muscle structure, function and development

Question 1

where are skeletal muscles located?

Answer 1

-attached to bones, or facial muscles to skin

Question 2

what is the cell shape and appearance of skeletal muscles?

Answer 2

-simple
-very long
-cylindrical
-multinucleate cells with very obvious stritations

Question 3

where are cardiac muscles located?

Answer 3

-walls of the heart

Question 4

what is the cell shape and appearance of cardiac muscles?

Answer 4

-branching chains of cells
-uninucleate
-striatiations
-intercalculated discs

Question 5

where are smooth muscles located?

Answer 5

-walls of hollow organs (other than the heart)

Question 6

what is the cell shape and appearance of smooth muscles?

Answer 6

-single
-fusiform
-uninucleate
-no striations

Question 7

muscle structure

Question 8

muscle function

Answer 8

-produce movement
-maintain posture and body position
-stabilize joints
-generate heat

Question 9

sarcomere

Answer 9

-contractile unit of muscle fibre
-thick filaments contain ATPase enzymes split ATP to release energy for muscle contractions
-myosin heads (cross bridges) link thick and thin filaments during contraction
-sarcoplasmic reticulum (SR) releases calcium to trigger contraction

Question 10

special functional properties of skeletal muscles

Answer 10

-irritability
-contractility
-extensibility
-elasticity

Question 11

irritability

Answer 11

ability to receive and respond to a stimulus

Question 12

contractility

Answer 12

-ability to forcibly shorten when adequate stimulus is received

Question 13

extensibility

Answer 13

-ability of muscle cells to be stretched

Question 14

elasticity

Answer 14

-ability to recoil and resume resting length after stretching

Question 15

what are skeletal muscles stimulated by?

Answer 15

-motor neurons (nerve cells) to contract

Question 16

what are motor units?

Answer 16

-one motor neuron
-all the skeletal muscle cells stimulated by that neuron

Question 17

neuromuscular junction

Question 18

energy for muscle contraction

Answer 18

-direct phosphorylation
-aerobic pathway
-anaerobic pathway

Question 19

direct phosphorylation

Answer 19

-coupled reaction of creatine phosphate and ADP

Question 20

what is the energy source for direct phosphorylation

Answer 20

creatine phosphate

Question 21

does direct phosphorylation use oxygen?

Answer 21

no

Question 22

what are the products of direct phosphorylation?

Answer 22

1 ATP per CP, creatine

Question 23

what is the duration of energy provision for direct phosphorylation?

Answer 23

15 seconds

Question 24

aerobic pathway

Answer 24

aerobic cellular respiration

Question 24

what is the energy source for aerobic pathway?

Answer 24

-glucose -pryruvic acid -free fatty acids from adipose tissue -amino acids from protein catabolism

Question 25

does aerobic pathway use oxygen?

Answer 25

yes

Question 26

what are the products of aerobic pathway?

Answer 26

-32 ATP per glucose -CO2 -H20

Question 27

what is the duration of energy provision for aerobic pathway?

Answer 27

hours

Question 28

anaerobic pathway

Answer 28

-glycolysis and lactic acid formation

Question 29

what is the energy source for anaerobic pathway

Answer 29

glucose

Question 30

does anaerobic pathway use oxygen?

Answer 30

no

Question 31

what are the products of anaerobic pathway?

Answer 31

-2 ATP per glucose -lactic acid

Question 32

what is the duration of energy provision for anaerobic pathway?

Answer 32

40 seconds, or slightly more

Question 33

types of muscle contractions

Answer 33

-isotonic contractions -isometric contractions -muscle tone

Question 34

isotonic contractions

Answer 34

-myofilaments are able to slide past each other during contractions -the muscle shortens, and movement occurs -example: bending the knee, lifting weights, smiling

Question 35

isometric contractions

Answer 35

-muscle filaments are trying t slide, but the msucle is pitted against and immovable object -tension increases, but muscles do not shorten -example: pushing your palms together in front of you

Question 36

muscle tone

Answer 36

-state of continuous partial contractions -result of different motor units being stimulated in a systematic way -muscles remain firm, healthy, and constantly ready for action

Question 37

development of the muscular system

Answer 37

-without exercise, muscles atrophy -with extremely vigorous exercise, muscle hypertrophy -as we age, muscle mass decreases, and muscles become weaker