Cardiopulmonary Anatomy and Ph Flashcards

Terms Definitions
Describe 3 functions of the larynx
1. Passageway of air between the pharynx and the trachea.2. Protective mechanism against aspiration of solids and liquids3. Generates sounds for speech
Describe the functions of the epiglottis
prevents aspiration of food and liquids by covering the opening of larynx during swallowing
What is the average length and diameter of the adult trachea?
11-13 cm long; 1.5 - 2.5 diameter
where does the conducting zone end and the respiratory zone begin?
terminal bronchiole ends conducting zone and respiratory bronchioles begin respiratory zone
List the structures that make up promary lobule for gas exchange
respiratory bronchioles, alveolar ducts, alveolar clusters that originate from single terminal bronchiole are primary lobule
Define the function of alveolar macrophages
removes bacteria and other foreign particles; type III originated from stem cells, reproduce within the lungs
Describe the function of Type II cells
granular pneumocyte 5% total alveolar surface primary source of pulmonary surfactant and decreases surface tension of fluid that lines alveoli
Distinguish by name, the different neural tramsmitters that are reeleased by sympathetic and parasympathetic nervous systems
sympathetic - norepinephrine and epinephrineparasympathetic - acetylcholine
function of pleural fluid
parietal lines thoraxvisceral attached to surface of lungtwo pleura held together by serous fluid which allows them to slide across each other during inspiration and expiration
Identify parts that make up sternum
top is manubrium sterni, middle is body and bottom is xiphoid process
Identify nerves that innervate teh diaphragm
Terminal branches of phrenic nerves which leave spinal cord between 3rd and 5th cervical segments, supply primary motor innervation to each hemidiaphragm. Lower thoracic nerves contribute to motor innervatio nof each hemidiaphragm
What is lung compliance and how is it expressed?
How readily the elastic force of the lungs accepts a volume of inspired air expressed in liters per centimeter of water pressure (L/cm H2O)
What is formula for lung compliance
CL = change in volume expressed in Liters divided by change of pressure expressed in cm H2O
What is Hooke's Law?
when a truly elastic body, like a spring, is acted on by 1 unti of force, the elastic body will stretch 1 unit of length and when acted on by 2 units of force it will stretch 2 units of length and so force
what is the formula that expresses Hooke's law w/ regard to elastance?
Elastance = change in pressure divided by change in volume
What is the purpose of pulmonary surfactant?
significantly lowers alveolar surface tension
Where is pulmonary surfactant produced?
alveolar type II cells
What is pulmonary surfactant composed of?
phospholipids 90%protein 10%
What is the primary surface tension lowering chemical in pulmonary surfactant?
phospholipid dipalmitoyl phosphatidylcholine (DPPC)
During exhalation, what happens to alveolus?
decreases in size
When alveolus decreases in size during exhalation, what happens to the proportion of DPPC to alveolar surface area?
increases and this increases the effect of DPPC molecules and causes alveolar surface tension to decrease
What happen sto the alveolus during inhalation?
alveolus increases
When alveolus increases during inhalation, what happens to DPPC?
relative amount of DPPC to alveolar surface area decreases because the number of surfactant molecules does not change when size of alveolus changes which decreases the effect of DPPC molecules and causes alveolar surface tension to increase
What is Laplace's Law?
distending pressure required to maintain size of bubble professively decreases as bubble size increases
What happens in the absence of pulmonary surfactant?
alveolar surface tension increases to the level it would naturally have and distending pressure necessary to overcome recoil forces of liquid film coating the small alveoli is very high
what is complete alveolar collapse
What is the location of anatomical dead space and how is its volume assessed?
conducting airways; nose, mouth, pharynx, laryx, lower airways down to but not including respiratory bronchioles1ML normal body weight 150 lb person volume anatomical dead space is 150 mL
What are 5 general causes of pulmonary surfactant deficiency?
acidosishypoxiahyperoxiaatelactasispulmonary vascular congestion
What are 8 specific causes of pulmonary surfactant deficiency?
