Physiology Flashcards
1
Q
parietal pleural membrane
A
outer membrane of the lung that is against the inner surface of the thoracic cavity
2
Q
visceral pleural membrane
A
membrane that covers the surface of each lung
3
Q
pleural cavity
A
space between the parietal and visceral membranes
4
Q
What is the order of branching in the respiratory tree from largest to smallest?
A
- trachea
- main bronchus
- lobar bronchus
- segmental bronchus
- conducting bronchiole
- terminal bronchiole
- respiratory bronchiole
- alveolar duct
- alveolar sac
- alveolus
5
Q
Conducting zone vs. respiratory zone
A
conducting zone:
-trachea to terminal bronchiole
respiratory zone:
- respiratory bronchiole
- alveolar duct and sac
- alveolus
6
Q
What functions are greatly decreased in the respiratory zone?
A
- smooth muscle
- ability to constrict passages
7
Q
respiratory epithelium in the nasal cavity
A
mucous cells and mucus escalator
8
Q
respiratory epithelium in the pharynx
A
stratified squamous for protection from abrasion and chemical attack
9
Q
respiratory epithelium in the conducting portion of respiratory tract
A
typical respiratory mucosa
10
Q
respiratory epithelium in the bronchioles
A
becomes cuboidal
11
Q
respiratory epithelium in the gas exchange surfaces
A
delicate simple squamous epithelium
12
Q
pneymocytes (3)
A
- Type I alveolar cells
- Type II alveolar cells
- Alveolar macrophages
13
Q
type I alveolar cells
A
form the alveolar wall
14
Q
type II alveolar cells
A
- secrete surfactant
- allows membranes to separate
- continuously released by exocytosis
- aqueous protein-containing hypophase and overlying phospholipid film composed primaryily of dipalmitoyl phosphatidylcholine
15
Q
purpose of surfactant
A
lower surface tension
16
Q
alveolar macrophages
A
phagocytize foreign material such as bacteria
17
Q
pulmonary circulation of low oxygen blood
A
- returned from systemic circulation to RA
- RV to pulmonary artery
- to capillaries in lungs
18
Q
pulmonary circulation of oxygenated blood
A
- from lungs to pulmonary veins to LA
- LV to aorta to systemic circ
19
Q
atmospheric pressure at sea level
A
760 mmHg
20
Q
intrapulmonary pressure
- where
- how does it change
A
- within alveoli
- changes w/ volumes
21
Q
intrapleural pressure
- where
- relation w/ atmospheric pressure
A
- within pleural cavity
- about -4 from atmospheric pressure
22
Q
What are the 3 factors that hold the lungs to the thorax?
A
- surface tension of pleural fluid
-holds membranes together - positive pressure in lungs
-always higher than
intrapleural
-net outward pressure - atmospheric pressure
-exterior force
-higher than subatm. P of intrapleural space
23
Q
What are the 2 factors that pull lungs from thorax?
A
- recoil tendency
- elastic nature of lungs
- always seek smallest size - alveolar surface tension
- draws the alveolus in
- maintaining air in this space prevents collapses
- also fluid from type II cells
24
Q
What is the most important factor in holding the lungs to the thorax?
A
negative pressure of the intraplueral space (positive pressure in lungs)
25
atelectasis
collapse/closure of the lung
26
Boyle's Law
pressure of a gas varies inversely with its volume
27
effects of increasing thoracic volume in all direction
- lowers pressure interiorly
- air rushes in through trachea down its pressure gradient
- results in inspiration
28
effects of relaxation of the thorax
- compresses air inside
- air flows out from this area of increased pressure
- results in expiration
29
Sequence of events in inspiration (5)
1. inspiratory muscles contract
2. thoracic cavity volume increases
3. lungs are stretched; intrapulmonary volume increases
4. intrapulmonary pressure drops
5. air flows into lungs down pressure gradient until intrapulmonary pressure is 0 (equal to atmospheric)
30
Sequence of events in expiration (5)
1. inspiratory muscles relax
2. thoracic cavity volume decreases
3. elastic lungs recoil passively; intrapulmonary volume decreases
4. intrapulmonary pressure rises
5. air flows out of lungs down pressure gradient until intrapulmonary pressure is 0
31
Resistance
the opposition to airflow
32
resistance depends on what?
