340 chapter 10

Breathing mechanics

-Inspiration: volume of lung increases -Expiration: volume of lung decreases Ventilation (movement of air) occurs because of bulk flow. Pressure differences between intrapulmonary pressure and atmospheric pressure

Match the following -It is the movement of respiratory gases (via diffusion) from the blood into the cells of the body -It is the movement of respiratory gases between the gas exchange region of the lung and the blood

-It is the movement of respiratory gases (via diffusion) from the blood into the cells of the body= Systemic gas exchange -It is the movement of respiratory gases between the gas exchange region of the lung and the blood= Alveolar gas exchange

Match the following -It refers to the mechanical process of moving air into and out of the lungs -It is the random movement of molecules from an area of high concentration to an area of lower concentration

-It refers to the mechanical process of moving air into and out of the lungs= Ventilation -It is the random movement of molecules from an area of high concentration to an area of lower concentration= Diffusion

Does the pulmonary system limit exercise performance?

-Low-to-moderate intensity exercise= pulmonary system does not limit exercise tolerance -High intensity exercise= pulmonary ventilation/gas exchange is NOT a limitation in healthy individuals at sea level. Respiratory muscle fatigue does occur during high intensity exercise and can limit ventilatory capacity during prolonged high intensity exercise -Gas exchange DOES limit exercise in SOME elite endurance athletes. 40-50% experience hypoxemia (V/Q mismatch; and/or short RBC transit time due to high cardiac output)

purpose of respiratory system

-Pulmonary respiration: ventilation, exchange of O2 and CO2 in the lungs (balances acid-base system) -Cellular respiration: O2 utilization and CO@ production by the tissues

Ventilation and Acid-Base Balance:

-Pulmonary ventilation removes H+ from blood by the HCO3- reaction -increased ventilation results in CO2 exhalation (reduced PCO2 and H+ concentration (pH increase)) -decreased ventilation results in buildup of CO2 (increases PCO2 and H+ concentration (pH decrease))

Match the components of the respiratory control center with their descriptions. -The primary neural pacemaker responsible for inspiration -Controls active expiration

-The primary neural pacemaker responsible for inspiration= The preBotzinger complex (preBotC) -Controls active expiration= The retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG)

According to Fick's law of diffusion, why is the lung is an ideal organ for gas exchange? (Check all that apply.) -The driving pressure between the two sides of the lung tissue is low. -The total surface area available in the lung for diffusion is large. -The pleura of the lung is extremely thick. -The alveolar membrane in the lung is extremely thin.

-The total surface area available in the lung for diffusion is large. -The alveolar membrane in the lung is extremely thin.

Match the types of humoral chemoreceptor with their descriptions -These are located in the medulla and are affected by changes in PCO2 and H+ of the cerebrospinal fluid -They are located in the aortic arch and at the bifurcation of the common carotid artery. They respond to changes in arterial H+ concentrations, PCO2, blood potassium levels, and arterial PO2

-These are located in the medulla and are affected by changes in PCO2 and H+ of the cerebrospinal fluid= Central chemoreceptors -They are located in the aortic arch and at the bifurcation of the common carotid artery. They respond to changes in arterial H+ concentrations, PCO2, blood potassium levels, and arterial PO2= Peripheral chemoreceptors

Ventilation/blood flow relationships (ventilation/perfusion ratio?. Figure represents the resting state

-Under-perfused (poor gas exchange) -Average is .8 at rest -over-perfused (perfusion is higher than the ventilation)

Neural input to respiratory control center

-central chemoreceptors: located in the medulla oblongata, increases PCO2 -Carotid body (peripheral chemoreceptor), increases PCO2, decreases pH and PO2. Sensitive to changes in arterial PO2, PCOs, and pH. -Aortic body (peripheral), increases PCO2 and decreases pH muscle mechanoreceptors increases muscle contractile activity -muscle chemoreceptors decrease pH and K+ -lung stretch receptors: stretch of the bronchi

what happens to pressure when you're breathing? *

-end of expiration (not breathing)= pressure is equal -inspiration= increase in volume= decrease in alveolar pressure than atmospheric pressure -end of inspiration= pressure is equal -expiration= volume decreases= increase in alveolar pressure than atmospheric pressure so air flows out of the

