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44 Cards in this Set
- Front
- Back
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What is the term that describes how shape changes that help compensate for disproportionate increase in body mass compared to cross sectional areas
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allometry
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How do larger animals deal with the disproportionate increase in mass relative to areas...( another way other that allometry)
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limb posture
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Describe how limb posture differs in small and large animals
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smaller animals tend to stand with their limbs bent to some extent, referred to as a crouched posture. ( the more crouched the posture the smaller the animal tends to be)
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what is the purpose of crouched posture?
-For an animal just standing and supporting its body weight, what is the ground reaction force? -Where does the crouched posture of an animal cause a joint to move in reference to line of action of the force? (farther or closer to it) As a result how does this affect the out lever arm? In contrast, describes what happens when the limb is help straight? |
-the ground reaction force due to the body weight is always vertical and operates near the center of the part of the foot in contact with the ground
-so if an animal is in a crouch posture, this brings the center of the joint farther from the line of action of the force -increasing the out lever arm -if the limb is held straight, the line of action of the out force is much closer to the joint center, so the out lever is much small and the muscles don't have to general as much force to resist it |
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The earliest for of terrestrial locomotion: walking
A complete cycling ______ is called a stride |
of all the feet
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a stride is define as a period between the placement of one foot, usually _____, through the subsequent placement of the _____
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left hind; same foot
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Describe how a complete stride is depicted on on a bar graph with each foot graphed individually
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the parts of the graph where the bar appears is when that is on the ground, and when there is no bar, the foot is off the ground.
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What are the two phases that each step can be broken down into?
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Propulsive stance phase: the period of time when the foot is on the ground, and
a swing phase: when the foot is off the ground and brought forward to initiate the next step |
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the proportion of the stride in which an individual foot is on the ground is called the ___,
is this the same for all four feet?? |
duty factor; same for all four feet
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A duty factor is 50% or greater means that.....
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there is at least one foot on the ground at all times
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what is a term commonly used with reference to locomotion
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gait
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Although there are several possible definitions to define a gait,
(We use) Gait is the particular pattern of foot placements an animal uses during terrestrial locomotion. Gaits are defined by both ____ & ______ |
duty factor and the phase relationship between the placement of the feet
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Gaits can be divided into walking gaits, which share the characteristic of having a duty fat of _____ and running gaits, which include an ______and have duty factors of ______
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50% or greater; aerial phase; less that 50%
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what kind of posture do early tetrapods walkers and living tetrapods have?
These animals tend to be low to the ground, what is a primary concern for them? |
sprawled posture; stability
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why cant early tetrapods with a sprawled posture afford (or at least they try to avoid) turing moments, such as rolling?
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because they are low to the ground they have little time to generate a counter moment to correct it before they are dragging on the ground
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To prevent toppling you have to have you ____ between your supports.
what is the most stable configuration while walking? |
center of mass; tripod, have three points of support
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With ____ support, the _____ can lie anywhere with the triangle of support without generating any ____.
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3 points of support; center of mass; turning moments
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where does the center or mass have in be with two points of support?
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with two points of support, the center of mass has to lie on a line joining them if there are to be no turning moments.
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what does it mean for an animal to be statically stable
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if the center of mass lies within these areas or line of support;
meaning that the animal does not have to take any action to prevent rotations of the body |
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An animal can be ______, meaning that its center of mass can move outside the are of support for a brief period of time durning the stride, but it then catches itself with one or more limbs before it loses its balance
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dynamically stable
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Gaits:
Within broad categories of walking and running, there are a number of different patterns possible. Name two: that gait typically used by mammals & the gait typical led used by primates |
lateral sequence gait; diagonal sequence gait
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what does ipsilateral and contralateral mean
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same side; opposite side
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Name the gait in which a step by the hind foot is followed by the ipsilateral front foot, then the contralateral hind foot followed by contralateral forefoot
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Lateral sequence gait
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Primates are unusual among mammals in that they use a _______while walking, in which the placement of a hind foot is followed by the contralateral front foot, then the contralateral hind foot followed by the ipsilateral front foot.
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diagonal sequence gait
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During a lateral sequence gait there is a period in which the animal is supported by only the two legs that are on the same side of the body...it this stable?
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it is unstable but..fine for a long legged animal walking on a firm ground
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Primates are ______ adapted and tend to be walking on ______ supports. their two legged support phase has the two legs on ____so that the line of support runs across the _____
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arboreally adapted;
narrow their two legged support phase has the two legs ON OPPOSITE SIDES OF THE BODY, so that the line of support runs across the narrow substrate on which it is walking |
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a trot is one of the running gaits. A trot is a _____ gait with left hind and right front in phase, and the right and left front in phase.
Slower trots are possible and have shorter _______. |
diagonal sequence gait; shorter aerial phases
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The ________ is the primary mechanism for increasing the stride length in running gaits.
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aerial phase
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what is the lateral sequence version of the slow run called ?
(horses are trained to do this but the camel family and giraffes are the only animals know to use this gait naturally) |
pace
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In a pace gait the front and hind leg on the same side move together in phase. Both the trot and the pace are called ______. what are they called this
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symmetrical gaits; because movements of the left and right sides of the body are evenly spaced in time
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At greater speeds many animals switch to an _______ gait.
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asymmetrical gait
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the asymmetrical fast gait used by large animals is the gallop. In this gait the two front and two hind limbs come closer to being in phase and each foot has a very low ___
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duty factor
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In the rotary gallop picture, most the stride the body is supported by a single limb, with brief dual support and aerial phases.
Although the aerial phase appears to be short in terms of the time spent, it can actually carry the animal a very great distance and increase the _________ enormously. |
stride length
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what is an asymmetrical gait used by small animals?
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bound or half bound; the hind legs are in phase but the two forelimbs are slightly out of phase. In a bound both hind and forelimbs are in phase.
*there are two aerial phases one extend and one gathered |
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How is the overall speed of animal determined
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stride length times it stride frequency
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In a general sense, what can vertebrate do to increase speed?
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manipulate both of factors of speed (stride length and frequency) to move more quickly
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How do Reptiles move?
How do they typically increase their speed? how is this method of increasing speed limited |
Reptiles use lateral undulations of the body to increase their stride length, but they typically increase their speed by increasing their FREQUENCY
their speed is limited by how quickly they can move their legs, which is limited by the muscle physiology |
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In contrast to Reptiles, Mammals are more likely to change _______ to increase their speed.
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stride length
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_____is defined as the distance traveled by the center of mass in each stride
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stride length
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At a walk, where there is no ____, the extent to which the stride length can be increased is limited by the ____.
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aerial phase; leg length
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At a walk, there is no aerial phase, the extent to which the stride length can be inc. is limited by the leg length. at this point, stride length is inc. by a change in ___to a ______with an aerial phase
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gait; running gait
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Using an aerial phase means that you can basically throw your body forward and travel much further in each stride regardless of what?
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leg length
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Specializations for speed have occurred over evolutionary time.
If you want to increase you maximum stride length, the best way is to lengthen your limbs. What are two ways of doing this? |
1) to elongate the individual limbs segments (we see this in cursorial species, those specialize for running)
2) to increase the number of limb segments that are involved in locomotion. * one method for accomplishing this is incorporating autopodial elements into the limb. |
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Cursorial specialists tend to be __, meaning they have incorporated the metacarpals and metatarsals into the limb and walk on the phalanges, adding one limb segment, or ___, meaning that they walk on the very tips of the distal phalanges, and this adds __ limb segments.
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digitigrade; unguligrade; 2
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