Fundamentals of Medicine, Causes of Disease - Health and Medicine, General Science UPSC Notes | EduRev

Etiology : Etiology is the study of causation of disease. It may be intrinsic (within the body) or extrinsic (outside the body).

Pathology : Pathology deals with the study of diseases and their causes.

Homeostasis : The mechanism by which the body i s kept in equilibrium is known as Homeostasis.

Predisposing Causes : are those that make the person susceptible to the disease and are also known as remote, distant or preparatory causes.

Pathogenesis : The mechanism by which the causes produce disease.

Symptoms or Signs is the outward manifestations of the patient suffering from disease while alive.

Lesion is the alteration in the structure, detectable macroscopically by naked eye or microscopically. 
Incubation period is the time that elapses between the action of a cause and manifestation of disease. 
Prognosis is the estimation of probable severity and outcome of disease. Morbi dity is the percentage of deaths among population affected by a disease. Autopsy is seeing with one's own eyes. Also known as necropsy. 
Biopsy is examination of tissues received from living body.

Causes of Disease

Etiological Factors

The disease causing agents can be classified as follows :

1. Genetic or Inher ited causes : These causes are transmitted to the offspring through the grermplasm.

(a) Lethal factors : Some factors cause death in utero or after birth death

(b) Sub lethal factors : Those factors whi ch are inherited and interfere with the function of the body but do not cause death.

(c) Defects that are inherited errors in structure or function

Crytorchidism : The condition in which one or both testicle do not descend to the scrotal sac and remain in abdominal cavity. The testicle is complete or partialy non functional in this condition.

Webbed digits Web lik e str uctur es ar e pr esent in between the digits

II. Non-genetic or Non inherited defects : These causes do not transmitted through the germ plasm.

(a) Anomalies : Developmental defect affecting an organ or part of the body.

1. Disturbances in development

Arrest of development

(i) Agenesia or aphasia : Compl et e abse nc e of a body part. Agenesia renale—when there is no Kidney in the body.

(ii) Hypoplasia : Reduction in size of a body part.

(iii) atresia : Clos er of the lumen of a hol low orga n or duct - Atresia ani (closure of ana opening)

(iv) Fissure : Inability to fuse the part on median line.

(v) Fusion of paired organs : Horse shoe kidney.

Excessive development

(i) Congenital hypertrophy : Increase in the size of the organ. Example : Ventricular hypertrophy is the hypertrophy of the myocardium of the ventricle.

(ii) Increase in number - Example: Polydactyla is the presence of supernumerary digits on the hands or feet.