Unit 12: diseases and infections.
12A- Infectious and non-infectious diseases.
What is an infectious disease?
An infectious disease is a disease which are caused by pathogens. These diseases are
communicable diseases; this means that it can easily spread from one person to another.
Some infectious diseases can be cured and some of them can’t be cured.
What is a pathogen?
A pathogen is a disease-causing micro-organism that is harmful to the body. Pathogens are
what cause infectious diseases and can take many different forms.
A pathogen can enter the body in a number different ways:
Breathed in through the nose or mouth
Can be ingested from food or water
Entered through the cuts or bites in the skin
Can enter from other natural openings.
The five main pathogens are:
Bacteria
Viruses
Parasites
Fungus
Protozoa
Bacteria.
Bacteria is a prokaryotic, single celled organism that produces toxins and
reproduces quickly inside the body. A bacterial cell would enter the body
and then divide via binary fusion. This makes the cell divide and spread
throughout the body.
The structure of a bacteria cell is shown below:
Cytoplasm. The cytoplasm in a bacteria cell is where the chemical reactions in the
cell take place. The cytoplasm contains enzymes which help to speed up chemical
reactions in a cell. The cytoplasm covers the whole of the inside of the cell.
Nucleoid.
A nucleoid is a region that contains a single, free loop of DNA that contains the genetic
information of the cell. The nucleoid floats free in the cytoplasm.
Flagella. A flagellum is a tail like structure that helps the bacterial cell to move inside the
body. The flagellum is located on the outside of the bacterial cell.
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,Pili. The pili sticks one bacterial cell to another. The pili is located on the outside of the
bacterial cell as the pili branches out of it.
Ribosomes. Ribosomes manufacture proteins in a cell and are the site of protein synthesis.
A bacterial cell contains 70s ribosomes. This means that these ribosomes are smaller and
less active then 80s ribosomes, found in eukaryotic cells. Ribosomes are located randomly
inside of the bacterial cells.
Cytoplasmic membrane. A cytoplasmic membrane is another word for a plasma/ cell
membrane. A cell membrane is selectively permeable, which means that there are pores
that allow movement of molecules in and out of the cell. The cell membrane is located on
the outside of the bacterial cell.
Cell wall. The cell wall on a bacterial cell is made up of a protein called peptidoglycan. The
cell wall helps to maintain, strengthen and to protect the cell shape. The cell wall is located
outside of the cell membrane and is one of the outer layers of the cell.
Slime capsule. The slime capsule’s function is to provide an extra layer that helps to protect
the cell and helps the cell to not dry out. The slime capsule is a really thin layer that is
located on the cell wall and is the outer most layer of the bacterial cell.
Plasmids. Plasmids are loops of DNA that aren't attached to the nucleoid. Plasmid loops of
DNA are for resistance of antibiotics when the antibiotics attack the pathogen in the body.
The plasmid lies freely in the cytoplasm of the cell.
Tuberculosis.
What is tuberculosis?
Tuberculosis is caused by a bacterium called mycobacterium tuberculosis. It is a flu like
disease that can turn into a serious health condition but it can be cured if the condition is
treated within the early stages of TB, with proper treatment.
How can someone catch tuberculosis? (How is it spread).
Tuberculosis is an airborne disease. This means that tuberculosis is spread through the air.
Someone can catch tuberculosis by breathing in the infected cough and sneeze droplets that
are present within the air, when someone with TB coughs or sneezes.
Is TB asymptomatic?
Tuberculosis is asymptomatic if a person that has tuberculosis has a healthy and strong
immune system. However, as the stages of tuberculosis progresses, the symptoms of
tuberculosis would be more visible and no longer be asymptomatic. People with weaker
immune systems would find TB asymptomatic early on when contracting tuberculosis.
What are the symptoms of tuberculosis?
A continuous cough that does not go away after a prolonged period of time. (Usually
has phlegm or blood when coughing).
sweat a lot during the night
2
, high temperatures
constantly be always tired
The life cycle of tuberculosis (how TB progresses over time).
Tuberculosis (TB) comes in three stages:
1. Primary tuberculosis
2. Latent tuberculosis
3. Active tuberculosis
Primary tuberculosis.
This is the first stage of tuberculosis and it is when the bacteria (mycobacterium
tuberculosis), first enters the body. This is usually when someone inhales the infected
sneeze or cough droplets that are present within the air. In the primary stage of
tuberculosis, some people would not experience any symptoms of TB, but some people
would experience high fever/ temperature. People with stronger immune system would not
experience and symptoms but people with TB that have a weaker immune system would
experience mild symptoms.
Latent tuberculosis.
In the second stage of TB, the bacteria are inside the person’s body and tuberculosis can be
identified through tests done at the hospital. This is because the bacteria have started
multiplying. However, in this stage of TB the bacteria are still not properly active. This means
that some people will not experience symptoms, whereas other people would experience
symptoms like loss of appetite and high temperatures.
Active tuberculosis.
In the last stage of tuberculosis, the tuberculosis bacteria are multiplying constantly and are
really active. At this stage, a person would experience all of the symptoms of tuberculosis
and would feel really sick. People with stronger immune systems would not feel as bad as
people with weaker immune systems and in the last stage of the tuberculosis life cycle, a
person with TB is really contagious and is advised to stay away from others and isolate.
How does tuberculosis affect the body?
Tuberculosis mainly affects the body’s lungs as the lungs would constantly be coughing up
blood and phlegm and this would put a strain on them. Also, the body would experience
some aches and pains mainly in the chest area due to the strain that is being put onto the
lungs.
Does tuberculosis affect a person’s ability to lead a normal life?
Tuberculosis doesn’t really affect a person’s ability to lead a normal life and a person can
live with tuberculosis after and during treatment for tuberculosis.
