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MSK week 1 SGU

Terms in this set (176)

cell type of epidermis
stratified squamous epithelium
Cell type of dermis
Two layers - loose connective tissue followed by dense irregular connective tissue
Thin skin only epithelial skin appendages
hair, hair follicles and Sebaceous glands
stratum corneum
outermost layer of the epidermis, which consists of flattened, keratinized cells.
no organelles
keratin filaments aggregated into tonofibrils
variable in number of layers- determines which vs thin skin
stratum lucidum
only in thick skin
Considered a subdivision of the
stratum corneum
stratum granulosum
3rd layer of the epidermis, Contain conspicuous granules which is made up of Keratohyalin granules and lamellar bodies
Keratohyalin granules
irregularly shaped, variably sized
Cystine-andhistidine-rich proteins = precursor for filaggrin
Responsible for aggregating the keratin filaments
within the cornified cells
stratum spinosum
prickle layer
Adjacent cells are connected to each other via desmosomes =slight thickening known as the node of bizzozero
most superficial layer- Nuclei become elongated instead of ovoid
freely moving Langerhans cells found predominantly in this layer
stratum basale
the deepest layer of the epidermis (rest on basal lamina attached by hemidesmosome) consisting of a single layer of cuboidal cells acting as stem cells capable of undergoing cell division to form new cells
Contains many melanin granules
Lots of cell junctions- desmosomes
basal cell carcinoma
Most common and least severe type of skin cancer caused by UV light
Cells at the periphery has a characteristic palisaded appearance
It invades the dermis and deeper lying structures doesn't typically metastasize
Bullous pemphigoid
Damage to Hemidesmosomes - separation of epithelium from the dermis
IgG attack hemidesmosomes that bind to basement membrane and stimulate leukocytic infiltration
large blisters that don't easily rupture
squamous cell carcinoma
Malignant tumor of keratinocytes (inactive p53)
Hyperkeratosis and parakeratosis
Common in fair skinned older people
Develop formation of squamous pearls or swirls
Pemphigus vulgaris
Desmosomes (Antibodies target cadherins and desmoplakins) - separation of the stratum spinosum cells from one another. Atrophy of the prickle cell layer.
easy to rupture blisters
Nikolsky's sign
easy to rupture blisters. sign of Pemphigus vulgaris
Lamellar bodies formation
Formed by the Golgi apparatus of the spinosum cells
Contents excreted by exocytosis
second degree burn
Partial thickness epidermis and dermis epithelial water barrier disrupted Heals spontaneously
third degree burn
ull thickness epidermis, dermis and subcutaneous tissue
Water barrier disrupted, nerves and blood vessels destroyed Does not heal spontaneously, fluid loss is extensive
first degree burn
Partial thickness epidermis only Heals spontaneously
Hyperkeratosis
hyperplasia of the horny layer (stratum corneum) of the skin (or the cornea)
-psoriasis
Parakeratosis
retention of nuclei in the stratum corneum of the skin
-psoriasis
Acantholysis
loss of intercellular connections resulting in loss of cohesion between keratinocytes
-Pemphigus vulgaris
Acanthosis
epidermal hyperplasia (S. spinosum)
-Acanthosis nigricans
Psoriasis
a chronic inflammatory and proliferative disorder of the skin clinically manifested as well-circumscribed
erythematous plaques covered with silvery scales
Nails
Hard plates of epidermal keratinized cells
Dermis
Contains many of the epidermal appendages, nerve corpuscles, and glands
Contains the smooth muscle cells that move the hairs
pilosebaceous organ
hair follicle, sebaceous gland, and smooth muscle
hair follicle
thin skin only,
Bulb (has Melanocyte stem cells) contains the matrix cells for hair formation
Hair formation
-Matrix cells contribute to formation of the internal root sheath and the hair shaft
-matrix cells undergo keratinization in keratinization zone
-fully keratinized hair is separated from the underlying dermis via a thick basal lamina
sebaceous glands
Simple branched acing that secretes holocrine
Sebum product helps prevent the hairs from becoming dry and brittle
Secretory portion is located in the deeper dermis
acne
inflammatory disease of the skin involving the sebaceous glands and hair follicles
