Histo Exam 2 Flashcards
(238 cards)
1
Q
Chondroprogenitor cells
A
Mesenchyme progenitor unipotent stem cells that differentiate into chondroblasts as part of appositional growth
2
Q
Chondroblasts
A
An immature cell that actively produce the components of the extracellular matrix and are involved in appositional growth.
3
Q
Chondrocyte
A
Are cells that secrete the extracellular matrix on cartilage and becomes embedded in it. Derived from chondroblasts, mature and involved in nourishment and maintenance of the cartilage. Involved in interstitial growth of cartilage.
4
Q
Perichondrium
A
DRCT covers the outer surface of most cartilage types. Contains and outer fibrous layer made of fibroblasts and capillaries. and an inner cellular layer that contains chondroporogenitor cells
5
Q
Blood supply of cartilage
A
Avascular. Blood vessels found in DRCT of perichondrium and nutrients must diffuse through ground substance
6
Q
Lacunae
A
Potential spaces surrounding the cells within the matrix in which they chondrocyte/chondroblast resides.
7
Q
Isogenous groups
A
Clusters of recently mitotic chondrocytes. Reflects recent mitosis of chondrocytes and interstitial growth
8
Q
What fiber type is present in all cartilage
A
Type II
9
Q
Ground substance
A
Non fibrous proteins. Hyaluronic acid, proteoglycans, glycoproteins. High amounts of ground substance draws in high amounts of water to provide turgor
10
Q
Does supportive CT or CT proper have more ground substance
A
Supportive CT like bone and cartilage has more GS
11
Q
Territorial matrix
A
Region immediately surrounding lacunae with newly synthesized matrix proteins. Contains a higher amount of ECM.
12
Q
Inter-territorial matrix
A
A region of older cartilage matrix proteins located between the lacunae. Stains lighter than territorial matrix.
13
Q
What are the three types of cartilage
A
Hyaline, elastic, and fibrocartilage.
14
Q
Hyaline cartilage
A
Type II collagen, perichondrium usually present but not on articular surface of synovial joints. Resists compressive forces/flexible support of respiratory system. Provides smooth low friction surface. Located in costal cartilage, trachea, nasal cartilage, articular joint surfaces.
15
Q
What provides nutrients to synovial joints
A
The synovial membrane that produces the synovial fluid since there is no perichondrium.
16
Q
Elastic cartilage
A
Always has a perichondrium, provides flexible support and elasticity and found in the pinna, external auditory canal, epiglottis, larynx
17
Q
Fibrocartilage
A
Type I and II collagen, never has a perichondrium. Type I collagen fibers between rows of cells. Always associated with DRCT and provides tensile strength and resilience for DRCT. Provides protection against compressive, tearing and shearing forces, cushioning, resists deformation and shock absorption. Intervertebral discs (annulus fibrosus), meniscus of knee, covers articulating surface of condyle, articular disc.
18
Q
Interstitial growth
A
Mitotic division of existing chondrocytes; a single chondrocyte divides to form identical cell clusters within ECM matrix. Interstitial growth diminishes following maturation during early adulthood.
19
Q
Appositional growth
A
Surface growth—new cartilage stem cells divide and differentiate into chondroblasts along surface. Any type of cartilage that lacks a perichondrium will be unable to undergo appositional growth.
20
Q
Cartilage repair
A
Limited by vascular supply, limited by age. Higher repair capacity for cartilage containing a perichondrium due to stem cell source. Articular cartilage and fibrocartilage typically requires surgical intervention.
21
Q
Osteoarthritis
A
Most common chronic non-inflammatory disease caused by progressive loss of cartilage on the articular surface of bones.
22
Q
Rheumatoid arthritis
A
RA is an autoimmune disease caused by antibodies destroying synovial membranes and leading to chronic inflammation.
23
Q
What is the histological key difference that distinguishes TMJ from articular knee joint?
