Lecture 9: Pulmonary Circ. + Breathing

Question 1

The heart drives two separate and distinct circulatory systems in the body; what are they?

Answer 1

1) Pulmonary circulation
2) Systemic circulation

Question 2

Changes in pulmonary resistances leads to changes in the ________________ ventricle

Answer 2

right

Question 3

The division of heart functions into pulmonary and systemic circuits is what kind of organization?

Answer 3

Functional organization

Question 4

What two pulmonary things branch together in parallel?

Answer 4

Pulmonary vessels and airways

Question 5

1) What comprises >40% of the lung weight?
2) What part of the body contains 10% of total circulating blood volume?

Answer 5

1) Pulmonary vessels/ airways
2) Pulmonary vessels/ airways

Question 6

True or false: pulmonary vessels and airways branch in the same treelike manner

Answer 6

True

Question 7

List 3 of the numerous secondary functions of the pulmonary vessels

Answer 7

1) Filter
2) Metabolic Organ
3) Blood reservoir

Question 8

True or false: Conducting airways have their own separate circulation

Answer 8

True

Question 9

What can undergo angiogenesis (creation of blood vessels)?

Answer 9

Conducting airways’ circulation

Question 10

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?

Answer 10

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)

Question 11

1) List 3 more common causes of PE (pulmonary embolism)
2) What do PEs cause?
3) What is the mortality rate?

Answer 11

1) Fat from marrow of a broken bone, air emboli, or a tumor fragment
2) Hypoxemia and can cause right heart strain
3) 10%

Question 12

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?

Answer 12

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)

Question 13

1) Vascular resistance is __[fraction]__ that of systemic.
2) Resistance __________ with increased cardiac output.

Answer 13

1) 1/10th
2) falls

Question 14

Fall in vascular resistance with increased CO is due to what two things involving capillaries? Define each

Answer 14

1) Capillary recruitment: Closed vessels open as pressure rises (primary reason)
2) Capillary Distention: Widening of capillary vessels

Question 15

Why does capillary recruitment occur?

Answer 15

Protective mechanism; high pressure leads to pulmonary edema

Question 16

Vascular resistance _______________ at high and low lung volumes

Answer 16

increases

Question 17

At a high lung volume, pleural pressure is more ___________

Answer 17

negative

Question 18

At a low lung volume, pleural pressure is more ___________

Answer 18

positive

Question 19

1) Low oxygen tension in the lung causes what?
2) What can this lead to?

Answer 19

1) Pulmonary vasoconstriction
2) Hypoxia-induced pulmonary vasoconstriction

Question 20

What can hypoxia-induced pulmonary vasoconstriction do to carbon dioxide and blood pH?

Answer 20

High carbon dioxide and low blood pH

Question 21

1) What occurs during regional hypoxia?
2) What does this do to pulmonary arterial pressure and resistance?

Answer 21

1) Vasoconstriction is localized to a specific region and diverts
2) Not much change in pulmonary arterial pressure/resistance

Question 22

1) What does generalized hypoxia do to pulmonary arterial resistance and pressure?
2) What is this seen more with?

Answer 22

1) Significant rise in resistance and pressure
2) Lung diseases

Question 23

1) Net fluid transfer depends on what two things?
2) What does alveolar surface tension do to filtration?

Answer 23

1) Hydrostatic and colloid osmotic pressures
2) Enhances it

Question 24

1) What does alveolar pressure do to filtration?
2) ____[Low/high]_____ pulmonary capillary hydrostatic pressure keeps the alveoli “dry”

Answer 24

1) Opposes it
2) Low

Question 25

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?

Answer 25

1) 8-10mmHG 2) Plasma colloid pressure (25mmHg) 3) The reabsorption of fluid

Question 26

1) Surface tension offsets what low pressure? 2) Why? 3) What then happens?

Answer 26

1) Pulmonary capillary hydrostatic pressure (low) 2) To flux fluid out of the capillaries into the interstitial space 3) Lymphatic channels then drain

Question 27

1) What exceeds what to cause pulmonary edema? 2) What condition can pulmonary edema cause?

