6: Lecture 14 Terrestrial Locomotion Locomotion In Fluid

Front 1

In mammals we also see the incorporation of the ___ as a limb element. The sprawled posture by many amphibians and reptile requires a lot of energy to maintain and this is helped by having rigidly fixed ______ . In reptiles the scapula is attacted to the ____ by having a ____, _____, & _____.

Back 1

scapula; limb girdles; sternum; substantial coracoid, clavicle, and interclavicles

Front 2

In the permanent push up position, the ______has to be working constantly to adduct the formlimbs and keep the body up off the ground and so the chest has to form a rigid strut to transmit that force to the limbs.

In mammals, the limbs are rotated under the body, so the ________ is freed from this role as a strut for the adductors to work against

Back 2

pectoral musculature, pectoral girdle

Front 3

What is lost in the mammals?
In cursorial specialists, the _____ is lost or reduced

(cursorial: adapted to or specialized for running)

Back 3

coracoid; clavicle

Front 4

For mammals the body is support by the connection of the scapula with the sternum. t or f

Back 4

False. The scapula now has NO bony connection with sternum and it supports the body by a MUSCULAR SLING

Front 5

What does the muscular sling mostly consist of?

Back 5

the serratus ventralis muscles, but is also supported by the rhomboids, trapezius, perctoralis groups

Front 6

Describe how the scapula location after it has been rotated in cursorial species

What is the result of the scapula being freed from its connection with the sternum and oriented in the direction of movement?

Back 6

The scapula is rotated in cursorial species so that the gleniod fossa points more ventrally and the blade of the scapula is in a parasagittal plane.

-it now begins to function as yet another limb segment

Front 7

what is the purpose of incorporating flexion and extension of the vertebral column, as is seen particularly in felids such as the cheetah

Back 7

it is the final way of increasing the stride length

Front 8

The ability to incorporate ______ movements in the direction of travel is a benefit over the lateral undulations seen in reptile, which are _____ to the direction of travel

Back 8

spinal movements, perpendicular

Front 9

What is modified in the cheetahs to allow them to increase their stride length by up to 20%

how does this differ from ungulates, such as the hourse?

Back 9

modifications to the orientation of the ZYGAPOPHYSES

ungulates such as the hours tend to keep their trucks more rigid while running

read paragraph 3 of pg 1 on lecture 14 terrestrial locomotion/locomotion in fluid

Front 10

What is the cost associated with lengthening the limbs ?

Back 10

it becomes more energetically expensive to oscillate them

Front 11

We have been considering the forces to be point forces- applied in one single location. When dealing with a mass that is distributed throughout the lever, you have to consider a quantity called the ______.

Back 11

moment of inertia

Front 12

How do you compute moment of inertia, what is it equal to?

Back 12

computed by divided the limb into many small segments going from proximal to distal

equal to the mass of each segment X the square of the distance from that segment to the center of rotation .

Front 13

Moment of inertia is = mass of each segment X the square of the distance from that segment to the center of rotation.

This means that the mass farther away from the center of rotation has a ______ effect on the moment of inertia, and makes it ______energically expensive to move the limb

Back 13

disproportionate effect; more energetically expensive

Front 14

lengthening the limbs comes at cost...its becomes more energetically expensive to oscillate them, how is this effect moderated?

Back 14

by making the distal limb segments as slender as possible while still being able to withstand the forces applied to them

*it is also minimized by the placement of muscles proximally, usually with long tendons running through the more distal segments

Front 15

What is the energy exchange mechanism that is used in walking?

Back 15

inverted pendulum

Front 16

When humans walk, our center of mass is at its _____ point as we push off from the ground and begin the stance phase. The center of mass then rises as it vaults over a relatively stiff limb and reaches a ___ in the middle of the stance phase. It then falls again to its ___ point as we fall forward over the stance leg and land on the other foot.

Back 16

lower point; maximum; lowest point

Front 17

The speed is at its ____ as we push off from the ground and gradually ____ as we lift ourselves up against gravity, reaches its ____point in the middle of the stance phase, then _____again as we fall forward under gravity.

Back 17

greatest; decreases;lowest; increases

Front 18

because of gravitational potential energy (energy due to height) and kinetic energy ( energy due to speed) oscillate out of phase with one another, they are constantly _____as we walk, so that the energy provided by falling under gravity during the last half of stance is used to raise the center of mass during the first halt of the next stride, and the _____energy gained by this is converted back to ______energy as the center of mass falls again

Back 18

exchanged; gravitational potential energy; kinetic energy

Front 19

what is another means of reducing the energetic cost of locomotion during running?

Back 19

by storing energy in the elastic elements of the muscles and releasing it in the next propulsive cycle.

Front 20

Kangaroos reduce the energetic cost of locomotion by storing energy in the elastic elements of the muscles and releasing it in the next propulsive cycle.
(last paragraph on pg2)
it has been found in hopping kangaroos that the energetic cost of hopping does not increase with increasing speed and that mothers that are carrying joeys also incur no increase in cost of locomotion. t or f

Back 20

true. it is all made up for by increasing the stretch in the tendons due to the greater landing impact, then using that stored energy to generate power.

Front 21

what are fluids?

