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NPB 101 > RESPIRATORY SYSTEM > Flashcards

RESPIRATORY SYSTEM Flashcards

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1
Q

respiration

A

obtain O2 for body cells & eliminate CO2
* build up of CO2 = toxic ➔ lowers pH
* veins (blue) still have O2 but much less
* arteries (red) still have CO2 but much less

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2
Q

types of respiration

A

external respiration
* pulmonary circulation: heart & lungs
* systemic circulation: throughout rest of body

internal (cellular) circulation

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3
Q

respiratory system composed of

A
  • nasal passage
  • mouth
  • pharynx
  • larynx trachea (w/ cartilaginous tissue for strength)
  • lungs
  • diaphragm

always leads to lungs

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4
Q

airways

A

trachea & larger bronchi: fairly rigid rings of cartilage to prevent collapse

bronchioles:
* no cartilage to hold them open ➔ makes them susceptible to collapse
* walls contain smooth muscles innervated by ANS
* parasympathetic stimulation constricts
* just sympathetic stimulation weakly relaxes
* EP relaxes

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5
Q

alveoli anatomy

A

alveoli: site of O2/CO2 exchange
* thin-walled flexible sacs

type 1 alveolar cell: large cavity that allows gas exchange
* single layer makes up alveoli walls

type II alveolar cell: produces alveoli fluid lining with pulmonary surfactants:
* weak detergent
* ↓ surface area to prevent collapse
* normalizes pressure
* prevents recoil
* disrupts H-bonding of water lining alveolar wall (mixture of protein & lipid) to prevent large bubble formation from smaller ones

alveolar macrophage protects alveolus & ensures clean air
* guard lumen

pulmonary capillary brings O2/CO2
* encircle each alveolus
* erythrocyte = RBC
* barrier separating alveoli & capillary = extremely thin & short distance to facilitate gas exchange by diffusion

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6
Q

pulmonary ventilation

A

lungs suspend in pleural sac in thorax
* pleural sac = extremely thin double-walled closed sac separating each lung from thoracic wall
* pleural cavity = interior of pleural sac
* intrapleural fluid = lubricant secreted by surfaces of pleura
* helps lung with movement & prevents friction
* helps with pressure regulation

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7
Q

ventilation pressure

A
  1. atmospheric (barometric) pressure: exerted by weight of gas in atm on objects in earth’s surface
  2. intra-alveolar (intrapulmonary) pressure: w/in alveoli
    • changes produce flow of air in/out of lungs by diffusion
      • if < Patm ➔ air enters lungs
      • if > Patm ➔ air exits lungs
      • boyles law: P & V are inversely related ➔ ↑P = ↓V
  3. intrapleural (intrathoracic) pressure: w/in pleural sac
    • pressure exerted outside the lungs within the thoracic cavity
    • Pintrapleural < P intra-alveolar
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8
Q

inspiration

A

inhaling
* external intercostal muscles & diaphragm only
* both intra-alveolar & intrapleural pressures drop 1 mmHg ➔ allows for more inflation
* contraction of EIM causes
1. ribs & sternum elevate ➞ ↑ side-to-side & up & out
2. diaphragm lowers ➞ ↑ vertical dimension

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9
Q

expiration

A

passive expiration during quiet breathing
* diaphragm, ribs, & sternum return to resting position
* inspiratory muscles relax
* restore TC to pre-inspiratory size
* via elastic recoil
* relaxation of diaphragm & intercostals muscles

active expiration ↓ dimensions of TC even more than resting state:
1. contraction of internal intercostals flattens ribs & sternum ➔ ↓ side-to-side & front-to-back dimensions
2. contraction of abdominal muscles pushes diaphragm up ➔ ↓ vertical dimension

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10
Q

intrapulmonary (intra-alveolar) & intrapleural pressures during respiratory cycle

A
  1. inspiration: P intra-alveolar < P atm
  2. expiration: P intra-alveolar > P atm
  3. at and of both: P intra-alveolar = P atm
  4. throughout: P intrapleural < P intra-alveolar
  5. ∴ transmural pressure gradient always exists ➔ lung is always stretched a bit even during expiration
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11
Q

lung volumes

A

TV = tidal volume: small amount we actually take in during inspiration/expiration

