Oxygenation

Question 1

what does the upper respiratory system consist of?

Answer 1

nose, pharynx and associated structures

Question 2

what does the lower respiratory system consist of?

Answer 2

larynx, trachea, bronchi and lungs

Question 3

what is the larynx?

Answer 3

voice box.

passageway that connects pharynx and trachea

Question 4

where is the trachea?

Answer 4

larynx to primary bronchi

Question 5

what is cartilage?

Answer 5

flexible tissue. keeps airway open and stops them collapsing

Question 6

where is the bronchi?

Answer 6

trachea branches into left and right primary bronchus, and each enter left and right lung
- upon entering lungs, primary bronchi further divide into smaller branches (bronchioles)

Question 7

what is the conducting zone?

Answer 7

nose, pharynx, larynx, trachea, bronchi, bronchioles

- they filter, warm and moisten air and conduct it into respiratory zone

Question 8

what is the respiratory zone?

Answer 8

bronchioles and alveolar ducts (10% gas exchange)

alveoli (90% gas exchange)

Question 9

what is dead space?

Answer 9

the conducting zone represents dead space.

amount of air inhaled which does not participate in gas exchange (approx. 2.2mL per kg of body weight)

Question 10

what is alveoli?

Answer 10

air sacs found within lungs
two types:
1. gas exchange
2. produce surfactant

Question 11

explain blood supply to the lungs.

Answer 11

enters the lungs via the pulmonary arteries (pulmonary circulation) and the bronchial arteries (systemic circulation)
exits the lungs via pulmonary veins and bronchial veins

Question 12

explain the importance of smooth muscle.

Answer 12

smooth muscle in smaller airways enables control of the diameter of the airways in relation to the rate of gas exchange required

Question 13

what is the role of pleurae?

Answer 13

• lines thoracic wall and diaphragm and onto the lung
• reduces friction during breathing
• helps create negative pressure (breathe in) and a more positive pressure (breathe out)

Question 14

identify the factors affecting pulmonary ventilation.

Answer 14

• surface tension: inwardly directed force in alveoli which must be overcome to expand lungs during each inspiration
• elastic recoil: decreases size of alveoli during expiration
• compliance: ease with which lungs and thoracic wall can be expanded

Question 15

what is external and internal respiration?

Answer 15

external: oxygen diffuses from alveoli into pulmonary capillaries
internal: oxygen diffuses from systemic capillaries into tissue

Question 16

what is the oxygen-haemoglobin dissociation curve?

Answer 16

most oxygen is carried attached to haemoglobin (97-98%)

describes relation between partial pressure of oxygen and oxygen saturation

• normal range =
• PaO2 80-100mmHg
• SaO2 95-99%

Question 17

what is cyanosis?

Answer 17

bluish discolouration of skin and mucous membrane due to increased amounts of desaturated Hb/reduced Hb

Question 18

why does ventilation rate change?

Answer 18

changes due to changes in oxygen demand and/or carbon dioxide levels in the blood

• predominantly controlled by carbon dioxide
• chemoreceptor in brain stem, carotid arteries and aortic arch detect elevated carbon dioxide in blood and stimulate respiratory centre in medulla oblongata

Question 19

what is cortical influence of respiration?

Answer 19

conscious control of respiratory rate that may be needed

Question 20

what is hypoxia?

Answer 20

oxygen deficiency at tissue level, caused by low Po2 in arterial blood due to high altitude, airway obstruction or fluid in the lungs

Question 21

what factors affect the drive to breathe?

Answer 21

• blood levels of carbon dioxide
• narcotics
• brain damage
• elevated ICP
• decrease in metabolic rates