Histology Exam 1 Flashcards
what are the functions of cartilage?
provide flexible support
articular surfaces of joints
temporary template for skeleton
spaces chondrocytes sit in
lacunae
what are the ECM components of cartilage?
type 2 collagen
hyaluronic acid
GAGs
dense outer layer of cartilage- what are its two layers
perichondrium- outer fibrous layer and inner cell layer with progenitor cells
what is interstitial growth?
growth from within- chondrocytes make matrix around themselves and then get trapped
group of chondrocytes in a lacunae
isogenous group
what is appositional growth?
growth on a surface- progenitor cells in perichondrium differentiate into chondroblasts and make new matrix
how does cartilage develop?
interstitial growth to begin, then appositional is used for repair
where is hyaline cartilage?
upper airway (trachea, bronchii, larynx)
joints
ventral ribs
early skeleton
what is hyaline cartilage made of?
type 2 collagen
where is elastic cartilage?
epiglottis
larynx
ear
eustachian tube
what is elastic cartilage made of
type 2 collagen
elastin fibers
where is fibrocartilage
IVD
pubic symphysis
what is fibrocartilage made of
type 1 and 2 collagen
where does cartilage get nutrients from?
surrounding connective tissue
bone matrix
collage type 1
GAGs
proteoglycans
non collagenous proteins
where do osteoblasts come from?
osteoprogenitor cells
where do osteoclasts come from?
blood cell precursor, monocyte lineage
where do osteocytes come from?
osteoblasts that get stuck in the matrix
what type of marrow is active?
red
what type of marrow is inactive?
yellow
what layer of bone has progenitor cells in it? where is it?
endosteum- between compact and spongy bone
what is the layer on the outside of bone?
periosteum
where are osteoblasts found? what do they look like?
cells in a line on the surface- do appositional growth
what are the phases of osteocytes?
quiescent- resting
formative- signal bone deposition
resorptive- signal bone resorption
which type of bone cells is multinucleated?
osteoclasts
what are hawship canals?
holes osteoclasts sit in
how are osteoclasts made?
osteoblasts produce MCSF which recruits monocyte stem cells to bone and RANKL
osteoclast precursor cells have RANK, RANKL binds to RANK and induces differntiation
what is osteoprotegrin?
blocks RANK and inhibits osteoclast maturation
steps of bone resorption
- osteoclasts target bone via chemotaxis
- attach via cell adhering molecules
- seal to bone forming a resorptive cavity
- release H to dissolve minerals (acidic environment)
- lysosomes degrade collagen, MMPs degrade other things
what are lamellae?
concentric layers of bone surrounding Haversian cannals
steps of bone formation
osteiod is deposited (unmineralized bone)
osteoblasts release stuff that attracts Ca and PO4-
hydroxyapetite crystals form
continuous remodeling
what does osteoid look like
very irregularly arranged collagen
what happens to the osteoid?
reabsorbed by osteoclasts
what are the 2 types of bone formation?
intramembranous
endochondral
describe intramembranous bone formation
osteoblasts secrete matrix which is then mineralized
the bone is resorbed and reshaped
what is intramembranous bone formation used for?
flat bones
describe endochondral bone formation
cartilage forms first and then is replaced by bone
what is endochondral bone formation used for
long bones
steps in endochondral bone formation
- temporary hyaline cartilage skeleton formed which is surrounded by perichondrium
- bone formation starts in specific areas and moves outwards
where is the primary ossification center?
in the middle of the diaphysis
where is the secondary ossification center
epiphyses
what does parathyroid hormone related peptide do?
stimulates chondrocyte proliferation in the temporary cartilaginous skeleton
what causes dwarfism?
defects in Indian hedgehog protein- chondrocytes don’t proliferate enough so bones aren’t long eough
what does indian hedgehog protein do?
increases PHrP receptors on chondrocytes to delay hypertrophy until the bone gets to be the correct length
what does fibroblast growth factor do?