A
1) the type of cartilage
2)perichondrium
24
Q
Which ECM components in TMJ allows the cartilage to function as a shock absorber and resist compression?
A
Type I/II and proteoglycans
25
What type of cartilages is in the TMJ
Fibrocartilage
26
Osteoprogenitor cell
Small flat shaped stem cells capable of mitosis that differentiate into osteoblasts. Located in the CT covering bone surfaces (periosteum). Unipotent
27
Osteoblasts
Located on periphery/free edge of bone. Differentiate from osteoprogenitor cells. Do not undergo mitosis and are nullipotent. Responsible for synthesis of unmineralized bone ECM. Regulate deposition of inorganic minerals that form hydroxyapatite.
28
Osteocytes
Cells entrapped within mineralized bone matrix; reside in lacunae; contain cytoplasmic processes that connect to adjacent osteocytes via gap junctions. Do not undergo mitosis and are nullipotent.
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Osteoclasts
Large multinucleated cells found on edge of mineralized bone matrix. Don’t undergo mitosis and are nullipotent. Howships lacunae represents sight of active resorption.
30
Organic osteoid
Contributes 30% of total ECM. Of that 30%, 90% is type I collagen fibers. Non-fibrous proteins is about 10%. Contains a higher amount of fibers than GS when compared to ECM cartilage. The collagen fibers provide a scaffold and controls the extent of mineralization.
31
Inorganic matrix (of bone)
Hydroxyapatite (Ca10(PO4)6(OH2)) develops from inorganic calcium and phosphate ions. Bone is 70% inorganic. It is mineralized!
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Mineralization
1-deposit bone organic matrix (osteoid)
2-mineralize matrix by deposition of inorganic matrix
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What does mineralization depend on
Presence of Ca2+ ions and phosphate ions. Calcium and phosphate in the blood are hormonal regulated and depend on vitamin D.
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Failure to mineralize results in what
A decrease in percentage of inorganic matrix=soft bones.
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Long bones
Cylinder like shape that is longer than the bone is wide. Function to leverage. Femur, tibia, fibula, metatarsals, humerus, ulna, radius, phalanges.
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Short bones
Cube like shape, approximately equal in length, width, and thickness. Provide stability, support, while allowing for smooth motion. Carpals (wrist), tarsals (ankle/foot).
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Flat bones
Thin and curved. Points of attachment for muscles, protectors of internal organs. Sternum, ribs, scapulae, cranial bones, facial bones.
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Irregular bones
Complex shape, protect internal organs, vertebrae, pelvis, sacrum, base of skull.
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Sesamoid bones
Small and round, embedded in tendons. Protect tendons from compressive force. Patellae, pisiform.
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Periosteum
DRCT covers outer compact bone
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Endosteum
LCT lined medullary cavity and trabecular bone surfaces
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Marrow cavity
Filled with yellow marrow—mainly adipose in adult long bones
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Diaphysis
Shaft of lone bone. Comprised mainly of compact bone in walls, sparse trabecular bone, large medullary cavity. Provides structural support without increased weight. This is the first region ossified—prior to birth.
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Epiphysis
Proximal and distal articulating ends of long bone—orientation of trabeculae direct force to shaft. Appears as expanded rounded end (head) and contains a high amount of trabecular bone in adults. Covered on end with articular cartilage, no perichondrium. Second region to ossify during childhood.
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Metaphysis
Region between shaft and head (neck). In adult, contains high amount of trabecular bone and epiphyseal line—remnant of EGP and compact bone surface.
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Physis
Epiphyseal growth plate—area of hyaline cartilage present during childhood and adolescence. Hyaline cartilage allows for bone elongation through interstitial growth of cartilage. Last region to ossify
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Epiphyseal line
Mineralized growth plate
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Two layers of compact bone
External table- outer thicker layer of compact bone
Internal table- inner more thin layer of compact bone
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Periosteum
DRCT, covers both surfaces of compact bone
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Endosteum
LCT, lines medullary cavity and trabecular surfaces
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Marrow cavity
Found between spaces of the trabecular bone—filled with red marrow
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What structures are not present in flat bones
Epiphysis, diaphysis, metaphysis
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Structures within the periosteum and function of it
Site of tendon and ligament attachment and contains blood vessels, osteoprogenitor cells, and fibroblasts.