IRV = inspiratory reserve volume: V of air we can use during strenuous situations

  • FOF
  • exercise

IC = inspiratory capacity: max V we can inspire

ERV = expiratory reserve V ➔ forced expiration after normal expiration

RV = residual V ➔ volume that will be left over after we expire completely

FRC = functional residual capacity ➔ RV + ERV ➔ not actual amount we can use

VC = vital capacity ➔ TLC - minimum amount of air necessary for normal fx; amount of air we can regulate

TLC = total lung capacity

  • dead space = non-fresh air; cannot be used by alveoli ➔ does not provide O2
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12
Q

ventilation

A

pulmonary ventilation (mL/min) = TV (mL/min) x RR (breaths/min)

  • not all TV can be used by alveoli & contribute to ventilation ➔ only fresh air
  • only ~70% of inspiration = fresh air ∴ only ~350mL fresh air reaches alveoli

alveolar ventilation (L/min) = (TV — dead space) x RR

  • alveolar ventilation < total ventilation
  • during hyperventilation alveolar ventilation = ~0 ➔ very little fresh air reaches alveoli, just reusing dead air

feedback mechanisms within lung match local airflow w/ local blood flow

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13
Q

gas exchange

A
  • simple diffusion between pulmonary capillary & alveoli in extremely close proximity
  • major determinant of rate of transfer = PP gradients of O2 & CO2
  • SA of alveolar capillary membrane: ROT↑ as SA↑
    • constant at resting conditions
    • ↑ during exercise
    • ↓ w/ pathologies
  • thickness of alveolar-capillary membrane: ROT ↑ as thickness ↓
    • normally remains constant
    • ↑ w/ pathologies (pulmonary edema, pulmonary fibrosis, pneumonia)
  • diffusion constant: ROT ↑ as diffusion constant ↑
    • diffusion constant CO2 = 20x O2
    • balances w/ smaller particle pressure gradient of CO2
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14
Q

alveolar air composition

A
  • diff than atm: atm ➔ alveoli:
    • %N ↓ ➔ same amount just diff ratio
    • %O2 ↓
      a. diffusing out for cellular resp
      b. not all air = fresh air
    • % CO2 ↑
      a. byproduct of cellular resp
      b. deadspace
    • % H2O ↑ ➔ ↑ water vapor (moisture) traveling down resp airway
  • biggest change in terms of relative proportion = CO2
  • O2 & CO2 exchange across pulmonary & systemic capillaries through partial pressure gradients
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15
Q

gas transport

A
  • most O2 transported bound to hemoglobin in erythrocytes: RBC
  • hemoglobin = protein w/ 4 subunits (2⍺ + 2β) each surrounding a heme group (iron center)
    • higher affinity for O2
  • erythrocytes ≠ mitochondria ➞ must use glycolysis ∴ need energy for active pumps
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16
Q

gas transport: O2 vs CO2

A

O2:

  • 98.5% bound to hemoglobin
  • very low solubility in blood
  • can loosely & reversibly bind to hemoglobin

CO2:

  • majority as bicarbonate
  • bicarbonate (60%) > bound to hemoglobin (30%) > physically dissolved (10%)
  • higher solubility
  • HCO3- produced as byproduct from rxn H2O + carbonic anhydrase (ca)
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17
Q

oxygen hemoglobin dissociation curve

A
  • plateau of curve is where PPO2 is high (lungs)
  • steep part of curve (0-60) exists at systemic capillaries where hemoglobin unloads O2 onto tissue cells
  • PPO2 = main factor in determining % hemoglobin saturation
    • ↑ % saturation where ↑ PPO2 (lungs)
    • ↓ % saturation where ↓ PPO2 (tissue cells)
  • O2 dissociates from hemoglobin at tissue cells
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18
Q

the bohr effect

A
  • influence of CO2 and acid on the release of O2
  • CO2/H+ can combine reversibly with Hb at sites other than the O2-binding site ➞ changes the molecular structure of Hb that reduces its affinity for O2
  • ↑ CO2 & H+ at tissues shifts dissociation curve right
  • allows hemoglobin to give up 1 O2 at ↓ PP
  • during exercise less binding to O2 & more binding to CO2
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19
Q

haldane effect

A
  • ↓ O2 in tissues causes Hb to pick up CO2 & H+
  • ↑ O2 in lungs causes release of CO2/H+ from Hb
20
Q

chloride shift (hamberger phenomenon)

