BT Conference: Cartilage, Bone, & Muscle

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Osteoblast (found on bone surfaces)

Cells that secrete bone matrix.

-Hyaline cartilage -Section from the larynx

Identify the tissue shown in the image. Any ideas where it could be found?

Muscle cells (Contain contractile elements called myofilaments and numerous mitchondria)

Specialized for contraction and act together to facilitate movement of the body and of substance within the body.

flesh or muscle

prefix sarco- means....

sarcolemma

Muscle cell membrane

sarcosomes

Muscle cell mitochondria

Endochondral ossification

-Involves mesenchyme developing into a cartilaginous model of the bone, then the model being replaced with bone tissue. This occurs as the cartilage continues to grow in size.

H band (bisected by the M-line)

A lighter stripe within the A-band where thin filaments are NOT present.

Spongy Bone

Bone containing large, open spaces filled with bone marrow and thin plates of bone tissue called trabeculae.

epiphyseal plate

Cartilage found at the ends of bones to allow the bone to grow in length until the final adult size is reached.

Intercalated discs

Connect adjacent cardiac muscle cells and contain desmosomes and fasciae adherentes to bind cells together and gaps junctions to facilitate communication among cells. They appear as darkly stained lines between cells using light microscopy.

Osteons (aka Haversian systems)

Cylinders of concentric lamellae (layers) of bone

Osteoclasts

Degrade and remove martrix

-Hard due to high concentration of minerals (mostly hydroxyapatite crystals) -Contain significant amount of inorganic matter (Ca, P, Mg, K)

Describe the ECM of bone.

-CT = non-cartilaginous connective tissue -F = Fibrous layer of the perichondrium -Cg = Chondrogenic layer of the perichondrium (nuclei here belong to chondrogenic cells and chondroblasts) -C = Chondrocytes, which are surrounded by the extracellular matrix.

Describe the components shown in the image of hyaline cartilage from the trachea.

-ECM contains collagen type II fibers -Fibers are very small, cannot see with light microscopy so appears smooth and glassy -Rich in GAGs and proteoglycans

Describe the matrix of hyaline cartilage.

-Compared to mature bone, woven bone has more cells, a more irregular arrangement of collagen fibers, and less mineralization. -Lamellar bone has a very organized matrix: the tissue is arranged in lamellae (flat sheets).

Describe woven and lamellar bone.

-No, because the myofilaments are not organized into myofibrils ***When the muscle contracts the nuclei can appear twisted like a corkscrew

Does smooth muscle appear to be striated?

Muscles

Fascicles are bound together to form _______.

Myofibrils

Fills most of the skeletal muscle cell

Intramembranous ossification

Formation of the bone directly from mesenchyme, without a cartilagenous model.

-osteoprogenitor cells -osteoblasts -osteocytes -osteoclasts

Four types of bone cells?

parallel

Haversian canals run ________ to the long axis of the bone and contain blood vessels.

-Both have a perichondrium, chrondrocytes (often in isogenous groups) found in lacunae, and Type II collagen fibrils in matrix -However, elastic cartilage has elastic fibers

How are hyaline and elastic cartilage similar and different?

-Appositionally (through division of cells in the inner perichondrium) -Interstitially (though division of chondrocytes to form isogenous groups).

How can cartilage grow?

-gap junctions between long cellular processes off of the osteocyte

How do osteocytes communicate?

-Section of Compact bone -A = Osteocytes -B = Cannaliculus -C = Haversian Canal -D = Osteon

Identify the tissue shown and the ID the A-D.

-Hyaline cartilage found in the trachea ***Note the pseudostratified epithelium and presence of cilia to indicate the trachea

Identify the tissue shown in the image. Any idea where it could be found?

-Elastic cartilage -Section form the external ear

Identify the tissue shown in the image. Any ideas where it could be found?

-Section of compact bone -Osteon (Os)- roughly circular in cross-section

Identify the tissue shown in the image. What does Os mean in this image?

-Elastic Cartilage from the epiglottis -Can also be found in the external ear and pharyngotympanic tube

Identify the tissue shown in the image. Where could it be found?

-Fibrocartilage -It can be found in the pubic symphysis, the intervertebral discs, and the temporomandibular joint.

