muscular and skeletal systems

Question 1

Which muscle types are striated

Answer 1

skeletal and cardiac

Question 2

tendons

Answer 2

attaches muscle to bone

Question 3

flexing and extending of skeletal muscle

Answer 3

flexing -reducing angle of joint

extending -increasing angle of joint

Question 4

origin and insertion of skeletal muscle

Answer 4

origin - where muscle attaches

insertion - where muscle attaches on the bone more distant from the center of the body

Question 5

fascicles

Answer 5

bundles that allow flexibility within the muscle

Question 6

How many nerves innervate skeletal muscle

Answer 6

skeletal muscle is innervated by a single nerve ending

Question 7

sarcolemma

Answer 7

cell membrane of myofiber

Question 8

actin and myosin function

Answer 8

proteins in the myofibril (smallest unit of skeletal muscle)

actin forms thin filaments and myosin forms thick filaments

They overlap in sarcomeres

Question 9

What occurs during contraction

Answer 9

thin and thick filaments slide across each other, drawing the Z lines of each sarcomere closer together and shortening the length of the muscle cell

Question 10

myosin function in movement

Answer 10

enzyme that uses ATP energy to create movement, contains a head and tail

Question 11

contractile cycle steps

Answer 11

1. binding of myosin head to myosin binding site on actin. Myosin has ADP and P bound at this point
2. power stroke, myosin head moves to low energy conformation and pulls actin chain towards center of sarcomere, releasing ADP
3. binding of new ATP molecule necessary for release of actin by myosin head
4. ATP hydrolysis occurs and myosin head is set in high energy conformation (cocked)

Question 12

troponin tropomyosin complex

Answer 12

part of thin filament, prevents contraction when Ca2+ isn’t present

troponin is bound to tropomyosin and can bind Ca2+, causing myosin heads to be able to attach to actin, since tropomyosin is moved out of the way

Question 13

neuromuscular junction

Answer 13

synapse between an axon terminus and a myofiber

Question 14

What occurs when ACh binds to its receptor?

Answer 14

A postsynaptic sodium influx causing depolarization, which leads to an end plate potential.

Question 15

What is required for contraction to occur in the myofibril

Answer 15

Action potential has to depolarize the entire myofiber

Question 16

transverse tubules

Answer 16

allow action potential to travel in to thick myofibers.

Question 17

sarcoplasmic reticulum

Answer 17

membrane in the myofiber that releases Ca2+ upon depolarization

Question 18

How does the nervous system increase force of contraction

Answer 18

motor unit recruitment and frequency summation

Question 19

length tension relationship

Answer 19

a muscle contracts most forcefully at an optimum length

Question 20

creatine phosphate function

Answer 20

intermediate term energy storage molecule thats hydrolysis drives regeneration of ATP from ADP + P

Question 21

myoglobin

Answer 21

provides an oxygen reserve by taking O2 from hemoglobin and then releasing it as needed

Question 22

cause of rigor mortis

Answer 22

myosin heads are unable to release actin without ATP and the muscle can neither contract nor relax

Question 23

slow twitch vs fast twitch muscle

Answer 23

slow twitch have a slow speed of contraction and many mitochondria, are very resistant to fatigue

fast twitch includes two types, IIA and IIB. IIB is known as white fast twitch and has very fast contraction, very few mitochondria, and has low fatigue resistance.

Question 24

how is cardiac muscle similar to skeletal muscle

Answer 24

1. thick and thin filaments are organized into sarcomeres, so both cardiac and skeletal muscle are striated
2. t tubules are present and serve the same function
3. troponin tropomyosin regulates contraction in the same way
4. length tension relationship works the same way and is more significant in cardiac muscle

Question 25

How is cardiac muscle different from skeletal muscle

Answer 25

1. muscle cells of the heart are interconnected by gap junctions known as intercalated disks
2. some of the calcium required for cardiac muscle cell contraction comes from the extracellular environment
3. cardiac muscle contract doesn’t depend on stimulation by motor neurons
4. action potential in cardiac muscle depends also on slow voltage gated calcium channels, resulting in the cardiac action potential having a distinctive plateau

Question 26

How is smooth muscle similar to skeletal muscle

Answer 26

contraction is accomplished blsliding of actin and myosin filaments and the four step contractile cycle is the same

Question 27

How is smooth muscle different from skeletal muscle

Answer 27

1. Smooth muscles are narrower and shorter
2. t tubules aren’t needed
3. both smooth and cardiac muscle are connected to neighbors by gap junctions
4. thick and thin filaments aren’t organized into sarcomeres in smooth muscle
5. contraction regulated by calmodulin and myosin light chain kinase
6. Smooth muscle relies heavily on extracellular stores of Ca2+ for contraction
7. Action potential of smooth muscles is determined by slow channels only
8. smooth muscles have a constantly fluctuating resting potential. These slow waves then reach threshold and undergo an action potential
9. smooth muscle are innervated by autonomic motor neurons, while skeletal is innervated by somatic motor neurons

Question 28

role of endoskeleton

Answer 28

1. supports body
2. provides framework for movement
3. protects vital organs
4. stores calcium
5. hematopoiesis (synthesizing formed elements of the blood)

Question 29

axial and appendicular endoskeleton

Answer 29

axial consists of the skull, the vertebral column, and the rib cage

all other bones are part of appendicular skeleton

Question 30

connective tissue

Answer 30

consists of cells and the materials they secrete, derived from fibroblast

Question 31

loose vs dense connective tissue

Answer 31

loose - packing tissues

dense - contains large amounts of fibers such as tendons, ligaments, cartilage, and bone

Question 32

flat vs long bones

Answer 32

flat are the location of hematopoiesis and are important for organ protection

long are important for support and movement

Question 33

red vs yellow marrow

Answer 33

red marrow is found in spongy bone within flat bones and is the site of hematopoiesis

yellow marrow is found in shafts of long bone and is filled with fat and inactive

Question 34

osteocyte function in compact bone

Answer 34

found in each lacuna

allows cells to exchange nutrients and waste by extending down into canaliculi and contacting other osteocytes through gap junctions

Question 35

cartilage

Answer 35

strong but very flexible extracellular tissue secreted by cells called chondrocytes

Question 36

four types of cartilage

Answer 36

hyaline - strong and somewhat flexible
articular - joints lined by hyaline cartilage
elastic cartilage - provides elasticity
fibrous cartilage - very rigid

Question 37

synovial fluid function

Answer 37

lubricates movable joints

Question 38

intramembranous ossification

Answer 38

synthesis of bone from an embryonic tissue called mesenchyme

Question 39

osteoblasts

Answer 39

make bone by laying down collagen and hydroxyapatite

Question 40

osteoclasts

Answer 40

destroy bone by dissolving hydroxyapatite crystals, stimulated by parathyroid hormone and inhibited by calcitonin

Question 41

effect of PTH and calcitriol

Answer 41

increase in blood calcium levels