A

Cl- moves into RBC to offset HCO3- coming out into plasma

  • HCO3- is more soluble in blood than CO2
  • too much CO2 would change blood pH ➞ HCO3- less harmful
  • carbonic anhydrase catalyzes both formation & dissociation of HCO3- (reversible)
  • facilitates CO2 transport to alveoli
21
Q

sickle cell anemia

A

single V-E mutation in β chain of hemoglobin causes defective rigid mol that makes RBC still & sickle-shaped

  1. defective Hb mol = less efficient binding ∴ less O2 for cells
  2. blocks vessels
  3. ↓ SA:V ratio
  4. more rigid = more prone to break ➞ more rapid turnover of RBC but body cannot replace fast enough ∴ ↓ O2 carrying capacity
22
Q

hypoventilation

A

underventilation results in↑ PCO2 ➞ respiratory acidosis

  • more CO2 = more carbonic acid
  • ex: pneumonia
23
Q

hyperventilation

A

rapid ventilation results in ↓ PCO2 & respiratory alkalosis

  • CO2 (as HCO3-) helps maintain pH in certain ranges ➞ enzymes depend on pH & temp to be optimal
24
Q

respiratory control centers in brain stem

A
  • control by est rhythmic breathing pattern
  • neural networks control rhythmic firing or motor nerves to diaphragm (phrenic nerve) & intercostal muscles
  • medullary respiratory centers
    1. dorsal respiratory group (DRG): inspiratory neurons active in normal quiet breathing
    2. ventral respiratory group (VRG): inspiratory & expiratory neurons activated upon demand
  • pre-botzinger complex: on top of VRG = where rhythm is generated
  • pons respiratory centers (PRG): modulate activity of medullary centers to promote smooth breathing rhythms
  • hering breuer reflex: stretch receptors in smooth muscles of bronchioles that inhibit medullary centers to prevent over-inflation
25
Q

chemical influences on ventilation rate

A

A. pO2: only something strenuous causes ventilation

  • 100➞80 mmHg = no change in ventilation
  • normal pp in alveoli: 104 goes down to 40
  • < 40pp ➞ ventilation

B. pCO2: linear relationship w/ ventilation to get rid of CO2

  • PPCO2: 46 in blood ➞ 40 in alveoli
  • < 40 ➞ ventilation ↓
  • more CO2 ➞ more ventilation

C. pH effects ventilation ➞ ability to get O2

  • blood pH drops too low ➞ acidosis
  • blood pH rises to high ➞ alkalosis
26
Q

chemoreceptors

A

central chemoreceptors:

  • located in medulla near resp control center (brainstem)
  • excitatory input to inspiratory neurons
  • more activation than peripheral

peripheral chemoreceptors:

  1. carotid bodies located in carotid sinus
  2. aortic bodies located in aortic arch
    • chemical factors sense [CO2], [O2], & [H+]
    • only respond to [O2] if PO2 < 40mmHg
    • PO2 influence mostly important in situations like suffocation or high altitudes
      *PO2 doesn’t directly activate resp centers ➞ activates through [H+]
    • both active at all times
27
Q

effect on peripheral chemoreceptor vs central chemoreceptor:

↓ PO2 in arterial blood

A

effect on peripheral chemoreceptor:

  • stimulates only when arterial PO2 < 60mmHg
    • even at 40 O2-hemoglobin saturation ~75%
    • hemoglobin designed to carry a lot of O2 in blood even when PO2 ↓
  • emergency mechanism

effect on central chemoreceptor:

