ANSC 230 Exam 3

what is cartilage?

a type of supporting connective tissue

what is the function of hyaline cartilage?

lines the ends of bones at joints

what are chondrocytes?

cells of cartilage

what is the function of chondrocytes?

secrete extracellular matrix surrounding the lacunae where they live

what are the two kinds of ossification?

endochondral and intramembranous

what are the two processes that form bone during fetal development of the mammalian skeleton?

endochondral ossification and intramembranous ossification

what does endochondral ossification involve?

replacement of hyaline cartilage by bone

what is the epiphyseal growth plate?

a residual plate of hyaline cartilage on the ends of a long bone

what is the site of longitudinal bone growth during post-natal development?

epiphyseal growth plate

how long does longitudinal bone growth continue?

until early adulthood

what is longitudinal bone growth mediated by?

growth hormone and IGF-1

what does an increase in growth hormone trigger?

an increase in IGF-1

where does IGF-1 come from?

liver

what does IGF-1 trigger?

growth

where does growth hormone come from?

anterior pituitary gland

what leads to the formation of the epiphyseal line?

hyaline cartilage of the growth plate being replaced by bone after puberty

what is the replacement of the cartilage growth plate by bone mediated by?

estrogen during puberty

what are the four zones in a long bone?

reserve cartilage, proliferation, hypertrophy, and calcification

what does the zone of reserve cartilage contain?

small chondrocytes embedded in a hylaine cartilage matrix

which zone is located closest to the epiphysis?

reserve cartilage

what does the zone of proliferation contain?

larger proliferative chondrocytes arranged in columns undergoing mitosis

which zone pushes the epiphysis away from th diaphysis, elongating the bone shaft?

proliferation

where is the zone of proliferation located?

in between reserve cartilage and hypertrophy

what happens in the zone of hypertrophy?

chondrocytes grow larger, creating wider lacunae that form tunnels through the bone

where is the zone of hypertrophy located?

in between proliferation and calcification

what happens to chondrocytes in the zone of calcification?

they become embedded in a calcified extracellular matrix and die

what happens to osteoblasts in the zone of calcification?

they invade and secrete bone tissue onto the walls of the calcified cartilage matrix tunnels

how are concentric lamellae of new osteons formed?

osteoblasts become trapped in the bone matrix and differentiate to become osteocytes

what kind of bone growth can happen in adulthood?

appositional

what key thing is missing in appositional bone growth compared to longitudinal?

cartilage

what is the more major type of bone growth?

longitudinal

what is appositional bone growth?

increase in bone width instead of length

in which type of bone growth does the medullary cavity diameter increase?

appositional

what is the bone remodeling process in appositional bone growth?

new layers of compact bone are added to the outside of the shaft while old bone is removed from the inside

what is appositional bone growth controlled by?

osteogenic progenitor cells

what are osteogenic progenitor cells?

dormant cells within the inner cellular layer of the periosteum

what can osteogenic progenitor cells differentiate into?

osteoblasts

what is an example of appositional bone growth?

play tennis with right hand, so right arm bone is denser

what are the stem cells in the deep layer of the periosteum?

osteogenic progenitor cells

what do osteogenic progenitor cells proliferate in response to?

a growth stimulus

what do osteoblasts do?

form new bone tissue

what are osteocytes formed from?

osteoblasts trapped in the bone they produce

what do osteocytes do?

form circumferential lamellae of compact bone

what do osteoclasts do?

resorb bone from the endosteum

what does the function os osteoclasts result in?

layer of compact bone being pushed outward and marrow cavity expands in diameter

what is the process that is a hybrid of longitudinal and appositional bone growth?

bone repair

how long is the reaction phase of bone repair?

hours

how long is the repair phase of bone repair?

days

how long is the remodeling phase of bone repair?

weeks to years

what happens in the reaction phase of bone repair?

blood cells accumulate at the site of injury, and a clot forms as a hematoma

what are the functions of the hematoma/clot formed in bone repair reaction phase?

