Locomotion

Question 1

Movement and Locomotion

• what they allow
• 3 things movement requires

Answer 1

• 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

Question 2

Support structures (3)

Answer 2

• 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

Question 3

Vertebrate Skeletons - CT

• what it is and what it does
  e. g.

Answer 3

• 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)

Question 4

Vertebrate Skeletons

• what are generally made of (e.gs)
• What cartilage and bone are made of

Answer 4

• 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

Question 5

Different CT in Vertebrate Skeletons

-Tendon, Cartilage and Bone

Answer 5

-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

Question 6

Types of cells of CT

Chondrocytes, Osteoblasts, Osteoclasts, Osteocytes

Answer 6

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)

Question 7

2 Forms of Foetal Bone Development

-bone that forms using these methods

Answer 7

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

Question 8

2 Types of Bones

-Blood vessels and osteoblasts

Answer 8

• 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

Question 9

Features of Bones

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

Answer 9

• 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

Question 10

Assymetric Load -> best shape

Best shape when only one plane

Answer 10

• 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)

Question 11

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)

Answer 11

• 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)

Question 12

Lever Mechanics of Locomotion

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

Answer 12

• 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

Question 13

e. g. of Lever (picking up a rock)
- What mechanism of lever action depends on
- Weight arm and force arm

Answer 13

• 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

Question 14

Mechanism Advantage

Range of Motion

*what both are proportional to

Answer 14

• 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

Question 15

3 Classes of Lever

Answer 15

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)

Question 16

Lever Mechanics of Locomotion

Answer 16

• 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

Question 17

-What provides power for movement

• Flexion and extension
  
  • Antagonistic muscles

-Locomotion module

Answer 17

• 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)

Question 18

-Composition of muscle fibres

• Myofibrils & sacromeres
  - thin and thick filaments

-Sacrolemma

Answer 18

• 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

Question 19

Muscles -> how they work

Answer 19

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

Question 20

Force versus Speed

-effect of length and width of muscles

Answer 20

• 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

Question 21

Control of Muscles

Answer 21

• 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

Question 22

2 Types of Skeletal Muscle fiber types

Answer 22

• 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

Question 23

Muscle Metabolism -> Aerobic Metabolism

Answer 23

• 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

Question 24

Muscle Metabolism -> Glycolysis

Answer 24

• 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

Question 25

Muscle Metabolism -types of fuels used

Answer 25

- 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

Question 26

Main energy source used in low to moderate activity and Sustained activity -how regulated

Answer 26

- 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

Question 27

Oxygen Delivery - diffusion and cardiovascular system -How Oxygen gets to muscles - rate of diffusion - Capillary Tortuousity

Answer 27

- 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

Question 28

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

Answer 28

- Forage over large arias - Seek new food sources - Seasonal variation in food *important for both predators and prey

Question 29

Elastic Storage of energy -benefits

Answer 29

- 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

Question 30

Moving in the Environment -2 main environmental factors

Answer 30

- 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

Question 31

Which forces affect terrestrial animals most -How aquatic animals deal with this force

Answer 31

- 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)

Question 32

Buoyancy e.g. shark

Answer 32

- Animals accumulate lipids to increase buoyancy (are less dense than water) - Sharks produce lots of triglyercides in liver and cartilage skeleton -> help buoyancy

Question 33

Fluid Mechanics - fluid dynamics - Boundary Layer

Answer 33

- 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

Question 34

Reducing Drag -What swimmers and fliers have to overcome (3)

Answer 34

- For an object to move it must overcome drag - does this by streamlining - Reduce drag - Generate lift - Generating thrust

Question 35

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

Answer 35

- 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

Question 36

Generating lift (2) - soaring - Aspect Ratio

Answer 36

- 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

Question 37

Generating Propulstions

Answer 37

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

Question 38

Propulsion - tails of fish (2)

Answer 38

- 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

Question 39

Cost of Transport (COT) - what it is - what related to - how animals aim to decrease it over different velocities

Answer 39

- 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)

Question 40

Cost of Transport for different types of animals

Answer 40

- 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

Question 41

Costs of locomotion; Effects of body size - absolute and relative - Relative; in water and land/air

Answer 41

- 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