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What type of tissue is the periosteum
Dense regular connective tissue
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What type of tissue is the endosteum
Loose connective tissue
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Features of compact bone
Located in outer cortex, appears as dense area of bone, comprises 80% of total bone mass. Comprised of numerous osteons surrounded by concentric lamellar appearance
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Features of trabecular bone
Comprises 20% of total bone mass, located in center region of all bones, marrow cavity is located within the spaces of bone, has rod like lamellar arrangement.
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Osteons
Represent osteocytes/mineralized tissue arranged in circular pattern around neurovascular channel (HC). They are the the structural units associated with compact bone
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Haversian canal
Neurovascular channel oriented in the long axis of bone lined with osteoprogenitor cells/osteoblasts. BV in this canal that provides nutrients.
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Lacunae
Space in bone matrix; contain osteocyte cell body.
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Cannaliculi
Interconnecting canals in bone which contain the osteocyte dendritic processes. They function to connect osteocytes in adjacent lacunae to each other and connects the osteocytes to the Haversian canals. Cell processes of osteocytes communicate via gap junctions.
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Volkmann’s canal
Neurovascular canals that interconnect Haversian canals. Oriented perpendicular to Haversian canal.
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Extraosteonal lamellae
Parallel layers of outer cortical bone located just deep to the periosteum.
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Inner circumferential lamellae
Dense inner cortical bone located around the circumference of the marrow cavity.
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Interstitial lamella
Region between osteons—remnants of remodeling
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What can you see in decalcified vs dry ground prep
In decalcified prep you see living tissue in a dry ground only see inorganic material.
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What is the arrangement of trabecular bone
Parallel lamellar arrangement
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What type of bone is typically affected first by Ca++ homeostasis
Trabecular/spongy bone because it has less mass and more surface area
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Trabeculae
Bony plates aligned along lines of mechanical stress
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What structure is not seen in spongy bone
Osteons
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Intramembranous path
Direct ossification associated with skull bones, flat bones of face, scapula and clavicle. Osteoprogenitor—>osteoblast—>deposit ECM matrix which surrounds osteocytes.
Bone appears woven and then remodels into compact and spongy bone.
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Endochondral path
Indirect ossification that most long bones, short bones and irregular bones undergo.
Chondroprogenitor—>chondroblast—>chondrocyte—>hyaline—>replaced by woven bone—>adult compact and spongy
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What cells secrete the osteoid and what happens to those cells after
Osteoblasts secrete the osteoid and after it is mineralized the trapped osteoblasts become osteocytes.
74
In endochondral ossification what product do you start with
Start with hyaline cartilage before birth. Eventually becomes epiphyseal growth plate until age 20 or so and then becomes epiphyseal line in adult long bones.
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What structure allows long bones to continue to grow during childhood and adolescence
Epiphyseal growth plate
76
What does premature closure/ossification of the EGP yield
Short stature
77
Primary ossification site
Diaphysis
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Secondary ossification site
Epiphysis
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Does all hyaline cartilage calcify at some point during endochondral ossification
No, a layer of hyaline cartilage remains on articular joint surfaces and is called articular cartilage
80
Epiphyseal growth plate
A region of hyaline cartilage that allows for developing long bones to grow in length along the long axis of the bone
81
How is growth along the longitudinal axis is the EGP achieved
Mitosis of cartilage cells within cartilage matrix
82
What controls the closure of the growth plate
Sex hormones
83
Achondroplasia
Genetic disease causing short limbed dwarfism due to failure of cartilage to grow. This only affects bones that undergo endochondral ossification.
