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Olfactory System. Sense of Smell By: Hrag Peltekian & Matthew Park. Structure- Outer Part. The olfactory system is the sense of smell within eukaryotes.
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Olfactory System Sense of Smell By: HragPeltekian& Matthew Park
Structure- Outer Part • The olfactory system is the sense of smell within eukaryotes. • In humans, the outer skin part of the nose is made of the external meatus. It is the triangular shaped bone in between the eyes. This bone holds the shape of the nose. • The nostrils are separated into two sections by the septum. • The septum is made of cartilage, bone, and mucus membranes.
Structure- Inner Part • Inside the two sections are nasal passages. Within these passages are hairs that act like filters called cilia. • Also, the mucus membranes are lined up to assist the ciliaand clean unnecessary waste while breathing in oxygen. • The Olfactory Bulb is also located towards the inner part of the nose. The Olfactory Bulb is the part of the nose that sends signals to the brain to identify a certain smell.
Function • Can be divided into two parts: - Peripheral: Olfactory receptor sense external stimulus and encode it as electric signal in neurons. Signal travels along olfactory nerve. - Central: Signal terminates at olfactory bulb. Axons in the olfactory neurons tangle to form glomeruli, in which they contact dendrites of mitral cells that send the axons to the limbic system of the brain.
A person's sense of smell is driven by certain processes: • A molecule released from a substance, like the fragrance of a flower, must stimulate special nerve cells called olfactory cells (located high up in the nose) • Olfactory cells send information to the brain to identify the specific smell. • Interferences such as nasal congestion, nasal blockage, or damage to the nerve cells themselves can lead to loss of smell, even permanently. Olfactory receptors can regenerate, however.
Diseases/Disorders • One disease that is part of the olfactory system is called Anosmia. Anosmia is a disorder in which you lose the sense of smell. • Hyposmia is also a disorder, but this has a decreased ability to smell.
Dysomia, the disease in which one has a distorted smelling ability. Divided into three categories. • Parosmia- changed sense of order. It is usually an unpleasant smell. • Phantosmia- senses odor when no odor present. • Agnosia- able to sense odors but unable to identify or differentiate smells.
Human receptors can detect up to 5,000 odors, rather than having different receptors for specific odors. • Women detect odors more easily than men.
Quiz • Which nerve cells detect odors? • Dendrite cells • Glomeruli cells • Olfactory cells • Brain cells
Quiz Answer: C. Olfactory Cells
Quiz 2. _____ in the olfactory cells tangle to form glomeruli. • Dendrites • Axons • Bulbs • Fragrances
Quiz Answer: B. Axons
Quiz • Olfactory receptors can regenerate. • True • False
Quiz Answer: A. True
Quiz • Which of the following statements is not true? • Olfactory receptors detect odors to send to the brain • The brain identifies the specific odor • The olfactory system consists of two parts, peripheral and central • Humans have different receptors for different odors
Quiz Answer: D. Humans have different receptors for different odors
Quiz • Which of the following is true? • Women detect odors more easily than men • Men detect odors more easily than women • Men and women have an equal ability to detect odors • A person’s sex does not affect his/her ability to detect odors
Quiz Answer: A. Women detect odors more easily than men
Quiz 6. The septum is made of which of the following: • Bone • Cartilage • Mucus Membrane • All of the above
Quiz Answer: D. All of the above.
Quiz 7. Dysomia is the disorder in which: • No smell is detected • Lessened sense of smell • Distortion of smell • Olfactory Bulbs do not work
Quiz Answer: C. Disorder of smell.
Quiz 8. Humans can detect up to how many smells? • 500 • 50 • 5 • 5000
Quiz Answer: D. 5000
9. The outer part of human noses which hold the shape of the nose are made up of: • Mucus • External Meatus • Olfactory Cells • Olfactory Bulbs
Quiz Answer: B. External Meatus
Quiz 10. What is the function of the cilia? • Identify the smell of an odor. • Send signals to the brain of a smell. • Block the nasal passage. • Filter the debris about to enter the inner part of the nose.
Quiz Answer: D. Filter the debris about to enter the inner part of the nose.
Bibliography • Anosmia: Symptoms, Causes, and Treatments. WebMD. Web. 12 May 2013. <http://www.webmd.com/brain/anosmia-loss-of-smell>. • Olfactory System Quiz Preparation.Quizlet, n.d. Web. 13 May 2013.<http://quizlet.com/21562892/quiz-3-preparation-unit-1-the-olfactory-system-flash-cards/>. • Disorders of Taste and Smell. WebMD. 12 August 2012. <http://emedicine.medscape.com/article/861242-overview> • Nose Structure. Bayer HealthCare LLC. <http://neosynephrine.com/nose_structure.html>