Back 21

gases and liquids; they share properties not shared by solids

Front 22

unless the a force is great enough to fracture a solid, it will not always return to its original shape. t or f

Back 22

false; it will always return to its original shape

solids resist deformation

PRINCIPLE OF ELASTICITY

Front 23

fluids flow in response to applied forces. Do they resist the change in shape

Back 23

no

they do offer resistance, however, and we say that fluids resist the rate of deformation

Front 24

____ still applies in fluid.

Back 24

newtons 2nd law

Front 25

In any kind of locomotion what two forces are required?

Back 25

vertical and horizontal

Front 26

In the case of terrestrial locomotion, what is the upward force used for?
what is the backward force used for?

Swimming and flying animals, move through a 3 demential space _______a fluid medium that reacts in very different ways than a solid substrate

Back 26

upward force to resist the downward pull of gravity; backward force force to push the animal forward.

pushing against

Front 27

Any swimming or flying animal will encounter resistance from the fluid they are in that tends to impede their forward progress. What is this force called

Back 27

drag

Front 28

Kangaroos reduce the energetic cost of locomotion by storing energy in the elastic elements of the muscles and releasing it in the next propulsive cycle.
(last paragraph on pg2)
it has been found in hopping kangaroos that the energetic cost of hopping does not increase with increasing speed and that mothers that are carrying joeys also incur no increase in cost of locomotion. t or f

Back 28

true. it is all made up for by increasing the stretch in the tendons due to the greater landing impact, then using that stored energy to generate power.

Front 29

define drag

Back 29

a force that acts parallel and opposite the direction of travel

Front 30

what are fluids?

Back 30

gases and liquids; they share properties not shared by solids

Front 31

what force do animals generate to overcome the force of drag?

Back 31

thrust; a force that pushes the animal forward in the direction it is going

Front 32

unless the a force is great enough to fracture a solid, it will not always return to its original shape. t or f

Back 32

false; it will always return to its original shape

solids resist deformation

PRINCIPLE OF ELASTICITY

Front 33

fluids flow in response to applied forces. Do they resist the change in shape

Back 33

no

they do offer resistance, however, and we say that fluids resist the rate of deformation

Front 34

____ still applies in fluid.

Back 34

newtons 2nd law

Front 35

In any kind of locomotion what two forces are required?

Back 35

vertical and horizontal

Front 36

In the case of terrestrial locomotion, what is the upward force used for?
what is the backward force used for?

Swimming and flying animals, move through a 3 demential space _______a fluid medium that reacts in very different ways than a solid substrate

Back 36

upward force to resist the downward pull of gravity; backward force force to push the animal forward.

pushing against

Front 37

Any swimming or flying animal will encounter resistance from the fluid they are in that tends to impede their forward progress. What is this force called

Back 37

drag

Front 38

define drag

Back 38

a force that acts parallel and opposite the direction of travel

Front 39

what force do animals generate to overcome the force of drag?

Back 39

thrust; a force that pushes the animal forward in the direction it is going

Front 40

What are the two possible upward forces

Back 40

buoyancy & Lift

Front 41

____is a force that results from the displacement of the fluid by the animal and depends on the difference in density between the fluid and the animals

Back 41

buoyancy

Front 42

buoyancy always acts ____with respect to the earth, regardless of the direction of travel by the animal

Back 42

vertically upward

Front 43

___ is a force perpendicular to the direction of travel

see aerodynamics definition

Back 43

lift

Front 44

that main downward for is ____and it always operates vertically downward with respect to the earth

Back 44

gravity

Front 45

In some cases, particularly with swimming birds and mammals, the buoyant force exceeds the gravitational force and to stay submerged they have to generate a force that pushes them downward. What is the force called

Back 45

downwardly-directed force

Front 46

what force tends to retard forward progress

Back 46

drag

Front 47

what are the two physical phenomena that cause drag?

Back 47

skin friction or friction drag & pressure drag

Front 48

Which form of drag results of the viscosity of the fluid

Back 48

skin friction

Front 49

which form of drag results from the disruption of the fluid as it is forced to separate and move around the animal as it moves through

Back 49

pressure drag

Front 50

define viscosity

Back 50

is the tendency for fluid molecules to want to stick together and do what their neighbors are doing.

Front 51

The more fluid disturbed, the _____the drag

Back 51

greater

Front 52

The fluid directly adjacent to the surface of the animal travels along the animal at the same velocity.

Whereas; fluid at the distance from the animal has zero velocity

There is a region in between called the __________ where layers of fluid are being sheared past each other and cant move in the same was as their neighbors and generates resistance or drag

This occurs over the entire area the animals exposed to the fluid, so its magnitude depends on the total surface area of the animal, ofter referred to as the ?

Back 52

boundary layer
wetted area

Front 53

The second form of drag is called pressure drag because the disturbance causes a ____pressure anteriorly, where the molecules of the fluid collide with, and have to move around the front end, and a ____pressure behind where the space behind the object has been vacated because it is blocked by the object.

Back 53

high; low

Front 54

How is difference in pressure minimized ?

Back 54

streamlining; by streamlining so that the flow separates smoothly around the front end and tapers gradually posteriorly so there is minimal disruption to the fluid.