npb101 respiratory system

what factor is the main driving force of ventilation at rest?

excess of co2

t/f: in general, respiration obtains o2 for use by body's cells

t

t/f: in general, respiration eliminates co2 produced by body's cells

t

name 2 passages where external air can enter through

nasal passages and mouth

tube lined by cartilaginous ring, branches into left and right bronchi

trachea

which alveolar cell type forms a flattened single layer that makes up the alveoli wall?

type 1

which alveolar cell type secretes pulmonary surfactant?

type 2

alveolar macrophage function

guard lumen, serves as immune filter in alveoli

each alveoli is surrounded all over by

pulmonary capillaries

trachea/larger bronchi vs. bronchioles (in terms of cartilage)

trachea/larger bronchi have rings of cartilage that prevent collapse.
bronchioles have no cartilage to hold them open -> more vulnerable to collapse

effect of parasympathetic stimulation on bronchioles

constrict to avoid unnecessary influx of air

effect of sympathetic stimulation on bronchioles

weakly relaxes to facilitate gas exchange. vasoconstriction also happens

pulmonary surfactant functions

- disrupts H bonding of water lining alveolar wall
- decreases surface tension so that little bubbles don't collapse on a small number of bigger ones

are healthy infants born with pulmonary surfactant? if yes, what induces it?

yes, cortisol

double-walled, closed sac, separates each lung from thoracic wall

pleural sac

why doesn't the pleural sac expand/collapse?

the pleural sac is filled with water

is water a compressible medium?

no

interior of pleural sac

pleural cavity

lubricant secreted by surfaces of pleura

interpleural fluid

why is breathing usually effortless?

lungs constantly tug on thorax, but there is not much friction. low energy process

what 3 pressures are important in ventilation?

atmosphere (barometric), intra-alveolar/intrapulmonary, intrapleural/intrathoracic pressures

intrapleural pressure is ALWAYS (greater/lower) than intra-alveolar pressure

lower

what is the mean arterial pressure in the lungs?

760 mmHg (+93)

what are the 2 main muscles in inspiration?

diaphragm (normal breathing) and external intercostal muscles (deep breathing)

the thorax gets (smaller/larger) during inspiration

larger

inspiration is a/an (active/passive) process

active

inspiration causes a slight ____pressure in lungs

under

the thorax gets (smaller/larger) during expiration

smaller

what are the 2 main muscles in expiration?

abdominal muscles and internal intercostal muscles

expiration at rest is an (active/passive) process, but we can engage the abdominal/internal intercostals for maximum exhalation

passive

expiration causes a slight ____pressure in lungs

over

compare intra-alveolar P with atmospheric P during inspiration

intra-alveolar P < atmospheric P

compare intra-alveolar P with atmospheric P during expiration

intra-alveolar P > atmospheric P

compare intra-alveolar P with atmospheric P at the end of inspiration/expiration

they are equal

transmural pressure gradient

difference between intrapleural and intra-alveolar pressure, always exists

t/f: lungs are always stretched to some degree, even during exipration

t

what happens if you damage/poke the intrapleural space?

intrapleural P > intra-alveolar P, lungs would deflate/collapse

do we usually use the lung's full capacity?

no, not necessary during rest

t/f: gas exchange happens all the time because there's always some amount of air in the alveoli

t

amount of air that moves in/out of lungs per breath

tidal volume (500 mL)

maximum amount of air in lungs during inspiration

inspiratory reserve volume (IRV), 3000 mL

inspiratory capacity

3500 mL

maximum amount of air during expiration

expiratory reserve volume (ERV), 1000 mL

minimal lung volume

residual volume, 1200 mL

amount of air that doesn't take part in gas exchange because it's "taken up" by anatomy (i.e. tubing)

anatomical dead space

how do you calculate pulmonary ventilation?

tidal volume x respiratory rate

how do you calculate alveolar ventilation?

(tidal volume - dead space) x respiratory rate

average breaths/min at rest

12 breaths/min

name the 4 factors that influence the rate of gas transfer across the alveolar-capillary membrane. which one is the major determinant?

- partial pressure gradients of o2 and co2 (major determinant)
- surface area of alveolar-capillary membrane
- thickness of alveolar-capillary membrane
- diffusion constant

how does alveolar air composition differ from atmospheric air? (3 factors)

alveolar air composition has:
- increased water vapor as air travels down airways
- anatomical dead space
- residual volume

thin air/higher altitudes (increase/decrease) partial pressure

decrease

how is most oxygen transported?

via hemoglobin

1 Hb can bind ___ O2

4

how is most co2 transported?

as bicarbonate (HCO3-)

what is the main factor determining % Hb saturation?

oxygen partial pressure

% saturation of Hb is high when oxygen partial pressure is (high/low)

high

where in the body is oxygen partial pressure high?

lungs

where in the body is oxygen partial pressure low?

tissue cells

in the oxygen Hb dissociation curve, the plateau represents

where the partial pressure of o2 is high

in the oxygen Hb dissociation curve, the steep part represents

where Hb unloads oxygen to the tissue cells

describe the Bohr effect

increased co2 and h+ at tissues right-shifts the o2 dissociation curve

since dissolved co2 can't bind to Hb right away, what can it do? (2 methods)

- diffuse into RBC
- react with water to form hco3- and h+

what facilitates the reaction of water and co2 to form bicarbonate?

carbonic anhydrase

why does sickle cell affect gas exchange?

- gets stuck in vessels -> decrease blood flow
- rigid, breaks down more easily -> can't efficiently maintain hematocrit
- doesn't bind o2 that well -> affects gas exchange

underventilation in relation to metabolic requirements

hypoventilation

how does hypoventilation affect co2 partial pressure and h+ concentration?

both increase

hypoventilation leads to respiratory ______

acidosis

increased pulmonary ventilation in excess of metabolic requirements

hyperventilation

how does hyperventilation affect co2 partial pressure and h+ concentration?

both decrease

hyperventilation leads to respiratory _____

alkalosis

what do respiratory centers do?

control rhythmic firing of motor neurons

name the 2 medullary respiratory centers and their functions

dorsal respiratory group: inspiratory, active in normal/quiet breathing
ventral respiratory group: inspiratory and expiratory, activated upon demand

function of pons respiratory centers

modulate activity of medullary centers, promote smooth breathing rhythms

function of pre-botzinger complex

generates respiratory rhythm

function of hiring Breuer reflex

stretch receptors that inhibit medullary center to prevent over-inflation of lungs

these chemoreceptors are only activated during emergency situations and are activated by a decrease in o2/increase in h+

peripheral

these chemoreceptors are in the medulla. they send excitatory input to inspiratory neurons and are activated by an increase in co2 partial pressure in arterial blood (+ increase in h+ in brain ECF)

central