Quiz 3 Flashcards
1
Q
describe the vascularation of cartilage
A
avascular
2
Q
what three things does cartilage lack?
A
1.AVASCULAR
2.Lacks sensation
3.Lacks lymphatic vessels
3
Q
what is the primary tissue in the fetal skeleton and growing bones
A
cartilage
4
Q
camarativly what is the water content of cartilage
A
↑ Intracellular water
content to bear
mechanical stress
5
Q
Chondroblasts
A
Cells that produce cartilage matrix
6
Q
Chondrocytes
A
Mature cartilage cells that reside in lacunae
7
Q
Perichondrium
A
Dense sheet-like connective tissue surrounding cartilage
8
Q
lacunae
A
provide a home for a cell in bone and cartilage,the cell are osteocytes in bone and chondrocytes in cartilage
9
Q
what are the two ways carilage grow?
A
appositional and interstital
10
Q
Appositional cartilage growth
A
new cartilage forms at the surface of existing cartilage
11
Q
define Interstitial growth cartilage growth
A
- new cell forms within an existing cartilage mass by
mitotic
-make isogenous groups
12
Q
Territorial matrix
A
surrounds isogenous groups
13
Q
Interterritorial matrix
A
found in the space between groups of chondrocytes (identify in lab)
14
Q
what is in the extracellular matrix of cartilage?
A
collagen(type II)
proteoglycans
multiadhesive glycoproteins
15
Q
What causes the staining to vary between the territorial and interterritorial matrices?
A
The matrix directlyaround them
has alot of glycosaminoglycans. Stains darker b/c flycosaminoglycans have high negative charges which attracts Na and water
16
Q
what happens to water and flexability when you decrease GAGs in cartilage?
A
↓ GAGS
↓ water
↓ flexibility
17
Q
what percent of intercellular water is bound tightly to aggrecan in cartilage?
A
60% to 80% of the net weight of cartilage
18
Q
how is cartilages consisitancy good for its fuction?
A
-The firm consistency of the cartilage ECM allows the tissue to accommodate mechanical stress
- The high water content makes cartilage a very effective shock absorber
-It also facilitates smooth gliding motions in joint cavities
19
Q
how does the cartilage get nurtients if its avasculature
A
-The perichondrium is highly vascularized
-Cartilage is surrounding by connective tissue which is highly vascularized the nutrients from perichondrium diffuse and nurish cartilage
20
Q
how does vascularization affect healing in cartilagee?
A
Very poor ability to heal
21
Q
Osteoarthritis
A
*degenerative joint disease
* Pathogenesis usually unknown
* Related to aging and trauma
* Decrease proteoglycan content
* Type II collagen production inhibited
* Superficial layer affected first and may eventually extend to the bone
22
Q
which catilage does not have a perichondrium?
A
articular cartilage and fibrocartilag
23
Q
label
A
24
Q
properties of hyaline cartilage
A
- Flexible but resilient
- Respiratory system (larynx, trachea, bronchi), costal cartilage, nose, articular cartilage, epiphyseal plate, fetal skeleton
- template cartilage
25
properties of elastic cartilage
-Contains elastic fibers
-Provides flexibility
-Epiglottis and external ear
-add on to hyline
26
properties of fibrocartilage
*Contains thick collagen fibers
* Shock absorber
* Intervertebral discs, menisci of knee and jaw, pubic symphysis
*add on the hyline
27
what type of collage in is hyaline?
Type II collagen
28
what type of cartilage is this?
Hyaline
29
what type of cartilage is this and what is the stain?
elastic
ver hoff stain
30
what type of cartilage is this?
fibrocartilage
31
what type of collagen is in fibrocartilage?
both type I and type II
32
what is the Chondrocyte arrangement in Fibro-cartilage
Parallel rows
33
Organic component of extracellular matrix in bone
is called osteoid and
contains Type I collagen and other proteins
34
inorganic component of extracellular matrix in bone
is called hydroxyapatite gets added to organic commponent and stregthens it
35
how is the blood supply and innervation in bone?
Bone is richly vascularized and innervated
* Blood vessels and nerves enter through nutrient foramina
36
periosteum
| bone
-outer sheet of connective tissue
-outer fibrous layer of dense connective tissue
o Inner cellular layer with cells (osteoblasts, bone lining cells, osteoprogenitor cells)
37
endosteum
Bone cavities are covered by endosteum
One layer of cells lines the cavity
38
macroscopic classifications of bone
Compact/cortical bone: Thicker
Spongy/trabecular/cancellousbone
39
microscopic classifications of bone
woven bone: no nice rings
lamellar bone: looks like a tree truck
40
interstitial lamellae
Between the osteons are remnants of previous concentric lamellae
41
Outer circumferential lamellae
outer surface of the shaft of a long bone
42
Inner circumferential lamellae
inner circumference of the shaft of a long bone
43
Haversian (central) canals
small canals containing blood vessels and nerves travel which lamellae are organized concentrically around
44
Volkmann’s (perforating) canals
small canals containing blood vessels and and nerves that travel between osteons, run at right angles to the long axis of the osteon
45
Trabeculae
crisscrossing beams and plates of spongy bone
46
Compact/cortical bone structure
Lined by periosteum and endosteum
Composed of lamellae organized in
osteons
47
Spongy/cancellous/trabecular
bone structure
Lined by endosteum
Composed of lamellae organized in
trabeculae
48
Woven Bone structure
* More cells, randomly arranged
* Interlacing arrangement of collagen fibers
* More ground substance
(stains more basophilic)o
* immature
* no lamellae
49
lamellar bone structure
*Less ground substance (stains intensely eosinophilic)
* Less cells, organized in circular fashion in lamellae
* Incompactbone:composed of cylindrical units called osteons
* Long axis of osteon parallel to long axis of bone
* In trabecular bone: composed of trabeculae
50
how long does it take to put down woven bone?
Woven bone is deposited rapidly.
51
what type of bone is this
Woven Bone
52
What type of bone is this?
lamellar bone
53
Tendon
Fibrous connective tissue sheath that attaches muscle to bone and other structures, functions to move bone or structure
54
Ligament
Attaches bone to bone and functions
to stabilize
55
Joint
Site where two skeletal components come together. Two general categories:
o Synovial- skeletal elements separated by cavity
o Solid- no cavity, skeletal components held together by connective tissue
56
what type of joint is this?
synovial joint
57
what are the three components of a synovial joint?
