Recent Changes

Sunday, September 5

  1. user_add AllanC AllanC joined bohone
    8:51 pm

Wednesday, August 20

  1. 12:28 am

Monday, July 28

  1. page Group4 edited E-facilitator: Cathy Snelling Learning Outcomes define, compare and contrast the structure and l…
    E-facilitator: Cathy Snelling
    Learning Outcomes
    define, compare and contrast the structure and location of endocrine and exocrine glands
    discuss the physiology of both types of gland
    Every cell must communicate with another one in the body in order to function effectively. Most of the communication involves the release and rceipt of chemical messages. This communication betwen cells is done by releasing chemicals into the extracellular fluid and this is further spread to the neighbor cells to let them know wht those cells are doing and this leads to the cooperation of tissue functions. While the nevous system acts like a phone agency to carry information from one location to another; this is important when crisis happens suddenly like being passed infront of a car so the nervous system can send immediate messages and we can safe our life. As mentioned above, cells communicate by releasing chemicals. In cellular communication; hormones act as an addressed letters while the circulatory system act as the postal service.
    {hormone_1.gif} Group 4 A Comparative Study of Endocrine and Exocrine {hormone_2.gif} E-Facilitator: Cathy
    (image of hormonal action,
    Once the hormones are released into the circulatory system, they will be distributed throughout the body and each hormone will appraoch certain cell as a target which will respond to it's presence. These cells have the receptors needed to bind and respond to the hormonal messages. Cells are usually respond to only those hormones they can bind and read and the other hormones will be treated as a junk mail and will be ignored.
    Physiology of the endocrine system:
    The chemicals that are released by the endocrine cells may affect only adjacent cells as in the case of the local hormones which are known as postglandins; or they might affect cells throughout the body. As mentioned above, hormones are the chemical messengers that are released in one tissue and carried into the circulation to reach target cells in other tissues. These hormones of the endocrine system are either produced in organs that have endocrine secretions as the main function, such as the pituitary gland; while others have many functions in addition to endocrine secretion, such as the pancreas.
    Hormones can be divided into 3 different groups: Amino acid derivatives, Peptide hormones (chains of amino acids), lipid derivatives. The structure and functions of all cells are determined by proteins. These proteins determine the general shape and internal structure of a cell. and the enzymes direct its metabolic activities.Hormones change the operations of cells by altering the activities, identities of important enzymes and structral proteins in target cells. The presence or abscence of a specific ( receptor complex) deterimine the sensetivity of the target cell and this is either on the cell membrane or in the cytoplasm with which the hormones act or interact.
    (Martini, F.H, Bartholomew, E.F 1997, Essentials of Anatomy and Physiology, Prentice Hall, Upper Saddle River, New Jersey, USA).
    There are 2 types of hormonal actions: Non-Steroid hormones and Steroid hormones:
    Non-steroid hormones: or (water soluble hormones) which bind with plasma membrane receptors to triger a chemical signal inside the target cell. Those second messagners or chemical signals triger then other intracellular chemicals to produce a response of a target cell as shown below in the images: {first_1.gif} {first_1.gif}
    {first_3.gif} {first_4.gif}
    ( action of steroid hormones,
    Steroid hormones: those hormones pass through the plasma membrane. Once they enter into the membrane, they firstly bind with the nuclear membrane receptors to form an activated-receptor complex. The activated-receptor complex then binds to DNA to activate certain genes like mRNA to increase protein production as shown in the images below: {steract_1.gif} {steract_2.gif}
    ( images of steroid action,
    The Physiology of te exocrine glands:
    As mentioned before, the exocrine glands release their chemical messages through the ducts and this is done by the secretory cells of each gland that empty or release their components into the ducts. The ducts usually empty into an anatomical surface. There are 3 types of modes in which the exocrine glands release their products, those modes are:
    The merocrine method: In this method, the secretory cells form a (membrane-bound secretory vesicles) inside the cell itself. Those vesicals are then carried into the apical surface and come together with the membrane of that apical surface to release the product as shown in the image: {merocrine.gif}
    The apocrine method: In the sercretory process the apical parts of the secretory cells are slashed and lost. Those portions usually contains molecular contents which includes those of the membrane as well. A good example of this method is the mammary glands. {apocrine.gif}
    The holocrine method: In this method the secretory cells die and they are released with their components which represent the secretory products. For example, sweat glands of the axillae, pubic areas and around the areoli of the breasts. also sebaceous glands are another example of this method. {holocrine.gif}
    (images and contents are from,
    .present an example of how each type of gland affects the oral environment.