Answer 27

1) Capillary filtration exceeds fluid removal 2) ARDS: Acute respiratory distress syndrome

Question 28

1) Hypoxia causes vaso-__________ in the pulmonary system 2) Chronic conditions encourage what?

Answer 28

1) vasoconstriction 2) Remodeling of arteries/arterioles

Question 29

What two things does chronic hypoxia do to arteries/ arterioles of the lungs? What do these 2 changes lead to?

Answer 29

1) Increased vascular resistance 2) Obliteration of small vessels (b/c of resistance) Hypoxia-Induced Pulmonary Hypertension

Question 30

1) What do chronic-hypoxia induced changes eventually cause? 2) What does this cause? 3) Who is this a major cause of death with?

Answer 30

1) Pulmonary edema eventually occurs 2) Right sided heart failure (from increased resistance) 3) COPD patients

Question 31

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?

Answer 31

1) Uneven distribution of blood flow 2) Blood volume & flow are greater at the bottom than the apex 3) Gravity 4) Exercise

Question 32

True or false: Regional Ventilation and Blood Flow are matched

Answer 32

False; they are not matched

Question 33

What ratio describes regional ventilation and blood flow?

Answer 33

Ventilation/Perfusion Ratio (Va/Q ratio)

Question 34

1) Ventilation is higher at the _________ 2) __________________ is higher at the base

Answer 34

1) apex 2) Perfusion

Question 35

What leads to "wasted" air and blood?

Answer 35

Mismatch of regional air and blood flow

Question 36

Define wasted air and wasted blood

Answer 36

1) Wasted Air: Physiologic Dead Space 2) Wasted Blood: venous blood that is not fully oxygenated; Venous Admixture

Question 37

What is venous admixture?

Answer 37

Wasted blood

Question 38

What are two causes of venous admixture?

Answer 38

1) Anatomic shunt 2) Low regional Va/Q ratio

Question 39

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?

Answer 39

1) Anatomic shunt 2) Ventricular septal defect (VSD) 3) Right-to-left shunt

Question 40

1) What causes a low ventilation/perfusion ratio? 2) What usually causes this?

Answer 40

1) Insufficient alveolar ventilation to fully oxygenate all the blood 2) A partially obstructed airway

Question 41

1) What are the muscles of inspiration? 2) Is inspiration conscious or subconscious? What controls it?

Answer 41

1) Diaphragm and intercostal muscles 2) The autonomic nervous system

Question 42

1) What does the medulla do for inspiration? 2) What confers conscious control of respiration?

Answer 42

1) Main control of the respiratory center; sends impulses to the phrenic nerve/intercostal nerves. 2) Limbic system/ hypothalamus

Question 43

What two things does minute ventilation depend on?

Answer 43

Metabolic demands and blood gases

Question 44

1) Increased metabolism leads to what increasing? 2) What does that lead to? 3) What does that lead to?

Answer 44

1) Levels of carbon dioxide 2) Lower pH (excess acid) 3) Respiration increases to blow off the acid

Question 45

If more ventilation is required, recruitment of what two things occurs?

Answer 45

1) Cervical muscles 2) Abdominal muscles; expiration becomes active

Question 46

What are the two groups of the medulla related to respiration? What does each stimulate and do?

Answer 46

1) Dorsal Respiratory Group -Stimulates diaphragm and intercostal muscles to contract 2) Ventral Respiratory Group -Forced breathing -Stimulates Accessory muscle use

Question 47

1) The secondary respiratory center is also called what? 2) What two things does it contain?

Answer 47

1) Pontine Respiratory Group 2) Apneustic centers and pneumotaxic centers

Question 48

1) What 2 things do apneustic centers do? 2) What do pneumotaxic centers do?

Answer 48

1) Stimulates the DRG and controls the depth on inspiration 2) Inhibitory; stops the DRG from firing allowing for relaxation

Question 49

1) What do pulmonary neural reflexes allow for? 2) What receptors mediate reflexes, and through what nerve?

