1. Sensors: Detect Changes in environmental conditions Use Receptor Cells
Sensory Physiology
Sensors:
Detect Changes in environmental conditions
Use Receptor Cells

2. Transduction
Conversion of environmental change into an electrical signal
Receptor responds to stimulus by releasing neurotransmitter to a neuron
Neuron sends message to brain to be interpreted

3. Types of Environmental Stimuli
Chemoreception
Mechanoreception
Photoreception

4. Chemoreception Detection of chemical types and concentrations 2 Types:
1. Taste Receptors
– detects chemicals dissolved in water within the mouth
2. Smell- Olfactory Receptors
– Sense chemicals in the air

5. Taste Buds (Taste Receptors)
MAMMALS, REPTILES, BIRDS:
Allows animal to detect and identify dissolved chemicals
Found mainly on the upper surface of the tongue
Pits found on tongue consist of sensory cells
Every sensory/receptor cell has a tiny hair called a microvilli, that project into the saliva
Chemicals come into contact with these hair receptors
These receptors send messages along nerves to the brain
Flavors are then interpreted

6. Taste buds
microvilli
Sensory Cells
Taste Bud

7. Taste Buds

9. Chemoreceptors- Taste/Smell
INVERTEBRATES:
Use receptors found on Antennae
Use receptors found on Legs/Feet

10. Olfactory Receptors What do animals use their sense of smell for?
Locate Food
Mark Territory
Identify their own offspring
Presence and condition of a potential mate

11. Olfactory Receptors (Distance Receptors)
The organ of smell is the olfactory organ
Located in the nose
Responds/Detects chemicals in the air
Consists of nerve cells that have tiny hairs on the surface
Animal
Breathes
Sense cells respond to molecules
Impulse fired and sent to the brain for interpretation

12. Olfactory Organ
Olfactory Organ
Nerve Fibers

13. Snakes/Lizards Tongues
Tongue collects chemicals then retracts
swab chemicals over vomeronasal organ (Jacobson’s organ)
Chemical/pheromone perception

14. Insect Antennae
Pheromone Reception

15. Mechanoreceptors Detection of Mechanical Energy and Force
– Tactile (touch and pressure)
– Equilibrium (gravity and acceleration)
– Vibrations (sound)

16. Tactile (Touch)
Touch is an important sense because it provides important information about:
Proximity of food
Predators
Environmental features

17. Tactile Receptors Insect Receptors Vertebrate Receptors
Bristle/hair receptors
Vertebrate Receptors
Nerve endings in skin are sensitive to touch and pressure
The roots of hairs may also be well supplied with sensory receptors that inform the animal that it is in contact with an object
Whiskers are modified hairs

18. Whiskers – Tactile Receptors

19. Tactile (Touch)
Tactile receptors are not evenly distributed over the animal's surface.
They are in higher concentration, and therefore closer together, on critical surfaces.

20. Tactile Receptors PAIN:
Receptors that sense pain are found in almost every tissue of the body.
Receptors allow animals to respond to tissues that are dangerously hot, cold, compressed or stretched, or that there is not enough blood flowing into them.

21. General senses in the skin
Pain Receptor
Cold Temperature Receptor
Touch Receptor
Touch Receptor
Pressure Receptor

22. Equilibrium: Hair Cells
located deep inside the ear
They tell you if your head is tilted or if you are standing on your head. (orientation relative to gravity)
vibrations bend “hairs” (stereocilia)
alters release of neurotransmitter to sensory neurons sent to the brain

23. Hair Cells Located in the Inner Ear

24. Equilibrium: Vertebrate Vestibular Organs
Fluid-filled compartments in the inner ear
Semi-circular canals
- Head moves, liquid in canals slosh around and moves the tiny hairs that line each canal
- Hairs translate message into nerve impulses that are sent to the brain
- Brain tells body how to stay balanced

25. Equilibrium: Invertebrate Statocysts
Central statolith stimulates different hair cells based on orientation to gravity

26. Vibration Vertebrate Cochlea
– Elongate structure containing hair cells
– Fluid pressure waves induce vibration of the basilar membrane
– Stimulates hair cells which triggers electrical impulses to the brain.

27. Passage of Sound through the Ear

28. Vibrations: Insect “Ears”
A Frog is a
Vertebrate
Tympanic Organs
Terminal Cerci
Johnston’s organ
– Wind receptor
– May be tuned to specific frequencies
Tympanic Organ

29. Vibrations: Lateral Lines
Fish and aquatic amphibians
Hair cells distributed along lateral line
• Detect vibrations in water and flow of water

30. Photoreceptors VISION: Perception of electromagnetic radiation
Animals are only able to use the visible portion of the electromagnetic spectrum

31. Reception of visual signals
Light enters the eye
specialized cells, photoreceptors, may be stimulated by particles of light
Photoreceptors in the retina are triggered
1. rods - light intensity
2. cones - color
Color perception: brain compares outputs of different photoreceptor types.

32. Parts of the Eye
Cornea: A tough, clear covering over the iris and pupil that helps protect the eye.
Sclera: The thick, tough, white outer covering of the eyeball.
Iris: A muscle that controls how much light enters the eye.
Colored portion of the eye
Aqueous Humor: Fluid that helps the cornea keep its rounded shape.
Pupil: A hole in the center of your iris that allows light in.
Lens: Focuses light on the retina
Vitreous Humor: Thick, clear jelly that helps give the eyeball its shape.
Retina: A layer of photoreceptor cells
Connected to the brain by the optic nerve
Rods: light intensity
Cones: Color

33. The Eye Vitreous Humor Sclera Iris Optic Nerve Cornea Pupil Lens
Tapetum
Retina
Iris

34. Advanced Eyes: Tapetum
Layer of tissue immediately behind the retina
It reflects visible light back through the retina
Increases the light available to the photoreceptors
Provides superior night vision
Found in many vertebrate animals, not humans

35. Time for Eye Dissection!!!!