Biology in Focus, HSC Course Glenda Childrawi, Margaret Robson and Stephanie Hollis A Search For Better Health Topic 1: What is Health

DOT Point(s) discuss the difficulties of defining the terms ‘health’ and ‘disease’ outline how the function of genes, mitosis, cell differentiation and specialisation assist in the maintenance of health use available evidence to analyse the links between gene expression and maintenance and repair of body tissues world.edu

Introduction Since the beginnings of recorded history, humans have shown great interest in the state of their health and have recognised that living things do not always function properly. The presence of ‘symptoms’ is a clear indication that all is not well with the animal or plant.

Introduction Over time, many different approaches to the treatment and management of these symptoms have been implemented, and as technology has developed, these approaches have changed in order to help maintain the health of an organism.

Health and Disease Health is more than merely the absence of disease. Health is defined by the World Health Organization (WHO) as: Health: a state of complete physical, mental and social well- being, and not merely the absence of disease or infirmity. thesecreasesdaily.blogspot.com

Health and Disease This definition allows the ‘whole’ person to be taken into account rather than just whether they have a disease or not. An individual who does not have a disease may still not be considered healthy. On the other hand, an individual who suffers from a disease could still be classed as healthy. slowbuddy.com

Health and Disease Physical health refers to the physical state of the body and includes such things as our level of fitness, body weight, amount of energy and the proper functioning of the systems in the body. healthybodylife.com

Health and Disease Mental health is related to our ability to function effectively in society and to cope with changing situations in our lives. Social health is our ability to interact, communicate and socialise effectively.

Health and Disease One problem with the WHO definition of health is that it is very broad, and if taken literally it would be very difficult to achieve a healthy status. It would be very unlikely that a person has a ‘complete’ state of physical, mental and social wellbeing at any one time.

Health and Disease The concept of health for individuals is very subjective and depends on their life’s circumstances. What is healthy for one may not be regarded as healthy for another. Different individuals have different ideas about what is considered an appropriate level of physical, social and mental health.

Health and Disease A person who is physically fit and not suffering from any disease would consider themselves to be healthy whereas a person who has a disability or a chronic disease, may describe themselves as healthy because they have learnt to adapt and cope with this disability or disease in their everyday life. Health is a constantly changing state and is relative to others and ourselves over a period of time. -

Health and Disease Disease can be defined in many ways, but one of the most common is: Disease: any condition that adversely affects the normal functioning of any part of a living thing.

Health and Disease A problem with most definitions of disease is that they are quite broad and imprecise. Conditions that would not normally be classed as diseases could be, if the above definition of disease were to be taken literally. It could mean that a broken arm would be classed as a disease because it adversely affects the normal functioning of the body. Similarly, pregnancy could also be considered to be a disease.

Health and Disease The ‘normal functioning’ referred to in the definition may be at different levels for different individuals. For example, absent-mindedness in the elderly may be a normal facet of aging whereas it could be a manifestation of a disease in the young. umanitoba.ca

Maintenance of Health The function of genes, mitosis, cell differentiation and specialisation assist in the maintenance of health.

Maintenance of Health Differentiation: cells mature and take on different structural features, so that they become structurally suited to perform a specific function in the body. Specialisation: specific genes are ‘switched on’ in order to perform a particular function in the body.

Maintenance of Health For example, nerve cells (pictured here) have a particular structure, and specific genes ‘switched on’ that allow the transfer of electrochemical messages. Macrophages are cells that carry out the specific function of phagocytosis to help the body fight disease.

Maintenance of Health Differentiation and specialisation enable cells to work together in a healthy body to carry out complex functions in a controlled and co-ordinated way in order to maintain and repair tissues.

Maintenance of Health The function of genes and mitosis The maintenance of health is dependent on the information stored in the DNA of each cell. Remember: A gene is a hereditary unit that controls the production of polypeptides that make up the proteins in the cell. science.howstuffworks.com

Maintenance of Health These proteins are responsible for normal cell functioning, growth and repair. A malfunction in a particular gene may result in the inability of the cells to function properly and lead to the onset of disease. For example, cystic fibrosis is a genetic disease that is caused by a mutation to the CFTR gene.

Maintenance of Health The information contained in genes also prescribes how and when an organism’s body tissues are maintained and repaired, so that any malfunction in these genes will be detrimental to healthy cells. questgarden.com

Maintenance of Health Mitosis is the process of cell division by which identical body cells are produced to allow for: growth repair of damaged tissue, replacement of worn out cells, and genetic stability in which there is a precise and equal distribution of chromosomes to each daughter nucleus, so that all resulting cells contain the same number and kind of chromosomes as each other and the parent cell.

Maintenance of Health Mitosis allows all cells to function normally and tissues in the body to be repaired and maintained. If cells are damaged through injury or disease, they are replaced by the division of healthy cells close to the injury or disease site.

Maintenance of Health Genes code for the proteins that are responsible for the regulation of the cell cycle and mitosis in healthy cells. The types of genes responsible for the regulation of the cell cycle and mitosis are: DNA repair genes Proto-oncogenes Tumour suppressor genes nigamanths.blogspot.com

Maintenance of Health DNA repair genes: these code for proteins that are responsible for the stopping of the cell cycle while other proteins remove the damaged regions of DNA and replace them with a new correct sequence.

Maintenance of Health If these genes mutate they will no longer function correctly, the DNA is not repaired, and the damaged DNA is replicated. As a result the correct proteins/enzymes necessary for normal cell functioning, growth and repair will not be produced and disease will occur. medimoon.com

Maintenance of Health Proto-oncogenes: these code for proteins that stimulate cell growth and mitosis. aiss-biology-11.wikispaces.com

Maintenance of Health Tumour suppressor genes: these code for proteins that slow down or stop cell growth and mitosis. These genes also code for proteins that induce cell death if there is an uncontrolled increase in cell numbers. scitechdaily.com

Maintenance of Health In a healthy cell, these genes tightly regulate cell growth and mitosis. If these genes are damaged or mutated, this regulation is disrupted. spotonlists.com

Maintenance of Health Mutations to proto-oncogenes lead to the expression of oncogenes that would normally be ‘silent’. This causes uncontrolled production of cells and prevents cell death. Mutations to tumour suppressor genes halt the production of proteins that control cell division and cell death.

Maintenance of Health This disruption of the normally regulated cell cycle leads to uncontrolled cell replication which: does not allow cells to differentiate, so they cannot perform the specialised functions necessary for normal body functioning causes the formation of tumours. If the tumour spreads to other tissues, cancer results.

Maintenance of Health In some cases, mutations to certain genes could cause uncontrolled cell death, which leads to degenerative conditions such as Alzheimer’s disease. biol blogspot.com

Homework -Students to complete Maintenance and repair of body tissue