- diameter of tube
- type of flow: turbinate; laminar
- viscosity of gas (humidity)
33
airflow equation
V = deltaP / R
airflow = pressure gradient / resistance
34
physical factors influencing ventilation through airway resistance
- obstruction
- bronchoconstriction: smooth muscle contraction, parasympathetic control, irritants, RAD
- bronchodilation: smooth muscle relaxation, sympathetic control
35
lung compliance
- ease w/ which lungs can be distended or stretched
| - a measure of the change in lung volume that occurs w/ a change in the intrapulmonary pressure
36
compliance equation
C = delta V / delta P
37
hysteresis
gap between input and output
38
where is airway resistance the highest?
the medium sized bronchi of the conducting zone
39
lung compliance is dependent on what?
elasticity of tissues
40
lung compliance decreases with what? (4)
- decreased lung elasticity such as fibrosis
- obstruction
- alveolar film changes
- impaired thoracic cage flexibility
41
factors influencing ventilation through lung elasticity
- ability of tissues to recoil
- essential to expiration
- COPD reduces recoil d/t deterioration of alveolar walls
42
surface tension
- occurs at fluid-air interface
- liquid molecules are more attracted to each other
- creates tension across liquid surface
- water has high surface tension
43
surfactant
- alveolar film
- secreted from type II alveolar cells
- lipoprotein
- disrupts cohesiveness of water molecules
- decreases surface tension
- prevents alveolar collapse
- reduces energy required to overcome surface tension
44
infant respiratory distress syndrome
- insufficient surfactant in neonate
- incidence decreases w/ increasing gestational age
- 50% in babies born at 26-28 wks; 25% at 30-31 wks
- high HR, RR, cyanosis
- tx: surfactant spray and positive pressure ventilation
45
spirometry
- measuring of breath
- most common PFT
- measures lung function
- specifically the amount (vol.) and/or speed (flow) of air that can be inhaled and exhaled
46
tidal volume (TV)
quiet eupnea
47
inspiratory reserve volume (IRV)
air forced in above TV
48
expiratory reserve volume (ERV)
forced out after exp
49
residual volume (RV)
- remains after forced expiration
| - maintains alveolar patency and prevents lung collapse
50
inspiratory capacity (IC)
- total amount that can be inhaled after tidal expiration
| - TV + IRV
51
Have a general understanding of the amount of air in each pulmonary capacity
- IRV: 3100 ml
- TV: 500 ml
- ERV: 1200 ml
- RV: 1200
- IC: 3600
- FRC: 2400
- VC: 4800
- TLC: 6000
52
functional reserve capacity (FRC)
- amount of air remaining in lungs after tidal expiration
| - ERV + RV
53
vital capacity (VC)
- total amount of exchangeable air
| - TV + IRV + ERV
54
total lung capacity (TLC
sum of all
55
dead space
air which enters the pulmonary space but cannot be used
56
anatomical dead space
- conducting zone
| - 150 ml of tidal volume
57
physiological dead space
- nonfunctioning alveolus
| - d/t mucus or blood flow
58
pulmonary function tests (PFT)
measurement of pulmonary function, dysfunction and efficacy of medication
59
minute respiratory volume (MRV)
- total vol. moved in 1 minute
- TV x breaths per min
- 500 ml x 12 breaths per min. = 6000 ml/min
- rate and depth increases w/ activity
60
forced vital capacity (FVC)
-deep breath and rapid forced exhalation
61
forced exiratory volume (FEV)
- FVC measurements at specific intervals:
- FEV1: volume in first second
- FEV1 FVC ratio (normal is 80%)
62
FEV1 in obstructive diesase
- low and slow
| - ratio = 40%
63
FEV1 in restrictive disease
- low and fast
| - ratio = 88%
64
alveolar ventilation rate
- better index of effective ventilation than MRV
| - subtracts dead space volume
65
What are processes other than breathing that move air?