ARDSIRDSpulmonary edemapulmonary embolismpneumoniaexcessive pulmonary levage or hydrationextracorporeal oxygenation
Define alveolar dead space
alveolus is ventilated but not perfused with pulmonary blood thus air that enters alveolus is not effective in terms of gas exchange because there is no pulmonary capillary blood flow. amount of alveolar dead space is not predictible
Cheyne Stokes
10-30 seconds of apnea followed by gradual increase in volume and frequency of breathing followed by gradual decrease in volume of freathing until another pariod of apnea occurs. associated with cerebral disorders.depth of breathing increases, oxygen falls and carbon dioxide rises
Kussmaul's Respiration:
increased depth (hyperpnea) and rate of breathing causes carbon dioxide to decline and oxygen to incraseassociated with diabetic acidosis (ketocidosis)
What is the normal barometric pressure at sea level?
760 mmHg
What is tidal volume?
The volume of air that normally moves into and out of the lungs in one quiet breath
define ERV - expiratory reserve volume
maximum volume of air that can be exhaled after a normal tidal exhalation
Tidal Volume
volume of air that normally moves into and out of the lungs in one quiet breath
Inspiratory reserve volume maximum volume of air that can be inhaled after a normal tidal volume exhalation
Expiratory reserve volume maximum volume of air that can be exhaled after normal tidal volume exhalation
Vital lung capacity - maximum volume of air that can be exhaled after maximal inspiration - IRV + Vt + ERV
Functional Residual Capcity volume of air remaining in the lungs after a normal exhalation - ERV + RV
Under normal circumstances, what should the patient's FEV1% be?
83% or greater
What are the most commonly used pulmonary function measurements to determine the severity of patient's obstructive pulmonary disease and to distinguish between an obstructive and restrictive lung disorder
FEV, FEV1 and FEV1%
What ratio is the comparison of the amount of air exhaled in one second to the total amount exhaled during an FVC maneuver
In obstructive lung disorders, what happens to the FEV1 and the FEV1%
In restrictive lung disorders, what happns to the FEV1, and the FEV1%
the FEV1 is downbut the FEV1% is normal or increased
What is the majority of blood cells
erythrocytes - red blood cells
What is is percentage of red blood cells in relation to the total blood volume
What is normal hematocrit in males and females?
approx 45% in adult male and 42% in adult female
What is the heart wall is composed of
epicardium, myocardium and endocardium
What is the visceral layer of the pericardium, composed of single sheet of squamous epithelial cells overlying delicate connective tissue
What is thick contractile middle layer of uniquely constructed and arranged muscle cells
What is the bulk of the heart, layer that actually contracts
contractile tissue of the myocardium is composed of what?
fibers with the characteristic cross-striations of muscular tissue.
What is the internal structure of myocardium?
cardiac muscle cells are interconnected to form a network spiral or circular bundles which effectively connect all the parts of the heart together. collectively teh spiral bundles form a dense network called fibrous skeleton of the heart which reinforces the internal portion of the myocardium. modified tissue fibers of the myocardium constitue the conduction system of the heart SA node, AV node, AV bundl of His and Purkinje fibers
What is glistening white sheet of squamous epithelium that rests on a thin connective tissue layer. Located in the inner myocardial surface, it lines the heart's chambers.
What is contains small blood vessels and a few bundles of smooth muscles. it is continuous with the endothelium of the great blood vessels - superior and inferior vena cava
Right atrium receives venous blood from where?
inferior vena cava and superior vena cava
Right atrium receives venous blood from inferior vena cava and superior vena cava and this blood is what in terms of O2 and CO2
low in oxygen and high in carbon dioxide
Where does the tricuspid valve lie, held in place by and secured by?
between the right atrium and right ventricle and the leaflets are held in place by chordae tendinae, secured by papillary muscles
What happens when ventricles contract?
tricuspid valve closes and blood leaves the right ventricle through the pulmonary trunk
After blood passes through the lungs, it returns to the what by way of what?
the left atrium by way of pulmonary veins
After blood passes through the lungs, it returns to the left atrium by way of pulmonary veinsThis returning blood is high what and low in what?
high in oxygen and low in carbon dioxide
Bicuspid/mitral valve lies where and does what?
between left atrium and left ventricle and prevents blood from returning to left atrium during ventricular contraction
left ventricle pumps blood through what?
ascending aorta
The aortic valve lies where and does what?
at the base of the aorta that closes when teh ventricles relax and prevents backflow of blood into the left ventricle
When ventricles contract (ventricular systole) what happens?
is forced into the pulmonary artery and the aorta and the pressure in these arteries rises sharply.
