5. Respiratory Physiology

Question 1

What is Cellular Respiration?

Answer 1

Metabolic processes use O2 to produce CO2, they derive energy from nutrient molecules

Question 2

What does the Respiratory Quotient (RQ) mean?

Answer 2

Ratio of CO2 produced to O2 consumed. Vaires depending on foodstuff consumed.

Question 3

What is External Respiration?

Answer 3

Exchange of O2 and CO2 between environment and organism.

Question 4

Name the 4 steps of External Respiration.

Answer 4

Ventilation, O2 and CO2 exchange between air in alveoli an blood in capillaries, Transport of O2 and CO2 in blood to tissues, and excahnge between tissues and blood

Question 5

What is an airway?

Answer 5

Pathway of air into lungs

Question 6

Describe the structure of Trachea and Bronchi

Answer 6

Rigid tubes, rings of cartilage to avoid collapsing.

Question 7

Describe the structure of Bronchioles

Answer 7

No cartilage, walls contain smooth muscle (autonomic NS). Sensitive to certain hormones and chemicals

Question 8

Describe the structure of Alveoli

Answer 8

Thin Walled inflatable sacs. The site of Gas Exchange.

Question 9

What is the difference between Type 1 and Type 2 alveolar cells.

Answer 9

Type 1 is one cell thick, short diffusion distance. Type 2 secretes surfactant

Question 10

What is the role of Alveolar macrophages and the Pores of Kohn?

Answer 10

Macrophages guard lumen and pores allow airflow between neighbouring alveoli (collateral ventilation)

Question 11

Name 3 features of alveoli that make it effective for its function.

Answer 11

Large surface area, thin walls (one cell thick) and surrounded by capillary vessels. (increase diffusion)

Question 12

What is the diaphragm made from?

Answer 12

Smooth muscle

Question 13

What is the role of the Diaphragm?

Answer 13

Separates thoracic cavity from abdominal cavity.

Question 14

What is the pleural sac?

Answer 14

Double-walled, closed sac separating each lung from theoracic wall.

Question 15

What is the pleural cavity.

Answer 15

Area which surrounds the lung. It allows room for the lungs to expand and contract, and is designed to make it easy for the lungs to inflate after they have deflated

Question 16

What is the function of intrapleural fluid?

Answer 16

Secreted by surfaces of the pleura and it protects the lung from damage.

Question 17

Name the 4 primary functions of respiratory system.

Answer 17

Exchange of gases between air and blood, homeostatic regulation of body pH, defence against inhaled pathogens and irritating substances (cilia, Mucus escalator and macrophages), and vocalisation.

Question 18

Name the three pressures to consider in the respiratory system.

Answer 18

Atmospheric, Intra-alveolar and intrapleural pressure.

Question 19

If alveolar pressure is greater than atmospheric pressure, where does the air go?

Answer 19

Flows out of lungs to the environment.

Question 20

What is Boyle’s Law?

Answer 20

At any constant temperature, pressure exerted by a gas vaires inversely with the volume of a gas. Change in lung size changes pressure.

Question 21

What is the transpulmonary pressure?

Answer 21

Pressure inside the lungs minus the pressure in the intrapleural fluid (outside lungs)

Question 22

Name the nerves that the diaphragm and intercostal muscles are innervated by.

Answer 22

Diaphragm: Phrenic Nerve

Intercostal muscles: Intercostal nerve.

Question 23

What happens to the diaphragm during inspiration which allows air to enter lungs?

Answer 23

Diaphragm contracts and flattens to lower the volume of the intrapleural pressure. The lungs expand into this area of lower pressure which increases the volume of the lungs and lowers intra-alveolar pressure below the atmospheric pressure so air move in.

Question 24

Other than the diaphragm, what other structures further enlarge the thoracic cavity which further increases the volume of the lungs.

Answer 24

Contraction of accessory inspiratory muscles.

Question 25

What decreases the size of the chest cavity during expiration?

Answer 25

Relaxation of inspiratory muscles, diaphragm and muscles of the chest wall. Elastic recoil of the alveoli.

