MBCHB 221A Lecture Notes - Lecture 2: Mucus, Viscosity, Spirometer

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coralmule555

2 Jun 2018

School

University of Auckland

Department

MBChB

Course

MBCHB 221A

Professor

Dennis

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Airways and Anatomic Dead Space:

1. The airways consists of branching tubes

2. The trachea divides into the left and right main bronchi → lobar bronchi (2 lobar

bronchi- left and 3 lobar bronchi- right) → segmental bronchi- which then continue

dividing into → terminal bronchioles (about 16 branches until first alveoli appear)

• Terminal bronchioles – smallest airways without alveoli

• All these bronchi make up the conducting airways – Function: Lead inspiring

air into the gas-exchanging regions of the lung

3. Conducting airways have no alveoli- hee do’t take pat i gas ehage → the

volume in the conducting airways is the anatomic dead space (Volume = 150 ml)

4. Respiratory zone – the area where gas exchange occurs.

• Made up of respiratory bronchiole (occasional alveoli budding on its wall)

→alveolar ducts (ducts completely lined with alveoli) → alveolar sacs →

alveoli

• Respiratory zone makes up most of the volume of the lung at rest – about 2.5

to 3 litres (at rest). Volume at rest (at FRC) is about 2.5 to 3 litres.

5. The portion of the lung distal to a terminal bronchiole forms an anatomical unit –

acinus.

6. The conducting airways extend to the terminal bronchiole and their total volume

is about 150 ml (which is also the anatomic dead space).

7. All gas exchange occurs in the respiratory zone, which has a combined volume of

2.5 to 3 litres.

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8. Convective flow is the main respiratory mechanism until the terminal bronchioles,

beyond the terminal bronchioles, diffusion of gases becomes the main respiratory

mechanism.

Functional zone:

Structure:

Generation:

Function:

Conducting

Zone:

Trachea

Passage for air to flow through.

Main stem bronchi

(Primary left and

right bronchi)

Supplies each lung

- The right main bronchus is

more vertical, shorter, and

wider than the left. As a

result, an aspirated object is

more likely to enter and

lodge in the right main

bronchus than the left.

Lobar bronchi

(Secondary

bronchi)

- supply the lobes (the left

lung has two lobes while the

right lung has three lobes)

Segmental bronchi

(Tertiary bronchi)

- supply the specific

bronchopulmonary

segments within the lobes

of the lung

- 8 segments on the left and

10 segments on the right

Smaller bronchi

4-9

Bronchioles

10-15

Bronchioles in turn branch

repeatedly into terminal

bronchioles

Terminal

bronchioles

16-19

The last bronchiole in the

conducting zone

- Terminates the conducting

zone

- Last structure that is

involved in air conducting

and last structure that is not

involved in gas exchange

- Terminal bronchioles

represent the end of the

conducting zone of the

respiratory system.

Respiratory zone

Respiratory

bronchioles

20-23

Alveolar ducts

24-27

Alveolar sacs

Velocity of air within the airways:

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1. During inspiration- the diaphragm contracts, descends and flattens, the external

intercostal muscles contract while the internal intercostal muscles relax to raise the

ribs and expand the chest cavity by increasing the cross sectional area of the thoracic

cavity to increase the volume of the thoracic cavity and decrease the pressure in the

thoracic cavity.

• Thus air moves into the terminal bronchiole by bulk flow.

• Beyond the terminal bronchiole, the total/combined cross sectional area of

the respiratory airways increases and is extremely large. Hence the forward

velocity of the gas during inspiration decreases tremendously in the region of

the respiratory bronchiole. Thus gaseous exchange becomes the chief mode

of ventilation.

• → As a consequence of the velocity of air dropping tremendously at the level

of the terminal bronchiole – inhaled dust frequently settles out there.

• The difference in concentration within the acinus is abolished within a second

because of

→ The rate of diffusion of the gases within the airways is rapid

→ The distance to be covered is so short.

2. The lung is highly elastic – its can return passively to its preinspiratory volume

during resting breathing and is very easy to distend (requires a low distending

pressure) and small pressure to move gas through the airways.

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Related Questions

1. Match the word 1-39 above, with the descriptions labled a-t. Word 1-39 can be uses only one please!!

1. alveolar macrophages 2. alveoli 3. Bohr effect 4. bronchi 5. bronchiole 6. cerebral cortex 7. chloride shift 8. compliance 9. costal breathing 10. Daltonâs law 11. diaphragmatic breathing 12. epiglottis 13. eupnea 14. expiratory reserve volume 15. fauces 16. functional residual capacity 17. Haldane effect 18. Henryâs law 19. hilum 20. hypothalamus 21. inferior, middle, and superior nasal meatuses 22. inspiratory capacity 23. larynx 24. limbic system 25. medulla oblongata 26. nose 27. paranasal sinuses 28. pharynx 29. pleural membranes 30. pons 31. primary bronchus 32. secondary bronchus 33. surface tension 34. surfactant 35. terminal bronchiole 36. tertiary bronchus 37. total lung capacity 38. trachea 39. vital capacity