inhibits cartilage growth
what causes achondroplastic dwarfism?
gain of function mutation in FGF- increased FGF binding inhibits cartilage growth, so bones aren’t correct length
what regulates periosteal collar formation?
indian hedgehog protein
what is rickets?
vitamin D defiency in children resulting in soft bones due to defects in mineralization
what is osteomalacia?
vitamin D deficicy in adults resulting in demineralization of bone–>soft bones
what is osteoporosis?
increased bone fragility due to estrogen deficiency–> increased bone resorption without increased formation
what is Paget’s disease
osteoblasts overcompensate for high osteoclast activity by laying down a lot of woven bone resulting in abnormally large bones that are prone to fracture because the osteoid isn’t mineralized
synarthrosis?
immovable joint
amphiarthrosis
slightly movable joint
diarthrosis
movement
osteoarthritis
excessive wear of articular cartilage with secondary inflammation
rheumatoid arthritis
chronic systemic inflammation leading to thickening of synovial membrane
what is a pannus?
folds in synovial membrane from rheumatoid arthritis
what is bone fusion?
ankylosis
what is gout?
crystals deposits in joints
where is skeletal muscle?
typical muscles
extraocular muscles of eye
where is visceral striated muscle?
in soft tissue- tongue, pharynx, lumbar diaphragm, upper esophagus
where is cardiac muscle?
heart
large veins that drain into heart
why is connective tissue required for force transduction
ends attach muscles to other organ systems
forms tendon attachment
nerves and blood vessels are in it
type 1 fibers
slow oxidative most metabolically active high mitochondria high myoglobin and cytochrome c fatigue resistant small red
type 2a fibers
fast oxidative glycolytic middle size and color high myoglobin and glycogen anaerobic glycolysis fatigue resistant generate peak tension
type 2b fibers
fast glycolytic large white fibers fatiguable high anaerobic activity highest ATPase activity generate high peak tension used for precise movements high nerve innervation
H band
myosin only- shrinks with contraction
A band
whole myosin filament- stays constant
I band
actin only- shrinks with contraction
what does alpha actinic do
bundles actin and anchors it to z line
what does nebulin do
helps alpha actinic anchor actin to z line
what does tropomodulin do
caps actin filaments for stabilization
what does tropomyosin do
regulates muscle contraction- 3 binding sites
what is titin
anchors myosin to z line
what is myomesin
holds thick filaments in order at m line
what is c protein
holds thick filaments in order at M line
what is the smallest contractile unit
sarcomere- z line to z line
what do muscle spindles do?
provide proprioception information
what innervates muscle spindle fibers?
gamma efferent neurons
where are the nuclei in skeletal muscle fibers?
pushed out of fiber
where are the nuclei in cardiac muscle fibers?
in center of fiber
what makes cardiac muscle look different from skeletal muscle?
nuclei are in center of fibers
intercalated discs
fibers branch
what type of muscle has terminal cisternae
skeletal muscle
what are purkinje fibers
specialized cardiac muscle cell that propagates signal through ventricles
what do purkinje fibers look like?
large nuclei that don’t stain well
lots of glycogen
intercalated discs
what are the things in an intercalated disc?
desmosome
adherent junctions
gap junctions
what regulates smooth muscle contraction?
ca and calmodulin and MLCK
what are dense bodies?
attach thin and intermediate filaments to the membrane, connected by alpha actinin
3 layers of skin
epidermis
dermis
hypodermis
what is the tissue that makes up the epidermis?
keratinized stratified squamous epithelium
what cells are in the epidermis?