Question 26

What happens to the intrapleural pressure during expiration?

Answer 26

Increases

Question 27

What happens during forced expiration?

Answer 27

Internal intercostal muscles contract to further reduce the volume of the lungs to force more air out of the lungs.

Question 28

What is compliance?

Answer 28

Effort needed to stretch lungs. The change in volume due to a given force or pressure. -V/P

Question 29

What causes recoil?

Answer 29

Highly elastic connective tissue in lungs. Alveolar surface tension.

Question 30

What is the function of the surfactant?

Answer 30

Produced by type 2 alveolar cells. Contain phospholipid molecules which lowers surface tension of liquid lining alveoli so pressure needed to hold alveoli open is reduced.

Question 31

What is the law of LaPlace?

Answer 31

P = 2T/R

Question 32

What is the main determinant of airway resistance?

Answer 32

Diameter of conducting airway.

Question 33

What can mucus accumulation cause?

Answer 33

Increased resistance

Question 34

What affect does the collapsible tubes of the Bronchioles have on the airway resistance?

Answer 34

Increases airway resistance.

Question 35

What other factors increase airway resistance?

Answer 35

Large lengths of system and high viscosity of substance flowing.

Question 36

Define tidal volume

Answer 36

Volume of air per breath (500ml)

Question 37

Define Inspiratory Reserve

Answer 37

Extra Volume that can be max inspired. (3000ml)

Question 38

How do you work out Inspiratory capacity?

Answer 38

Tidal Volume + Inspiratory Reserve (3500ml)

Question 39

Define Expiratory Reserve

Answer 39

Extra Volume that can be expired by maximal contraction beyond normal. (1000ml)

Question 40

Define Residual Volume.

Answer 40

Minimal volume remaining in lungs after maximal expiration. (1200ml)

Question 41

Define Functional Residual Capacity.

Answer 41

Volume of air in lungs at end of normal expiration. (Expiratory Reserve + Residual Volume) (2200ml)

Question 42

Define Vital Capacity

Answer 42

Maximum volume of air moved in a single breath after maximum inspiration. (Inspiratory reserve + Tidal Volume + Expiratory Reserve) (4500ml)

Question 43

Define Total Lung Capacity.

Answer 43

Maximum volume that the lungs can hold. (Vital Capacity + Residual Volume) (5700ml)

Question 44

Define Forced Expiratory volume in 1 sec

Answer 44

Volume of air can be expired during the first second of expiration in a vital capacity determination.

Question 45

How do you work out Minute Ventilation?

Answer 45

Tidal Volume x Respiratory Rate.

Question 46

What is dead space?

Answer 46

Air that fills the conducting respiratory passageway and never contributes to gas exchange

Question 47

What is Alveolar dead space?

Answer 47

Inspired fresh air not used for gas exchange with the blood even though it reaches alveoli.

Question 48

How do you work out alveolar ventilation?

Answer 48

(Tidal Volume - Dead Space) x Respiratory Rate.

Question 49

Is the concentration of O2 and CO2 in arterial blood relatively constant?

Answer 49

Yes,

Question 50

How does O2 and CO2 move during gas exchange?

Answer 50

Simple Diffusion

Question 51

How would you work out the partial pressure exerted by each gas in a mixture?

Answer 51

Total Pressure x Fractional Composition of Gas in Mixture.

Question 52

What affects diffusion gradients?

Answer 52

Size of concnetration gradient, surface area and permeability

Question 53

What is Daltons Law?

Answer 53

It shows that all the individual pressures add together to give the total pressure.

Question 54

What percentage of the total composition is oxygen in the atmosphere?

Answer 54

21%

Question 55

Does O2 move in or out of the body?

Answer 55

In

Question 56

Is the concentration of CO2 greater in the alveoli or blood?

Answer 56

In blood.

Question 57

Describe the concentrations of O2 and CO2 in the blood leaving tissue Cells

Answer 57

Low O2 and high CO2

Question 58

What gas makes up the majority (79%) of atmospheric air?

