slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
LESSON # 23 PowerPoint Presentation
Download Presentation
LESSON # 23

Loading in 2 Seconds...

play fullscreen
1 / 21

LESSON # 23 - PowerPoint PPT Presentation


  • 142 Views
  • Uploaded on

LESSON # 23. Special Senses: 1- Olfaction (smell) 2- Gustation (taste) 3- Vision 4- Equilibrium and Hearing. Special Senses: . 1- Olfaction (smell) . 3- Vision. 2- Gustation (taste). 4- Equilibrium and Hearing. 1- Olfaction (smell).

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'LESSON # 23' - shirin


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

LESSON # 23

  • Special Senses:
    • 1- Olfaction (smell)
    • 2- Gustation (taste)
    • 3- Vision
    • 4- Equilibrium and Hearing
slide2

Special Senses:

  • 1- Olfaction (smell)
  • 3- Vision
  • 2- Gustation (taste)
  • 4- Equilibrium and Hearing

1- Olfaction(smell)

It is provided by paired olfactory organs, which are located in the nasal cavity on either side of the nasal septum.

Olfactory bulb

Olfactory tract

Olfactory nerve fibers

Cribriform plate of ethmoid

Olfactory organ:

Olfactory epithelium

Lamina propria

slide3

Olfactory (Bowman) gland

Their secretions absorb water and form a thick pigmented mucus.

Lamina propria

It consists of areolar connective tissue with blood vessels and nerves.

Olfactory epithelium:

1- Regenerative basal cells

They divide to replace worn out olfactory receptors cells.

2- Olfactory receptors cells

They are highly modified neurons sensitive to odorants.

Knob

3- Supporting cells

They are enlargements that project beyond the epithelial surface and provide the base for up to 20 cilia.

Olfactory nerve fibers

They are epithelial cells

Odorants are small organic molecules. The strongest smells are associated with molecules of high solubility both in water and lipids.

Cilia

They contain receptors called odorant-binding proteins that match specific odorant particles. They can only be stimulated by water-soluble and lipid-soluble particles that can diffuse through the overlaying mucus. Depolarization is produced the G protein-second messenger mechanism.

slide4

Olfactory Pathways

  • Axons leaving the olfactory epithelium collect into 20 or more bundles and penetrate cribriform plate of ethmoid to reach the olfactory bulbs.

Olfactory bulb

Olfactory tract

  • The parallel distribution of smell information in the limbic system and hypothalamus explains the profound emotional and behavioral response, as well as memories, that can be triggered by certain smells.

Limbic system

Hypothalamus

Primary olfactory cortex

(temporal lobe)

  • Arriving information reaches information centers without first synapsing in thalamus (all other sensations are relayed from processing centers in the thalamus).
slide5

2- Gustation (taste)

Taste receptors (or gustatory receptors) are distributed on tongue and portions of pharynx, larynx, and epiglottis.

By the time we reach the adulthood, the taste receptors of the pharynx, larynx and epiglottis have decreased in importance and abundance.

1- Circumvallated papilla

They for a V near the posterior margin of the tongue.

They can contain as many as 100 taste buds.

2- Fungiform papilla

They are small and contain about five taste buds.

3- Filliform papilla

They provide friction that helps the tongue move objects around the mouth.

They do not contain taste buds.

slide6

Taste Receptors

They mature to become gustatory cells.

They divide to produce daughter cells that mature in stages.

Transitional cells

Basal cells

Taste pore

Taste hairs (microvilli)

Cranial nerves VII (facial), and IX (glossopharyngeal).

Dissolved chemicals bind to receptor proteins and produce depolarization of the cell by two mechanisms:

Dendrites of sensory neurons

Gustatory cells

1- Open chemically gated ion channels.

2- G protein-second messenger mechanism.

slide7

Gustatory Pathways

  • Cranial nerves that synapse within solitary nucleus of medulla oblongata, then on to thalamus and primary sensory cortex.
  • The result of taste receptor stimulation is the release of neurotransmitters by the receptors cells.
  • The dendrites of the sensory neurons are tightly wrapped by folds of the receptor plasma membrane, and neurotransmitter release generates an action potential in the afferent fibers.

A conscious perception of taste is produced as the information received from the taste buds is correlated with other sensory data:

1- Information about the texture of food.

Gustatory cortex (Insula)

2- Information about taste-related sensations such as “peppering” or “burning hot”.

3- Information about smell from olfactory receptors.

slide8

Lacrimal caruncle

Accessory Structures of the Eye

Lacrimal gland

Lateral cantus

Lacrimal sac

Medial cantus

Lower eyelid

Palpebral conjunctiva

Nasolacrimal duct

Opening of nasolacrimal duct

3- Vision

Lacrimal gland ducts

Superior and inferior lacrimal canaliculi

They carry the tears to the lacrimal sac.

It produces tears.

It collects tears and carries them to the nasolacrimal duct.

