Chapter 2 Concepts of Health and Disease By; Dr. Uche Amaefuna-Obasi (MD)

THERE ARE MORE TO LECTURES THAN SLIDES

Health The World Health Organization affirms that health is “more than the absence of disease,” but rather a state of “complete physical, mental, and social well-being,” This definition sets a lofty goal for patients seeking health as well as for health care professionals. The World Health Organization affirms that health is “more than the absence of disease,” but rather a state of “complete physical, mental, and social well-being,” This definition sets a lofty goal for patients seeking health as well as for health care professionals.

health….. Factor in health….. ▲ ▲ physical well-being ▲ ▲ mental well-being ▲ ▲ social well-being

Sub-Health Sub-Health There is a situation, in which the person dose not show specific symptoms and signs of disease, but lives a low-quality of life both physically and mentally. There is a situation, in which the person dose not show specific symptoms and signs of disease, but lives a low-quality of life both physically and mentally.

Manifestation of sub-health Manifestation of sub-health ▲ physical sub-health: fatigue & disability; hyponoia; gastralgia; heart-throb, etc. ▲ physical sub-health: fatigue & disability; hyponoia; gastralgia; heart-throb, etc. ▲ mental sub-health: angst; fidget; irascibility; insomnia, etc. ▲ mental sub-health: angst; fidget; irascibility; insomnia, etc. ▲ social sub-health: not concerned with our roles within society as a whole. ▲ social sub-health: not concerned with our roles within society as a whole.

angstirascibility

Disease Disease is referred as aberrant manifestation of deregulated homeostasis caused by harmful agents. Disease is referred as aberrant manifestation of deregulated homeostasis caused by harmful agents. Disease is defined as an abnormal life process which is induced by disorders of homeostasis under the action of certain cause(s). Disease is defined as an abnormal life process which is induced by disorders of homeostasis under the action of certain cause(s).

Factor in disease Factor in disease ▲ ▲ disease is caused by the etiological factors. ▲ ▲base of disease is deregulated homeostasis.

Etiology of Disease Etiology of Disease Concept of Etiological Factors & Predisposing Concept of Etiological Factors & Predisposing Etiologic factors involved in diseases include causative, predisposing and precipitating factors, which contributes to the onset of diseases.

Etiological factors Etiological factors ▲ ▲The factor that causes the disease and determine the clinical features of the disease. ▲ ▲Among the etiological factors, a wide range of extrinsic factors in the environment and intrinsic factors in the body must be considered.

Predisposing factors Predisposing factors The function of these factors is to intensify the effects of causative factors and promote the onset and development of diseases. Precipitating factor: Precipitating factor: The factors promotes the development of disease and influences the timing of illness onset. The factors promotes the development of disease and influences the timing of illness onset.

Risk factors Risk factors The risk factor concept is epistemological in nature: it is often not clear exactly what a risk factor contributes to understanding and explanation. The risk factor concept is epistemological in nature: it is often not clear exactly what a risk factor contributes to understanding and explanation.

Classification of etiological factors Classification of etiological factors Factors of environment ●Factors of environment ▲biological agents ▲biological agents ▲physical agents ▲physical agents ▲chemical agents ▲chemical agents Inherited factors ●Inherited factors ▲gene mutation ▲gene mutation ▲chromosomal aberration ▲chromosomal aberration

NOTE: NOTE: Genetic aberrancies may be caused by single or polygenic mutations. Genetic aberrancies may be caused by single or polygenic mutations. 【 genetic predisposition 】 【 genetic predisposition 】 The genetic mutations cause problems only when a person is exposed to certain environmental agents. The genetic mutations cause problems only when a person is exposed to certain environmental agents.

Congenital factors ● Congenital factors The disorders are of a developmental nature and most of them are non-genetic. The disorders are of a developmental nature and most of them are non-genetic.

Nutritional imbalance: Nutritional imbalance: Either excesses or deficiencies of nutrients predispose cells to injury. Either excesses or deficiencies of nutrients predispose cells to injury.

