Lecture 9: Pulmonary Circ. + Breathing Flashcards
The heart drives two separate and distinct circulatory systems in the body; what are they?
1) Pulmonary circulation
2) Systemic circulation
Changes in pulmonary resistances leads to changes in the ________________ ventricle
right
The division of heart functions into pulmonary and systemic circuits is what kind of organization?
Functional organization
What two pulmonary things branch together in parallel?
Pulmonary vessels and airways
1) What comprises >40% of the lung weight?
2) What part of the body contains 10% of total circulating blood volume?
1) Pulmonary vessels/ airways
2) Pulmonary vessels/ airways
True or false: pulmonary vessels and airways branch in the same treelike manner
True
List 3 of the numerous secondary functions of the pulmonary vessels
1) Filter
2) Metabolic Organ
3) Blood reservoir
True or false: Conducting airways have their own separate circulation
True
What can undergo angiogenesis (creation of blood vessels)?
Conducting airways’ circulation
1) Define pulmonary embolism (PE)
2) What does it create? (2 things)
3) What does this then cause?
4) What is the most common cause of PEs?
1) Sudden blockage in a lung artery that impedes blood flow
2) Increased ventilation/perfusion ratio and physiologic dead space
3) Hypoxemia; can cause right heart strain; 10% die
4) Deep vein thrombosis (DVT)
1) List 3 more common causes of PE (pulmonary embolism)
2) What do PEs cause?
3) What is the mortality rate?
1) Fat from marrow of a broken bone, air emboli, or a tumor fragment
2) Hypoxemia and can cause right heart strain
3) 10%
1) Describe the flow, pressure, and resistance of pulmonary circulation
2) What does it not contain as much of [comp. to systemic circ.]?
3) Pulmonary capillaries set up as what?
1) High-Flow, Low-Pressure, Low-Resistance System
2) Contain less smooth muscle than systemic circulation
3) A dense capillary bed (as opposed to the straight lines in systemic)
1) Vascular resistance is __[fraction]__ that of systemic.
2) Resistance __________ with increased cardiac output.
1) 1/10th
2) falls
Fall in vascular resistance with increased CO is due to what two things involving capillaries? Define each
1) Capillary recruitment: Closed vessels open as pressure rises (primary reason)
2) Capillary Distention: Widening of capillary vessels
Why does capillary recruitment occur?
Protective mechanism; high pressure leads to pulmonary edema
Vascular resistance _______________ at high and low lung volumes
increases
At a high lung volume, pleural pressure is more ___________
negative
At a low lung volume, pleural pressure is more ___________
positive
1) Low oxygen tension in the lung causes what?
2) What can this lead to?
1) Pulmonary vasoconstriction
2) Hypoxia-induced pulmonary vasoconstriction
What can hypoxia-induced pulmonary vasoconstriction do to carbon dioxide and blood pH?
High carbon dioxide and low blood pH
1) What occurs during regional hypoxia?
2) What does this do to pulmonary arterial pressure and resistance?
1) Vasoconstriction is localized to a specific region and diverts
2) Not much change in pulmonary arterial pressure/resistance
1) What does generalized hypoxia do to pulmonary arterial resistance and pressure?
2) What is this seen more with?
1) Significant rise in resistance and pressure
2) Lung diseases
1) Net fluid transfer depends on what two things?
2) What does alveolar surface tension do to filtration?
1) Hydrostatic and colloid osmotic pressures
2) Enhances it
1) What does alveolar pressure do to filtration?
2) ____[Low/high]_____ pulmonary capillary hydrostatic pressure keeps the alveoli “dry”
1) Opposes it
2) Low
1) Mean pulmonary capillary hydrostatic pressure is normally what? (Don’t rlly need to know)
2) What is this lower than?
3) What does this favor?
1) 8-10mmHG
2) Plasma colloid pressure (25mmHg)
3) The reabsorption of fluid
1) Surface tension offsets what low pressure?
2) Why?
3) What then happens?
1) Pulmonary capillary hydrostatic pressure (low)
2) To flux fluid out of the capillaries into the interstitial space
3) Lymphatic channels then drain
1) What exceeds what to cause pulmonary edema?
2) What condition can pulmonary edema cause?
