Lecture 16

Question 1

Alveoli

Answer 1

Sacs where gas exchange occurs, large surface area, one cell layer thick

Question 2

Type I alveolar cells

Answer 2

95 - 97 % total surface area of lung, very thin where gas exchange occurs

Question 3

Type II alveolar cells

Answer 3

Secrete surfactant and reabsorb sodium and water to prevent fluid build up

Question 4

Pressure during inspiration

Answer 4

Intrapulmonary pressure is lower than atmospheric pressure

Question 5

Pressure during expiration

Answer 5

Intrapulmonary pressure is greater than atmospheric pressure

Question 6

Boyle’s law

Answer 6

Pressure of a gas is inversely proportional to its volume
Thus an increase in lung volume decreases intrapulmonary pressure and air enters the lungs

Question 7

Surfactant function

Answer 7

Reduces surface tension between water molecules by reducing the number of hydrogen bonds between them, consists of hydrophobic proteins and phospholipids, becomes more concentrated as alveoli get smaller during expiration preventing collapse, also allows residual volume in lungs

Question 8

Tidal volume

Answer 8

Volume of air expired or inspired during quiet breathing

Question 9

Inspiratory reserve volume (irv)

Answer 9

Maximum amount of air that can be inspired after tidal volume

Question 10

Expiratory reserve volume

Answer 10

Maximum amount of air that can be forced out after tidal volume

Question 11

Residual volume

Answer 11

Amount of air left in lungs after maximum expiration

Question 12

Total lung capacity

Answer 12

Total amount of gas in the lungs after a maximum inspiration
Tidal volume + ERV + IRV + RV

Question 13

Vital capacity

Answer 13

Maximum amount of air that can be forcefully exhaled after a maximum inhalation
Tidal volume + ERV + IRV

Question 14

Inspiratory capacity

Answer 14

Maximum amount of gas that can be inspired after a normal expiration
Tidal volume + IRV

Question 15

Functional residual capacity (FRC)

Answer 15

Amount of gas left in the lungs after a normal expiration
ERV + RV

Question 16

Restrictive disorders

Answer 16

Vital capacity is reduced (damaged lung tissue) but forced expiration is normal
Emphysema, pulmonary fibrosis

Question 17

Obstructive disorders

Answer 17

Vital capacity is normal (no damage to lung tissue) but forced expiration rate is reduced
Asthma

Question 18

Partial pressure of gases in blood

Answer 18

O2 and CO2 in alveoli and blood capillaries quickly reach equilibrium due to high surface area and thin walls of alveoli plus the rich capillary network surrounding each alveolus

Question 19

Breathing 100% oxygen

Answer 19

Cannot significantly increase oxygen in red blood cells but does significantly increase amount of oxygen dissolved in blood plasma which increases the rate of oxygen diffusion to the tissues

Question 20

Pulmonary circulation

Answer 20

Pulmonary arterioles constrict when alveolar partial pressure O2 is low and dilate when high
Opposite reaction of systemic arterioles
Ensures ventilation (oxygen in lungs) matches perfusion (blood flow)

Question 21

Rhythmycity center

Answer 21

In medulla, generates respiratory rhythm via varying activity of inspiratory and expiratory neuron activity

Question 22

Pons/brainstem

Answer 22

Influences medulla activity, brainstem respiratory centers control breathing via axons to the phrenic motor nuclei in C3 -C6

Question 23

Chemoreceptors and breathing

Answer 23

Monitor pH of fluids in the brain plus pH, p CO2, and p O2 in the blood located in the medulla and carotid artery/aorta

Question 24

Peripheral chemoreceptors

Answer 24

In carotid bodies and aorta, sense H+, immediate response, control 20 - 30% ventilation

Question 25

Central chemoreceptors

Answer 25

In medulla, sense CO2, response is slow but responsible for 70 - 80% increased ventilation

Question 26

Oxyhemoglobin/deoxyhemoglobin

Answer 26

Iron is in reduced form and can bind oxygen

Question 27

Methemoglobin

Answer 27

Iron is oxidized and can't bind O2, abnormal, certain drugs can increase this

Question 28

Carboxyhemoglobin

Answer 28

Hemoglobin is bound with carbon monoxide which has 210 x stronger bond with co2 than O2

Question 29

Loading reaction

Answer 29

Deoxyhemoglobin binds to oxygen in the lungs

Question 30

Unloading reaction

Answer 30

Oxygen is dissociated from oxyhemoglobin in the tissues

Question 31

Favors loading

Answer 31

High PO2 in pulmonary capillaries

Question 32

Favors unloading

Answer 32

Low PO2 in systemic capillaries

Question 33

Oxygen reserve

Answer 33

Systemic veins have 75% oxyhemoglobin saturation with only 22% being unloaded in the tissues, the large amount of oxygen remaining can keep the heart and brain alive for 4-5 Ming

Question 34

Temperature effect on oxygen transport

Answer 34

Increased temperatures decreases hemoglobin's affinity for oxygen

Question 35

Bohr effect

Answer 35

Affinity for oxygen decreases at lower pH causing greater unloading, carbon dioxide transport enhances oxygen unloading

Question 36

Myoglobin

Answer 36

Red pigment in skeletal and cardiac muscles with 1 heme so it can only carry 1 oxygen, has high affinity for oxygen, oxygen storage in heart, transporter between blood and mitochondria

Question 37

Chloride shift

Answer 37

Exchange of bicarbonate out of cell and Cl- into the ABCs

Question 38

Reverse chloride shift

Answer 38

Occurs in pulmonary capillaries, increased PO2 favors oxyhemoglobin causing H+ to dissociate from hemoglobin and the H+ recombines with bicarbonate to form carbonic acid

Question 39

Metabolic acidosis

Answer 39

Person will hyperventilate blowing off CO2, H+ decreases, pH rises

Question 40

Metabolic alkalosis

Answer 40

Person will hypoventilate building up CO2, H+ increases, pH lowers