Week 9: Respiratory system

Question 1

The tissues comprising the respiratory tract: (6 tissues)

Answer 1

Elastic cartilage
Hyaline cartilage
Stratified squamous epithelium
Ciliated epithelium and goblet cells
Simple squamous epithelium 
Smooth muscles

Question 2

The respiratory system consists of 2 zones, the C______ zone and R_______ zone.

Answer 2

The Conducting zone
•Respiratory passageways
•Rigid conduits for the
passage of air
•Cleanse, humidifies and
warms incoming air

The Respiratory zone
•The site of gas exchange
•Respiratory bronchioles
•Alveolar ducts
•Alveoli

Question 3

the three functions of the larynx (May want to read over The conduction zone PP)

Answer 3

• Provide a patent (open) airway: Cartilage
• Switching mechanism to route air and food: Epiglottis
• Voice production: Voice box.

Question 4

The respiratory region site of gas exchange between the atmosphere and body comprises of:

Answer 4

Respiratory bronchioles
Alveolar ducts
alveolar sacs
alveoli (300 million in lungs)

Question 5

Entry and exits points of blood vessels are situated in the hilum of each lung

what is bronchial and pulmonary circulation

Answer 5

Pulmonary

• systemic venous blood that is to be oxygenated
• delivered by pulmonary arteries

Bronchial
- Bronchial arteries provide oxygenated blood to lung tissue

Question 6

Pleural membranes and pleural cavity

Answer 6

visceral pleura covers the lungs

Parietal pleura lines the ribcage and covers the upper surface of the diaphragm

pleural cavity is the potential space between the ribs and lungs

Question 7

Respiratory physiology (intro)

Answer 7

Breathing consists of two phases
Inspiration
– Expiration
• Under voluntary and involuntary control
• Short story
– Breathing is largely controlled by two sets of muscles
• Intercostal
• Diaphragm muscles

Question 8

Expansion, atmospheric pressure in lungs??

Answer 8

Atmospheric pressure (atm)
– Pressure exerted by the air surrounding the
body (at sea level 760mm Hg or 1 atm)
– A respiratory region that has pressure lower
than 1atm = Negative respiratory pressure
– A respiratory region that is equal to 1 atm has
Zero respiratory pressure
• Intrapulmonary Pressure
– Pressure inside the alveoli
• Intrapleural Pressure
– Pressure between the two pleura

Question 9

Events of inspiration and experation

Answer 9

found on PP slides 9 10 Respiratory physiology

Question 10

Gas exchange in the lungs

Answer 10

Movement of gases across the respiratory membrane is by diffusion.
• Dependent upon partial pressure of each gas
– partial pressure is equivalent to gas “concentration”.

Relative solubilities of gases in water are also important
CO2 is approx. 20 times more soluble in water than O2

So….. the majority of CO2 is carried by the plasma, whereas the
majority of O2 is carried by haemoglobin in erythrocytes (RBC’s).

NOTE: The atmosphere contains mostly
Nitrogen but it is practically insoluble at 1 ATM

Question 11

Daltons law of partial pressures

Answer 11

Slide 3 physiology of oxygen PP

Dalton’s law of partial pressures states that in a mixture of gases the pressure exerted by each gas is the same as that which it would exert if it alone occupied the container.

Question 12

Gas exchange: What is partial pressure?

Answer 12

Air pressure (sea level) = 760 mm Hg
• Gas concentrations in air: 21% oxygen, 0.04% carbon dioxide
• Partial pressure of oxygen in air (PO2):
= 21% x 760 mm Hg
= 159 mm Hg
• Partial pressure of carbon dioxide in air (PCO2):
= 0.04% x 760 mm Hg
= 0.3 mm Hg
Partial pressure: Pressure exerted by each gas is directly
proportional to the % of that gas in the gas mixture.

Question 13

Gas transport

Answer 13

Oxygen:
– majority bound to heme in haemoglobin of RBCs
– binding dependent on partial pressure PO2 (O2 concentration)

Question 14

Haemoglobin

Answer 14

Heme: iron-containing pigment

• Globin: four protein (2 alpha + 2 beta) sub-units (each containing 1 heme molecule)
• Four (4) molecules of oxygen carried per molecule of haemoglobin
• The process of oxygen loading is rapid and reversible.

Each iron-containing
heme group
carries one O2
molecule
ONE red blood cell
~ 250 million Hb molecules
~ 1 billion O2 molecules!!!

Question 15

Gas transport (More in depth)

Answer 15

Carbon dioxide:
– mainly (~70%) as soluble bicarbonate (HCO3
-
) ions in
plasma
• carbonic acid-bicarbonate buffer system maintains blood pH
• CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3
-
• enhanced by carbonic anhydrase (enzyme in RBCs)
– some (20-30%) bound to haemoglobin
• not bound to heme, but to globin protein subunits instead
• forms carbamino-haemoglobin
– some (7-10%) simply dissolved in plasma

Question 16

Rate at which haemoglobin binds or

releases O2 is regulated by:

Answer 16

PO2 (the relative concentration of O2)
• Temperature
– increased temp. aids oxygen release
• Blood pH
– acid pH weakens Hb-O2 bond
→ O2 release enhanced (and uptake decreased)
→ O2 is released at the tissues (where it is needed)
• P CO2 (the relative concentration of CO2)
• Presence and concentration of some proteins in the blood
– BPG aids O2 release

Question 17

The Bohr Effect (Slide 5 Physiology of carbon dioxide)

Answer 17

The effect of acidic pH
and PCO2 of the blood
on oxygen-haemoglobin
saturation……

Question 18

Rate and depth of
respiration are
controlled by:

Answer 18

Hypothalamus
– pain, emotions
• Brain stem
– pons
– medulla oblongata
• Chemoreceptors
– central
– peripheral
• Stretch receptors
– in lungs

Question 19

Brain Stem Control of Respiration

Answer 19

The Medulla Oblongata:
(Medullary rhythmicity area)

•Ventral Respiratory Group
– Inspiration and Expiration
•Dorsal Respiratory Group
– Integrates input from
stretch and chemoreceptors

The Pons:
•Pontine Respiratory Centres
– Modifies the breathing
rhythms (vocalisation, sleep
and exercise)