stop blood loss and act as a base for callus formation

what happens in the repair phase of bone repair?

osteogenic progenitor cells form chondrocytes, which make a hyaline cartilage callus, which is converted vua endochondral ossification into a spongy bone callus

what happens in the remodeling phase of bone repair?

spongy bone callus is gradually replaced with compact bone, trabeculae are resorbed, and mineralized bone matrix is formed

what are the three hormones that control calcium balance?

calcitriol, parathyroid hormone, and calcitonin

which hormone is the active form of vitamin D?

calcitriol

what is the result of calcitriol release?

increased intestinal Ca2+ absorption, thus increased blood Ca2+ levels

what does PTH release do?

stimulates osteoclasts to resorb bone and stimulates calcitriol production

what is the result of PTH release?

increased blood Ca+ from osteoclasts and reduced Ca2+ loss in urine

what is calcitonin secreted by?

parafollicular cells of the thyroid

what does calcitonin release do?

inhibits osteoclast bone resorption and acts on the kidneys

what is the result of calcitonin release?

decreased blood Ca+ from inhibited osteoclasts and increased Ca2+ loss in urine

what is the most prevalent type of muscle tissue?

skeletal

what percent of body weight does muscle tissue make up?

50%

what is contractility for muscles?

muscle cells undergo contraction, where they change their shape to become shorter

what is excitability in muscles?

muscle cells can receive and respond to electrical signals in the form of action potentials/nerve impulses

what is extensibility/elasticity in muscles?

muscle tissue can stretch beyond its resting length and return to its original shape without tissue damage

what are the three types of muscle tissue?

skeletal, cardiac, and smooth

which two types of muscle tissue are striated?

skeletal and cardiac

which type of muscle tissue has muscle fibers with many peripherally located nuclei?

skeletal

what are muscle fibers/myofibers?

long cylindrical skeletal muscle cells

what are the roles of skeletal muscle?

voluntary body movement, posture, breathing, generated body heat(shivering)

which type of muscle is the major tissue component of meat?

skeletal

which type of muscle tissue has short branched cells with a single central nucleus?

cardiac

what is the role of cardiac muscle?

autonomic control of heart contraction to pump blood to the circulatory system

which type of muscle tissue has short spindle shaped cells with a single central nucleus?

smooth

what are the roles of smooth muscle?

autonomic control of digestion, constriction/dilation of blood vessels, respiratory and reproductive tracts

which way to striations face?

perpendicular to muscle/myo fibers

what is the myotendinous unit?

where skeletal muscle inserts into bone via a tendon

what are tendons made of?

dense regular connective tissue

what is the connective tissue layer surrounding each individual muscle called?

epimysium

what is the connective tissue layer around a bundle of muscle cells/myofibers or fascicle called?

perimysium

what is the connective tissue layer surrounding each individual muscle cell/myofiber called?

endomysium

what is a fascicle?

a bundle of muscle cells/myofibers

what is the specialized organelle of striated muscle that enable contraction?

myofibril

can a muscle cell contain multiple myofibrils?

yes, they all do

how are myofibrils arranged?

parallel to each other

what is the individual contractile unit of a myofibril?

sarcomere

can a myofibril have multiple sarcomeres?

yes, they all do

how are sarcomeres arranged?

in series

what is the measurement of one sarcomere?

z-line to z-line

what are the thin filaments?

actin, tropomyosin, and troponin

what are the thick filaments?

myosin and myosin head

what is the structural component of the I band?

actin

what is the contractile unit of the thin filament?

actin

which thin filament covers the active site on actin to prevent interaction with myosin?

tropomyosin

what thin filament binds to tropomyosin and has binding sites for Ca2+?

troponin

what is the structural component of the H zone?

myosin

what overlaps with actin at the A band?

myosin

what binds to actin when it’s not covered by tropomyosin?

myosin head

what is the sarcoplasmic reticulum?

the endoplasmic reticulum of muscle cells