84
Resting zone
Random arrangement of inactive chondroblast
85
Zone of proliferation
Mitotic activity of chondrocytes—rows of isogenic groups
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Zone of maturation/hypertrophy
Enlarged lacunae chondrocytes mature; no longer mitotic; secrete alkaline phosphatase that facilitate calcification of cartilage matrix.
87
Zone of calcified cartilage (calcification)
Large empty lacunae b/c calcification of cartilage matrix lead to apoptosis of chondrocytes
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Zone of ossification/mineralization
Osteoblasts continue to deposit bone matrix on calcified cartilage and mineralize bone matrix—> immature (woven)bone
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What will always be the product of ossification
Woven bone
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Primary (woven) bone
First bone to appear during development and repair, rapidly deposited, irregular appearance of type I collagen, high number of osteocytes, low mineral content/unmineralized, appears as an open loose spongy arrangement of bone.
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Secondary (adult lamellar) bone
Found in adult bone following repair/remodeling, layered arrangement of collagen around vascular channel, cells in lacunae deposited in regular intervals, youngest cells closest to vascular channels, high mineral content, collagen and mineralized matrix organized parallel to each other within lamella and collagen fibers organized along lines of stress.
92
Two structural arrangements of adult lamellar bone
Compact and trabecular
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What does all bone tissue begin and end as?
Begins as primary woven bone and will be replaced by secondary adult lamellar bone.
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Appositional growth
Bone increases in diameter/thickness due to surface growth along periosteum and endosteal surfaces
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Interstitial growth
Only occurs in regions of cartilage of the growth plate. Chondrocytes divide and it allows developing bones to increase in length along the long axis
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Histological appearance of woven bone
Irregular and random arrangement of cells, random collagen fibers, lightly calcified, high in cell number and the bone appears loosely arranged in spicules
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Adult lamellar bone histological appearance
Parallel bundles of collage in thin layers called lamellae, regularly spaced cells that are heavily calcified.
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Mature compact (cortical) bone histological appearance
Parallel lamellae arranged, circumferential lamella densely packed with concentric lamellae, interstitial lamellae
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Mature (spongy) bone histological appearance
Parallel lamellae are interconnected as thin spicules or plates known as trabeculae which are each covered by endosteum.
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Locations of woven bone
Developing and growing bones, first type of bone deposited in fracture repair, forms the hard callus of bone fractures.
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Adult lamellar bone locations
All normal regions of adult bone; deposited during bone remodeling of bone fracture.
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Locations of compact bone
Thick outer region of bones beneath the periosteum. Wall of diaphysis, external/internal tables
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Locations of trabecular bone
Inner region of bones interspersed between marrow cavities; long bone it is in the epiphysis and metaphysis and in flat bones in the dipole.
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Bone modeling/remodeling occurs when
During periods of growth and at points of mechanical stress or following repair. It functions to maintain bone mass or change existing shape
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Wolffs law
every change in bone function is followed by changes in the internal and external structural architecture
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Environmental stimuli that trigger remodeling/modeling
Hormones/growth factors, maintenance of ion homeostasis, mechanical load/force/stress, injury or trauma
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Possible outcomes of stimuli that trigger bone modeling and remodeling
Bone resorption or bone deposition
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Bone resorption
Osteoblasts recruit osteoclasts to resorb bone
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Bone deposition
Osteoblasts deposit bone
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What runs at various angles and runs along lines of stress
Trabeculae and they transmit the stress to cortical bone
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Where does remodeling occur
On the same same surface because remodeling is a balance between deposition and resorption
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Where does modeling occur
Modeling occurs on a different surface to increase bone mass and to change shape of bone
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Phases of modeling/remodeling
Activation-recruitment of osteoblasts
Resorption-degradation of mineralized matrix by osteoclasts via acid phosphatase enzymes
Reversal-cessation of resorption/osteoclasts disappear.
