Page 1: General Function of Sensory Receptors

Sensory Receptors Overview

• Provide critical information about both external and internal environments.

• Respond to various stimuli, ensuring the body can react to changes.

• Each receptor type is specialized for specific stimuli:

  • Eye receptors respond best to light energy.

  • Ear receptors respond best to sound energy.

• Action potentials generated at receptors are conveyed to the Central Nervous System (CNS) for interpretation.

Page 2: General Structure of Sensory Receptors

Receptors and Sensory Neurons

• Sensory receptors send signals to the CNS through sensory neurons.

• Receptive Field: This term refers to the area where a sensory neuron is activated. Smaller receptive fields enable more precise localization of stimuli.

Page 3: Sensory Receptor Classification 1

Classification Overview

• Sensory receptors are categorized based on:

  1. Distribution

  2. Stimulus origin

  3. Modality of stimulus

• Receptor Distribution:

  • General sense receptors: Simple structures found throughout the body.

    • Somatic sensory receptors include tactile receptors in skin and mucous membranes, as well as proprioceptors in joints, muscles, and tendons.

    • Visceral sensory receptors are located in the walls of internal organs, monitoring stretch, chemical environment, temperature, and pain.

  • Special sense receptors are complex and located in specific sense organs in the head, including: olfaction (smell), gustation (taste), vision, audition (hearing), and equilibrium (balance).

Page 4: Sensory Receptor Classification 2

Classification by Stimulus Origin

• Exteroceptors: Detect stimuli from the external environment, found in skin and mucous membranes, including special sense receptors.

• Interoceptors: Monitor stimuli from internal organs, hence found in visceral sensory receptors.

• Proprioceptors: Detect body and limb movements, including somatosensory receptors in muscles, tendons, and joints.

Page 5: Sensory Receptor Structure

Structural Overview

• Sensory receptors can be broadly classified according to their structure and location.

Page 6: Sensory Receptor Classification 3

Classification by Modality of Stimulus

• Five main types of sensory receptors:

  1. Chemoreceptors: Detect chemicals in fluid, including both external (e.g., smell) and internal factors (e.g., blood oxygen levels).

  2. Thermoreceptors: Monitor temperature changes; located in skin and hypothalamus.

  3. Photoreceptors: Respond to changes in light intensity, color, and movement; primarily found in the retina of the eye.

Page 7: Sensory Receptor Classification 4

Continued Classification by Modality of Stimulus

• Continuing from previous classification: 4. Mechanoreceptors: Respond to distortion of cell membranes; detecting touch, pressure, vibration, and stretch. Found as baroreceptors, proprioceptors, and specialized receptors in the inner ear. 5. Nociceptors: Detect painful stimuli, differentiating into somatic nociceptors (sensing external damage) and visceral nociceptors (monitoring internal organ damage).

Page 8: Skin

• Discusses the surface and receptors in the skin, indirectly referencing structural composition.

Page 9: Tactile Receptors

Overview of Tactile Receptors

• Tactile receptors are abundant mechanoreceptors located in skin and mucous membranes.

• These receptor endings may be encapsulated or unencapsulated.

Page 10: Proprioceptors 1

Proprioceptor Function

• Proprioceptors are located in muscles, tendons, and joints.

• These specialized mechanoreceptors relay information regarding body position and movement.

• They adapt slowly (tonic receptors), providing a continuous sense of the body’s position, often referred to as proprioception (the sixth sense).

Page 11: Proprioceptors 2

• Continues to elaborate on proprioceptors with visual aids.

Page 12: Olfaction: The Sense of Smell 1

Overview of Olfaction

• Olfaction refers to detecting odorants—volatile molecules dissolved in air.

• Chemoreceptors in the olfactory epithelium react to these odorants, providing crucial information regarding food, danger, and social cues.

• Humans can distinguish thousands of odors; olfactory epithelium contains various cell types (olfactory receptor cells, supporting cells, basal cells).

Page 13: Olfaction: The Sense of Smell 2

The Structure of Olfactory Epithelium

• The replacement of sensory receptor cells in the olfactory epithelium declines with age.

• Layers include lamina propria, an areolar connective tissue layer that houses blood vessels, nerves, and glands involved in producing mucus.

Page 14: Olfactory Epithelium

Olfactory Structural Overview

• Visual representation of olfactory epithelium.

