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Exam 2 Flashcards

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1
Q

General characteristics of cartilage

A

Avascular connective tissue
Typically found in areas of support (weight-bearing) and movement
Contains chondrocytes and matrix
3 subtypes - Hyalin, elastic, fibrous

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2
Q

Chondrocytes

A

Large rounded cells with light cytoplasm and small nucleus
Produce matrix
Inactive
Function in lipid and glycogen storage

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3
Q

Composition of cartilage matrix

A

Firm, high in glycosaminoglycans (GAG), and hyaluronic acid

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4
Q

Hyalin cartilage

A

Binds bones together (i.e. in synchondrosis)
- Low friction surfaces for joints
Model for developing skeleton of the fetus (endochondral ossification) - much of the cartilage is replaced by bone, while remaining cartilage forms the epiphysial growth plate
- Matrix - firm, glassy with mostly Type II fibers

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5
Q

Why isn’t collagen detectable with H&E staining in hyaline cartilage?

A

It is present in the form of fibrils, and its refractive index is the same as the ground substance

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6
Q

What are the cavities in the matrix called?

A

Lacunae, which contain chondrocytes

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7
Q

Chondroblasts

A

Originate from mesenchymal cells
Basophilic cytoplasm, synthesize the cellular matrix
Do not aggregate into clusters
Located in growing cartilage

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8
Q

Isogenous groups

A

Recently divided chondrocytes are sitting in clusters in the lacunae

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9
Q

Territorial Matrix

A

Basophilic “capsule” around isogenous groups - high concentration of Glycosaminoglycans

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10
Q

Interterritorial matrix

A

Lighter matrix around the territorial matrix

- low concentration of Glycosaminoglycans

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11
Q

Perichondrium

A

Collagenous membrane on the surface of the cartilage
Carries vessels and nerves essential for the avascular cartilage
- destruction of perichondrium usually results in destruction of underlying cartilage

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12
Q

What two layers are found in perichondrium?

A

An outer fibrous layer of dense connective tissue

An inner chondrogenic layer - contains mesenchymal cells, source of chondrobalsts

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13
Q

When is perichondrium not present?

A

When the cartilage contacts with bone

Articular surfaces

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14
Q

Elastic cartilage

A

Contains elastic fibers in the matrix in addition to ground substance
Stains with resorcin-fuchsin or orcein
Elastic properties - ear, cartilages of the larynx
Does not calcify with aging Unlike hyaline cartilage)

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15
Q

Fibrocartilage

A

Combination of dense regular connective tissue and hyaline cartilage
Chondrocytes are sitting in rows - isogenous groups
Large amount of collagen fibers between them
- No perichondrium
- Like a tendon, but instead of fibroblasts there are cartilage cells

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16
Q

Appositional growth

A

A type of cartilage growth
Chondroblasts are formed by the inner layer of perichondrium - cells produce collagen type I
These produce matrix (collagen type II) and turn into chondrocytes

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17
Q

Interstitial growth

A

A type of cartilage growth

Division of chondryctes within the lacunae, forming isogenous groups

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18
Q

Cartilage growth and repair

A

Appositional and interstitial growth
Very limited repair - avascular tissue, dependent on the perichondrium
Hyaline cartilage often calcifies (is replaced by bone)

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19
Q

General characteristics of bone

A

Connective tissue characterized by a mineralized extracellular matrix
Functions - support, proteciton, storage site for calcium and phosphate

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20
Q

What does bone extracellular matrix consist of?

A

Hydroxyapatite crystals
Collagen type I, small amount of collagen V
Glycoproteins - osteocalcin, osteoectin, osteopontin

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21
Q

What are the histological components of bone?

