Gustatory and Olfactory System Histology (Dr. Cole) TEST 2 Flashcards
(38 cards)
1
Q
Gross Anatomy of Tongue
A
- The ANTERIOR Two Thirds of the Tongue consist of a Core of Mass of Skeletal Muscle oriented in THREE DIRECTIONS:
1) Longitudinal
2) Transverse
3) Oblique - The POSTERIOR One Third displays aggregations of Lymphatic Tissue, the LINGUAL TONSIL
2
Q
Development of the Tongue
A
- Anterior Tongue: 1st and 2nd Branchial Arches
- Posterior Tongue: 3rd and 4th Branchial Arches
3
Q
Dorsal Surface of the Tongue
A
- The DORSAL SURFACE of the Tongue is covered by NONKERATINIZED STRATIFIED SQUAMOUS Epithelium supported by a LAMINA PROPRIA associated with the Muscle Core of the Tongue
4
Q
Glands and the Muscles of the Tongue
A
Muscle Bundles:
1) Superior Longitudinal
2) Inferior Longitudinal
3) Transversus Linguae
4) Verticals Linguae
**SEROUS and MUCOUS Glands extend across the Lamina Propria and the Muscle. Their ducts OPEN into the CRYPTS and FURROWS of the Lingual Tonsils and CIRCUMVALLATE PAPILLAE
5
Q
Lingual Papillae
A
- The DORSAL SURFACE of the Tongue contains numerous Mucosal Projections called LINGUAL PAPILLAE
- Each Lingual Papilla is formed by a HIGHLY VASCULAR Connective Tissue Core and a Covering layer of STRATIFIED SQUAMOUS EPITHELIUM
6
Q
Lingual Papillae Cont.
A
- According to their shape, LINGUAL PAPILLAE can be divided into Four Types:
1) FILIFORM Papillae (Narrow Conical), which are the MOST ABUNDANT!!!!!!!!!
2) FUNGIFORM Papillae (Mushroom-shaped)
3) CIRCUMVALLATE Papillae
4) FOLIATE Papillae (Leaf-shaped), rudimentary in Humans
7
Q
Geographic Tongue
A
- Though to be an ORAL MANIFESTATION of PSORIASIS, a Dermatological Condition which causes patches of Dry, Flakey, Itchy skin
- The Classic manifestation of Geographic Tongue is an area of Erythema, with ATROPY of the FILIFORM PAPULLAE of the Tongue, surrounded by a SERPIGINOUS, White, Hyperkaratotic Border
8
Q
Fungiform Papillae
A
- NON KERATINIZED STRATIFIED SQUAMOUS
- Has around 5 TASTE BUDS along the APICAL SURFACE!!!!
9
Q
Serous Glands
A
- Serous Glands, or EBNER’s GLANDS, in the Connective Tissue, in contact with the UNDERLYING Muscle, are associated with the FOLIATE and CIRCUMVALLATE PAPILLA
- The Ducts of EBNER’S GLANDS open into the Floor of the Circular Furrows
- Glands secrete LINGUAL LIPASE and VEGP!!!!!!!
- VON EBNER’S GLAND PROTEIN (VEGP) undertakes the SELECTIVE BINDING of SAPID (Flavorful) Chemicals and their transport to Taste Receptors
10
Q
Foliate Papillae
A
- STRATIFIED SQUAMOUS Epithelium
- Ducts of SEROUS GLANDS (Von Exner’s Glands)
- Skeletal Muscle (Intrinsic and Extrinsic Tongue Muscles) are Deep to the papillae
LATERAL SURFACE of the FOLIATE PAPILLAE:!!!!!!!!!!!!!!
- Taste Buds
- Taste Pores
**Foliate Papillae are in PARALLEL ROWS, and the Taste Buds are in the LATERAL WALL
11
Q
Circumvallate Papillae
A
- Circumvallate (Wall-like) Papilale are located in the POSTERIOR PART of the TONGUE, aligned in front go the SULCUS TERMINALS.
- The Circumvallate Papilla occupies a RECESS in the Mucosa and therefore, it is surrounded by a CIRCULAR FURROW or TRENCH!!!!
