Presentation is loading. Please wait.

Presentation is loading. Please wait.

Movement on land. Movement lectures nOn Land nIn water nInsect singing nFlight nMuscle PowerPoint now on line u musclelectures.html.

Similar presentations


Presentation on theme: "Movement on land. Movement lectures nOn Land nIn water nInsect singing nFlight nMuscle PowerPoint now on line u musclelectures.html."— Presentation transcript:

1 Movement on land

2 Movement lectures nOn Land nIn water nInsect singing nFlight nMuscle PowerPoint now on line u musclelectures.html

3 Planned Assessment nExam u Short answer 4/6 (2 Neural, 2 Movement) u Paper 1/4 u take in F handouts F own handwriting F clean, unmarked copies of SET papers u Past paper for 2005 has same format

4 Books, CDs nMcNeill - Alexander R. u Animal mechanics u How Animals Move [CD Rom borrow in teaching] nSchmidt-Nielsen (1997) Animal physiology 5 th edition

5 Aim nStaying still u resistance reflex nWalking - and running u neural control u energetics u mechanics u coordination

6 Muscle spindle nmain sense organ used maintain constant position nModified muscle cell innervated by  motoneurons and Ia afferents

7 Resistance reflex nexcitatory loop from muscle spindle Ia afferent

8 Schematic

9 Resistance reflex - 2 ninhibitory loop from muscle spindle to antagonistic muscle nneeds interposed interneuron interneuron

10 Active movement Primary motor cortex nin active movement, if a load is present, resistance reflex adds to motor command to make a stronger movement

11 Summary so far nresistance reflexes provide for stability nfeedback loop

12 Central control nCentral pattern generator (CPG) u Block sensory input (deafferentation) Stick insect: innervated denervated

13 CPG nLocusts flying, Clione swimming, tadpole swimming … nReciprocal inhibition excitation CPG

14 Role of sensory input nwhy have sensory input if CPG works anyway? u initiate/end rhythm u adjust speed of rhythm u cycle by cycle feedback u adjust pattern (gait) nexamples from crustacean stomatogastric ganglion u ~40 neurons

15 Cycle by cycle feedback nSwitch from stance to swing

16 Initiate/end rhythm nSimple : rhythm runs while stimulus is maintained

17 Accelerate rhythm nMore complex : rhythm runs on after stimulus is maintained

18 Babinski reflex Healthy adult reflex - curl toes Infant & damaged CNS spread toes

19 Reflex reversal Stimulate brain (MLR) to induce locomotion Zap Ia interneuron afferent Record motoneuron

20 Summary so far nresistance reflexes provide for stability u feedback loop nCentral pattern generation u Sensory control

21 Generating force n=mass x acceleration nmeasured in Newtons nforce delayed by elastic elements

22 Muscles helped by Levers ntorque : force x distance

23 3 types nForce / fulcrum / load nClass 3 most common nEach muscle contraction moves limb further than muscle contracts

24 Hind legs more powerful npush back on the ground, lift up tail (balance) nsome animals avoid using their front legs u T rex u kangaroos

25 Power nrate of working nwork = force x distance ntherefore power = force x speed nmeasured in u Watts u litres O 2 / kg /hour nat rest, basic metabolic rate

26 Metabolic rate nbasal metabolic rate ndetermine from u food ingested  u heat produced  u oxygen consumed n70 W (1 light bulb)

27 Limits to power output n<1sec 4500 W muscle output n<2 min 1500 W anaerobic energy store u kettle n<2 hours 350 W oxygen transport nAll day 150W need to eat/sleep u 2 light bulbs

28 Walking and running nYou use more energy u going faster u uphill 1 kW 5 miles / hour

29 Going uphill nExtra work is force x distance up n=10 J/kg nif muscle efficiency is 20%, need 50J/kg

30 Going faster... nmore energy need to go faster for most mammals u horse

31 Going faster nsame (per kilo) for all animals npercentage increase less for small animals u larger BMR

32 Per meter? nit might be the energy needed to move a particular distance

33 Summary so far nresistance reflexes provide for stability u feedback loop nCentral pattern generation nLevers help & hinder nenergy use increases with speed and gradient

34 Why do we run? nto keep foot on ground, circular acceleration must be less than gravity u speed ^2 < gravity * radius u speed <  ( gravity * radius ) u speed <  ( 9.8 * 0.9) = 3m/s

35 When do we run? nThis gives us the Froude Number u F = speed ^2/(gravity * leg length) u at 0.5 walk -> run [trot] u at 2.5 trot -> gallop nGravity on moon 5 times less nChildren run sooner as they have shorter legs

36 In running nenergy changes between u potential energy u elastic strain energy nAchilles tendon u stretches by 5% u gives back 93% Achilles tendon

37 In galloping nsecond spring u flexing the spinal cord F with tendon above

38 And Kangaroos hop... nelastically

39 Summary nresistance reflexes provide for stability u feedback loop nCentral pattern generation nLevers help & hinder nenergy use increases with speed and gradient, but stays fixed per meter ntake off for running determined by gravity and leg length nin running, energy stored in tendons


Download ppt "Movement on land. Movement lectures nOn Land nIn water nInsect singing nFlight nMuscle PowerPoint now on line u musclelectures.html."

Similar presentations


Ads by Google