Presentation is loading. Please wait.

Presentation is loading. Please wait.

Nerves and Stimuli. Stimulus – any perturbation in an animal’s internal or external environment which results in changes in membrane physiology of a receptor.

Similar presentations


Presentation on theme: "Nerves and Stimuli. Stimulus – any perturbation in an animal’s internal or external environment which results in changes in membrane physiology of a receptor."— Presentation transcript:

1 Nerves and Stimuli

2 Stimulus – any perturbation in an animal’s internal or external environment which results in changes in membrane physiology of a receptor neuron leading to an action potential

3 Nerve Cells

4 axon myelin

5 Nerve Stimulation Membrane Current

6 Action Potential

7 CytosolExtracellular fluid Na + 15 mM K mM Cl mM A mM Na mM K + 5 mM Cl - 10 mM -60 to -70 mV negative

8 Action Potential Sodium (Na + ) ion Potassium (K + ) ion Sodium channel Potassium channel Activation gate Inactivation gate

9 Action Potential 3. Depolarization opens most Na + activation channels. Influx of Na + makes inside of cell +ve. 4. Inactivation channels close & block Na + influx. Activation gates on K + channels open & K + ions leave making cell more -ve. 5. Some K + channels are still open, allowing K + ions to escape and making the cell more -ve. As the K + gates close, the cell returns to its resting state. 1. Resting state - activation gates on K + and Na + channels are closed. 2. Stimulus opens activation gates on some Na + channels. Influx of Na + and depolarization.

10 Synaptic Junctions

11 Receptors -All receptors are designed for signal transduction (the changing of a signal in one modality (chemical, mechanical, thermal etc.) into an action potential in a nerve

12 Chemoreceptors Hamster - taste budMoth antenna

13 Mechano- and chemoreceptors

14 Thermoreceptors

15 Photoreceptors Photosensitive cells - Planaria Compound eye - Arthropods

16 Nerve cells, stimuli and behaviour Tail flip response in crayfish

17 Lateral Giant interneuron (LGI)

18 a. Correlation between nerve firing and response LGI Stimulating electrode Recording electrode Tactile stimulation b. LGI is sufficent for response LGI Stimulating electrode Recording electrode Tactile stimulation LGI Stimulating electrode Recording electrode Tactile stimulation c. Hyperpolarizing nerve Tail flip No tail flip

19 Nerves, Genetics and Behaviour shaker animation Three genes -shaker, hyperkinetic, ether-a-go-go

20 Nerves, Genetics and Behaviour

21 Sodium (Na + ) ion Potassium (K + ) ion Sodium channel Potassium channel Activation gate Inactivation gate

22 Peripheral Processing of Stimuli Worm-catching Toads

23 Peripheral Processing of Stimuli Worm-catching Toads

24 Central Processing Optic Tectum of a Toad

25 Central Filtering – Lesion of the HVc region in Canaries

26 Number of displays elicited Before lesion After lesion Canary song Sparrow song

27 Central Pattern Generator Senses CNS interneuron Effector Muscle Motor Pattern Motor impulse Sensory input Peripheral filtering Central filtering

28 Central Pattern Generators (Motor Pattern Generators)

29 Cockroach – reflex arc Sensory input Nerve impulse

30 Nerves and Stimuli 1. Structure of nerves 2. Polarity of a nerve cell 3. Transmission of an action potential 4. Peripheral filters 5. Central filters 6. Motor pattern generators

31 Moth Ears Noctuid mothArctiid moth

32 Moth Ears

33 Bat Hunting Call

34 Moth Ears

35 A1A1 A1A1 A2A2 A2A2 A x more sensitive than A 2

36 Moth Ears 1) Bat approaches from side A 1 left A 1 right

37 Moth Ears 2) Bat approaches from front -moth moves side-to-side

38 Moth Ears 3) Bat approaches from above or below From above -ears are covered on downstroke -ears are uncovered on upstroke From below -ears are uncovered on both

39

40

41 STIMULI - AN ETHOLOGICAL PERSPECTIVE

42 1.Releasing (or triggering) stimuli 2.Orienting stimuli 3.Priming stimuli 4.Sign stimuli CATEGORIES OF STIMULI

43 Sign stimuli - species specific -release a reaction that is inherited not learned CATEGORIES OF STIMULI

44 Sign Stimuli 1. European robin Red breast releases aggressive behaviour in males

45 Herring Gull -chick pecks at parent’s beak to obtain regurgitated food Cues?? Complex Sign Stimuli

46 Two major cues are involved: 1. Yellow bill2. Red spot on the mandible

47

48 Male Stickleback (Gasterosteus) Red Belly Red Belly + Head Down Posture

49

50 Innate Releasing Mechanisms SIGN STIMULUS receptorCNS IRM Motor pattern Generated No motor pattern generated Match No match Motor output

51 Fixed Action Pattern (FAP) Egg Rolling in a Greylag Goose Egg-rolling video

52 A series of FAP’s can be put into a sequence Female Male 1. Appears -heads up display 2. Zig-zag swim 3. Swims head up to male 4. Swim to nest 5. follows 6. Show nest 7. Enters nest 8. Tremble thrust 9. spawn

53 In reality:Should look like:

54 More Fixed Action Patterns Courtship behaviour of the mallard, Anas platyrhynchos

55 Modal Action Patterns

56 SUPERNORMAL STIMULI

57 Oystercatcher

58 Lorenz’s Hydraulic Model

59 Vacuum activity Time Court live female Court female model Court rolled up towel Court corner of cage

60 Displacement activity


Download ppt "Nerves and Stimuli. Stimulus – any perturbation in an animal’s internal or external environment which results in changes in membrane physiology of a receptor."

Similar presentations


Ads by Google