A

Bone tissue
Hemopoietic tissue (i.e. red marrow in the epiphysis)
Fat tissue (yellow bone marrow at the shaft)
Dense connective tissue - outer fibrous layer of periosteum - Sharpey’s fibers extend into bone)
Vessels and nerves
Endosteum - covers the inner surface of the marrow cavity - osteoprogenitor or endosteal cells that differentiate into osteocytes

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22
Q

Haversian lamellae

A

Concentrical lamellae surrounding the haversian canal forming cylindrical units called Osteon or Haversian systems - axis is usually parallele with the shaft
Haversian canals contain vessels and nerves
- Connected by Volkmann’s canal
Lacunae between lamellae with osteocytes
Canaliculi penetrate lamellae with osteocytic processes

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23
Q

Interstitial lamellae

A

Between the osteon space is filled with old Haversian systems

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24
Q

Outer circumferential lamellae

A

Line the outer surface of the bone under the periosteum

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25
Inner circumferential lamellae
Lining the inner surface of the bone under the endosteum
26
Immature bone
- In the skeleton of the developing fetus, adult alveolar sockets, tendon attachments - nonlamellar (woven) bone - interlacing collagen fibers - more cell-rich than mature bone - cells tend to be randomly arranged - matrix is less mineralized and has more ground substance than bone - thus, it stains more basophilic
27
Periosteum
Collagenous membrane on the outer surface of the bone - carries vessels and nervs, contains nociceptors 2 layers - outer fibrous layer and inner osteogenic layer
28
Endosteum
Membrane covering the marrow cavity | Composed mostly of osteoprogenitor cells
29
Osteoprogenitor cells
Flattened cells that resemble fibroblasts Basophilic cytoplasm Location - inner layer of periosteum, endosteum (endosteal cells), line the haversian and volkmann's canals Capable to divide and differentiate into osteoblasts Also can form chondroblasts, adipocytes, fibroblasts Participate in appositional bone formation
30
Osteoblasts
Secretory cells capable of division Secretes collagen and ground substance that forms the initial unmineralized bone, the osteoid (light staining vs. eosinophilic calcified bone tissue) When surrounded by osteoid - called osteocyte Basophilic cytoplasm - lots of rER For a single cuboidal cell layer on the surface of the growing bone, sitting on a light band of osteoid
31
How is the calcification process initiated by osteoblasts?
Osteoblasts secrete vesicles containing alkaline phosphatase
32
Osteocytes
Completely surrounded by osteoid or mineralized bone (lacunae) Maintains the matrix - secretes/reabsorbs - death of osteocyte results in reabsorption of bone - Elongated cells with numerous processes (spider shape) Processes communicate with the neighboring cells by gap junctions and occupy the canaliculi
33
What do canaliculi do?
Connect lacunae
34
Types of osteocytes
Inactive (quiescent) - few organelles Formative osteocytees - rER Resorptive osteocytes - lysosomes
35
Osteoclasts
Large, multinucleated acidophilic cells responsible for bone resorption Originate from the monocytes (macrophages) of blood Nuclei are sitting on the side of the cells farther away from the bony trabecula - surface contacting bone forms membrane infoldings - ruffled border
36
What is a Howship's lacuna?
Resorption bay for osteoclast, where it rests when it's not active
37
How does the osteoclast resorb bone?
Probably releases organic acids (i.e. carbonic acid?) that decalcify the underlying bone - releases lysosomal hydrolases that digest organic components
38
What hormones regulate osteoclast activity?
``` Parathyroid hormone (PTH) increases osteoclast activity - calcitonin decreases osteoclast activity ```
39
Intramembranous ossification
Mesenchymal cells aggregate and turn into osteoblasts - osteoblasts secrete osteoid, mineralize it, enclose themselves in lacunae, and turn into osteocytes - occurs in embryo skull bones and in fractures when the broken ends are very closely aligned to each other
40
Endochondral ossification
