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.