Introduction to Respiratory System

Question 1

what are the functions of the respiratory system (5)

Answer 1

1. Gaseous exchange
2. Acid-base balance
3. Phonation (production of vocal sound and speech)
4. Warming, humidification, filtration of gas
5. Defence against airborne pathogen

Question 2

what are the two divisions of resp tract - which parts are respiratory / non respiratory

Answer 2

• Upper respiratory tract: oro-pharynx and larynx: non respiratory
• **Lower respiratory tract

i) the conducting airways.**
This is from the trachea down to the small bronchioles, _non-respiratory

ii) _
* *Respiratory regions:** the alveoli and terminal bronchioles. These are the respiratory components of the lungs

Question 3

Answer 3

Question 4

the airway tree divides how many times? into what two subparts?

Answer 4

The airway tree divides 23 times:

• first 16 divisions make up the **conduction airways
• the last7 are the respiratory zone**

Question 5

Answer 5

Question 6

what is a typical tidal breath (where you inhale normally at rest): X litres?

what is the total expansion (Y litres) of aleovli? why is it different t^o?

Answer 6

• typical tidal breath = 0.5 L (Supposing we have a total of 5x108 alveoli)
• total expansion in all the alveoli = 0.4 litres. 20% of expansion during inlation comes from respiratory bronchioles

= . During normal breathing, they do not go from fully collapsed to fully inflated, they stay partially inflated even at full expiration.

Question 7

what happens to the elastic fibres around the alveoli during expiration?

Answer 7

During normal expiration:
the elastic fibres around the alveoli produce a passive ‘elastic recoil’: shrinks alveolar volume, but they do not collapse completely.

Question 8

Answer 8

Question 9

where in the resp. system is there no gaseous exchange?

what are features of conducting airways

• what type of cells found there?
• what else?

Answer 9

• in the conducting airways: trachea, bronchi and brionchioles. stops at the terminal bronchioles
• *Ciliated pseudostratified columnar epithelium (**or sometimes simple columnar) yet this varies with level
• *Cartilage/smooth muscle** is present in the conducting airways yet varies with level
• *Glands**, which are both sero-mucous and sub-mucosal

Question 10

what is the volume of the conducting airways?

Answer 10

150-200ml. When you exhale, you have to breathe out the volume of the conducting airways first before you exhale alveolar gas. This volume of gas (150-200ml) is sometimes referred to as dead space gas.

Question 11

where does the lower respiratory tract start?

which cells line the resp tract?

Answer 11

lower resp tract: starts at the top of the trachea

cells: ciliated epithelium cells

Question 12

the total area s.a. of all alveoli = ? m²

Answer 12

total area s.a. of all alveoli = 70 m²

Question 14

what are cells in the alveoli called?

what are the two types?

Answer 14

= pneuomocytes

1. type 1 pneumocytes (squamous: 90% of area)
2. type 2 pneumocytes (cuboidal: 10% of area)

Question 15

what do type 2 pneumocytes secrete? (and what are the two roles of this) what aka?

Answer 15

aka: septal cells
- produce surfactant -> reduces the surface tension in the alveoli & stops alveoli collapsing

Question 16

which three layers does gax exchange go across in alveoli/

Answer 16

1. alveolar epithelium
2. interstitium (mostly water)
3. endothelium of capillary

total distance = < 1 um

Question 17

mucus -

• where found in resp. tract?
• secreted from what?
• how are dust particles trapped in mucus?
• whats in the mucus?

Answer 17

mucus:

• *-** secreted from goblet cells
• lines epithelium of whole airways EXCEPT alveoli
• turbinate bones in the nasal passages spin the air flow into a vortex so that dust particles and some airbourne pathogens are thrown into mucus
• mucus contains antibodies and antibiotic peptides to kill pathogens, dentritic cells also found - which causes more mucous to be secreted

RESP. FIRST LINE OF DEFENCE V PATHOGEHNS

Question 18

Answer 18

Question 19

how does mucous interact with olfactory system?

where is mucous produced in the olfactory epithelium?

what does nitric oxide do in nasal passages? where produced

Answer 19

• mucous is produced by bowmans glands in the olfactory epithelium. odorants are trapped in mucous & react with the olfactory receptors in cilia
• nitric oxide: kills inhaled pathogens. arises fom nasal sinuses

Question 20

what happens to nasal mucous once it is contanimated with dust / pathogens? (2)

Answer 20

1. swallowed: passes into the stomach - acid kills it off

2. sneeze: expels air from mouth and nose -> expels mucus

Question 21

what happens in mucous with cystic fibrosis

Answer 21

CF:

• *- mucous is abnormally thick**
• difficult for cilia to move it
• require regular physio to cough up and remove it so it doesnt become infected with pathogens

Question 22

why is there no mucuous in alveoli?

what is the last line of defence of resp. tract v pathogens?

Answer 22

• no mucous in alveolo: impede diffusion of gases into and out of the blood

- macrophages are in alveoli: engulf pathogens or dust particles

Question 23

what is partial pressure of a resp. gas?

what is the partial pressure of oxgen in trachea?

Answer 23

partial pressure of gas A: = total pressure in gas mixture x fractional concentration of A

PO2 trachea: 150 mm Hg / 20 kPa

Question 24

what is partial pressure of o2 in alveoli?
what is partial pressure of o2 in venous blood?
what does that make the pressure gradient for oxygen to enter blood?

what is partial pressure of Co2 in alveoli?
what is partial pressure of Co2 in venous blood?
what does that make the pressure gradient for Co2 to leave blood?

what does all this ^ mean regarding changing resp. rate for excreting co2 and incoming o2?

Answer 24

PaO2 in alveoli: 100 mm Hg
PaO2 in venouse blood: 40 mm Hg
pressure gradient = (100-40) 60 mm Hg

PaCO2 in alveoli: 40 mm Hg
PaCO2 in venous blood: 46 mm Hg
pressure gradient = 6 mm Hg

pressure gradient for co2 is much less: changing resp. rate can alter excretion of CO2 without significantly affecting uptake of O2.

Question 25

what drives ventilation? 02 or CO2?

Answer 25

arterial co2 drives ventilation

(not o2)

Question 26

what is hypoxaemia and hypercapnia?

what should normal partial pressure of oxygen be in arterial blood?
what is defined as below this^?

Answer 26

Hypercapnia is when there is too much carbon dioxide (CO2) in the blood

hypoxaemia: refers to the low level of oxygen in blood

normal arterial PaO2: 8kPa / 80mmHg. if below = hypoxaemia

Question 27

what is type 1 and type 2 respiratory failure?

what is each one normally due to?

Answer 27

type 1 respiratory failure: hypoxaemia (PaO2 <8kPa) without hypercapnia
- from ventilation perfusion mismatch (It is a condition in which one or more areas of the lung receive oxygen but no blood flow, or they receive blood flow but no oxygen.) - give o2 to treat

type 2 respiratory failure: hypoxaemia with hypercapnia
- from:suggests diffusion of gases in the lungs is a problem due to chronic or acute lung disease / muscle weakness

Question 28

KNOW THIS SHIT

Answer 28

resp problems are the most common reason for gp consultations

Question 29

what are social, env and occupational factors affecting resp disease?

Answer 29

• *social factors:**
• poor social housing
• smoking
• travel (TB)
• STDS & IV drug abuse
• *environmental factors:**
• air pollution
• house dust mites (asthma)
• *occupational factors:**
• dust and chemicals (like asbestosis)