Answer 58

Nitrogen Gas

Question 59

Is CO2 more or less soluble in blood compared to O2?

Answer 59

More

Question 60

The amount of gas that dissolves in a liquid depends on what two factors?

Answer 60

Solubility of the gas in the liquid and the partial pressure of the gas.

Question 61

Which gas exchanged has a partial pressure of 0.23mmHg in Air and 40mmHg in Alveoli?

Answer 61

CO2

Question 62

Name the 3 factors that determines alveolar partial pressure.

Answer 62

PO2 and PCO2 Inspired Air, Minute Ventilation, and Rate of respiring tissue to consume O2 and produce CO2

Question 63

Describe the partial pressures of O2 and CO2 when alveolar evnt exceeds demands of tissue.

Answer 63

Higher PO2 and Lower PCO2

Question 64

What does the ventilation perfusion (VA/Q) relationship show?

Answer 64

Ratio of alveolar ventilation to pulmonary blood flow.

Question 65

Is there a higher VA/Q at the base or apex of the lung?

Answer 65

Apex

Question 66

Does blood flow or ventilation decrease 3x faster?

Answer 66

Blood Slow

Question 67

VA/Q is highest when?

Answer 67

Max Ventilation and no perfusion.

Question 68

What is the VA/Q when there is an airway obstruction?

Answer 68

Zero, Blood gas content remains unchanged during passage through capillary.

Question 69

What is the Normal VA/Q?

Answer 69

0.8

Question 70

What causes infinite VA/Q?

Answer 70

Vascular Obstruction: Alveolar gas remains at atmospheric levels.

Question 71

What molecule carries oxygen in blood?

Answer 71

Haemoglobin

Question 72

How many O2 can Haemoglobin carry at once?

Answer 72

4 due to its 4 haem groups.

Question 73

Name the 2 methods of transport for O2 in blood.

Answer 73

Bound to haemoglobin (98.5%) and Dissolved (1.5%)

Question 74

Name the 3 methods of transport for CO2 in blood

Answer 74

Bound to Haemoglobin (30%), Dissolved (10%) and as bicarbonate (60%)

Question 75

In what cells are haemoglobin found?

Answer 75

Erythrocytes (red blood cells)

Question 76

The percentage saturation is high when what?

Answer 76

Partial Pressure is high.

Question 77

Where is the % saturation high?

Answer 77

Lungs

Question 78

What happens at low % saturations due to low partial pressure of oxygen?

Answer 78

Dissociation of Oxygen into tissues.

Question 79

What does the steep part of a oxygen dissociation curve represent?

Answer 79

Represents the ease of the 2nd and 3rd O2 molecules in attaching to haemoglobin. The shallow parts represent the difficulty of O2 binding.

Question 80

What sort of curve is the oxygen dissociation curve?

Answer 80

Sigmoidal.

Question 81

What does the binding of the 1st O2 to haemoglobin cause?

Answer 81

Induces conformational change to make it easier for the next O2 to bind, increasing affinity.

Question 82

Does O2 associate or dissociate at high O2 affinity of haemoglobin?

Answer 82

Associate

Question 83

Why is it hard for the last O2 molecule to bind to a haemoglobin?

Answer 83

PO2 above 60 mmHg results in there being few binding sites avaliable left.

Question 84

How saturated is haemoglobin at the systemic veins and respiring tissue?

Answer 84

75%

Question 85

What is the benefit of there being still loads of O2 molecules in haemoglobin when it reaches respiring tissue.

Answer 85

Huge capacity to unload more O2 if tissue metabolism increases (e.g. during exercise).

Question 86

Does increased affinity for oxygen cause a leftward or a rightward shift of the oxygen dissociation curve?

Answer 86

Leftward shift - Lower PO2 required to achieve a given O2 saturation - loading more efficient.

Question 87

Does increased temperature cause a leftward or a rightward shift of the oxygen dissociation curve?

Answer 87

Rightward Shift - Higher PO2 required to achieve a given O2 saturation - unloading more efficient.