Answer 49

1) Fine tuning 2) Mechanoreceptors; vagus nerve

Question 50

1) How do pulmonary neural reflexes allow for fine tuning? 2) Give 3 examples of mechanoreceptors that mediate reflexes (CNX)

Answer 50

1) Adjusts frequency and tidal volume to optimize gas exchange 2) Pulmonary stretch receptors, irritant receptors, and juxtapulmonary receptors

Question 51

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?

Answer 51

1) Within and outside the lung 2) Myelinated 3) Changes in lung volume 4) Transmural pressure; to medulla

Question 52

1) What does the Hering-Breuer Reflex stimulate? 2) What does it stop? 3) What is it protective from?

Answer 52

1) Heart rate to increase 2) Further inspiration 3) Overinflation

Question 53

1) Are pulmonary irritant receptors myelinated or unmyelinated? 2) Where are they? 3) What do they initiate?

Answer 53

1) Myelinated 2) Line the respiratory epithelium; primarily in larger conducting airways 3) Initiate coughing, gasping and breath-holding

Question 54

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?

Answer 54

1) Rapidly adapting 2) Smoke, dust and solvents 3) Histamine; can lead to severe bronchoconstriction in asthmatics

Question 55

1) What do Pulmonary J Receptors do? 2) Where are they? 3) Are they myelinated or unmyelinated?

Answer 55

1) Provide feedback about fluid volume 2) Adjacent to the alveoli and pulmonary capillaries 3) Unmyelinated

Question 56

1) What innervates Pulmonary J Receptors? 2) What activates them? (2 things) 3) What do they do when stimulated?

Answer 56

1) Vagus nerve 2) Physical engorgement of the pulmonary capillaries or increased pulmonary interstitial volume 3) They cause an increase in breathing rate

Question 57

1) What does the medulla regulate about breathing? 2) What modifies this?

Answer 57

1) Respiratory rate and depth 2) Chemoreceptors that detect changes in blood chemistry

Question 58

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?

Answer 58

1) PCO2; high concentration is toxic to cells 2) In Brain and Brainstem 3) Carotid arteries and aortic arch

Question 59

Increase in what ions will increase RR?

Answer 59

H+ ions

Question 60

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?

Answer 60

1) CO2 but not H+ nor HCO3- 2) Blood PCO2 3) Stimulate the respiratory centers in the medulla

Question 61

What are the two main types of sleep?

Answer 61

1) REM (rapid eye movement) 2) Slow-Wave sleep

Question 62

1) Describe breathing during REM sleep 2) What is the CNS response of?

Answer 62

1) Some erratic breathing but tidal volume stays the same 2) Behavioral rather than autonomic control systems

Question 63

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

Answer 63

1) Minute ventilation falls 2) PaCO2 rises (small amount) 3) True

Question 64

What are the two stimuli for breathing for wakefulness?

Answer 64

1) Changes [in] Tidal Volume 2) Cheyene-Stokes Breathing

Question 65

1) Conscious anticipation of the exercise can change what? 2) During exercise, does blood chemistry (pH) change?

Answer 65

1) Respiratory rate 2) No; cells are working more so they need the extra oxygen [being taken in]

Question 66

-The VRG and DRG stimulate what two nerves? -What 3 effects does this have?

Answer 66

-The intercostal nerve and phrenic nerve 1) Increase contraction 2) Increase ventilation 3) Increase RR and depth

Question 67

Normally, _______ of body’s energy expenditure is used for breathing

Answer 67

3%

Question 68

Work of breathing can be increased in what 4 ways?

Answer 68

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.

Question 69

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

Answer 69

25x; 5%

Question 70

In disease, energy requirements can be as ________ as ________% of total energy expenditure. Exercise capacity is severely limited.

Answer 70

high as 30%

Question 71

Decreased pulmonary compliance like pulmonary fibrosis causes what?

Answer 71

Increased work is required to expand the lungs.

Question 72

Increased airway resistance like COPD causes what?

Answer 72

Increased work is needed to establish pressure gradients.

Question 73

Decreased elastic recoil like emphysema causes what?

Answer 73

Abdominal muscles need to work to aid in emptying lungs

Question 74

When there's a need for increased ventilation like exercise, what is required?

Answer 74

More work, for increased depth and rate of breathing.