Deposition-OB deposit new bone matrix at site of resorption;leads to reversal line
Resting-bone formation ceases and OB inactive
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What happens to bones when they do not undergo strain
They can undergo disuse atrophy
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Repair
Bone is a stable cell population containing stem cells that may be induced to renew and differentiate
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What bones undergo repair
Flat and long
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Direct repair
Occurs if ends stabilized and/or close together or small gap—uses intramembranous ossification
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Indirect repair
Mechanism by most fracture repair—uses cartilaginous callus follows. Follows steps of endochondral ossification due to large gap between fractured ends
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Four major stages of indirect fracture repair
Hematoma formation/inflammation
Fibrocartilaginous callus formation
Bony callus formation
Remodeling of bony callus, deposition of lamellar bone
*no scar in bone since bone is replaced w new bone
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Anatomical divisions of the nervous system
CNS and PNS
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Functional divisions of the nervous system
Somatic nervous system and autonomic nervous system
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Divisions of the autonomic NS
Sympathetic and parasympathetic
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How do neurons communicate
Synapses
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Neurons
Structural and functional cell that is exciteable and receives, processes and transmits info rapidly via electrochemical signals called action potentials
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Neuroglial cells (glial cells)
Supportive cells that provides structural integrity and functional support to allow normal nerve function
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Key features of glial cells
No synapses between cells, function to maintain ionic environment, myelinate nerve fibers, phagocytize debris and they are located in CNS and PNS
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What germ layer gives rise to the CNS
Neural tube
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Development of CNS
Neuroepithelium rapidly proliferate and give rise to neurons and glial cells of the CNS.
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Neurons and glial cells of the CNS
Motor neurons, inter neurons, Astrocytes, oligodendrocytes, and ependymal cells
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Development of PNS
NC cells arise from the lateral edge of the neural plate and give rise to neurons and glial cells of PNS
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Neurons of the PNS
Pseudounipolar, postganglionic sympathetic (motor), postganglionic parasympathetic (motor)
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Where are pseudounipolar neurons located and what function do they serve
They are in the DRG and cranial nerve ganglia. Function to receive info from skin, joints, muscle and other regions about touch, pressure, temp, pain, stretch, proprioception
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Where are postganglionic sympathetic neurons located
Paravertebral and prevertebral ganglia
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Postganglionic parasympathetic neuron locations
Enteric ganglia
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Glial cells of the PNS
Schwann cells and satellite cells
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Flow of information of a neuron
Dendrites, cell body, axon, and terminus then to next neuron or effector tissue (ex:muscle)
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Dendrites
Receptor processes, 1 or more branch extensively in a tree like appearance and are unmyelinated. They receive signals from neurons via a synapse and convey it to the cell body
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What determines morphological identification of a neuron
Number and shape of dendrites
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Dendritic spines
Bud like extensions at the site of synapse and they increase area for synaptic contact
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Contents of a dendrite
Organelles, nissl, and cytoskeletal elements
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Contents of a cell body
Nucleus, cytoplasm, axon hillock
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What organelle is responsible for neurotransmitter synthesis
rER
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What organelle of the cell body lack Nissl substance
Axon hillock and that’s what distinguishes it form dendrites
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Axon
Conveys information away from one cell body to another to another or an effector cell. Has no organelles but the plasma membrane is specialized for impulse conduction
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Initial segment
Between axon hillock and myelin sheath and its the site of action potential generation
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What cells myelinate axons
Schwann cells and oligodendrocytes
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Synapses
Functional points of contact that facilitates communication between neurons or neurons and effector cells. Point of information transfer
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Morphological classifications of synapses
Axodendritic, axosomatic, axoaxonic
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What is the endpoint of an axon
Terminal arbor
150
Terminal bouton
Functional point of contact containing mitochondria and neurotransmitter containing vesicles
151
Electrical action potentials
Occurs through gap junctions, its faster based on direct flow of ions between adjacent cells and it is bidirectional. These are limited in number in adult humans.