Articular cartilaage, articular capsule, joint cavity
58
where is Articular cartilage located?
at the ends of epiphyses
59
where is synovial fluid located in a synovial joint?
in the joint cavity
60
what are the two layers of the articular capsule?
-Fibrous layer continuous with a ligament Type/ inserting into the periosteum of both bones
-Synovial membrane lining the capsule and producing synovial fluid
61
how do synovial joints get nutrients?
* Articular surfaces of synovial joints lack a perichondrium
* Synovial fluid lubricates the joint and supplies nutrients and oxygen to the articular cartilage
62
what are they key charcteristics of the fibrous layer of the articular capsule?
o Dense connective tissue
o Surrounds and stabilizes joint
o Parts may become thickened to form ligaments that further stabilize the joint
63
what are they key charcteristics of the synovial membrane layer of the articular capsule?
o Attaches to the margins of joint surfaces at the interface of cartilage and bone to enclose cavity
o Highly vascular
o Produces synovial fluid that lubricates the articulating surfaces and nourish the cells of the joint cavity
64
what two cell types (synoviocytes) are found in the synovial membrane?
Type A cells and Type B cells
65
what are type A cells in the Synovial Membrane?
o Macrophage-like cells
o Derived from blood monocytes to monitor the synovial fluid
o ~25% of the cells lining the synovium
66
what are type B cells in the synovial membrane?
o Fibroblastic synovial cells
o Produce hyaluronan and proteoglycans o Transported along with water into the
joint cavity to form the synovial fluid o Majority cell lining the synovium
67
what is the organic component of bone?
osteoid and contains Type I collagen and other proteins
68
what is the inorganic component of bone?
hydroxyapatite and contains calcium phosphate and calcium carbonate
69
which bone cells are derived from mesenchymal stem cells?
The osteoprogenitor cell, osteoblast, osteocyte, and bone lining cell
70
which bone cell originate from the hematopoietic stem cell?
The osteoclast
71
what is the structure, funtion, and location of the Osteoprogenitor Cells?
Structure:
* Squamous shaped cells (not responsible for identifying in lab)
waiting
Function:
* Derived from mesenchymal stem cells
osteoblasts
* Osteoprogenitor cells are responsive to stimuli - they then differentiate into bone-forming cells called osteoblasts
* Retain their ability to undergo mitotic division
Location:
* Found in the cellular periosteum and endosteum
72
what cells are these?
osteoblasts
73
what is the structure of osteoblasts?
o Cuboidal shaped cell in single sheet along surface of bone o (Bound to the bone surface via integrins)
o (Joined to neighboring cells via adhering and gap junctions)
74
what is the fuction of osteoblasts?
o Differentiated cell that secretes the organic bone matrix
o Capable of cell division
o Secrete type I collagen and bone matrix proteins which form unmineralized bone/osteoid
75
where are osteoblasts located?
Exclusively at the surface of where bone is actively being laid down
76
chemically how is the bone laid down?
-Osteoblasts release matrix vesicles containing alkaline phosphatase and other enzymes that help concentrate local PO43− ions
-High Ca2+ and PO4− ion concentrations cause calcified nanocrystals to form in and around the matrix vesicles
-These crystals grow and mineralize further with formation of small growing masses of calcium hydroxyapatite [Ca10(PO4)6(OH)2] that surround the collagen fibers and all other macromolecules
-Eventually, the masses of hydroxyapatite merge as a confluent solid bony matrix
77
what cells are the dots in the bone?
ostocytes
78
how do osteocytes form and what do they form from?
-As osteoblasts secrete the products required for bone formation, they become surround by the bone matrix
- Once surrounded by the matrix, the osteoblast becomes an osteocyte
79
what is the struture of an osteocyte?
o Round-ish/flattened cell residing in a lacuna and
surrounded by bone matrix
o Canaliculi often visible in ground bone sections
80
what is the fuction of an osteocyte?
-Responsible for maintaining the matrix of bone
-Respond to mechanical stimuli
81
what are canaliculi and what is their role?
-Each osteocyte occupies a lacuna and extends a cytoplasmic processes through canaliculi (small canal ) to contact the processes of other osteocytes and bone cells
-The dendritic processes of the osteocytes in the
Canaliculi with osteocyte process
canaliculi allows for nutrients from blood
vessels to diffuse and pass from cell to cell
82
what kind of cell is this
osteocyte
83
what type of cell is this?
Bone Lining Cells
84
what is the structure and location of a bone lining cell?
Structure:
o Flat, squamous-looking cells
Location:
o Surface of bone
85
what is the fuction of a bone lining cell?
o Derived from osteoblasts that are not actively producing bone
o Incapable of mitotic division, but may be able to differentiate into osteoid secreting cells as needed
o Communicates via gap junctions with osteoblasts and osteocytes
86
what kind of cell is A and what kind of cell is B?
A. osteoclast
B. osteoblast
87
what is the structure and location of osteoclasts?
Structure:
-Large, multinucleated cell that has a “polarity”
Location:
-Found at the surface of bone where bone is actively beingremoved/reabsorbed
88
what is the function of osteoclasts?
Break down bone
and control circulating Ca levels
89
what region of the cell is the arrow pointing to?
Shallow bays known as resorption bays/lacunae or Howship’s lacunae represent cellular activity
90
what is a ruffled border is osteoclasts?
Numerous plasma membrane infoldings to increase surface area for exocytosis of hydrolytic enzymes and secretion of protons
91
what is the sealing/clear zone in osteoclasts?
Actin filaments and extracellular adhesion molecules tightly bind the cell to the bone surface and provide a tight seal between the plasma membrane and prevent leakage
92
what is the Basolateral zone in osteoclasts?
-Functions in exocytosis of digested material
-Transport vesicles with degraded bone material that was endocytosed at ruffled border fuse and release contents
93
phsiologically what happens during bone resorption?
* ↑ osteoclast activity
* PTH produced when circulating Ca2+ is low
* PTH stimulates osteoblasts and osteocytes to secrete RANKL
* RANKL binds to RANK on osteoclast precursors
* Osteoclast activity activated and increase in
circulating Ca2+
94
phsiologically what happens during bone formation?
* ↓ osteoclast activity
* Osteoblasts secrete osteoprotegrin (OPG)
* OPG binds RANKL (prevents RANK/RANKL binding)
* Osteoclast activity inhibited and decrease in circulating Ca2+
95
what is osteomalacia?
