Special Senses and Lymphatic System PDF

SPECIAL SENSES The Special senses are the senses that have specialized organs devoted to them. It includes: 1. Sight 2. Hearing and Equilibrium 3. Taste 4. Smell SIGHT...

SPECIAL SENSES The Special senses are the senses that have specialized organs devoted to them. It includes: 1. Sight 2. Hearing and Equilibrium 3. Taste 4. Smell SIGHT EXTERNAL AND ACCESSORY PARTS The eye is our organ of sight. They are the organs that allow you to see. EYELIDS They take in light from the world around you and send visual - are thin soft tissue structures that cover and protect the anterior information to your brain. surface of the eyeball. o Nearly 70% of all the body receptors are in the eyes - The main role of the eyelids is to protect the eye. o a sphere that measures about 1 inch in diameter - It's vital that the surface of the eye (the cornea) remains constantly moist, so the eyelid is responsible for spreading the tear film evenly IMPORTANT PARTS OF THE EYE across the surface. - When we sleep, the eyelids don't simply block out light, they keep SCLERA the cornea from drying out. - the white of the eye or the white outer layer of the eyeball. EYELASHES - functions as the supporting wall of the eyeball. - the short hairs that grow along the edge of our eyelids- are our first - helps maintain your eyeball's shape, and protects it from injury. line of defense for your eyes, keeping airborne dirt, dust, lint CORNEA and other debris from reaching the delicate eye tissues. - acts as the eye's outermost lens. It functions like a window that - With eyes open, eyelashes catch some airborne debris, but when controls and focuses the entry of light into the eye. closed, eyelashes form a nearly impenetrable barrier against foreign - the cornea contributes between 65-75 percent of the eye's total irritants in the eye. focusing power. CONJUNCTIVA RETINA - is a transparent mucous membrane that lines both the inner surface - a thin layer of tissue that covers approximately 65 percent of the of the eyelids and the anterior surface of the eyeball (except back of the eye, near the optic nerve. the cornea). - Its job is to receive light from the lens, convert it to neural signals - Provides protection and lubrication of the eye by the production of and transmit them to the brain for visual recognition. mucus and tears. IRIS - Prevents microbial entrance into the eye and lines the inside of the - the colored part of the eye which helps regulate the amount of light eyelids and provides a covering to the sclera. entering the eye. - has 2 parts: - When there is bright light, the iris closes the pupil to let in less light. 1. Bulbar - lining the anterior eye - And when there is low light, the iris opens up the pupil to let in more 2. Palpebral – lining the eyelids light. PUPIL LACRIMAL GLAND - its function is clearly that of controlling the amount of light entering - Situated on lateral end of each eye. the eye, and hence the light reflex. - Produces lacrimal fluid (tears); LENS - is located in the eyeball. - By changing its shape, the lens changes the focal distance of the eye. - In other words, it focuses the light rays that pass through it (and onto the retina) in order to create clear images of objects that are positioned at various distances MACULA - located near the center of the retina; - its function is to process sharp, clear, straight-ahead vision. VITREOUS HUMOR - is a transparent, colorless, gelatinous mass that fills the space in the eye between the lens and the retina. - helps maintain the round shape of the eye and can also help with vision clarity and shock absorbance. - Most importantly, it helps it to hold its 'spherical' shape. - Responsible for about 80% of the volume of your eye AQUEOUS HUMOR - transparent, colorless, gelatinous mass - flows in and out of the front of your eye. - its job is to keep proper ocular pressure (eye pressure) in your eye.  TEARS Has 3 parts: 1. Cochlea is a clear liquid secreted by the lacrimal glands. o A hollow, spiral-shaped bone found in the inner ear Tears contain: o Plays a key role in the sense of hearing and participates in Dilute salt solution the process of auditory transduction. Mucus o Sound waves are transduced into electrical impulses that Antibodies the brain can interpret as individual frequencies of sound Lysozyme (enzyme that destroys bacteria) 2. Vestibule Function of Tears: o Best described as the area of the inner ear between the Cleanse tympanic cavity and posterior to the cochlea. Protect o controls our equilibrium and balance. Moisten 3. Semicircular canal Lubricate the eye o Your semicircular canals are three tiny, fluid-filled tubes in your inner ear that help you keep your balance. HEARING AND BALANCE o When your head moves around, the liquid inside the THE EARS semicircular canals sloshes around and moves the tiny - the organ of hearing and balance. hairs that line each canal - are paired organs, located on each side of your head, - divide into 3 sections: A. External ear B. Middle ear C. Internal Ear ANATOMY OF THE EARS EXTERNAL EAR External ear is involved only in collecting sound waves. It is composed of the following: 1. Auricle - shell shaped structure surrounding the auditory canal opening. 