Locomotion Flashcards
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;
- Support structure (bones)
- Contractile tissues (muscles)
- 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
e. g.
- 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
- e.g. shells of molluscs (collagen hardened with silicon or calcium salts)
- 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
- Intramembranous Ossification: Bone forms in areas of embryonic mesenchyme
- skull, facial and clavicular bones - 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)
Joints
- 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
- To reduce friction: have synovial fluid, articular cartilage
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
- Long force arm and weight arm closer to load= large mechanism advantage
- minimum force to lift large weight E.g. crowbar
- Load between fulcrum and effort
- can lift a lot e.g. wheelbarrow - 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
- limb length
-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
-Sacrolemma
- 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
- glycolytic
- 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 lactic acid (from glycogen)
- 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
- glucose is main fuel
- 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
-benefits
- 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;
- Gravity
- 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)
Buoyancy
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)
- soaring
- 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)
- Land/Air:
- 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
