ANPH 1000 - Unit 3

Where are mechanoreceptors found? (3)

1. connective tissue

2. sensitive, hairless areas on skin (ie. fingertips, lips, palm)

3. Subcutaneous tissue under skin & joints

Sensory receptor

Specialized cell that respond to specific type of stimuli

What information about the stimulus does sensory receptors tell you about? (3)

1. Type

2. Location

3. Intensity

Receptive field

Area monitored by 1 neuron

Sensory projection

Brain identifies where stimulus is from

Chemoreceptors

Odors, taste, chemicals

Mechanoreceptors

Change position of receptor

ie. pressure, stretch, vibration

Thermoreceptors

Change in temp

Nociceptors (Where, what, & type of stimuli)

• Pain receptors w/ free nerve endings

• Skin, mucous membranes, all organs except brain

• Damage from trauma, heat, chemicals, lack of O₂

Photoreceptors

• Rods - Black & white

• Cones - Color

Fast pain fibers

• Sharp, localized, stabbing pain at the time of injury

• Myelinated

Slow pain fibers

• deep body organs, dull, aching pain

• unmyelinated

Pain Pathway

1. Stimuli → Nociceptors

2. Pain → dorsal horn

3. SpinoTHALAMIC tract → Thalamus → Postcentral gyrus (Aware of pain) (5)

4. SpinoRETICULAR tract → hypothalamus & limbic (emotional & behavioural response) (6)

Referred Pain

• Pain at location other than site of stimulus

• Happens bcs sensory fibers from organ & the skin converge

Analgesics

Pain relievers

Warm receptors

• dermis

• Activated above 25*C

• > 48*C → burning

Cold receptors

• Epidermis

• 20*C - 30*C

1. < 10*C → less signals

2. Anesthetic

3. Pain receptors activate

Proprioceptors (Where & what)

• skeletal, muscle, joints, & tendons,

• Body movement, muscle stretch, position

• Inner ear → balance

Gustation

Chemicals on taste buds

Papillae (What does it contain & where is it found)

• Protrusions on tongue

• Taste buds are found ALONG & BETWEEN papillae

Vallate papillae

• Large papillae at back of tongue

• Have half of taste buds

Foliate papillae

Sides of tongue

Filiform papillae

• Thread-like

• Figure out texture of food

• NO taste buds

Fungiform Papillae

Tip & sides of tongue

Fill in the blank

1. taste

2. saliva

3. stimulate

4. cranial nerves

5. facial (VII)

6. glossopharyngeal nerve (IX)

7. Vagus nerve (X)

Where are olfaction receptor cells?

Roof of nasal cavity → ethmoid bone pores → CN I

What are steps 1 to 4

1. Odour binds to cilia projecting from ends of receptor cells

2. Signal → nerve fibers in ethmoid bone pores

3. Fibers → glomeruli (olfactory bulbs) => partial impulse processing

4. Signal → primary olfactory cortex

Auricle/Pinna (What is it & function?)

• Visible part of ear

• Funnel sound → auditory canal

Where does the auditory canal start/end?

Temporal bone → eardrum

External auditory meatus

Outside opening of auditory canal

What is cerumen? What does it do? (2)

Secretions from canal glands + dead skin cells

• Waterproof canal

• Traps dirt & bacteria

How does cerumen leave the ear?

Dries & propelled by jaw movements

Auditory ossicles

Middle ear

1. Malleus (hammer)

2. incus (anvil)

3. stapes (stirrup)

Oval window: Where inner ear begins, connected to stapes

Tympanic membrane (2)

• Separates outer & middle ear

• Vibrates freely w/ sound waves

Auditory/eustachian tube (3)

• Passageway from middle ear → nasopharynx

• Equalize pressure on both sides of eardrum

• Allows infection to spread from throat to middle ear

Bony labyrinth

• temporal bone passageways

• Houses inner ear

Membranous labyrinth

Lines inside bony labyrinth

Perilymph

Fluid that fills space b/w bony & membranous labyrinths

Endolymph

Fluid that fills inside membranous labyrinth

Semicircular canals

Equilibrium & balance

Vestibule

• Entrance to labyrinths

• Has balance organs

Cochlea

Hearing structures

Cochlear duct

• Triangular

• Filled w/ endolymph

Outer 2 compartments have perilymph

Organ of Corti

• Hearing (sensory & supporting cells + hair cells)

• Basilar membrane

• Hair cells form CN VIII

Tectorial membrane

Gelatin membrane on top of hair cells

How does hearing work?