Immunological factors ● Immunological factors ▲ anaphylactic reaction ▲ anaphylactic reaction ▲ autoimmune disease ▲ autoimmune disease ▲ immunodeficiency disease ▲ immunodeficiency disease

Psychological and social factors ●Psychological and social factors Anxiety, strong or persistent psychological stimulation or stress may lead to mental illness and may be related to some diseases, such as hypertension, peptic ulcer, coronary heart disease, and depression. Anxiety, strong or persistent psychological stimulation or stress may lead to mental illness and may be related to some diseases, such as hypertension, peptic ulcer, coronary heart disease, and depression.

Pathogenesis Pathogenesis Pathogenesis of disease refers to the rules and mechanisms underlying the development or evolution of diseases. It studies how the primary pathological agents cause disease in organism and how the disease develops. Pathogenesis of disease refers to the rules and mechanisms underlying the development or evolution of diseases. It studies how the primary pathological agents cause disease in organism and how the disease develops.

Basic Mechanism of Disease Basic Mechanism of Disease Neural mechanism Neural mechanism Humoral mechanism Humoral mechanism Cellular mechanism Cellular mechanism Molecular mechanism Molecular mechanism

Neural mechanism ● Neural mechanism Neural system plays a central role in regulating entire life activities; therefore, the disorders in central nerve system will definitely affect the corresponding periphery system. Humoral mechanism ● Humoral mechanism Hormones Hormones Chemical mediators Chemical mediators Cytokines Cytokines

Cellular mechanism ●Cellular mechanism Molecular mechanism ● Molecular mechanism General Rules for Pathogenesis of Diseases General Rules for Pathogenesis of Diseases Damage and anti-damage responses ● Damage and anti-damage responses Damages are usually made when a variety of harmful insults attack the body. During this process, anti-damage responses are also induced in the body to restore the normal situation. Damages are usually made when a variety of harmful insults attack the body. During this process, anti-damage responses are also induced in the body to restore the normal situation.

Severe burn patient

Alternation of cause and result ● Alternation of cause and result In the evolution of a disease, the cause of the disease can produce a result, and this result can also become another cause in the evolution process of disease. In the evolution of a disease, the cause of the disease can produce a result, and this result can also become another cause in the evolution process of disease. ▲ benign circle ▲ benign circle ▲ vicious circle ▲ vicious circle

Local-systemic relationship ● Local-systemic relationship Diseases are generally systemic whereas the local pathological alterations caused by insults are recognized to be representative of systemic diseases Diseases are generally systemic whereas the local pathological alterations caused by insults are recognized to be representative of systemic diseases

Outcome of Disease Outcome of Disease The course of a disease varies. An acute disease has relatively sudden onset and lasts for a short term, whereas a chronic disease, sometimes begins with an acute phase, usually lasts for a long period of time. There are generally three types of outcomes for a disease. The course of a disease varies. An acute disease has relatively sudden onset and lasts for a short term, whereas a chronic disease, sometimes begins with an acute phase, usually lasts for a long period of time. There are generally three types of outcomes for a disease.

Outcome of disease include the following; 1. Complete recovery 2. Incomplete recovery 3. Death

This is best outcome of a disease. In this case, the pathologically altered metabolism, structure and function are perfectly restored, and the symptoms and signs of the disease disappear entirely. Complete recovery: This is best outcome of a disease. In this case, the pathologically altered metabolism, structure and function are perfectly restored, and the symptoms and signs of the disease disappear entirely. The main symptoms disappear but some pathological changes are left behind, namely sequela. Sequela is generally brought about by the compensatory response to maintain a relatively normal activity. Incomplete recovery: The main symptoms disappear but some pathological changes are left behind, namely sequela. Sequela is generally brought about by the compensatory response to maintain a relatively normal activity.

Death: The cessation of heart-beats and breath is used as the criterion of death of a body. Traditionally death ● Traditionally death ▲ agonal stage ▲ agonal stage ▲ stage of clinical death ▲ stage of clinical death ▲ stage of biological death ▲ stage of biological death

Brain death ● Brain death. The functions of cerebrum and brain stem stop forever.

● Criteria for brain death ▲irreversible coma. ▲cessation of spontaneous respiration. ▲norpurposeful movement. ▲absence of cephalic reflexes. ▲absence of any electric activity of the brain. ▲absence of cerebral circulation

Human Vegetable: When cerebral function is lost, the reticular activating system and brain stem can maintain a crude waking state known as a vegetative state. Human Vegetable: When cerebral function is lost, the reticular activating system and brain stem can maintain a crude waking state known as a vegetative state.