- cough: forced expulsion of air from lower respiratory tract
- sneeze: forced expulsion of air from upper airways
- hiccup: diaphragm spasms
- crying/laughing: emotionally induced, release of air in short expirations
- yawns: deep inspiration w/ jaw open; ventilates all alveoli
66
Dalton's Law
-total pressure exerted by a mixture of gases is the sum of the pressures of each gas
67
Henry's Law
- the solubility of a gas in a liquid is directly proportional to the pressure of that gas above the surface of the solution
- i.e: dissolves in proportion to its pp
- depends also on the solubility of the gas in liquid
- CO2 is very soluble
68
hyperbaric chamber
- makes use of henry's law
- increase atmospheric pressure
- increases partial pressure of O2
- increasing diffusion into blood
- use in CO poisoning, gas gangene, would healing, decompression sickness
69
properties of gases
atmospheric p. at sea level = 760 mmHg
- N2 (78.6%) - 597
- O2 (20.9%) - 159
- CO2 (0.04%) - 0.3
- H2O (0.46%) - 3.7
70
properties of alveolar gases
- N2 (74.9%) - 569
- O2 (13.7%) - 104
- CO2 (5.2%) - 40
- H2O (6.2%) - 47
71
What is the difference in amount of gases between air and alveolar gas due to?
- gas exchange
- humidification
- mixture of new and residual air
72
diffusing capacity
- diffusing capacity of the lung for a gas is indirectly proportional to the surface area of the alveolar-capillary membrane
- it is inversely proportional to its thickness
73
diffusing capacity equation
DLCO = V / P
74
DLCO (diffusing capacity of lung to CO2)
- a measure of how well oxygen and CO2 are transferred (diffused) b/w the lung and the blood
- CO2 is generally the test gas used to measure
75
When is DLCO reduced?
in diseases that:
1. thicken the membrane (fibrosis)
2. reduce the surface area of membrane (emphysema, cancer)
76
external respiration
- where
- based on what
- occurs at alveolus-capillary junction
| - based on pressure gradients and solubility
77
what is the surface area for diffusion in the lung?
- 300 million alveoli
| - 145m (size of tennis court)
78
ventilation
(V) = air reaching alveolus
79
perfusion
(Q) = gas reaching pulmonary capillaries
80
ventilation perfusion coupling
- V/Q
| - ideally matched
81
VQ scan
- imaging
- inhaled radiolabeled isotope
- gold standard for PE
82
in pulmonary gas exchange, what happens when alveolar O2 is inadequate?
pulmonary vasoconstriction occurs to send blood to more ventilated areas
83
in pulmonary gas exchange, what happens when alveolar CO2 is high?
vasodilation occurs to allow for greater CO2 diffusion from blood
84
internal respiration occurs between ?
between blood and tissues
85
What solves the poor solubility of O2?
hemoglobin
86
At what partial pressure is Hgb saturated?
70 mmHg
87
purpose of the venous reserve
- it can deliver O2 rapidly to tissues in need w/o changing RR or HR
- about 20-25% O2 is unloaded in 1 venous circuit
88
What effect does temp have on hgb affinity for O2?
- as temp increases, affinity for O2 decreases (not linear)
| - decreasing affinity relates to O2 unloading which is desirable in areas of high metabolic activity
89
Bohr effect
- As [H+] increases, pH decreases
- low pH decreases affinity for O2
- metabolically active tissues release more CO2 and H+
- so O2 unloading occurs at active tissues needing it
90
DPG
- diphosphoglycerate
- intermediate of glycolysis in RBCs
- binds Hgb and decreases its affinity for O2
91
as DPG increases, what is the result?
more O2 is available to the tissues
92
hormones that increase RBC activity
- thyroxine
- testosterone
- growth hormone
- catecholamines (epi norepi)
93
what does a left shift indicate in the O2 dissociation curve?
high O2 affinity
94
what does a right shift indicate in the O2 dissociation curve?
lower O2 affinity
95
oxygen saturation
- SaO2
- pulse ox measures peripheral O2 sat as an estimate of percentage of O2 bound to Hgb
- healthy: 96-99%
- <90% is hypoxemia
96
partial pressure oxygen
- PaO2
- low oxygen pressure Hgb tends to be unsaturated
- in cells= 40mmHg
- in blood = 75-100mmHg
97
PaO2 in the oxygen dissociation curve
- at low PaO2, Hgb becomes rapidly saturated w/ O2
| - levels off w/ increasing partial pressures of O2
98
Hgb binding to CO
-Hgb binds CO 200-250 times more radily than with O2
-Hgb completely dissociates the oxygen molecules for the more favorable CO, yeilding HbCO
= hypoxia (w/o cyanosis), HA, confusion, respiratory distress, coma, death
99
Hgb CO reaction equation
HbO2 + CO HbCO + O2
100
what is the source of carbon dioxide?