    There are 2 types of glands, exocrine and endocrine glands. Exocrine glands produce nonhormonal substances, such as saliva and sweat and have ducts through which those substances can flow to a surface; while endocrine glands produce hormones and do not have ducts.
    An example of exocrine glands that play a major role in oral environment are salivary glands and they produce saliva. Saliva is produced by three major glands ( parotid, submandibular and sublingual glands) and numerous minor glands which are located within the oral cavity. Saliva has many functions such as:
    buffering capacity :saliva contains 3 buffer systems( bicarbonate, phosphate and protein). Saliva helps to keep an acceptable pH between 6.0-7.5 within the oral cavity.
    Reminerlization of teeth: by supersaturated components which are phosphate and calcium; thus, it prevents demineralization of the dentition. In addition saliva protein form pellicle which provides protection against irritants.
    Lubrication capacity : by salivary mucins which also act as a barrier against any microbial invasion.
    Repair of soft tissues
    Digestion: saliva contains amylase and lipase which digest starch and thus saliva plays a role in the intiation of digestion which begins in the oral cavity.
    Antimicrobial capacity: by salivary mucins, Lysozyme and lactoferrin. Lactoferrin has an antibacterial, antifungal and antiviral properties; also salivary peroxidase has antibacterial properties and histatins that have antibacterial and antifungal properties.
    Saliva also contains other components which are: glucose, urea, sex hormones and blood group substances which serves as a diagnostic and screening tools.
    ( Mostofsky, D.I, Forgione, A.G, Giddon, D.B 2006, Behavioral Dentistry, Blackwell Munksgaard, Iowa, USA).
    Endocrine glands produce hormones and over time loose their ducts (also known as ductless glands). the hormones are secreted via exocytosis.
    Hormones are steriodal or amino based mollecules released into the blood which act as chemical messengers to regulate specific body functions.
    Once secreated, the hormone enters the blood / lymphatic fluid and travels to specific target organs. The endocrine system is diverse so can also be refered to as the diffuse endocrine system.
    The endocrine system interacts with the nervous system to coordinate and integrate the activity of body cells.
    (image - module_anatomy/unit6_3_endo_glnds.html)
    {illu_endocrine_system.jpg} illu_endocrine_system.jpg
    Major endocrine organs :
    Pineal gland
    Pituitary gland
    Thyroid gland
    Thymus gland
    Adrenal gland
    Ovum / Testes
    (Marieb 2007 human anat & phis pearson benjamin cummings)
    Exocrine glands are relitavely uniform and numerous in amount. They secrete their products onto body surfaces or into body cavities. Unicellular glands are directly secreted by exocytosis and multicellular glands are secreted via an epithelium.
    Major exocrine glands:
    Saliva glands
    Many others
    (image of saliva glands - BiologyPages/E/ Exocrine Glands .html)
    {salivary_glands.gif} salivary_glands.gif
    Unicellular cell - Goblet cell, found in epithelial tissue- linings of intestinal and respritory tracts. Produce mucin, a complex glycoprotein which forms mucus for protective and lubricatory purposes.
    Multicellular cells - are complex and have 2 parts, a duct and secretory unit. Supportive connective tissue surrounds the secretory unit supplying it with blood vessels and nerve fibres, forming a fibrous capsule that extends into the gland dividing it into two lobes. Can be simple or compound. Simple cells have an unbranched duct and compound have a branched duct. Multicellular cells can be further categorised by secretory units
    *tubular - if secretory cells form tubes, *alveolar - if secretory cells form flasklike sacs, *tubuloalveolar - if both types.
    most multicellular glands are merocrine glands which secrete their products by exocytosis as they're produced (salivary glands are merocrine glands).Holocrine gland (skins sebaceous oil gland) accumulates its products within themselves until they rupture.
    Link to an excellent table on glands and their functions as the table can not be copied to this wiki.