Changes in Ventilation, Blood Gases, and pH during Graded Exercise

-linear increase in VE up about 50-75% VO2 followed by exponential increase in VE (ventilatory threshold) -note the differences in arterial PO2 between untrained individual vs elite trained distance runner -possible causes of exercise-induced hypoxemia due: 1) V/Q mismatch; and/or short RBC transit time due to high cardiac output (moving so fast you can't saturate blood)

Changes in breathing patterns during exercise

-tidal volume increases until heavy exercise

Oxyhemoglobin dissociation curve Deoxyhemoglobin + O2 ⇔ oxygemoglobin ***

Direction of reaction depends on: -PO2 of the blood -Affinity between Hb and O2 At the lung: high PO2= formation of oxyhemoglobin At the tissues: low PO2=release of O2 to tissues

Effect of pH and Temperature on Shape of Oxygen-hemoglobin dissociation curve

If pH is lower, at the same PO2, you have lower oxygen saturation (dumping more O2). Same with temperature when goes to left, hemoglobin holds on to oxygen more and doesn't get to tissues. Shift to the right is normal response

locations of the brain stem respiratory control centers

Inspiration -respiratory control center is located in the medulla oblongata -preBotzinger complex (PreBotC) -Pontine respiratory center Expiration -Retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG) -both humoral chemoreceptors and neural sources

Ventilatory control during exercise

Submaximal exercise -Primary drive: Higher brain centers (central command) -Fine tuned by: Humoral chemoreceptors, Neural feedback from muscle Heavy exercise Alinear rise in VE -Increasing blood H+ (from lactic acid) stimulates carotid bodies -Increases in K+, body temperature, and blood catecholamines may stimulate breathing

Diffusion of gases Fick's law of diffusion=

The rate of gas transfer (V gas) is proportional to the tissue area, the diffusion coefficient of the gas, and the difference in the partial pressure of the gas on the two sides of the tissue, and inversely proportional to the thickness

True or false: When blood flow to the alveolus does not adequately match ventilation, gas exchange occurs rapidly.

This is false. If blood flow to the alveolus does not adequately match ventilation, gas exchange does not occur.

Identify a structure in the conducting zone of the human respiratory system.

Trachea

Although there is an increase in ventilation during prolonged submaximal exercise in a hot or humid environment, there is little change in PCO2. This suggests that the increase in ventilation is due to an increase in _____.

breathing frequency and dead-space ventilation

The major muscle of inspiration, which causes an increase in the volume of the chest, is the _____.

diaphragm

muscles of respiration when exercising

diaphragm still the most important but other muscles are used when exercising too, know muscles**

True or false: Arterial PO2 decreases and arterial PCO2 tends to increase slightly in the transition from rest to steady-state exercise. This observation suggests that the increase in metabolism at the beginning of exercise is not as rapid as the increase in alveolar ventilation.

false This is false. Arterial PO2 decreases and arterial PCO2 tends to increase slightly in the transition from rest to steady-state exercise. This observation suggests that the increase in alveolar ventilation at the beginning of exercise is not as rapid as the increase in metabolism.

True or false: Similar to the muscular-skeletal system and the cardiovascular system, the lungs also undergo adaptive changes in response to regular endurance exercise.

false This is false. Endurance exercise training has no measurable effect on lung structure and pulmonary function.

