Unit 2: What factors affect human health?; Biology

WHO objective:

WHO works worldwide to promote health, keep the world safe, and serve the vulnerable.

Definition of health

• The World Health Organisation (WHO) defines health as 'a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity'

• This means that health is not just dependent on whether an individual is physically sick or not

  • There are lots of factors that should be considered when assessing the health of an individual which includes mental health as well as the level of social support in place

Justify whether or not governments are responsible for health:

Governments are fundamentally responsible for health as they play a crucial role in establishing public health infrastructure, regulating healthcare services, and ensuring equitable access to medical care for all citizens. They implement policies that promote preventive measures, manage health crises, and address health disparities among different populations. By funding research and responding to emergencies, governments not only protect public health but also contribute to economic stability, making their involvement essential for the overall well-being of society.

Bacteria:

Bacteria cause symptoms by producing toxins that damage cells and tissues, triggering an immune response. They can also invade and multiply within the body, leading to inflammation and tissue damage.

Virus:

Viruses cause symptoms by invading host cells and hijacking their machinery to replicate. When the virus replicates too much in the host cell, the cell will burst and cause the waste products to travel in the bloodstream and even infect neighboring cells. This process can lead to cell damage and death. Additionally, the immune response triggered by viral infection can cause inflammation and tissue damage.

Bacteria vs Viruses - Table

Healthy gut bacteria:

Gut bacteria plays an essential role in your digestive system. They help break down certain complex carbohydrates and dietary fibers that you can't break down on your own.

Probiotics:

Probiotics are living micro-organisms that when ingested or applied locally in sufficient numbers, benefit your body. They are friendly bacteria that help balance gut microflora and support the immune system.

What do probiotics contain?

A variety of microorganisms. The most common are bacteria that belong to groups called Lactobacillus and Bifidobacterium. Other bacteria may also be used as probiotics, and so may yeasts such as Saccharomyces boulardii.

What do probiotics do?

Boost the immune system, support respiratory health, Help your body maintain a healthy community of microorganisms or help your body's community of microorganisms return to a healthy condition after being disturbed. Produce substances that have desirable effects. Influence your body's immune response. They fight infections because they compete for needs. They also increase the ph of the surrounding areas which creates a hard environment for bad bacteria to grow.

Alexander flemming + antibiotics

Alexander Fleming, a scientist, was studying bacteria in a petri dish when he noticed that a mold spore had landed in the dish and where it grew, there were no bacteria. This mold was producing a substance (later named penicillin) that was stopping the bacteria from growing. This discovery revolutionized medicine, giving us the first effective antibiotic.

Effect of antibiotics

They are used to treat or prevent bacterial infections. They are used to kill bacteria or prevent them from reproducing and spreading. They do this by attacking the wall or coating surrounding bacteria and interfering with bacteria reproduction. The effects of antibiotics on probiotics can be beneficial to the body as they can effectively slow the growth and kill many types of infection, usually in a fast acting manner. In some cases, like before surgery, antibiotics can also prevent infections from occurring. On the other hand, antibiotics can also hinder probiotic growth inside the gut.

Because they are designed to kill all bacteria indiscriminately, a lot of probiotic bacteria can also deplete causing the immune system to be even more vulnerable than before. If antibiotics are overused or used to treat infections other than bacterial, it can cause the harmful bacteria to become antibiotic resistant hence proving the antibiotics ineffective.

How can bacteria be resistant to antibiotics:

Bacteria can evolve quickly because they reproduce at a fast rate. Mutations in the DNA of bacteria can produce new characteristics. A random mutation might cause some bacteria to become resistant to certain antibiotics, such as penicillin. Antibiotics usually kill bacteria, but in this case the mutation means the bacteria cannot be destroyed by the antibiotic. This evolution of antibiotic resistance in bacteria is an example of natural selection leading to evolution.

1. A random mutation occurs in the DNA of individual bacterial cells.

2. The mutation protects the bacterial cell from the effects of the antibiotic - it becomes antibiotic resistant.

3. Bacteria without the mutation die when the antibiotic is present

4. Antibiotic resistant bacteria survive and can reproduce with less competition from non-resistant bacterial strains.

5. The genes for antibiotic resistance are passed to the offspring.

6. Over time the whole population of bacteria becomes antibiotic resistant because the antibiotic resistant bacteria are best suited to their environment.

Pathogen

Pathogens are infectious agents and are organisms that cause harm and disease to the host. Eg. Bacteria or a virus

Pathogens enter the body through:

○ Eyes, ears, the mouth and the nose

○ Intravenous (injections)

○ Through open wounds or cuts

○ Through sexual intercourse (sexually transmitted)

Parasite:

A parasite is an organism that lives and feeds on or in another organism of a different species which also causes harm to the host organism

Host:

A host is an organism that harbors another organism, often providing nutrients and shelter.

Asexual reproduction:

Asexual reproduction is a process where an organism reproduces without the involvement of gametes, resulting in offspring genetically identical to the parent.

Types of Pathogens + examples

How a virus replicates inside the human body:

• A virus enters the host cell, and bursts its capsule and releases genetic material inside the cell.

• The virus DNA then enters the host cell's nucleus, taking over the cellular machinery and ribosomes which usually produces proteins and instead synthesizes virus DNA to produce more virus cells.

• This allows the cell to replicate the virus genomes and produce more than a million copies of itself.

• As a result, the new viruses burst out of the host cell and kills it, and then proceeds to enter new cells and make even more copies of itself until the immune system is struggling to suppress them.

Influenza virus replication:

• For example, the influenza viruses may enter your body through your repository system and takes up residence in a cell in your nasal passageway.

