot bind to actin

Name the 3 subunits of troponin.
- TnT: binds to tropomyosin, helps tropomyosin position on actin
- TnI: inhibitory troponin, binds to actin
- TnC : binds to calcium

Front 11

4. What are crossbridges and what are activated crossbridges?

Back 11

- Crossbridges are globular heads from tail of myosin molecule, each crossbridge has a ATP binding site (where ATPase splits ATP into energy for muscle contraction) and binding site for actin .

Activated crossbridges are crossbridges with ADP & Pi attached (ATPase hydrolyzes ATP  ADP+Pi), bind to exposed myosin binding sites on actin

Front 12

. Describe the function of myosin crossbridges in muscle contraction

Back 12

Acts as motors to generate tension developed by a contracting muscle cell. , shortening occurs when the tension generated by the cross bridges on the thin filaments exceeds the forces opposing shortening.

Front 13

6.Give the role of ATP in muscle contraction – What is rigor mortis?

Back 13

Rigor mortis = Absence of ATP – causes attachment of crossbridges and never detach causing prolonged skeletal contraction --> stiffening of dead bodies 3-4 hrs after death . Breathing ceases --> cell respiration ceases --> no ATP synthesis --> attached crossbridge CANNOT detach = rigor mortis.

Front 14

7. Define the sliding filament theory - list structures that a ) shorten b) remain the same
when a skeletal muscle contracts.

Back 14

During contraction, the thin filaments slide past the thick ones so that actin and myosin filaments overlap to a greater degree. When muscle fibers are stimulated by nervous system, the myosin heads latch onto myosin binding sites on actin in the thin filaments and sliding begins. These cross bridges attachments are formed and broken down several times acting like tiny ractchets to generate tension and propel thing filaments toward center of sarcomere (m line). The Z discs are pulled toward thick filaments, overall I bands shorten, H zone disappears and the A bands move closer together but do not change in length.

Front 15

8. Discuss the factors that affect the strength of contraction:

Back 15

- Size of motor unit , motor units with smallest muscle fibers are controlled by small highly excitable motor neurons and are activated first, goes from small –medium- large. Size principle is important because it allows increases in force during weak contractions to occur in small steps, whereas gradations in muscle force are progressively greater when large amts of force are needed for vigorous activities. More motor unites that are recruited, greater muscle force will be.
- Size or diameter of skeletal muscle fibers, larger ones generate more force for contraction (has more sarcromeres and myofibrils).
- Frequent stimulation - a rapidly stimulated skeletal muscle generates more force due to increase in calcium in the sarcoplasm as a result of summation of stimuli
- Diameter (length) of the sarcromere prior to contraction