The conducting zone of the respiratory system not only serves as a passageway for air, but also functions to _____.

filter, warm, and humidify the air

During inspiration, when the diaphragm contracts, it _____.

forces the abdominal contents downward and forward

At the beginning of constant-load submaximal exercise, there is an initial rapid _____.

increase in ventilation

At a constant pH, the affinity of hemoglobin for O2 is _____.

inversely related to blood temperature

When compared to the systemic circuit, the pulmonary circuit has a _____.

lower pressure

Oxygen transport in muscle is carried out by the oxygen-binding protein called _____.

myoglobin

Input to the respiratory control center can be classified into _____.

neural and humoral

The "initial" drive to increase ventilation during exercise is due to _____.

neural input from higher brain centers

What is pulmonary ventilation and the equation subscripts

pulmonary ventilation = the movement of gas into and out of the lungs V=volume of gas. Dot over V means per minute. Subscripts T,D,A,I,E are used to denote: -Tital volume (T) -Dead space (D) -Alveolar (A) -Inspired (I) -Expired (E)

During active expiration, the muscles in the abdominal wall work to _____.

push the diaphragm upward

The pulmonary circuit and the systemic circuit of blood flow are similar in that both circuits have equal _____.

rates of blood flow

In the context of the effect of 2-3 DPG (2-3 diphosphoglycerate) on the oxygen-hemoglobin dissociation curve, the compound 2-3 DPG combines with hemoglobin and _____.

reduces hemoglobin's affinity for O2

The adaptability of pulmonary structures to endurance training is substantially less than the muscular-skeletal system and the cardiovascular system because the _____.

structural capacity of the normal lung is overbuilt

Blood flow within the lung is uniform when an individual is in the _____ position.

supine

Identify a technique used to measure pulmonary volumes in which a subject is required to breathe into a device that is capable of measuring inspired and expired gas volumes.

Spirometry

what is used to measure lung volumes

spirometry

The amount of gas ventilated per minute is the product of the frequency of breathing and the _____.

tidal volume

Endurance training does not change lung structure

training does not alter lung structure -normal lung exceeds demand for gas exchange. Therefore, training-induced adaptation is not required for the lung to maintain blood-has homeostasis during exercise

True or false: The ventilatory threshold (Tvent) occurs in both trained athletes and untrained students.

true

Exercise-induced hypoxemia in elite athletes is likely to occur because of _____

ventilation-perfusion mismatch and diffusion limitations

During an incremental exercise test, ventilation increases as a linear function of oxygen uptake up to 50% to 70% of O2 max, where ventilation begins to rise exponentially. This VE "inflection point" has been called the _____.

ventilatory threshold

Total lung capacity is the sum of _____.

vital capacity and residual volume

In the context of exercise and the oxygen transport in blood, the strength of the bond between O2 and hemoglobin is _____.

weakened by a decrease in blood pH

In the context of the oxygen transport in blood, the strength of the bond between O2 and hemoglobin is _____. -weakened by a decrease in blood pH -increased by a decrease in blood pH -increased by an increase in blood temperature -weakened by a decrease in blood temperature

weakened by a decrease in blood pH

during rest, what does the diaphragm do

with inspire, diaphragm goes down and out of the body to increase area of lungs to expand

Organization of the Respiratory System

Upper respiratory system - above the larynx Lower respiratory system - below the larynx -respiratory zone is at the alveoli gas exchange

pulmonary ventilation equation

V= VT x F -VT= volume of gas moved per breath F= frequency of breathing

Changes in ventilation and blood gases during prolonged exercise/hot environment

VE drifts upward due to increased body temp -arterial PCO2 remains constant; how is this possible with increase in VE?

impact of endurance exercise training on ventilation during exercise

Ventilation is lower during exercise following endurance training. -Exercise ventilation is 20-30% lower at same submaximal work rate Mechanism: changes in aerobic capacity of locomotor muscles. Results in less production of H+, less afferent feedback from muscle to stimulate breathing

ventilation-perfusion relationships

Ventilation/perfusion ratio (V/Q) -Indicates matching of blood flow to ventilation -Ideal: 1.0 (or above if blood flow is high) Apex of lung (standing at rest) -Underperfused (V/Q ratio >1.0)

The volume of inspired gas that reaches the respiratory zone is referred to as _____.

