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Questions and Answers
Which of the following accurately describes the relationship between stimulus intensity and the frequency of action potentials generated by an afferent neuron?
Which of the following accurately describes the relationship between stimulus intensity and the frequency of action potentials generated by an afferent neuron?
Which of the following is NOT a characteristic of mechanoreceptors?
Which of the following is NOT a characteristic of mechanoreceptors?
Which type of sensory receptor is responsible for detecting changes in temperature?
Which type of sensory receptor is responsible for detecting changes in temperature?
What is the primary function of photoreceptors?
What is the primary function of photoreceptors?
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Which type of sensory receptor is responsible for detecting tissue damage and pain?
Which type of sensory receptor is responsible for detecting tissue damage and pain?
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Which of the following is NOT a way that the intensity and extent of a stimulus are encoded?
Which of the following is NOT a way that the intensity and extent of a stimulus are encoded?
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Which type of sensory receptor typically uses a specialized cell that synapses with an afferent neuron?
Which type of sensory receptor typically uses a specialized cell that synapses with an afferent neuron?
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Why are some mechanoreceptors considered enclosed nerve endings?
Why are some mechanoreceptors considered enclosed nerve endings?
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Which of the following best describes the role of neurotransmitters in sensory perception?
Which of the following best describes the role of neurotransmitters in sensory perception?
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How do chemoreceptors contribute to our sense of taste?
How do chemoreceptors contribute to our sense of taste?
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What is the role of the hair cells in the Organ of Corti?
What is the role of the hair cells in the Organ of Corti?
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Which of the following animals does not have outer ears?
Which of the following animals does not have outer ears?
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What type of visual information do the most complex eyes provide?
What type of visual information do the most complex eyes provide?
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What is retinal synthesized from?
What is retinal synthesized from?
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What is an ocellus?
What is an ocellus?
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Which type of mechanoreceptors are responsible for detecting touch and pressure stimuli in vertebrates?
Which type of mechanoreceptors are responsible for detecting touch and pressure stimuli in vertebrates?
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What role do proprioceptors play in the central nervous system?
What role do proprioceptors play in the central nervous system?
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Which structure in aquatic invertebrates is known to be a proprioceptor?
Which structure in aquatic invertebrates is known to be a proprioceptor?
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What do the halteres of crane flies transduce information about?
What do the halteres of crane flies transduce information about?
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What substance is contained in the lateral line system of fishes that responds to vibrations and currents?
What substance is contained in the lateral line system of fishes that responds to vibrations and currents?
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What is the role of hair cells in the vestibular apparatus?
What is the role of hair cells in the vestibular apparatus?
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Which components make up the vestibular apparatus in vertebrates?
Which components make up the vestibular apparatus in vertebrates?
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How do sound waves travel in water compared to air?
How do sound waves travel in water compared to air?
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Which structure in the ear is responsible for concentrating and focusing sound waves?
Which structure in the ear is responsible for concentrating and focusing sound waves?
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What is the primary function of the endolymph in the inner ear?
What is the primary function of the endolymph in the inner ear?
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What structures comprise the middle ear?
What structures comprise the middle ear?
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What initiates the auditory processing in the ear?
What initiates the auditory processing in the ear?
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Which statement about the organ of Corti is correct?
Which statement about the organ of Corti is correct?
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What is the primary function of sensory receptors in animal body systems?
What is the primary function of sensory receptors in animal body systems?
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Which of the following statements accurately describes sensory transduction?
Which of the following statements accurately describes sensory transduction?
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What is the relationship between stimulus intensity and receptor potential?
What is the relationship between stimulus intensity and receptor potential?
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How do changes in membrane permeability contribute to receptor potential?
How do changes in membrane permeability contribute to receptor potential?
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What is the significance of the receptive field in sensory perception?
What is the significance of the receptive field in sensory perception?
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Why is the detection of environmental variables critical for homeostasis?
Why is the detection of environmental variables critical for homeostasis?
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What is the primary difference between afferent and efferent neurons?
What is the primary difference between afferent and efferent neurons?
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Which of the following best describes the role of specialized receptor cells in sensory perception?
Which of the following best describes the role of specialized receptor cells in sensory perception?
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Flashcards
Mechanoreceptors
Mechanoreceptors
Receptors that detect mechanical stimuli like touch and pressure.
Proprioceptors
Proprioceptors
Receptors that monitor body and limb positions.
Statocysts
Statocysts
Structures in invertebrates that detect orientation and balance.
