Diseases and Homeostasis, gas exchange

Question 1

Define transmissible diseases

Answer 1

is a disease in which the pathogen can be passed from one host to another

Question 2

How can diseases be transmitted through

Answer 2

• Direct contact e.g through blood or other body fluids
• indirect contact e.g contaminated surfaces or food from animals or from airborne pathogens

Question 3

Our body defense systems

Answer 3

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

Question 4

Lymphocytes - white blood cells

Answer 4

Cells that tag foreign material (aka antigen) with antibodies targeting the material for destruction

Question 5

Phagocytes- white blood cells

Answer 5

Eat/engulf foreign material through phagocytosis

Question 6

antibodies bind to antigens on pathogens

Answer 6

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

Question 7

How to control the spread of diseases

Answer 7

Clean water supply
Hygienic food prep
Good personal hygiene
Waste disposal
Sewage treatment

Question 8

Process of vaccination

Answer 8

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

Question 9

Active immunity

Answer 9

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

Question 10

Passive immunity

Answer 10

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

Question 11

Why do we feel sicker from first infections?

Answer 11

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

Question 12

How does ventilation happen

Answer 12

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

Question 13

Inhalation

Answer 13

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

Question 14

Exhalation

Answer 14

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

Question 15

Cartilage in trachea

Answer 15

Your trachea is made up of rings of cartilage
It helps to keep trachea from collapsing

Question 16

Inside an alveolus

Answer 16

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

Question 17

Laws of diffusion

Answer 17

The movement of the oxygen from the blood to the cells also follows the law of diffusion.
⬇️
It’s highly concentrated within the blood
⬇️
Meanwhile the concentration is low within the cell
⬇️
Therefore the oxygen passes into the body cells

Question 18

Inspired vs expired air

Answer 18

• water vapour concentration is also higher in exhaled air compared to inhaled air

Question 19

Inspired vs expired air table

Answer 19

Gas Inspired air Expired air
Oxygen. 21% 16%
CO2. 0.04% 4%
nitrogen. 78% 78%

Question 20

Goblet cells in lungs

Answer 20

Epithelium produce and secrete mucus. They are named such as they look a bit like cups

Question 21

Mucus in lungs

Answer 21

The mucus traps bacteria, viruses and any other particles that enter our lungs

Question 22

Ciliated cells

Answer 22

Are the small hairs on the surface of epithelial cells. They push mucus and other small particles towards the nose and throat

Question 23

Effect of exercise in heart and lungs

Answer 23

Our rate of breathing increases and the tidal volume (air in and out per breath)
Our heart pumps faster