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Every living thing, both plants and animals, can succumb to disease. People, for example,are often infected by tiny bacteria. Hundreds of different diseases exist. Each has its own specific diagnosis and treatment. Each is caused by its specific pathogenic microorganism.In this part, you will have an overview of the diseases of the human body.
☆ Understand the basic concepts about human disease.
☆ Describe the classifications of diseases.
☆ Describe the principles of diagnosis.
☆ List the diagnostic tests and procedures.
A disease associated with structural changes is called an organic disease. In contrast,a functional disease is one in which no morphologic abnormalities can be identified even though body functions may be profoundly disturbed.
Pathology is the study of disease and a pathologist is a physician who specializes in diagnosing and classifying diseases, primarily by examining the morphology of cells and tissues. A clinician is any physician or other health practitioner who cares for patients.
A disease may cause various subjective manifestations, such as weakness or pain, in an affected individual: These are called symptoms. A disease may also produce objective manifestations, detectable by the clinician, which are called signs or physical findings.
A disease that causes the affected individual no discomfort or disability is called an asymptomatic disease or illness. The distinction between asymptomatic and symptomatic disease is one of degree, depending primarily on the extent of the disease.
The term etiology means cause. If the cause of a disease is known, the agent responsible is called the etiologic agent. The term pathogenesis refers to the manner by which a disease develops, and a pathogen is any microorganism, such as a bacterium or virus, that can cause disease.
Diseases tend to fall into several large categories, although the diseases in a specific category are not necessarily closely related. Rather, the lesions produced by the various diseases in a category are morphologically similar or have a similar pathogenesis. Diseases are conveniently classified in the following large groups: congenital and hereditary diseases; inflammatory diseases; degenerative diseases; metabolic diseases and neoplastic diseases.
Congenital and hereditary diseases are the result of developmental disturbances. They may be caused by genetic abnormalities, abnormalities in the numbers and distribution of chromosomes, intrauterine injury as a result of various agents, or interaction of genetic and environmental factors.
Inflammatory diseases are those in which the body reacts to an injurious agent by means of inflammation. Some diseases in this category appear to be caused by antibodies formed against the patient’s own tissues, as occurs in some uncommon diseases classified as autoimmune diseases.
In degenerative diseases, the primary abnormality is degeneration of various parts of the body. In some cases, this may be a manifestation of the aging process. In many cases,however, the degenerative lesions are more advanced or occur sooner than would be expected if they were age related, and they are distinctly abnormal.
The chief abnormality seen in metabolic diseases is a disturbance in some important metabolic process in the body.
Neoplastic diseases are characterized by abnormal cell growth that leads to the formation of various types of benign and malignant tumors.
The determination of the nature and cause of a patient’s illness by a physician or other health practitioner is called a diagnosis. It is based on the practitioner’s evaluation of the patient’s subjective symptoms, the physical findings, and the results of various laboratory tests, together with other appropriate diagnostic procedures. When the practitioner has reached a diagnosis, he or she can then offer a prognosis; an opinion concerning the eventual outcome of the disease. Then, a course of treatment is instituted.
The clinical history is a very important part of the evaluation. It consists of several parts:the history of the patient’s current illness; the past medical history; the family history; the social history and the review of systems.
The history of the present illness elicits details concerning the severity, time of onset, and character of the patient’s symptom. The past medical history provides details of the patient’s general health and previous illnesses. The family history provides information about the health of the patient’s parents and other family members. The social history deals with the patient’s occupation, habits, alcohol and tobacco consumption, and similar data. The review of systems inquires as to the presence of symptoms other than discloses in the history of the present illness; such symptoms might suggest disease affecting other parts of the body.
The physical examination is a systematic examination of the patient. Any abnormalities detects on the physical examination are correlated with the clinical history. At this point,the practitioner begins to consider the various diseases or conditions that would fit with the clinical findings. Sometimes, more than one possible diagnosis needs to be considered.
Diagnostic tests and procedures fall into two classifications: invasive procedures and noninvasive procedures. Invasive procedures are so-named because the patient’s body is actually “invaded” in some way in order to obtain diagnostic information. Noninvasive procedures are those that entail no risk or minimal risk or discomfort to the patient.Diagnostic tests and procedures can be classified into the following major categories.
Clinical laboratory tests can be used to determine the concentration of various constituents in the blood and urine, which are frequently altered by disease. Clinical laboratory tests are also used to evaluate the functions of organs such as clearance tests,pulmonary function tests, liver function tests, microbiologic tests and serologic tests.
Several different tests measure the electrical impulses associated with various bodily functions and activities. These include the electrocardiogram (ECG), the electroencephalogram (EEG), and the electromyogram (EMG). The most widely used of these tests is the electrocardiogram.
The function of various organs can be evaluated by administering a substance labeled with a radioactive material called radioisotope. One may administer a radioactive material that is filtered out or concentrated in a tissue or organ and then measure the radioactivity by radiation detectors.