eccrine sweat glands
Simple coiled tubular glands
Secretory portion is in the deep dermis, merocrine secretion
Composed of stratified cuboidal epithelium consisting of a basal layer and a luminal layer
Apocrine glands
Found only in armpit and perineum
Coiled tubular glands
Secrete pheromones
Ducts are straight and lined by simple cuboidal
opens into hair follicle
Secretion mode is merocrine
Secretory lumen larger than eccrine sweat glands
free nerve endings
respond to pain, fine touch, and temperature
Most numerous and terminate in the stratum granulosum
no myelin or connective tissue
Pacinian corpuscles
respond to deep pressure and vibration
Composed of a myelinated nerve ending surrounded by a capsule structure. myelin gone when enter capsule. unmyelinated portion is covered by a series of tightly packed, flattened Schwann cell lamellae that form the inner core of the corpuscle
Meisner's corpuscles
-receptors in skin that respond to touch and low frequency stimuli
-There are one or two unmyelinated nerve endings of myelinated nerve fibers follow spiral paths in the corpuscle
-The cellular component consist of flattened Schwann cells that form several irregular lamellae through which the axons course to the pole of the corpuscle
Ruffini's
The axonal endings (dispersed and intertwined inside the capsule) respond to displacement of the collagen fibers so they respond to stretch and torque
Collagen fibers from surrounding connective tissue pass through the capsule
epidermal wound healing
occurs following superficial wounds that affect only the epidermis
-basal cells of the epidermis surround the wound, break contact with the basement membrane, enlarge and migrate across the woundfrom opposite sides until they meet. new cells divide to thicken the new epithelium
deep wound healing
occurs when an injury extends to the dermis. healing occurs in 4 phases-
Inflammatory Phase (blood clot formed)
Migratory Phase (clot to scab and fibroblasts form scar tissue)
Proliferative Phase (random growth of epithelial tissue)
Maturation Phase (scab off, fibrosis scar formed)
Skin color produced by
ratio between Eumelanin and Pheomelanin determine skin color and hair color
-Light skinned individuals have their melanin concentrated in the stratum basale
-Dark skinned individuals have the pigment dispersed throughout the basale and
spinosum layers
-Melanin production is influenced by the surrounding keratinocytes in response to UV radiation
Albinism
Autosomal Recessive ,characterized by a partial or total lack of melanin pigment (particularly in the eyes, skin, and hair). Lack of tyrosinase
• Types: Ocular + Oculocutaneous
vitiligo
autoimmune destruction of melanocytes in areas of the skin produces white patches
Types: Focal, Segmental, Generalized
malignant melanoma
Malignant transformation of melanocytes
May invade the dermis - metastases - fatal
Use ABCDE
Keratinocytes
Attached to each other by desmosomes and to basal lamina by hemidesmosomes
produce lamellar bodies and keratins
Regulated by proteolytic activity on the desmosomes
Melanocytes
neural crest derived
Replicate more than keratinocytes
Produce melanin that is transferred to surrounding keratinocytes via Cytocrine secretion
Tyrosine= precursor for melanin
Merkel's cells
Least numerous
Detect touch sensations (abundant in fingertips)
cytoplasm contains neurosecretory granules
Closely associated with the expanded terminal bulb of afferent myelinated nerve fibres = Merkle's corpuscle
Langerhans cells
special macrophages that serve as antigen-presenting cells in the skin
No desmosomal junctions
Involved in delayed-type hypersensitivity reactions
Have birbeck granules
Dermis Papillary layer
Predominately type I and III collagen fibers
Loose connective tissue
Contains Meissner corpuscles
Contains blood vessels (we know that the epidermis is avascular)
elastic fibers are threadlike and form an irregular network
Dermis Reticular layer
thick irregular bundles of mostly type I collagen and courser elastic fibers
Dense irregular connective tissue (less cells)
Hypodermis
Aso called a subcutaneous layer, this is a layer of *fat located under the dermis of the skin. The hypodermis is a major energy storage site and also provides insulation for the body
Hair follicles, glands and mechanoreceptors extend into this layer
What makes fingerprints?
