histo Flashcards
cytoplasm
sarcoplasm
smooth er
sarcoplasmic reticulum
muscle cell membrane and it’s external lamina
sarcolema
dense irregular connective tissue; surrounds the muscle fiber
endomysium
thin connective tissue; surrounds each fascicle
perimysium
connects muscle to the bone, skin, or another muscle
myotendinous junction
reserve progenitor cells, fuses together following injury or trauma
satellite cell
•slow contractions for a long period of time without fatigue
•fibers: dark or red
slow oxidative muscle fibers
•rapid, short term contractions, leading to rapid fatigue
•fibers: white
•anaerobic metabolism of glycogen to glucose produces lactic acid
• accumulation of lactic acid leads to rapid fatigue
fast glycolytic fibers
intermediate between the two types
fast oxidative-glycolytic fibers
long cylindrical filament bundles in the sarcoplasm
myofibrils
anistropic, birefringent in polarized microscope
A band (dArk band)
isotropic, does not alter polarized light
I band (lIght band)
transverse line bisecting the I band
Z disc
repetitive contractile subunit
sarcomere
due to the arrangement of myofilaments: myosin and f actin
band pattern
thick filament
myosin
thin filament
actin
synthesize proteins to make myofilaments
myotubes
coil of two polypeptide chains in the groove between two twisted actin strands
tropomyosin
complex with three subunits
troponin
attaches to tropomyosin
TnT (troponin T)
binds calcium
TnC (troponin C)
regulates actin myosin interaction
TnI (troponin I)
acting-binding protein thay anchors actin filaments perpendicularly om the Z disc
a-actinin
largest protein in the body supporting the thick myofilaments and connects them to the Z disc
Titin
binds each thin myofilament leterally, helps anchor them to a-actinin, and spececies lenght of the actin polymers
nebulin
lighter zone central of A band
H zone
bisects H zone
M line
myomisin-binding protein in M line that holds thick filaments in place
myomesin
enzyme that catalyzes transfer of phosphate groups from phosphocreatine to ADP
creatine kinase
has pumps and proteins for calcium sequestration that is released in sarcolemma
sarcoplasmic reticulum
triad triggering calcium release when sarcolemma is depolarized
transvers or t-tubule
•mutations of dysthropin gene: involved in functional organization of myofibrils
•lead to defective linkages between cytoskeleton and ECM
•resulting to atrophy of muscle fibers
Duchenne muscular dystrophy
increased cell size
hypertrophy
increased number of cells
hyperplasia
decreased cell size
atrophy
•”visceral muscle”
•major component of blood vessels, digestive, respiratory, urinary,and reproductive tracts and its organ
smooth muscle tissue
network of type l and lll collagen fibers
endomysium
plasmalemma invagination containg the major ion channels controlling the calcium release
caveolae
release of calcium from sarcoplasmic cisternae at myofibrils
initiate contraction
myofibrillar arrays of actin and myosin arrange in a criss cross pattern
generate contraction
autonomic nerves
stimulate contractions
•calmodulin
•myosin light-chain kinase (mlck)
proteins producing contraction
benign tumos but seldom problematic
leiomyomas
occuring in the wall of the uterus and produce painful pressure and unexpected bleeding as it grows larger
fibroids
•mature cardiac muscle cell: 15-30 um wide, 85-120 um long with one central nucleus
cardiac muscle tissue
rich capillary network
endomysium
thick, forming large masses of fibrous connective tissue, resulting to the “cardiac skeleton”
perimysium
transverse lines that represent interfaces adjacent cells and junctional complexes (veins, arteries, and nerves)
intercalated discs
composed of many desmosomes
cardiac muscle tissue
provide the ionic continuity between the cells, serving as “electrical synapses”
gap junctiona
well-developed with large lumens and penetrate the sarcoplasm
t-tubules in ventricular muscle fibers
profiles in junctions between its terminal cisterns and t-tubules
dyad
tissue damage due to the lack of oxygen when coronary arteries are occluded by heart disease
ischemia
tough, durable form of supporting connective tissue
cartilage
•receives nutrients by diffusion from perichondrium
• Lacks nerves and has low metabolic rate
Avascular
glycosaminoglycans and proteoglycans interacting with collagen and elastic fibers
ECM
• Interaction between type II collagen
fibrils and proteoglycans linked to hyaluronan
Matrix
• cartilage cells
• Synthesize and maintain ECM components: type II collagen and other ECM components
• Location: lacunae
chondrocytes
• Most common
• Homogenous and semi transparent
• Covered by perichondrium: essential for
growth and maintenance
• Outer: type I collagen fibers and
fibroblasts
• Inner: mesenchymal stem cells
Hyaline cartilage
• articular surfaces of movable joints, walls of larger respiratory passages, ventral ends of ribs, epiphyseal plates of long bones
• Embryo: forms temporary skeleton
Adults
major regulator of hyaline cartilage growth
somatotropin
• Abundant network of elastic fibers and meshwork of type II collagen fibrils
• Resulting to yellowish color
elastic cartilage
location of elastic cartilage
auricle of the ear, walls of external auditory canals, auditory (Eustachian) tubes, epiglottis, and upper respiratory tract
Mingling of hyaline cartilage and dense connective tissue
fibrocartilage
location of fibrocartilage
intervertebral discs, attachments of certain ligaments, pubic symphysis
• embryonic cartilage formation
• Mesenchymalcells–chondroblasts– chondrocytes
• Superficial mesenchyme: develops as perichondrium
chondrogenesis
mitotic division of preexisting chondrocytes
interstitial growth
chondroblast differentiation from progenitor cells in perichondrium
appositional growth
• Mutations in FBN1 gene: encodes for fibrillin-1
• Essential in formation of elastic fibers within connective tissue
• Abnormalities: skeletal, cardiovascular, ocular, pulmonary, dural ectasia, etc.
Marfan syndrome
• Gradual loss or physical change of hyaline cartilage lining the articular ends of bones in joints
osteoarthritis
Due to increased uric acid crystals
gouty arthritis
