Lecture 15: Muscles and Locomotion (Midterm II)

Question 1

in which manner do muscles act?

Answer 1

in antagonistic pairs; one extends and one that flexes

Question 2

in non-vertebrate animals, there are antagonistic elements but they don’t ________ , they work against each other; this is called ________

Answer 2

attach to a skeletal structure; peristalsis

Question 3

muscle arrangement hierarchy

Answer 3

1. muscle bundles within a muscle
2. muscle fibers within a muscle bundle
3. myofibrils within a muscle fiber
4. sarcomeres within myofibrils

Question 4

the smallest unit of the myofribil is the ____ and called a ____

Answer 4

active part; sarcomere

Question 5

thick vs thin muscle filaments

Answer 5

• thick filaments contain many different myosin molecules lined up in a staggered array
• thin filaments contain two strands of actin and a regulatory protein wrapped around each other

Question 6

what two things interact and how do they interact so that the actin can be pulled inward

Answer 6

actin & myosin must interact so actin can be pulled inward; cross bridges are formed from the myosin to the actin

Question 7

how do the actin and myosin work to make a contraction if the filaments stay the same length?

Answer 7

myosin molecules act like ratchets to pull the actin filaments (thin) past the myosin (thick) filaments so the muscle shortens but the filaments don’t

Question 8

what is a muscle contraction the result of?

Answer 8

a signal that is transmitted to the muscle through an action potential in a motor neuron

Question 9

the signal in muscle contraction goes through which membrane?

Answer 9

sarcoplastic reticulum

Question 10

what are the two regulatory proteins on the binding sites of actin and what is their function

Answer 10

tropomyosin and troponin; they are like gate keepers so the gate isn’t always open

Question 11

What are the four types of muscle fibers and their function

Answer 11

1. tonic fibers: contract very slowly; postural muscles of amphibians, reptiles, and birds
2. slow oxidative: **contract slowly **& fatigue slowly; mammal posture muscles, but also for sustained/repetitive exercise
3. fast oxidative: high energy, activated quickly; rapid repetitive motions and lots of mitochondria for work over long periods
4. fast-twitch glycolytic: contract rapidly, fatigue quickly; largely anaerobic and no sustained activity

Question 12

Types of locomotion and the forces they overcome

Answer 12

1. terrestrial locomotion (walking/running)
   - friction
   - gravity
2. flying
   - drag
   - gravity
3. swimming
   - drag

Question 13

A cost of transport graph shows what

Answer 13

average energy required for a given size animal to travel a specific distance; y axis is transport cost and x is body mass