What is is the systolic pressure
the maximum pressure generated during ventricular contraction
What happens when the ventricles relax (ventricular diastole)
the arterial pressure drops
what is normal pressure
normal pressure is about 120 mmHg and normal diastolic pressure is about 80 mmHg.
what is stroke volume?
is the volume of blood ejected from the ventricle during each contraction
What are Stroke volume ranges
Stroke volume ranges between 40mL and 80mL.
What is Cardiac Output
Cardiac Output is the total volume of blood discharged from the ventricles per minute
How is CO is calculated
by multiplying stroke volume by heart rate per minute (CO = SVxHR)
What does CO directly influence
blood pressure - when stroke volume or heart rate increases, blood pressure increases and when stroke volume or heart rate decreases, blood pressure decreases
what is normal adult blood volume?
Normal adult volume is 5L and 75 percent is systemic, 15 percent in the heart, 10 percent in pulmonary circulation - Overall 60% in veins and 10 percent in arteries
What is the double-walled sac the heart is enclosed in?
What is the primary function of the fibrous pericardium?
protect the heart, anchor the heart to surrounding structures, prevent the heart from overfilling
What is the inner wall of the heart called?
serous pericardium
The inner wall of the heart called the serous pericardium is composed of what two layers?
parietal and visceral pericardium
What is the visceral layer of the pericardium called?
the epicardium
What is the epicardium composed of?
single sheet of squamous epithelial cells overlying delicate connective tissue
What does the myocardium consist of?
cross-striated tissue fibers that form a network of spiral bundles throughout the internal portion of the heart
Where is the endocardium located?
inner myocardial surface and lines the heart chambers
Blood supply that nourishes the heart originates directly from the aorta by means of which two arteries?
left coronary arteryright coronary artery
The left coronary artery divides into which two branches?
circumflex branch and anterior interventricular branch
The right coronary artery supplies the right atrium and then divides into which branches?
marginal branch and posterior interventricular branch
Where does venous blood from the posterior position of the heart cleected by?
middle cardiac vein
Where does venous blood from the anterior side of the heart empty into?
The great and middle cardiac veins merge and empty into a large venous cavity within the posterior wall of the right atrium called what?q
coronary sinus
A small amount of venous blood is collected by what vein which empties directly into both the right and left atrium?
thebesian vein
Where does the right atrium receive venous blood?
inferior and superior vena cava
A small amount of cardiac venous blood enters the right atrium by means of which vein?
thebesian vein
which one-way valve lies between the right atrium and right ventricle
tricuspid valve
What are the tricuspid leaflets held in place by?
chordae tendinae
The chordae tendineae of the tricuspid leaflets are secured to the ventricular wall by what?
papillary muscles
When the ventricles contract, the tricuspid valve closes and blood leaves the right ventricle thorugh what and enters the lungs by way of what?
pulmonary trunkpulmonary arteries
What valve separates the right ventricle from the pulmonary trunk?
pulmonary semilunar valve
After blood passes through the lungs, it returns to the left atrium by way of what?
pulmonary veins
What valve lies between the left atrium and left ventricle
bicuspid valve
What does the left ventricle pump blood through?
ascending aorta
What is the maximum pressure called that is generated during ventricular contraction?
systolic pressure
When the ventricles relax, the lowest pressure that remains in teh arteries prior to the next ventricular contraction is called what?
diastolic pressure
Compared to the pulmonary circulation, the minimum pressure in teh systemic system is how many times greater?
10 times greater
What are the normal stroke volume ranges?
40 mL and 80 mL
What is the total volume of blood discharged from teh ventricles per minute called?
cardiac output
with regard to total blood volume of normal adults, how much is systemic circulation, in the heart and in pulmonary circulation?
75% systemic circulation15% in the heart10% in pulmonary circulation
Overall, how much blood is in the veins and how much is in the arteries?
