Larynx

The larynx or voice box, is a muscular tube in the throat of all mammals and some reptile and amphibians. It contains the vocal cords, which produced sound that is converted into speech and other utterances by the lips, teeth, and tongue. Birds do not have a larynx , but most have a modified portion of the wind pipe called the syrinx with which they vocalize.

The larynx has several segments of firm, elastic cartilage held together by muscle and ligament. The largest segment, the thyroid cartilage, consists of two plates that form a ridge, called the “Adam’s Apple.” The larynx extend from the pharynx (throat) above the tracheae (windpipe) below.

In mammals, including humans, the larynx has a flap-like structure, the epiglottis, at its inlet. The epiglottis caused swallowed food to pass from the throat into the esophagus rather than into the tracheae.

The vocal cords, located in the upper region of the larynx, are two muscularized fold of mucous membrane that extend from the larynx wall. The gap between the fold is the glottis. Each fold encloses an elastic vocal ligament and muscle, which controls the tension and rate of vibration of the cords as air passes through them. In normal breathing the vocal muscles are held slack, allowing air to pass in and out of a wide slit. The tighter the vocal muscle contract the vocal cords, the higher the tone the sound produced.

Cancer or other growth sometimes necessitate removal of the larynx, an operation known as a larynxgectomy. After such an operation a patient usually breathes through a surgically formed opening in the neck. The patient may be taught to use gullet tissue to produce sounds that are then modified by the mouth structure to yield recognizable speech.

Pancreas

A long, thin organ in humans, the pancreas has both digestive and endocrine functions and for this reason contains two completely different types of cells. Measuring about 12- 15 cm (5-6 in) long, it is nested within the curve of the duodenum and hind the stomach, in front of the spine and aorta.

The digestive, or exocrine, cells of the pancreas consist of a number of organ, small lobules, or acinar cells, joined together into small ducts that, in turn, joint the two major ducts of Santorini and Wirsung, which empty through small muscular opening into the duodenum. The lobules contain numerous cells that secrete pancreatic secretion containing electrolytes and three important digestive enzymes, typsin, amylase, and lipase. The enzyme digest protein, spilt fat, break down highly polymerized nucleic acid, and break down polysaccharides such as starch, amylopectin, and glycogen. The protein splitting enzyme typsin becomes active only when the duodenal enzyme enterokinase is mixed with it, or in the present of diseases such as pancreatitis or cancer. In a similar manner the activity of the other enzymes is enhanced by the admixture of intestinal secretions and bile.

The endocrine function of the pancreas is to release hormone secreted by small groups of cells called the islets of Langerhans into the blood. The hormone pancreozymin and gastrin, as well as the vagus nerve, control the amount enzyme secreted. The islets of the Langerhands secrete two hormone that regulate carbohydrate metablolism. Insulin causes a decreases blood sugar. Other hormone control intestinal motilily or interact with the thyroid islet cells a person develops Diabetes Mellitus.

Nose

The nose, the site of the sense of smell is the organ through which mammals take in air. It is supported by cartilage and bone, covered with skin, lined with a mucous membrane, and provided with muscle. A nasal septum divides it into passages, each of which begins with a vestibule and contains a respiratory and olfactory region. The lining of the vestibule is continuous with the skin and contains hairs, sweat glands, and sebaceous (oil producing) glands.

The respiratory region includes nearly all of the septum and the lateral walls of the nose. Goblet cells, which produce and secrete a watery mucus, are present in the lining, as is a type of erective tissue, composed of large, thin-walled veins whose blood supply serves to warm incoming air. The olfactory region is located on the superior concha and adjacent septum. Olfactory cells are present in its lining and have delicate, slender process (modified cilia) at their free surface. Odors from chemicals in the air are received by these processes. Nerve cells that impinge upon the olfactory cell convert the chemical information into nerve impulse and convey the sensory information to the brain.

The nose is divided by the septum into two cavities, each containing three called cnchae and lined with a mucous membrane. Air taken in through the nostrils is filtered by the cilia small hairs in the mucous membrane, mostened by the mucus, and warmed by the blood vessels of the superior conchae and adjacent part of the septum, contains olfactory cells, nerve cells sensitive to odors. Airborne chemicals interact with the ciliated endings of these cells; nerve impulses then are carried by the olfactory nerve to the brain.