Halteres
Halteres
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Lateral Line System
Lateral Line System
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Bending of Hair Cells
Bending of Hair Cells
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Vestibular Apparatus
Vestibular Apparatus
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Function of Endolymph
Function of Endolymph
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Semicircular Canals
Semicircular Canals
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Otoliths
Otoliths
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Components of the Ear
Components of the Ear
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Sound Wave Transmission
Sound Wave Transmission
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Role of the Cochlea
Role of the Cochlea
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Sensory Receptors
Sensory Receptors
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Sensory Transduction
Sensory Transduction
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Stimulus
Stimulus
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Receptor Potential
Receptor Potential
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Afferent Neurons
Afferent Neurons
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Photoreceptors
Photoreceptors
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Graded Potential
Graded Potential
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Hair cells in the Organ of Corti
Hair cells in the Organ of Corti
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Pinnae in animals
Pinnae in animals
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Retinal
Retinal
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Ocellus
Ocellus
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Synaptic Cleft
Synaptic Cleft
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Strength of Stimulus
Strength of Stimulus
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Free Nerve Endings
Free Nerve Endings
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Enclosed Nerve Endings
Enclosed Nerve Endings
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Thermoreceptors
Thermoreceptors
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Nocioreceptors
Nocioreceptors
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Chemoreceptors
Chemoreceptors
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Study Notes
Animal Body Systems: Sensory Systems
- Animals detect a wide range of environmental variables, which is crucial for homeostasis.
- Sensory input is converted into electrical signals via sensory receptors.
- Sensory receptors are formed by dendrites of afferent neurons or by specialized receptor cells. These act as transducers, converting sensory information into neural activity.
Sensory Transduction
- Sensory transduction is the process where stimuli cause changes in membrane potentials in sensory receptors.
- Stimuli can be light, heat, sound waves, mechanical stress, or chemicals.
- No receptor leads to no reaction, only the correct receptor can react.
Sensory Receptors
- Sensory receptors respond to stimuli in their receptive fields.
- The magnitude of the stimulus determines the change in the receptor potential; this is a graded potential.
- Changes in receptor potential are caused by variations in the rate of positive ion (Na+, K+, Ca2+) movement across the plasma membrane. This triggers synaptic release of neurotransmitters.
Strength of Stimuli
- Stimulus intensity and extent are encoded in multiple ways.
- Frequency of action potentials (number per unit time) in afferent neurons dictates stimulus intensity and frequency.
- The number of afferent neurons involved in response also indicate the strength of stimuli.
Structural Forms of Sensory Receptors
- Specialized cells synapse with afferent neurons, transmitting sensory information to the CNS.
- Peripheral endings of afferent neurons are involved in some sensory receptors.
Sensory Receptor: Free Nerve Endings
- A stimulus causes a change in membrane potential in free nerve endings, generating a nerve signal (action potential).
- Examples of free nerve endings include pain receptors and some mechanoreceptors.
Sensory Receptor: Enclosed Nerve Endings
- A stimulus affecting the specialized structure triggers an action potential in the afferent neuron.
- Examples include mechanoreceptors.
Sensory Cell That Consist of Two Separate Cells
- A synapse with an axon of an afferent neuron triggers a change in membrane potential leading to release of neurotransmitter.
- Neurotransmitter triggers an action potential in the axon of the afferent neuron.
- Examples include: photoreceptors, chemoreceptors, and some mechanoreceptors.
Major Categories of Sensory Receptors
- Mechanoreceptors: Respond to mechanical deformation (touch, pressure).
- Examples: auditory receptors in the ears; Temperature receptors in skin; skin & internal organs.
- Thermoreceptors: Respond to cold and heat.
- Nocioreceptors: Respond to pain (tissue damage).
- Electromagnetic Receptors: Respond to electrical and magnetic fields (light, infrared, ultraviolet).
- Photoreceptors: Respond to visible light. Examples include visual receptors in the retina, in the eye.
- Chemoreceptors: Respond to various chemicals. Examples include taste buds on the tongue.
Sensory Cell Membrane Proteins in Response to Stimuli
- Mechanosensors: Pressure changes open ion channels.
- Thermosensors: Temperature influences a membrane enzyme, controlling channels.
- Electrosensors: An electric charge opens an ion channel.
- Chemosensors: taste/smell molecules trigger a cascade to control ion channels.
- Photosensors: Light changes the membrane protein to control ion channels.
Mechanoreceptors: Touch and Pressure
- Detect mechanical stimuli (touch and pressure).
- Incorporated into surface tissues, skeletal muscles, blood vessels, and internal organs.
- Four types of mechanoreceptors detect tactile stimulation in human skin.