60% in the veins, 10% in the arteries
Name the chemical components of blood
water, proteins (albumins, globulins, fibrinogen), electrolytes (cations like Na, K, Ca, Mg; anions like Cl, Po, So HCO), Food substances (amino acids, glucose/carbs, lipids, individual vitamins), Respiratory gases, individual hormones, waste products (urea, creatine, uric acid, bilirubin)
Name the chemical components of blood
water, proteins (albumins, globulins, fibrinogen), electrolytes (cations like Na, K, Ca, Mg; anions like Cl, Po, So HCO), Food substances (amino acids, glucose/carbs, lipids, individual vitamins), Respiratory gases, individual hormones, waste products (urea, creatine, uric acid, bilirubin)
What is another word for platelet?
Dissolved: When a gas like oxygen enters the plasma, what happens?
it maaintains its precise molecular structure and moves freely throughout the plasma in its normal gaseous state
pH - normal arterial and venous ranges
a (arterial) 7.35 - 7.45v (venous) 7.3 - 7.4
Pco2 - normal arterial and venous ranges
a 35-45 mmHgv 42-48 mmHg
Clinically, which portion of the oxygen transport system is measured to assess the patient's partial pressure of oxygen?
dissolved 02
what is Vol% defined as?
amount of O2 in milliliters that is in 100ml of blood
how many million hemoglobin molecules is contained within each red blood cell?
What is adult Hemoglobin designated as?
In the normal adult hemoglobin, how many heme groups are there?
When two oxygen molecules are bound to one Hb molecule, the Hb is said to be how much saturated?
What is hemoglobin bound to oxygen called?
hemoglobin not bound with oxygen is called what? (two variations)
reduced hemoglobin or deoxyhemoglobin
Is the amount of oxygen bound to hemoglobin directly or indirectly related to partial pressure of oxygen?
What does the globin portio of each hemoglobin molecule consist of?
four amino acid chains (polypeptide chains) that collectively constitute a globin
how many alpha and gamma chains does fetal hemoglobin contain?
2 alpha chains and 2 gamma chains
What is hemoglobin changed from teh ferrous state to ferric state known as?
What is the normal hemoglobin values for women, men and infants?
women: 12-15 g% Hbmen: 14-16 g%Hbinfants: 14-20 g% Hb
At a normal arterial oxygen pressure, the hemoglobin saturation is only 97% because of what normal physiological shunts?
thebesian venous drainage to left atriumbronchial venous drainagealveoli that are underventilated relative to pulmonary blood flow
What does the oxygen dissociation curve represent?
percent of hemoglobin that is chemically bound to oxygen at each oxygen pressure
Why is the flat portion of the dissociation curve clinically significant?
hemoglobin has an excellent safety zone for the loading of oxygen in the lungsdiffusion of oxygen during the transit time hemoglobin is in the alveolar-capillary system is enhancedincreasing the P02 beyond 100 mmHg adds very little additional oxygen to the blood
Why is the steep portion clinically significant?
P02 reductions below 60 mmHg indicate a rapid decrease in the amount of oxygen bound to hemoglobinlarge amount of oxygen
What does P50 represent?
partial pressure at which the hemoglobin is 50% saturated with oxygen
What is the normal pressure in mmHg of P50?
27 mmHg
What happens to the P50 when oxygen dissociation curve shifts to the right and why?
increasesaffinity for oxygen decreases therefore pressure required to maintain same oxygen concentration increased
When the oxygen dissociation curve shifts to the left, what happens to the p50?
list factors that shift oxygen dissociation to the left
increased pHdecreased PCO2decreased temperaturedecreased DPGHbFCoHb
List factors that shift the oxygen dissociation curve to the right
decreased pHincreased Pco2increased temperatureincreased DPG
increased pH does what to the P50 and decreased pH does what to the p50?
increased pH shifts the oxygen dissociation curve to the leftdecreased pH shifts oxygen dissociation curve to the right
describe the oxygen dissociation curve shift with regard to both increased and decreased PCO2
decreased PCO2 shifts to the left, increased PCO2 shifts to the right
describe effect on dissociation curve with regard to temperature
decreased temperature shifts to leftincreased temperature shifts to the right
describe DPG (2,3 diphosphoglycerate) (metabolic intermediary formed by RBCs during anaerobic glycolysis) with regard to effect on dissociation curve
decreased DPG shifts to the leftincreased DPG shifts to the right
What effect does HbF have on dissociation curve
shifts to left
what effect does COHb have on dissociation curve?
shifts to the left
Describe the Bohr effect:
The effect of Pco2 and pH on the oxyhemoglobin curvemost active in the capillaries of working muscles, particularly the myocardium
What stimulates the bone marrow to increase RBC production and when does this occur?