1. Sound waves → external auditory canal → tympanic membrane vibrates

2. Vibration → malleus, incus, & stapes

3. Stapes vibrates oval window → perilymph fluid shakes

4. Perilymph moves cochlear duct → hair cells (Organ of Corti) are stimulated to send nerve impulse → CN VIII → auditory cortex → temporal lobe

5. Vibration dissipate by striking round window

Why are the 3 fluid-filled semicircular canals at right angles from each other?

Each canal can be stimulated by diff head movement

Ampulla (3)

• Bulb-like area at end of each canal

• Has hair cells at cupula

• Cupula: floats in endolymph in semicircular canals

Vestibule (3)

• Utricle & saccule: sense organs

• Tips of hair cells are covered by gel

• Otoliths: Mineral crystals embedded in gel

Dynamic equilibrium (2)

• Semicircular canals → endolymph moves & bends hair cells

• Detects speed & direction of head movement

Static equilibrium (2)

• Utricle & saccule → otoliths shift & bend hair cells

• Detect head position when stationary & acceleration in straight line

Eyebrow (3)

• Enhance facial expressions (nonverbal communication)

• Keep perspiration out of eye

• Shield eye from glare

Eyelids (palpebrae) (4)

• Orbicularis oculi muscle + skin

• Protect from foreign bodies

• Block light when closed for sleeping

• Periodic blinking washes out debris & moistens eyes w/ tears

Palpebral fissure

Opening b/w eyelids

Eyelashes (2)

• Keep debris out of eyes

• Touching lashes stimulate blink reflex

Conjunctiva (4)

• Transparent mucous membrane, lines inner surface of eyelid

• Covers anterior surface of eyeball EXCEPT cornea

• Secretes thin mucous film → keeps eyeball moist

• Vascular

Tarsal glands

• tarsal plate: thickened area of eye

• Secretes oil to slow evaporation of tears

• Forms barrier seal when eyes are closed

1. Eyebrow

2. eyelids

3. palpebral fissure

4. eyelashes

5. conjunctiva

6. tarsal glands

Lacrimal punctum

Lacrimal apparatus

• Tiny pore at end of lacrimal canals

• Drains tears → lacrimal canals & nasolacrimal duct

Lacrimal gland & tears (4)

Lacrimal apparatus

• Secretes tears that onto conjunctiva surface

Tears

• Clean & moisten eye’s surface & deliver O₂ + nutrients to conjunctiva

• Have lysozyme to prevent infection

Nasolacrimal duct

Carries tears → nasal cavity

Accomodation

Curvature of lens changes so eye can focus on near object

Adaptation

↓ of sensation that occurs after continuous exposure to stimulus

Sclera (3)

• Outermost layer, white part of eye

• Blood vessels & nerves run through sclera

Fibrous outer layer

Cornea

Allows light → eye (No blood vessels)

Fibrous outer layer

Iris

• Ring of coloured muscle

• Controls # of light entering eye

Vascular Middle layer

Ciliary body

• Thick extension of choroid, collar around lens

• Secretes aqueous humour

Vascular Middle Layer

Choroid

• Vascular tissue

• Supplies O₂ & nutrients → retina & sclera

Vascular Middle layer

Retina

Light-sensitive cells

Neural inner layer

CN II

• Exits posterior eyeball

• Sends signals → brain

Neural inner layer

Name 1-7

1. Sclera

2. Cornea

3. Iris

4. Ciliary body

5. Choroid

6. Retina

7. Optic Nerve

Macula lutea

Central point of retina

Fovea centralis

• Most of cones → sharpest vision

• No rods

Optic disc

• Blood vessels enter/leave eye

• Where nerve fibers join & form optic nerve

• Produces blind spot (no photoreceptors)

1. Macula lutea

2. Fovea centralis

3. Optic disc

Anterior cavity

• Space b/w lens & cornea

• Anterior chamber: front of iris, filled w/ aqueous humour

• Posterior humor: behind iris but in front of lens

Lens

Changes shape for near & far vision

Posterior cavity

Vitreous humor: semi-solid, keeps eyeball from collapsing