Ch. 10 - Disease and Immunity

Pathogen – disease causing microbes • Infectious agent or germ that causes disease or illness in the host • The host is your organism in which parasite or pathogen is damage • It can be a virus, bacteria, fungi, protozoa, parasite, or even a protein.

Infection – the entry of a pathogen into the host body

Toxins – chemicals produce produced by the pathogen which cause damaged to the host

Symptom – any feature that you experience after infection due to the pathogen, such as vomiting, soreness, or fever, et cetera

Transmission – the movement of a pathogen from one host to another

Disease – an unhealthy condition of the body or mind

Transmissible diseases: There are two basic types, communicable diseases, and non-communicable diseases • Communicable disease – disease which spreads from one host to another (E.g., a cold) • Non-communicable disease – disease which doesn’t spread from one host to another (E.g., cancer)

Transmission can happen in two ways, direct contact or indirect contact: • Direct contact – the pathogen is passed directly from one host to another by transfer of body fluids, such as blood or semen (E.g., HIV) • Indirect contact – the passage in leaves a horse and is carried in some way to another host

Ways of indirect contact: 1. By air 2. Indirect contact with the surface 3. By food 4. Insect 5. Rabid animal

The Immune Response: All cells have proteins and other substances projecting from the cell membrane. These are known as antigens and a specific to that type of cell. The way lymphocytes react and respond to pathogens by producing antibodies is called the immune response

Antibodies – proteins that recognize and bind to antigens Antigen – a protein on a foreign object, the stimulate the immune system to produce antibodies Antigens and antibodies are complimentary to each other

Lymphocytes – have receptors to detect any antigen of the surface of cells and recognise any that are foreign. They then make antibodies which are a complementary shape to the antigen on the surface of the pathogen cell

Agglutination – the clamping of passaging excels owing to the binding of antigen and antibodies • Movement is slowed down • Reproduction is stopped • Give signals for phagocytes to come and engulf • Phagocytes can easily engulf as the antigen can’t move nor reproduce

Memory Cells – long lived cells produced by the division of lymphocytes that have contacted their antigen • They are able to respond quickly to subsequent contact with the same antigen • The thereby remove the need force and identification • They are converted from lymphocytes once there is no more any need for that specific antibody

Phagocytes – • The phagocyte meets the bacterial cell – the membranes fuse • Phagocyte traps pathogen in the Phagosome • Phagocyte releases enzymes, which destroys and kills the pathogen • This process is known as Phagocytosis

Active Immunity – making antibodies and developing memory cells for future response Slow, acting and long lasting Two ways: 1. Body has become infected, so lymphocytes start working 2. Vaccination

Passive Immunity – being fed or receiving ready-made antibodies Fast acting and short lasting Example, examples are breastmilk and injected antibodies such as rabies or tetanus

Vaccination – • A method of giving antigens stimulate the immune response through active immunization • The passage injected into the body may be dead or attenuated (weaker form of the same pathogen) • It is an immune biological process designed to produce specific protection by creating memory cells • The vaccine is antigenic, not pathogenic

Herd Immunity – The idea that if a large enough percentage of the population is vaccinated, it provides protection for the entire population because there are fewer possible hosts

Cholera – • Vibrio cholerae • An acute denial illness caused by infection of the intestine with Vibrio cholerae • Spread through swallowing contaminated water or food • Often mild or without symptoms, but sometimes be severe or life-threatening • Comma shaped

The deadly effects of this disease are a result of a toxin the bacteria produce in the small intestine – • The toxin causes the body to enormous amount of water • This leads to diarrhoea and rapid loss of fluids and salt (electrolytes) • Dehydration leads to a rapid loss of minerals in your blood that maintain the balance of fluids in your body • This is called an electrolyte imbalance

Effects of electrolyte imbalance – • Muscle cramps • Shock – low blood volume causes a drop in blood pressure and a drop in the amount of oxygen in your body If left untreated severe hypovolemic shock can cause death in minutes

How does diarrhoea occur? 1. Bacteria releases toxins 2. Toxins stimulate the walls of the small intestine to release chloride ions (Cl-) 3. Thus, water potential reduces in the lumen 4. Water moves out from the blood vessels 5. Excess water exits the body through ejection in the form of diarrhoea