When pulmonary disorders produce chronic hypoxemia, the hormone erythropoietin responds by stimulating RBC production
What is RBC production known as?
What is an increased level of RBC?
What is an adaptive mechanism designed to increase the oxygen-carrying capacity of blood?
What is the increased oxygen-carrying capcity in polycythemia offset by?
increased viscocitywhen hematocrit reaches 55-60 percent, the increased viscocity requires a greater driving pressure to maintain a given flow.
What happens because of increased viscocity associated with plycythemia?
work of the right an dleft ventricles must increase in order to generate the pressure needed to overcome the increased viscocity which can ultimately lead to left ventricular hypertophy and failure and to right ventricular hypertrophy, and cor pulmonale.
What is hypoxic hypoxia?
PzO2 and CaO2 are abnormally low
What are some conditions, besides pulmonary shunting, that can cause hypoxic hypoxia
low alveolar oxygendiffusion impairmentventilation perfusion (V/Q ratio) mismatch
What are two conditions that can cause anemic hypoxia?
low amunt of hemoglobin in blooddeficiency in the ability for hemoglobin to carry oxygen
Circulatory hypoxia
condition in which the arterial blood that reaches teh tissue cells may have a normal oxygen tension and content but the blood is not adequate to meet tissue needs
What are two major forms of circulatory hypoxia?
stagnant hypoxia and arterial venous shunting
What is histotoxic hypoxia
any condition that impairs the ability of tissue cells to utilize oxygen
blue-gray or purplish discoloration seen on mucus membranes, fingertips and toes
carbonic acid
hydrochloric acid
sodium bicarbonate
sodium acid phosphate
sodium alkaline phosphate
List the ways carbon dioxide is transported in the blood
Plasma - carbamino compound, bicarbonate, dissolved CO2Blood Cells - dissolved CO2, cabamino Hb, bicarbonate
how the majority of Carbon Dioxide transported, what percent?
Most is bicarbonate - 63%
what is the Haldane Effect
The fact that deoxygenated blood enhances the loading of carbon dioxide
What are electrolytes?
Electrolytes are ions cabable of conducting a current in solution
What is a buffer?
A buffer is a substance capable of neutralizing both acids and bases without causing an appreciable change in the original PH
What is a strong acid?
A Strong Acid is an acid that dissociates completely into H+ and an anion
What is a weak acid?
A Weak Acid is an acid that dissociates only partially into ions
What is a strong base?
A strong base is a base that dissociates completely
what is a weak base?
a weak base is a base that reacts with water to form OH- in equilibrium ; partial dissociation
What is a dissociation constant?
a dissociation constant refers to weak acid or base systems that have an equilibrium between molecular form and its ion
What is a pH of 7
What is a pH less than 7?
What is a pH greater than 7?
In chemistry, what is pH defined as
negative logarithm to the base of 10 of the hydrogen ion concentration
What does an acid donate
hydrogen ions
what does a base accept?
hydrogen ions
What are the three mechanisms that maintain the narrow pH range
buffer system of the blood, respiratory ability to regulate elimination of CO2, renal ability to regulate excretion of hydrogen and reabsorption of bicarbonate ions.