1) Capillary filtration exceeds fluid removal
2) ARDS: Acute respiratory distress syndrome
1) Hypoxia causes vaso-__________ in the pulmonary system
2) Chronic conditions encourage what?
1) vasoconstriction
2) Remodeling of arteries/arterioles
What two things does chronic hypoxia do to arteries/ arterioles of the lungs?
What do these 2 changes lead to?
1) Increased vascular resistance
2) Obliteration of small vessels (b/c of resistance)
Hypoxia-Induced Pulmonary Hypertension
1) What do chronic-hypoxia induced changes eventually cause?
2) What does this cause?
3) Who is this a major cause of death with?
1) Pulmonary edema eventually occurs
2) Right sided heart failure (from increased resistance)
3) COPD patients
1) Is there an even distribution flow of blood in the lungs?
2) Explain.
3) Why is this the case?
4) What can offset this?
1) Uneven distribution of blood flow
2) Blood volume & flow are greater at the bottom than the apex
3) Gravity
4) Exercise
True or false: Regional Ventilation and Blood Flow are matched
False; they are not matched
What ratio describes regional ventilation and blood flow?
Ventilation/Perfusion Ratio
(Va/Q ratio)
1) Ventilation is higher at the _________
2) __________________ is higher at the base
1) apex
2) Perfusion
What leads to “wasted” air and blood?
Mismatch of regional air and blood flow
Define wasted air and wasted blood
1) Wasted Air: Physiologic Dead Space
2) Wasted Blood: venous blood that is not fully oxygenated; Venous Admixture
What is venous admixture?
Wasted blood
What are two causes of venous admixture?
1) Anatomic shunt
2) Low regional Va/Q ratio
1) What is it called when blood bypasses alveoli through a channel?
2) Give an example
3) Is it often left to right, or right to left?
1) Anatomic shunt
2) Ventricular septal defect (VSD)
3) Right-to-left shunt
1) What causes a low ventilation/perfusion ratio?
2) What usually causes this?
1) Insufficient alveolar ventilation to fully oxygenate all the blood
2) A partially obstructed airway
1) What are the muscles of inspiration?
2) Is inspiration conscious or subconscious? What controls it?
1) Diaphragm and intercostal muscles
2) The autonomic nervous system
1) What does the medulla do for inspiration?
2) What confers conscious control of respiration?
1) Main control of the respiratory center; sends impulses to the phrenic nerve/intercostal nerves.
2) Limbic system/ hypothalamus
What two things does minute ventilation depend on?
Metabolic demands and blood gases
1) Increased metabolism leads to what increasing?
2) What does that lead to?
3) What does that lead to?
1) Levels of carbon dioxide
2) Lower pH (excess acid)
3) Respiration increases to blow off the acid
If more ventilation is required, recruitment of what two things occurs?
1) Cervical muscles
2) Abdominal muscles; expiration becomes active
What are the two groups of the medulla related to respiration? What does each stimulate and do?
1) Dorsal Respiratory Group
-Stimulates diaphragm and intercostal muscles to contract
2) Ventral Respiratory Group
-Forced breathing
-Stimulates Accessory muscle use
1) The secondary respiratory center is also called what?
2) What two things does it contain?
1) Pontine Respiratory Group
2) Apneustic centers and pneumotaxic centers
1) What 2 things do apneustic centers do?
2) What do pneumotaxic centers do?
1) Stimulates the DRG and controls the depth on inspiration
2) Inhibitory; stops the DRG from firing allowing for relaxation
1) What do pulmonary neural reflexes allow for?
2) What receptors mediate reflexes, and through what nerve?
1) Fine tuning
2) Mechanoreceptors; vagus nerve
1) How do pulmonary neural reflexes allow for fine tuning?
2) Give 3 examples of mechanoreceptors that mediate reflexes (CNX)
1) Adjusts frequency and tidal volume to optimize gas exchange
2) Pulmonary stretch receptors, irritant receptors, and juxtapulmonary receptors
1) Where are pulmonary stretch receptors located?
2) Are they myelinated or unmyelinated?
3) What do they detect?
4) What do they fire in response to? Where does this signal go?