    ( accessed 7/8/07
    ENDOCRINE GLANDS AND ORAL HEALTH: including what to do at the dentist:
    Oral Effects:
    People with uncontrolled diabetes can have:
    Rapidly progressing periodontal disease
    Xerostimia which may lead to caries progression
    Poor healing of oral tissues
    Oral candidiasis (oral thrush)
    Burning mouth and/or tongue
    The most common oral health problems associated with diabetes are:
    tooth decay
    periodontal (gum) disease
    salivary gland dysfunction
    fungal infections
    lichen planus and lichenoid reactions (inflammatory skin disease)
    infection and delayed healing
    taste impairment
    Oral Effects:
    Varying concentrations of radioactive iodine — used to assess and treat various forms of thyroid disease — can damage salivary gland tissue and cause swollen salivary glands and changes in salivation.
    Children with hypothyroidism — an underactive thyroid gland — may have malocclusion, as well as delayed tooth eruption, a protruding tongue, and thick lips. However, many children with hypothyroidism have none of these effects. It depends on the degree of the disease, the age at which the child was diagnosed and the time that passed before diagnosis.
    Adults with hypothyroidism may have an enlarged tongue and a hoarse voice.
    People with hyperthyroidism — an overactive thyroid gland — may have tooth decay, and rapid and severe periodontal disease.
    Oral effects
    People with tumors of the pituitary gland may have an increased production of growth hormone. Excess growth hormone can lead to gradual growth changes in facial structures containing cartilage, including the nose, ears and jaw. If a pituitary problem occurs after normal growth has stopped, the jaw may still grow, making it out of proportion to other facial structures. The lower jaw and/or the tongue may become progressively enlarged. Significant growth changes may affect denture fit.
    When this disease is undiagnosed, people may visit an orthodontist, thinking that braces can help with the tooth or jaw growth problems. Excess growth hormone can lead to heart disease (including high blood pressure) and diabetes.
    video on endocrine function

    (view changes)
    8:27 pm
  2. page Group12 edited Group 12 The Gag Reflex E-Facilitator: Cathy Contents for Wiki Learning Outcomes: The Anatomic…
    Group 12 The Gag Reflex
    E-Facilitator: Cathy
    Contents for Wiki
    Learning Outcomes:
    The Anatomical features involved in the gag reflex,
    The physiological mechanisms which occur that generate the response,
    Discuss why the gag reflex is present in a healthy individual - and the implications of the absence of one, and
    List and discuss strategies which can be implemented by a dental operator to alleviate symptoms in a gagging patient.
    *All information has been placed under the above headings in the form of paragraphs, dot points, diagrams and reference links.
    1. Describe the anatomical features involved in the gag reflex
    A reflex is defined as an automatic reaction to a stimulus, which can either be intrinsic or acquired. Intrinsic reflexes are rapid, predictable motor responses that are unlearned, inadvertent and involuntary. It involves an afferent impulse being transmitted from the stimulus site, through sensory neurons, to the central nervous system. The stimulus is then processed in order to generate/initiate an immediate motor response. Hence, this form of reflex prevents the individual from thinking about information which is necessary for survival. One such example is the gag reflex (10).
    The gag reflex is a reflex contraction of the soft palate. The soft palate is a mobile muscular attachment which is located posterior to the hard palate (see below). When the back of the oral cavity or pharynx is stimulated, cranial nerves V (trigeminal), IX (glossopharynxgeal) and X (vagus) are activated. Sensory neurons then transmit this afferent impulse to the central nervous system where it integrates the acquired information. An efferent impulse is then transmitted to the back of the throat, where the superior layngeal muscles contract, causing the gag reflex. The afferent limb of the reflex is supplied by the glossopharyngeal nerve (cranial nerve IX) and the efferent limb is supplied by the vagus nerve (cranial nerve X) (13).
    {nerve.png} Glossopharyngeal Nerve(13)
    When a food bolus is transported toward the back of the tongue it usually triggers an automatic series of muscle cotractions which are specificly designed to propel the food onwards through the pharynx and oesophagus. The stimulus provoking this process is primarily a mechanical one. If and when a mechanical stimulus is applied to the back part of the tongue or to the soft palate and the consequential motor response is unsuccessful in moving the food or dislodging the sorce of the stimulus, then a gag reflex is elicted. when this happenes the efforts of removal are increased followed quickly by movements of expolsion (13).
    The soft palate is elevated and by doing so closes off the nasal airway
    The jaw is lowered
    The back of the tongue is lifted followed by a forward sweep of the lifted part
    If there is a continued faliure to remove the source of the stimulus there may be retching and finally vomiting.
