Class XXI - Tissues and organ systems III Sensory receptors

Transcription

1 Class XXI - Tissues and organ systems III Sensory receptors

2 0 ms 1 ms 2 ms 4 ms

3 Communication at the Synaps or the dendrite of another neuron Fig. 23-4

4 Cells of the organs which help us sense environmental alterations generate action potentials

5 L & 23-6 Resting potential

6 L Exocytosis of neurotransmitters is the method used by all sensory cells to induce the generation of an action potential at the post synaptic nerve.

7 All senses originate from a receptor cell and are transmitted as action potentials via neurons to the CNS 1. Chemoreceptors -Taste -Smell 2. Mechanosensory receptors - Sense of balance - Sound perception - Sense of pain - Sense of heat - Sense of physical orientation 3. Electromagnetic receptors - Photo receptors

8 Senses: 1. Chemoreceptors (Taste)

9 Senses: 1. Chemoreceptors (Taste)

10 Senses: 1. Chemoreceptors (Taste) L Afferent neurons Synaptic vesicles

11 Senses: 1. Chemoreceptors (Taste) L increase in Na +, H +, or K + causes cell depolarization L

12 Senses: 1. Chemoreceptors (Taste) L K + Ca ++ L

13 Senses: 1. Chemoreceptors (Taste) Fig (Campbell 5 th Ed.)

14 Senses: 1. Chemoreceptors (Taste) Fig (Campbell 5 th Ed.)

15 Senses: 1. Chemoreceptors (Smell) Fig Drosophila: ~60 Humans: ~300 Mouse: ~1500 L

16 Senses: 2. Mechanosensory receptors e.g. Sensing of osmotic pressure A model of Escherichia coli mechanosensitive channel MscL. Sukharev et al. Trends in Neurosciences 27: 345 (2004)

17 Senses: 2. Mechanosensory receptors Hair cells of the ear Fig. 29.3b (Campbell 5 th ed.)

18 Senses: 2. Mechanosensory receptors Hair cells of the ear Semicircular canals L

19 Senses: 2. Mechanosensory receptors Hair cells of the ear

20 Senses: 2. Mechanosensory receptors Hair cells of the ear

21 Senses: 2. Mechanosensory receptors Hair cells of the ear ~ 2 μm L ~ 2 μm

22 Senses: 2. Mechanosensory receptors Hair cells of the ear L L

23 Senses: 2. Mechanosensory receptors Hair cells of the ear L

24 Senses: 2. Mechanosensory receptors Hair cells of the ear K + Gillespie et al. Cell 139: 33 (2009)

25 Senses: 2. Mechanosensory receptors Hair cells of the ear Tether-model Tension-model Gillespie et al. Cell 139: 33 (2009)

26 Senses: 2. Mechanosensory receptors Hair cells of the ear Ca ++ Ca ++ Ca ++ Fig (Silverton Human Physiology, 4 th Ed.)

27 Senses: 2. Mechanosensory receptors Hair cells of the ear Fig (Campbell 5 th ed.)

28 Senses: 2. Mechanosensory receptors Hair cells of the ear direction of container swirl (body movement) container (semicircular canal) liquid

29 Senses: 2. Mechanosensory receptors Other examples Tsunozaki et al. Current Opinion in Neurobiology 19: 362 (2009)

30 L Senses: 3. Electromagnetic receptors Photoreceptors

31 Senses: 3. Electromagnetic receptors Photoreceptors L L

32 Senses: 3. Electromagnetic receptors Photoreceptors L

33 Active pump -30mV + Senses: 3. Electromagnetic receptors Photoreceptors No light cgmp gated channel -60mV + neurotransmitter release Light Rod cell -70mV Brain perceives nothing -70mV Brain perceives light

34 Processing of sense-receptor-generated action potentials L

35 Processing of sense-receptor-generated action potentials Fig (Campbell 5 th ed.)

36 Processing of sense-receptor-generated action potentials (simple reflex) Fig (Campbell 5 th ed.)

37 Processing of sense-receptor-generated action potentials (complex reflex)

38 Required reading: Chapters: Legends to figures and explanations associated with figures covered in class Suggested reading: webcontent/animations/content/soundtransduction.html

39 1. What are examples to types of cells that can generate action potentials? Where exactly in the body are they located? 2. What are the common mechanisms by which a cell can generate an action potential? 3. There are animals that live in total darkness. One of these is a fish that is totally white and has no eyes. Yet it never hits an object in water and can catch its prey. What type of receptor does this fish use to recognize its surroundings-to which human sense receptor is this receptor most similar to? ( 4. There is evidence that magnetoreceptors recognizing the presence of magnetic fields exist in a wide range of organisms. Please identify 2 such receptors that are known to exist in animals. If you wanted to test if these receptors are active in the way they are expected to be, how could you show this in the laboratory? Please think how you would design this experiment.