Page 15: Olfaction: The Sense of Smell 3

Olfactory Receptor Cells and Pathways

• Olfactory receptor cells are primary neurons in the sensory pathway for smell, characterized by a bipolar structure.

• Olfactory hairs are cilia from receptor cells that house specific chemoreceptors for odorants, allowing smell perception based on stimulated cells.

Page 16: Olfaction: The Sense of Smell 5

Mechanism of Smell Detection

• Effects of sniffing or deep breathing to increase odorant binding to receptors.

• Detailed explanation of the biochemical mechanism involving G-proteins, ion channels, and action potentials relating to olfactory sensation.

Page 17: Human Eye

• Introduces the overall structure and function of the human eye.

Page 18: Internal Eye Structures

Visual Representation of Internal Eye Structures

• Contains visual aids of eye anatomy.

Page 19: Accessory Structures of the Eye 1

Accessory Structures Overview

• Accessory structures aid in the eye's functioning, such as extrinsic eye muscles, eyebrows, eyelids, eyelashes, conjunctiva, and lacrimal glands.

• Functions of eyebrows and eyelashes include nonverbal communication and protection of the eye from debris.

Page 20: Accessory Structures of the Eye 3

Detailed Structure of Conjunctiva

• Describes the conjunctiva, its types, and functions, including moisture and nourishment of the eye while safeguarding vision.

Page 21: Clinical View: Eye Infections

Common Eye Infections

• Describes conditions like chalazion, stye, and conjunctivitis, including their causes and symptoms.

Page 22: Accessory Structures of the Eye 4

Lacrimal Apparatus Function

• Explains the lacrimal apparatus, its components, and significance for eye lubrication, cleansing, and protection.

Page 23: Eye Structure 1

Eye Overview

• Provides dimensions and anatomy of the human eye, orientation in the skull, and the role of humor (vitreous and aqueous) in maintaining ocular structure.

Page 24: Tunics of the Eye

Eye Tunics

• Visual representation of the tunics of the eye.

Page 25: Eye Structure 2

Humor Types in the Eye

• Differentiates between vitreous humor in the posterior cavity and aqueous humor in the anterior cavity, outlining each fluid's functions.

Page 26: Eye Structure 3

Aqueous Humor Production

• Explains the production, circulation, and drainage pathways of aqueous humor; significance of drainage failure leading to glaucoma.

Page 27: Clinical View: Glaucoma

Glaucoma Overview

• Discusses glaucoma, its types (angle-closure, open-angle, congenital), and the risks it poses to vision.

Page 28: Eye Structure 4

Function of the Lens

• Lens function discussed as it changes shape to focus light on the retina, including its cellular composition.

Page 29: Eye Structure 5

Fibrous Tunic Explained

• Describes the fibrous tunic of the eye (sclera and cornea), covering their functions and anatomical details.

Page 30: Eye Structure 6

Vascular Tunic Details

• Discusses the vascular tunic of the eye (choroid, ciliary body, iris), emphasizing their roles and anatomical structures.

Page 31: Eye Structure 7

Iris Functionality

• Outlines the structure of the iris, pupil function, and how it regulates light entering the eye.

Page 32: Iris Control of Pupil Diameter

• Visual representation demonstrating how iris muscle contraction affects pupil size.

Page 33: Eye Structure 8

Retina Overview

• Discusses the internal structure of the retina, including the pigmented and neural layers and their functions in photoreception.

Page 34: Eye Structure 9

Retina Cell Layers

• Describes the three sublayers of the retina: photoreceptor layer (rods and cones), bipolar cell layer, and ganglion cell layer.

Page 35: Composition of the Layers of the Retina

• Visual representation of the composition of layers within the retina.

Page 36: Eye Structure 10

Retina's Critical Components

• Details the optic disc and macula lutea area, discussing their significance for vision.

Page 37: Clinical View: Detached Retina

Risks and Symptoms

• Discusses retinal detachment, causes, symptoms, and the risks associated with certain conditions.

Page 38: Clinical View: Macular Degeneration

Condition Overview

• Discusses macular degeneration, its causes, and symptoms affecting vision.

Page 39: Clinical View: Cataracts

Symptoms and Treatment

• Defines cataracts, discusses symptoms, and describes modern surgical treatment options.

