diseases and immunity

3 lines of defence against pathogens

• Physical barriers

  • Skin

  • Hair in the nose

• Chemical barriers

  • Acid in the stomach

  • Mucus

• White blood cells

  • Phagocytes

• Lobed nucleus to squeeze out of gaps out of capillaries

  • Adaptation

  • To go out without damaging

• Non-specific pathogen attacking

• Carry out phagocytosis

• Lymphocytes

  • Enlarged nucleus

  • Specific for a particular pathogen

Role of lymphocytes in immunity

• Antigen

• a toxin or other foreign substance which induces an immune response in the body

• A protein found on the surface of cells and it has a specific shape

• Lymphocytes identify antigens on pathogens as non-self (foreign)

• Receptors on lymphocytes are complementary to the shape of an antigen

• Little shapes coming out of the circle represent receptors and there is only one antibody that is complementary to it

• Lymphocytes bind to antigens e.g. bacteria because of the complementary shapes

• Lymphocytes that bind to an antigen divide and increase in number

  • Some of the cells become memory cells and can last in the body for an entire lifetime

  • Memory cells are the basis for immunological memory

    • The ability of the immune system to respond more rapidly and effectively to pathogens that have been encountered previously

    • When the same pathogen is encountered again, memory cells quickly identify it and divide to form more memory cells

  • Some of the cells become antibody producing cells or plasma cells

• Antibodies are Y-shaped proteins which destroy specific pathogens e.g. Antibodies against TB bacteria will not destroy any other pathogen

• When the same pathogen is encountered, a secondary immune response occurs which is faster and is more effective

• For every cubic millimetre of blood, you have two of a certain lymphocytes. After infection, the cells increase for every cm^2

• Higher gradient because of a faster reaction

Vaccination

• A method of preventing infections

• An atenuanted/weakened pathogen in injected into the body

• A primary immune response occurs

  • Antibodies and memory cells are made

• When the same pathogen is encountered again, a secondary immune response occurs which is faster and more efficiency at destroying pathogens

Types of immunity

• Active

  • The body in infected by a pathogen and it makes its own antibodies and memory cells.

    • Long lasting

    • Memory cells are made and can last a lifetime

  •  e.g. begin infected naturally or vaccination

• Passive

  • Receives ready-made antibodies

  • Fast but short lived

    • e.g. pregnancy, antibodies can cross placenta from mom to fetus. Gives fetus quick protection without having to suffer

    • Brestmilk also releases antibodies

Cholera

•  what causes it?

  • Type of pathogen: Bacteria

  • Name of pathogen: Vibrio cholerae

  • Pathogen carries in contamminated H20 and food

• The pathogen within the body

  • The pathogen comes in, intestines secrete a toxin that causes ____

  • Causes excess chlorine enzymes to enter the intestine

  • Chlorine ions enter and water potential decreases

  • Water then follows the chlorine ions and enter the small intestines, as a result it leads to diarrhea/watery stools forming

• Symptoms/signs

  • Diarrhea

  • Dehydration

  • Loss of ions/salts

• Treatment

  • ORS

    • Oral rehydration solution

Au - arbitary units

• Lag

  • Initial growth

  • Lf - low population density so that is why it starts off slow

• Exponential/log

  • Rapid growth

  • Population explosion

  • Somewhere we have the acceleration and deceleration period

    • Acceleration

      • We are just increasing, plenty of resources for reproduction and growth

    • Deceleration

      • Slows down but it is still increasing

  • Lf -

• Stationary

• Theoretical

  • If it was optimum conditions, how much would this grow

• Carrying capacity

  • Maximum population an ecosystem can sustain

    • Should be able to provide a habitat or space

    • Should be able to provide everything they need to survive

  • Once reached we have no growth

  • Similar to a classroom

    • You can fit about 30 students and can move around unrestricted

• Death

  • Begin to die from lack or resources because they finished off. They die rapidly

Pyramid of energy

• Feeding and energy

• Feeding habits and energy transfer

Pyramid of biomass

Pyramid of numbers

• Helps you trace on how something can be passed on given the trophic levels

  • Lead

Transmission of pathogens                                                                                                                          

• A pathogen is a microorganism that causes diseases

  • They get into our bodies and breed there

  • There are four kinds that act as pathogens

    • In the table above

• A person where the pathogen lives and breeds is called a host

  • Usually passed from one host to another

    • Transmissible disease

• Inside the body these damage the body

  • Some damage by living in the cell and using its resources

  • Some harm cells by releasing toxins

    • Spread around the body and cause symptoms

      • High temperature

      • Rash

      • Feeling ill

  • Some produce dangerous poisonous toxins

How pathogens enter the body

They enter through transmission

• Movement of pathogen from one host to another

• Entry of a pathogen into a body is called infecting

Direct contact

• From an individual to another through touch from an infected individual to another

  • AIDS through blood

• Can be from touching fungi

  • Skin infection

    • Can be from sharing a towel

    • Athlete's foot

Indirect transmission

• Breathing in droplets

  • Moisture in the air

    • Covid-19, cold, influenza

  • Sneezing, coughing

• Touching a surface

  • Putting your hand near your face after

• Eating or drinking water that contains pathogens

  • Salmonella

  • Food poisoning

    • Food should be washed carefully and taken care of well in storage

    • Some bacteria does not die from heat

• Contact with animals

• Cholera

  • Transmitted in water

    • Swimming or drinking infected water

Body defences

Help protect the body against pathogens and foreign invaders

• Skin, mucus, hair prevent pathogens from entering parts of the body

  • The ones that manage to get through are usually stopped by white blood cells

A clean water supply

Source of water that provides clean and fresh water that can be used

• Water is used for many things

  • Drinking, washing, preparing food

• Not safe water can carry pathogens

  • Some contain cholera or polio

• Clean water is a basic health need

  • Water is filtered before being sent through pipes

Food hygiene

• Good food hygiene reduces the chances of getting ill

• Getting ill from food can be prevented by

  • Keeping your own bacteria away from the food

    • Wash your hands

    • Wear someone on your head to keep your hair away

    • Don't cough or sneeze over food

  • Keeping animals away from food

    • Rats and mouse usually cation

  • Not keeping food in warm temperature for too long

  • Keep raw meat away from other foods

• Horseflies spit and feed on food

  • Cover food when done cooking

• Leaving food out when warm is the ideal temperature for most pathogens to breed

  • Food in fridge

  • Reheating food

Personal hygiene

Waste disposal

Sewage treatment

Cholera

The immune response

Antibodies

Memory cells

Vaccination

Active and passive immunity

Controlling disease by vaccination

Covid-19