B2 Ventilation And Gas Exchange In Lungs

Question 1

Structure of humans lungs and ventilation system (components)

Answer 1

Trachea (wind pipe) - contains ciliated epithelial cells, cartilage, Goblet cells, smooth muscle
Bronchus - ciliates epithelial cells, goblets cells, smooth muscles, cartilages
Bronchiole - ciliated epithelial cells, smooth muscles
Alveolus - squamous epithelial cells, elastin

Question 2

Structure of the human lung and ventilation system (functions)

Answer 2

Ciliated epithelial cells - waft mucus out of airway
Goblet cells - produces mucous
Squamous epithelial cells - allows stretch and recoil
Smooth muscles - narrow airway
Elastin - allows stretch and recoil
Cartilage - gives rigidity

Question 3

Structure of the alveoli

Answer 3

Large surface area - millions of alveoli, providing more spaces for gas molecules to pass through
Short diffusion pathway - walls of alveoli are made of squamous epithelial cells are only one cell thick. Reduces the distances these molecules have to diffuse through.
Capillary network - alveolus us close to capillary which has a wall which is also one cell thick to give short diffusion pathway for molecules
Diffusion gradient - oxygen diffuses from high concentration inside the alveoli down a concentration gradient to an area of lower concentration in blood capillary and are maintained by ventilation
Moisture - layers of moisture lines of alveoli. Gases can only diffuse across the membrane if dissolved. This moisture allows oxygens to dissolve in order to diffuse into blood capillaries
Surfactant - chemically produced by the lungs to stop the alveoli from collapsing by reducing the surface tension of water

Question 4

Mechanism of breathing: ventilation ( inspiration)

Answer 4

External intercostal contract pulling rib cage UP & OUT

• Diaphragm contracts and flattens
• Thoracic cavity volume increases
• Pressure in lungs reduces this LOWERS the atmospheric pressure
• Air moves into lungs down
a pressure gradient - from a higher atmospheric air pressure to the lower air pressure of the thoracic cavity.

Question 5

Mechanism of breathing: ventilation ( expiration)

Answer 5

• External Intercostal (rib) muscles relax so rib cage moves DOWN & IN
• Internal intercostal muscles contract to pull ribs down and in during forced
lattens creases s, LOWER
expiration.
• Diaphragm relaxes and moves up (domes)
• Thoracic cavity volume decreases
• Pressure in lungs GREATER than atmospheric pressure
• Air moves out of lungs down
e thoracic pressure gradient.

Question 6

Diffusion of gases

Answer 6

Deoxygenated blood from the pulmonary artery has low concentrations of oxygen and high concentrations of carbon dioxide compared with the air inside the alveoli.
When blood reaches capillaries surrounding the alveoli as the oxygen diffuses into blood across the squamous epithelial membranes and the endothelial walls of the capillary, moving from higher oxygen concentration to the lower oxygen concentration.
Concentrated of CO2 in the blood from the pulmonary artery is greater than that inhaled air in the alveoli
Both gases move in opposite directions from higher to lower concentration through diffusion. Blood is then circulated away from the alveoli by contraction of the heart. Moves newly oxygenated blood away from the lungs back to the heart to be pumped around the body.
Circulation of blood by the heart and the ventilation of the air through the breathing maintains a concentration gradient at the alveoli squamous epithelial to ensure gases diffuse efficiently in either directions and do not reach equilibrium

Question 7

Pathway of oxygen from atmospheric to the blood (2/3m)

Answer 7

Mouth/ nose > trachea > bronchus > bronchioles > alveoli (epithelial cells) > capillaries endothelial cells > red blood cells

Question 8

Respiration minute volume of pulmonary rate

Answer 8

Respiration minute volume = ventilation x tidal volume

Question 9

Spirometer reading of lung volume definitions of tidal volume

Answer 9

Tidal volume - natural breathing volume

Question 10

Spirometer reading of lung volume definitions inspiration/ expiratory reserve

Answer 10

Extra volume required for deep breath

Question 11

Spirometer reading of lung volume definitions residual volume

Answer 11

Air that remains in the lungs to prevent collapse of alveoli

Question 12

Spirometer reading of lung volume definitions vital capacity

Answer 12

Is the maximum amount of air to a persons can expel from the lungs

Question 13

Peak expiratory flow

Answer 13

Measures the ability to breath out the air and. An monitor the degree of obstruction in the airway.
Process:

1. Before each use, make sure the sliding pointer on the peak flow meter is reset to the 0 mark.
2. Hold the PFM by the handle.
3. Stand up straight.
4. Remove chewing gum, candy, or food from your mouth..
5. Take a deep breath and put the mouthpiece in your mouth. Seal your lips and teet tightly around the mouthpiece.
6. Blow out as hard and as fast as you can. A “fast blast is better than a “low blow.
7. Note the number where the sliding pointer has stopped on the scale.
8. Reset the pointer to 0.
9. Repeat this 3 times. The 3 readings should be close together. If not, adjust your technique.
10. If you cough during a measurement repeat the measurement.

Question 14

Peak flow reading

Answer 14

Higher than average :
- little narrowing of airway
- good lung health
- good levels of exercise

Lower than average :
- respiration airway might be narrowing
- airway might be inflamed
- may be sign of asthma
- asthma getting worse
- COPD developing

Question 15

The use of spirometer

Answer 15

• A spirometer consists of a chamber filled with oxygen that floats on a tank of water. A disposable mouthpiece is connected to a tube.
• This is connected to the tank and the patient breathes in and out.
• Breathing in - removes oxygen from the chamber, so it moves down.
• Breathing out = pushes carbon dioxide in so the chamber moves up.
• The movement of the chamber up and down is recorded using a datalogger and produces a trace.
• Soda lime is attached to the tube to absorb carbon dioxide that is breathed out.
• This means the total volume of gas in the spirometer will gradually decrease.
• The volume of carbon dioxide breathed out is the same as the volume of oxygen breathed in.
• This means that as the carbon dioxide is removed the total decrease equals the volume of oxygen used by the person.
• The trace shows a slope and this can be used to measure the volume of oxygen used in a certain time.

Question 16

Effects of exercise

Answer 16

At rest - air moves in and out of your lungs about 12 times a minute.
Each breath renews air in your lungs and expels carbon dioxide in your body.
When you exercise or become frightened, your breathing becomes quicker and de
This supplies more oxygen and removes more carbon dioxide.
This is known as breathing rate.