Histology Flashcards
Explain the 3 kinds of cartilage
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
What are the two kinds of chondrogenesis and bone growth?
Interstitial growth- from inside going out.
Appositional growth- at periphery of cartilage or deep layer of perichondrium.
What limits adult repair of cartilage?
Avascularity, low metabolic rate, immobility of chondrocytes.
Explain cartilage calcification
NOT OSSIFICATION
CaPO4 accumulates in ECM which forms crystals and stiffens the structure.
What are the layers of the periosteum?
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.
What are the two organizations of bone tissue?
Compact: Dense outer layer
Cancellous: Interior spongy trabeculae.
Explain the endosteum
Single layer of CT with osteoprogenitor cells.
Explain Woven vs Lamellar organization of bone building
No organization very loose and first to be made.
Well organized lamellar layers.
Explain Endochondral ossification from birth on
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.
Explain appositional bone growth.
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)
Where is the newest part of the osteon
Where is the newest part of the trabechulae?
The inside
The outside
Synarthoses vs Diarthoses
Immobile vs mobile
What are the stages of bone fracturerepair?
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.
Explain skeletal Myofiber Formation
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
What are Leiomyomas
Benign tumors that develop from smooth muscle myofibers that typically don’t cause problems.
(In the uterine wall, they are called fibroids)
Define: Muscle Tendon unit Motor unit Myocyte/myofiber Myofibril is Sarcomere Sarcolemma Sarcoplasmic reticulum
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
What CT surrounds the:
Muscle Belly?
Fascicles?
Myofibers?
Epimysium
Perimysium
Endomysium
What is the triad of myofibrils?
They encircle each myofibril and are made up of T-tubules and terminal cisternae of SR.
What does each zone and band of the myofiber organization contain?
Explain function of a-actinin, Desmin, and dystrophin
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.
Which bands decrease or increase in size?
A band: stays the same.
I band and H zone decrease in width.
Myasthenia gravis
Autoimmune disorder involving antibodies against the proteins of the ACh receptors. Extraocular muscle are commonly the first to be affected.
What is the difference between Duchenne muscular dystrophy and Becker muscular dystrophy?
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.
Explain Spinal muscular atrophy
Gene mutation that encodes for the survival motor neuron protein that is required for survival of the somatic spinal motor neurons
Explain Golgi tendon organs
Explain muscle spindles
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.