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Cells that utilize electrical AP
Astrocytes, smooth muscle, cardiac and neuroendocrine cells
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Chemical AP
Occurs through neurotransmitter chemicals, most common, unidirectional, can be inhibitory or excitatory
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What determines if an AP is excitatory or inhibitory
Type of NT, amount of NT, type of receptor on effector cells and the amount of receptors expressed
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Steps involved of chemical synapse
Release of NT from presynaptic membrane and diffusion across synaptic cleft
NT binding to specific receptors on postsynaptic membrane that stimulates or inhibits AP generation
An AP on postsynaptic membrane elicits response isn’t he postsynaptic cell
Enzymatic degradation or clearing of NT terminates the signal
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Functional adaptation of axonal transport
Neuron secretory zone is far from cell body. Neurons are critically dependent on highly regulated bi-directional movement of molecules.
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Anterograde transport
Movement of molecules/organelles away from the cell body to the axon terminals via kinesin. Transport in synthesized NT within vesicles to synaptic terminal
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Retrograde transfer
Movement of materials from axon terminals to the cell body by Dynein. Recycle synaptic vesicles
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Clinical significance of retro and anterograde pathways
They are important pathways for some neurotropic viruses (herpes simplex virus, polio,rabies) to invade the PNS or CNS
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How to classify a neuron
Based on number of processes extending from cell body
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Classification of neurons
Based on morphology, function, location, pathway and NT specificity
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Multipolar neurons
One axon, and two or more dendrites. They have cell bodies present in the brain, spinal cord and autonomic ganglia. All motor neurons and interneurons.
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Functions of multipolar neurons
Transmitting somatic and visceral motor impulses from brain to effector organs. Multipolar neurons perform the majority of cognitive processes
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Bipolar neurons
Very rare. Round or oval cell body, one axon and one dendrite, associated with receptors for special senses. Found in sense organs like retina, olfactory epithelium
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Pseudounipolar neurons
Spherical cell body, one axon that divides close to cell body into two long axonal branches. One to periphery and other to CNS. Develops from bipolar neurons and majority are sensory neurons close to CNS
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What germ layer gives rise to Pseudounipolar neurons
neural crest cells
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Where are the cell bodies of pseudounipolar neurons located
Dorsal root ganglia and cranial nerve ganglia
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Function of Pseudounipolar neurons
Sensory neurons both visceral and somatic of the PNS. Receives information from skin, joints, muscles and other body regions
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Somatic sensory
Mostly conscious perception and examples influe touch, pain, pressure, vibration, temperature, and proprioception from skin body wall and limbs.
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Visceral sensory
Mostly unconscious perception. Very few examples in the body such as aortic and carotid bodies. Sense CO2 levels, blood pressure, gut distension from internal organs
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Special sensory
Smell, sight, balance, hearing
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Motor neurons
Convey impulses from CNS or ganglia to effector cells. Also called efferent.
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Somatic motor
Send voluntary impulses to skeletal muscles. Consciously controlled and cell bodies are located in the ventral horn spinal cord (CNS)
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Visceral motor
Transmits involuntary impulses to smooth muscle and cardiac conducting cells and glands. Preganglionic in the lateral horn of SC and postganglionic (autonomic ganglion) located in the PNS
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Interneurons
Integrative neurons and make up 99% of all neurons. Form a communicating and integrating network between sensory and motor neurons. Cell body and all processes located entirely within the CNS. They play a very important role in reflex arcs.
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Hermetic gingivostomatitis
Cold sores or fever blisters that are reoccurring lesions within or around the lips of the oral cavity. The trigeminal sensory neurons become the target of the virus and the virus remains dormant until triggered via stress or illness. Uses retrograde transport.
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Neuroglia
Do not propagate AP’s, only nuclei of glial cells are seen in routine histological sections, functionally interdependent with neurons.