alveolar ventilation

The human respiratory system is composed of a group of passages that filter air and transport it into the lungs, where gas exchange occurs within tiny air sacs called _____.

alveoli

Moderate exercise results in _____. -disproportionately high ventilation relative to blood flow -an increase in V/Q inequality -greater blood flow relative to ventilation -an improvement in the V/Q relationship

an improvement in the V/Q relationship

A majority of the CO2, which is about 70%, in the blood is transported in the form of _____.

bicarbonate

During prolonged submaximal exercise in a hot or humid environment, ventilation tends to drift upward due to an increase in _____.

blood temperature

The _____ are responsible for the increase in VE following exposure to low PO2.

carotid bodies

CO2 diffusion in cells and blood Chloride shift and the reverse process

chloride shift is what brings it out on red blood cell. Turns back into CO2 and goes into alveoli

In the context of the effect of 2-3 DPG (2-3 diphosphoglycerate) on the oxygen-hemoglobin dissociation curve, red blood cell concentrations of 2-3 DPG increase _____.

during exposure to altitude

A secondary factor that might contribute to ventilatory control during heavy exercise is a(n) _____. -increase in blood potassium levels -decrease in blood calcium levels -increase in blood calcium levels -decrease in blood potassium levels

increase in blood potassium levels

The rise in blood lactate that occurs during incremental exercise may be the cause of the alinear rise in the ventilatory threshold, because the carotid bodies that increase the threshold can be stimulated by a(n) _____. -decrease in body temperature -decrease in blood catecholamines -increase in hydrogen ion levels -increase in calcium

increase in hydrogen ion levels

Blood flow within the lung is higher at the apex of the lung than the base of the lung when an individual _____.

is suspended upside down

Overview of Respiration

know what pathways and structures include and what they do

Regional blood flow in lung

less when you get to top of ribs/lungs

In the context of the oxygen-hemoglobin dissociation curve, the combination of O2 with hemoglobin in the lung (alveolar capillaries) is often called _____.

loading

Motor neuron activity, is directly controlled by the respiratory control center in the _____.

medulla oblongata

Input for the regulation of ventilation can come in the form of efferent input from the _____.

motor cortex The motor cortex is part of the higher brain centers which is where efferent signaling would originate from.

Partial Pressure of O2 and CO2

oxygen is highest externally

Both the right and the left lungs are enclosed by a set of membranes called _____.

pleura

Besides responding to high PCO2, Carotid bodies also promote increase in ventilation as a response to increases in blood levels of _____.

potassium

The primary purpose of the respiratory system is to _____.

provide a means of gas exchange between the external environment and the body

Input for the regulation of ventilation can come in the form of afferent pathways from mechanoreceptors in the _____ of the heart relative to increases in cardiac output.

right ventricle

Contraction and relaxation of the respiratory muscles are directly controlled by _____.

somatic motor neurons in the spinal cord

Match the terms used to describe pulmonary capacities with their descriptions. -It is the volume of gas remaining in the lungs after a maximum expiration -It is the maximum amount of gas that can be expired after a maximum inspiration -It is the volume of gas in the lungs after a maximum inspiration

-It is the volume of gas remaining in the lungs after a maximum expiration= Residual volume -It is the maximum amount of gas that can be expired after a maximum inspiration= Vital capacity -It is the volume of gas in the lungs after a maximum inspiration= Total lung capacity

What is the tidal volume at rest? (VT)

500 ml (amount of air inhaled or exhaled in one breath during quiet breathing)

O2 transport in blood

99% of O2 is transported bound to hemoglobin (Hb) -Oxyhemohlobin = Hb bound to O2 -Deoxyhemoglobin = Hb not bound to O2

Spirogram illustrating diagnosis of airway obstruction

COPD: FEV1= 1 L, VC= 3 L, FEV1/VC = 33% Normal: FEV1/VC= 80% VC= vital capacity

Position of Lungs/Pleural Pressure

Lungs are enclosed by membranes called pleura -Visceral pleura= on outer surface of lung -Parietal pleura=lines the thoracic walls -Intrapleural space= intrapleural pressure in lower than atmospheric, prevents collapse of alveoli -diaphragm is the major muscle of inspiration

pulmonary ventilation airflow equation

Airflow= P1-P2 / Resistance Alveolar ventilation can be computed as: VA = VT - VD

Identify a structure that is a part of the respiratory zone of the respiratory system.

