L9.1 Respiratory System I

Question 1

what are the functions of the respiratory system?

Answer 1

• gas exchange between atmosphere and blood
• speech (vocal cords)
• smell (nasal passage)
• maintains pH of blood
• enhances venous return

Question 2

what are the steps of external respiration

Answer 2

1. ventilation or gas exchange between the atmosphere and air sacs (alveoli) in the lungs
2. exchange of O2 and CO2 between air in the alveoli and the blood in the pulmonary capillaries
3. transport of O2 and CO2 by the blood between the lungs and the tissues
4. exchange of O2 and CO2 between the blood in the systemic capillaries and the tissue cells

Question 3

what is the process of breathing called?

Answer 3

ventilation

Question 4

what is cellular respiration?

Answer 4

taking food and oxygen to produce ATP, carbon dioxide and water
(food + O2 -> CO2 + H2O + ATP)

Question 5

what is the anatomy of the respiratory system?

Answer 5

nasal cavity (or oral) -> pharynx + larynx -> trachea -> bronchi -> bronchioles -> alveoli

Question 6

what are the cells of the alveoli?

Answer 6

type I alveolar cell: squamous cells lining the alveoli
type II alveolar cell: produce surfactant
alveolar macrophages: phagocytose foreign material

Question 7

what is the respiratory membrane?

Answer 7

boundary between the air and the blood: type I alveolar cell + endothelial cell + basement membranes

Question 8

what is gas exchange optimised by?

Answer 8

factors affecting diffusion rate: short diffusion distance and large surface area

Question 9

what are the branches of the bronchial tree?

Answer 9

trachea -> bronchi -> bronchioles -> terminal bronchioles -> respiratory bronchioles

Question 10

what is the function of the cartilage in the trachea and bronchi?

Answer 10

structural support = keeps airway open

Question 11

what is the function of the smooth muscle in bronchioles?

Answer 11

allow small airways to dilate or constrict (bronchodilation, bronchoconstriction)

Question 12

describe the features of the pleural sac

Answer 12

• double walled closed sac
• between lungs and thoracic wall (layer over the surface of the lung and then layer around the wall of the thoracic cavity)
• filled with intrapleural fluid (lubricates pleural surfaces, ‘sticks’ lungs to thoracic wall = surface tension)
• each lung is surrounded by the pleura and inside the pleura is completely seperated from the lungs

Question 13

describe atmospheric pressure

Answer 13

• pressure exerted by weight of air on objects on earth’s surface
• decreases with height from sea level
• sea level = 760 mm Hg

Question 14

describe intra-alveolar pressure

Answer 14

the pressure within the alveoli (760 mm Hg when equilibrated with atmospheric pressure)

Question 15

describe intrapleural pressure

Answer 15

the pressure within the pleural sac- the pressure exerted outside the lungs within the thoracic cavity, usually less than atmospheric pressure at 756 mm Hg

Question 16

during development, the thoracic wall grows more quickly than the lungs- the chest wall and lungs want to pull apart. The thoracic wall and lungs are held together by two forces …….

Answer 16

• surface tension from intrapleural fluid

- transmural pressure gradient

Question 17

what is the transmural pressure gradient?

Answer 17

the pressure difference between the lungs and pleural cavity. pushes lungs out towards the thoracic cavity

Question 18

describe Boyle’s Law

Answer 18

relationship between volume and pressure
- pressure of a gas in a container varies inversely with the volume of the gas e.g. increasing the volume decreases the pressure
P1V1 = P2V2

Question 19

describe the process of inspiration

Answer 19

contraction of diaphragm and external intercostal muscles -> lung volume increases -> slight drop in intra-alveolar pressure -> air enter lungs

Question 20

inspiration is muscle activity working ____ elastic recoil

Answer 20

inspiration is muscle activity working AGAINST elastic recoil

Question 21

describe the process of expiration

Answer 21

diaphragm and external intercostals relax-> lung volume decreases -> slight rise in intra-alveolar pressure -> air leaves lungs
(expiration is a passive process- no contraction of muscles)

Question 22

describe forced breathing- inspiration

Answer 22

• further contraction of external intercostals and diaphragm (as much as 10cm)
• contraction of accessory muscles in neck

Question 23

describe forced breathing- expiration

Answer 23

• internal intercostals draw in ribs
• abdominal muscles contract and push diaphragm
• forced expiration is not passive

Question 24

forced expiration is muscle activity working _____ elastic recoil

Answer 24

forced expiration is muscle activity working WITH elastic recoil