Chapter 18
Olfactory Discrimination
-Can make subtle distinctions between thousands of chemical stimuli -They are the best, if not the only known example of neuronal regeneration -Despite ongoing replacement, as age progresses, the number of olfactory receptors decline, thus reducing one's ability to smell, which contribute to lack of appetite.
Conjunctiva
-Delicate membrane lining (stratified squamous epithelia) that covers the inner surface of the lids and anterior surface of the eye to the edges of the cornea -Lubricates and protects the eye
MEMBRANOUS LABYRINTH
-Filled with Endolymph fluid -Surrounded by Perilymph inside Bony Labyrinth -Divides into 2 subdivisions 1.) Cochlear Duct (hearing) 2.)Vestibular Complex
Temperature Receptors (Thermoreceptors)
-Found in the dermis of the skin, skeletal muscles, in the liver, and in the hypothalamus. -Free nerve endings -Known structural differences between cold and warm thermoreceptors
Gustation
-Located on the dorsal side of the tongue and adjacent portions of the pharynx and larynx
Phasic (Fast Adapting)
-Normally inactive sensory neurons, but become active for a short period whenever there is a change in the conditions they are monitoring. -They provide information on the intensity and the rate of change of a stimulus.
Lacrimal Apparatus
-Produces, distributes, and removes tears -Locate: lacrimal gland, lacrimal gland ducts, lacrimal punctum, superior and inferior lacrimal canacliculus, lacrimal sac and nonlacromal duct
Inner Ear
-Responsible for our senses of equilibrium and hearing -Receptors are housed within a collection of fluid-filled tubes known as MEMBRANOUS LABYRINTH
Tonic (Slow Adapting) Receptors
-Sensory neurons that are always active -Ex: photoreceptors of the eye -Always sending signals to the CNS
Chemoreceptors
-Specialized neurons that can detect small changes in the concentration of specific chemicals or compounds -Locations (3): 1.) Respiratory Centers & Medulla Oblongata (changes in pH and P (CO2) in cerebrospinal fluid 2.) Carotid Bodies (changes in pH, P (CO2), and P(O2) in blood 3.) Aortic Bodies: (changes in pH, P (CO20 and P(O2) in blood
Barororeceptors
-Stretch receptors that monitor changes in the stretch of walls of an organ, and therefore the pressure within that organ. -Locations (5); 1.) Digestive Tract 2.) Bladder Wall 3.) Colon 4.) Lung 5.) Carotid Sinus and Aortic Sinus
Gustatory Receptors
-Taste receptors are clustered within individual taste buds -Each taste bud contains around 40 slender receptors called Gustatory Cells -Taste hairs (microvilli) cover the Taste Pore
Auditory Ossicles
-Tiny ear bones (smallest bones in the body) -Connect the tympanic membrane with the receptor complex of the inner ear 1.) Malleus 2.) Incus 3.) Stapes
General Sense Receptors (4)
1.) Nociceptors: respond to a variety of stimuli usually associated with tissue damage 2.) Thermoreceptors: respond to change in temperature 3.) Mechanoreceptors: stimulated/inhibited by physical distortion, contact, or pressure on their plasmalemmae 4.) Chemoreceptors: monitor chemical composition of body fluids and respond to the presence of specific molecules
Mechanoreceptors (Don't have to memorize)
1.) Tactile: touch, pressure, and vibration 2.) Baroreceptors: detect pressure changes in the walls of blood vessels and portions of the digestive, reproductive, and urinary tracts 3.) Proprioceptors: monitor the positions of the joints and muscles and are the most complex of the general sensory receptors
2 Additional Tastes
1.) Umami: pleasant taste that is characteristic of chicken/beef broth 2.) Water
Three Types of Papillae
All on the human tongue. 1.) Filiform 2.) Fungiform 3.) Circumvallate
Semicircular Canals and Ducts
Be able to identify: bony labyrinth, all 3 semicircular ducts, vestibule, cochlea, cochlear duct, endolymph and perilymph
Vestibular Complex
Divides into: 1.) Semicircular ducts (rotation) 2.) Utricle and Saccule (gravity and linear acceleration) See pg. 481 figure 18.11
Receptor Specificity
Each receptor has a characteristic sensitivity. For example, a touch receptor is very sensitive to pressure but relatively insensitive to chemical stimuli.
Know all the parts of the eye
Focus on the main anatomical components & the basic functions of these (pg. 494)
Gustatory Discrimination
Four Primary Taste Sensations: 1.) Sweet 2.) Salty 3.) Sour 4.) Bitter
Central Adaption
Process: a few seconds after exposure to a new smell, conscious awareness of the stimulus virtually disappears, although the sensory neurons are still quite active.
Slow, Fast and Referred Pain (Nociceptors)
Slow: burning, aching pain, result from the same types of injuries as fast pain sensations (deep cuts, or similar injuries). Fast: pricking pain, deep cuts, or similar injuries. Referred Pain: pain felt at a particular site, but originates from another location
Papillae
Taste buds lie along the sides of the epithelial projections called PAPILLAE.
Interpretation of Sensory Information: Label Line
The connection between receptor and cortical neuron is called a LABLED LINE.
Free Nerve Endings
The simplest receptors are the dendrites of sensory neurons. They can be stimulated by many different stimuli. For example, the free nerve endings that provide the sensation of pain may be responding to chemical stimulation, pressure, temperature changes, or physical damage.