• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

The Digestive System.

Extracts from this document...

Introduction

THE DIGESTIVE SYSTEM The digestive system is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. Inside this tube is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food. Two solid organs, the liver and the pancreas, produce digestive juices that reach the intestine through small tubes. In addition, parts of other organ systems (for instance, nerves and blood) play a major role in the digestive system. LIVER The liver is such an important organ in the human body that without it we'd only survive for 24 hours, and it's one of the few organs that has the power to regenerate when it gets damaged. ...read more.

Middle

It plays a dual role in helping us get the most out of food. The pancreas produces many of the digestive enzymes that we need, which are poured into the small intestine. It also produces bicarbonate (NaHCO3), which neutralizes the acid that comes from the stomach. Stomach acid is so strong that without the neutralizing effects of the bicarbonate it would destroy the digestive enzymes produced by the pancreas. The pancreas is an important member of the endocrine system, the body's mechanism for making hormones, which are then circulated around the body by the blood. The first hormone that it makes is called insulin, and its job is to help cells take up the sugar (glucose) which they need for energy. But if too much glucose is taken from the blood, a second hormone is released, called glucagons, which converts sugar stored in the liver (called glycogen), into glucose. ...read more.

Conclusion

As well as acting as a temporary storage facility, the stomach also continues the digestive process that begun in the mouth. The stomach produces enzymes that break down proteins in the food. Hydrochloric acid is also produced by the stomach, to activate the enzymes that break down the proteins. When the nerves in the stomach wall sense that the stomach has become stretched with food, the muscles of the stomach begin to work so that the food and enzymes mix together. This ensures that the first stage of digestion is completed before food moves on to the small intestine where the majority of digestion takes place. The stomach protects itself from being digested by its own enzymes, or attacked by the corrosive hydrochloric acid, by secreting a sticky neutralising mucus that clings to the stomach walls. However, if this layer becomes damaged in anyway it can result in painful and unpleasant stomach ulcers. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Exchange, Transport & Reproduction section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Exchange, Transport & Reproduction essays

  1. Marked by a teacher

    Human Reproductive System

    4 star(s)

    Endometrium The endometrium is the membrane lining the uterus. It prevents friction between the opposed walls of the myometrium, thereby maintaining the patency of the uterine cavity. During menstrual cycle or estrous cycle, it grows to a thick, blood vessel rich, glandular tissue layer which provides an optimal environment for the implantation of a blastocyst upon arrival in the uterus.

  2. Marked by a teacher

    What is Type 1 diabetes

    3 star(s)

    Remember that ketone-measuring urine strips go out of date very quickly, so they will not always detect ketone bodies even if they are present. If you do detect them in your urine, and your blood glucose levels are also high, contact your doctor for help and instructions.

  1. The Endocrine System

    In contrast, other glands including sweat glands, salivary glands, and glands of the gastrointestinal system secrete the substances they produce through ducts, and those substances are used in the vicinity of the gland. The regulation of body functions by the endocrine system depends on the existence of specific receptor cells

  2. The Skeletal and Muscular System

    Scoliosis. The side to side curvature of the vertebral column. The spine bends either to the left or to the right. It is more common in women than men and mostly occurs at the start of adolescence. Normally scoliosis is not a serious condition but if left untreated the

  1. Blood System Assignemnt

    Like arteries, veins have three layers: an outer layer of tissue, muscle in the middle, and a smooth inner layer of epithelial cells. However, the layers are thinner, containing less tissue. Veins receive blood from the capillaries after the exchange of oxygen and carbon dioxide has taken place.

  2. Urinary system

    The middle layer, the muscularis, is composed of smooth muscle, which allows a peristaltic contraction to take place enabling urine to be passed into the bladder. 3) Outer layer is the adventitia that is made of areolar connective tissue containing the blood vessels, lymphatic vessels and nerves. (Vander, A. 1995)

  1. the role of the microbiology department

    Wording of reports The aim of the clinical microbiologist is to provide clinicians and health officers with reports that are understandable, instructive and relevant as well as reliable. The laboratory should therefore have a carefully considered policy for the wording of reports and all staff should adhere to that policy.

  2. The Endocrine System.

    Negative feedback regulates the secretion of almost every hormone. Cycles of secretion maintain physiological and homeostatic control. These cycles can range from hours to months in duration. Figure 3 shows an example of negative feedback in the thyroxine release reflex. Figure 3 The liver acts as a storehouse for glycogen, the storage form of glucose.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work