Viruses.
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12A- Infectious and non-infectious diseases.
What is an infectious disease?
An infectious disease is a disease which are caused by pathogens. These diseases are
communicable diseases; this means that it can easily spread from one person to another.
Some infectious diseases can be cured and some of them can’t be cured.
What is a pathogen?
A pathogen is a disease-causing micro-organism that is harmful to the body. Pathogens are
what cause infectious diseases and can take many different forms.
A pathogen can enter the body in a number different ways:
Breathed in through the nose or mouth
Can be ingested from food or water
Entered through the cuts or bites in the skin
Can enter from other natural openings.
The five main pathogens are:
Bacteria
Viruses
Parasites
Fungus
Protozoa
Bacteria.
Bacteria is a prokaryotic, single celled organism that produces toxins and
reproduces quickly inside the body. A bacterial cell would enter the body
and then divide via binary fusion. This makes the cell divide and spread
throughout the body.
The structure of a bacteria cell is shown below:
Cytoplasm. The cytoplasm in a bacteria cell is where the chemical reactions in the
cell take place. The cytoplasm contains enzymes which help to speed up chemical
reactions in a cell. The cytoplasm covers the whole of the inside of the cell.
Nucleoid.
A nucleoid is a region that contains a single, free loop of DNA that contains the genetic
information of the cell. The nucleoid floats free in the cytoplasm.
Flagella. A flagellum is a tail like structure that helps the bacterial cell to move inside the
body. The flagellum is located on the outside of the bacterial cell.
1
,Pili. The pili sticks one bacterial cell to another. The pili is located on the outside of the
bacterial cell as the pili branches out of it.
Ribosomes. Ribosomes manufacture proteins in a cell and are the site of protein synthesis.
A bacterial cell contains 70s ribosomes. This means that these ribosomes are smaller and
less active then 80s ribosomes, found in eukaryotic cells. Ribosomes are located randomly
inside of the bacterial cells.
Cytoplasmic membrane. A cytoplasmic membrane is another word for a plasma/ cell
membrane. A cell membrane is selectively permeable, which means that there are pores
that allow movement of molecules in and out of the cell. The cell membrane is located on
the outside of the bacterial cell.
Cell wall. The cell wall on a bacterial cell is made up of a protein called peptidoglycan. The
cell wall helps to maintain, strengthen and to protect the cell shape. The cell wall is located
outside of the cell membrane and is one of the outer layers of the cell.
Slime capsule. The slime capsule’s function is to provide an extra layer that helps to protect
the cell and helps the cell to not dry out. The slime capsule is a really thin layer that is
located on the cell wall and is the outer most layer of the bacterial cell.
Plasmids. Plasmids are loops of DNA that aren't attached to the nucleoid. Plasmid loops of
DNA are for resistance of antibiotics when the antibiotics attack the pathogen in the body.
The plasmid lies freely in the cytoplasm of the cell.
Tuberculosis.
What is tuberculosis?
Tuberculosis is caused by a bacterium called mycobacterium tuberculosis. It is a flu like
disease that can turn into a serious health condition but it can be cured if the condition is
treated within the early stages of TB, with proper treatment.
How can someone catch tuberculosis? (How is it spread).
Tuberculosis is an airborne disease. This means that tuberculosis is spread through the air.
Someone can catch tuberculosis by breathing in the infected cough and sneeze droplets that
are present within the air, when someone with TB coughs or sneezes.
Is TB asymptomatic?
Tuberculosis is asymptomatic if a person that has tuberculosis has a healthy and strong
immune system. However, as the stages of tuberculosis progresses, the symptoms of
tuberculosis would be more visible and no longer be asymptomatic. People with weaker
immune systems would find TB asymptomatic early on when contracting tuberculosis.
What are the symptoms of tuberculosis?
A continuous cough that does not go away after a prolonged period of time. (Usually
has phlegm or blood when coughing).
sweat a lot during the night
2
, high temperatures
constantly be always tired
The life cycle of tuberculosis (how TB progresses over time).
Tuberculosis (TB) comes in three stages:
1. Primary tuberculosis
2. Latent tuberculosis
3. Active tuberculosis
Primary tuberculosis.
This is the first stage of tuberculosis and it is when the bacteria (mycobacterium
tuberculosis), first enters the body. This is usually when someone inhales the infected
sneeze or cough droplets that are present within the air. In the primary stage of
tuberculosis, some people would not experience any symptoms of TB, but some people
would experience high fever/ temperature. People with stronger immune system would not
experience and symptoms but people with TB that have a weaker immune system would
experience mild symptoms.
Latent tuberculosis.
In the second stage of TB, the bacteria are inside the person’s body and tuberculosis can be
identified through tests done at the hospital. This is because the bacteria have started
multiplying. However, in this stage of TB the bacteria are still not properly active. This means
that some people will not experience symptoms, whereas other people would experience
symptoms like loss of appetite and high temperatures.
Active tuberculosis.
In the last stage of tuberculosis, the tuberculosis bacteria are multiplying constantly and are
really active. At this stage, a person would experience all of the symptoms of tuberculosis
and would feel really sick. People with stronger immune systems would not feel as bad as
people with weaker immune systems and in the last stage of the tuberculosis life cycle, a
person with TB is really contagious and is advised to stay away from others and isolate.
How does tuberculosis affect the body?
Tuberculosis mainly affects the body’s lungs as the lungs would constantly be coughing up
blood and phlegm and this would put a strain on them. Also, the body would experience
some aches and pains mainly in the chest area due to the strain that is being put onto the
lungs.
Does tuberculosis affect a person’s ability to lead a normal life?
Tuberculosis doesn’t really affect a person’s ability to lead a normal life and a person can
live with tuberculosis after and during treatment for tuberculosis.
Viruses.
3
