Lecture 15 - Locomotion Flashcards Preview

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Flashcards in Lecture 15 - Locomotion Deck (57):
1

What are three environmental medias?

Air, water, and land

2

What does the high density of water cause?

Drag is a challenge but gravity is not

3

What is the biggest challenge of land and air?

resisting gravity is a problem but drag is not

4

What is newtons first law?

Every object in motion will stay in motion unless external force is applied

5

What is newtons second law?

F = ma, accleration and force are vectors

6

What is newtons thirds law?

Every action has an equal and opposite reaction

7

What is GRF?

Ground force reaction

8

What id ground force reaction?

when the limb contacts the ground it is the force that it experiences

9

What the components of GRF?

Vertical, horizontal, and medio-lateral

10

What does the vertical component do?

support the animals weight

11

What does G(h) and G (ml) allow for?

acceleration/deceleration, maneuvering, and balancing

12

What must occur over a series of strides with the average vertical force?

Must equal the animals weight

13

At rest, what must the force on a limb equal?

weight/n (n= # of limbs)

14

What is a gait?

Pattern of locomotion

15

What are the phases of a gait?

support and swing phase

16

What is a stride?

one full cycle of support and swing phases

17

What is a duty cycle?

relative fraction of stride period represented by limb's support phase

18

What is required to maintain equilibrium?

Increase in maximum forces exerted against ground (Gv = W)

19

How does locomotion proceed?

By repetitively throwing CG forward and then catching it

20

What are cursorial quadrupeds built for?

Forward locomotion

21

Where is the normal center of gravity in located where in cursorial quadrupeds?

Just caudal to thoracic limbs

22

What direction is the center of gravity shifted when head and neck are lowered?

Forward

23

What direction is the center of gravity shifted when head and neck are raising?

Backward

24

What direction is the center of gravity shifted when head and neck are turned to the side?

Laterally

25

What does the tail do?

Contributes to longitudinal and lateral shifts in GC

26

What features decided whether a tail has any effect on GC?

mass and length

27

What are two groups of gaits?

Asymmetric and symmetric

28

What is a symmetric gait?

Movement of limbs on one side repeat motions on other side with intervals between foot falls being evenly spaced

29

What is an asymmetric gait?

Limb movements on one side do not repeat those on other side and foot falls are unevenly space

30

What is a symmetric gait?

Walking

31

What is an asymmetric gait?

Galloping

32

What is forward motion normally started by?

One of the hind limbs, shifts CG forward toward contralateral limb

33

What happens at a slow gait with oscillation?

CG rhythmically oscillates left and right trunks. Tail, head, and trunk swing side to side

34

What happens with rapid gaits with oscillation?

forward momentum and inertia are increased, less lateral oscillation

35

What happens to foot placement with increasing speed?

Fewer limbs provide simultaneous support, placement becomes more medial to maintain balance

36

What is EMA?

Effective limb mechanical advantage

37

What does EMA show?

Ratio of muscles moment arm (r) to moment arm of GRF (R)

38

What is limb mechanical advantage?

Ground reaction force acting on limb relative to limb's posture during support

39

What does limb mechanical advantage determine?

moments, or torques, developed at the joints of the limb

40

What can cause EMA to increase?

Increasing size of animal

41

What is the posture of larger cursorial mammals when they run?

More upright

42

What do larger animals run more upright?

Align joints with GRF, increase mechanical advantage, and reduce magnitude of forces against bones and muscles

43

What is mechanical work?

Physical work of the animal to maintain oscillations in PE and KE

44

What is PE?

Potential energy, energy supplied by muscles to raise and lower body's center of mass

45

What is KE?

Kinetic energy, energy needed to reaccelerate center of mass and limbs

46

What is the affect of the out of phase nature of PE to KE energy during walking?

PE is converted to KE then back, 70% energy exchange which reduces metabolic costs

47

What is the spring mechanism?

Elastic storage of PE and KE in muscles and tendons as the limb lands on ground, is restored back to limb as it is propelled off the ground

48

What occurs with elastic rebound in regards to metabolic cost?

Galloping gaits are metabolically cheaper then trot gait at high speeds

49

What does it mean for something to be metabolically cheaper?

Less oxygen needed

50

What was the pelvic limb adapted for?

Propulsion

51

What was the thoracic limb adapted for?

Support

52

How do thoracic limbs differ from pelvic limbs?

Shorter, straighter, and connect to trunk via fibro-muscular attachments

53

What are the characteristics of the pelvic limbs?

Long, angular, heavily muscled, connected directly to the vertebral column

54

What muscle group assists to elevate CG?

Epaxial muscles

55

Why is the elevation of CG needed?

to extend duration of forward motion which is limited due to the pull of gravity

56

What do the pelvic limbs do to the CG?

Move it forward and upward

57

What do the thoracic limbs provide?

Upward propulsion and directional stability