Page 40: Clinical View: Functional Visual Impairments 1

Types of Visual Impairments

• Defines emmetropia, hyperopia, and myopia with visual representation and corrective measures.

Page 41: Clinical View: Functional Visual Impairments 2

Additional Visual Impairments

• Discusses astigmatism and presbyopia, noting their characteristics and treatment options.

Page 42: Physiology of Vision: Phototransduction 2

Rods and Cones

• Describes the structural and functional differences between rods and cones, their distribution, and their role in vision.

Page 43: Physiology of Vision: Phototransduction 3

Photopigments Overview

• Discusses photopigments, how they absorb light, and their respective roles in different photoreceptors.

Page 44: Absorption Wavelengths

• Visual representation of absorption wavelengths of photopigments.

Page 45: Clinical View: Color Blindness

Condition Overview

• Explains color blindness, its causes, particularly focusing on red and green distinctions, and its prevalence.

Page 46: Gustation: The Sense of Taste 1

Introduction to Gustation

• Defines gustation and discusses taste buds' structure within the papillae of the tongue.

Page 47: Gustation: The Sense of Taste 2

Papillae Overview

• Describes different types of papillae, their locations, and their function related to taste sensation.

Page 48: Tongue Papillae and Taste Buds

• Visual representation of papillae and taste buds on the tongue.

Page 49: Gustation: The Sense of Taste 6

Basic Taste Sensations

• Overview of the five basic tastes: sweet, salt, sour, bitter, and umami, with specifics regarding their causes and nature.

Page 50: Anatomic Regions of the Right Ear

• Discusses the anatomical structure of the ear with visual representations.

Page 51: Ear Overview

• General overview of the ear's structures and functions.

Page 52: Ear Structure 2

Middle Ear Details

• Details the middle ear's structure, including its components and functions with respect to pressure and sound.

Page 53: Ear Structure 3

Auditory Ossicles

• Describes the three auditory ossicles: malleus, incus, and stapes, their shapes, and their roles in sound transmission.

Page 54: Ear Structure 4

Ossicle Function

• Outlines the function of auditory ossicles in sound amplification and the muscles controlling their movement.

Page 55: Middle Ear

• Visual representation of the anatomical structures of the middle ear.

Page 56: Ear Structure 5

Inner Ear Overview

• Introduces the inner ear's structure and the fluids contained within it.

Page 57: Ear Structure 6

Main Regions of the Inner Ear

• Outlines the composition of the inner ear, encompassing cochlea, vestibule, and semicircular canals.

Page 58: Inner Ear

• Visual representation of the inner ear's structure.

Page 59: Clinical View: Otitis Media

Infection Overview

• Discusses otitis media, its causes, symptoms, and implications for child health.

Page 60: Hearing 1

Cochlear Structure

• Describes the structure and function of the cochlea and associated components.

Page 61: Hearing 2

Spiral Organ Functionality

• Outlines the structure and function of the spiral organ (Organ of Corti) involved in hearing.

Page 62: Sectioned Cochlea

• Visual representation showing a sectioned view of the cochlea.

Page 63: Close-Up of Cochlea

• Detailed visual showcasing specific structures within the cochlea.

Page 64: Hearing 3

Sound Pathway to Nerve Signal

• Details the pathway from sound waves entering the ear to the generation of nerve signals.

Page 65: Hearing 4

Hair Cell Stimulation

• Explains how hair cells in the cochlea respond to sound and result in neurotransmitter release.

Page 66: Hearing 5

Sound Perception

• Discusses the physics of sound perception, including factors affecting pitch and loudness.

Page 67: Sound Wave Detection

• Visual representation of sound wave detection mechanisms at the basilar membrane.

Page 68: Hearing 6

Loudness Perception

• Describes how loudness is perceived and measured, emphasizing the relation of wave amplitude to auditory perception.

Page 69: Clinical View: Cochlear Implants

Cochlear Implant Overview

• Discusses cochlear implants and their components, detailing their use and the sound perception they offer.

Page 70: Auditory Pathways

Auditory Pathways Overview

• Pathway from sound detection to perception in the cortex, including neural connections and reflexive functions.

Page 71: Clinical View: Deafness

Types of Deafness

• Differentiates between conductive and sensorineural deafness, explaining their causes and characteristics.