muscles and bones biology

Question 1

muscle contraction - steps

Answer 1

neurotransmitter release –> postsynaptic ligand –> depolarization –> Ca2+ release from sarcoplasmatic reticulum –> troponinin C to tropomyosin system –> displacement of myosin on the actin filament –> myosin binds and hydrolyses ATP

Question 2

muscle contraction - neurotransmitter release is caused by

Answer 2

action potential depolarization opens presynaptic voltage-gated Ca2+ channels, inducing neurotransmitter release

Question 3

muscle contraction - postsynaptic ligand leads to

Answer 3

muscle cell depolarization in the motor end plate

Question 4

muscle contraction - depolarization process

Answer 4

it starts from ligand binding –> depolariztion travels along muscle cell and down the T - tubule

Question 5

muscle contraction - depolarization result to –>

Answer 5

depolarization of the voltage-sensitive dihydropyridine receptor, mechanically coupled to the ryanodine receptor on the sarcoplasmic reticulum –> conformation change
–> Ca2+ release from sarcoplasmic reticulum

Question 6

muscle contraction - Ca2+ action (and mechanicals changes)

Answer 6

released Ca2+ binds to troponin C causing a conformation change that moves tropomyosine out of the myosin-binding groove on actin filaments

Question 7

muscle contraction - myosin action

Answer 7

myosin release bound ADP and inorganic PO4(3-) –> displacement of myosin on the actin filament (power stoke) –> binding a new ATP causes detachment of myosin head from actin filament –> hydrolysis –> high energy position (cocked) for the next cycle

Question 8

sarcomere anatomy - M line

Answer 8

M line: middle line

Question 9

sarcomere anatomy - H band

Answer 9

myosin between myosin heads (in the middle of the sarcomere)

Question 10

sarcomere anatomy - A band

Answer 10

all myosins (in the same sarcomere) (thick filaments)

Question 11

sarcomere anatomy - I band

Answer 11

from the end of the myosins of the one sarcomere to the end of the myosins of the next sarcomere

Question 12

sarcomere anatomy - Z lines

Answer 12

the lines of sarcomere

Question 13

transverse (T) tubules?

Answer 13

extensions of plasma membrane part of juxtaposed with terminal cisternae (part of sarcoplasmic reticulum)

Question 14

Terminal cisternae are

Answer 14

enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules

Question 15

T tubules and Terminal cisternae - numbers

Answer 15

in skeletal muscle: 1 T + 2 terminal cisternae (triad)

in cardiac muscle: 1 T + 1 terminal cisternae (diad)

Question 16

contraction - appearance of bands

Answer 16

• shortening of H band + I band + sarcomere

- A band remains the same length

Question 17

H band after contraction

Answer 17

shorter

Question 18

A band after contraction

Answer 18

same

Question 19

I band after contraction

Answer 19

shorter

Question 20

sarcomere band after contraction

Answer 20

shorter

Question 21

muscle contraction - postsynaptic ligand binding leads to muscle cell depolarization in the

Answer 21

motor end plate

Question 22

muscle depolarization travels muscle cell and down the

Answer 22

T-tubule

Question 23

muscle cells - T-tubule receptor

Answer 23

dihydropyridine receptor

Question 24

muscle cells - sarcoplasmic reticulum receptor

Answer 24

ryanodine receptor

Question 25

Types of muscle fibers

Answer 25

1. type 1 muscle | 2. type 2 muscle

Question 26

sarcomere - thick filaments

Answer 26

myosin

Question 27

sarcomere -thin filaments

Answer 27

actin

Question 28

types 1 vs type 2 - functional characteristic

Answer 28

type 1 - slow twitch | type 2 - fast twitch

Question 29

types 1 vs type 2 - colour (why)

Answer 29

type 1 - red (increased mit and myoglobin) | type 2 - white (decreased mit and myoglobin)

Question 30

types 1 vs type 2 - metabolism (why)

Answer 30

type 1 - oxidative phosph (increased mit and myoglobin) | type 2 - anaerobic glyc (increased mit and myoglobin)

Question 31

muscle fibers with sustained contraction

Answer 31

type 1

Question 32

muscle fibers - weigh training results in

Answer 32

hypertrophy of fast-twitch (2) muscle fibers

Question 33

fast twitch muscle fibers - type?