Identify the tissue shown in the image. Where could it be found?

-Compact and spongy bone -Longitudinal section through the end of a long bone

Identify the tissue shown in the image. Where could it have been taken from?

-Spongy Bone -Lamellar bone, but the lamellae are not arranged in osteons and there are NO blood vessels within the bone tissue ***trabeculae are surrounded by white adipose tissue

Identify the tissue shown in this image. Is it woven or lamellar?

A trabecula of woven bone in the prenatal skull

Identify this tissue.

-A = Myosin -B = Actin

In skeletal and cardiac muscle, thick filaments (made of _____A_____) and thin filaments (made of ______B_____) are arranged in a manner that gives the appearance of alternating light and dark stripes.

Cardiac Muscle

Involuntary, striated muscle found in the heart, innervated by the ANS. Cells contain one centrally placed nucleus.

sarcoplasmic reticulum

Muscle cell ER

sarcoplasm

Muscle cell cytoplasm

Smooth Muscle

Muscle tissue found in viscera other than the heart and is involuntary. Cells are spindle shaped (fusiform)) and can be connected to one another via gap junctions.

Myofilaments

Myofibrils contain _________, which create a banding pattern (striations) that can be seen histologcially.

Haversian canal

Name for tunnel surrounded by osteons?

Woven bone (aka primary bone)

Newly formed bone

Sarcomere

Nice image

Osteocytes (found within the bone itself)

Once osteoblasts completely surround themselves with the matrix they are called...

monocytes

Osteoclasts are derived from ________ and are large and multinucleated

Osteoprogenitor cells

Stem cells that can give rise to osteoblasts under certain conditions

TRUE

T/F: Both spongy and compact bone are originally formed as woven bone, then are replaced by lamellar bone.

TRUE

T/F: Cartilage is avascular and gasses and nutrients must reach the inner parts of the tissue by diffusion.

FALSE, fibrocartilage has no perichondrium and is more of a transition between dense connective tissue and hyaline cartilage.

T/F: Fibrocartilage is surrounded by perichondrium.

TRUE

T/F: In the walls of many organs, there are two layers of smooth muscle, one running in a circle around the lumen and one running longitudinally along the long axis of the organ. There can be a parasympathetic ganglion positioned between the layers.

False

T/F: Spongy bone contains osteons.

TRUE

T/F: The trabeculae of spsongy bone do not contain blood vessels and the lamellae are NOT organized into osteons.

TRUE

T/F: When a muscle contracts the thin and thick filaments alide relative to one another bringing the Z-discs closer together. This will make the I and H bands shorter, but will NOT change the A band length.

-A = A-band -B = I-band (thin filaments and NO thick ones) -C = Z-disc

The dark stripe is called the ______A______ and the light stripe is called the _______B______. At higher magnifications, you can see that the I band has a darker stripe in the middle of it. This is known as the _______C_______.

Skeletal muscle

The diaphragm is largely made up of which type of tissue?

Sarcomere (area between to adjacent Z-discs)

The structural and functional units myofibrils are organized into...

Volkmann's canals, which run perpendicularly to the Haversian Canals

The vessels within Haversian canals are connected to one another via vessels running in ___________

smooth muscle

The wall of the small intestine is largely made up of which type of tissue?

Fascicles

Thick bundles of muscle fibers bound together

-Intramembranous ossification -Endochondral ossification

Two ways in which bone can be formed?

Skeletal, smooth, and cardiac

Three types of muscles

-Spongy (cancellous, trabecular) -Dense (compact, cortical)

Types of bone tissue?

Compact Bone

Very dense bone containing a network of blood vessels running through it. It is lined by connective tissues.

Skeletal muscle fibers

Voluntary muscle fibers that are cylindrical in shape and are found attached to bones and cartilage. They are multinucleated, with the nuclei being located in the periphery of the cell.

Compact bone

What always surrounds spongy bone?

Muscle fibers, because tend to be long and narrow

What are muscle cell aka and why?

-Cardiac muscle cells that are specialized for conduction and are located just deep to the endocardium. Compared to typical cardiac muscle fibers, they are larger and paler. They have fewer myofibrils and more glycogen.

What are purkinje fibers?