a) -------------------- serves as a sound resonating chamber; contains tonsils; directs air inferiorly

b) ------------------- passes air from pharynx into windpipe; site of sound production

c) ------------------ resonate(s) sound; not part of pharynx

D) ------------------ opening from oral cavity into pharynx

E) ----------------- carries air to a segment of a lung

F) -------------------- carries air directly into a respiratory bronchiole

G) ----------------- surround the lungs

H) ------------------ reduces surface tension at sites of gas exchange

i) -------------------- actual sites of gas exchange

j) --------------------- normal, quiet breathing

k) ----------------------- shallow breathing using just the external intercostal muscles

l) ------------------ amount of effort required to expand the lungs and chest wall

m) ------------------- tidal volume + inspiratory reserve volume, usually about 3600 mL in males

n) ----------------- tidal volume + inspiratory reserve volume + expiratory reserve volume; usually about 4800 mL in males

o) ------------------- residual volume + expiratory reserve volume; usually about 2400 mL in males

p) -------------------- states that the amount of gas that will dissolve in a liquid is proportional to the partial pressure of that gas and its solubility

q) ---------------- when pH decreases, O₂ saturation of hemoglobin decreases

r) ------------------ each gas in a mixture of gases exerts its own partial pressure

s) ------------------- sets basic rhythm of breathing

t) ------------------------ includes the pontine respiratory group

skywasp336

True of False: Freshwater environments have a higher concentration of oxygen than saltwater environments.

QUESTION 2 If the difference in partial pressure of gas on either side of the barrier to diffusion is 0, which of these events will occur?

The area for gas exchange will increase to accommodate this similarity.

The constant for diffusion will decrease.

The rate of diffusion will be 0.

The distance thickness of the barrier to diffusion will also be 0.

QUESTION 3 On the x-axis of the oxygenâhemoglobin equilibrium curve is the partial pressure of oxygen in tissues. Which type of blood is most likely to be represented by the right-hand side of the axis? (Hint: the oxygen-hemoglobin equilibrium curve is figure 45.14 in your book on pg 913)

blood found in the left ventricle

blood found in the right atrium

blood found in the superior vena cava

blood found in the inferior vena cava

QUESTION 4 Which of these is an example of pulmonary circulation?

Blood is pumped from the right ventricle to the lungs.

Blood is pumped from the left ventricle to the aorta.

Blood is pumped from the aorta to the cardiac vein.

Blood is pumped from the inferior vena cava to the right atrium.

QUESTION 5 O2 will diffuse from blood to tissue faster in response to which of the following conditions?

an increase in the PO2 of the tissue

a decrease in the PO2 of the tissue

an increase in the thickness of the capillary wall

a decrease in the surface area of the capillary

QUESTION 6 Which of the following promotes oxygen release from hemoglobin?

a decrease in temperature

a decrease in carbon dioxide levels

a decrease in pH

a decrease in carbonic anhydrase

QUESTION 7 How does the medulla oblongata sense the amount of carbon dioxide in the blood?

A. Carbonic anhydrase produced by cells performing cellular respiration is exported and travels though the blood, and binds to a receptor on the medullary respiratory center, which causes a signal amplification resulting in a change in gene expression which results in the production of proteins that will cause the diaphragm to contract

B. CO2 produced by cells performing cellular respiration reacts with blood plasma for form an acid, which increases the pH of the blood, which causes the medullary respiratory center to contract the diaphragm

C. CO2 produced by cells performing cellular respiration reacts with blood plasma for form an acid, which decreases the pH of the blood, which causes the medullary respiratory center to contract the diaphragm

D. A and B

E. A and C

QUESTION 8 Which of the following parts of the lung are considered "dead space"? A. The alveoli B. The trachea C. The bronchi D. B and C E. All of the above

QUESTION 9 Which of the following blood vessels have the thinnest walls?

arteries

arterioles

capillaries

venules

veins

QUESTION 10 How does the interstitial fluid return to the bloodstream?

A. Interstitial fluid flows into the capillary where the osmotic pressure driving fluid into the bloodstream is greater than the blood pressure driving fluid out of the blood

B. Interstitial fluid flows into the capillary where the blood pressure driving fluid into the bloodstream is greater than the osmotic pressure driving fluid out of the blood

C. Interstitial fluid leaves the tissue via lymphatic ducts and travels through the lymphatic system, which returns the fluid to the veins. D. A and C

E. B and C

QUESTION 11 True or False: When an electrocardiogram (EKG or ECG) shows a flat line (aka asystole), medical personnel will restart the heart using a defibrillator.

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MBCHB 221A Lecture Notes - Lecture 2: Mucus, Viscosity, Spirometer

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