Chapter 10

Question 1

functions of skeletal muscle

Answer 1

body movement, maintenance of posture (stabilizes joints and maintains body position), protection and support (holds organs in place), regulating elimination of materials (circular sphincters control passage of material at orifices), heat protection

Question 2

characteristics of skeletal muscle tissue

Answer 2

excitability, conductivity, contractility, extensibility, elasticity.

Question 3

excitability

Answer 3

ability to respond to stimulus by changing electrical membrane potential

Question 4

conductivity

Answer 4

involves sending an electrical change down length of membrane

Question 5

contractility

Answer 5

filaments slide past each other for movement

Question 6

extensibility

Answer 6

ability to stretch

Question 7

elasticity

Answer 7

ability to return to normal after stretching or shortening

Question 8

fascicle

Answer 8

a group of muscle fibers. a whole muscle contains many fascicles

Question 9

epimysium

Answer 9

dense irregular ct wrapping whole muscle

Question 10

perimysium

Answer 10

dense irregular ct wrapping fascicle; houses blood vessels and nerves

Question 11

endomysium

Answer 11

areolar ct wrapping individual fiber. provides electrical insulation, capillary support and binding for neighboring cells.

Question 12

tendon

Answer 12

cordlike structure of dense regular ct. attach muscle to bone.

Question 13

aponeurosis

Answer 13

thin, flattened sheet of dense irregular ct. attach muscle to bone

Question 14

deep fascia

Answer 14

dense irregular ct superficial to epimysium. Separates individual muscles; binds muscles with similar functions

Question 15

superficial fascia

Answer 15

areolar and adipose ct superficial to deep fascia. separates muscle from skin

Question 16

sarcoplasm

Answer 16

cytoplasm of muscle fiber, has organelles and contractile proteins

Question 17

sarcolemma

Answer 17

plasma membrane of muscle. Has t-tubules and voltage gated calcium channels.

Question 18

T-tubules

Answer 18

transverse tubules that extend deep into the cell

Question 19

myofibrils

Answer 19

bundles of myofilaments enclosed in sarcoplasmic reticulum. Make up a muscle fiber.

Question 20

sarcoplasmic reticulum

Answer 20

internal membrane complex similar to smooth ER that surrounds a muscle fiber. contains calcium pumps and calcium release channels

Question 21

terminal cisternae

Answer 21

enlarged portions of the sarcoplasmic reticulum surrounding t-tubules

Question 22

triad

Answer 22

two cisternae with a t-tubule in between

Question 23

myofilaments

Answer 23

contractile proteins within myofibrils. Are either thick or thin

Question 24

Thick filaments

Answer 24

consist of bundles of many myosin protein molecules. Myosin heads point towards ends of the filament

Question 25

thin filaments

Answer 25

consists of bundles of myosin protein molecules. twisted strands of F-actin composed of G- actin monomers. G-actin has a myosin binding site where myosin heads attach from the thick filaments. tropomyosin and troponin are also present and are regulatory proteins

Question 26

Z discs

Answer 26

specialized proteins perpendicular to myofilaments that anchor thin filaments. One sarcomere goes from one z disc to another. contain thin filaments, connectin, and accessory proteins

Question 27

I band

Answer 27

on each side of the z line where actin (thin filaments) do not overlap thick (myosin) filaments. Contain thin filaments and connectin

Question 28

A band

Answer 28

entire length of myosin, thick and thin (actin) overlap for a portion of it.

Question 29

H zone

Answer 29

area where only myosin lays

Question 30

m line

Answer 30

middle of a sarcomere containing thick filaments and accessory proteins

Question 31

myoglobin

Answer 31

allows for storage of oxygen used for aerobic atp production in a cell.

Question 32

glycogen

Answer 32

stored for when fuel is needed quickly

Question 33

creatinine phosphate

Answer 33

can quickly give up phosphate to help replenish ATP supply

Question 34

Overview of the 3 events of contraction

Answer 34

1. Ach is released from the synaptic vesicles and binds to Ach receptors on the muscle. 2. Ach binding triggers action potential along the sarcolemma and t-tubules to the sarcoplasmic reticulum, which is stimulated to release Ca+. 3. Ca binds to troponin and triggers sliding of thin filaments past thick filaments causing the muscle to contract.

Question 35

Excitation contraction coupling

Answer 35

When calcium binds to troponin, it moves tropomyosin exposing the myosin binding sites on the actin.

Question 36

Crossbidge cycling

Answer 36

1. Crossbridge forms from myosin head attaching to actin 2. Power stroke occurs when myosin head pulls actin closer together; adp and pí is released 3. Release of head: atp binds to myosin causing it to release from actin 4. Myosin head resets: atp->adp provides energy to “cock” the myosin head

Question 37

Skeletal muscle relaxation

Answer 37

Termination of nerve signal and ach release from motor neuron Hydrolysis of ach by acetylcholinesterase Closure of ach receptors on muscle causing no action potential to be created Calcium channels in sarcoplasmic reticulum close and calcium in the muscle is returned to sr by pumps Troponin and tropomyosin returns to its normal shape Muscle returns to normal shape

Question 38

3 ways to generate additional ATP

Answer 38

Creatine phosphate Glycolysis Aerobic cellular respiration

Question 39

Myokinase

Answer 39

Additional ATP can be rapidly produced this way. A phosphate transfers from one ADP to another to make ATP

Question 40

Creatine phosphate

Answer 40

Contains a high energy bond between creatine and phosphate. Phosphate can be transferred to adp to make atp. It is catalyzed by creatine kinase and gives 10-15 seconds of additional energy

Question 41

Glycolysis

Answer 41

Doesn’t require oxygen. Glucose is converted to 2 pyruvates and 2 atp is released per glucose molecule. Occurs in cytosol

Question 42

Aerobic cellular respiration

Answer 42

Requires oxygen Occurs in mitochondria Pyruvate oxidized to co2 which causes transfer of chemical bond energy to NADH and FADH2. This energy is used to generate ATP by oxidative phosphorylation. Produces 30 ATP Triglycerides can also be used as a fuel to produce ATP

Question 43

Lactate formation

Answer 43

Pyruvate is converted to lactate by lactate dehydrogenase. Lactate can be used as fuel by skeletal muscle or enter blood to be taken up by cardiac muscle or liver.

Question 44

Lactic acid cycle

Answer 44

Cycling of lactate to liver where it is converted to glucose, and transport of glucose back to muscle

Question 45

Type of energy supply when comparing level of exercise

Answer 45

Short (less than 10 sec): phosphate transfer system Less than a minute: glycolysis More than a minute: aerobic processes