It drains excess of tears to the nasal cavity.

slide9

Extrinsic Muscles of the Eye

(eye looks up)

Superior rectus

Inferior oblique

Lateral rectus

Superior oblique

Trochlea

Medial rectus

Inferior rectus

(eye rolls, looks down & to the side)

(eye rotates medially)

(eye rotates laterally)

(eye rolls, looks up & to the side)

(eye looks down)

slide10

Innervation of the Extrinsic Muscles of the Eye

MUSCLE

ACTION

INNERVATION

SUPERIOR RECTUS

EYE LOOKS UP

OCULOMOTOR (III)

INFERIOR RECTUS

OCULOMOTOR (III)

EYE LOOKS DOWN

MEDIAL RECTUS

EYE ROTATES MEDIALLY

OCULOMOTOR (III)

LATERAL RECTUS

EYE ROTATES LATERALLY

ABDUCENS (VI)

EYE ROLLS, LOOKS DOWN & TO THE SIDE

SUPERIOR OBLIQUE

TROCHLEAR (IV)

EYE ROLLS, LOOKS UP & TO THE SIDE

INFERIOR OBLIQUE

OCULOMOTOR (III)

slide11

Innervation of the Extrinsic Muscles of the Eye

(eye looks up)

Superior rectus

Inferior oblique

Lateral rectus

Trochlea

Superior oblique

Medial rectus

Inferior rectus

Oculomotor (pair III)

(eye rolls, looks down & to the side)

Trochlear nerve (pair IV)

(eye rotates laterally)

(eye rotates medially)

Abducens nerve (pair VI)

Oculomotor (pair III)

(eye rolls, looks up & to the side)

Oculomotor (pair III)

Oculomotor (pair III)

(eye looks down)

slide12

Sclera or white of the eye (protects and gives shape to the eyes)

Choroid ( vascular layer the nourishes the retina)

Ciliary muscle (tension the suspensory ligaments)

Ciliary body

Ciliary process (produces the aqueous humor)

Neural part

Pigmented part

LAYERS OF THE EYE BALL

1- The fibrous tunic

Cornea (clear outer part) (It allows the light to come in)

2- The vascular tunic or uvea

Iris (pigmented areas and intrinsic muscles that controls the size of the pupil)

3- Neural tunic or retina

slide13

Layers and Chambers of the Eye Ball

Vascular tunic (uvea):

Fibrous tunic:

Fovea centralis

Posterior chamber

Optic disc

Pigmented part

Optic nerve

Neural part

Cornea

Sclera

Choroid

Ciliary body

Iris

Anterior cavity

Anterior chamber

Lens

Posterior cavity

Neural tunic (retina):

It contains only cones, which are responsible for the sharpest vision.

It is called also blind spot because contains no photoreceptors.

slide14

It allows the light to come in.

Pupil

Posterior cavity

Posterior chamber

It focuses the light in the retina.

Ciliary processes

Ciliary muscle

Lens

Cornea

Anterior chamber

It allows the light to come in.

Sclera

It contains vitreous humor, which maintains the shape of the lens & prevents collapse

Choroid

Iris

Anterior cavity

Ciliary Body:

It contains aqueous humor that nourishes the lens & the cornea because they do not have blood vessels.

It controls the size of the pupil.

Sclera venous sinus (canal of Schlemm)

It drains the aqueous humor. The obstruction raises the intraocular pressure and glaucoma results.

It nourishes the retina and absorbs excess of light.

It protects & gives the shape to the eyes

slide15

Pigmented part

Cones

Rods

Bipolar cells

Ganglion cells

Neural part

Amacrine cells

Horizontal cells

Histological Organization of the Retina

It absorbs light preventing visual echoes.

They provide color vision

Photoreceptors

They detect light in dim light and provide black and white vision.

Light

They connect the photo- receptors to the ganglion cells.

They are neurons whose axons forms the optic nerve. They carry visual information.

They adjust the sensitivity of the retina by either facilitating or inhibiting the communication between the photoreceptors and the ganglion cells.

slide16

4- Equilibrium and Hearing

Anatomy of the Ear

The special senses of equilibrium and hearing are provided by the ear.

External Ear

Middle Ear

Inner Ear

Pinna or auricle

Ossicles

Membranous labyrinth

Ear canal

Pharyngotympanic or auditory or eustachian tube

Bonny labyrinth

Ceruminous glands

Vestibule

Semicircular canals

Tympanic membrane

Cochlea

Internal Ear

External Ear

Middle Ear

slide17

The External Ear

It transmits the sound waves to the middle ear ossicles.

Pinna or auricle

It protects the opening of the canal and provides directional sensitivity.

Tympanic membrane

It focus and directs the sound waves into the tympanic membrane.

Ear canal

slide18

The Middle Ear

Tensor tympani muscle

It tenses the tympanic membrane reducing the amount of movement possible.

Malleus (hammer)

Stapes (stirrup)

Stapedius muscle

Its handle is attached to the tympanic membrane.

Its base is bound to the oval window.

It pulls the stapes, reducing movement of the stapes in the oval window.

Incus (anvil)

It equalizes the pressures on either side of the tympanic membrane.

Auditory tube

slide19

The Internal Ear

1- Linear acceleration (maculae in the vestibule).

Equilibrium:

2- Gravity (maculae in the vestibule).

Bony labyrinth

3- Rotational movement of head (cristae in the ampulla).

Membranous labyrinth

Hearing:

Organ of Corti in the cochlea.

Ampulla

Saccule

They contain the cristae (receptors for rotational movements of the head).

Utricle

Semicircular canals

Semicircular ducts

Endolymph

Perilymph

Bony labyrinth

Membranous labyrinth

Vestibule

Cochlea

They contain the maculae (receptors for sensations of gravity and linear acceleration).

It contains the organs of Corti (receptors for hearing).

slide20

1- Linear acceleration (maculae in the vestibule).

Equilibrium:

2- Gravity (maculae in the vestibule).

3- Rotational movement of head (cristae in the ampulla).

The basic receptor mechanism is the same for both senses: hair cells, which are mechanoreceptors.

Hearing:

Organ of Corti in the cochlea.