Question 88

Does increased acidity decrease or increase the affinity of haemoglobin for O2?

Answer 88

Decrease - Respiring tissue produce H+ to facilitate unloading.

Question 89

What effect does 2,3-DPG have on the dissociation curve?

Answer 89

Added DPG (produced during glycolysis) causes more unloading due to lower affinity. (right shift)

Question 90

Describe the structure of Myoglobin.

Answer 90

O2 binds to myoglobin's single haem group. Found in skeletal muscle. Liberates O2 when PO2 down to 10mmHg. At low PO2, it is 50% saturated.

Question 91

What is the difference between adult and foetal haemoglobin?

Answer 91

Foetal Hb has a greater affinity for O2 than adult and has a slightly different structure.

Question 92

What buffers H+ ions produced by the formation of bicarbonate ions from CO2

Answer 92

Haemoglobin.

Question 93

What is exchanged with HCO3- to allow it to enter the plasma?

Answer 93

Cl-

Question 94

What are the two products made from the reverse of the carbonic acid reaction?

Answer 94

Water and CO2

Question 95

What catalyses the formation of carbonic acid from CO2 and H20?

Answer 95

Carbonic Anhydrase

Question 96

The removal of oxygen from haemoglobin at tissue cells increases what?

Answer 96

The ability of Haemoglobin to bind with CO2

Question 97

Difference between Haldane and Bohr Effect

Answer 97

Haldane: Promote loading CO2 Bohr: Promote unloading O2

Question 98

What effect does hypoventilation have on PCO2 and pH

Answer 98

Increases PCO2 and Lowers pH due to increased bicarbonate and H+

Question 99

What does the kidney do during respiratory acidosis?

Answer 99

Conserves more HCO3- to act as a buffer

Question 100

What does the kidney do during respiratory alkalosis?

Answer 100

Excretes HCO3- to reduce concentration of buffer

Question 101

What is hypoxia?

Answer 101

Lack of O2 availability in tissues

Question 102

What is Hypoxemia?

Answer 102

Relative deficiency of O2 in blood.

Question 103

What is Dysoxia?

Answer 103

Lack of O2 utiilisation by tissues.

Question 104

What is chronic bronchitis?

Answer 104

Inflammation in lungs causes large amounts of mucus production

Question 105

What are the 2 effects of increased mucus?

Answer 105

Blockage of bronchioles and creates a breeding ground fro bacteria

Question 106

What is emphysema?

Answer 106

Persistant coughing causes stiff tissues and structural damage. Leads to less functional alveoli available

Question 107

What do central chemoreceptors detect?

Answer 107

H+ ions

Question 108

What do peripheral chemoreceptors detect?

Answer 108

O2, CO2 and H+ ions

Question 109

Which intercostal muscles are involved in inspiration?

Answer 109

External Intercostal Muscles

Question 110

What do pulmonary receptors detect?

Answer 110

Stretch

Question 111

What controls inspiration and expiration?

Answer 111

Respiratory neurons in medulla.

Question 112

What modulates ventilation?

Answer 112

Neutrons in pons and chemical factors

Question 113

What are the 2 cell groups of medulla oblongata?

Answer 113

Dorsal respiratory group and ventral respiratory group.

Question 114

What is the role of the dorsal respiratory group?

Answer 114

Inspiration neurons control external intercostal muscles and diaphragm

Question 115

What is the role of the ventral respiratory group?

Answer 115

Neurons control muscles for active expiration and for greater-than-normal inspiration.

Question 116

What alters dorsal and ventral respiratory groups activity?

Answer 116

Inputs via vagus nerve plus higher brain centres.

Question 117

Does the activity of inspiratory neurons follow a negative or positive feedback mechanism?

Answer 117

Positive feedback mechanism

Question 118

Does activation of chemoreceptors lead to increased or decreased ventilation?

Answer 118

Increased ventilation

Question 119

Can H+ cross blood brain barriers?

Answer 119

No

Question 120

What effect does hypoventilation have on breathing rate and depth?

Answer 120

Increases them due to high PCO2 stimulating chemoreceptors.