  • directly depresses + resp center itself when < 60 mmHg
  • inhibits system
28
Q

effect on peripheral chemoreceptor vs central chemoreceptor:

↑ PCO2 in arterial blood
(↑H+ in the brain ECF only for central)

A

effect on peripheral chemoreceptor: weakly stimulates

effect on central chemoreceptor:

  • strongly stimulates
  • dominant control of ventilation
  • levels > 70-80 mmHg inhibit resp control centers & central chemoreceptors
  • no CO2 in BBB ➞ [H+] in ECF stimulates central chemoreceptors
29
Q

effect on peripheral chemoreceptor vs central chemoreceptor:

↑ [H+] in arterial blood

A

effect on peripheral chemoreceptor:

  • stimulates
  • important in acid-base balance

effect on central chemoreceptor: no effect ➞ cannot penetrate BBB

30
Q

type 1 alveolar cell

A
  • large cavity that allows gas exchange
  • single layer makes up alveoli walls
31
Q

type II alveolar cell

A

produces alveoli fluid lining with pulmonary surfactants:

  • weak detergent that ↓ surface area to prevent collapse
  • normalizes pressure
  • prevents recoil
  • disrupts H-bonding of water lining alveolar wall (mixture of protein & lipid) to prevent large bubble formation from smaller ones
32
Q

pulmonary surfactants

A
  • in fluid lining of alveoli produced by type II alveolar cells
  • weak detergent that ↓ surface area to prevent collapse
  • normalizes pressure
  • prevents recoil
  • disrupts H-bonding of water lining alveolar wall (mixture of protein & lipid) to prevent large bubble formation from smaller ones
33
Q

tidal volume

A

TV = small amount we actually take in during inspiration/expiration

  • normal breathing
  • V of air entering/leaving during single breath
  • ~500 mL
34
Q

inspiratory reserve volume

A

IRV = extra volume of air that can be maximally inspired over & above TV
* V of air we can use during strenuous situations
* FOF
* exercise
* maximal con-traction of the diaphragm, external intercostal muscles, and accessory inspiratory muscles.

35
Q

inspiratory capacity

A

IC = max volume we can inspire after normal quiet expiration
* IC = IRV + TV
* normal V + extra volume for strenuous situations

36
Q

expiratory reserve volume

A

ERV = extra volume that can be actively expired by maximally contracting the internal intercostals beyond that normally passively expired at the end of a resting TV
* forced expiration after normal expiration

37
Q

residual volume

A

RV = volume left over after max expiration

38
Q

functional residual capacity

A

volume in lungs after normal passive expiration

39
Q

vital capacity

A

VC = maximum V that can be moved out during a single breath following a maximal inspiration
* TLC — minimum amount of air necessary for normal fx
* amount of air we can regulate
* maximum volume change possible within the lungs
* IRV + TV + ERV

40
Q

total lung capacity

A

TLC = maximum volume of air that the lungs can hold
* VC + RV
* dead space = non-fresh air; cannot be used by alveoli ➔ does not provide O2

41
Q

medullary respiratory centers

A
  1. dorsal respiratory group (DRG): inspiratory neurons active in normal quiet breathing
  2. ventral respiratory group (VRG): inspiratory & expiratory neurons activated upon demand
42
Q

pre-botzinger complex

A

where rhythm is generated
* on top of VRG

43
Q

normal breathing process is controlled by

A

dorsal respiratory group (DRG) & ventral respiratory group (VRG)

44
Q

pons respiratory centers (PRG)

A

regulate activity of medullary centers to promote smooth breathing rhythms

45
Q

hering breuer reflex

A

stretch receptors in smooth muscles of bronchioles that inhibit medullary centers to prevent over-inflation

46
Q

dorsal respiratory group (DRG)

A

part of medullary respiratory center consisting of inspiratory normal quiet breathing

47
Q

ventral respiratory group (VRG)

A

part of medullary respiratory center consisting of inspiratory & expiratory neurons activated upon demand

NPB 101 (13 decks)

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