Nausea and Vomiting

Introduction to nausea and vomiting

Nausea and vomiting are symptoms of an underlying disease and not a specific illness. Nausea is the sensation that the stomach wants to empty itself, while vomiting (emesis) or throwing up, is the act of forcible emptying of the stomach.
Vomiting is a violent act in which the stomach has to overcome the pressures that are normally in place to keep food and secretions within the stomach. The stomach almost turns itself inside out - forcing itself into the lower portion of the esophagus (the tube that connects the mouth to the stomach) during a vomiting episode.

What causes nausea or vomiting?

There are numerous causes of nausea and vomiting. These symptoms may be due to the following:

• acute gastritis
  
• central causes (signals from the brain)
  
• association with other illnesses remote from the stomach
  
• medications and medical treatments
  
• mechanical obstruction of the bowel

Acute gastritis

Acute gastritis (gastro=stomach + it is= inflammation) is often caused by an offending agent which irritates the lining of the stomach. Examples of these include:

• Infections: Infections are often the cause, whether it is a common virus or an infection that is contracted from travel. There may be associated crampy upper abdominal pain, fever ,and chills may be present. Common viral infections include noroviruses and rotavirus. Parasitic infections often are associated with diarrhea but may also have a component of nausea and vomiting. Infection by bacteria in the Helicobacter family (like H. Pylori) can also be the infectious agent.
  
• Stomach flu: Stomach flu is a non-specific term used to describe vomiting and diarrhea associated with a viral infection. It should not be confused with influenza, whose symptoms include fever, chills, cough, and myalgias (muscle pain).
  
• Food poisoning: Food poisoning may cause significant vomiting and usually is caused by a bacterial toxin. Symptoms begin within a couple hours of eating contaminated or poorly prepared food and may last for 1-2 days. Sources of food poisoning include Salmonella, Campylobacter, Shigella, E. coli, Listeria, or Clostridium botulinum (botulism).
  
• Other stomach irritants: alcohol, smoking, and non steroidal anti-inflammatory medications such as aspirin and ibuprofen may irritate the stomach lining.
  
• Peptic ulcer disease: Peptic ulcer disease can range from mild irritation of the stomach lining to the formation of a defect in the protective lining of the stomach called an ulcer.
  
• Gastroesophageal reflux disease (GERD, reflux esophagitis): Nausea or vomiting is also associated with irritation of the lining of the esophagus 

Smoker's Lung Pathology Photo Essay

Smokers lung introduction

Cigarette smoking is associated with a wide variety of abnormalities throughout the body that cause not only illness, but also, all too often, death. Indeed, if all deaths from diseases related to smoking (lung disease, heart disease, and cancers of many different organs) were considered, a case could be made for cigarette smoking as the leading cause of death in industrialized countries. Ironically, it is also the most preventable cause of death in our society!
This photo essay will focus on smoker's lung. The term "smoker's lung" refers to the structural and functional abnormalities (diseases) in the lung caused by cigarette smoking. First, the normal structure and function of the lung will be described and illustrated. Then, the structural and functional abnormalities caused by smoking will be described and illustrated.

What is the structure of the normal lung?

We have a right lung and a left lung that reside in the chest cavity and surround the heart. A thin membrane called the pleura covers the outer surface of the lung. The air we breathe gets into the lung through an airway (path for air). Figure 1 is a diagram showing the main parts of the airway and lung.

Figure 1: NORMAL AIRWAY AND LUNG

The airway consists of the oral and nasal cavities, which connect to the voice box (larynx), which connects to the windpipe (trachea). Note in the diagram that the windpipe splits into two air passages called bronchi, one going to each lung (right and left main bronchi). The trachea and larger bronchi contain C-shaped rigid bars of cartilage in their walls. The cartilage helps to keep the airway from collapsing when there is negative pressure in the airway, as occurs when we breathe in (inhale or inspire). The right lung has three separate sections (upper, middle, and lower lobes), while the left lung has just an upper and a lower lobe. Each lobe has its own bronchi and blood supply.
Further along in the airway, within the lung, the bronchi continue to divide into ever-smaller (narrower) tubes, much like the branches of a tree. (Hence, the term tracheobronchial tree.) The walls of the bronchi contain muscles that can cause the airway to expand (widen) or contract (narrow). For example, during exercise, the airway expands to increase airflow (ventilation). Conversely, when exposed to polluted or very cold air, the airway contracts to protect the downstream tissues from injury. The smaller branches of the bronchial tree, called bronchioles, also contain muscle, but they lack cartilage. Notice in Figure 1 that the very smallest bronchioles (respiratory bronchioles) connect directly to tiny air sacs in the lung, called alveoli. Figure 2 shows a microscopic section of a normal bronchial wall.

