Lecture 19 Vascular Lung Disorders

Question 1

pulmonary artery

part of dual arterial blood supply to lungs

Answer 1

lots of blood, low pressure

supplies alveolar capillaries and distal bronchioles

Question 2

bronchial artery

part of dual arterial blood supply to lungs

Answer 2

low amount of blood, high pressure

Question 3

What happens to plasma hydrostatic pressure (and therefore net flow) as you move from arteriole to venous end of a capillary?

Answer 3

plasma hydrostatic pressure decreases
net flow out to net flow in
plasma oncotic pressure stays constant

Question 4

Prevention of pulmonary edema in health

Answer 4

alveolar cells (type 1) have tight junctions
type 2 alveolar cells have Na pumps that push Na out of alveoli (water follows)

Question 5

Dual venous drainage routes from lungs
pulmonary veins drain….
azygous veins drain….

Answer 5

the capillary beds supplied by the pulmonary artery->left heart
the capillary beds supplied by the bronchial artery->right heart

Question 6

the blood air barrier layers(4)

Answer 6

alveolar capillary endothelial cells

• alveolar interstitium
• monolayer of epithelial cells(type 1)
• surfactant containing alveolar fluid

Question 7

Which type of cell can assist with keeping alveoli dry besides type 2?

Answer 7

club cells of the distal bronchioles

Question 8

What are the adverse effects of pulmonary edema on respiratory function

Answer 8

prevents gas exchange
reduces lung compliance
macrophage function is reduced

Question 9

What are the 2 major mechanisms responsible for pulmonary edema?

Answer 9

• Inc hydrostatic pressure in alveolar capillaries

- Inc permeability of the blood alveolar barrier

Question 10

Inc hydrostatic pressure in alveolar capillaries

-where does the fluid initially accumulate and what is protein [ ]? ex of conditions that cause each

Answer 10

initial accumulation of edema fluid in the bronchovascular interstitium (especially near the hilus) (edema fluid that is low in protein)

• LSCHF (most common)
• hypervolemia
• gravitational pooling(recumbency)

Question 11

Inc permeability of the blood alveolar barrier

-where does the fluid initially accumulate and what is protein [ ]? ex of conditions that cause each

Answer 11

rapid development of pulmonary edema with direct movement of fluid from the alveolar capillaries into the alveolar lumina
edema fluid that is high in protein
*inflammation/pneumonia
*damage to capillary endothelium (renal failure)
*damage to type 1 pneumocytes(fog fever)

Question 12

What are the characteristic gross features of pulmonary edema?

Answer 12

lungs are wet, heavy, and rubbery, do not collapse when thorax is opened
moderate to severe produces stable foam(surfactant and air bubbles)

Question 13

What happens if an animal survives pulmonary edema

Answer 13

interstitial fibrosis so lungs may feel firmer

Question 14

what is the most common cause of pulmonary congestion? Characteristic gross appearance in acute and chronic

Answer 14

Passive congestion of the lungs is most often seen with LSCHF.
acute- dark red purple, heavier than normal, with edema as well
chronic- fibrosis of alveolar septa and accumulation of hemosiderin pigment by macrophages

Question 15

What causes active hyperemia of the lungs. Grossly looks like?

Answer 15

acute to subacute phase of lung injury and inflammation

• affected areas are grossly bright red
• this is the “red phase” of pneumonia

Question 16

Possible causes of hemorrhage into the lungs(4)

Answer 16

blunt chest trauma with lung contusion
penetrating injuries
hemostatic disorders
bacteremia,septicemia

Question 17

Exercise induced pulmonary hemorrhage of horses?
how common?
signs?
Where are the lung lesions located?

Answer 17

marked inc in alveolar capillary pressure->rupture of alveolar capillaries->bleeding into alveolar space and interstitium

• occurs in more than 80% of racehorses
• uncommon to see signs without doing an endoscopy- maybe epistaxis
• dorsocaudal areas

Question 18

Possible consequences of obstruction of pulmonary arterial blood flow to lungs?
typical gross appearance of an infarct in the lungs?

Answer 18

sudden obstruction ->cor pulmonale or cardiogenic shock and death

• thromboembolism
• red to black swollen firm wedges of tissue with film of fibrin

Question 19

In which animals is lung lobe torsion most commonly diagnosed? predisposing cause? consequences?

Answer 19

deep chested dog breeds
involving right middle and left cranial lobes
-predisposing causes:neoplasia, pneumonia, atelectasis
-congestion and edema->infarction

Question 20

Pulmonary hypertension

Answer 20

a sustained increase in blood pressure within the pulmonary artery

Question 21

cor pulmonale

Answer 21

characterised by right ventricular dilation or concentric hypertrophy and potentially right-sided congestive heart failure

Question 22

Causes of pulmonary hypertension

Answer 22

heartworm
congenital causes of left to right shunting
severe pulmonary arterial thrombosis

Question 23

High altitude disease in cattle

Answer 23

caused by failure of the cardiorespiratory system of cattle to adjust to hypoxia of high altitudes (> 1500 m and especially > 2500 m)
-hypoxaemia->sustained vasoconstriction of the small pulmonary arteries and arterioles-> chronic medial smooth muscle hypertrophy and increased pulmonary vascular resistance -> pulmonary hypertension->cor pulmonale