dermal papillae and epidermal ridges or rete ridges
osteoprogenitor (osteogenic) cells
precursor to osteoblasts
derived from embryonic mesenchyme stem cells
found in the periosteum and endosteum or both mature and immature bone
Osteoblasts
bone-building cells that secrete matrix (osteoid)
Entrapped in lacunae & Cytoplasmic Processes extend to caniliculi
Components of osteoid
- Calcium binding protein( osteonectin and osteocalcin)
- Multiadhesive glycoproteins
- Alkaline phosphatase - Proteoglycans
Osteocytes
a mature bone cell, formed when an osteoblast becomes embedded in the matrix it has secreted.
occupy Lacunae (empty space)
live for 10 - 30 years
respond to mechanical forces applied to the bone by initiating bone formation or Osteocytic remodeling
derived from the fusion of blood-derived
mononuclear hemopoietic stem cells form the granulocyte- macrophage lineage.
Osteoclasts
Derived from monocytes. Bone reabsorption.
abundant lysosomes
multinucleated giant cells which can have as much as 50 nuclei
bone lining cells
not actively remodeling
little cytoplasm and few organelles
Cytoplasmic processes which contact via gap junctions with each other and with osteocyte processes in adjacent canaliculi
Example- endosteal and Periosteal
Howship's lacunae
"bay" or depressions on the bone surface during the process of remodeling where osteoclasts are
3 types of cartilage and histogenesis
hyaline, elastic, fibrocartilage
histo- Mesenchyme
Hyaline cartilage location and function
Nose, Costal cartilages, Laryngeal Tracheal/bronchial rings, Articular surfaces of long bones, Epiphysial Growth Plate, Fetal Skeleton
Supportive, Cushioning, Shock Absorber, Growth Plate, Model for Bone Formation
Elastic cartilage location and function
Pinna of Ear, Auditory Canal, Eustachian Tube, epiglottis
Provide support with flexibility
Fibrocartilage location and function
Intervertebral disc, Pubic symphysis, Medial/lateral menisci,i Attachment of ligament to bone,
Intersections of some tendons and ligaments, Articular discs
Flexibility
Hyaline and Elastic Cartilage cells
Chondroblasts (synthesize cartilage matrix) /chondrocytes (isogenous groups, 4-8 cells, (cell nest))
Fibrocartilage cell type
Fibroblasts transform to chondrocytes under stress
hyaline cartilage ECM and calcification
Type II/GAGs/Glycoproteins
Calcifies-bone formation and aging
Elastic cartilage ECM and calcification
Type II/ GAGs/ Glycoproteins/ELASTIC FIBERS in addition
Never calcifies
Fibrocartilage ECM
Predominantly Type I/some Type II/GAGs (dermatan and chondroitin sulphate)
Hyaline and Elastic cartilage growth
appositional and interstitial
Fibrocartilage cartilage growth
Interstitial only due to absence of perichondrium
Hyaline cartilage degeneration and regeneration
Does not readily degenerate
Poor, perichondrium forms scar tissue
Elastic cartilage degeneration
Does not readily degenerate
Elastic and hyaline cartilage matrix
Avascular
Nutrients supplied by vessels from perichondrium
Contains a lot of GAGs
A lot of proteoglycans that provide immense strength
Fibrocartilage matrix
Contains Type I and II collagen fibers
Organic portion of bone
Mainly Type 1 Collagen
90% total weight of matrix proteins
Ground Substance: Proteoglycans, Glycoproteins, Growth Factor, Cytokines