* Lack of mineralization of bone results in low bone density
* Caused by vitamin D or calcium deficiency
* Called Rickets in children
* Soft bones, bowed legs
*decreased osteoblast activity
96
what is osteopetrosis?
* Osteoclasts cannot digest/resorb bone minerals
* ↓ Osteoclast activityy
* Osteoblasts continue to build bone
* Results in hyper-mineralization of bone and abnormally high bone density
* Bones are brittle
* Skull foramina close off, pinching nerves
97
what is Osteoporosis?
* Excessive bone resorption
* Aged and post-menopause
*increased osteoclast activity
98
what are the steps in bone remodelling?
Steps:
1. Osteoclasts tunnel into existing bone matrix (the canal diameter determines the diameter of the osteon) (cutting cone)
2. Osteoprogenitor cells invade the newly formed tunnel and line the surface
3. Osteoblasts fill the canal by depositing the bone matrix (osteoid) in lamellae (closing cone)
4. Some cells get trapped in lacunae (osteocytes)
5. Lamellae are added from the periphery inward,
narrowing the diameter of the osteon
6. Osteoblasts differentiate to bone lining cells, osteoclasts undergo apoptosis
99
The bone-remodeling unit consists of:
o Cutting cone (resorption tunnel)
o Closing cone
100
what are the two processes for bone development?
Intramembranous ossification and Endochondral ossification
101
what is intramembranous ossification?
Osteoblasts differentiate directly from mesenchyme and begin secreting osteoid
102
what is endochondral ossification?
A preexisting matrix of hyaline cartilage is eroded and invaded by osteoblasts, which then begin osteoid production
103
what are the steps of intramembranous ossification?
Steps:
a) Ossification centers form within a condense sheet of mesenchyme, which will become the future periosteum. Here, osteoprogenitor cells arise and proliferate around a network of developing capillaries
b) Secreted osteoid traps osteoblasts, which become osteocytes. Osteoid becomes mineralized and forms woven bone
c) Neighboring ossification centers fuse. Trabecular matrix and periosteum form
d) Compact bone develops superficial to trabecular bone
e) Mesenchymal regions that do not undergo ossification give rise to the endosteum and the periosteum of the new bone.
104
what process is taking place?
Intramembranous Ossification
105
what kind of bone does endochondral ossification form?
Forms most bones in body, including long bones
106
what is the long bone anatomy?
* Diaphysis: long shaft
* Epiphysis: end of bone
* Metaphysis: what connects the 2
107
what is interstitial growth in bones?
-increase in length
-Growth at growth plates happens in development
108
what is appositional growth?
| of bone
getting thicker
109
what are the steps of enochondral ossification?
1. Fetal hyaline cartilage model develops
2. Cartilage calcifies and periosteal bone collar forms around diaphysis
3. Primary ossification center forms in the diaphysis
4. Secondary ossification centers form in epiphyses
5. Bone replaces cartilage, except the articular cartilage and epiphyseal plates
6. Epiphyseal plates ossify and form epiphyseal lines
110
what phase of bone development is this and what are the charateristics?
Zone of Resting/Reserve Cartilage: typical hyaline cartilage with chondrocytes
111
what phase of bone development is this and what are the charateristics?
Zone of proliferation: chondrocytes divide rapidly and form colums of cells parallel to the long axis of bone; cells produce collagen fiber and cartilage matrix
112
what phase of bone development is this and what are the charateristics?
zone of maturation and hypertrophy: elarged, swollen cells producing type I and X collagen
113
what phase of bone development is this and what are the charateristics?
Zone of degeneration: loss of chondrocyte, calcification of cartilage matrix, turning into a scaffold
114
what phase of bone development is this and what are the charateristics?
Zone of ossification: bone tissue appears, osteoblasts lay doen primary bone on the calcified cartilage matrix, the cartilage is resorbed leaving only the primary bone
115
what kind of bone formation is this?
Endochondral Ossification
116
what are the steps of Bone Fracture Repair
o Hemorrhage: neutrophils are the first cells to arrive, then macrophages
o Fibroblasts and capillaries proliferate into to site of the injury and form new loose connective tissue and cartilage (procallus formation)
o The procallus helps to stabilize the fractured bone
o The procallus is invaded by regenerating blood vessels and proliferating osteoblasts 1-Empalate for bone repair
o Woven bone is laid down and replaces fibrocartilaginous tissue, becoming hard, bony callus
o Woven bone is replaced with lamellar bone and osteoclasts remove any remnant of the callus restoring the shape of the bone
117
what is osteoprotegrin(OPG)
a protien that osteoblasts secrete which binds RANKL and has the effect of protecting bone from resorption because OPG-bound RANKL can no longer bind RANK receptor
118
epiphyseal line
the location of the closed growth plate
119
sesamoid bone
bones within tendons
120
fibrodysplasia ossificans progressiva
disease in which extra-skeletal bone forms from damaged soft tissue during its repair
121
the epidermis forms from what?
ectoderm
122
the dermis from from what?
mesenchyme
123
what is the major cell off the integument?
Keratinocyte
124
Periderm
| skin
has important developmental function in fetus but is slophed off before birth
125
when do the Dermis/hypodermis differentiate?
Differentiation after 1st trimester
126
what three layers in the epidermis are present during the first trimester?
periderm
intermediate layer
basal layer
127
Desquamation
shedding of skin cells
128
Cornification
final stage of keratinization and programmed cell death
129
what layer of the epidermis does cell divistion take place?
basal layer
130
what are the Major functions of keratinocytes?
* Structural
* Protection-Barrier
* Antibacterial
* Vitamin D production
131
what structures in keratinocytes that contribute to the physical strength of the integument?
desmosomes, hemidesosomes, and keratin filaments(which anchor into desmosomes)
132
Pemphigus
-Mutation In desmosomes
-Skin that has lost structural Integrity
133
what are the roles of the upper layer of the epidermis?
form a passive barrier against dehydration, mechanical, chemical and pathogen insults
134
what granules are in the S.granulosum
Lamellar granules and Keratohyalin granules
135
which granules can you see in the S. granulosum with an H&E stain
Keratohyalin granules
136
Brick-and-mortar model of the
stratum corneum
keritin on inside
lipids on outside as mortor
137
Tonofilaments
bundling of Keratin filaments
138
what are the structural protiens of the stratum corneum?
