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Special Senses are:
- Sight (eyes)
- Sound & equilibrium (ears)
- Taste (tongue)
- Smell (nose)
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General Senses are:
- Cutaneous senses
- heat/cold, pain, presssure/touch
- Visceral senses
- nausea, thirst, hunger
- urination/defecation
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6th Sense, Controversial
ESP
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External structures of the eye
Orbit
- cone shaped cavity (formed by skull)
- houses & protects the eyeball
- padded w/ fatty tissue
- eyeball connected by 6 short muscles
- covered by eyelid
- contain sebaceous glands (secrete sebum)
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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
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External structures of the eye
Lacrimal Apparatus
produces and stores tears
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External structures of the eye
lacrimal gland
transports tears
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External structures of the eye
Tears
- constant cleaning & lubrication
- act as an antiseptic
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Internal structures of the eye
Eyeball separated into 2 chambers of fluid called "humors"
- 1. Aqueous Humor - water
- 2. Viterous Humor - jellylike fluid
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Internal structures of the eye
Aqueous Humor
- "Watery" humor
- bathes the iris, pupil and lens
- fills the anterious and posterior chambers of the eye
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Internal structures of the eye
Vitreous humor
- clear, jellylike fluid
- occupies the entire eye cavity behind the lens
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Sclera
- outermost laer
- tough, fibrous tissue
- protective shield ("whites of the eyes")
- contains the cornea
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Cornea
- transparent to allow light rays to pass into the eye
- curved surface allowing them to bend the incoming light rays
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Choroid
- Middle layer
- Highly vascularized (rich blood supply)
- Pigmented region that provides nourishment to the eye
- Contains the iris and the pupil
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Iris
colored ring of tissue whose muscles contract or relax to change the size of the pupil in the center of the iris
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Pupil
Round opening in the iris that allows light rays to enter the intenal eye
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Lens
- Located behind pupil
- Clear, hard disk in the internal eye. The muscles and ligaments of the ciliary body change its shape to focus light rays onthe retina
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Retina
- 3rd layer of the eyeball
- contains the nerve endings that receive and help interpret the rays of light as images
- delicate membrane that continues posteriorly and joins the optic nerve
- contains light sensing receptors called rods and cones
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Rods
- Light sensitive cells in the retia.
- Detect black and white and function in daytime and nighttime vision
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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.
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Ciliary Muscles
Smooth muscle that alters the lens of the eye to accommodate for near vision
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Photopigments
Chemicals in the retinal cells that have light sensitivity
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Structure of the Ear
- External ear
- Middle ear or tympanic cavity
- Inner ear
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External Ear
- 1. Pinna/ Auricle leads sound waves into the auditory canal or external auditory meatus
- 2. Contains cerumen (earwax) to lubricate and protect the ear
- 3. At the end of the canal is the eardrum or tympanic membrane
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Middle Ear (Tympanic Cavity)
- 1. Contains the 3 smallest bones in the body (ossicles)
- 2. Ossicles amplify the sound waves
- 4. Eustachian tubes
- 4. Oval window begins the inner ear
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Ossicles
- Hammer (malleus)
- Anvel (incus)
- Stirrup (stapes)
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Eustachian Tubes
- Equalize the air pressure on either side of the eardrum
- Connect the nasal cavity and pharynix to the middle ear
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Inner Ear
- Oval Window
- Bony labyrinth
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Bony labyrinth
- 1. Vestibule Chamber (houses the internal ear)
- 2. Cochlea
- 3. Semicircular canals
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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)
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Perilymph
Pale lymph fluid found in the labyrinth of the inner ear.
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Endolymph
Fluid within the labyrinth of the ear.
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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.
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Bone conduction
Middle ear amplifies the sound through ossicles
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Sound Conduction
Sound waves enter the external canal and vibrate the eardrum
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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)
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Smell
- Closely related to taste (cannot taste food well with head cold)
- Linked to memory
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Touch (receptors called tactile corpuscles)
- Located on skin, tipe of tongue and concentrated in the fingertips
- Allows perception of pain, temperature, pressure, traction and "tickled"
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Semicircular canals in the ear
responsible for equilibrium
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Endocine translated means
- endo - into
- crine - to secrete
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endocrine system
a series of organs and glands in your body that secretes chemical messengers called hormones into the bloodstream
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glands that bridge the endocrine and nervous systems
- hypothalamus
- pituitary gland
- pineal gland
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chemical messengers
- neurotransmitter
- hormones
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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
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positive feedback
increases the magnatude of a change away from the set point; vicious cycle.
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Homone levels can be contolled by:
- Nervous system - neural control
- Hormones - hormonal control
- Body fluids (ie blood) - humoral control
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The Hypothalamus
- Is a link between the nervous and endocrine systems
- Controls much of the body's physiology, including hunger, thirst, fluid balance, body temperature
- Controls the pituitary gland
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Pituitary gland
- Often called the master gland
- But only acts on orders from the hypothalamus
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Posterior Pituitary
- An extension of the hypothalamus
- Launches 2 hormones for the hypothalamus
- Antidiuretic hormone (ADH) and oxytocin
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Anterior Pituitary
Also controlled by the hypothalamus, but is an endocrine gland too
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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)
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Thymus Gland
- produces thymosin
- helps with the maturation of WBC during childhood to fight infection
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Pineal Gland
- produces melatonin
- thought to regulate sleep
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Pancreas
- produces insulin & glucagon
- controls blood glucose levels
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Adrenal Glands
- The Adrenal Medulla
- The Adrenal Cortex
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Adrenal Medulla
produces epinephrine (adrenalin) and norepinephrine
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Adrenal Cortex
- makes dozens of steroid hormones known as adrencorticosteroids
- releases hormones under the direction of the anterior pituitary
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Parathyroid glands
produce parathyroid hormone (PTH) that regulates the level of calcium in the bloodstream
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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)
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