Unit 12: Diseases and Infection
Learning aim A: Investigate different types of diseases and infections that can affect humans
Introduction:
To help me develop a better understanding of the field I will pursue later which will be either
Pharmacy, Physiotherapy or nursing, I will need to secure a place at my local hospital which
is currently offering clinical insight work experience. This will enhance my skills and will
help me determine my following steps from key stage 5 studies.
Henceforth, as an applicant I am required to produce two separate case studies regarding
disease processes involved in infectious and non - infectious diseases.
‘The four non - pathogenic diseases’
Non – infectious diseases
What is a non – infectious disease?
A non - infectious disease is a type of disease which is not contagious (cannot be spread)
from one person to another. This is because there is no vector (a living organism that
transmits an infectious agent from an infected animal to another human / animal), virus,
bacteria or pathogen.
Alternatively, these diseases are given rise to by other factors such as genetics, environment
and lifestyle behaviours. These are classified into 4 groups which are genetic disease, dietary
disease, degenerative disease and environmental disease.
Genetic disease
Genetic diseases occur when mutations to a gene invalidate normal cellular function, leading
to the development of a disease phenotype. They can be caused by recessive, dominant or co
– dominant alleles. Precisely, one difference in the base sequence in a length of a DNA (a
gene), will cause an alteration in the nature of the protein encoded by the gene. Genes are the
hereditary material. Hence, genetic diseases can be inherited. These disorders often affect
many body systems due to them resulting from gene changes that are present in essentially
every cell in the body, most cannot be cured. However, procedures can be available to treat
some signs / symptoms, or reduce health consequences.
Three types of genetic disorders:
Single gene disorders
Single gene disorders are caused by DNA variations in a specific gene and also have
consistent patterns of inheritance. Single gene disorders may be diagnosed using
imaging, enzyme analysis and molecular testing. On condition that the mutation
resulting the state is known in the family, molecular testing will be simple and
, straightforward. An example of a single gene disorder may be ‘Sickle Cell Anemia’.
It is an inherited red blood cell disorder in which there are not enough healthy red
blood cells to carry oxygen throughout your body. The flexible biconcave disc shaped
red blood cells usually pass with ease across blood vessels. In sickle cell anaemia, the
red blood are shaped like sickles or crescent moons. These stiff, sticky cells can get
trapped in narrow blood vessels, which can lead to a decrease or obstruct the flow of
blood and oxygen to areas of the body. Unfortunately, there is no cure for people with
Sickle Cell Anaemia. However, treatments can prevent complications related to the
disease and relieve pain.
Chromosomal disorders
A chromosomal disorder is an abnormal condition due to something unusual in an
individual’s chromosomes. This frequently occurs due to one or more of the following,
Errors during dividing of sex cells (meiosis)
Errors during dividing of other cells (mitosis)
Exposure to substances that cause birth defects (teratogen).
Some signs of chromosomal abnormalities may be,
Poor growth
Intellectual disability
Learning problems
Problems with structures like the heart
In most cases, there is no treatment or cure for chromosomal abnormalities. However, genetic
counselling, physical therapy and medicines may help. Most chromosomal abnormalities are
not passed one from one generation to the next, such as Down syndrome and Turner
syndrome. The development of an extra copy of chromosome ‘21’ gives rise to Down
syndrome.
Complex disorders
Complex disorders result from the interaction of multiple genes, environmental and
lifestyle factors. Some examples may be Parkinson disease, asthma, autism,
Alzheimer disease etc. Despite the fact that complex diseases tend to run in families,
they do not have clear – cut patterns of inheritance as compared to single gene
disorders. Therefore, it is difficult to predict a person’s risk of inheriting or passing on
these diseases.
Complex diseases can be difficult to treat since they can be caused by both genetic
and environmental factors.
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