Inorganic portion on bone
50% of dry weight of proteins
Mainly Calcium Phosphate in form of Hydroxyapatite
Trace minerals- Bicarbonate, Citrate, Magnesium
immature or woven bone
-Found in the developing fetus, remodeling sites and alveolar sockets of adults
-Non- lamellar
-Increased cellularity
-More ground substance and randomly arranged collagen fibers
-Remodeled and replaced by mature bone
Mature bone
-Forms the majority of the adult skeleton
-Has a regular arrangement of collagen and cells within the calcified matrix
-Mature bone tissue cells and matrix are organized as lamellae
-Very resilient
compact bone
Arranged in cylindrical Osteons or Haversian systems
Have Haversian canals, Volkman's canals, and Lamella
Haversian canals
vascular canals (blood vessels, lymph vessels, nerves travel through) in bone that are not found in parallel array since bone is always being remodeled
Volkmann's canals
connect Haversian canals to periosteum and endosteal marrow cavity
are not found in parallel array since bone is always being remodeled
Lamellae
multiple parallel arrays of collagen fiber that have alternating directions to provide strength
-4 types= concentric, inner circumferential, butter circumferential, interstitial
Outer & inner circumferential lamellae
-Deep to the periosteum the lamellae are arranged in concentric rings - outer circumferential lamellae
- Similar arrangement of lamellae can be found next to the endosteum - inner circumferential lamellae
interstitial lamellae
Remnants of old remodeled osteons between newly laid down osteons
three major regions of osteoclast
1) Ruffled Border: Fingerlike Invaginations around Howship's Lacune Active Bone Resorption
2) Clear Zone: attach Microfilament to boney surface
3) Basal Region: House organelles and nuclei
spongy bone
trabecular bon- within 1= concentric lamellae with osteocytes in lacunae connected via canaliculi
No canals containing blood vessels, lymphs or nerves
Endosteum
non-calcified vascular connective tissue layer covering internal surfaces of bone
-examples: Marrow cavities, inner lining of cortex, Haversian and Volkmann's canals
Composed of single layer of Endosteal cells- Osteoprogenitor cell which differentiates into osteoblast and Bone-lining cells
Periosteum
non-calcified vascular connective tissue layer covering external surfaces of bone, except over articular surfaces
Has 2 layers- Outer fibrous layer and Inner cellular layer(contains osteoprogenitor cell and bone lining periosteal cell)
Cruciate ligament
hold dens in place during rotation of the head
Apical ligament
is deep to the cruciate ligament, attaching the dens to the skull.
Alar ligaments
laterally From dens to skull
transverse ligament of atlas
thick, strong band, which arches across the ring of the atlas, and retains the odontoid process in contact with the atlas
part of the cruciate ligament
kyphosis
It is an abnormal increase in the thoracic curvature, as a result the vertebral column curves posteriorly.
Lordosis
anterior tilting of the pelvis with increased extension of the lumbar vertebrae, producing an abnormal increase in the lumbar kyphosis.
Scoliosis
common in young adults. Is characterized by an abnormal lateral curvature that is accompanied by rotation of the vertebrae.
