Diseases and Homeostasis, gas exchange Flashcards
Biology topic 4
Define transmissible diseases
is a disease in which the pathogen can be passed from one host to another
How can diseases be transmitted through
- Direct contact e.g through blood or other body fluids
- indirect contact e.g contaminated surfaces or food from animals or from airborne pathogens
Our body defense systems
Mechanical barriers- skin and hairs in the nose
Chemical barriers- mucus and stomach acid, antibacterial tears
Cellular barriers - phagocytosis and antibody production by white blood cells. Can be enhanced by vaccination
Lymphocytes - white blood cells
Cells that tag foreign material (aka antigen) with antibodies targeting the material for destruction
Phagocytes- white blood cells
Eat/engulf foreign material through phagocytosis
antibodies bind to antigens on pathogens
Antigens are any structure that can be identified by an immune system (usually protein).
Each organism has its own unique antigens
The shape of the antigen is complimentary to the binding groove on the antibody
Once the antibody-antigen complex is formed it marks the foreign material for destruction by phagocytes
Process of vaccination
1) a weakened pathogen or specific antigen is put into the body
2) the antigen stimulates lymphocytes to produce antigens
3) complimentary antigens bind to the antigen tagging it for destruction by phagocytes
4) memory cells are produced that allow for the antibody to be produced rapidly in the future therefore giving up immunity
Active immunity
Defence against a pathogen by producing the antibody within the body
Is gained after an infection by a pathogen or by vaccination
Memory cells are produced
Passive immunity
Short term defence against a pathogen by antibodies acquired from another individual e.g mother to infant from milk, mother to foetus through blood
Important for new borns: get all antibodies from the mother
Does not produce memory cells
Why do we feel sicker from first infections?
It takes our body many days to create antibodies that will fit an antigen if we have never been exposed to it.
The second time our body is exposed it recognises the antigen much faster and can start producing antibodies within hours
How does ventilation happen
1) the diaphragm, which is a sheet of muscle that separates the thorax (chest) from the abdomen.
2) the intercostal muscles which lie between the ribs
Inhalation
Internal intercostal muscles relax and external, intercostal muscles contract, pulling your ribs up and out. Diaphragm also contracts and flattens.
⬇️
Volume of thorax increases
⬇️
Air pressure in thorax decreases, creating a negative pressure
⬇️
Air enters the lungs to equilibriate pressures
Exhalation
Internal intercostal muscles contract and external intercostal muscles relax, pulling your ribs down and in. Diaphragm relaxes and moves up
⬇️
Volume of thorax decreases
⬇️
Air pressure in thorax increases, creating a positive pressure
⬇️
Air exits the lungs to equilibriate pressures
Cartilage in trachea
Your trachea is made up of rings of cartilage
It helps to keep trachea from collapsing
Inside an alveolus
Oxygen makes its way to special
bundles of air sacs called alvoli.
Alveoli are specialised for
maximising rate of diffusion in
multiple ways:
1. Covered in capillaries, reducing
diffusion distance
2. Alvoli only 1 cell thick, reducing
diffusion distance
3. Large surface area in contact
between capillaries and alveoli
4. Blood is flowing through
capillaries, maintaining
concentration gradient