2. External Acoustic Meatus - narrow chamber in the temporal bone. Lined with skin and ceruminous (earwax) glands. Ends at the tympanic membrane (eardrum). EQUILIBRIUM MIDDLE EAR An Air-filled, mucosa-lined cavity within the temporal bone. Is a state of balance. It is Involved only in the sense of hearing. Equilibrium does not see, hear or feel. Located between tympanic membrane and oval window and round window. What it does is to respond to various head movements. - made up of auditory ossicles Receptors of the inner ear are called the vestibular apparatus Vestibular apparatus has two functional parts AUDITORY OSSICLES: 1. Static equilibrium – no movement - functions to transmit vibrations from tympanic membrane to the 2. Dynamic equilibrium - moving fluids of the inner ear SMELL AND TASTE 1. Malleus (hammer) o also called hammer- is the largest, and most lateral of the Involves 2 organs: bony chain. 1. Tongue o It is a club-shaped structure 2. Nose o functions with the other bones to transmit vibrations from the eardrum to the inner ear. OLFACTORY RECEPTOR AND THE SENSE OF SMELL 2. Incus (Anvil) o also called Anvil The faculty or power of perceiving odors or scents by means of the organs in o the middle of three small bones in the middle ear. the nose. Nose is the organ of smell. o The incus transmits vibrations from the malleus to the stapes. HOW DO WE SMELL 3. Stapes (Stirrup) o also called stirrup Vaporized odor molecules (chemicals) floating in the air reach the o the smallest bone in the human body. nostrils and dissolve in the mucus (which is on the roof of each o the innermost (most medial and nearest to the cochlea of nostril). the ossicles inside the middle ear.) Underneath the mucus, in the olfactory epithelium, specialized receptor cells called olfactory receptor neurons detect the odor The olfactory receptor neurons transmit the information to the INNER EAR olfactory bulbs, which are located at the back of the nose. Also called the Labyrinth of the ear Includes sense organs for hearing and The olfactory bulbs have sensory receptors that are actually part of balance. the brain which send messages directly to the brain.  These brain centers perceive odors and access memories to remind THE LYMPHATIC SYSTEM us about people, places, or events associated with these olfactory sensations. The tissues and organs that produce, store, and carry white blood cells that TASTE fight infections and other diseases. It is also a Drainage System because it facilitates the return of the excess fluids The sensation of flavor perceived in the mouth and throat on contact from the cells back to the blood vessels. with a substance. The tongue is the organ of taste. Is a network of organs, vessels and tissues that work together to move a Humans have taste receptors on taste buds and other areas colorless, watery fluid (lymph) back into your circulatory system (your including the upper surface of the tongue and the epiglottis. bloodstream). Taste has Five Types of Receptors MAIN FUNCTIONS: 1. Salty 2. Sweet 1. Collecting excess fluid from your body’s tissues and returning it to 3. Bitter your bloodstream 4. Sour 2. Helping your body absorb fats 5. Umami (delicious and savory) 3. Protecting your body against invaders. TASTE BUDS AND THE SENSE OF TASTE LYMPHOID ORGANS Taste buds are sensory organs that are found on your tongue and allow you to LYMPHATIC VESSELS - A thin tube that carries lymph (lymphatic fluid) and white blood cells experience tastes that are sweet, salty, sour, and bitter. It houses the receptor through the lymphatic system. organs of taste. LYMPHS - Is the fluid that flows through the lymphatic system. - Similar but not identical to that of blood plasma. - Lymph that leaves a lymph node is richer in lymphocytes than blood plasma is. LYMPH NODES - are small glands that filter lymph through lymph vessels. - They become swollen in response to infection and tumors. - Most lymph nodes are kidney-shaped, less than 1 inch long, and buried in connective tissue. - Surrounded by a capsule. - Nodes are divided into Compartments: o Cortex (outer part) contains follicles—collections of lymphocytes. Germinal centers enlarge when antibodies are released by plasma cells o Medulla (inner part) contains phagocytic macrophages o Macrophages—engulf and destroy bacteria, viruses, and other foreign substances in lymph Locations of Lymph Nodes in the Body:  OTHER LYMPHOID ORGANS SPLEEN - It is a soft organ located on the left side of the abdominal cavity. - It filters and cleanses blood of bacteria, viruses and other debris. - Most important function is to destroy worn out RBC’s and return some of its breakdown products to the liver. - Ex iron – used again in making hemoglobin. THYMUS - a lymphoid mass found in the anterior mediastinum overlying the heart. - is responsible for producing and maturing lymphocytes, or immune cells. - these include T cells, a type of white blood cell that defends the body from infections. TONSILS - Small masses of lymphoid tissue deep to the mucosa surrounding the throat - Its job is to trap and remove bacteria entering the throat. PEYER’S PATCHES - Are found in the wall of the intestine. - Captures and destroys bacteria.