Involucrin, Loricrin, small proline-rich protiens
139
Filaggrin
Filaggrin is a filament-associated protein that binds to keratin fibers in epithelial cells
140
Filaggrin gene mutations are assoaciated with what skin condition
eczema
141
what kind of molecules can cross the epidermal barrier and why is this useful?
moderately lipophilic small molecules
we can deliver drugs through the skin using skin patches
142
what are the major fuctions of vitamin D?
-Calcium absorption by GI tract
-Calcium re-absorption by kidney
-Bone resorption by osteoclasts
-maintain serum calcium levels
143
Why do ppl with darker skin feel the effect of vitamin D deffiency more
becuase people with darker skin have a tendency to produce ↓ vitamin C
144
Dietary sources of Vitamin D
-Milk enriched in vitamin D
-Oranges
-Salmon
145
how does UV light make vitamin D?
1. UV light hydrolyzes 7D into previtamin D3
2. VD3 goes through the blood vessels to the liver
3. then in the kidneys it is activated into calcitriol which is active vitamin D
146
what is the role of Melanocytes?
provide protection against the damaging effects of UV radiation
147
How are melanin granules made?
tyrosine is converted to melanin by tyrosinase
148
what type of secretion do melanin granule do?
cytocrine secretion
a small peice of the cell is exchanged
149
why are the melanin granules not usually in melanocytes
the pigment is transported rapidly to keratiocytes and the granules cover the DNA to protect it from UV redation
150
what enzyme is missing in albinos?
tyrosinases
151
why do some people have darker skin colors?
In darker-skinned individuals, more mela-nin is produced,
melanosomes are larger and there is an increased rate of
transfer of melanin from melanocytes to keratinocytes.
| a person w/ darker skin does not have ↑ melanocytes Just more efficient
152
what color is Eumelanin pigment
black to brown
153
what color is pheomelanin pigment?
yellow to reddish
154
What are the Three major steps are involved in tanning
1. Photo-oxidation of melanin
2. Re-distribution of melanin granules to upper layers
3. Increased number of melanin granules
155
what are the resident
dendritic cells of the epidermis
Langerhans cells they play the role of macrophages
156
role of langerhans cells?
reside in the epidermis
Interact with T-cells to mount immune response
May also play a role in immune
tolerance
157
what are the hair growth phases
Anagen: active hair growth. Growth of the hair follicle and shaft; lasts 2-6 years
Catagen: reduced hair growth. Involution of the hair follicle; lasts 3 weeks
Telogen: resting phase; stays in involuted stage; lasts 2-4 months
158
what is important about the bulge of the hair follicle
Location of stem cells
Re-populate hair bulb after telogen phase
SC can migrate to epidermis for regeneration which can be helpful in burn situations
159
what happens in the matrix of the hair
Dividing epithelial cells
responsible for hair growth
160
how does the skin control of body temperature
-Activation of eccrine sweat glands
-Vasodilation of cutaneous blood vessels
-Arterio-venous anastomoses
161
what is the primary factor eliciting activation of eccrine sweat glands?
cholinergic innervation from the sympathetic nervous system
162
activating the Arterio-venous anastomoses does what to blood flow and temp
increases blood flow and dreases temp
163
Renault disease
characterized by dysfunctional regulation of blood flow in the extremities
164
Free nerve endings end in epidermis control what?
pain and temperature
165
Merkel cells in the stratum basale control what?
Light touch
166
Meissner corpuscle in dermal papilla control what
light touch and high frequency vibrations
167
Pacinian corpuscle in deep dermis control what
Deep pressure and vibration
168
Hair follicle mechanoreceptors control what?
hair movement
169
ruffini endings control what?
skin stretch
170
A severe burn that affects a relatively large portion of the integument will necessitate a skin graft. Which specific layer of the integument is critically involved in the renewal of the epidermis?
stratum basale
171
Skin patches can be used for the transdermal delivery of drugs. Which of the following molecules are most likely to cross the skin barrier?
slightly lipophilic
172
what are the layers of the epidermis from bottom up
stratum basale (the deepest portion of the epidermis), stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum (the most superficial portion of the epidermis)
173
what is the epithelial layer of the integument?
epidermis
174
what layers are the dermis divided into?
papillary layer and reticular layer
175
what is the hypodermis?
the layer depper than the dermis
rich in adipose tissue
176
dermal papille
extend from dermis inot epidermis for increased mechanical strength
177
interpapillary pegs
epidermis in between dermal papillae
178
which layer of the epidermis has desmosomal junctions?
stratum spinosum
179
which two layers are in thick skin and not thin skin?
stratuk granulosum(has keratohyalin granules) and strtum lucidum(has dying cells that still retain cytoplasm)
180
where are melanocytes mostly found
stratified squammous epithelia
181
what happens in vitiligo?
its an autoimmune disease where the immune sstem attacks the melanocytes
182
which cells are migratory within the skin epithelium?
melanocytes and langerhans cells
183
what cells are melanocytes derived from?
neural crest cells
184
what cells are langerhans cells dervied from?
HSC
185
what type of secretion does apocrine sweat glands develop?
merocrine
186
what is glabrous skin and where is it located?
hairless skin
located in the lips, soles of hands and feet, nipples, labiaminora, and penis
187
dermal papilla of the hair
a connective tissue elemetn that plays a role in organizing follicle development
188
arrector pili muscle
erect the hair
189
cutaneous horn
a hard keratinized secretion that may form pathologically over a site of localized trauma
190
First-degree burns
involve the epidermis. The burn site is red, painful, dry with no blisters. Mild sunburn is an example.
191
Second-degree burns
involve the epidermis and the most superficial part of the dermis. The burn site is red with blisters and may be swollen and painful.
192
Third-degree burns
involve the epidermis and the deep dermis. The burn site may appear white or charred.
193
Fourth degree burns
involve the epidermis, dermis and the underlying bones, muscles, and tendons. There is no sensation in the area because the nerve endings are destroyed.
194
Myofibroblast
-contractile single cells
-activated fibroblasts whith a basaphilic tail that is indicative of active ribosomes
-located in connective tissue
195
where are myofibroblast derived from
MSC-derived
196
where are myoepithelial cells derived from?
epithelium-derived
197
what is a myoepithelial cell?
