BMS 108 Ch. 16 Respiratory System

Question 0

What is ventilation?

Answer 0

Moves air in and out of lungs for gas exchange (external respiration)

Question 1

What three related functions does respiration encompass?

Answer 1

1. ventilation
2. gas exchange
3. O2 utilization

Question 2

What is gas exchange?

Answer 2

Exchange of gas between air and blood and blood and tissues.

Question 3

What is O2 utilization?

Answer 3

cellular respiration

Question 4

Is gas exchange active or passive?

Answer 4

passive; gas always exchanged down its concentration gradient

Question 5

How many alveoli in the lungs?

Answer 5

300 million

Question 6

What is an alveolar type 1 cell? type 2?

Answer 6

alveolar wall; cell that secretes surfactant in the alveoli

Question 7

What law governs ventilation?

Answer 7

Boyle’s Law (P=1/V)

Question 8

What is compliance?

Answer 8

• how easy the lungs expand with pressure

- reduced by factors that cause resistance to distention (e.g. pulmonary fibrosis)

Question 9

What is elasticity?

Answer 9

• the tendency to return to initial size after distention

- elastic tension increases during inspiration and is reduced by recoil during expiration

Question 10

What is surface tension?

Answer 10

• cohesive forces between liquid molecules that allows them to resist an external force

Question 11

What causes surface tension in water molecules?

Answer 11

Hydrogen bonds

Question 12

What are the forces that promote alveolar collapse and resist distention?

Answer 12

surface tension and elasticity

Question 13

Surface tension acts to ________ the alveoli; thus __________ pressure of air within alveoli.

Answer 13

collapse; increases

Question 14

Why don’t alveoli normally collapse?

Answer 14

surfactant

Question 15

What is surfactant secreted by? What is it’s function?

Answer 15

Type II alveolar cells; lowers surface tension by getting between H20 molecules, preventing surface tension from collapsing alveoli

Question 16

What connects the lungs to the thoracic cavity?

Answer 16

the pleura

Question 17

What is intrapulmonary pressure?

Answer 17

• pressure inside alveoli (inside lungs)
• must become < atmospheric P for air to enter lungs
• when intrapulmonary P is > than atmospheric P, expiration occurs

Question 18

What is intrapleural pressure?

Answer 18

• pressure in the intrapleural space (outside the lungs)

- due to thoracic cavity pulling out and the lungs trying to collapse in (elasticity & surface tension)

Question 19

What is partial pressure of gases?

Answer 19

The pressure that a particular gas in a mixture exerts independently.

Question 20

What is Dalton’s Law?

Answer 20

States that total pressure of a gas mixture is the sum of partial pressure of each gas in a mixture.

Question 21

What is atmospheric pressure at sea level?

Answer 21

760 mm Hg

Question 22

What is gas exchange in the lungs driven by?

Answer 22

Difference in partial pressures of gases between alveoli and capillaries.

Question 23

What three things facillitate diffusion of gases in the alveoli?

Answer 23

1. enormous surface area of alveoli
2. short diffusion distance between alveolar air and capillaries
3. tremendous density of capillaries

Question 24

What are the normal arterial partial pressures of O2 and CO2? veins?

Answer 24

100mmHg, 40mmHg; 40mmHg, 46mmHg

Question 25

What is breathing regulated by?

Answer 25

- autonomic breathing is generated by a rhythmicity center in the medulla oblongata

Question 26

How does the medulla know what rate and depth to breathe at?

Answer 26

Using chemoreceptors in the aortic arch, carotid sinus and medulla

Question 27

What are these chemoreceptors triggered by?

Answer 27

a rise in H+

Question 28

What is hypocapnia?

Answer 28

low CO2, caused by hyperventilation

Question 29

What is hypercapnia?

Answer 29

high CO2; caused by hypoventilation

Question 30

What is respiratory acidosis?

Answer 30

a rise in carbonic acid in the blood caused by hypoventilation

Question 31

What is respiratory alkalosis?

Answer 31

hyperventilation that results in low blood CO2

Question 32

Which chemoreceptors have the greatest effect on ventilation?

Answer 32

medulla

Question 33

Can H+ cross the BBB? CO2?

Answer 33

No; yes

Question 34

What is the arterial pCO2 level the body tries to maintain?

Answer 34

40mmHg

Question 35

How sensitive are chemoreceptors to H+? pCO2? pO2?

Answer 35

Most sensitive; less sensitive; barely notice

Question 36

What is hypoxemia? what effect does it have on ventilation?

Answer 36

low blood pO2; little

Question 37

Is the bulk of O2 in the blood dissolved O2 or bound to hemoglobin?

Answer 37

bound to hemoglobin

Question 38

How many O2 molecules can each hemoglobin carry? How many hemoglobins in 1 RBC? how many RBCs in the body?

Answer 38

4; 300 mil; 300 mil

Question 39

What is hemoglobin bound with O2 called? unbound?

Answer 39

oxyhemoglobin; deoxyhemoglobin

Question 40

High pO2 in lungs (alveoi) favors _________; low pO2 in tissues favor __________.

Answer 40

loading; unloading

Question 41

Arterial hemoglobin is ___% saturated with O2.

Answer 41

97

Question 42

What causes changes in Hb-O2 affinity?

Answer 42

pH and temperature

Question 43

Affinity ____ when pH decreases (Bohr effect) or temperature increases.

Answer 43

decreases

Question 44

Decrease affinty = _________ unloading.

Answer 44

better

Question 45

How is CO2 transported in the blood?

Answer 45

1. dissolved CO2 (10%) 2. carbaminohemoglobin - bound to hemoglobin (20%) 3. bicarbonate ion - HCO3- (70%)

Question 46

How is H2CO3 catalyzed into CO2 and H2O?

Answer 46

With carbonic anhydrase (enzyme)

Question 47

What is the chloride shift?

Answer 47

1. High CO2 levels in blood cause bicarbonate buffer equation to shift right 2. Results in high H+ and HCO3- in RBC 3. HCO3- in RBC diffuss down concentration and charge gradient into blood plasma 4. Counteracted by Cl- moving into the RBC

Question 48

Where does the chloride shift occur?

Answer 48

in tissues

Question 49

What is the reverse chloride shift?

Answer 49

1. In lungs, bicarbonate buffer equation shifts left as CO2 is exhaled 2. Binding of O2 to hemoglobin decreases its affinity for H+ 3. H+ combines with HCO3- and more CO2 is formed 4. Cl- diffuses down concentration gradient out of RBC

Question 50

What is the normal pH of the blood?

Answer 50

7.4

Question 51

What is the kidney's role in acid-base blood balance?

Answer 51

excrete H+