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


ESP


External structures of the eye
Orbit


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
Conjunctiva


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
Tears


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


sclerachoroidretina


Sclera


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


Cornea


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


Choroid


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


Iris


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


Pupil


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


Lens


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


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


Rods


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


Cones


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


Photopigments


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


Ossicles


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


Cochlea


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)


Perilymph


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


Endolymph


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)


Smell


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


Pancreas


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)