Distinction assignment from BTEC Applied Science Unit 12 - diseases and infections. unit 12A includes characteristics of the 5 main types of pathogen and the causes of non infectious diseases. it also includes the effect these diseases have on the body and how they progress over time and develop.
Infectious diseases:
Bacteria
Bacteria are small prokaryotic organisms. Bacteria are single
celled and have no nucleus or membrane bound organelles.
Because there is no nucleus, the DNA is stored in a single loop
around the cell. Bacteria reproduce rapidly and damage cells in
the body. The bacterial cell has a flagellum, pili, plasmid,
ribosomes and a cell wall. Bacterial cells do not have mitochondria
for aerobic respiration. The flagellum provides movement to the
bacteria cells. The ribosomes are responsible for protein synthesis
and the pili allow the cell to stick to other surfaces.
Bacterial disease – pneumonia
Pneumonia is a disease caused by bacteria. Pneumonia causes an
infection in the lungs which leads to inflammation of the alveoli.
Very young people or very old people are more likely to get
pneumonia. The severity of pneumonia cases can vary however, all
cases will require treatment at the hospital. Pneumonia can occur
in one or both lungs and is caused by bacteria, fungi, or viruses.
Streptococcus pneumoniae is the specific bacteria that causes
pneumonia. It is a gram-positive bacterium which can be
transferred from person to person. This means that pneumonia is
a communicable disease. Because streptococcus pneumoniae is
gram positive, it has a single layered smooth cell wall with a thick
peptidoglycan layer. The cell wall helps provide shape for the bacteria. This bacterium enters
through the mouth and can enter with food or droplets in the air when people cough and
sneeze. Once in the respiratory system, streptococcus pneumoniae undergoes binary fission.
This process is where the bacteria replicates itself and the severity of pneumonia will increase.
The alveoli will become inflamed and will result in breathing problems and coughs. Antibiotics
can be used to help treat and reduce symptoms of bacterial pneumonia.
Life cycle of bacteria cell:
There are many different stages within the life cycle of a bacteria cell. The lag phase is when the
bacteria adjust to its new environment and prepare themselves for replication. They produce
amino acids and the DNA is copied. If the cell was previously damaged, during the lag phase it
will be repaired. The exponential phase is the next stage in the cycle, and during this stage the
bacteria will replicate rapidly. Binary fission will result in 2 daughter cells being produced. This
stage will continue until there is a limiting factor. Temperature or lack of nutrients could be a
limiting factor. The next stage is the stationary phase. The cells will no longer be rapidly
multiplying, and the number of cells being produced and the number of cells dying will be
, balanced. The reason for the slowing down of cell division is due to a limiting factor. The death
phase is the final stage of the cell cycle and this is where cell growth is permanently stopped.
Eventually all the cells will die and there will be no more to replace them.
Parasites
Parasites are a type of pathogen that require a host for its
survival. Endoparasite and epiparasite are the 2 types of
parasites. Tapeworm and heartworm are examples of
endoparasites that live inside the host. Epiparasite feed off
of and survive by taking nutrients from other parasites.
This is known as a symbiotic relationship where the
parasite benefits from the host being harmed. Parasites are
harmful to humans and can enter the body by
contaminated food or water or by touching the infected individual. Some parasites can adapt
and disguise themselves from the host's immune system.
Parasitic disease – lymphatic filariasis
Lymphatic filariasis is a tropical zoonotic
disease caused by parasitic worms.
Threadworms are parasitic worms which
affect the human lymphatic system. The
lymphatic system plays a crucial role in
regulating fluid levels and fighting infections.
People who suffer from lymphatic filariasis
have a weakened immune system as some of
the symptoms are inflammation,
lymphedema and edema. Lymphedema is the
buildup of lymph fluid in the lymphatic
system and edema is swelling caused by
buildup of fluid in your arms and legs. Mosquito bites are the cause of filariasis. When a
mosquito bites someone with filariasis, the mosquito then gets infected which means everyone
who now gets bitten by the mosquito will get infected with filariasis. This is because the filarial
worms from the infected person's blood infect the mosquito and then the worms pass over into
other people's bloodstream when bitten by the mosquito. In severe cases, this disease can lead
to permanent disability.
Life cycle of a parasite:
There are three main stages in the life cycle of a parasite: growth, reproduction, and transmission. The
stages can be direct or indirect. Indirect life cycles allow the parasite to be transmitted to another host
without other species. Direct life cycles require an intermediate species for a parasite to change hosts.
Transmission to the host: can be either direct or indirect. Direct is when the parasite enters the body
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