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Flashcards in Locomotion Deck (41):

Movement and Locomotion
-what they allow
-3 things movement requires

-Movement allows response to stimuli and other important biological processes
-important on gross scale or individ. body parts
-Locamotion: the act of moving from one place to another

Movement requires;
1. Support structure (bones)
2. Contractile tissues (muscles)
3. Control systems (nervous systems)
*interaction of these 3 systems allow co-ordinated movement


Support structures (3)

-Hydraulic systms: fluid filled chambers (is a hydrostatic skeleton)
-e.g. coelomic fluid of earthworm - muscular contractions around space generates movement
-Exoskeleton: Made from cellular secretions (mainly invertebrates)
-e.g. insect cuticle - has hard outer surface
-Endoskeleton - made from cellular secretions (vertebrate bone made of mineralised calcium)
-bones on inside


Vertebrate Skeletons - CT

-what it is and what it does


-CT support and hold together various tissues and organs of an animal's body
-cells are contained in a matrix of non-living material (matrix is what makes them distinct)

e.g. bone, cartilage, blood, loose connective tissue (made of fibres, collagen and elastin)


Vertebrate Skeletons

-what are generally made of (e.gs)

-What cartilage and bone are made of

-Made from specialised CT (cartilage and/or bone)
-terrestrial animals require more robust skeletons
-most are made from proteins such as collagen (bundled, high tensile strength)
-e.g. shells of molluscs (collagen hardened with silicon or calcium salts)
-Insect cuticles - collagen fibres linked together
-Hair, nails and claws
-Cartilage: collagen together w/ elastin and mucopolysaccharides
-Bone: Deposition of calcium and phosphorus salts


Different CT in Vertebrate Skeletons

-Tendon, Cartilage and Bone

-Tendon: Regular, large bundles of collagen
-lots of tensile strength
-muscle to bone
-Cartilage: meshwork of collagen trapping massive sponge-like proteoglycans
-firm but resilient and 'springy'
Bone: Woven collagen sheets trap hard, calcified matrix
-very hard but brittle


Types of cells of CT

Chondrocytes, Osteoblasts, Osteoclasts, Osteocytes

Chondrocytes: cells that produce cartilage
Osteoblasts: Cells that produce bone (mineralise ECM around them)
Osteoclast: Cells that dissolve cartilage and bone
-bones are living; are constantly being remodeled
Osteocyte: Osteoblasts that are surrounded by ossified ECM (maintainance role)


2 Forms of Foetal Bone Development

-bone that forms using these methods

1. Intramembranous Ossification: Bone forms in areas of embryonic mesenchyme
-skull, facial and clavicular bones
2. Endochondral Ossification: Bone replaces embryonic cartilage in axial and appendicular skeleton

Woven bone -> Lamellar bone
*Slow appositional growth and lifelong remodelling


2 Types of Bones

-Blood vessels and osteoblasts

-Compact Bone: Very loosely packed apatite crystals w/ collagen fibres arranged in sheets of lamellae
-Spongy Bone: collagen fibres arranged in all directions; less dense network of apatite crystals
-struts can tell you forces that are acting upon the bone

*Periosteum (outside of bone) is where bone forms - osteoblasts gradually enclose blood vessel and fill to enclose it


Features of Bones

-Forces acting on bones and bodies
-how it affects bones

-Strong, but heavy
-Hollow bones - strong external cortical cylinder, lighter internal framework of struts

Forces: Compression, tension, shear and torsion act on bodies and bones
-The architecture of bone is dictated by the stresses acting upon it


Assymetric Load -> best shape

Best shape when only one plane

-For Assymetric Load: Cyclinder is a robust geometric form that can deal with both tension and compression
-Only one plane: When bone primarily resists bending in only one plane, cylinder is NOT most efficient shape (joists, I-beams)



-3 types and amount of mobility

-Features most mobile joints have to reduce friction and to maintain congruence

Other collagen based bone connections (2)

-Fibrous Joints: are mostly immobile (e.g. bones of skull)
-Cartilaginous joints: allow limited movement (e.g. pubic symphysis)
-Synovial joints: are freely mobile
-To reduce friction: have synovial fluid, articular cartilage
-to maintain congruence: Articular shape, menisci (help distribute weight over bone), ligaments, muscles

Other collagen based Bone connections: Ligaments (bone to bone) and Tendon (muscle to bone)