- Contain HUNDREDS OF TASTE BUDS in their LATERAL WALLS
12
Q
Taste Buds
A
- The sides of the Circumvallate Papilla and the Facing Wall of Furrow contains SEVERAL TASTE BUDS
- Each Taste Bud, depending on the species, consists of 50 to 150 Cells, with its Narrow Apical Ends extending into a Taste Pore
- A Taste Bud has three cells components:
1) Taste Receptor
2) Supporting Cells (Immature Taste Cells)
3) Precursor Cell (Basal Cells)
13
Q
Ducts of Serous Glands (Von Exner’s)
A
- Ducts of Serous Glands EMPTY into MOAT
- Secretions flush area and Suspend TASTING PARTICLES
- Produce Von Ebner Land (VEG Protein (VEGP, Ebneren) that binds to Taste-producing Molecules. Concentrate and Transport
14
Q
Taste Buds Cont
A
- OVOID Chemoreceptors found:
1) In Papillae
2) On the SOFT PALATE
3) On POSTERIOR PHARYNX
4) EPIGLOTTIS
15
Q
Taste Receptors
A
- Taste Receptor Cells have a Life Span of 10 to 14 days.
- precursor Cells five rise to SUPPORTING CELLS (or Immature Taste Cells) which, in turn, become Mature Taste Receptor Cells.
- The BASAL PORTION of a Taste Receptor Cell makes contact with an AFFERENT Nerve Terminal derived from NEURONS in the Sensory Ganglia of the FACIAL, GLOSSOPHARYNGEAL, and VAGUS NERVES
16
Q
Taste
A
- Taste in INITIATED when Soluble Chemicals, called TASTANTS, diffuse through the Taste Pore and INTERACT with the G-PROTIEN Alpha, Beta, and Gamma Subunits (called GUSTDUCIN) linked to the Taste Receptors (Designated TR1 and TR2), present in the APICAL MICROVILLI of the Taste Receptor Cells
- GUANOSINE TRIPHOSPHATE (GTP) binding to the Alpha Subunit of the G-PROTEIN COMPLEX activates Target Molecules (Ion Channels in the Taste Receptor Cells)
- IONIC CHANGES within Taste Cells cause either DEPOLARIZATION or HYPERPOLARIZATION of the Receptor Cells
- An INCREASE in Intracellular Ca+ triggers the release of Neurotransmitters at the AFFERENT Synapse with the Afferent Nerve Terminal
- Some taste Receptors Cells respond to only ONE of the Basic Taste Substances. Others are Sensitive to MORE THAN ONE Taste Substance
17
Q
Taste Buds
A
- Nerve fibers innervate Type I - III
- All three probably funciotn in the Discrimination of Taste
- About 50 fibers Innervate a SINGLE Taste Bud
18
Q
Taste Sensations
A
- Sweet, Sour, Bitter, and Salty are the FOUR CLASSIC Taste Sensations
- A Fifth Taste is UMAMI (The taste of MONOSODIUM GLUTAMATE)
- A Specific Taste sensation is generated by SPECIFIC Taste Receptor Cells
- The FACIAL NERVE carries the FIVE TASTE Sensations; the GLOSSOPHARYNGEAL Nerve carries SWEET and BITTER Sensations!!!!