Answer 33

2

Question 34

slow twitch muscle fibers - type?

Answer 34

1

Question 35

Osteoblasts action

Answer 35

build bone by secreting collagen and catalyzing mineralization

Question 36

bone mineralization is process in which

Answer 36

crystals of calcium phosphate are produced and laid down within the bone’s fibrous matrix

Question 37

Osteoblasts - differentiate from

Answer 37

mesenchymal stem cells

Question 38

Osteoblasts - differentiate from (where)

Answer 38

mesenchymal stem cells | in periosteum

Question 39

osteoclasts appearance

Answer 39

multinucleated cells

Question 40

osteoclasts action

Answer 40

dissolve bone by secreting acid and collagenases

Question 41

osteoclasts - differentiate from

Answer 41

monocytes | macrophages

Question 42

parathyroid hormone action on bone

Answer 42

- low, intermittent levels --> anabolic effects (building bone) on osteoblasts and osteoclasts (indirect) - chronically increased PTH (1ry hyperparath) --> catbolic effect (osteitis fibrosa cystica

Question 43

estrogen action on bone

Answer 43

1. inhibits apoptosis in osteoblasts | 2. induce apoptosis in osteoclasts

Question 44

bone - estrogen deficiency -->

Answer 44

excess cycles of remodeling --> bone resorption leads to osteoporosis

Question 45

bone - multinucleated cells

Answer 45

osteoclasts

Question 46

bone - monocytes and macrophages are differentiate to

Answer 46

osteoclasts

Question 47

bone - mesenchymal stem cells are differentiate to

Answer 47

osteoblasts

Question 48

bone formation - types

Answer 48

1. endochondral ossification | 2. Membranous ossification

Question 49

bone formation - membranous ossification - which bones

Answer 49

bones of calvarium and facial bones

Question 50

bone formation - endochondral ossification - which bones

Answer 50

bones of axial and appendicular skeleton and base of the skull

Question 51

bone formation - membranous ossification - mechanism

Answer 51

woven bone formed directly without cartilage. Later remodeled to lamellar bone

Question 52

bone formation - endochondral ossification - mechanism

Answer 52

Cartilaginous model of bone is first made by chondrocytes. Osteoclasts and osteoblast later replace with woven bone and then remodel to lamellar bone

Question 53

woven bone is also called

Answer 53

fibrous bone

Question 54

in adults woven bone occurs after

Answer 54

fractures and in Paget disease

Question 55

smooth muscle contraction process

Answer 55

membrane depolarization --> L-type voltage gated Ca2+ channe --> increased intracellular Ca2+ --> increased Ca2+-calmodoulin complex --> activation of MLCK --> Myosin - p (+ actin) --> contraction (via cross bridging)

Question 56

MLCK

Answer 56

myosin-light-chain- kinase

Question 57

MLCK (myosin-light-chain- kinase) action

Answer 57

myosin+actin --> myosin-P+actin

Question 58

Smooth muscle cell - vasodilator

Answer 58

Nitric oxide (NO)

Question 59

Ca2+ vs NO on smooth muscle contraction

Answer 59

Ca2+ --> contraction | NO --> relaxation

Question 60

NO associated relaxation of smooth muscles - process

Answer 60

NO --> activation of Guanylate cyclase --> increased cGMP (from GTP) --> activation of MLCP --> Myosin+actin (no Pi) --> relaxation

Question 61

MLCP

Answer 61

myosin-light-chain-phosphatase

Question 62

MLCP (myosin-light-chain-phosphatase) action

Answer 62

Myosin-P+actin --> Myosin+actin

Question 63

MLCP vs MLCK according action and results

Answer 63

MLCP --> Myosin-P+actin --> Myosin+actin --> relaxation | MLCP --> myosin+actin --> myosin-P+actin --> contraction

Question 64

NO synthase - action

Answer 64

L-arginine --> NO