Organisation of the respiratory system

Question 1

Respiration rate of a healthy adult at rest

Answer 1

4L of blood enters and leaves alveoli per minute

5L of blood flows through pulmonary capillaries (cardiac output)

Question 2

Respiration during exercise

Answer 2

airflow can increase 20 fold

blood flow 5-6 fold

Question 3

airflow structures

Answer 3

nose/mouth, external and internal nares, naso, oro and laryngopharynx, larynx, past vocal cords, trachea, r and l bronchi, lobar bronchi, segmental bronchi, sub-segmental bronchi, conduncing bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli

Question 4

division of airways beyond the larynx

Answer 4

conducting and respiratory zones

Question 5

conducting zone

Answer 5

top of trachea to beginning of respiratory bronchioles. no alveoli, no gas exchange

Question 6

respiratory zone

Answer 6

respiratory bronchioles to alveoli. gas exchange

Question 7

airborne particles

Answer 7

trapped in nasal hairs and mucus

Question 8

mucus escalator - structures, contents, function

Answer 8

epithelial surfaces of airways, down to respiratory bronchioles, contain cilia beating upwards towards pharynx. glands and individual cells secrete mucus and macrophages. particulate matter sticks to mucus and is moved to pharynx, then swallowed. keeps particulate matter and bacteria out of lungs

Question 9

effects on cilia

Answer 9

ciliary activity and number can be decreased by noxious agents, e.g. smoking - smokers cough up mucus that would usually be swallowed

Question 10

substance secreted by airway for mucus

Answer 10

airway epithelium secretes watery fluid for mucus to ride freely on

Question 11

cystic fibrosis

Answer 11

impaired production of watery fluid. mucous layer becomes thick and dehydrated, and obstructs airways.
caused by autosomal recessive mutation in epithelial chloride channel - CF transmembrane conductance regulator (CFTR). leads to problems in salt and water movement across membranes, thickened secretions and higher chance of lung infection

Question 12

responses to infection/irritation

Answer 12

constriction of bronchioles - prevents particulates and irritants from entering
macrophages engulf and destroy particles and bacteria

Question 13

pulmonary circulation - resistance (consequences)

Answer 13

vessels accompany airways and branch down into networks of capillaries supplying alveoli
low resistance compared to systemic circulation
low pressure
minimises accumulation of fluid in interstitial spaces of lungs

Question 14

changes in intrapleural pressure

Answer 14

cause lungs to move in and out during breathing

Question 15

ventilation

Answer 15

exchange of air between the atmosphere and the alveoli

Question 16

bulk flow description and equation

Answer 16

like blood, air moves from a region of high pressure to low pressure
flow = alveolar pressure - atmospheric pressure / resistance

Question 17

atmospheric pressure

Answer 17

at nose and mouth (surrounding the body)

Question 18

atmospheric pressure at sea level

Answer 18

760mmHg, decreases in proportion to an increase in altitude

Question 19

pressures during inspiration

Answer 19

alveolar pressure is less than atmospheric pressure - negative pressure gradient

Question 20

pressures during expiration

Answer 20

alveolar pressure is greater than atmospheric pressure - positive pressure gradient

Question 21

boyle’s law definition and explanation

Answer 21

in a closed system, pressure of a gas and the volume of its container are inversely proportional
increasing volume of container decreases pressure, vice versa
P1V1 = P2V2

Question 22

transpulmonary pressure

Answer 22

difference in pressure between the inside and outside of the lung

Question 23

factors affecting volume of lung

Answer 23

transpulmonary pressure

stretchability of lungs - determines how much they expand for a given change in transpulmonary pressure

Question 24

transmural pressure

Answer 24

pressure in the inside of a structure - pressure outside the structure

Question 25

pressure outside of lungs

Answer 25

intrapleural fluid pressure

Question 26

transmural pressure acting on the lungs

Answer 26

alveolar pressure - intrapleural fluid pressure

Question 27

transmural pressure acting on chest wall

Answer 27

intrapleural fluid pressure - atmospheric pressure

Question 28

muscle contraction during inspiration and its consequences

Answer 28

intercostal muscles contract and cause chest wall to expand, diaphragm contracts downwards volume of thoracic cavity increases intrapleural pressure decreases transpulmonary pressure becomes more positive alveolar pressure becomes more negative compared w/ atmospheric pressure

Question 29

pressure when there is no airflow

Answer 29

intrapleural pressure is negative | transpulmonary pressure is always positive

Question 30

forces causing intrapleural pressure to be negative

Answer 30

elastic recoil

Question 31

how are the lungs held open?

Answer 31

positive transpulmonary pressure - exactly opposes elastic recoil

Question 32

transpulmonary pressure at rest

Answer 32

4mmHg opposes inward elastic recoil of the lung

Question 33

chest wall pressure at rest

Answer 33

-4mmHg opposes outward elastic recoil of the lung

Question 34

what keeps lungs partially expanded between breaths?

Answer 34

subatmospheric negative intrapleural pressure

Question 35

why is the intrapleural pressure subatmospheric/negative?

Answer 35

as lungs tend to collapse and thoracic wall tends to expand, they move away from eachother causes an infinitesimal enlargement of fluid-filled intrapleural space between them because fluid can't expand like air, the ip is decreased

Question 36

pneumothorax

Answer 36

atmospheric air entering the intrapleural space through thoracic wall or from inside of lung. elastic recoil and surface tension cause collapse of lung intrapleural pressure increases to 0mmHg - same as atmospheric. this eliminates traspulmonary pressure

Question 37

why is transpulmonary pressure in the lung eliminated in pneumothorax?

Answer 37

the intrapleural pressure is equal to the atmospheric pressure

Question 38

why does the chest wall move outwards during pneumothorax?

Answer 38

elastic recoil is no longer opposed

Question 39

when can a pneumothorax be caused by air leaking from inside of the lung to the pleural space?

Answer 39

high airway pressure is applied during artificial ventilation of a premature infant with high lung surface tension and fragility

Question 40

why are pneumothoraces unilateral?

Answer 40

the thoracic cavity is divided into left and right sides by mediastinum