19
Q
Taste Perception
A
1) SWEET Stimuli: TIP of the Tongue (Sugars)
2) SALTY Stimuli: Sodium, POSTERIOR and LATERAL to the Tip of the Tongue
3) SOUR: On ANTERIOR 2/3 of DORSUM and along the LATERAL MARGIN (Acidic, H+)
20
Q
Bitter Tastants
A
- Varied Compounds with NO COMMON Molecular Structure
- Ex: Caffeine, Morphine and Nicotine
21
Q
Genetic Control of Taste
A
- KOHLRABI cotnains GLUCOSINOLATES, compound that INHIBIT Iodine uptake by the Thyroid
- Individuals with the SENSITIVE FORM of hTAS2R38 Taste Receptor Gene rate KOHLRABI as being MORE BITTER than people with the Less Sensitive form of the Gene
- Depending on the VERSION of the Gene, there are DIFFERENT SENSITIVITIES
22
Q
Umami
A
- Linked to a Specialized receptor for L-GLUTAMATE and other Amino Acids
- The distribution go Umami receptors is UNKNOWN
- GLUTAMATE is found Naturally in Meats, Cheeses, and Several Vegetables. GLUTAMATE Signals presence of Proteins and causes the INTAKE of PROTEINIOUS FOODS
- Often added to Processed Food as MONOSODIUM GLUTAMATE (MSG) which is used as a Flavor Enhancer
- Add Glutamate Taste to Promote Food Consumption (Elderly and Ill at RISK for Malnutrition)
23
Q
Taste Perception
A
- Each Tatse bud can discern all FIVE Tastes but appear to CONCENTRATE on TWO of the Five
- Taste Buds on the PALATE register primarily BITTER and SOUR
- POSTEIROR PHAYRN and EPIGLOTTIC register ALL FIVE Modalities
- The most likely Model suggest that Receptor Cells are TUNE to RESPOND to SINGLE TASTE MODALITIES - Sweet, Bitter, Sour, Salty, or Umami - and are INNERVATED by Individually tuned Nerve Fibers. IN this case, each taste quality is specified by the activity of NON-OVERLAPPING Cells and FIbers
24
Q
New Taste Modalities
A
- Protein (CD36) Receptor that specifically responds to the FLAVOR of FAT!!!!!
25
Fat (CD36)
- The receptor recognizes the TEXTURE of FAT
- Also functions to facilitate the UPTAKE of FATTY ACIDS (Mice Release Fat- Digesting Enzymes and INCREASES Intestinal Fat)
- May also possibly Increase the preference for Fatty Foods!!!!!
- Altered CD 36 protein, DECREASES (In Mice) the DESIRE for FATTY FOODS
26
Innervation of the Tongue
- Muscles of the Tongue DEVELOP from the Mesoderm of the OCCIPITAL MYOTOMES that Migrate into the DEVELOPING TONGUE, they are Innervated by the HYPOGLOSSAL NERVE (CN XII)
ANTEIROR 2/3 of Tongue:
Origin:
- Median Tongue Bud
- Lateral Lingual Swellings
Sensory Innervation:
- LINGUAL NERVE, Brach of Trigeminal Nerve, CN V
Innervation of Taste Buds (SVA):
- FACIAL NERVE, CN VII
POSTEIOR 1/3 of Tongue:
Origin:
- Hypopharyngeal Eminence!!!!!
Sensory Innervation:
- Glossopharyngeal Nerve, CV IX
Innervation of Taste Buds (SVA):
- Glossopharyngeal Nerve, CN IX
- Vagus Nerve, CN X, Near the BASE of the Tongue
27
Taste Sensory Information
- Most Sensory information that is thought of as Taste is actually OLFACTORY SENSATION subserved by the Olfactory Mucosa
28
Nasal Cavity
- Lined by PSEUDOSTRATIFIED COLUMNAR Epithelium with GOBLET CELLS!!!!
- Lamina Propria contains BOTH Serous and Mucous Glands to MOISTEN inspired Air and Trap particulate Contaminants
- Contains MAST and PLASMA CELLS (IgA, IgE, and IgG)
- Lamina Propria also contains EXTENSIVE VASCULAR PLEXUS (Swell or Cavernous Bodies)
29
Functions of Nasal Mucosa
1) AIR HYDRATION
- Secretions of Serous and Mucous Exocrine Glands and GLOBLET Cells MOISTEN the Surface of the Nasal Cavity
- ADD Water Vapor to Inspired Air
2) AIR FILTRATION
- Conchae interrupt Air Flow and Create Turbulence
- Particulate MATTER thrown against Conchae and ADHERES to its Moist Surface
- Cilia move Mucus/ Matter into NASOPHARYNX
3) TMEPERATURE REGULATION
- Superficial Vascular Plexus (Swell Bodies) within Lamina Propria
- Can Warm or Cool Inspired Air
30
Olfactory Epithelium
- PSEUDOSTRATIDIED COLUMNAR Epithelium
- Restricted to ROOF of NASAL CAVITY, Upper Surface of SUPERIOR CONCHAE
- Contains Three Cell Types:
1) Olfactory Cells
2) Supporting Cells (SUSTENTACULAR)
3) Basal Cells
- Underlying Lamina Propria also contains LYMPHOID Cells
31
Olfactory Cells
- Bipolar Sensory Neurons that span the THICKNESS of the Epithelium
- Dendrite EXTENDS to FREE Surface and DILATES to form the OLFACTORY VESICLE
- Projects, along with Cilia, ABOVE the Epithelial Surface
- PROXIMAL Process extends Basally, becomes a NON-MYELINATED AXON, and forms BUNDLES of NERVE FIBERS, the FILA OLFACTORIA!!!!!!!!!!!!