Alveolar sacs

Bulk flow is the movement of molecules along a passageway due to _____.

a pressure difference between the ends of the passageway

During exercise, increased heat production in the contracting muscle would promote _____.

a right shift in the oxyhemoglobin dissociation curve

The ideal ventilation-to-perfusion ratio (V/Q) is _____ or slightly greater.

1.0

Oxygen-hemoglobin dissociation curve

100% is at arteries 40-100 mm Hg PO2 at 40, oxygen unloads and goes in veins -Amount of O2 unloaded to tissues is 5 mmHg when you shift it to the left, the partial pressure and percentage is going down (dumping O2). to the right=saturating blood

ventilation-perfusion relationships pt 2

Base of lung (standing rest) -Overperfused (ratio <1.0) -More blood supply than at the apex During exercise -Light exercise improves V/Q ratio (TOWARD 1 OR SLIGHTLY GREATER, WHICH IS IDEAL) -Heavy exercise results in V/Q inequality and impair performance

A decrease in blood pH results in a right shift in the oxyhemoglobin curve and is called the _____.

Bohr effect

spirogram showing lung volumes at rest after you take a normal breath in and inspire as much as you can, what would it be

Tidal volume is 500 ml of just breathing and sitting -deep breath in is the inspiratory capacity (IC) -reserve volumes are after tidal volumes Answer= inspiratory capacity

Part of each breath remains in conducting airways and thus does not participate in gas exchange. This unused ventilation is called _____.

dead-space ventilation

changes in ventilation as a function of arterial PO2

decreases exponentially with a hypoxic threshold Oppositely, Effect of increases in arterial PCO2 on ventilation increases linearly

The most important variable contributing to airway resistance is the _____.

diameter of the airway

Myoglobin is capable of discharging its O2 at very low PO2 values, because it has a _____.

greater affinity for O2 than hemoglobin

Growing evidence suggests that the pulmonary system may limit exercise performance during _____ exercise at sea level.

high-intensity

Fine-tuning of breathing to match the metabolic rate is performed by input from _____.

humoral chemoreceptors

At rest, the process of expiration _____.

requires no muscular effort

Research confirms that during high-intensity exercise, _____.

respiratory muscle fatigue does occur

The total pressure of a gas mixture is equal to the sum of the pressures that each gas would exert independently. This law of partial pressure is referred to as _____.

Dalton's law

what is diffusion and ventilation

-Diffusion= movement of molecules from an area of high concentration to an area of lower concentration -Ventilation= mechanical process of moving air into and out of lungs

purpose of respiratory system during exercise

-Gas exchange between the environment and the body -Regulation of acid-base balance during exercise Other terms: -Diffusion= movement of molecules from an area of high concentration to an area of lower concentration -Ventilation= mechanical process of moving air into and out of lungs

Effect of increases in arterial PCO2 on ventilation

(left graph) it is increases linearly

Partial pressures in the body

- PO2 in lung > Po2 in blood. (why O2 goes from lungs to blood) - PCO2 in lung < PCO2 in blood. (why CO2 goes from blood to lungs to be oxygenated) - PO2 in blood > PO2 in tissues (why O2 goes to tissues like muscles for movement) - PCO2 in blood < PCO2 in tissues (CO2 is removed from tissues to go to blood to go to lungs)

Conducting and Respiratory zones of pulmonary system

-Conducting zone conducts air to respiratory zone. Humidifies, warms and filters air. (Trachea, bronchi, bronchioles, terminal bronchioles) -respiratory zone: exchange of gases between air and blood. Alveolar sacs -surfactant prevents alveolar collapse (respiratory bronchioles, alveolar ducts, alveolar sacs)

Which of the following processes occur during the exchange of O2 and CO2 between the lung and blood? (Check all that apply.)