keratinocytes
layers of the epidermis superficial to deep
stratum corneum stratum lucidum stratum granulosum stratum spinosum stratum basale
describe stratum basale
attached to basal lamina via hemidesmosomes
cells attached to each other via desmosomes
highest proliferation rate
describe stratum spinosum
spiny cells with processes filled with keratin
moderate cell proliferation
processes connected by desmosomes
describe stratum granulosum
thin layer with keratinosomes (lamellar bodies) that release phospholipids to coat keratinocytes to make them waterproof
stratum lucidum
cells lose organelles as they move up and die
plasma membrane is packed with keratin
**only in thick skin
stratum corneum
keratinocytes filled with keratin filaments cross link with other proteins
layer in which shedding occurs- rates vary by location
what is unique about thick skin?
thick stratum corneosum
hairless
where is thick skin?
palms and soles
what is unique about thin skin?
has hair
thin stratum corneosum
what are finger and toe prints?
epidermal ridges
where is hard keratin?
hair
where is soft keratin?
skin
what are other cells in the epidermis?
melanocytes
langerhan cells
merkel cells
what are melanocytes derived from?
neural crest
what do melanocytes do?
make melanin
what determines pigmentation?
rate of melanin synthesis, transfer, and degradation
what are the 3 types of melanin?
eumelanin- black or brown
pheomelanin- red
neuromelanin- brain
what causes gray hair?
decreased melanin synthesis and increased H2O2 due to decreased catalase
what is the science word for moles?
navi
what is tyrosine kinase used for in skin?
melanin synthesis
albanism
defect in melanin synthesis
vitiligo
decreased number of melanocytes per area
melanoma
neoplastic transformation of melanocytes
purpose of langerhan cells
immune- antigen presenting
purpose of merkel cells
specialized cell receptor that synapses with sensory neurons for touch
what are the layers of the dermis?
papillary layer (top) reticular layer (bottom)
what is in the papillary layer?
loose CT
blood vessels
receptor endings
type 7 collagen and fibrillian
what is in the reticular layer?
dense irregular CT
elastic fibers
reticular fibers, type 1 collagen
what is in the hypodermic?
loose connective tissue
adipose
what is the nail equivalent to?
stratum corneum
what is the nail bed equivalent to?
stratum basale and spinosum
what layer are hair follicles from?
epidermis
parts of a hair follicle
hair bulb dermal papilla hair shaft inner root external root hair cuticle
what is the hair bulb?
produces the hair shaft and internal root sheath
what is the dermal papilla
bulb base from CT
how do sebaceous glands secrete
holocrine secretion onto hair follicles or epidermis surface
what are the types of sweat glands
merocrine
apocrine
modified apocrine
describe merocrine sweat glands
secrete a watery/salty solution liver most of body, used for thermoregulation
describe apocrine sweat glands
viscous secretion triggered by external stimulus
located in perineum, anus, and axilla
where are modified apocrine sweat glands?
external ear
eyelids
where are arrestor pilli muscles?
smooth muscle bundles between the epidermis and the hair bulb
what are free nerve endings for
thermal
pain
light tough
what are merle discs for
touch
what are meissner’s corpuscles for, where are they, what do they look like
touch
in the papillary dermis
round
what are pacinian corpuscles for, where are they, what do they look like?
pressure
hypodermis
encapsulated- onion like
what are rufini organs for and where are they
stretch
dermis
what is hyperkeratosis
thickening of corneum and granulosum
what is parakeratosis
corneum cells keep their nuclei–normal in oral cavity but also associated with pathological conditions
what is acanthosis
abnormal epidermal thickening (spinosum)
long epidermal extensions into papillary layer of dermis
associated with chronic inflammatory conditions
“sugar line”
what is intraepidural edema
fluid accumulation in epidermis
associated with trauma
eczema
inflammatory, allergic component
psoriasis
chronic inflammatory disease characterized by rapid keratinocyte proliferation with fast upward movement resulting in surface cells not having enough keratin
scaly white regions an dmicroabcesses in dermis
basal cell carcinoma
invades dermis, but rarely metastasizes
neoplastic transformation of stratum basale
squamous cell carcinoma
well demarcated highly keratinized tumors that invade the dermis and regional lump nodes