Lever Mechanics of Locomotion

-Parts of the Lever
-Lever, Fulcrum, Effort, Load

-Lever = rigid rod (bone)
-Fulcrum = fixed point of articulation (joint)
-Effort = force applied to move the lever (muscle)
-Load = Any movement that resists movement of the lever

*Levers can be used to exert a large force over a small distance at one end by exerting only a small force over a greater distance at the other


e.g. of Lever (picking up a rock)

-What mechanism of lever action depends on

-Weight arm and force arm

-Bending arm to pick up rock
-Fulcrum = elbow, rock = load, biceps generate effort

*mechanism of lever action depends on positions of 3 elements
-Weight arm = fulcrum and load
-Force arm = force (load) and fulcrum


Mechanism Advantage

Range of Motion

*what both are proportional to

-Mechanism Advantage: The ration of the load to the effort
-Range of Motion: Is the distance the load is moved

*both are proportional to the distance of the load from the fulcrum


3 Classes of Lever

1. Long force arm and weight arm closer to load= large mechanism advantage
-minimum force to lift large weight E.g. crowbar
2. Load between fulcrum and effort
-can lift a lot e.g. wheelbarrow
3. Least effective in translating muscle force into leverage can move quickly and over large distance
e.g. biceps (insert between elbow and hand)


Lever Mechanics of Locomotion

-Stride length a consequence of range of motion and is proportional to length of the load arm
-limb length
-tend to max length of lever for small muscle contraction = larger movement

-outlevers works well for hopping animals


-What provides power for movement

-Flexion and extension
-Antagonistic muscles

-Locomotion module

-Contractile muscle fibres provide the power for movement (muscles can only contract)
-Flexion: limb bends at a joint
-Extension: Limb straightens
-Antagonistic muscles: separate muscles that induce flexion and extension
-Locomotor module: all muscles responsible for a type of movement (e.g. bird flight muscles)


-Composition of muscle fibres

-Myofibrils & sacromeres
-thin and thick filaments


-Skeletal muscles composed of Muscle fibres (that are bundled in muscle fasicles)
-contain many internal myofibrils
-Myofibrils: formed from a chain of repeating units called sacromeres (striations)
-each has thin filaments (actin) and thick filaments (myosin)
-Sacrolemma: External membrane of muscle cells


Muscles -> how they work

-Energy (form of ATP) causes myosin heads to move along the actin filaments - shortening the myofibrils and contracting the muscle
-attaches via chemical bonds


Force versus Speed

-effect of length and width of muscles

-Forces versus Speed
-each sacromere contracts at the same rate -> long muscles shorten faster and further than short ones
-Each sacromeres contracts with the same force, thick muscles are more powerful than thin ones

*If you lift weights: more sacromeres in width/parallel = force generation


Control of Muscles

-Muscle contraction is controlled by motor nerves which connect to muscle fibres at neuromuscular junction
-voluntary control via CNS
-Synaptic vesicles release neurotransmitters that generate contractions
-at neuromuscular junction
-each muscle fiber has an neuron
-Pattern of muscle activation is called recruitment


2 Types of Skeletal Muscle fiber types

-White: rapid, fatigue
-85% of muscle
-High intestity, burst of energy
-Red: Lots of mitochondria
-Oxidative: lots of mitochondria - use ATP via cellular respiration
-slow, steady cruising
-fuel stores can sustain activity longer
*Transition to land = more complex locomotor muscles ad neuronal control
-Muscles are mosaics of different fiber types


Muscle Metabolism -> Aerobic Metabolism

-Aerobic Metabolism: long term steady state activity and slower
-uses oxygen to generate ATP
-More mitochondria increases aerobic capacity
-high content in oxidative muscles
-Highest in flight muscles of insects and hummingbirds (Half of muscle intracellular volume)
*produces 36 ATP per molecule of glucose


Muscle Metabolism -> Glycolysis

-High intestity activity - rapid movements
-Produces lactic acid (from glycogen)
-muscle exhaustion
-recovery: replenish energy stores -> energy for recovery metabolism is provided by aerobic metabolism
*Produces 2 ATP per molecule glucose


Muscle Metabolism

-types of fuels used

-Type of fuel used changes in response to activity level
-Metabolic transitions are controlled by hormones
-affect production and release from storage tissues
-affect ability of muscles to use the fuels
-Steady-state activity: utilize which fuel is abundant


