Ch 11 & 12

Special Senses are:

Sight (eyes)Sound & equilibrium (ears)Taste (tongue)Smell (nose)

General Senses are:

Cutaneous sensesheat/cold, pain, presssure/touchVisceral sensesnausea, thirst, hungerurination/defecation

6th Sense, Controversial


External structures of the eye

cone shaped cavity (formed by skull)houses & protects the eyeballpadded w/ fatty tissueeyeball connected by 6 short musclescovered by eyelidcontain sebaceous glands (secrete sebum)

External structures of the eye

protective membrane that lines the exposed surface of the eyeball and acts as a protective covering for the exposed eye surface

External structures of the eye
Lacrimal Apparatus

produces and stores tears

External structures of the eye
lacrimal gland

transports tears

External structures of the eye

constant cleaning & lubricationact as an antiseptic

Internal structures of the eye
Eyeball separated into 2 chambers of fluid called "humors"

1. Aqueous Humor - water2. Viterous Humor - jellylike fluid

Internal structures of the eye
Aqueous Humor

"Watery" humorbathes the iris, pupil and lensfills the anterious and posterior chambers of the eye

Internal structures of the eye
Vitreous humor

clear, jellylike fluidoccupies the entire eye cavity behind the lens

Eyeball has 3 layers



outermost laertough, fibrous tissueprotective shield ("whites of the eyes")contains the cornea


transparent to allow light rays to pass into the eyecurved surface allowing them to bend the incoming light rays


Middle layerHighly vascularized (rich blood supply)Pigmented region that provides nourishment to the eyeContains the iris and the pupil


colored ring of tissue whose muscles contract or relax to change the size of the pupil in the center of the iris


Round opening in the iris that allows light rays to enter the intenal eye


Located behind pupilClear, hard disk in the internal eye. The muscles and ligaments of the ciliary body change its shape to focus light rays onthe retina


3rd layer of the eyeballcontains the nerve endings that receive and help interpret the rays of light as imagesdelicate membrane that continues posteriorly and joins the optic nervecontains light sensing receptors called rods and cones


Light sensitive cells in the retia. Detect black and white and function in daytime and nighttime vision


Light sensitive cells in the retina that detect colored light.three types of cones, each of which responds to either red, green or blue light.

Ciliary Muscles

Smooth muscle that alters the lens of the eye to accommodate for near vision


Chemicals in the retinal cells that have light sensitivity

Structure of the Ear

External earMiddle ear or tympanic cavityInner ear

External Ear

1. Pinna/ Auricle leads sound waves into the auditory canal or external auditory meatus2. Contains cerumen (earwax) to lubricate and protect the ear3. At the end of the canal is the eardrum or tympanic membrane

Middle Ear (Tympanic Cavity)

1. Contains the 3 smallest bones in the body (ossicles)2. Ossicles amplify the sound waves4. Eustachian tubes 4. Oval window begins the inner ear


Hammer (malleus)Anvel (incus)Stirrup (stapes)

Eustachian Tubes

Equalize the air pressure on either side of the eardrumConnect the nasal cavity and pharynix to the middle ear

Inner Ear

Oval WindowBony labyrinth

Bony labyrinth

1. Vestibule Chamber (houses the internal ear)2. Cochlea3. Semicircular canals


Structure of the inner ear that is associated with the sense of hearing. It relays information to the brain via the cochlear branch of the vestibulocochlear nerve (cranial nerve VIII)


Pale lymph fluid found in the labyrinth of the inner ear.


Fluid within the labyrinth of the ear.

Sensorineural conduction

Last ossicle vibrates and cuases a gentle pumping against the oval window membrane. Cochlear fluid then vibrates small hairlike neurons. Vibration sends a nerve impulse to the temporal lobe of the brain.

Bone conduction

Middle ear amplifies the sound through ossicles

Sound Conduction

Sound waves enter the external canal and vibrate the eardrum

Taste (gustatory sense)

Papillae contain taste receptors called taste buds. Found on tongue, lips and back of the throat.Taste buds send signals to the brain thru 3 distinct cranial nerves.Detect 5 tastes: sweet, sour, salty, bitter and umami (savory)


Closely related to taste (cannot taste food well with head cold)Linked to memory

Touch (receptors called tactile corpuscles)

Located on skin, tipe of tongue and concentrated in the fingertipsAllows perception of pain, temperature, pressure, traction and "tickled"

Semicircular canals in the ear

responsible for equilibrium

Endocine translated means

endo - intocrine - to secrete

endocrine system

a series of organs and glands in your body that secretes chemical messengers called hormones into the bloodstream

glands that bridge the endocrine and nervous systems

hypothalamuspituitary glandpineal gland

chemical messengers

neurotransmitter hormones

negative feedback

the control systems work to bring the body back to homeostasis if they become seriously disrupted. ie when hot, body send blood to the surface of the skin to promote sweating, thus reducing the heat

positive feedback

increases the magnatude of a change away from the set point; vicious cycle.

Homone levels can be contolled by:

Nervous system - neural controlHormones - hormonal controlBody fluids (ie blood) - humoral control

The Hypothalamus

Is a link between the nervous and endocrine systemsControls much of the body's physiology, including hunger, thirst, fluid balance, body temperatureControls the pituitary gland

Pituitary gland

Often called the master glandBut only acts on orders from the hypothalamus

Posterior Pituitary

An extension of the hypothalamusLaunches 2 hormones for the hypothalamusAntidiuretic hormone (ADH) and oxytocin

Anterior Pituitary

Also controlled by the hypothalamus, but is an endocrine gland too

Thyroid gland

Secretes thyroxine (T4) and triiodothyronine (T3) under orders from the pituitary gland ("thyroid hormones")Also secretes calcitonin (decreases blood calcium by stimulating bone building cells)

Thymus Gland

produces thymosinhelps with the maturation of WBC during childhood to fight infection

Pineal Gland

produces melatoninthought to regulate sleep


produces insulin & glucagoncontrols blood glucose levels

Adrenal Glands

The Adrenal MedullaThe Adrenal Cortex

Adrenal Medulla

produces epinephrine (adrenalin) and norepinephrine

Adrenal Cortex

makes dozens of steroid hormones known as adrencorticosteroidsreleases hormones under the direction of the anterior pituitary

Parathyroid glands

produce parathyroid hormone (PTH) that regulates the level of calcium in the bloodstream

Common Disorders of the Endocrine System

Anabolic Steroids Hashimoto's disease (a form of hypothyroidism) Graves' disease (hyperthyroidism) Pheochromocytoma (excess epinephrine) Addison's disease (insufficient cortisol production) Cushing's syndrome (oversecretion of cortisol)