What is the most important buffer system in respiratory physiology
carbonic acid/sodium bicarbonate
During acute ventilatory failure (hypoventilation), the blood PcO2:
During acute ventilatory failure (hypoventilation), the blood H2CO3:
During acute ventilatory failure (hypoventilation), the blood HCO3:
During acute ventilatory failure (hypoventilation), the blood HCO3- to H2CO3 ratio:
During acute ventilatory failure (hypoventilation), the blood pH:
In chronic ventilatory failure, the kidneys work to correct the pH status by:
retaining HCO3
In chronic ventilatory failure, partial or comlete renal compensation can be verified when the HCO3- and pH readings on the Pco2/HCO3-/pH nomogram are
greater than expected for a particular Paco2
During acute alveolar hyperventilation, what happens to the blood Pco2:
During acute alveolar hyperventilation, what happens to the blood H2CO3:
During acute alveolar hyperventilation, what happens to the blood H2CO3:
During acute alveolar hyperventilation, what happens to the blood HCO3:
During acute alveolar hyperventilation, what happens to the blood HCO3 to H2co3 ratio:
During acute alveolar hyperventilation, what happens to the blood pH:
In chronic alveolar hyperventilation, the kidneys work to correct the pH status by:
excreting HCO3-
In chronic alveolar hyperventilation, partial or complete renal compensation can be verified when the HCO3- and pH readings are:
less than exprected for a particular Paco2
As a general rule, the kidneys do not overcompensate for abnormal pH - true or false?
When matabolic acidosis is present, the HCO3- and pH readings are
less than expected for a particular paCo2
Identify common causes for metabolic acidosis and alkalosis
three common causes of metabolic acidosis:lactic acidosis (anaerobic metabolism due to unavailability of oxygen)ketoacidosis (insulin i slow, serum glucose cannot easily enter tissue cells for metabolism therefore alternate metabolic processes that produce ketones is utilized)renal failure (accumulation of hydrogen ions)
what happens to the ventilatory response to a metabolic acidosis condition?
When metabolic alkalosis is present, the HCO3- and pH readings are:
greater than expected for a particular Paco2
common causes of metabolic alkalosis
hypokalemia - depletion of body potassium that can occur from several days of intravenous therapy without adequate replacement of potassium, diuretic therapy and diarrhea - hypochloremia - chloride ion concentration decreases, bicarbonate ions increase in an attempt to maintain normal cation balance in blood serumgastric suction or vomiting - stomach acids depletedexcessive administration of corticosteroids - large dosses of sodium-retaining corticosteroids can cause the kidneys to accelerate the excretion of hydrogen ions and potassium excessive administration of sodium bicarbonate
What is Value for normal V/Q ratio
4:5 or .8
What are pulmonary disorders that increase the V/Q ratio?
pulmonary embolipartial or comlte obstruction in the pulmonary artery or some of the arterioles (atherosclerosis collagen disease)extrinsic pressure on the pulonary vessels (pneumothorax, hydrothorax, presence of tumor)destruction of the pulmonary vessel decreased cardiac output
In disorders that diminish pulmonary ventilation, the affected lung area receives little or no ventilation in relation to blood flow. What does this do to the V/Q ratio?
When the V/Q ratio decreases, what happens to PAo2 and PCO2
PAO2 decreases and PACO2 increases
What are Pulmonary disorders that decrease the V/Q ratio
obstructive lung disorders (emphysema, bronchitis, asthma)restrictive lung disorders (pneumonia, silicosis, pulmonary fibrosis)hypoventilation from any cause
What molecule easily diffuses across the blood-brain barrier
blood brain barrier is very permeable to CO2 moleculesblood brain barrier is relatively impermeable to H+ and HCO3 ions
What is the most powerful stimulus known to influence the medulla and what is responsible for monitoring hydrogen ions in the CSF?
Hydrogen ions in the CSF are the most powerful stimulus known to influence the respiratory components of the medulla. Central chemoreceptors are responsible for monitoring hydrogen ion concentration in the CSF.
How do central chemoreceptors regulate ventilation?
Central chemoreceptors regulate ventilation through the indirect effects of CO2 on the pH of the CSF
What are peripheral chemoreceptors sensitive to?
Peripheral chemoreceptors are special oxygen-sensitive cells that react to the reductions of oxygen levels in the arterial blood
When are chemoreceptors activated?
chemoreceptors are not significantly activated until oxygen content of inspired air is low enough to reduced the PaO2 to 60 mm Hg (SaO2 about 90%)
What are peripheral chemoreceptors specifically sensitive to and relatively insensitive to?