-apical of basement membrane in epithelium
-smooth muscle that squeezes glands
198
what is the bodies reseverairor of extracellular Ca2+
bone
199
sarcoplasmic reticulum
basically the same as ER In muscle becomes
storage for Intracellular Compartment of Ca 2+
200
caveolae
take ih Calcium via endocytic vesicles
201
dense bodies in smooth muscle
anchoring sites for actin filaments, similar to the Z-disks in striated muscle
202
intermediate filaments in smooth muscle
internal net holds everything together
make of desmin or vimentin
203
reticular layer in smooth muscle
connective tissue fibers the smooth muscles pull on
204
smooth muscle is under what type of control
involuntary
205
how do smooth muscle cells contract
Free intracellular myosin pulls against f-actin that is tethered (via a-actinin) to dense bodies, which can be membrane-bound
206
what neurotransmitter is used for the sympathetic division?
epinephrine
207
what neurotransmitter is used for the parasympathetic division?
acetylcholine
208
how is smooth muscle divided?
myogenic(single-unit) or neurogenic (multi-unit)
209
myogenic smooth muscle
one axon -> many cells
*many gap junctions
*coordinated action
*responsive to hormones, etc.
210
neurogenic smooth muscle
*one axon -> few cells
*independent action
*found in iris, arrector pili, large
vessels, small airways of lung
211
what are these structures and what are they transporting?
caveolae thransporting Ca2+
212
what is the size difference of the three kinds of muscle cells
smooth muscle is the smallest, then cardiac muscle, and skeletal muscle is the largest
213
what are dyads
present in cardiac myocyte in the Z-line of the sarcomer
214
what are dyads
present in cardiac myocyte in the Z-line of the sarcomer
215
what is an intercalated disk?
where twho cells adhere to each other using fascia adherens
216
What is present in skeletal but not cardiac muscle
a perimysium
217
which muscle is a syncicium?
skeletal muscle
218
what muscle has A and I bands?
both skeletal and smooth muscle
219
what muscle has A and I bands?
both skeletal and smooth muscle
220
what kind of tissue is this?
cardiac muscle
221
what are the distictive features of cardiac muscle cells
one, sometimes two, nuclei per cell
cells (cardiac myocytes) may be branched
*striated; striations more delicate than skeletal fibers
*many mitochondria and fewer myofibrils
*sarcoplasmic cone- Thick + thin titi merits must bend out o f the way .
*intercalated disc
222
what structure is this pointing to?
Intercalated disc
A distinct irregular band oriented perpendicular to the cell’s long axis
223
what are the three intercellular junctions in the intercalated disk?
fascia adherens, gap junction, and desmosomes
224
Myocardial Endocrine Cell
Most are located in atria of heart
Relases granules that signal
225
Atrial Natriuretic Protein(ANP)
-relseased from Myocardial Endocrine Cell
-released in response to
stretch of atrial wall
-ANP promotes loss of sodium, potassium and water in kidneys;
reduces body fluid and lowers blood pressure.
226
what is circled
Myocardial Endocrine Cell
with Granules of ANP in cell
227
what is circled?
Purkinje fibers
228
what is a purkinje fiber?
Cardiac cells modified for
conducting electrical signals
229
How does a cardiac signal travel?
SA node -> AV node ->
Bundle of His -> Purkinje fibers - > ventricular fibers
230
what is this structure and where is it?
purkinje fbers in subendocardial layer
231
triads
in skeletal muscle at the A and I band interface
where 2 sarcoplamic recticulum and 1 t-tublue meet
232
what is the mitochondrial count in skeletal muscle comparativly
high mitochondria count
233
Type 1 skeletal muscle fibers
red
slow-twitch, oxidative; Capable of repeated
contraction without fatigue
234
type IIA skeletal muscle fibers
intermediate
fast-twitch, glycolytic-oxidative; Fatigue-resistant
235
type IIB skeletal muscle fibers
white
fast-twitch, glycolytic; Strong and fast, fatigues
easily
236
can the different muscle types interconvert?
white can convert to interconvert to intermediate and red can conterconvert to intermediate but red and white cant interconvert
237
how can we tell the difference between the different types of skeletal muscle
use a stain for glycolytic or oxidative prcesses
238
what stain stains for white musle
must stain for glycolytic processes
-PAS stain
-white will have the most glycogen and red will have the least glycogen
239
what stains for red muscle?
-needs to stain for oxydative processes
-cytochrome oxidase(a mitochondrial enzyme)
-red will stain darkest because it has the most midochondrial activity
240
developmentally where does skeletal muscle come from?
Myotome
241
roles of dermatome and myotome in the adult
they refer to the mapping of innervation and muscles to the spinal cord roots from which they arise.
242
how do skeletal muscles develop?
1) A skeletal muscle fiber is a syncytium of myoblasts.
2) Primary myotubes form from the fusion of myoblasts.
3) Secondary myotubes form within the external membrane of the primary myotubes, and subsequently separate to form additional fibers of equivalent adult morphology
4) Myoblasts persist beneath the external membrane of adult fibers as satellite cells
243
what cell is this
myo-satellite cell
A population of undifferentiated, quiescent precursors that become activated to divide and differentiate in response to the demands of growth and damage.
| muscle stem cell
244
How many cell progenerter types are in skeletal muscle?
2
245
junctional folds
because a skeletal muscle fiber is so
large, it needs a specialized structure to depolarize its membrane.
| specialized synapse at the neuromuscular junction
246
muscle spindle
sits in parallel with the body of the muscle
senses degree of muscle elongation(length)
247
Golgi tendon organ
sits in serial arrangement, between muscle and tendon
senses the degree of tension(force)
248
what is the Morphology of the Muscle Spindle
The muscle spindle contains bag and chain fibers (not usually morphologically distinguishable), each sensitive to different ranges of stretch.
It both receives efferent (gamma motor neurons) and generates afferent (type Ia & II sensory) innervation.
It is surrounded by a capsule, that is the equivalent of perimysium.
249
epimysium
CT around while muscle
250
perimysium
CT around muscle fasicle
| 1
251
endomysium
CT around muscle fiber
| 2
252
Desmin
connects myofibrils with each other at Z-line, holding them in register
253
Costamere
collection of intracellular proteins binding desmin to sarcolemma at
the z-line.
254
Mutations in the costamere-associated protein dystrophin are implicated in
muscular dystrophies
255
Myotendinous junction
actin filaments are directly anchored to the cell membrane in a structure similar to the fascia adherens.