Advection Radiation

what happens to airflow when resistance is increased?

Airflow is decreased Pressure increases = airflow increases

O2 transport in blood pt 2

Amount of O2 that can be transported per unit volume of blood is dependent on the Hb concentration -each gram of Hb can transport 1.34 ml O2 -oxygen content of blood (100% Hb saturation) -Males: 150g Hb/L bloodX1.34 ml O2 per g Hb = 200 ml per L blood -Females: 130g Hb/L bloodX1.34 ml O2 per g Hb = 174 ml per L blood

Gas exchange across alveolar wall into capillaries -how?

Bronchial tree connects the trachea to the alveoli -only one membrane of alveoli and one membrane of capillaries for O2 and CO2 to cross through (2 membrane layers). Pressure goes from high to low (like from blood O2 goes into tissues)

CO2 transport in blood know equation

CO2 transported in blood in three ways: -Dissolved in plasma (10%) -Bound to Hb (20%) -bicarbonate (70%) ** biggest enzyme carbonic anhydrase transforms CO2 and water into carbonic acid, which then dissociates in to hydrogen and bicarbonate (HCO3-)

Partial pressure of gases Dalton's Law=

Dalton's Law= the total pressure of a gas mixture is equal to the sum of the pressure that each gas would exert independently -calculation of partial pressure: P(air) = PO2+PCO2+PN2 (PN2= partial pressure of nitrogen)

True or false: In the context of the oxygen-hemoglobin dissociation curve, loading and unloading are irreversible reactions.

False This is false. The combination of O2 with hemoglobin in the lung (alveolar capillaries) is often called loading, and the release of O2 from hemoglobin at the tissues is commonly called unloading. Loading and unloading are reversible reactions.

The rate of gas transfer is proportional to the tissue area, the diffusion coefficient of the gas, and the difference in the partial pressure of the gas on the two sides of the tissue, and is inversely proportional to the thickness. This is known as _____.

Fick's law of diffusion

Comparison of myoglobin and hemoglobin dissociation curve

Mb has a higher affinity for O2 than hemoglobin -Mb has stronger partial pressure

Myoglobin serves as an O2 binding protein in skeletal muscle Myoglobin (Mb) = shuttles O2 from the cell membrane to the mitochondria

Mb has a higher affinity for O2 than hemoglobin -binds O2 at a very low PO2 -allows Mb to store O2 --O2 reserve for muscle --buffers muscle O2 needs at onset of exercise until cardiopulmonary system increases O2 delivery to muscle

blood flow to the lung -gravity is most important

Pulmonary circuit: -same rate of flow as systemic circuit -lower pressure ***During resting condition (standing), most of the blood flow is to the base of the lung due to gravitational force -During exercise, blood flow increases in top of lung (apex)***

Diffusion limitations during intense exercise in elite athletes could occur due to a reduced amount of time that _____ spend in the pulmonary capillary.

RBCs

Airflow through the pulmonary system is increased anytime there is a decrease in _____. -airway resistance -vascular resistance -the pressure gradient -the airway pressure

airway resistance

Changes in ventilation and arterial gases during transition from rest to moderate intensity exercise

When ventilation starts, PO2 goes down at first, PCO2 goes up a little, but both are relatively unchanged - VE increases rapidly, -all maintains steady stage after a couple min

Heavy exercise results in _____.

a small V/Q inequality

The pressure that each gas exerts independently can be calculated by multiplying the fractional composition of the gas by the _____.

absolute pressure

The function of the respiratory zone is to _____.

act as the site of gas exchange between the alveoli and blood

Neural input to the respiratory control center refers to _____ input.

afferent or efferent