• Then the virus will take over the host cell's nucleus and produce millions of copies of itself before going and infecting other cells.

• The influenzas virus usually attacks your immune system, attacking healthy cells and producing common flu symptoms like cold, fever and cough.

• Although the influenza virus can weaken your immune system temporarily, the body's defenses quickly act to kill or attack the harmful virus cells.

Body’s defence mechanisms

1. First line of defense is the skin

2. When the pathogen enters the body, the second line of defense is phagocytes. Phagocytes are non-specific cells that first detect the pathogen and engulf and destroy foreign invaders through the process of phagocytosis using lysosomes. When phagocytes engulf the pathogen, they release the antigens on the surface of their cells.

3. The T helpers detect the antigens on the surface of the microphase and help alert the lymphocytes of foreign substances in the body.

4. Lymphocytes are the white blood cells involved in the specific immune response. They recognize specific antigens on invading pathogens. These produce antibodies. The antibodies created by the lymphocytes cause pathogens to stick together and make it easier for phagocytes to engulf them.

5. Antibodies are proteins produced by the immune system in response to the presence of a specific antigen. They bind to the virus, neutralizing or destroying its pathogens. An example of this is when a person becomes infected with influenza, their immune system makes specific antibodies to combat the virus.

Antibodies:

They are proteins produced by the immune system that recognize and target specific pathogens, helping to destroy them. Antibodies are chemicals secreted by lymphocytes. They are Y Shaped. They bind to antigens . They are specific where each antibody binds only to one type of antigens.

Antibiotics:

They are medications that can kill or stop the growth of bacteria. They are very specific and won't work against viruses or other pathogens.

Antigens:

Antigens are molecules on the surface of pathogens that the immune system recognizes as foreign. This triggers the immune system to launch an attack.

Vaccinations:

These are like controlled exposures to a weakened or inactive form of a pathogen. They train your immune system to recognize the antigen of a specific disease, so it can fight it off if you encounter the real pathogen later.

Edward Jenner & Vaccinations:

• Edward Jenner noticed that milkmaids who had gotten cowpox, a milder disease related to smallpox, never seemed to get the more serious smallpox. He took a pus sample from a cowpox blister and inoculated a young boy. The boy developed a mild illness but recovered. Later, when exposed to smallpox, the boy remained healthy.

• Jenner repeated his experiment 23 times to prove his theory. In 1798 he published a book describing how to prevent people from catching smallpox by injecting them with cowpox. He called his method vaccination because vacca is the Latin word for ‘cow’.

How vaccination works

1. Weakened or dead bacteria are introduced into the body. This vaccination is normally injected inside the body.

2. This causes the immune system, specifically the white blood cells, to produce complementary antibodies, which target and attach to the antigens.

3. These white blood cells clump pathogens together to make the process of phagocytosis easier.

4. White blood cells engulf the pathogens.

Memory cells

Long-lived immune cell that has the ability to recognise a foreign particle that it previously encountered and consequently mount a faster and stronger immune response

Sterilisation

Sterilisation is the process of eliminating all forms of microbial life, including bacteria, viruses, fungi, and spores. It's commonly used in medical settings to prevent the spread of infection. Here's how it works:

• Heat: High temperatures can denature proteins and damage cell structures, killing microorganisms. This can be done through boiling, autoclaving (steam under pressure), or dry heat sterilization.

• Chemicals: Chemical disinfectants like bleach, alcohol, or iodine can disrupt cell membranes or inactivate proteins, killing microbes.

• Filtration: Passing liquids or gases through a filter with pores small enough to trap microorganisms is another method.

Aseptic technique:

Aseptic technique is a set of practices designed to eliminate or minimize the presence of microorganisms (bacteria, viruses, fungi, spores) in a specific area. This is crucial in medical settings to prevent the spread of infection and protect both patients and healthcare workers.

Disinfection vs Sterilization:

Disinfection reduces the number of microorganisms on a surface or object to a safe level, but it doesn't necessarily eliminate all spores. It's suitable for non-critical items like countertops or equipment that won't directly contact sterile tissues.

Disinfection vs. Sterilisation table

Herd Immunity:

• Herd immunity, also called population immunity, is a type of indirect protection that occurs when a significant percentage of a population has become immune to an infection. This can happen through previous infections or vaccination.

• Gives protection to vulnerable people such as newborn babies, elderly people and those who are too sick to be vaccinated.

Epidemic:

It's a sudden outbreak of a disease that spreads rapidly through a population. This can happen when a new pathogen emerges, or if there's a decrease in herd immunity due to factors like low vaccination rates.

Pathogens are spread through:

• Direct contact

• Airborne transmission

• Bodily fluids

• Indirect contact

• Vectors

• Food and water

Inherited diseases

Inherited diseases are caused by genetic mutations passed down from parents through their reproductive cells (sperm or egg). These mutations can affect genes that control various bodily functions, leading to disease. Examples include cystic fibrosis and sickle cell disease.

Diet and it’s impact on inherited diseases

Diet: Eating a balanced diet that provides the right amount of energy and nutrients helps maintain good health whereas a poor diet can lead to deficiencies, obesity, diabetes and poor mental health

Stress and it’s impact on diseases

Stress: Constantly being under stress can lead to cardiovascular issues (such as high blood pressure, increasing the risk of CHD) and poor mental health

Standard of living and it’s impact on diseases

Life: Where a person lives and their income can have a profound impact on health - this affects the standard of healthcare that is accessible to them (and what they can afford), what food they buy etc.

Transmitted diseases

Transmitted diseases are caused by pathogens that invade the body from an external source. These are not passed down through genes. Examples include the common cold (caused by a virus) or strep throat (caused by bacteria).