-Asterisk = Osteoblast almost surrounded by matrix, will soon become an osteocyte -Arrow = Howship's Lacuna, where osteoclast sits as it resorbs the woven bone and replaces it lamellar bone. -Matrix is pink and surrounding mesenchyme is white.

What are the asterisk and arrow heads indicating?

-Outer fibrous layer, consisting of collagen fibers and fibroblasts. -Inner layer (aka chondrogenic layer), which consists of chondrogenic cells (give rise to chondroblasts).

What are the two layers of the perichondrium?

-Mostly bones of the skull -Ossification of the shaft of long bones

What bones form via intramembranous ossification?

-Periosteum - has an outer fibrous layer and an inner cellular layer, which contains osteoprogenitor cells and osteoblasts. Adjacent to the outer circumferential lamellae. -Endosteum - also contains osteoprogenitor cells and osteoblasts. Adjacent to the inner circumferential lamellae.

What connective tissues lines compact bone?

-A = The parallel rows of chondrocytes, between bundles of collagen. -B = Type I collagen bundles (Type II also found in this cartilage). Type I bundles make the matrix more acidophilic and provide tensile strength

What do the arrows at A and B point to in the image of fibrocartilage?

-Os = osteon -HC = Haversian Canals -VC = Volkmann's Canals -L = Lamellae of the osten -IL = interstitial lamellae

What do the letter stand for in the image of compact bone?

-The perichondrium, which is a layer of dense irregular connective tissue. -Perichondrium surrounds hyaline and elastic cartilage

What does A indicate in the image?

-Isogenous group - when chondroblasts secrete matrix they surround themselves in it and become trapped in lacunae (matrix spaces). Eventually they become less active and are called chondrocytes, these can divide a limited number of times in growing cartilage. Daughter cells that remain close together in lacunae are called an isogenous group.

What does the arrow from B indicate? Describe.

-Bone being formed via enchondral ossification -CC = trabeculae of calcified cartilage -Covered by woven bone (arrow), which stains a darker pink and contain osteocytes -Osteoblasts (Ob) line the surface of the bone and secrete osteoid (Ot), whcih will be calcified to become bone matrix

What does the image show?

-A = Compact bone surrounding the spongy bone -Arrows = The many trabeculae of spongy bone (space filled with adipose tissue). ***This is adult lamellar bone, but since at a low mag. cannot see the lamellae

What is being indicated by the letter A and the arrows in the image?

The boundary of an osteon called the cement line

What is located between the arrowheads?

-Bone being formed via intramembranous ossification -Osteoblasts (Ob) are differentiating from the mesenchymal cells (arrows). Osteoblasts secrete osteoid (Ot) which will calcify and become bone matrix. -Oc = osteocytes, results when Ob surround themselves with bone matrix.

What is shown in the image?

-Section of an epiphyseal plate of developing long bone -ZP = Zoe of proliferation; resting cartilage would be located superior this zone -ZH = Zone of Hypertrophy -ZC = Zone of Calcifying cartilage. Inferior to this zone is the zone of ossification -Asterisks = spicules of calcified cartilage

What is shown in the image?

-Elastic fibers -It is only visible due to special stains otherwise look like hyaline cartilage -Elastic fibers provide elasticity to the cartilage

What is the arrow pointing at and its significance?

Endomysium

What is the layer of wispy, loose areolar CT surrounding individual muscle fibers?

- Here, osteoblasts deposit bone on the spicules of calcified cartilage and the calcified cartilage will eventually be replaced by bone.

What occurs at the zone of ossification?

Titin

What protein connects the thick filament to the Z disc?

Lamellar bone (aka secondary bone or mature bone)

What replaces woven bone?

Perimysium, which is dense irregular collagenous CT

What surrounds fascicles?

-Epimysium, which is dense irregular collagenous CT

What surrounds muscles?

Longitudinal section through skeletal muscle. -Muscle fibers run horizontally to each other and each muscle fiber is striated (faint vertical stripes)

What tissue is shown in the image?

-Cardiac muscle (electron micrograph) -Numerous mitochondria (m), myofibrils (M), and Z discs (Z). The nucleus (N) is in the center of the cell, not adjacent to the sarcolemma (Sl) -Inset box = intercalated disc, with its transverse portion (asterisk) and longitudinal portion (arrows).