Cervical nerves and and bones
7 bones, 8 nerves
Coccygeal bones and nerves
3-5 fused bones, 1 nerve
Thoracic bones and nerves
12 and 12
conous medullar in 8 weeks
spinal cord goes to coccyx
conous medullar in 24 weeks
spinal cord goes to s1-s2
conous medullar in newborn
spinal cord to L3-L4
conous medullar in age 2- adult
spinal cord to L1-L2
Dural Sac
Contain CSF, goes from L1/L2-S2
Can't do lumbar puncture past S2
film terminale
thin strand of pia attaching conus medullaris to coccyx
Internal venus plexus found in
epidural space
Internal and external venus plexus
are valveless, can cause cancer metastasis
Lumbar puncture best at
L4-L5 but can technically do it anywhere
sacral hiatus
used for steroid injection. decreased risk of entering subarachnoid space
Needle going through spine midline
Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Epidural space
Dura mater
Arachnoid mater
Subarachnoid space
Needle going through spine laterally
Interspinous ligament
Ligamentum flavum
Epidural space
Dura mater
Arachnoid mater
Subarachnoid space
conus medullaris
end of spinal cord
cauda equina
Spinal nerve roots descending to exit as lumbar and sacral nerves
lateral horn
(only in thoracic and lumbar regions)
- sympathetic motor neurons
C1-C7 spinal nerves
exit above same number vertebrae
C8 spinal nerve
exit above T1 vertebrae
T1- end spinal nerves
exit below same number vertebrae
dorsal ramus
innervates skeletal muscles of the neck and back
ventral ramus
innervates skeletal muscles of everywhere besides the back
disc herniation
Annulus fibrosis cracks and nucleus propusous goes posterior/lateral to the postural longitudinal ligament
Lumbar spinal compression
nerve compressed between L3-L4= L4
nerve that exits between L3-L4= L3
Sensation loss in dermatome
2 or more spinal nerves
Myotome
region of skeletal muscle intreated by a single nerve or spinal cord. Most muscles are innervated by more than 1 spinal cord level
Grey rami vs White rami
Grey= unmyelinated White=myelinated
Sympathetic route
Lateral horn
Ventral Root
Spinal nerve/Ventral Rami
White Rami
Sympathetic chain
Then options:
-Ascend (target go above T1)
-Descend (target below L2)
-Synapse (target between T1-L2)
-Pass through and synapse at pre-aortic ganglia or continue as splanchnic nerve
Parasympathetic route of S2-S4
Later horn
Ventral root
Spinal nerve/Ventral rami
leave as pelvic splanchnic nerves and enter pelvis plexus
post gangly is on wall of target organ
Visceral afferent (sensory) nerves
cell bodies are in dorsal root ganglia
unconscious sensation- travel with parasympathetic
conscious sensations (pain)- travel with sympathetic
blastomeres
Smaller cells produced by cleavage during mitotic cell division
Morula
16-32 blastomeres, develops around day 4
Fluid enters blastocystic cavity of mural creating
embryoblast at embryonic plate (inner cell mass)
trophoblast= the fetal components of the placenta (peripheral cell mass)
Around day 6 Trophoblast divides into
cytotrophoblast and syncytiotrophoblast
Cytotrophoblast
makes cells= mitotically active, divided from trophoblast
Syncytiotrophoblast
secrete hCG and erodes endometrial connective tissue enabling the blastocyte to burrow into the endometrium
ectopic pregnancy
implantation of the fertilized egg in uterine tube which could lead to rupture/hemorrhage
decreased hCG level
2 layers develop at embryonic disc
Epiblast= form floor of amniotic cavity and are composed of a thick layer of high columnar cells
Hypoblast= form roof of exocoelomic cavity and are composed of small cuboidal cells
Embryonic disc lie between
primary umbilical vesicle (hypoblast and exocoleomic membrane line this) and amniotic cavity (epiblast)
primitive streak
caudal elevation that occurs first during gastrulation
primitive node
cephalic end of primitive streak
primitive pit
Depression in primitive node that eventually tunnels to get the notochord
Sacrococcygeal teratoma
common tumor in female newborns. caused by remnants of pluripotent primitive streak in caudal region of embryo
Adult remnants of notochord
nucleus proposus and apical ligament
Paraxial mesoderm forms
somites (3 derivatives)
-dermatome (dermis/fibroblasts)
-scleratome (vertebrae/ribs)
-myotome (primordial muscle cells)
Around day 22
neural folds begin to fuse closing neural grove (notochord ventral) at occipital and cervical regions
closer causes neural crest cells to get squeezed out
Neuropore closure
Rostral neuropore of neural tube closes first around day 25
Caudal neuropore of neural tube closes second around day 27
Alpha Fetal Protein (AFP)
elevated levels in amniotic fluid and maternal blood are associated with neuropore failure to close properly
ectoderm forms
skin and covers neural tube
Marginal zone
early ouster part of spinal cord that eventually forms white matter
ventricular zone
thick layer of neuroepithelium that lines neural tube and forms ependymal layer (forms CSF. Also migrates to form intermediate zone
Intermediate zone
Differentiate into neuroblasts which form neurons
thickens to 4 regions which form grey matter
-Alar plates (dorsal horns)
-Basal plates (Ventral somatic motor and lateral horns)
sulcus limitans
separates alar and basal plates
Neural crest derivatives
MOTEL PASS- melanocytes, odontoblasts, tracheal cartilage, enterochromaffin cells, leptominigies, psuedounipolar cells, all ganglionic cells and adrenal medulla, schwas cells, spiral membrane
Chordoma
a rare, bone tumor arising from primitive notochord cells; usually occurs at the base of the spine (sacrum) or at the skull base (clivus).
