science medical technology

epidemic

a widespread occurrence of an infectious disease in a community at a particular time

endemic

a disease regularly occurring within an area or a community

pandemic

a widespread occurrence of an infectious disease over a whole country or the world at a particular time

disease

a disorder of structure or function in a human, animal or plant, especially one that has a distinctive group of symptoms, signs, or anatomical changes and often a known cause

infectious disease

an illness caused by pathogens, microorganisms like bacteria, viruses, fungi, or parasites

non-infectious disease

a medical condition that cannot be spread from one person to another and is not caused by pathogens like bacteria or viruses

antibody

a protein produced by the immune system that identifies and neutralises foreign substances like viruses and bacteria 

antigen

a substance that can trigger an immune response and cause the body to produce antibodies against it

smallest unit of the body affected

the cell

infectious disease examples

• cold

• flu

• COVID-19

examples of non-infectious diseases

• cancer

• diabetes

• asthma

types of pathogens + diseases

bacteria:

• strep throat

• food poisoning

• UTI’s

viruses:

• COVID-19

• HIV/AIDS

• chicken pox

fungi:

• ringworm

• athletes foot

• yeast infections

first line of defence

• respiratory tract

• skin

• tears

• large intestine

• coughing and sneezing 

• bladder

tears in first line of defence

• wash away irritating substances

• lysozyme kills many bacteria

skin in first line of defence

• provides a physical barrier to entrance of microbes

• acidic pH discourages the growth of organisms

• sweat and oil gland secretions kill bacteria

large intestine in first line of defence

• normal bacteria inhabitants form a protective barrier 

coughing and sneezing in first line of defence

• action of coughing, sneezing, vomiting helps clear surface of pathogens

bladder in first line of defence

• urine washes microbes from urethra 

respiratory tract in first line of defence

• mucus traps organisms

• cilia sweeps away trapped organisms

stomach

• acid kills organisms

second line of defence

phagocytosis and inflammation

phagocytosis

certain white blood cells engulf and destroy invading microorganisms, dead cells, or debris inside the body. This kills and destroys pathogens that have entered the tissues and prevents disease.

phagocytosis process

1. detection

• phagocyte detects and moves towards the pathogen using chemical signals

2. engulfing

• phagocyte extends the cell membrane around the microbe, trapping it in a sac called a phagosome 

3. digestion

• phagosome fuses with a lysosome

• enzymes and reactive chemicals break down and destroy the pathogen

4. absorption or excretion

• useful parts are absorbed by the cell

• waste material is released from phagocyte

inflammation

• cells release chemicals after being damaged by pathogens, cuts, or irritants

• chemicals signal a problem and trigger an inflammatory response

• nearby blood vessels widen and become more leaky

• allows more blood, oxygen, and immune cells to reach the infected or injured area

• leaky blood cells allow plasm, phagocytes, and clotting factors to move into the tissue

• temperature rises to help phagocytes work faster and directly destroy pathogens

• swelling is caused due to liquids leaking out of widened blood vessels into surrounding tissues

main role of inflammation

to increase the rate of phagocytosis

third line of defence

along with engulfing pathogens, phagocytes release special chemicals that cause other white blood cells called b-lymphocytes and t-lymphocytes to be produced to fight specific pathogens

B and T lymphocytes

• b-lymphocytes produce antibodies to destroy pathogens outside of body cells

• t-lymphocytes destroy pathogens by producing chemicals that destroy body cells containing pathogens

• every pathogen is unique so different, specific t-cell and b-cell/antibody is needed for each pathogen

antibodies third line of defence

• produce b-lymphocytes

• each is unique to a specific pathogen

• antibodies bind directly to the pathogen and kill it or they bind pathogens together so they can be engulfed by phagocytes, or antibodies activate chemical toxins which destroy pathogens 

• making antibodies takes several days so it takes time for the body to fight some infectious diseases

memory cells

when the body has developed an antibody, it will ‘memorise’ the ‘recipe’ in memory t and b cells so more antibodies can be made quickly if the same pathogen invades the body again

b-lymphocytes

destroys pathogens by producing antibodies, which act as markers to neutralise pathogens or tag them for destruction by other immune cells

t-lymphocytes

destroy pathogens through two primary mechanisms: helper t cells signal and direct the immune response, while cytotoxic t cells directly kill infected or cancerous cells by inducing them to undergo programmed cell death

cause and effect of disease

cause: infectious and non-infectious diseases

effects: 

• physical - visible or measurable body changes 

• functional - loss of normal body functions

• cellular - damage to cells or tissues

• long-term - chronic effects or complications

light microscope - key tech

• allowed scientists to see cells for the first time

• simple, inexpensive, and can view living cells

• limited magnification and resolution

electron microscope

• revealed fine cell structures like organelles

• very high resolution and magnification 

• expensive, requires dead specimens, complex preparation

DNA sequencing

• enabled scientists to determine exact order of DNA bases, leading to understanding of genes, mutations, and heredity

• accurate mapping of genomes: helps in medical diagnosis and biotechnology 

imaging technologies (MRI, CT, PET scans)

• helped study living organisms without surgery; shows internal organs in detail

• non-invasive, useful in medical diagnosis

• very expensive