    {pharynx.jpg} Showing pharynx and palate2. Describe the physiological mechanisms which occur that generate the response
    The origin of the gag reflex is grouped as either somatic (reflex brought about by sensory nerve stimulation from direct contact) or psychogenic (from higher centres in the brain - beyond the scope of this report). In somatic gagging, when a trigger area is 'touched,' the gag reflex is induced. Even though trigger areas vary with each individual, the gag reflex is commonly elicited in sites such as the lateral border of the tongue and specific parts of the palate. Hence, when direct contact is made between these areas of the oral cavity, the gag reflex will be induced. This can either be;
    Individually induced, or
    Induced by someone else (e.g. dental operator)
    An individual may induce the gag reflex through activities such as brushing their teeth, eating food or placing objects into their own mouth that stimulate the gag reflex. Additionally, when an individual is at the dentist objects such as a mirror, probe, suction tip or other dental intruments may induce the gag reflex (13).
    Other physiological means include; (13)
    Nasal obstruction (e.g. nasal polyps)
    Gastrointestinal disorders
    Heavy smoking
    Incorrect fitting partial or full dentures
    Anatomy of the soft palate
    Catarrh (inflammation of mucous membranes, in particular of the nose and throat)
    Sinusitis (inflammation of one of the paranasal sinuses)
    Dry mouth (low saliva flow)
    Medications that cause nausea as a side effect (as nausea is a feeling of sickness in the stomach, an urge to vomit)
    Physiological causes which can predispose or cause a person to gag include not being able to breathe through your nose properly, catarrh, sinusitis, nasal polyps, mucus in the upper respiratory tract, a dry mouth, and medications that cause nausea as a side effect. Certain medical conditions (gastrointestinal diseases) can also contribute to gagging (13).
    3. Discuss why the gag reflex is present in a healthy individual - and the implications of the absence of one
    The gag reflex is the bodies natural defense against choking. It is a protective mechanism that prevents foreign materials from entering the throat, congesting the pharynx, larynx and trachea consequently mechanically obstructioning the flow of air from the environment into the lungs. Cardinal signs of a blocked airway include not being able to speak or cry out, turning blue in the face from lack of oxygen, desperately grabbing at one's throat, and coughing or labored breathing that produces a high-pitched sound. Following these symptoms, a person may fall unconscious. If oxygen is restricted for a long period of time permanent brain damage or death can result (13).
    People can train themselves to resist the gag reflex, for example as part of the act of sword swallowing but in most instances the absence of the gag reflex is a symptom of a number of severe medical conditions, such as damage to the glossopharyngeal nerve, or the vagus nerve (13).
    4. List and discuss strategies which can be implemented by a dental operator to alleviate symptoms in a gagging patient.
    Gagging can be caused by fear and anxiety and a feeling of not being incontrol. Establishing good communication with the patient and finding out what there dental fears and anxieties are, some people like to be talked through procedures others prefer not to know. As individuals have different thresholds at which they can stand stimulus towards the back of the mouth, dental opperators must implement different stratergies as even a simple dental examination can provoke violent rejection movements followed rapidly by retching an vomiting(8).
    Strategies include;
    1) Throat spray. Throat sprays, such as Vicks Ultra Cholaseptic Throat Spray, works by causing a numbing action towards the back of the throat, hence relieving the gag reflex (7).
    2) Desensitization methods. These methos include slowly desensitizing the patient towards the stimulus that causes the reflex response. This can include such things as giving a patient a mirror or impression try to take home to practise putting it in their mouth so as to get used to the feeling or doing a mandibular impression first so that the patient can become used to the feeling of what having an impression feels like (8).
    3) Relaxation methods. Things such as talking to the patient, telling them to breath through their nose and doing breathing excersises help in calming the patient down and distract them from what is going on in their mouth. Additionally, some patients 'feel' as though they are going to gag, so distracting them from what is happening in the mouth may help eg. alternate leg raising, which engages the stomach muscles and draws patient's attention away from procedure (15).
    4) Salt on the tip of the tongue. When salt is placed on the tip of the tongue, the nerves that trigger the gag reflex in the tongue become distracted/occupies (14).
    5) Ice on the tip of the tongue. When ice water is placed on the tip of the tongue, the nerves are again distracted from the site of the gag reflex as they become occupied at the site of the ice water.apparently (14).