- cellular respiration
| - 200 mL produced per min
101
3 forms of CO2 transport
- dissolved in plasma (7-10%)
- carbaminohemoglobin (20-30%)
- bicarbonate ion (60-70%)
102
carbaminohemoglobin
- hgb can bind to 4 CO2 molecules
- in absence of O2, unbound hgb molecules have greater chance of becoming carbaminohemoglobin
- distinctive blue color contributes to dark red color of low O2 in venous blood
103
bicarbonate ion forms d/t what?
enzymatic activity of carbonic anhydrase
104
equation yielding bicarb
CO2 + H2O H2CO3 HCO3- + H+
carbon dioxide + water carbonic acid bicarb + hydrogen
105
Bohr efffect
generation of H+ enhances O2 unloading
106
Haldane effect
- deoxygenation of Hgb increases its ability to bind CO2
- Hgb uptakes protons
- buffering pH in the RBC
107
pH blood values
- normal: 7.35-7.45
- acidosis: <7.35
- alkalosis: >7.45
108
acid base disorders are changes in what? (3)
- blood pH
- arterial pCO2
- blood HCO3
109
actual changes in pH depend on what?
the degree of physiologic compensation
110
respiratory causes of acid-base balance disorders
- inadequacy of respiratory function
| - usually pCO2 imbalance
111
metabolic cause of acid-base balance disorders
any abnormalities resulting in pH changes except those caused by pCO2 imbalance
112
compensation mechanisms
- respiratory changes
- buffering systems in blood and tissues
- kidney absorption and secretion
113
metabolic acidosis can be d/t: (4)
- increased acid production
- acid ingestion
- decreased renal acid secretion
- GI or renal HCO3 loss
114
metabolic alkalosis causes: (2)
- acid loss
| - HCO3 retention
115
respiratory acidosis
- blood pH <7.35
- pCO2 > 45mmHg (hypercapnia)
- CO2 accumulated in blood d/t hypoventilation
- pneumonia, CF, emphysema, overdose, brainstem dysfunction
116
compensation of respiratory acidosis (respiration and renal)
- respiration: increases to allow CO2 ventilation
- kidney:
- renal tubule cells have carbonic anhydrase
- retain bicarb
- eliminate H+
117
respiratory alkalosis
- blood pH >7.45
- pCO2 <35 (hypocapnia)
- CO2 decreased in blood d/t hyperventilation
- pneumonia, reactive airway dz, high altitude, anxiety, brain stem injury
118
compensation of respiratory alkalosis (respiration and renal)
- respiration: decreases to allow CO2 accumulation
- kidney:
- retain H+
- eliminate bicarb
119
hypoxia
oxygen deficit at tissue level
120
most common types of hypoxia
- hypoxemia: low arterial O2; pneumonia, high altitude;
- anemic hypoxia: adequate O2, low Hbg
- ischemic hypoxia: slowed circulation, heart failure, shock
- histotoxic hypoxia: poisoning i.e cyanide
121
hypoxemia S/S
- SOB, dyspnea
- HA
- fatigue/lethargy
- severe mood changes or irritability
- cyanosis
- digital clubbing (chronic)
122
causes of hypoxemia (decreased arterial pO2)
- ARDS
- asthma
- CO poisoning
- congenital heart disease
- COPD
- high altitude
- interstitial lung disease
- meds
- pneumonia
- pneumothorax
- pulmonary edema
- PE
- pulmonary fibrosis
- sleep apnea
123
high altitude causing hypoxemia
- composition of gases is unchanged by atm pressure but partial pressures are decreased
- as pO2 falls, ventilation increases, pCO2 falls and respiratory alkalosis can occur
124
altitude sickness
- irritability
- mental status change
- N/V
- HA
- LOC
- coma
- death
125
acclimatization to high altitude
- DPG increases resulting in O2 unloading
- ventilatory response decreases after about 4 d
- EPO secretion increases RBC
126
hypoxemia d/t venous to arterial shunts
- cardiovascular abnormalities
- ie. interseptal defect
- large amount of low O2 blood shunts from RV to LV bypassing pulmonary oxygenation
- chronic hypoxemia and cyanosis
- O2 administration has little effect
127
what is the most common cause of hypoxemia?