Peripheral chemoreceptors are specifically sensitive to the Po2 of the blood and relatively insensitive to oxygen content of the blood
There are certain conditions where the Pao2 is normal (therefore peripheral chemoreceptors are not stimulated) yet oxygen content of the blood is dangerously low. What are they?
Such conditions include chronic anemia, carbon monoxide poisoning and methemoglobinemia
Name the 2 types of peripheral chemreceptors and identify which one plays a greater role in responding to a low PaO2
carotid and aortic bodiesCarotid bodies play a much greater role in initiating an increased ventilatory rate in response to reduced arterial oxygen levels
What are the four periods of lung development during fetal life?
embryonic, pseudoglandular, canalicular, terminal sac
What day of embryonic life does a small bud of the lungs arise from teh esophagus?
24th day
At what week gestation does the air-blood interface between the alveoli and the pulmonary capillaries and the quantity of pulmonary surfactant usually sufficient to support life?
28th week gestation
What are the 15-20 segments of the placenta called?
How is the deoxygenated blood carried from th efetus to the placenta?
two umblical arteries
What is the normal Po2 in the umblical arteries and the normal PCO2?
02 20 mm Hg and Pco2 55 mmHg
What are the reasons the maternal blood PCO2 is frequenly lower than expected during the final trimester of pregnancy?
alveolar hyperventilation due to growing infant restricting diaphragmatic excursion
What are the three factors causing oxygen transfer from teh maternal to fetal blood in the intervillous space
maternal-fetal PO2 gradienthigher hemoglobin concentration in the fetal bloodgreater affinity of fetal hemoglobin for oxygen
how does oxygenated fetal blood flow out of the chorionic villi and return to the fetus?
by way of the umbilical vein
What are three factors thought to cause wide variance between maternal and fetal Po2 and PCO2
placenta is actively metabolizing organpermeability of placenta varies from region to regionfetal and maternal vascular shunts
As oxygenated blood from the placenta returns to the fetus about half of the blood enters the liver and the rest enters inferior vena ava by flowing through what?
ductus venosus
Once in the right atrium of the fetus, most of the blood flows directly into the left atrium through what?
foramen ovale
Blood in the left atrium of the fetus enters where and is pumped where?
enters the left ventricle and is pumped to the heart and brain
most of the fetal blood that passes into the pulmonary artery from the right ventricle bypasses the lungs by passing through what and flows directly into what?
passes through the ductus arteriosas and flows directly into the aorta
How much of fetal circulation passes through the lungs and returns to the left atrium via what?
15% pulmonary veins
list structures in order in which fetal blodo passes through
ductus venosus, ductus arteriosus, common iliac arteries, external and internal iliacs, umblical arteries
What special changes occur to fetal circulation after birty
placenta passed by motherumblical arteries atrophy and become lateral umblical ligamentsumbilical vein becomes round ligament of liver (ligamentum teres)ductus venosas becomes ligamentum arteriosumflap on foramen ovale usually closes and becomes a depression in the interatrial septum called fossa ovalesductus arteriosus atrophies and becomes ligamentum arteriosum
describe what happens to fluid in fetal lungs upon birth
one third squeezed out of lungs as passes through birth canalone third absorbed by pulmonary arteriesone third removed by lymphatic system
how many million primitive alveoli are present at birth?
Until what age does the number alveoli continue to increase
until age 12
What are three stimuli that cause the infant to take the first breath
thermal, tactile, visual
How much air enters the lungs during first breath of infant
40 ml
What is the infant's intrapleural pressure decraes to before any air enters the lungs during the baby's first breath
-40 cm H2O
What is average lung compliance of the newborn?
.005 l/cm H2o
What is the average Raw of the newborn
30 cm H2O/L/sec
two mechanisms that account for decreased pulmonary vascular resisteance when infant inhales the first tiem
sudden increase in alveolar Po2 which offsets hypoxic vasoconstrictionmechanical increase in lung volume which widens the caliber of the extra alveolar vessels
describe mechanism that causes the foramen ovale to close at birth
pulmonary vascular resistence decreases a greater amount of blood flows through the lungs and therefore more blood returns to the left atrium this causes the pressure to increase in the left atrium and the flap of foramen ovale to close
At birth, the newborn's Po2 must increase to what in order for teh ductus arteriosus to close
45-50 mm Hg
PPHN is what?