Main energy source used in low to moderate activity and Sustained activity

-how regulated

-Low to moderate activity
-glucose is main fuel
-controlled by insulin and cortisol -> promote liver glycogen breakdown
-enhance glucose uptake by the muscle
-Sustained activity
-triglycerides become increasingly important
-controlled by lipase which is controlled by corticotropin, epinephrin, norepinephrin and glucagon
-mobilized from muscle and adipose tissues


Oxygen Delivery - diffusion and cardiovascular system

-How Oxygen gets to muscles

-rate of diffusion
-Capillary Tortuousity

-Diffusion: small animals with low metabolic rates, e.g., flatworms
-Cardiovascular system: larger, more active animals

-Rate of diffusions depends on;
-Concentration gradient
-Diffusion distance (capillary density)

-Capillary Tortuousity: Capillaries weaves back and forth across the muscle
-O2 levels decline along capillary - region of muscle may be served by many capillaries


Cursorial Advantage (animals adapted to running far and over landscapes)

-Forage over large arias
-Seek new food sources
-Seasonal variation in food

*important for both predators and prey


Elastic Storage of energy


-Skeletons can store elastic energy
-Potential mechanical energy stored
-occurs through stretching of CT
-When muscles contract, it stretches the CT and bends the bones
-when relaxes, energy can be released to help in locomotion
-recoil in spider's legs can help decrease energy


Moving in the Environment

-2 main environmental factors

-2 main enviro factors;
-Fluid properties (also important for flying animals)
*physiology of locomotion has more to do with the physical environment than the pattern of limb movement


Which forces affect terrestrial animals most

-How aquatic animals deal with this force

-Gravity affects terrestrial animals more than aquatic
-have complex and substantial musculature to compensate
-Aquatic animals benefit from body density that equals that of enviro (buoyancy is the tendency to oppose gravity - upwards force)



e.g. shark

-Animals accumulate lipids to increase buoyancy (are less dense than water)

-Sharks produce lots of triglyercides in liver and cartilage skeleton -> help buoyancy


Fluid Mechanics

-fluid dynamics

-Boundary Layer

-moving through fluid = complex pattern of flow
-Fluid dynamics: rules that describe the movement of a fluid (also applies to air)
-Boundary Layer: Molecular layer of fluid that is influence by the surface of the object - thickness of this layer is dependent on the fluid viscosity

-larger animal = smaller boundary effect
-smaller animal = larger boundary effect


Reducing Drag

-What swimmers and fliers have to overcome (3)

-For an object to move it must overcome drag
-does this by streamlining

-Reduce drag
-Generate lift
-Generating thrust


How Birds generate lift

-How shape and angle of attack affect lift (2)

-wings rounder at frong, curved on top and tapers towards back
-generates a pressure difference
-get pocket of negative pressure behind back = upwards lift
-longer curved surface means greater lift but also greater drag
-high angle of attack also increases lift
-but also need greater velocity to get going


Generating lift (2)


-Aspect Ratio

-Gliding: no metabolic cost - only maintained over short distances but gradually descent towards the ground
-True flight: remain airborne for long periods
-Soaring: using lift from natural air currents to overcome gravity

-Aspect Ratio: length to width
-larger birds have longer, narrower wings to generate enough lift to be efficient


Generating Propulstions

-Propulsion force overcomes drag -> produces vortices (circular pattern of fluid/air)


Propulsion - tails of fish (2)

-Homocercal tail: same top and bottom length
-shape of fins help generate propulsion
-Heteroceral tail (weak) and Heteroceral tail (strong) - adapted for more efficient life rather than propulsion


Cost of Transport (COT)

-what it is

-what related to

-how animals aim to decrease it over different velocities

-metabolic rate/locomoter velocity = ml of O2 per m
-is linearly related to speed
-many animals utilise different styles of movments over different velocities to maximize efficiency (e.g. horse - walk, trot canker and gallop)


Cost of Transport for different types of animals

-Land: must fight effects of gravity (highest COT)
-Air: lift minimizes the effect of gravity
-Swimmers: neutral buoyancy negates the effects of gravity - have the lowest cost of tranport due to buoyancy


Costs of locomotion; Effects of body size

-absolute and relative

-Relative; in water and land/air

-Larger animals use more energy to move because they are larger (in absolute terms)
-In proportion to body mass, small animals use more energy to move a given distance
-locomotion is more economical for large animals than small animals
-Smaller animals in water use more energy because;
-drag increases with surface area - but power increases with muscle mass (MORE SO)
-smaller animals need more uneconomical fast-twitch fibres to move appendages faster
-larger animals can store more elastic energy during movement
-larger muscles and tendons store more elastic energy