1) Within and outside the lung
2) Myelinated
3) Changes in lung volume
4) Transmural pressure; to medulla
1) What does the Hering-Breuer Reflex stimulate?
2) What does it stop?
3) What is it protective from?
1) Heart rate to increase
2) Further inspiration
3) Overinflation
1) Are pulmonary irritant receptors myelinated or unmyelinated?
2) Where are they?
3) What do they initiate?
1) Myelinated
2) Line the respiratory epithelium; primarily in larger conducting airways
3) Initiate coughing, gasping and breath-holding
1) Describe adaptation of pulmonary irritant receptors
2) What do irritant receptors respond to?
3) What NT can stimulate them? What can this lead to?
1) Rapidly adapting
2) Smoke, dust and solvents
3) Histamine; can lead to severe bronchoconstriction in asthmatics
1) What do Pulmonary J Receptors do?
2) Where are they?
3) Are they myelinated or unmyelinated?
1) Provide feedback about fluid volume
2) Adjacent to the alveoli and pulmonary capillaries
3) Unmyelinated
1) What innervates Pulmonary J Receptors?
2) What activates them? (2 things)
3) What do they do when stimulated?
1) Vagus nerve
2) Physical engorgement of the pulmonary capillaries or increased pulmonary interstitial volume
3) They cause an increase in breathing rate
1) What does the medulla regulate about breathing?
2) What modifies this?
1) Respiratory rate and depth
2) Chemoreceptors that detect changes in blood chemistry
1) What is a major factor in medullary control of respiratory rate and depth? Why?
2) Where are the central chemoreceptors?
3) Where are the peripheral chemoreceptors?
1) PCO2; high concentration is toxic to cells
2) In Brain and Brainstem
3) Carotid arteries and aortic arch
Increase in what ions will increase RR?
H+ ions
1) Blood-Brain Barrier is permeable to __________ but not __________ nor _________
2) What can influence the pH of CSF?
3) What can pH of CSF do?
1) CO2 but not H+ nor HCO3-
2) Blood PCO2
3) Stimulate the respiratory centers in the medulla
What are the two main types of sleep?
1) REM (rapid eye movement)
2) Slow-Wave sleep
1) Describe breathing during REM sleep
2) What is the CNS response of?
1) Some erratic breathing but tidal volume stays the same
2) Behavioral rather than autonomic control systems
1) What about breathing falls during slow wave sleep?
2) What rises during slow wave sleep?
3) True or false: Stimulus for breathing varies for wakefulness
1) Minute ventilation falls
2) PaCO2 rises (small amount)
3) True
What are the two stimuli for breathing for wakefulness?
1) Changes [in] Tidal Volume
2) Cheyene-Stokes Breathing
1) Conscious anticipation of the exercise can change what?
2) During exercise, does blood chemistry (pH) change?
1) Respiratory rate
2) No; cells are working more so they need the extra oxygen [being taken in]
-The VRG and DRG stimulate what two nerves?
-What 3 effects does this have?
-The intercostal nerve and phrenic nerve
1) Increase contraction
2) Increase ventilation
3) Increase RR and depth
Normally, _______ of body’s energy expenditure is used for breathing
3%
Work of breathing can be increased in what 4 ways?
1) Decreased pulmonary compliance like pulmonary fibrosis. Increased work required to expand the lungs.
2) Increased airway resistance like COPD. Increased work needed to establish pressure gradients.
3) Decreased elastic recoil like emphysema. Abdominal muscles need to work to aid in emptying lungs.
4) Need for increased ventilation like exercise. More work required for increased depth and rate of breathing.
In exercise, breathing energy can increase up to ______x but so does body’s total energy expenditure so work of breathing remains about _____% of total expenditure
25x; 5%
In disease, energy requirements can be as ________ as ________% of total energy expenditure. Exercise capacity is severely limited.
high as 30%
Decreased pulmonary compliance like pulmonary fibrosis causes what?
Increased work is required to expand the lungs.
Increased airway resistance like COPD causes what?
Increased work is needed to establish pressure gradients.
Decreased elastic recoil like emphysema causes what?
Abdominal muscles need to work to aid in emptying lungs
When there’s a need for increased ventilation like exercise, what is required?
More work, for increased depth and rate of breathing.
