Respiratory system

Question 1

functions of respiratory system

Answer 1

• provides oxygen and eliminate carbon dioxide
• regulates blood H+ level in coordination with kidneys
• forms speech sounds
• defends against microbes
• influences arterial contractions of chemical messengers by removing some from pulmonary capillary blood and producing others to this blood
• traps and dissolves blood clots arising from systemic veins

Question 2

what is compliance and elastance?

Answer 2

compliance: refers to effort required to distend lungs

elastance: tendency to recoil after distension
- facilitates alveoli interdependence: when one alveolus starts to collapse, neighbouring alveoli recoil to pull and expand collapsing alveoli

Question 3

what is pulmonary surfactant

Answer 3

complex phospholipid proteins secreted by type II alveolar cells to reduce surface tension to increase compliance and prevent smaller alveoli from collapsing

Question 4

what is newborn respiratory distress syndrome?

Answer 4

due to lack of pulmonary surfactant, occurs mostly in premature infants

characterised by deficiency in pulmonary surfactant > increase surface tension > low compliance

treatment: synthetic/natural surfactant through breathing tube; glucocorticoids stimulate production of pulmonary surfactant

Question 5

function of cortisol on lungs

Answer 5

promotes surfactant secretion

Question 6

what is pneumothorax?

Answer 6

occurs due to loss of transmural pressure gradient > lungs collapse

Question 7

how does ventilation occur

Answer 7

increase in lung volume decreases pulmonary pressure > air in

decrease in lung volume increases pulmonary pressure > air out

Question 8

what happens during inspiration?

Answer 8

at rest:
- contraction of diaphragm raises thoracic volume vertically (downwards)
- contraction of external intercostals expands cage up and out

forceful:
- accessory inspiratory muscles raise the sternum and first 2 ribs to expand upper thorax

Question 9

what happens during expiration?

Answer 9

passive:
- after being stretched, external intercostal muscles and diaphragm relax > lungs recoil

active:
- internal intercostal muscle contract to reduce front-to-back dimensions of thoracic cavity
- abdominal muscles contract to push diaphragm upward, reducing vertical dimension

Question 10

what happens during Epi + sympathetic stimulation?

Answer 10

bronchodilation and reduced secretion via beta 2 adrenergic receptors > reduce air coming into lungs by relaxing lung muscles

Question 11

what happens during parasympathetic stimulation

Answer 11

bronchoconstriction and increase of secretion via muscarinic receptor

Question 12

what are the local factors for bronchodilation and bronchoconstriction?

Answer 12

increased CO2 > bronchodilation

histamine and cold air > bronchoconstriction

Question 13

what are the pulmonary disorders?

Answer 13

obstructive:
- asthma: airway blocked by inflammation, mucus secretion and spasm of smooth muscles
- chronic bronchitis: similar but of less extent than asthma
- emphysema: alveolar tissue destroyed by tryposin

restrictive:
- pulmonary fibrosis: lung tissue disrupted by accumulation of fibrous connective tissue
- asbestosis: inflammatory and fibrotic lung condition caused by inhalation of asbestos > hard to expand lungs

Question 14

what happens during abnormal blood oxygen and carbon dioxide levels?

Answer 14

hypoxia: insufficient O2 at cellular levels

hypoxic hypoxia: hypoxia due to insufficient O2 available to lungs

hyperpoxia: above normal arterial Po2

hypocapnia: below normal arterial Pco2 due to hyperventilation

hypercapnia: excess CO2 in arterial blood due to hypoventilation

apnea: cessation of breathing

pyspnea: shortness of breath