Figure 2: NORMAL BRONCHIAL WALL

In this picture, you can see that the bronchial wall contains cartilage and muscle, as described above. Also, note that different types of cells make up the lining (epithelium) of the bronchi (as well as of the trachea and bronchioles). One type of cell is called a goblet cell because of its shape. The goblet cells produce mucus, which lubricates the airways and traps inhaled foreign material (e.g., bacteria, viruses, and pollutants). Other cells in the epithelium are called ciliated cells, which are discussed in the next paragraph. Beneath the surface of the airway, the goblet cells and other epithelial cells are clustered into structures called bronchial glands. These glands secrete additional mucus and other lubricating fluids.
Inflammatory cells are also in the normal bronchial wall. Look again at Figure 2 and observe that they are scattered beneath the lining of the airway. These inflammatory cells, also known as white blood cells, include neutrophils, lymphocytes, and macrophages. Their job (in this situation) is to destroy and/or engulf any inhaled foreign material that becomes trapped in the mucus. In doing so, however, inflammatory cells create debris. To help dispose of the debris, most of the cells that line the airway have hair-like processes called cilia. These ciliated cells sweep and push the foreign material and debris up into the larger airways where they can be coughed up or spit out.
The lung resembles a sponge and is composed of millions of alveoli. This structure provides a huge surface for gas exchange that has been estimated to be equal to the size of a tennis court. (These tiny air sacs can be seen with a magnifying glass.) Figure 3 is a microscopic section of a normal lung, showing the alveoli.

Figure 3: NORMAL LUNG ALVEOLI

The wall (alveolar septum) of each alveolus contains a very small blood vessel called a capillary. Blood flows slowly through each capillary to allow time for the lung to perform its main function, which is the exchange of gas (oxygen and carbon dioxide). The actual site for gas exchange is pictured in the high magnification section on the right side of figure 3. Thus, the capillary blood picks up oxygen (O2) from the inhaled air in the alveoli. At the same time, the capillary blood releases the body's waste gases, most importantly carbon dioxide (CO2), into the alveoli. (Waste gases are by-products of the body's metabolism.)

Encephalitis and Meningitis

Encephalitis and meningitis facts

• Encephalitis is an inflammation of the brain.
• Meningitis is an inflammation of the membranes (called meninges) that surround the brain and spinal cord.
• Anyone experiencing symptoms of encephalitis or meningitis should see a doctor immediately.

What is encephalitis?

Encephalitis is an inflammation of the brain. There are many types of encephalitis, most of which are caused by infections. Most often these infections are caused by viruses. In addition to infections, encephalitis can also be caused by certain diseases that result in an inflammation of the brain.

What are encephalitis symptoms and signs?

The signs and symptoms of encephalitis can range from very mild symptoms to potentially life-threatening. Signs and symptoms of encephalitis include sudden fever, headache, vomiting, visual sensitivity to light, stiff neck and back, confusion, drowsiness, unsteady gait, and irritability. Loss of consciousness, poor responsiveness, seizures, muscle weakness, sudden severe dementia and memory loss can also be found in patients with encephalitis.
Anyone experiencing symptoms of encephalitis should see a doctor immediately.

What is meningitis?

Meningitis is an inflammation of the membranes (called meninges) that surround the brain and spinal cord. Meningitis may be caused by many different viruses and bacteria. It can also be caused by diseases that can trigger inflammation of tissues of the body without infection (such as systemic lupus erythematosus and Behcet's disease).