Slides in this set
How breathing takes place.
1. The intercostal muscles relax making the rib cage move
down and outwards.
2. The diaphragm relaxes and moves down.
3. This increases the volume of the lungs, which decreases
the pressure. Air moves in from the higher pressure
outside the lungs into the lower pressure within the lungs.
4. The intercostal muscles contract making the rib cage
move inwards and upwards. The diaphragm contracts and
5. Volume in the lungs decrease making the pressure
increase. Air moves from a high to a low concentration
making the air leave the lungs.…read more
The mechanism causing air to enter and leave the lungs.
Breathing: To draw in and expel air using the lungs.
Respiration: Process in cells which releases energy from
Pulmonary Ventilation = Tidal volume x Ventilation rate
(dm3 min -1) (dm3) (min-1)…read more
· Large surface area to volume ratio (speed up rate of
· Very thin ( keep diffusion pathway short and allow materials
to cross rapidly.
· Partially permeable (allow selected material to diffuse easily)
· Movement of external medium
· Movement of internal medium
Creates a concentration gradient
Diffusion is proportional to :
(Surface area x Difference in conc')/Length of diffusion path.…read more
Causes and Symptoms
· One of two species of rod-shaped bacteria (mycobacterium or mycobacterium bovis)
· Persistent cough
· Loss of appetite- Leading to weight loss
· Coughing up blood
· Spread through air droplets (coughing, sneezing, laughing, talking)
· Can survive several weeks once droplets have dried
· Close contact with a person over a long period of time
· Crowded and poorly ventilated places
· Can spread from cows to humans
People more at risk
· People in close contact with infected people
· Work/live in long term care facilities (e.g. care homes)
· From countries where TB is common
· Have reduced immunity
Course of infection
· Bacteria grows and divides in upper regions of lungs with a good supply of oxygen
· Immune system responds, white blood cells go to site of infection and ingest bacteria
· Leads to inflammation and enlargement of lymph nodes- Primary infection
· Within a healthy person there are few symptoms and the infection is controlled within a few weeks, but some bacteria remain
· Years later, these bacteria re-emerge causing a second infection of TB- Post-Primary tuberculosis
· Infection occurs in top of the lungs but this time causes tissue to decay, causing cavities then lung tissue where the lungs repair themselves
· Sufferer coughs up damaged lung tissue containing bacteria and blood
· Without treatment, TB spreads to the rest of the body and can be fatal
· Tests for immunity (Vaccination for those who are immune is unnecessary)
· Better education about TB
· More and better housing
· Improved health facilities and treatment
· Better nutrition (stronger immune systems)…read more