ch 22 quiz review

Question 1

alveolus

alveolus

Answer 1

is a pouch about 0.2 to 0.5 mm in diameter

Question 2

alveolus

squamous type 1 alveolar cells

Answer 2

thin, broad cells
cover about 95%

Question 3

alveolus

type II alveolar cells

Answer 3

round, cuboidal cells
covers 5%

Question 4

alveolus

dust cells

Answer 4

macrophages that eat bacteria
most numerous of all cells in the lung
wander the lumens of the alveoli and the connective tissue between them

Question 5

alveolus

each alveolus is surrounded by a

Answer 5

web of blood capillaries supplied by small branches of the pulmonary artery

Question 6

alveolus

respiratory membrane

Answer 6

the barrier between the alveolar air and blood
consists of
* squamous alveolar cells,
* the squamous endothelial cell of the capillary
* and their shared basement membrane

Question 7

henry’s law

henry’s law

Answer 7

states that at the air-water interface, for a given temp, the amount of gas that dissolves in the water is determine by its solubility in water and its partial pressure in the air

Question 8

henry’s law

thus the greater the

Answer 8

• PO2PO2 in the alveolar air, the more O2O2 the blood picks up.
• And since blood arriving at an alveolus has a higher Pco2Pco2 than air, it releases CO2CO2 into the air.
• At the alveolus, the blood is said to unload CO2CO2 and load O2O2.
• Each gas in a mixture behaves independently; the diffusion of one gas does not influence the diffusion of another.

Question 9

hemoglobin

hemoglobin does not unload the same amount of

Answer 9

oxygen to all tissues

Question 10

hemoglobin

some tissues need more and some less depending on their

Answer 10

state of activity

Question 11

hemoglobin

hemoglobin responds to such variations and unloads

Answer 11

more oxygen to the tissues that need it most

Question 12

hemoglobin

when temp rises the oxyhemoglobin dissociation curve shifts to the

Answer 12

right
* in other words elevated temp promotes oxygen unloading

Question 13

hemoglobin

active tissues are wamer than

Answer 13

less active ones and thus extract more oxygen from the blood passing through them

Question 14

hemoglobin

active tissues also generate extra

Answer 14

CO2 which raises the H+ concentration and lowers the pH of the blood

Question 15

hemoglobin

hydrogen ions weaken the bond between

Answer 15

hemoglobin and oxygen and thereby promote oxygen unloading
* a phenomenon called the Bohr effect

this can be seen in the oxyhemoglobin dissociation curve where a drop in pH shifts the curve to the right

Question 16

air that actually enters the alveoli becomes available for

Answer 16

gas exchange
* but not all inhaled air gets that far

Question 17

anatomical dead space

Answer 17

• about 150 mL of it fills the conducting zone of the airway
• since this air cannot exchange gases with the blood
• typically about 1 mL per pound of bodyw weight in a healthy person

Question 18

Systemic gas exchange

Systemic gas exchange

Answer 18

is the unloading of O2 and loading of CO2 at the systemic capillaries.

Question 19

Systemic gas exchange

Oxygen Unloading

Answer 19

• When H+ binds to oxyhemoglobin (HbO2), it reduces the affinity of hemoglobin for O2 and tends to make hemoglobin release it.
• Oxygen consumption by respiring tissues keeps the PO2 of tissue fluid relatively low, thus the liberated oxygen diffuses from the blood into the tissue fluid.

Question 20

Systemic gas exchange

Carbon Dioxide Loading

Answer 20

• Aerobic respiration produces a molecule of CO2 for every molecule of O2 it consumes.
• The tissue fluid contains a relatively high Pco2, thus CO2 diffuses into the bloodstream.
• Most of it reacts with water to produce bicarbonate and hydrogen ions

Question 21

Systemic gas exchange

chloride shift

Answer 21

An antiport called the chloride-bicarbonate exchanger then pumps most of the HCO3− out of the RBC in exchange for Cl– from the blood plasma.

Question 22

the automatic unconscious cycle of breathing is controlled by

Answer 22

3 pairs of respiratory centers in the reticular formation of the medulla oblongata and pons

Question 23

ventral respiratory group (VRG)

Answer 23

the primary generator of the respiratory rhythm

Question 24

dorsal respiratory group (DRG)

Answer 24

an integrating center that receives input from several sources
* respiratory center in the pons
* a chemosensitive center of the anterior medulla oblongata
* chemoreceptors in certain major ateries
* and stretch and irritant receptors in the airway

Question 25

the DRG issues output to the

Answer 25

VRG that modifies the respiratory rhythm to adapt to varying conditions

Question 26

furthermore each side of the pons has a

Answer 26

pontine respiratory group (PRG) that modifies the rhythm of the VRG

Question 27

the pontine group receives input from higher brain centers including the

Answer 27

• hypothalamus
• limbic system
• cerebral cortex
• and issues output to both DRG & VRG

Question 28

multiple sensory receptors also provide info to the

Answer 28

respiratory centers

Question 29

central chemoreceptors

Answer 29

brainstem neurons that respond especially to changes in the pH of the cerebrospinal fluid

Question 30

peripheral chemoreceptors

Answer 30

• located in the carotid and aortic bodies of the large arteries above the heart
• they respond to the O2 and CO2 content of the blood but most of all to ph

Question 31

normally the systemic arterial blood has a

Answer 31

PO2 of 95 mm Hg
PCO2 of 40 mm Hg
pH of 7.40

Question 32

systemic arterial blood

the rate and depth of breathing are adjusted to

Answer 32

maintain these values

Question 33

systemic arterial blood

this is possible only because the

Answer 33

brainstem respiratory centers receive input from central and peripheral chemoreceptors that monitor the composition of the blood and CSF

Question 34

systemic arterial blood

of these 3 chemical stimuli the most potent

Answer 34

stimulus for breathing is pH, followed by CO2; perhaps suprisingly the least significant is O2

Question 35

systemic arterial blood

PO2:
PCO2

Answer 35

PO2: partial pressure of oxygen
PCO2: partial pressure of carbon dioxide

Question 36

size of cell changes

the inner lining of the trachea is a

Answer 36

pseduostratified columnar epithelium composed mainly of mucus-secreting goblet cells, ciliated cells, and short basal stem cells

Question 37

size of cell changes

the mucus traps inhaled particles and the upward

Answer 37

beating of the cilia drives the debris-laden mucus toward the pharynx where is it swallowed

this mechanism of debris removal is called the mucociliary escalator

Question 38

size of cell changes

all of the bronchi are lined with

Answer 38

pseduostratified columnar epithelium but the cells grow shorter and the epithlium thinner as we progress distally

Question 39

bronchioles

bronchioles have a

Answer 39

ciliated epithelium and a well-developed layer of smooth muscle in their walls

Question 40

bronchioles

the terminal bronchioles have no

Answer 40

mucous glands or goblet cells

Question 41

bronchioles

they do have cilia however

Answer 41

so that mucus draining into them from above can be driven back by the mucociliary escalator preventing congestion of the terminal bronchioles and alveoli

Question 42

bronchioles

each respiratory bronchiole divides into

Answer 42

alveolar ducts which also have alveoli along their walls

Question 43

bronchioles

the alveolar ducts and smaller divisions have

Answer 43

nonciliated simple squamous epithelia