An endoscopy is an examination of the interior of the body by means of various types of rigid or flexible tubular instruments. These instruments have a system of lenses for viewing and a light source to illuminate the region being examined.
Ultrasound is a technique for mapping the echoes produced by high-frequency sound waves transmitted into the body. Echoes are reflected wherever there is a change in the density of the tissue. The reflected waves are recorded on sensitive detectors, and images are produced.
Figure 2-1 Ultrasonic picture
X-rays are passed through the part of the body to be examined, and the rays leaving the body expose an X-ray film. The extent to which the rays are absorbed by the tissues as they pass through the body depends on the density of the tissues. The X-ray image produced on the film is called radiograph or roentgenogram .
Abnormalities of internal organs that cannot be identified by means of standard X-ray examinations can often be discovered with computed tomographic scan (CT scan), which is performed by a highly sophisticated X-ray machine that produces images of the body in cross section.
Figure 2-2 CT scan machine
Figure 2-3 MRI machine
Magnetic resonance imaging (MRI) produces computer-constructed images of various organs and tissues somewhat like CT scans. MRI scans depend on the response of hydrogen protons contained within water molecules when they are placed in a strong magnetic field.
Related to radioisotope studies but much more complex and sophisticated is one of the newest of the diagnostic imaging tests called positron emission tomography (PET), or simply PET scans. One uses PET scans to study body functions by injecting into the subject a biochemical compound and then assessing the distribution and metabolism of the compound.
Abnormal cells can often be identified in the fluids or secretions that come in contract with the epithelial surface. It is often possible to determine the cause of a patient’s disease by histologic examination of a small sample of tissue removed from the affected tissue or organ.This procedure is called a biopsy .
There are two different types of treatment: specific treatment and symptomatic treatment.A specific treatment is one that exerts a highly specific and favorable effect on the basic cause of the diseases. Symptomatic treatment, as the name implies, makes the patient more comfortable by alleviating symptoms but does not influence the course of the underlying disease.
asymptomatic [ˌeɪsɪmptəˈmætɪk] having no symptoms
biopsy [ˈbaɪɒpsi] removal and pathologic examination of specimens in the form of small pieces of tissue from the living body
congenital [kənˈdʒenɪtl] existing at or from your birth
elicit [iˈlɪsɪt] to get information from someone by asking questions
endoscopy [enˈdɒskəpi] procedures of applying endoscopes for disease diagnosis and treatment, which involves passing an optical instrument along either natural body pathways such as the digestive tract, or through keyhole incisions to examine the interior parts of the body
etiology [ˌi:tɪˈɒlədʒɪ] cause of a disease
hereditary [hɪˈredɪtri] able to be passed down from parent to child
intrauterine [ˌɪntrəˈju:tərɪn] within or situated in the uterus
morphology [mɔ:ˈfɒlədʒi] the branch of biology that deals with the form and structure of organisms without consideration of function
neoplastic [ˌni:əʊˈplæstɪk] about tumor
organic [ɔ:ˈgænɪk] produced by or found in animals or plants
pathogenesis [ˌpæθəˈdʒenɪsɪs] the mechanism by which the disease is caused; the origin and development of the disease
proton [ˈprəʊtɒn] a very small piece of matter present in the central part of an atom
radioisotope [ˌreɪdɪəʊˈaɪsətəʊp] a radioactive isotope
radionuclide [ˌreɪdɪəʊˈnju:klaɪd] a radioactive nuclide
roentgengram [ˈrentgəngræm] an X-ray photograph
Directions: Select the letter of the choice that best completes the statement or answers the question .
(1) Various subjective manifestations, such as weakness or pain, in an affected individual can be called___.
A. signs B. symptoms C. physical findings D. diagnosis
(2) The term___refers to the manner by which a disease develops.
A. pathogenesis B. pathogen C. pathology D. pathologist
(3) Some degenerative lesions are___-related, and they are often normal.
A. gender B. time C. gene D. age
(4) Malignant tumors can be termed as___.
A. fibroma B. benign tumor C. cancer D. sarcoma
(5) A prognosis is a prediction about the___of the disease.
A. findings B. outcome C. treatment D. surgery
(6) The history of the___illness talks about the severity, time of onset, and character of the patient’s symptom.
A. present B. past C. family D. social
(7) Which of the following item is NOT related to patient’s social history?
A. Occupation.B. Habits.
C. Alcohol and tobacco consumption.D. Health status of family members.
(8)___procedures entail no risk or minimal risk or discomfort to the patient.
A. Noninvasive B. Invasive C. Diagnostic D. Clinical
(9) Which of the following CANNOT measure the electrical activity of the body?
A. ECG.B. EMG.C. MRI.D. EEG.
(10) The extent to which the X-rays are absorbed by the tissues as they pass through the body depends on the___of the tissues.
A. altitude B. degree C. shape D. density
Directions: Label the procedures on the following pictures .
Directions: Give some examples of the following terms.You may refer to the text above or search from Internet .
Directions: Match each of the following terms in Column A with its definition in Column B .