ventilation/perfusion imbalance
128
ventilation/perfusion imbalance causing hypoxemia
- defects in ventilation (low V/Q ratio): chronic bronchitis, RAD, acute pulmonary edema, hepatopulmonary syndrome of liver failure
- defects in perfusion (high V/Q ratio): PE, emphysema
129
anemic hypoxia
- decreased Hg
- compensated by increased DPG production
- shifts dissociation curve to right
130
CO poisoning hypoxia
- decreases O2 sat
| - fatal is >70% COHgb
131
ischemic hypoxia
- slowed circulation therefore poor delivery
- shock
- heart failure
- ARDS
132
histotoxic hypoxia
- decrease in oxidative processes
- i.e: toxin like cyanide
- treat w/ methylene blue
- binds Hgb then cyanide to form cyanomethemoglobin which is non toxic
133
decompression sickness
- result of increases pressure esp when diving
- inert gases (N2) will dissolve in plasma
- forms gas bubbles on ascent
- decompress on ascent to allow gases to be unloaded by lungs
134
Henry's law
-increased pressure increases partial pressures (think decompression sickness)
135
onset of decompression sickness symptoms
- w/i 1 hr: 42%
- w/i 3 hrs: 60%
- w/i 8 hrs: 83%
- w/i 24 hrs: 98%
although onset of DCS can occur rapidly, in more than 1/2 cases they don't occur for at least an hour
136
top 3 most common symptoms of decompression sickness?
1. local joint pain
2. arm symptoms
3. leg symptoms
others: dizziness, paralysis, SOB, extreme fatigue, collapse/unconsciousness
137
hyperoxia
- oxygen toxicity
| - O2 at pressures above normal
138
3 settings for hyperoxia
1. underwater diving
2. hyperbaric O2 therapy
3. provision of supplemental O2 (particularly to premature infants)
139
effects of hyperoxia
- CNS: convulsions followed by LOC
- Pulmonary: SOB, dyspnea
- Ocular: myopia, retinal detachment, damage
140
hypercapnia
- retention of CO2
- usually d/t hypoventilation
- stimulates respiration to blow off CO2
- respiratory acidosis
141
S/S and causes of hypercapnia
S/S: confusion, decreased sensory acuity, respiratory depression and coma
causes: heart failure, sleep apnea, LOC
142
hypocapnia
- depletion of CO2
- secondary to hyperventilation
- respiratory alkalosis
143
S/S and causes of hypocapnia
- S/S:
- cerebral vasoconstriction leads to ligh headedness, numbness and tingling
- tetany
- Cvostek sign d/t increases plasma Ca2+
- Causes: hyperventilating; brainstem dysfunction
144
What controls the regulation of respiration?
-two separate neural control centers; voluntary and involuntary
145
voluntary system control center
cerebral cortex to respiratory motor nerves via the corticospinal tracts
146
involuntary system control center
- medulla and pons of brain stem
- sets pace
- appropriating responses to sensory info from chemoreceptors and mechanoreceptors
147
what is found within the medullary center?
- VRG
| - DRG
148
ventral respiratory group (VRG)
- contains both inspiratory and expiratory neurons
- secondarily responsible for initiation of inspiratory activity after the DRG
- pre-botzinger complex
- expiratory respiratory group
149
pre-botzinger complex
- in VRG of medulla
- pacemaker of breathing
- neurons send rythmic signals
- results in expansion of rib cage, air enters
- cycles 12-18 times per min
- inspiration 2 sec
- expiration 3 sec
150
neuron signals from the pre-botzinger complex (3)
- phrenic nerve: contraction of diaphragm
- intercostal nerve: external intercostals
- hypoglossal nerve: tongue
151
expiratory respiratory group
- located in the VRG of medulla
- maintains tone
- increases contraction of inner intercostals and abs for forced exhalation
152
dorsal respiratory group (DRG)
- primarily responsible for the generation of inspiration
- stimulated via the apneustic center in the lower pons and is also a part of the solitary tract (responsible for appropriating responses to sensory info from chemo and mechanoreceptors)
153
DRG is inhibited by ?