Everything starts with a hyaline cartilage model of the bone - perichondrium forms a bony collar around the cartilage model (appositional growth) - periosteum Primary ossification center develops - chondrocytes in the middle of the model become hypertrophic, secrete alkaline phosphatase, and surrounding matrix undergoes ossification - the calcified matrix inhibits diffusion of nutrients - apoptosis - death of chondrocytes - matrix breaks down, forming a cavity
41
What are the layers of enchondral ossification?
Zone of reserve cartilage Zone of proliferation - cartilage cells are arranged into rows Zone of hypertrophy Zone of calcified cartialge Zone of resorption - resorption of dead chondrocytes
42
Golgi Stain
- Developed by Camillo Golgi - Uses silver precipitation - once a grain of silver attaches to a neuron, the rest of the neuron plates out entirely faster than the next neuron - Only about 5% of the neurons are stained, which enables us to see their structure
43
What are the 3 predominant types of cells in the nervous system?
Neurons Neuroglia Blood vessel cells
44
Neurons
- Conducting cells specialized to conduct electrical activity - Sensory neurons - somatic or visceral afferent - Motor neurons - somatic or visceral efferent - Interneurons - communication between sensory and motor neurons (most neurons are interneurons) - Terminally differentiated - rarely become cancerous
45
Neuroglia
Supporting cells, nonconducting Provide physical and metabolic support, electrical insulaiton, surface of the brain and ventricles, can divide and thus can become cancerous
46
Multipolar Neurons
``` Multiple poles (dendrites) coming out of the cell body Most cells are multipolar ```
47
Bipolar Neurons
2 poles coming out of cell body - dendrite and axon Sensory Found in retina, cochlear and vestibular ganglia
48
Pseudounipolar Neurons
One branch coming off of cell body, but still has an axon and a dendrite Sensory Found in spinal and most cranial sensory ganglia
49
What type of cells reside in the dorsal root ganglion?
Pseudounipolar sensory cells
50
Types of multipolar cells
``` Cell body size can range from 4 to 150 micrometers Motor PNS - Spinal and motor Integrative PNS - Pyramidal - Granule Cells Cerebellar purkinje cells ```
51
What are the cortical layers?
1. Molecular layer 2. External granular layer 3. External pyramidal cell layer 4. Internal granular layer 5. Ganglionic layer (internal pyramidal cells) 6. Multiform (polymorphic) cell layer
52
Purkinje cells
Primarily involved in motor coordination
53
Histologically, how are neurons different from neuroglia?
Much larger Nucleus is large, lightly stained (euchromatic) with a prominent nucleolus Perinuclear cytoplasm shows Nissl bodies (rER, ribosomes, high level of metabolism) and axon hillock - are where axon is just forming outside of cell body
54
Glia
Glia means glue; supporting cells of nervous system PNS - schwann cells, satellite cells CNS - oligodendroglia, astrocytes, microglia, ependyma
55
Schwann cells
Found in peripheral nervous system | Same function as oligodendrocytes - provide the myelin found on peripheral nervous system nerves
56
Satellite cells
Surround neuron cell bodies of spinal ganglia Found in peripheral nervous system Function - electrical and metabolic insulation (controlled microenvironment)
57
Oligodendroglia
Found in central nervous system Same function as Schwann cells: provide myelin found on neurons (in CNS) Responsible for the "white matter" of CNS
58
Astrocytes
``` Star-shaped cells Form blood-brain barrier Most numerous of the glial cells some have "end feet" Contain GFAP (easily stained protein) 2 types: Fibrous type in white matter, protoplasmic type found in gray matter ```
59
Microglia
Smallest of the glia Phagocytic cells Derived from bone marrow (not neural tube like all the others)
60
Ependyma
Line the ventricles and central canal | Appear cuboidal or columnar
61
Myelin Sheath
Formed by Schwann cells in PNS and Oligodendrocytes in CNS Function - electrically isolates axon from the surroundings Composed of multiple layers of cell membrane wrapped around the axon
62
Dendrites
Receive Information
63
Cell body of neuron
Aka perikaryon | Gray matter and ganglia
64
Axon
Single process | Conducts signal
65
Terminal arborization
Branches, i.e. in Purkinje cells
66
End bulbs
Boutons
67
Synapses
Junctions between neurons

Histology (3 decks)

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