32
Supporting Cells of Nasal Cavity
- SUSTENTACULAR CELLS
- COLUMNAR CELLS with OVAL Nuclei (Apical One-Third of the Cell)
- Apical Surface has Microvilli submerged in SEROMUCOUS Fluid Layer
- Contain light yellow Pigment that gives Olfactory Epithelium its Color
- Provide PHYSICAL SUPPORT, NOURISHMENT, and ELECTRICAL INSULATION for the Olfactory Cells
33
Basal Cells of the Nasal Cavity
- The BASAL CELLS are Mitotically ACTIVE STEM CELLS, producing Daughter Cells that differentiate FIRST into Immature Olfactory Cells and then into Mature Olfactory Cells.
- Olfactory Cells PROLIFERATE during Adult Life
- The Life Span of an Olfactory Cell is about 30 to 60 Days!!!!
34
Olfaction
- CILIA Contains the Odorant Receptor (OR. There are about 100 Genes expressing ORs, but each Olfactory Receptor expresses only ONE OR Gene
- Olfactory Serous Glands (GLANDS OF BOWMAN) secrete SEROUS FLUIDS in which ODIFEROUS SUBSTANCES are DISSOLVED
- The Secretory Fluid contains the Odorant-Binding Protein (OBP) with HIGH BINDING AFFINITY for a Large Number of ODORANT Molecules
- OBP carries Odorants to Receptors present on the Surface of the Modified CILIA and removes them after they have been sensed
- The Secretory Protective Product of the Glands of BOWMAN contains Protective Substances such as Lysozyme and Immunoglobulin A (IgA) secreted by PLASMA CELLS
35
Olfaction
- Axons from OLFACTORY CELLS with the same OR terminate in One to Three Glomeruli present in the Olfactory Bulb
- Dendritic ending son Predominantly MITRAL CELLS extend into the GLOMERULI!!!!!! Axons of Mitral Cells form the OLFACTORY TRACT!!!!!!!
- Olfactory Receptor Cells have a Life Span of 30 to 60 days and can REGENERATE from BASAL CELLS
- Temporary or Permanent damage to the Olfactory Epithelium causes ANSOMIA (
36
Kallman Syndrome
- an X linked disease characterized by ANOSMIA (No sense of Smell), SMALL GENITALIA and STERILE GONADS
1) ANOSMIA: Lack of Neurons in the Brian (MITRAL CELLS) that receive Input from Olfactory Neurons (Olfactory Bulb DOES NOT Develop)
2) SMALL Genitalia/ Sterility: LACK of GONADOTROPIN RELEASING HORMONE (GnRH), secreted by the Hypothalamus
3) GnRH required for Secretion of Luteinizing Hormone (LH), required for Gonadal Development and Genital Maturation
37
Kallman Syndrome Cont 1
- GnRH- Secreting Neurons dont originate in the Hypothalamus
- Originate in Olfactory Epithelium (VOMERONASAL Organ) and Migrate into the Brian
- Axons of Olfactory Neurons must contact DEVELOPING Brain to stimulate Olfactory Bulb Development
38
Kallman Syndrome Cont 2
- FAILURE of GnRH-Secreting Neuron and Olfactory Neuron GRWOTH Cones to MIGRATE into the Brain
- Defect gene, KAL-1, codes for ANOSMIN-1, a Cell Adhesion Protein that is expressed in the Olfactory System and Medial Walls of Primitive Cerebral Hemispheres