256
what is skeletal muscle repair dependent on?
the external membrane must be intact
257
what is the evolutionarily oldest form of muscle?
smooth muscle
258
what binds actin to the Z line?
nebulin
259
what is in the A band of muscle?
myosin
260
What is in the I band of muscle?
actin/thin filments
261
H-band
The pale H-band is formed by the absence of actin at the center of the sarcomere
| just thick filments
262
Myokines
When active, skeletal muscle secretes cytokines that affect its function,[1] and these are receiving increased attention as direct health benefits of exercise
263
IL-6
the first discovered myokine: normally pro-inflammatory, but anti-inflammatory when secreted by muscle
264
gamma motor neurons
innervate the bag and chain fibers in order to alter their sensitivity
265
what is the function of dyad and triad
The dyad and triad are specializations to allow the electrical impulse across the cell membrane to act more quickly on the SR membrane
266
what are the 4 parts of the spinal cord?
Cervical
Thoracic
Lumbar
Sacral
267
label spinal cord directions
268
label brain directions
269
label lobes
270
What makes up the Cerebral Cortex
Includes cerebral hemispheres and basal ganglia, amygdala and hippocampus
271
what are the parts of the brain stem?
midbrain pons and medulla oblongata
272
what are the Subcortical Structures involved in
homeostasis & temp
Controls Vicera + hormones+ sleep
" primitive part of brain "
| brainstem
273
what do the Meninges do?
Cover brain and spinal cord
serve as protection
274
what are the mening layers
Dura mater (outer layer)
Arachnoid Mater (middle layer)
Pia Mater (inner, attached to surface of brain)
275
what is the Dura mater and what are the layers?
Tough, fibrous outer covering, with an external periosteal layer and internal meningeal layer.
276
what are the dura's two specialized roles?
1. Dural Infoldings
2. Dural Venous Sinuses
277
Dural Venous Sinuses
between 2 layers for drainage of deoxygenated blood
thhe CSF also draisn in the venous sinuses
278
Emissary Veins
Veins that drain the scalp
279
Diploic Veins
Brain Bone veins
280
Dural Infolding
divides major parts of the brain
281
Arachnoid mater
-middle meninges layer
-Thin, web-like middle layer.
- Covers the subarachnoid space which contains cerebrospinal
fluid (CSF), arteries and veins
282
Pia Mater
-The deepest layer of the meninges. Has thinner, shiny surface.
-Adheres directly to the surface of the brain and follows every curve (sulcus) of the cortex.
-Covers brain grooves
283
label
284
what are the two major sources of blood supple to the brain?
common carotid and vertebral artery
285
Extra-Axial Brain Hemorrhage
Intracranial bleeding can be outside the brain tissue (extra-axial) or inside the brain tissue (intra-axial)
286
Epidural Hematoma
Most cases occur from meningeal artery ruptures from skull fractures. The blood pools between the skull and dura and is confined by periosteal sutures
-The diva has it's own blood supply , if you rupture
one of these arteries , pooling In a space where expansion is not possible
287
symptoms of a epidural hematoma
Symptoms typically include: Lucid interval followed by loss of consciousness, severe headaches, confusion, dizziness, vomiting
288
Subdural Hematoma
Venous hematoma involving the rupture of bridging veins (cerebral veins that are draining into the venous sinuses). Located in the potential space between the dura and arachnoid mater.
| blood pooling from Venus
system; Veins that drain brain
289
what population is most susceptible to a Chronic Subdural Hematoma
Mostly occurs in the elderly population even with minor injury.
b/c brain shrinks & there is more space for collision
290
symptoms of a subdural hematoma
Headache, hemiparesis, seizures, visual changes, nausea or vomiting, lowered state of consciousness
291
Subarachnoid Hematoma
Most commonly associated with a ruptured cerebral aneurysm. Arterial blood fills the subarachnoid space and other spaces normally occupied by CSF
| Post injury the subarachnoid space can fill with blood from rupture
292
Subarachnoid Hematoma symptoms
Sudden onset “thunderclap” headaches, dizziness, confusion, hemiparesis, visual changes, nausea or vomiting, lowered state of consciousness
293
How does the CNS communicate with the body?
Tracts/Pathways that are a bundle of axons that travel from one nuclei to another. Pathways that exit the CNS are what we know as spinal nerves or cranial nerves.
294
Cranial Nerves are part of which system?
Peripheral Nervous System
295
What is the job of the Spinal Cord?
-Provides sensory information to reach the brain
-Provides motor information to influence movement
-Contains motor neurons which directly control muscles
296
what are the vertebrae from top down and how many vertebrae does each have?
297
how many nerves does each vertebrae have?
298
where are the vertebral enlargements?
Cervical + lumbar enlargement - more info coming in
- more Input + output
299
The ratio of white matter to gray matter increases is what way?
from caudal to rostral
300
label using anterior and posterior references
301
what are the Glial cells?
Astrocytes, Oligodendrocytes, Microglia, Schwann Cells, Satellite cells
| supporting cells
302
How many synapses does a single neuron receive?
thousands
303
what is the Basic cellular unit of the Neurvous system?
neuron
304
Dendrite
receives informationfrom other neurons via synapses and carries the signal towards the soma
305
Soma(cell body)
supportsthe metabolic and synthetic needs of the neuron; integrates electrical signals (though final integration occurs at axon hillock)
306
Axon
conducts information away from the cell body via an electrical signal called an action potential
307
what are the neuron types?
Pseudounipolar
Bipolar
Multipolar
308
Pseudounipolar neuron
this type of neuron contains an axon that has split into two branches; one branch travels to the peripheral nervous system and the other to the central nervous system.
| sensory
synapse at the spinal cord
309
Bipolar neuron
a type of neuron that has two extensions (one axon and one dendrite). Many bipolar cells are specialized sensory neurons for the transmission of sense. As such, they are part of the sensory pathways for smell, sight, taste, hearing, touch, balance and proprioception.
310
Multipolar neuron
-A multipolar neuron is a type of neuron that possesses a single axon and many dendrites (and dendritic branches), allowing for the integration of a great deal of information from other neurons.
-motor neurons
311
describe the morphology of sensory neurons and some examples of where you could find them?
-morphology:
central nucleus
ring of satellite cells
-synapses do not occur
-examples:
-dorsal root ganglion
-cranial sensory nerve ganglia
312
describe the morphology of motor neurons and some examples of where you could find them?
