Respiratory System

Question 1

what is external respiration ?

Answer 1

• the actual act of breathing

Question 2

what is internal respiration ?

Answer 2

• cellular respiration

Question 3

what structures does the upper respiratory system involve ?

Answer 3

• nose + nasal sinuses
• nasopharynx
• pharynx
• larynx

Question 4

what structure does the lower respiratory system involves ?

Answer 4

• trachea
• bronchi
• bronchioles
• alveoli

Question 5

5 function of the respiratory system (POSHG) ?

Answer 5

• gas exchange = absorption of oxygen excretion of carbon dioxide
• olfaction = specialist nerve endings in the nasal cavity + transmitted to the brain via the first cranial nerve
• speech = via vocal chords in the larynx
• homeostasis = via the oxygen + carbon dioxide exchange
• protection = via the immune system + mucus production

Question 6

what is the function of the nose in the respiratory system ?

Answer 6

• an organ of the smell
• air the warmed and filtered
• lined by epithelial cells with tiny hairs which filter incoming air
• epithelial cells secrete fluid to trap dust + bacteria, preventing it from entering lungs

Question 7

location + function of nasopharynx?

Answer 7

• lies behind the nose, continues to warm air
• have adenoids at the back - made of dense lymphoid tissue + fight infections
• eustachian tubes connect the nasopharynx to the middle ear = equalises pressure in ear

Question 8

location + function of the pharynx ?

Answer 8

• lies behind mouth + between nasopharynx + larynx
• both air and food passage
• has tonsils at the back (made of dense lymphoid tissue )
• also continue warming air

Question 9

function of the larynx ?

Answer 9

• connects pharynx to trachea
• rigid walls
• contains vocal chords
• glottis = opening from pharynx to larynx
• epiglottis = closes glottis to prevent chocking

Question 10

function + structure of trachea

Answer 10

• 20 ‘C’ shaped cartilage rings + smooth muscle
• C shape allows expansion of oesophagus
• ensure patency of the airway

Question 11

structure + function of bronchi ?

Answer 11

• trachea divides to from 2 bronchi
• similar to trachea = also have cartilage
• lined with ciliated epithelial cells = secrete mucus + saline
• trap + waft mucus to expel via coughing

Question 12

stages of saline secretion by airway epithelial cells

Answer 12

• NKCC transported (Na+, K+, 2Cl-) brings Cl- into epithelial cells from ECF
• apical anion channels eg. CFTR allow Cl- to enter lumen
• Na+ goes from ECF to lumen by the paracellular pathway, drawn by the electrochemical gradient
• NaCl movement from ECF to lumen creates concentration gradient
• so water flows into lumen

Question 13

structure of bronchioles

Answer 13

• no cartilage
• more smooth muscle
• muscarinic cholinergic receptors M3 causes bronchoconstriction
• B2 adreno-receptors cause bronchodilation

Question 14

what receptor causes bronchodilation ?

Answer 14

-B2 adreno-receptors

Question 15

what receptor causes bronchoconstriction ?

Answer 15

• M3

Question 16

structure of alveoli ?

Answer 16

• 2 types of epithelial cells
• type I = site for gas exchange
• type II = synthesize surfactant = reduces surface tension in alveolus thus reducing resistance when inhaling + exhaling

Question 17

what is essential for rapid gas exchange in alveoli ?

Answer 17

• proximity of alveolar air to capillary blood

Question 18

stages of pulmonary gas exchange + transport

Answer 18

• Oxygen (O2) from the air enters the alveoli.
• The blood in the alveolar capillaries is deoxygenated (full of CO2).
• O2 moves from the alveoli into the blood at the alveolar-capillary interface.
• CO2 moves from the blood into the alveoli.
• O2 diffuses into cells for cellular respiration.
• CO2 diffuses out of cells as a waste product.
• CO2 is enters alveolar at alveolar-capillary interface

Question 19

why is hemoglobin such as efficent oxygen carrier ?

Answer 19

• one haemoglobin molecule binds up to 4 oxygen molecules
• Hb binds to O2 only when iron is in the ferrous state
• complex causes blood to have red colour
• purple colour when devoid of O2

Question 20

what causes the oxygen-hemoglobin dissociation curve to shift to the right ?

Answer 20

• decreased pH
• decreased affinity
• increased PCO2
• increased temperature

Question 21

what causes the oxygen-hemoglobin dissociation curve to shift to the left ?

Answer 21

• increased pH
• increased affinity
• decreased PCO2
• decreased temperature

Question 22

carbon dioxide transport

Answer 22

• CO₂+H₂O —->H₂CO₃ ——> HCO₃⁻+H⁺
• catalysed by carbonic anhydrase
• dissociated into HCO3- ions
• transport to lungs
• HCO3- + H+ makes H₂CO₃
• carbonic anhydrase converts it to CO₂+H₂O
• CO2 diffuses from rbc to alveoil for exhalation

Question 23

what are the 3 principle respiratory muscles ?

Answer 23

• the diaphragm
• internal intercostal muscles
• external intercostal muscles

Question 24

what does the diaphragm separate?

Answer 24

• thorax from the abdomen

Question 25

what happens to respiratory muscles during inspiration ?

Answer 25

- diaphragm contracts - external intercostal muscles contracts - lift lungs upwards + outwards

Question 26

what happens to respiratory muscles during expiration ?

Answer 26

- diaphragm relaxes - internal intercostal muscles contracts - lift lungs inwards + downwards

Question 27

what is tidal volume ?

Answer 27

- volume of air that moves during single expiration or inspiration

Question 28

what is inspiratory reserve volume ?

Answer 28

- additional volume you inspire above the tidal volume - try and inspire as much as you can

Question 29

what is expiratory reserve volume?

Answer 29

- the amount of air forcefully exhaled after expiration

Question 30

what is the residual volume ?

Answer 30

- volume of air that cannot be expelled

Question 31

what is vital capacity ?

Answer 31

- sum of tidal volume + inspiratory + expiratory lung volume

Question 32

what is the total lung capacity?

Answer 32

- the sum of the vital capacity + residual volume

Question 33

what does peak flow measure ?

Answer 33

- how fast a patient can expire

Question 34

what % of HCO3- is in plasma ?

Answer 34

- 70%

Question 35

what % of CO2 is dissolved in blood ?

Answer 35

- 7%

Question 36

what % of circulating CO2 is bound to haemoglobin ?

Answer 36

- forms carbaminohaemoglobin - 23%

Question 37

what does forced vital capacity measure ?

Answer 37

- the volume of air which can be forcefully expelled after maximum inspiration