BIO 1004, Chapter 9 Notes
BIO 1004, Chapter 9 Notes BIO 1004
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This 3 page Class Notes was uploaded by Falyn Ruby on Wednesday February 24, 2016. The Class Notes belongs to BIO 1004 at Mississippi State University taught by Jeffery Echols in Spring 2016. Since its upload, it has received 29 views. For similar materials see Anatomy & Physiology in Biology at Mississippi State University.
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Date Created: 02/24/16
Anatomy and Physiology Chapter 9 Notes The Sensory System Sensory Organs contain neurons capable of generating an electrical impulse o These neurons are called receptors o General receptors are receptors that are sensitive to temperature, pain, and pressure. They are found in the skin, viscera/organs, muscles and joints. The ones found in the viscera/organs are much more sensitive than the ones found in the skin. These receptors sense pressure and presence of different chemicals. o Chemoreceptors are receptors that are sensitive to chemicals in the environment. Each chemical that you are sensitive to has a different receptor. Nerve endings that are sensitive to chemicals in the environment and when stimulated, they conduct an electrical impulse that is sent to the brain to be processed. Sense of Taste (gustation) Our sense of taste consists of taste bud that are located on the tongue, in the back of the throat, and on the roof of the mouth. All of these taste buds eventually form together to form a cranial nerve. Sense of smell (olfaction) Our sense of smell is much more sensitive than our sense of taste and it is the most primitive of all the senses. Located in the upper portion of the nasal cavity, smell receptors are stimulated by specific chemicals which then generates an electrical impulse that travels to the brain through a cranial nerve, where the information is processed. The brain has a different location for receiving information from olfactory cells – the olfactory bulb. o Located just above the nasal cavity o This fact makes olfaction unique. o Photoreceptors are stimulated by light to produce an electrical impulse that travels to the brain through a cranial nerve, where the information is processed. Accessory organs of the eye Extrinsic muscles are skeletal muscles that allow for movement of the eye. Our eyelids and eyelashes offer protection. Lacrimal apparatus: o Our lacrimal glands produce tears. o Our lacrimal ducts start in the corner and empty into the nose. Structure of the eye o The sclera is the white part of the eye and forms a capsule made up of connective tissue. o The choroid layer is the middle layer of tissue in the eye that absorbs stray light rays. o The retina is the inner layer that contains photoreceptors. There are two types of photoreceptors: o Rods are stimulated by low light and allow us to see black and white. Located around the fovea. o Cones are stimulated by more intense light and allows us to see colors. Located in the fovea. o Fovea o Optic Nerve o The iris is the colored portion of the eye and is the muscle that controls the size of the pupil. o The pupil is the hole in the center of the eye that lets light in. o The lens focuses light on the retina. o The cornea is the clear portion of the sclera that covers the front of the eye. Two chambers found in the eye: o The anterior chamber is smaller and is located between the cornea and the lens. Filled with aqueous humor fluid and is very watery. o The posterior chamber contains a gel-like fluid called vitreous humor, which maintains the shape of the eyeball. o Mechanoreceptors generate an electrical impulse in response to pressure. Outer parts of the ear: (all are exposed to the environment) The Pinna is cone shaped and concentrates sound waves. The ear canal is a tunnel that leads to the middle portion of the ear. The tympanum (ear drum) vibrates in response to sound waves. Middle ear: Contains 3 bones: malleus, incus, and stapes These three bones attach to the tympanum and cochlea and transmit vibrations The Eustachian tube is a hollow tube that connects the middle ear to the throat and equalizes pressure. o Also drains fluid. Most ear infections occur in the middle ear. Inner Ear: The cochlea is fused with the malleus, incus, and stapes. o Snail shaped o Fluid-filled o Lined with mechanoreceptors o Soundwaves pass over the mechanoreceptors to produce and electrical impulse to the bran Organs of balance are semi-circular canals and each ear has 3. Partially fluid-filled with small particles of bone floating on top Lined with mechanoreceptors.
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