pneumotaxic center
154
pontine control centers
- appear to modulate medullary centers
- if medullary-pontine connection is transected, breathing is rhythmic by occurring in gasps
- responsible for transition b/w inhalation and exhalation
155
What are the 2 pontine control centers?
- apneustic center
| - pneumotaxic center
156
apneustic center
- excitatory to medullary inspiratory center (DRG)
- creates inspiratory drive
- prolongs inspiratory phase
- receives inhibitory signals from pneumotaxic center
157
pneumotaxic center
- location superior to apneustic
- inhibitory to apneustic center
- inhibitory to DRG medullary center
- prevents over inflation
158
factors influencing rate and depth of breathing
- irritant reflexes
- hering-breuer reflex (inflation and deflation)
- medullary chemoreceptors (central receptors)
- carotid and aortic bodies
159
irritant reflexes
- particles such as debris, dust, lint, fumes
- stimulate release of histamine by granulocytes in airway -stimulate irritant receptors
- vagus mediated response: sneeze, cough, bronchocontricition
160
Hering-Breuer reflex
- mechano or stretch receptors in vesceral pleura and airways
- inflation reflex
- deflation reflex
161
inflation hering-breuer reflex
- prevents over-inflation of lung
- receptors respond to excessive stretching of lung during large inspirations
- action potential through vagus n. to inspiratory area in the medulla
162
deflation hering-breuer reflex
- shorten exhalation when the lung is deflated
- by stimulation of stretch receptors or stimulation of proprioceptors activated by lung deflation
- impulses travel afferently via Vagus and pneumotaxic centers of pons
163
medullary chemoreceptors i.e central receptors
- located on ventral surface of medulla, bathed in CSF
- sensitive to pH
- CO2 diffuses into CSF, carbonic anhydrase releases H+ and HCO3
- hypercapnia
- hypocapnia
164
carotid and aortic bodies
- perpherial receptors
- sensitive to pO2 <60mmHg
- aortic impulses ascend afferent vagal nerves to medulla
- carotid impulses ascend afferent hypoglassal fibers
- result is medullary stimulated ventilation to increase O2
165
there is an increase in ventilation during exercise d/t:
- physic stimulation
- stimulation of cortical motor activation of skeletal muscle and respiratory centers
- proprioceptors in muscles, tendons, and joints send excitatory impulses to respiratory center
166
ventilation plateaus during exercise d/y:
- central stimulatory effects of rising body temp
- sympathetic nervous system stimulation
- decreased activity shuts down respiratory stimulation
167
skeletal muscle energy/oxygenation
- skeletal muscle has myoglobin (hold 1 O2)
- muscle cell energy needs to exceed ability to oxidatively phosphorylate ADP
- anaerobic respiration ensues
168
fatigue and exhaustion during exercise
- consumption of resources
- increased neural inputs to brain
- lactate increase
- temp increase
- dyspnea
- pain
169
breathing pattern imbalances
- Cheyne Stokes
- Kussmaul breathing
- sleep apnea
170
cheyne stokes
- rapid breathing d/t hypoxia followed by apnea d/y hypercapnia
- seen in CHF, uremia, bain dysfunction
171
Kussmaul breathing
- deep and labored breathing pattern
- often associated w/ severe metabolic acidosis, particularly DKA but also kidney failure
- form of hyperventilation
- in metabolic acidosis: first breathing is rapid and shallow, then gets deep and labored and gasping
172
sleep apnea
- obstructive most common, can be central
- pharyngeal muscles relax or genioglossus pulls tongue foward
- during REM, muscles are most tonic
- airway obstruction and reduced effort awaken pt
- fatigue, HA, snoring, reduced learning
- tx: CPAP
173
sleep apnea is associated with:
- HTN
- obesity
- ETOH/drug use