(pulmonary hypertension of the neonate)when ductus arteriosas remains open, permitting blood to pass through it, and pulmonary vascular resistence is elevated, persisten pulmonary hypertension of the neonate is said to exist
PPHN stands for what and used to be called what?
persistent pulmonary hypertension of the neonateused to be called persistenat fetal circulation
3 substances released at birth said to have an effect on constriction of ductus arteriosus
bradykininserotoninprostaglandin inhibitors
What plays a role in activating the first breath at birth that is inactivated during fetal life?
peripheral and central chemoreceptors
what does stimulation of the newborns trigeminal nerve cause the infants respiration and heart rate to do?
stimulatio nof the preterm infant's irritant reflex is commonly followed by what?
respiratory slowing or apnea
stimulation of the term infant's irrtant reflex causes what?
marked hyperventilation
What is the head paradoxical reflex
deep inspiration elicited by lung inflation
What are the two types of cardiac cells
contractile muscle fibers and "pacemaker cells" called autorhythmic cells
What makes up the bulk of the musculature of the myocardium and are responsible for the pumping activity of the heart
Myocardial contractile fiber cells
approximately one percent of the heart is composed of the what type of cardiac cells?
autorhythmic cells, the majority of which are located in the SA node
autorhythmic cells, the majority of which are located in teh SA node. These cells initiate an action potential spontaneously which triggers the what to contract?
myocardial fibers
The cardiac cells have four specific properties
automaticity, excitability, conductivity and contractility
Define the term “ conductivity
conductivity is the ability of the heart cells to transmit electrical current from cell to cell throughout the entire conductive system
Sympathetic neural fibers innervate
the atria and ventricles of the heart
Sympathetic neural fibers innervate
the atria and ventricles of the heart
When stimulated, the sympathetic fibers cause what to happen to the heart rate, AV conduction, cardiac contractility and excitability
the sympathetic fibers cause an increase in the heart rate, AV conduction, cardiac contractility and excitability
Stimulation of the parasympathetic system causes what reaction in the heart rate, AV conduction, contractility and excitability
Stimulation of the parasympathetic system causes a decrease in the heart rate, AV conduction, contractility and excitability
WHat is the ECG complex that represents ventricular depolarization?
QRS complex
Three or more PVCs in a row represent what?
ventricular tachycardia
How is the QRS complex with ventricular tachycardia?
wide an bizarre making it difficult to identify the P waves and T waves
How is the rate of ventricular tachycardia?
Rate is regular or slightly irregular between 100-170 bpm
What is Ventricular tachycardia is often initiated by ?
a pvc that is significantly premature, although it may occur suddenly after a normal sinus rhythm
When ventricular tachycardia appears suddenly and then disappears moments later what is it called?
it is paroxysmal or intermittent ventricular tachycardia
the ECG tracing shows only ventriculr tachycardia, what is it called?
sustained ventricular tachycardia or V-tach
What is The blood pressure level during ventricular tachycardia
often decreased
What are the characteristics of ventricular tachycardia?
P Wave usually cannot be identifiedPR interval cannot be measuredQRS duration is usually greater than .12 second and bizarre in appearance. T wave cannot be identifiedQRS rhythm is regular or slightly irregular
Cite the functional unit of the kidneys
Nephrons are the functional unit of the kidneys
What is hydrostatic pressure in the glomerulus capillary?
hydrostatic pressure in the glomerular capillary is about 55 mm Hg
What is the hydrostatic pressure in bowman's capsule?
The hydrostatic pressure in Bowman's capsule is about 15 mm Hg
How much fluid does the glomeruli filter per minute?
The glomeruli filter about 125 mL of fluid per minute
The glomeruli filter about 125 mL of fluid per minute and of this, how much is excreted as urine?
Of this 125 mL, however, only about 1 mL is excreted as urine
What is the average urine output per day?
The average urine output is about 60 mL/hour, or 1440 mL/day
Identify the major “ion” found in the extra-cellular fluid
Sodium ions account for over 90 percent of the positively charged ions in teh extracellular fluid.
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