Physiology 2058 Respiratory

Question 1

Bronchioles

Answer 1

Smooth muscle, diameter alters, SNS controls

Question 2

Pulmonary ventilation

Answer 2

mechanics of breathing, air from higher pressure area to lower pressure area, causes changes in volume of the lungs

Question 3

Mechanics of breathing

Answer 3

inspiration- diaphragm contracts, volume of thorax increases and pressure within it falls, air to flow from outside into lungs
expiration- process reversed, aided by elastic recoil, passive

Question 4

Lung compliance

Answer 4

Ease of lung expansion, healthy- highly compliant, for a given change in pressure, large change in volume, reduces WOB
over- compliant- emphysema
under - compliant - fibrosis
increase air way resistance reduces air flow- hard to breath

Question 5

Surfactant

Answer 5

liquid produced by certain alveolar cells and lines in inner surface of alveoli, begins in utero, reduces surface tension, keeps airways open increasing compliance, in RDS preterm infants lack of surfactant increasing WOB

Question 6

Lung volume and capacities

Answer 6

Measured using spirometry, varies, tidal volume, inspiratory reserve volume, expiratory reserve volume, functional residual capacity, vital capacity, residual volume

Question 7

Tidal volume

Answer 7

volume of air moved in and out of lungs during a normal breath - minute volume= TV x RR

Question 8

Expiratory reserve volume ERV

Answer 8

volume of extra air breathed out after normal expiration

Question 9

Inspiratory reserve volume IRV

Answer 9

volume of extra air breathed in after normal inhalation

Question 10

Functional residual capacity FRC

Answer 10

The volume of air in the lungs after a normal exhalation

Question 11

Residual volume

Answer 11

Total volume of air left in lungs after maximum exhalation

Question 12

Vital capacity

Answer 12

Maximum amount of air that can be moved in and out of the lungs in a single breath

Question 13

Forced vital capacity

Answer 13

speed is important, peak flow meter

Question 14

Atmospheric pressure

Answer 14

Air as gases, nitrogen, oxygen , carbon dioxide and water vapour exerting certain amount of total

Question 15

Partial pressure

Answer 15

Each gas exerts an individual partial pressure

Question 16

Inhaled air partial pressures

Answer 16

Nitrogen 79%, oxygen 20.9%, CO2 20.9%, water vapour .5%

Question 17

Alveolar Air

Answer 17

Nitrogen 75.4%, Oxygen 13.2%, CO2 5.2%, Water vapour 6.2%

Question 18

Gas exchange

Answer 18

diffusion, intimate relationship between alveoli and pulmonary capillaries, pulmonary vascular resistance is low facilitating good lung perfusion

Question 19

Criteria for Gas exchange across the resp membrane

Answer 19

Factors influencing diffusion- SA available, thickness of resp membrane (0.5microns), partial pressure gradient of the gases, lipid solubility of the gases, good ventilation/perfusion needed

Question 20

Pulmonary gas exchange

Answer 20

O2 diffuses down conc gradient across resp membrane from alveoli to pulmonary capillaries, around circulation bound to haemoglobin, small amount dissolved in plasma
CO2 diffuses down conc gradient across resp membrane from pulmonary capillaries into alveoli to be expelled

Question 21

O2 transport in blood

Answer 21

bound to haemoglobin, oxyhaemoglobin - reversible rxn, some dissolved in blood - partial pressure of O2, normal PO2 of arterial blood is 95-100mmHg, when blood reaches tissues, oxygen is released from Hb and diffuses into cells
Amount of O2 bound to Hb is influenced by PCO2, blood Ph, Temp

Question 22

Internal respiration

Answer 22

involves the diffusion of O2 acorss the capillary membrane into the cells

Question 23

CO2 transport in blood

Answer 23

23% as carbaminohemoglobin- venous side of circulation
70% as bicarbonate ions, through formation of carbonic acid
Small amount dissolved in plasma

Question 24

The resp centre

Answer 24

Medulla oblongata and Pons of brainstem, basic rhythm set by rhytmicity centre - involuntary
Inspiratory area- dorsal respiratory group neurones
Expiratory area- ventral respiratory group neurones

Question 25

Role of Chemoreceptors in Control of ventilation/ breathing

Answer 25

Central and peripheral, high blood supply
Central- detect changes in PCO2; H+
Peripheral- detect changes in PCO2, H+, and PO2 levels (only peripheral detect changes in PO2)

Question 26

Hypercapnia

Answer 26

Increase in PCO2 levels in blood

Question 27

Hypocapnia

Answer 27

Decrease in PCO2 levels in blood

Question 28

Hyperventilation

Answer 28

Increase in rate and depth of breathing

Question 29

Arterial blood gases

Answer 29

PO2, PCO2, pH, HCO3-

Question 30

What drives minute to minute breathing

Answer 30

PCO2 more powerful effect, as PCO2 increases, Ph decreases, blood more acidic normal blood 7.37-7.45

Question 31

O2 levels fall

Answer 31

powerful stimulatory effect on ventilation mediated by peripheral chemoreceptors

Question 32

Hypoxia

Answer 32

Lack of O2 in blood in hypoxaemia, leads to tissue hypoxia, lack of o2 to cells

Question 33

Cyanosis

Answer 33

dusky blueish seen in extremities and mucosa, build up of deoxyhemoglobin in blood

Question 34

Hypoxic hypoxia

Answer 34

decreased ability to oxygenate the blood, decrease in arterial PO2 (normal 95-100mmHg)

Question 35

Causes of hypoxic hypoxia

Answer 35

High altitude - reduced O2 levels in atmosphere, hyperventilates to improve oxygenation to blood
Hypoventilation- sufficient O2 in atmosphere but can’t oxygenate their blood properly COPD
Ventilation/ perfusion problems - match good ventilation of alveoli with normal perfusion of lung capillaries to that blood leaving is well oxygenated

Question 36

Types of hypoxia

Answer 36

Hypoxic hypoxia, Anaemic hypoxia, Stagnant/ishcaemic hypoxia, hystotoxic hypoxia

Question 37

Anaemic hypoxia

Answer 37

Anaemic hypoxia - PO2 normal but low Hb levels reduce ability to carry O2

Question 38

Stagnant/ ishcaemic hypoxia

Answer 38

PO2 normal, Hb normal, reduced blood supply to an organ

Question 39

Histotoxic hypoxia

Answer 39

Cells can’t use oxygen available to them, mitochondrial poisoning, cyanide gas- pesticides