Human Body Sensory Systems Flashcards

Learn about important definitions, key terms, working, and many more things related to the Sensory Systems of the body with these image-based flashcards quizzes. learn, revise, and attempt the important questions, theory, and mechanisms of Sensory Systems in the body with these flashcards quizzes. ​

24 cards   |   Total Attempts: 190
  

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Cards In This Set

Front Back
Neurons
Answer 1
  • Afferent neurons - Sensory neurons that carry nerve impulses from sensory stimuli towards the central nervous system (CNS) & brain
  • Efferent neurons - Motor neurons that carry neural impulses away from the CNS & towards muscles to cause movement
  • (1) Sensory receptor --> (2) Sensory (afferent) neuron --> (3) Interneuron --> (4) Motor (efferent) neuron --> (5) Effector organ
Sensory Receptors (1)
  • Specialized neurons or nerve endings that respond to changes in the environment by converting energy from a specific stimulus into an action potential (AP) (a process known as transduction)
  • Sensory nerve endings that respond to stimuli by developing APs
Types of Senses
Answer 3
Sensory Receptor Cells --> Type of Energy Reception --> Sense Organ
  • Vision --> Photoreception: Detection of light, perceived as sight --> Eyes
  • Hearing --> Mechanoreception: Detection of vibration, perceived as hearing --> Ears
  • Touch --> Mechanoreception: Detection of pressure, perceived as touch --> Skin
  • Smell --> Chemoreception: Detection of chemical stimuli, perceived as smell --> Nose
  • Taste --> Chemoreception: Detection of chemical stimuli, perceived as taste --> Tongue
Sensory Receptors (2)
Answer 4
  • Range from single cells to complex sense organs
  • Types of receptors
    • Chemoreceptors - Chemicals (smell & taste)
    • Mechanoreceptors - Pressure & movement (touch, hearing, balance, blood pressure)
    • Photoreceptors - Light (vision)
    • Electroreceptors - Electrical fields
    • Magnetoreceptors - Magnetic fields
    • Thermoreceptors - Temperature
Sensory Receptors (3)
Answer 5
Sense --> Stimulus --> Sense Organ --> Receptor --> Sensation
  • Sight --> Light waves --> Eye --> Rods & cones of retina --> Colors, patterns, textures, motion, depth in space
  • Hearing --> Sound waves --> Ear --> Hair cells located in inner ear --> Noises, tones
  • Skin sensations --> External contact --> Skin --> Nerve endings in skin --> Touch, pain, warmth, cold
  • Smell --> Volatile substances --> Nose --> Hair cells of olfactory membrane --> Odors (musky, flowery, burnt, minty)
  • Taste --> Soluble substances --> Tongue --> Taste buds of tongue --> Flavors (sweet, sour, salty, bitter)
  • Vestibular sense --> Mechanical & gravitational forces --> Inner ear --> Hair cells of semicircular canals & vestibule --> Spatial movement, gravitational pull
  • Kinesthesis --> Body movement --> Muscles, tendons --> Nerve fibers in muscles, tendons, & joints --> Movement & position of body parts
Classification of Sensory Receptors
Answer 6
  • Based on stimulus location:
    • Telereceptors - Detect distant stimuli (i.e., vision & hearing)
    • Exteroceptors - Detect stimuli on the outside of the body (i.e., pressure & temperature)
    • Interoceptors - Detect stimuli inside the body (i.e., blood pressure & blood oxygen)
Sensory Receptors (4)
  • All receptors transduce incoming stimuli into changes in membrane potential
    • Receptor protein detects stimulus
    • Opening or closing of ion channel
    • Change in membrane potential
    • Signal sent to integrating center (central nervous system)
Question 8
Sensory Signal Transduction Pathways
Answer 8
  • Ionotropic sensory receptors
    • Mechanoreceptor: Pressure opens an ion channel
    • Thermoreceptor: Temperature influences a membrane protein that is a cation channel or is closely associated w/ the channel
    • Electroreceptor: An electric charge opens an ion channel
  • Metabotropic sensory receptors
    • Chemoreceptor: A molecule binds to a receptor, initiating a signal that controls the ion channel via second messenger cascade
    • Photoreceptor: Light alters a receptor protein, initiating a signaling cascade that controls an ion channel
Receptor Types
Answer 9
ALL --> INTRACELLULAR EFFECTS
  1. Ligand-gated ion channels (LIC, LGIC) (ex. cholinergic nicotinic receptors) --> Changes in membrane potential or ionic concentration within cell
  2. G protein-coupled receptors (GPCR) (ex. α & β adrenoceptors) --> Protein phosphorylation
  3. Enzyme-linked receptors (ex. insulin receptors) --> Protein & receptor phosphorylation
  4. Intracellular receptors (ex. steroid receptors) --> Protein phosphorylation & altered gene expression
Stimulus Encoding
  • All stimuli are ultimately converted into action potentials (APs) in afferent (sensory) neurons
  • Sensory receptors & sensory neurons must encode 4 types of information
    • Stimulus modality - The category of sensory input that a sensory system detects
    • Stimulus location - The ability to precisely localize a stimulus
      • Receptive field size - The smaller the receptive field, the better the acuity
      • Receptor density - The more receptors/receptive field, the better the acuity
    • Stimulus intensity
      • Threshold: The minimum intensity of a stimulus that is required to produce a response from a sensory system
      • Saturation: The maximum intensity of a stimulus that produces a response from a sensory system
      • Dynamic Range: The range of intensities that will produce a response from a receptor or sensory system (i.e., the difference between threshold & saturation)
    • Stimulus duration - The length of a time a stimulus must be applied for the resulting nerve impulse to produce excitation in the receptor. More intense stimuli require shorter excitation times to effect a cellular response. Any stimulus that acts too briefly to overcome the threshold intensity of the receptor will not elicit a response
Chemoreception
  • Most cells can sense chemical stimuli
  • Animals have many types of chemoreceptors
    • Olfaction (smell) - Detection of chemicals in the air
      • Pheromones - A chemical substance produced & released into the environment by an animal, especially a mammal or an insect, affecting the behavior or physiology of others of its species
    • Gustation (taste) - Detection of chemicals emitted from food
The Vertebrate Olfactory System
  • Can distinguish between thousands of odorants
  • Located in the roof of the nasal cavity
  • Mucus layer to moisten olfactory epithelium
  • Odorant binding proteins
    • Allow lipophilic odorants to dissolve in mucus
  • Odorant receptor is linked to G-protein
    • Odorant binding causes formation of cAMP
    • Opening of ion channels
    • Depolarization
The Gustatory System
  • 5 classes of tastants
    • Salty
    • Sweet
    • Bitter
    • Sour
    • Umami (savory or meaty) - Japanese belief that there is a 5th taste sense that triggers our need for protein (shiitake mushrooms & asparagus)
  • Sweet, umami, & salty indicate carbohydrates, proteins, & ions
  • Bitter & sour indicate potentially toxic substances
Taste Buds in Vertebrates
  • Taste receptors are epithelial cells that release neurotransmitter
    • Vertebrate taste receptors are not neurons
  • Taste receptor cells clustered in groups
    • On tongue, soft palate, larynx, & esophagus
  • A species' taste sensitivity depends on how many taste buds it has
  • Animals use taste to determine if food is safe to eat. Herbivores have so many taste buds b/c they need to be able to tell if a specific plant contains dangerous toxins
Mechanoreceptors
  • Transform mechanical stimuli (touch or sound) into electrical signals
  • All organisms (& most cells) sense & respond to mechanical stimuli