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Neuroglia function
Physically support/protection for neurons
Insulation for nerve cell bodies and processes that facilitates rapid transmission of nerve impulses
Repair of neuronal injury
Regulation of internal fluid environment of CNS
Clearance of NT form synaptic cleft
Metabolic exchange between vascular system and neurons
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CNS glia
Atrocytes, oligodendrocytes, ependymal cells, microglia
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PNS glia
Satellite cells, Schwann cells, macrophages/phagocytosis cells
181
Two types of astrocytes
Protoplasmic and fibrous
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Protoplasmic astrocytes
Prevalent in gray matter, numerous short branching processes
183
Fibrous astrocytes
Prevalent in white matter and have fewer processes that are relatively straight
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End feet
Astrocytes processes end expansions. Cover myelinated axons at nodes of ranvier and at synapse. Line subpial surface of CNS forming glia limitans. Lines BV’s forming blood brain barrier.
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Blood brain barrier
Highly selective, formed by tight junction of endothelium surrounded by a basement membrane and astrocytes end feet.
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Function of astrocytes
Modulate ionic composition by clearing K+ following action potential. Remove NT from synaptic, move metabolites and waste to and from neurons.
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Ependymal cells
Epithelial like lining of ventricles of brain and spinal(central) canal. Single layer of cuboidal columnar wit no basement membrane. Modified ependymal cells are associated with capillaries that produce CSF.
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Apical surface modifications of ependymal cells
Cilia and microvilli. Cilia circulates CSF and microvilli absorb it.
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What structure produces CSF
Choroid plexus
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Microglia
Phagocytosis cells derived from granulocyte/monocyte progenitors. Small elongated nuclei with short twisted processes.
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Satellite cells
Cells surrounding neuronal cell bodies in ganglia. They maintain micro environment around neuronal cell bodies in ganglia, providing insulation and facilities metabolic exchange.
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Satellite cells of DRG
No synapses, pseudounipolar, arranged in clusters and myelinated. Satellite cells completely surround cell bodies
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Satellite cells around parasympathetic and sympathetic ganglia
Satellite cell incompletely surrounds cell bodies.
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Schwann cells
Produces and maintains myelin sheath in PNS, supports one myelinated and many unmyelinated axons. AIDS in cleaning up debris and axonal regeneration. Basement membrane is present.
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Myelin sheath
Insulates axons and concentrates ion channels at nodes of ranvier. Results in increased nerve conduction. Absent at the axon hillock, nodes of ranvier and axon terminals.
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Myelin formation
Schwann cell plasma membrane surrounds axon and wraps around axon in a spiraling motion forming multiple layers. Cytoplasm in squeezed out of inner layers and stabilized by myelin specific proteins.
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What permits transport in myelin formation
Schmidt-lantern clefts
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Nodes of ranvier
Represents junction between two adjacent Schwann cells. Site of concentrated ion channels that facilitate saltatory conduction.
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Oligodendrocyte
Produces and maintains myelin in CNS, gives off multiple tongue-like processes that can myelinate one or many nearby axons. They express myelin specific proteins to maintain myelin layers. Aligned in rows.
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Gillian-Barre syndrome
Acute demyelination disease of the PNS considered an autoimmune disease following viral or bacterial infection, immune system attacks the myelin specific proteins of Schwann cells.
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Multiple sclerosis
Chronic demyelinating disease of the CNS. Immune system attack the myelin specific proteins of oligodendrocytes.
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Functional overview of CNS
Integrate, process and coordinate sensory input. Execute motor responses. Regulation of homeostatic mechanism. Execute reflexes from the body and organs.
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Anatomical divisions of the CNS
Grey and white matter
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Gray matter
Contains neuronal cell bodies, axons, dendrites and CNS glia. Site of synaps. Outmost covering of the cerebral cortex and it contains nuclei.
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Nuclei
Islands or clusters of grey matter within the cerebrum, cerebellum and brain stem that are functionally and spatially related neuronal cell bodies.
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White matter
Forms inner core of CNS. Contains axons, CNS glia, and BV’s. Contains tracts or fasiculi.
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Tracts
Bundle of parallel axons that form motor and sensory tracts and connect neighboring and distant nuclei. They are functionally related.