Mechanoreceptors: Proprioceptors
- Detect stimuli used to monitor and maintain body and limb positions.
- Example: statocysts in aquatic invertebrates, hair cells that generate AP when the hair are moved.
- Mechanoreceptors in muscles, tendons, and joints detect changes in the pressure/tension of body parts.
Two More Examples of Proprioceptors
- Halteres in crane flies, used for pitch, roll, and yaw during flight.
- The lateral line system of fishes, contains neuroblasts, gelatinous cupula pushed and pulled by vibrations, bending hair cells.
Vertebrate Vestibular Apparatus: Balance and Orientation
- Used for balance, orientation, and detecting head and body movements. Essential for maintaining equilibrium.
- Filled with fluid (endolymph).
- Consists of 3 semicircular canals and 2 chambers (utricle and saccule).
Human Vestibular Apparatus
- Contains sensory hair cells that bend according to head movement.
- Receptor in utricle or saccule respond to accelerating head movement, which lags behind, due to inertia, from the acceleration.
Detection of Sound
- Sound waves are produced by alternating compression and decompression of air or water.
- Water transmits sound faster than air.
- Invertebrates have mechanoreceptors in their skin.
- Vertebrates use auditory structures to convert vibrations to sensory hair cell action potentials.
Terrestrial Vertebrate Ear
- Sound waves enter the auditory canal, strike the tympanic membrane and vibrate.
- Vibrations move through one or more bones, to the fluid-filled inner ear.
Structures of the Human Ear
- Vibrations are transmitted through the oval window of the inner ear, transmitting into the fluid and triggering a response in hair cells.
- Hair cells in the organ of Corti are the key components in transmitting data to the brain via sensory nerves.
Some Animals Have Pinnae; Some Don't
- Different species have different structures for sound detection.
- Examples include: whales, reptiles, birds, and bats.
Photoreceptors
- Detect light at particular wavelengths which depend on the specific photoreceptor.
- Convert light stimuli to action potentials sent to the visual centers in the CNS.
- Different animals contain different retinal forms (light-absorbing pigments).
- Simpler eyes distinguish light from dark; more complex eyes distinguish forms and colors.
Invertebrate Eyes Take Many Forms
- Ocelli are the simplest form of eyes, having no lens.
- Many invertebrates contain photoreceptors in their skin.
- Planarians, insects, arthropods, and molluscs have photoreceptor cells forming a cup- and/or pit-like shape.
Compound Eyes
- Compound eyes use ommatidia (faceted visual units) to perceive light.
- Cornea and crystalline cone focus light onto photoreceptors.
- Microvilli containing rhodopsin absorb light triggering an action potential.
- The resulting image is a motion sensitive mosaic image.
Single-Lens Eyes
- Like a camera, operate on the principle of focusing light using the cornea, lens and retina.
- Muscles in the iris adjust the pupil size, regulating light intake.
- Lens adjusts to focus images at different distances.
Accommodation, Focusing on a Distant Object
- Focusing involves changing the lens shape.
- Distant objects require a flatter lens, accomplished when ciliary muscles relax which tightens the ligaments.
- Near objects require a rounder lens, accomplished by contracting the ciliary muscles which loosens the ligaments.
Photoreceptors of the Retina
- Rods detect low-intensity light; Cones detect different wavelengths (colors).
- Rods and cones are linked to neurons in the retina that process visual information.
Converting Signals to Electrical Impulses
- Photoreceptors have outer (stacked discs), inner (metabolic activities), and synaptic (neurotransmitter storage) segments.
- Different animals utilize different retinal forms for light absorption.
Photoreceptors: Rhodopsin
- Rhodopsin, in rods, consists of opsin protein and retinal.
- Light causes retinal to change shape, triggering a cascade that creates an action potential.
Retina: Initial Integration
- Photoreceptors send signals to ganglion, horizontal, bipolar & amacrine cells.
- This is the first step in processing visual information within the retina.
Opsins and Color Vision
- Color vision relies on cones with different photopsin opsins (combined with retinal).
- Humans have three types of cones for color perception.
- Most mammals only have two types of cones.
Neural Pathways for Vision
- The optic nerve carries visual signals to the optic chiasm.
- Visual information is processed in the lateral geniculate nucleus and then transferred to the visual cortex for further processing.
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Description
Explore the fascinating world of sensory systems in animals. This quiz delves into how sensory receptors convert environmental stimuli into electrical signals, crucial for maintaining homeostasis. Test your understanding of sensory transduction and the various types of sensory receptors.