    5) Patient-to-dentist communication. Communicatrion between the dental operator and the patient is important as this helps the operator to find out if the patient has a particularly active gag reflex or if there is a time of day where the patient is more prone to gag, and hence they will be able to formulate methods the alleviate the symptoms. The oparator can then be aware of the problem and is able to let the patient know that the procedure can be stopped at any stage if they are uncomfortable (14).
    6) Asking patient to focus upon something else. The dental operator can asking the patient to focus upon something else, such as lifting a foot up in the air or listening to music, as this can help to distract the patient from the procedure. Also, by lifting a leg into the air the abdominal muscles become engaged, and the diaphragm contracts and will reduce the change of the gag reflex ocuring (14).
    7) Another method is asking the patient to hum while the procedure is taking place. This could be while an impression is being taken or a rubber dam clamp is being placed. This is an effective method because it is known that an individual cannot hum and gag at the same time (14).
    8) Sitting rather than lying back and vice versa. Some patients may prefer to lie down in the dental chair at this will lay the soft palate and uvula backwards, hence preventing the gag reflex to take place. However, some patients prefer to be sitting upwards so that they can easily walk around or be in control of their reflex response that way. This is an issue of patient preference and the dental operator should communicate with the patient as to which method they prefer or find out which method works best for that patient (8).
    9) Providing treatment in small amounts. For some patients, the treatments is best offered at a slower rate. This is so that there is more time and extra caution can be placed upon each visit (8) (14).
    10) Sadation nitrous oxide (i.e. happy gas) is effective in almost eliminating the gag reflex. This method causes causes euphoria and slight hallucinations which distract the patient from what is happening in the oral cavity (11) (16).
    11) Using a nasal decongestant can help keep the nasal passageways open to promote breathing through nose (8).
    12) Accupuncture : accoring to new study published in the British dental journal stimulation of an accupunture point on the ear prior to undergoing treatment can effectively control and reduce the gag reflex (9).
    {gagging_2794_1_1_2964.jpg} 13)Electrolyte tablet can be taken intraorally a few minutes before the start of a procedure, which may help stop or suppress the gag reflex. It was assumed that by taking this tablet that alterations of the neural transmission of the vagus and hypoglossal nerves would alter or reduce the gag reflex. A repeated experiment found that tablets containing Sodium, chloride, bicarbonate, calcium and potassium was 97% effective (10).
    14) When the patient requires a local anesthetic for a procedure, this can be administered before taking a radiograph so that the site can be numb and the gag reflex will not take place (4).
    1.Barsby, MJ 1994, ‘The use of hypnosis in the management of ‘gagging’ and intolerance to dentures’, British Dental Journal, vol. 176, no. 3, pp. 97-102.
    2.Conny, DJ & Tedesco, LA 1983, ‘The gagging problem in prosthodontic treatment Part 11: Patient management’, The Journal of Prosthodontic Dentistry, vol. 49, no. 6, pp. 757-61.
    3.Dickinson, CM & Fiske, J 2006, ‘A review of gagging problems in dentistry: 2. Clinical assessment and management’, Journal of South African Dental Association, vol. 61, no. 6, pp. 258-62.
    4.Miles, D.A., Van Dis, M.L., Jensen, C.W. & Ferretti, A.B. (1999). Radiographic Imaging for Dental Auxiliaries. 3rd Edition. Saunders, Philadelphia.
    5.Ramsay, DS, Weinstein, P, Milgrom, P & Getz, T 1987, ‘Problematic gagging: principles of treatment’, Journal of American Dental Association, vol. 114, no. 2, pp. 178-83.
    6.Rosted, P, Bundgaard, M, Fiske J, Pedersen, AM 2006, ‘The use of acupuncture in controlling the gag reflex in patients requiring an upper alginate impression: an audit’, British Dental Journal, vol. 201, no. 11, pp. 721-5
    7.Wilkins, E. M. (2005). Clinical Pratice of the Dental Hygienist. 9th Edition. Lippincott Williams & Wilkins, Baltimore.

    (view changes)
    8:20 pm
  3. user_del NaomiJ NaomiJ left bohone
    8:17 pm
  4. user_del robyn3 robyn3 left bohone
    8:17 pm
  5. user_del AMY85 AMY85 left bohone
    8:16 pm
  6. user_del jenn26 jenn26 left bohone
    8:16 pm