-examples:
-ventral horn of spinal cord -Autonomic ganglia
-multipolar neurons
-morphology:
eccentric nucleus dispersed satellite cells
-synapses are abundant
-larger & more spread appoint
313
Afferent (sensory) nerve fibers
carry information from sensory receptors in the skin (ie. touch, temperature, pain) toward the CNS
314
Efferent (motor) nerve fibers
carry information to the periphery to innervate skeletal muscles
315
Label the connective tissue parts of the nervous system
316
which nerves are commonly myleinated and which are unmylienated?
Voluntary skeletal muscle mylenated
Autonomic nervous system unmylenated
317
# label
318
what are the 3 Subdivisions of the ANS and what does each do?
Sympathetic
-Mobilizes the body for action in stressful and dangerous situations o The “fight or flight” system
Parasympathetic
- Regulates the body’s functions to conserve energy
-”Rest and digest” system
Enteric
-In the wall of the GI tract and is important for GI motility
319
how is the Sympathetic neuron chain?
* Cell bodies of pre-synaptic neurons are found in the (paired) intermediolateral cell columns of the spinal cord
* Cell bodies of the post-synaptic neurons are found in the para- vertebral ganglia (sympathetic chain)
| 2 neuron pathway
320
Blank nucleus refers to?
collection of cell bodies in CNS
321
Ganglia refers to
collection of cell bodies in PNS
322
Tracts refer to
collection of axons in the CNS
323
nerves refers to
collections of axons in the PNS
324
how is the parasympathetic neuron chain?
Presynaptic parasympathetic neuron cell bodies are located in:
– Gray matter of the brainstem
– Gray matter of the sacral segments of the spinal cord
-2 neurons but longer pre ganglia
-ganglia closer to targets
325
What leads to specification of the neural tube
Molecular factors from the ectoderm and notochord control the development of zones of the neural tube
326
SHH (sonic hedgehog)
a “ventralizing” neurotube factor
327
BMP4 & 7
dorsalizing factors
328
What does the neural tube differentiates into?
alar (roof) plate and basal (floor) plate
| using molecular gradients
329
what do the neural tube roof structure differentiate into?
cerebellum, cortex
330
what do the neural tube floor structure differentiate into?
brainstem and thalamus
331
From front to back, the neural tube is segmented into:
prosencephalon
mesencephalon
rhombencephalon
332
how does the floor plate develop and what does it give rise to?
The ganglionic eminences develop laterally on the floor plate - these disappear as they give rise to: thalamic radiations,
basal ganglia, and
inhibitory neurons of cortex
333
how does the prosencephalon develop and what does it develop into?
prosencephalon (telencephalon) is expanding radially (into layers) and laterally (into areas) into the cerebral cortex.
334
excitatory vs inhibitory neurons of the cortex migration
excitatory are born in the floor plate & stay here
inhibitory neurons are born in the floor plate and migrate
335
what represents the largest radiation of animalia?
Protostomes
336
what represents the most recent radiation in development?
Deuterostomes
337
when did Endochondral ossification develop?
in fish
338
what differeitates mammals
mammary glands, placenta, and live born
339
how many mass extinctions have there been?
5
in the 6th right now
340
in protostomes what forms first
mouth forms first
341
In deuterostomes what forms first
anus
| we are deuterosomes
342
what animals are protostomes?
worms
insects
butterflies
343
chordate
has a notochord present but no vertebre
344
craniate
has a hard skull
345
vertebrate
hard backbone
346
agnatha
jawless vertebrates
347
gnathostomata
hinged jaw
348
what is a Non-vertebrate craniate example
Sea Lamprey
349
why are some brain areas bigger in some animals than others?
The religions of the brain specialize and grow based
on the needs of the animal and envirment
350
what happens in the superior colliculus
visual processing region
351
what happens in the inferior colliculus
auditory processing region
352
where are brocas area and wernicke's area?
unilateral
95% of ppl have them on the left side
353
what is grey and what is white matter
354
grey matter represents what part of the neuron
cell body
355
white matter represents what part of the neuron?
axons
356
what areas are mylienated first?
Primary sensory areas are myleinated first
357
gyrencephalic
highly folded cortex
ex: dolphins
358
lissencephalic
smooth brain
ex: manatee
359
how does degree of folding affect the brain
degree of folding does not matter in the brain
360
what type of cell is this?
astrocyte
361
Astrocyte
-primary structural cell
-end-feet on vasculature are part of BBB
-mediates ionic milieu of ECF
-Controls nutrition and metabolism
362
Alzheimer’s disease
characterized by accumulation of Aβ plaques extracellularly
363
Parkinson’s disease
resting tremor and inability to initiate movements - loss of
dopamine synthesizing neurons in the substantia nigra
364
Huntington’s disease
uncontrollable ‘chorea’
| a neurological disorder characterized by jerky involuntary movements
365
how is the primary cilium related the the three most common neurological diseases?
Astrocytes have primary cilia (9+0), used to sense their environment & determine reactivity.
All three major diseases show altered primary cilium function.
366
Oligodendrocyte
myelinates axons in the CNS
homologous (but not identical to) peripheral Schwann cells
| contribute to multiple axons
367
Schwann cells
myelinates axons in PNS
| myelinates 1 axon
368
Microglial Cell
macrophage of CNS
derived from monocyte progenitors enters brain during development
369
how can microglia be an indicator of disease?
Microglia have an ‘activated’ state, which can be used as a marker of pathologies
370
Golgi stain
a type of silver stain – in which only 1 out of every 1000 or so neurons is stained. Today, we still don’t know why this happens
| help us better visualize the neurons
371
what are the are three major categories of cells in then brain?
non-neuronal cells (glia) excitatory neurons inhibitory neurons
372
excitatory vs inhibitory neuron morphology
-each functional area also has excitatory neuron types that are unique to that area.
-Inhibitory neurons types are more homogenous across the cortical sheet
373
how do cell types segragate in the brain?
Cell types segregate by general anatomical position within the cortical sheet and cortical layer
374
excitatory vs inhibatory neuron differences
-Excitatory neurons have well-defined dendritic trees, with long axons.
-Inhibitory neurons have local, diffuse arborizations
375
how do excitatory and inhibitory neurons work together
excitation gets tampered down by local inhibition until there is enough excitation to cause a signal
376
glutamate
major excitatory neurotransmitter of cortex
377
GABA
major inhibitory neurotransmitter of cortex
378
what are ionotropic receptors and which neurotranmitters use them?
receptor is the channel
glutamate, GABA, and ACH use
| fast
379
what are metabotropic receptors and which neurotranmitters use them?
receptopr signals a G-protien coupled mechanism
dopamine
serotonin
norepinephrine
epinephrine
380
how does the cortex develop?
symmetric division expands the sheet
asymmetric division thickens the sheet
| neurons migrate through the cortical sheet along “radial glia”
381
where are neurons born?
ventricular zone
382
how does the cortext grow?
