Histology

Question 1

Explain the 3 kinds of cartilage

Answer 1

Hyaline Cartilage with type 2 collagen and aggrecan. Uniform can’t see collagen fibers in stain
Ex. Rib cage, nose, upper respiratory tract, articular ends

Elastic Cartilage: type 2 cartilage, aggrecan, and darker elastic fibers. Can see collagen fibers in stain.
Ex. Epiglottis, external ear

Fibrocartilage: Type 1 and 2 collagen. Has isolated isogenous groups arrange axially.
Ex. IV discs, pubic symphysis, meniscus

Question 2

What are the two kinds of chondrogenesis and bone growth?

Answer 2

Interstitial growth- from inside going out.

Appositional growth- at periphery of cartilage or deep layer of perichondrium.

Question 3

What limits adult repair of cartilage?

Answer 3

Avascularity, low metabolic rate, immobility of chondrocytes.

Question 4

Explain cartilage calcification

Answer 4

NOT OSSIFICATION

CaPO4 accumulates in ECM which forms crystals and stiffens the structure.

Question 5

What are the layers of the periosteum?

Answer 5

Fibrous layer: dense irregular CT
Cellular layer- has osteoprogenitor cells actively growing
Perforating (sharply) fibers: Penetration of periosteum to underlying bone. Most at base of tendons.

Question 6

What are the two organizations of bone tissue?

Answer 6

Compact: Dense outer layer
Cancellous: Interior spongy trabeculae.

Question 7

Explain the endosteum

Answer 7

Single layer of CT with osteoprogenitor cells.

Question 8

Explain Woven vs Lamellar organization of bone building

Answer 8

No organization very loose and first to be made.

Well organized lamellar layers.

Question 9

Explain Endochondral ossification from birth on

Answer 9

Lengthening of bones by interstitial growth at the epiphyseal plate. Shaft ossified first and then secondary ossification happens at epiphyses. Leaves growth plate (zone of proliferation from reserve cartilage, zone of hypertrophy, zone of calcified cartilage, zone of ossification). Growth ends with ossification of epiphyseal plate.

Question 10

Explain appositional bone growth.

Answer 10

Growth goes from the inside out. There is bone growth going out as there is resorption on the interior.

Problems can caused thick or thin diameters of bones or even reduce medullary cavity. (See slides for questions)

Question 11

Where is the newest part of the osteon

Where is the newest part of the trabechulae?

Answer 11

The inside

The outside

Question 12

Synarthoses vs Diarthoses

Answer 12

Immobile vs mobile

Question 13

What are the stages of bone fracturerepair?

Answer 13

Hematoma stage: release of blood from broken vessels

Pro-callus stage: Macrophages remove hematoma and it is replaced by
fibrocartilage like mass.

Bony callus stage: blood vessels invade and replace fibrocartilage with woven bone.

Remodeling stage: woven bone changed to lamellar bone of the compact and cancellous bone.

Question 14

Explain skeletal Myofiber Formation

Answer 14

Myoblasts come from embryonic mesenchyme tissue derived from PARAXIAL mesoderm.

Multiple myoblasts fuse and differentiate to form a single muscle fiber (myofiber)

Unfused myoblasts cells become satellite cells which proliferate and give rise to new myofibers following injuries

Question 15

What are Leiomyomas

Answer 15

Benign tumors that develop from smooth muscle myofibers that typically don’t cause problems.

(In the uterine wall, they are called fibroids)

Question 16

Define:
Muscle Tendon unit
Motor unit
Myocyte/myofiber
Myofibril is
Sarcomere
Sarcolemma
Sarcoplasmic reticulum

Answer 16

Muscle belly and it’s tendinous attachments.

One somatic efferent neuron and all of the myofibers that it innervates.

Myocyte: one muscle cell/fiber

Myofibril: bundle of interacting contractile filaments (thick and thin) within the myofiber

Functional contractile unit of myofibril

Plasma membrane of myocyte

Endoplasmic reticulum of a myocyte

Question 17

What CT surrounds the:
Muscle Belly?
Fascicles?
Myofibers?

Answer 17

Epimysium
Perimysium
Endomysium

Question 18

What is the triad of myofibrils?

Answer 18

They encircle each myofibril and are made up of T-tubules and terminal cisternae of SR.

Question 19

What does each zone and band of the myofiber organization contain?

Explain function of a-actinin, Desmin, and dystrophin

Answer 19

Z disc: connectin filamints, Titin filaments.
I band: Titin filament, thin filament
M Line Thick filament
H zone: Thick filament
A band: Thick and thin filaments

A-actin: attaches thin filament to Z-line
Desmin: attaches z disc to another z disc or T-tubules.
Dystrophin: attaches F-actin near the periphery to the external laminate.

Question 20

Which bands decrease or increase in size?

Answer 20

A band: stays the same.

I band and H zone decrease in width.

Question 21

Myasthenia gravis

Answer 21

Autoimmune disorder involving antibodies against the proteins of the ACh receptors. Extraocular muscle are commonly the first to be affected.

Question 22

What is the difference between Duchenne muscular dystrophy and Becker muscular dystrophy?

Answer 22

Duchenne is mutation in dystrophin gene that leads to defective linkage between the cytoskeleton and ECM. Presents 3-5 yrs EARLY!

Becker is different mutation of dystrophin that is similar to Duchenne , but presents later between 17-20 years of age.

Question 23

Explain Spinal muscular atrophy

Answer 23

Gene mutation that encodes for the survival motor neuron protein that is required for survival of the somatic spinal motor neurons

Question 24

Explain Golgi tendon organs

Explain muscle spindles

Answer 24

Golgi tendon organs are in myotendinous junction.

Encapsulated after end nerve endings (somatic)

Excessive tension initiates an inhibitory reflex of the muscle activity.

Muscle spindles: encapsulated intrafusal myofibers with somatic efferent and afforestation nerve endings.

Detect change in length of the intrafusal fibers
Detect rate of length change (velocity)

Sensory information in CNS allows it to modulate the muscle activity and determine the relative positions of trunk and appendages.

Question 25

Look at the SLIDES FOR IMAGES

Answer 25

IMAGES HAHA