TOPIC 6 - Respiration

Question 1

What is the difference between internal and external respiration?

Answer 1

Internal = within the cell, CO2 from glycolysis and O2 consumed - oxidative phosphorylation.

External = ventilation - exchange and transport of gaseds around body.

Question 2

The lungs branch into two sections:

What is the diffrence between the conducting and respiratory zone?

Answer 2

Conducting zone = conditions the incoming air – filter, warms and humidify.
(bronchi and bronchioles)

Respiratory zone = where gas exchange takes place
(alveolar ducts and sacs)

Question 3

Describe and explain the diffrence between bronchi and bronchioles.

Answer 3

Bronhci - have cartilage - smooth muscle, mucous glands and elastic tissue.

Bronchioles - no cartilage - lined by epithelium, more smooth muscle.

Question 4

What is the air blood barrier?

Answer 4

is a ‘sandwich’ created by flattened cytoplasm of type I pneumocyte and the capillary wall.

• has large SA for gas exchange

Question 5

What is quiet inspiration?

Answer 5

• Involves the primary muscle of inspiration  The diaphragm and external intercostal
• It causes increase in thoracic and lung volume

Question 6

What is forced inspiration?

Answer 6

• Involves primary and secondary muscles
• Scalenes
• Sternocleidomastoids
• Neck and back Muscles
• Upper respiratory tract muscles.

Question 7

What is quiet expiration?

Answer 7

• A passive process using elastic recoil – no primary muscles of expiration
• External intercostal relax, recoil of lungs to original size and diaphragm relaxes.

Question 8

What is forced expiration?

Answer 8

• Uses accessory muscles

* Internal intercostals, abdominal muscles, neck and back muscles

Question 9

What happens to the forces in the lungs and chest at rest?

Answer 9

The elastic forces balance – prevent lungs collapsing and prevent chest expanding.

The pressure in the intrapleural space is less than atmospheric pressure.

Question 10

If elastic forces in the lungs are not balanced, what happens?

Answer 10

The lungs collapse = pneumothorax

Question 11

What is lung compliance and what is the equation for compliance?

Answer 11

Compliance = distensibility = measure of elasticity - the ease of the lungs and thorax expand during pressure

c = delta v
———–
delta p

Question 12

What is the effect of disease on lung compliance?

pulmonary fibrosis and emphysema

Answer 12

Low compliance = more work to inspire (pulmonary fibrosis – lung paranchyma is more rigid)

High compliance = more difficulty expiring – loss of elastic recoil (emphysema)

Question 13

What are the components of elastic recoil in the lungs?

Answer 13

Two major components are:

1. ) Anatomical component (elastic nature of cells and extracellular matrix)
2. ) Surface tension (generated at air fluid interface)

Question 14

What is Laplace’s equation and what does it show?

Answer 14

Laplace’s equation…

P = 2T/r

In the lungs, air sacs have different volumes – Laplace’s equation shows pressure in larger sacs is lower than smaller sacs, so air will flow from smaller alveoli to larger alveoli, leading to their collapse.

Question 15

What is lung surfactant and how does it arise?

Answer 15

Produced by type II pneumocytes – composesd of lipids and proteins.

Decreases surface tension = prevents alveolar collapse - (also increases compliance and maintains alveolar size)

Question 16

How are different lung volumes measured?

Answer 16

Except residual lung volume all other lung volumes are measured by a spirometer.

Question 17

What are the 2 types of dead space?

Answer 17

Anatomical dead space = volume of conducting airways.
At rest approximately 30% of inspired air volume(150ml)

Physiological dead space = volume of lungs not participating in gas exchange
– conducting zone + non-functional areas of respiratory zone
– Normally the two values are almost identical

Question 18

How is air flow into lungs proportional to pressure gradient and resistance.

Answer 18

air flow is…

^ proportional to the pressure gradient

inversely proportional to the resistance.

Question 19

What is Poiseuille’s law?

Answer 19

The impact of resistance is proportional to gas viscosity and tube length but is inversely proportional to the fourth power of the radius.

Question 20

What 3 factors impact airway resistance?

Answer 20

1. airway diameter - muscus reduces diameter and increases resistance
2. Oedema - increases resistance as fluid retention causes swelling and narrowing.
3. Airway collapse - narrow airways = increased resistance.

Question 21

How is airway diamter and the bronchial smooth controlled?