Cortex grows radially from cells that enter the sub-ventricular zone
383
how many layers does the adult cortex have?
In the adult, cortex has between 3-6 defined layers based on cytoarchitecture & connectivity
384
do birds have cortical layers?
Birds lack genes that are critical for forming layers
385
Disorders of inhibitory migration may lead to?
epilepsy
386
How are Inhibitory Neurons developed?
nhibitory neurons migrate in a tangential direction across the cortical surface from subpallial (ventricular floor) areas through the cortical sheet.
387
what are the layer surrounding a blood vessel in the brain?
blood
endothelium
basement membrane
pia mater
pericyte
basement membrane
foot process of astrocyte
neuron
388
where are tigh junction located in the BBB?
endothelium wall is continuous with tight junctions, and has the major responsibility (in humans) for the BBB
389
How is Lipid entry into the brain mediated
by endothelial cells
Intracellularly-bound lipids are shed to the circulation in exosomes.
390
Interventricular foramen
connection of lateral to third ventricles
391
Cerebral aqueduct
connection of third to fourth ventricle
392
what kind of cells are these?
Ependymal cells
393
Ependymal cells
ciliated, simple cuboidal or columnar epithelium lining ventricles
produces, absorbs, moves CSF
394
Hydrocephalus
overproduction of fluid
occlusion of aqueducts
poor absorption (back to blood)
395
what is this structure
central canal
396
what is the central cannal?
lined with ependymal cells filled with CSF
397
what are the Two Circulations in the Brain and what does eachh do?
cerebrospinal fluid (CSF) formed at the choroid plexusdrained at the arachnoid
interstitial fluid (ISF)
filtrate of plasma at arterioles drains to capillaries
398
glymphatic system
control of ISF flow between
the arterial & venous Virchow-Robin spaces by
glial cells
| mimics lympatic system
399
Nissl bodies
Cell bodies of neurons may sometimes be recognized in LM by the presence of Nissl bodies, representing large amounts of basophilic ER
400
axosomatic or axoaxonal
Synapses on portions of the cell other than the dendrite
401
bouton en passant
Presynaptic elements along the length of the axon
402
how is myelin formed
Myelin is formed when a supporting cell wraps its cytoplasm around an axonal process numerous times.
403
what does the rhombencephalon differetiate into
myelencephalon - medulla. Its lumen becomes the caudal portion of the fourth ventricle.
metencephalon - pons, cerebellum. Its lumen becomes the rostral portion of the fourth ventricle.
404
what does the prosencephalon differentiate into?
diencephalon - thalamus, hypothalamus, (epithalamus, subthalamus) optic nerve & retina, posterior pituitary, pineal gland. Its lumen becomes the third ventricle.
telencephalon - cerebral cortex, basal ganglia, hippocampus, amygdala, olfactory bulb. Its lumen becomes the lateral ventricles
405
dermatome
Each spinal nerve innervates a particular region or “level” of the body
406
photoreceptors (rods and cones)
Photoreceptors are specialized neurons found in the retina that convert light into electrical signals that stimulate physiological processes. Signals from the photoreceptors are sent through the optic nerve to the brain for processing.
407
bipolar cells
Bipolar cells are one of the main retinal interneurons and provide the main pathways from photoreceptors to ganglion cells
408
ganglion cells
Ganglion cells are the projection neurons of the vertebrate retina, conveying information from other retinal neurons to the rest of the brain.
409
horizontal cells
Horizontal cells are the laterally interconnecting neurons having cell bodies in the inner nuclear layer of the retina of vertebrate eyes.
410
amacrine cells
Amacrine cells are the intrinsic interneurons of the inner retina representing the most diverse class of neurons in the retina.
411
Müller (glial) cells
Müller glia are the major glial component of the retina. maintenance of the blood-retinal barrier, local phagocytosis, and scaffolding of the neural circuitry during development.
412
what are the Layers of the retina
● photoreceptor layer (rod and cone outer segments)
● external limiting membrane (terminal bars between Müller cells and photoreceptors)
● outer nuclear layer (rod and cone inner segments)
● outer plexiform layer (photoreceptor-bipolar-horizontal synapses
● inner nuclear layer (bipolar, horizontal, amacrine and Müller cell bodies)
● inner plexiform layer (ganglion-bipolar-amacrine synapses)
● ganglion cell layer (cell bodies)
● nerve fiber layer (axons of ganglion cells)
● internal limiting membrane (basement membrane against the vitreous)
413
label
414
what are the specific photopigments?
rhodopsin and cone-opsins
415
what are the three types of cones
S (short), M (medium) and L (long) describing the wavelengths of light to which they are optimally receptive. They are colloquially known respectively as blue, green and red cones
416
What are the two types of neurons mediate communication across the surface of the retina
horizontal cell and amacrine cell
417
which are more sensitive rods or cones?
rods
418
which system has better spatial acuity?
cones
419
which are in the fovea rods or cones?
L and M cones
420
where do rods dominate?
in the parafoveal regions
421
what is the thickest part of the retina?
The parafoveal region is the thickest part of the retina
422
what is the macula
the foveal and parafoveal reigion together
423
how does the retina get nutrition?
Retinal vessels enter and exit with the optic nerve, and branch over the inner surface of the retina
The second source is the choriocapillaris, the vasculature of the choroid layer, deep to the outer neural retina. This is the primary source of oxygen for the photoreceptors, the layer with the highest intrinsic energy requirements.
424
glaucoma
increased fluid pressure in anterior and posterior chambers is transmitted through the vitreous and first affects ganglion cells.
425
diabetic retinopathy
leakage of capillary endothelia and concomitant breakdown of the blood-retinal-barrier caused by glycemic stress selectively kills photoreceptors
426
age-related macular degeneration
typically affect central photoreceptors, usually starts as a dry form caused by pathological deposits (“drusen”) in the vicinity of Bruch’s membrane, and may progress to a wet form in which new vasculature grows in the choroid, producing local dislocations of the layer that result in blurred vision and cellular damage. In advanced cases, these vessels may grow through the RPE layer.
