Infections caused by pathogens e.g bacteria and viruses.
For example common cold, food poisoning and chest
infections
Non infectious disease- caused
by malfunctioning of the body
e.g cancer
Lifestyle
Coronary Heart
Disease (CHD):
-Poor diet (high in
saturated fat or
salt) -Smoking
-lack of exercise
All lead to high BP, which can damage the
heart and blood vessels, increasing risk of CHD
Cancer, result of uncontrolled cell division:
-Smoking (mouth, throat and lung cancer)
-Excessive exposure to sunlight; skin cancer
-Excessive alcohol intake; liver cancer
Risk Factor=
anything that
increases the
chance of getting
a disease
Pathogens
Organism that can
cause disease
Types of Pathogen
Viruses
HIV-Aids + Influenza
Bacteria
Myobacterium Tuberculosis
Entry into the body
Gas Exchange System
Mucus trap pathogens, cilia beat and move mucus
up trachea and out of the mouth
The Skin
Blood clots and dries to form a scab
Digestive System
Most pathogens killed by acidic conditions of the stomach
How they cause disease
1. Production of Toxins
2. Cell Damage- kill host cells
i). rupture host cell to release nutrients
ii) Break down nutrients for own use, this starves the cell
iii) cell dies, pathogens replicate inside cells and eventually they burst
The Immune Response
1. Phagocytosis
1. Phagocyte recognises antigens on surface
2. Cytoplasm of phagocyte moves around the pathogen, engulfing it
3. The pathogen is now in a phagocytic vacuole
4. A lysosome fuses with the phagocytic vacuole, the lysosomal enzymes break down the pathogen
5. Phagocyte then presents the pathogens antigens on its own surface in order to activate other immune system cells
2. T-Cell Activation (Cellular Response)
Type of white blood cell, has proteins on its
surface that bind to antigens on phagocytes
Some T-cells release substances to activate B cells. Others
attach to antigens on the pathogen and kill the cell.
3. B-Cell Activation& Plasma cell production (Humoral Response)
B Cells= Type of white blood cell
Covered with antibodies
(proteins that bind antigens to
form an antigen-antibody
complex)
Each B cell has a diff shaped
antibody on its membrane
Meets complimentary antigen+ binds. This, together with
substances released from
T-Cells activate the B-Cells
and cause them to divide (Plasma cells)
4. Antibody Production
Plasma cells are identical to B cells (clones) so they secrete loads of antibodies
specific to the antigen
Antibody Functions:
Coating pathogen so the phagocyte can easily engulf it
Binding to and neutralising toxins produced by pathogen
Antibody Structure
Proteins- made of chains of AA
monomers, linked by peptide bonds
Each antibody has a diff shaped variable region due to diff amino acid sequences