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Spinal cord
Made of grey and white matter.
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Somatic motor neurons
Terminate in skeletal muscle in the body and have cell bodies in the ventral/anterior horn of the spinal cord.
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Visceral motor
Relay info to ganglion neurons in the PNS which then terminate on glands, smooth and cardiac muscle, and BV’s. Cell body is located in the lateral horn of the SC
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Integrative/relay or interneurons
Form a chain of interconnecting neurons from spinal cord to cerebral cortex. Cell body in dorsal horn of spinal cord.
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Organization of PNS
Consists of peripheral nerves with specialized nerve endings and ganglia (motor and sensory) containing neuronal cell bodies outside the CNS.
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Functional divisions of the PNS
Somatic nervous system and autonomic nervous system.
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Somatic nervous system
Provides sensory and motor innervation to all parts of the body except cardiac muscle, smooth muscle and glands. Sensory division transmits touch, pain, temp. Motor division only innervates skeletal muscle.
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Autonomic nervous system
Associated with involuntary visceral motor and accompanying sensory function to glands and organs. Sympathetic division is accompanied by visceral pain fibers and parasympathetic is accompanied by visceral afferent reflex fibers.
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Peripheral nerve
Consists of nerve fibers that carry sensory and motor information between the organs and tissues of the body and brain/spinal cord.
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Peripheral nerve, nerve fiber
Consists of axon, myelin adn Schwann cell held together by CT. peripheral nerve fibers can be myelinated or unmyelinated. Consists of spinal, cranial and named peripheral nerves.
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Endoneurium
Loose CT that surrounds nerve fibers. Collagen type III fibrils interlink adjacent nerve fibers into fascicles.
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Perineurium
Squamous perineurial cells ensheath fascicles forming 2-6 layers of specialized CT.
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What creates the blood-nerve barrier
Perineurial cell barrier
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Blood nerve barrier
An active diffusion barrier between capillaries and nerve fibers.
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Epineurium
Dense irregular CT that surrounds and binds nerve fascicles into a common nerve. Primarily type I collagen.
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Sympathetic division of autonomic NS function
Energy expending/fight or flight
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Parasympathetic division of autonomic NS function
Energy conserving/rest and digest
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What neurotransmitters are used in sympathetic vs parasympathetic neurons.
Sympathetic- acetylcholine, norepinephrine, epinephrine
Parasympathetic-acetylcholine
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Another name for sympathetic division
Thoracolumbar
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Another name for parasympathetic division
Craniosacral
228
Pre and post ganglionic lengths of sympathetic neurons
Pre is short because ganglia are close to SC and the post is long.
229
Choroid plexus
Produces cerebrospinal fluid
230
What kind of capillaries are in the choroid plexus
Fenestrated capillaries
231
What maintains the blood CSF barrier and how
Ependymal cells via tight junctions
232
What cells secrete CSF
Ependymal cells through selective active transport mechanism
233
Meninges
Membranous CT coverings of the CNS. They protect the brain and spinal cord, provide supportive framework for vessels and enclose fluid filled cavities (subarachnoid space)
234
Dura mater
DRCT composed of elongated fibroblasts and high concentration of collagen. Outer most layer
235
Arachnoid mater
Large fibroblasts closely Apposed and attached by tight junctions. Devoid of collagen, arachnoid trabeculae bridge arachnoid space. Middle layer.
236
Pia mater
Composed of epithelium, collagen type I, elastic and reticular fibers. Directly covers the surface of the brain and spinal cord.
237
What structures do you pass through when doing a lumbar puncture
Skin, subcutaneous, supraspinous ligament, interspinous ligament, ligamentous flavum, epidural space, dura mater, arachnoid mater, subarachnoid space to CSF
238
Fibrocartilage always lacks a perichondrium except in one joint, what is it?
TMJ. It has a perichondrium and a Fibrocartilage covering as opposed to hyaline