Why take folic acid?
neurolation happens during the 1st month (before even know pregnant)
spina bifida occulta
most common and least severe form of spina bifida without protrusion of the spinal cord or meninges
tuft of hair common and no neuro deficits
spina bifida cystica with meningocele
external protruding sac contains meninges and CSF
spina bifida with myelomeningocele
protrusion of a sac through the spine, containing cerebral spinal fluid and meninges as well as the spinal cord or nerve roots.
Severe neurological defects
Spina bifida with myeloschisis
Most severe form, with no overlying meninges, baby more prone the life threatening infections, caudal neuropore does not close at end of Week 4
crush fracture
crushing of vertebral body
landmarks for L4-L5 lumbar puncture
highest points of illiiic crest
internal vertebral plexus
surrounds the dura mater in the epidural space
denticulate ligament torn
lateral shift in spinal cord to the left
lumbar cistern
subarachnoid space inferior to medullary cone that contains cauda equina and CSF
whiplash injury
anterior longitudinal ligament injury
Complete tear at right alar ligament results in
increased rotation
denticulate ligament
Used as a landmark to identify anterior rootlets from posterior rootlets
Intramembranous bone formation (flat bones)
-mesenchymal cells to osteoprogenitor cells to osteoblasts to osteocytes
-develop periosteum
-osteoblast recreate osteoid (bone matrix) to form irregularly shaped bone spicules (create spongy bone)
-spicules enlarge by appositional growth and join into trabecular network
-blood vessel maneuver into bone
-periosteum formed in the edges
-woven to compact bone (spongey bone still in middle)
endochondral bone formation (more common)
create bone collar
has appositional and intersistial growth (length- uses epiphyseal plate)
has articular cartilage
bone tissue replaces a cartilage model of a bone
-primary and secondary ossification
zone of reserve cartilage
resting zone (1)
zone of proliferation
chondrocytes multiply forming isogenous groups (2)
zone of hypertrophy
contains greatly enlarged cells that are metabolically active (3)
zone of calcified cartilage
matrix becomes calcified, hypertrophied cells being to die (4)
zone of resorption
Eroded cartilage nearest the diaphysis (5)
Lack of Calcium, bone results
poorly calcified bone
-leads to Rickets and Osteomalacia
Vitamin A deficiency vs excess
Inhibits proper bone formation and growth
While excess accelerates the ossification of the epiphyseal plates and makes bone fragile
PTH indirectly stimulates
osteoclasts to resorb and release calcium thus increasing blood calcium levels
Calcitonin
Lowers blood calcium levels by inhibiting matrix resorption and prevent calcium release
type 1 osteoporosis
postmenopausal= estrogen decrease
estrogen limits osteoclast activity normally
type 2 osteoporosis
elderly- develop as consequence of drug therapy (corticosteroids) or disease (malnutrition, cancer)
bone repair steps
1. Hemorrhaging is followed by blood clotting
2. macrophages remove debris via phagocytosis
3. Fibroblasts proliferate in the periosteum and endosteum
4. Chondrocytes also differentiate
5. A fibrocartilaginous callus is formed both internally and externally→soft callus
6. osteoblasts differentiate from the periosteum and endosteum and lay down bony matrix on the outer surface of the callous ( intramembranous ossification)
7. Cartilage is replaced by bone via endochondral bone formation This forms a hard callus of primary (immature) bone.
8. Bony callus is eventually resorbed and replaced with secondary bone as the repair process continues
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