Answer 21

Parasympathetic: acetylcholine acts on muscarinic receptors = CONSTRICTION

Sympathetic: release of norepinephrine = weak agonist leads to DILATION

epinephrine = better agonist leads to DILATION

Histamine - released in inflammatory process = CONSTRICTION.

Question 22

What is Dalton’s law regarding gas pressure?

how does water vapour affect partial pressure?

Answer 22

The total pressure of a mixture of gases is the sum of their individual partial pressures.

Water vapour reduces partial pressure.

Question 23

What is Henry’s Law?

What is the equation?

Answer 23

the concentration of a gas is dissolved in a solution that can be determined.

[GAS] dis = s x P gas

s = solubility coefficient

P = gas partial pressure

Question 24

What is the structure of haemoglobin and what are the two states it exists in?

Answer 24

It has a tetrameric structure with 4 subunits. Each haem unit has a single iron atom.

Haemoglobin exits in tense and relaxed state.

• Tense = low O2 affinity
• Relaxed = high O2 affinity

Question 25

What is the effect of temperature and pH on the oxygen-dissociation curve?

what is the pH shift effect called?

Answer 25

TEMP:

high temp = down and right
low temp = up and left

pH:

high pH = up and left
low pH = down and right

Shift caused by pH is known as Bohr effect.

Question 26

How does fetal haemoglobin differ from adult haemoglobin?

Answer 26

In Fetal-Hb the β-globin chains are replaced by γ-chains. There is a leftwards shift in Hb-O2 curve – higher affinity for O2.

Question 27

What are the two types of lung disease?

Answer 27

Obstructive and restrictive.

1. Obstructive – reduction in flow through airways
2. Restrictive - Reduction in lung expansion

Both reduce ventilation

Question 28

What is obstructive lung disease?

give examples

Answer 28

a reduction in flow through air ways…

• decreases FEV1.
• the patient’s FEV1 is reduced to less than 80% of the FVC
• chronic bronchitis
• Asthma - inflammatory disease
• COPD (chronic obstructive pulmonary disease)
• Emphysema = loss of elastin (high compliance)

Question 29

What is asthma and how can it be triggered?

How is asthma treated?

Answer 29

ASTHMA = sufferers have hyper-active airways

Trigger can be:

• Atopic (extrinsic) - allergies, inghaled allergens
• Non-atopic (intrinsic) - respiratory infections, cold air, stress

Treatment: can be rapid short term or longer term.

• short acting B2 -adrenoreceptor agonists = salbutamol (dilates airways)
• Long acting B-adrenoreceptor agonists - inhaled steroids - Glucocorticoids

Question 30

What is restrictive lung disease?

Answer 30

= Reduced lung/chest expansion

• loss of compliance
• decreased FVC but FEV1 is same or even increased

Question 31

What is asbestosis?

Answer 31

slow build up of fibrous tissue that = a loss of compliance

Question 32

What are the 2 medullary centres and their function?

Answer 32

The DRG Dorsal respiratory group and the VRG Ventral Respiratory Group.

DRG = Controls Inspiration by sending signals to the inspiratory muscles.
Spontaneously active – shows period of activity – shuts off – period of activity

VRG = Controls Inspiration and expiration
Inactive during quiet respiration.
During activation helps control forceful inspiration and expiration.

Question 32

What are the 2 medullary centres?

Answer 32

The DRG Dorsal respiratory group and the VRG Ventral Respiratory Group.

Question 33

What is the role of the pons and the 2 centres which make its structure?

Answer 33

Pons has 2 centres that send stimuli to medulla to regulate breathing.

1. PNEUMOTAXIC centre - increases rate by shortening inspirations. (inhibitory effect on inspiratory centre)
2. APNEUSTIC centre - reduces rate and increases depth by prolonging inspirations. (stimulates inspiratory centre).

Question 34

What is the function of stretch recepors in the lungs?

Answer 34

send signals back to the medulla to limit inspiration and prevent over-inflation of the lungs. Example – Hering- Breuer reflex

Question 35

What are chemoreceptors (in lungs)

Answer 35

Monitor conditions in the cerbro-spinal fluid. Sensing carbon dioxide and pH.

Indirect response to a rise in CO2 - stimulation leads to an increase in ventilation.

Peripheral Chemoreceptors –
Located in the carotid body and aortic arch

Respond to
Increase in CO2
Decrease in pH
Decrease in O2

Stimulation leads to an increase in ventilation.