BSC 1086L Anatomy II Lab

Sensory Receptors

respond to changes in environment (in or ex)

activation leads to graded potentials → nerve impulses

sensation and perception occur in the brain

classification protocol → stimulus, body location, structural complexity

Special Senses

Confined to the head

Smell, taste, vision, hearing, and equilibrium

Supplied by cranial nerves

mechanoreceptors

touch, stretch, pressure, vibrations, motions

Thermoreceptors

Changes in temperature

Nociceptors

respond to pain

Chemoreceptors

respond to chemicals

photoreceptors

respond to light

Olfaction

Can detect around 10,000 different odors

Specialized receptor in superior nasal cavity

Olfactory sensory neurons

Ciliated to increase surface area

Concentrated receptors in olfactory BULB

End nerve (CN I)

Olfactory Epithelium

Bipolar Neurons (covered in mucus)

Bundles of NONmyelinated axons (filaments CN I)

Stem Cells (New Neurons every 30-60 Days)

Olfactory Pathway

Air → Receptor Stimuli → Signal Olfactory Tract to Cortex → Frontal Lobe or Limbic System/Hypothalamus

Olfactory Expantion

Frontal Lobe - Conscious perception and identification of smell

Limbic/Hypo - Emotional and behavioral response

Gustation

Sensory Organ = Taste Buds

Found in Papillae

Each Taste Bud includes 50-100 epithelial cells

(Gustatory Cell Receptors → Basal Stem Cells)

Gustatory Epithelial Cells

Microvilli = Gustatory Hairs

Hairs Project onto Taste Pores

(bathed in saliva)

Fungiform Papillae

Throughout the surface of the tongue

Vallate Papillae

Back of the tongue and the largest

Foliate Papillae

Long, thin, and throughout the tongue on the sides

Gustation Pathway

A tastant binds gustatory cells (MUST DISSOLVE IN SALIVA, sends information to the brain, different flavors become activated differently

What nerves are activated from gustation?

Facial Nerve (VII), Glossopharyngeal (IX), Vagus Nerve (X)

Sweet

Sugars, saccharin, alcohol, some amino acids, some lead salts

Sour

hydrogen in solution

Salty

Metal ions (inorganic salts); sodium chloride tastes saltiest

Bitter

Alkaloids (nicotine, caffeine) and nonalkaloids (aspirin)

Umami

Amino acids glutamate and aspartate

Gustation Taste Buds

Can have all 5 receptors for taste

Olfactory cilia

extend into mucus and bind odor molecules

Supporting cells

help support and protect olfactory receptor cells

Bowman’s glands

produce mucus that dissolves odor molecules

Olfactory bulb

first major processing center for smell

Olfactory tract

Carries information from the olfactory bulb toward the brain

Olfactory Pathway

odor molecules = olfactory receptors = olfactory nerve (CN I) = olfactory bulb = olfactory tract = olfactory cortex

Receptor cells

gustatory receptor cells are chemoreceptors located inside taste buds

taste buds = gustatory receptors cells = sensory nerve fibers

2nd Pathway of taste

Taste receptors = cranial nerves = medulla = thalamus = gustatory cortex

Vision Rods

Dim-light vision, black-and-white, very sensitive, important for night vision, poor detail

Vision Cones

Bright-light vision, color vision, high visual acuity/detail, concentrated heavily in the fovea centralis

Pathway of light

Cornea = aqueous humor = pupil = lens = vitreous humor = retina = photoreceptors

Vision NEURAL signal Travels

Photoreceptors = bipolar cells = ganglion cells = optic nerve (CN II) = optic chiasm = optic tract = thalamus = visual cortex

Cornea

refracts/ bends incoming light

sclera

white outer layer; protection/shape

Iris

Controls pupil size

Pupil

Opening that allows light in

Lens

Fine-focuses light onto retina

Ciliary muscles

changes lens shape for accommodation

Aqueous humor

Fluid in anterior eye; nourishes structures and maintains pressure

Vitreous humor

Gel filling posterior cavity; maintains shape

Retina

Contains photoreceptors

Choroid

Vascular/ pigmented layer; nourishes retina and absorbs stray light

Optic disc

exit point of optic nerve; blind spot

Fovea centralis

Area of sharpest vision; many cones

Macula lutea

Area responsible for central vision

Optic nerve

Carries visual information to brain

Fibrous tunic

sclera and cornea

Vascular tunic

Choroid, Ciliary Body, Iris

Neural Tunic

Retina

Superior Rectus

Elevates Eye

Inferior rectus

Depresses eye

Medial rectus

Moves eye medially

Lateral rectus

moves eye laterally

Superior oblique

depresses/ rotates eye

Inferior oblique

Elevates/ rotates eye

External Ear

Auricle (Pinna) collects sound

External Auditory canal

Conducts sound waves toward eardrum

Tympanic membrane

Eardrum; vibrates in response to sound

Middle Ear

MALLEUS = INCUS = STAPES

Malleus

Attached to tympanic membrane

Incus

Middle bone

Stapes

Pushes against the oval window

Auditory/Eustachin tube

Equalizes pressure between middle ear and throat

Inner Ear

Cochlea = Hearing

Vestibule

Static/ linear equilibrium

Semicircular canals

rotational/ angular equilibrium

Organ of Corti

Sensory organ for hearing

Hair cells

Mechanoreceptors that detect movement/vibration

Oval window

Receives vibration from stapes

Round window

Allows pressure relief within cochlea

Pathway of sound

Auricle = external auditory canal = tympanic membrane = malleus = incus = stapes = oval window = cochlea = organ of Corti = cochlear nerve = brain

Pathway of sound PT2

Sound waves = mechanical vibrations = fluid movement = hair-cell stimulation = nerve signal

Static equilibrium

Head position and Gravity

Main structure: utricle +saccule

Linear acceleration

movement in a straight line

(moving forward in a car)(elevator moving up/down)

Main Structure = utricle + saccule

Rotational/ angular accelration

head/body rotation

Main Structure = semicircular canals

Myopia

distant objects appear blurry because light focuses in front of the retina

Near = clear , Far = blurry

Hyperopia

Nearby objects appear blurry because light focuses behind the retina

Far = clearer, Near = blurry

Astigmatism

Irregular curvature of the cornea or lens causes light to focus unevenly, causes blurred or distorted vision

Hypothalamus

Releasing/ inhibiting hormones; ADH & oxytocin are produced here

Anterior pituitary gland

GH, TSH, ACTH, FSH, LH, PRL

Posterior pituitary

Release ADH and oxytocin

Thyroid

T3/T4, calcitonin

Parathyroid

PTH

Adrenal cortex

Aldosterone, cortisol, androgens

Adrenal medulla

Epinephrine, norepinephrine

Pancreas

Insulin, glucagon

Pineal gland

Melatonin

Thymus

Thymic hormones

Ovaries

Estrogen, progesterone

Testes

Testosterone

Hypothalamus

major regulator of the endocrine system, in control of the pituitary gland

Anterior pituitary

Hypothalamus releases releasing hormones into the hypophyseal portal system

hormones go to anterior and tell it what to release

Hypothalamus = CRH = Anteriro pituitary = TSH = thyroid = T3/T4

Posterior pituitary

The hormones ADH and oxytocin are produced by the hypothalamus

→ they travel down axons and are stored/ released by the posterior pituitary

Growth Hormone

Source = anterior P stimulates body growth and protein synthesis

Thyroid-stimulates hormone

Source = Anterior P stimulates thyroid to release T3/T4

Adrenocorticotropic hormone

Stimulates adrenal cortex especially cortisol secretion