L3: Respiratory Component

what is the difference between the thoracic cavity and thoracic cage?

-thoracic cage is just the skeleton

consider: stomach

• within the rib cage (thoracic cage) but in abdominal cavity, not thoracic

what should you note about the pleura?

-small amounts of serous fluid

which cells of the pleura are simple squamous?

-mesothelial cells (1 cell thick)

what is the biggest fx of the pleura?

lubrication

when are the pleural sacs important?

-embryologically - the pleura sacs line thoracic cavity and lungs grow into them

which pleural sac is larger?

R (more lung tissue on R side (consider: more lobes)

space between pleura sacs?

-mediastinum

-where the pleural sacs push against each other

space inside pleural sac?

-pleural cavity

what is found in mediastinum?

-bascially everything, in thoracic cavity, except lungs

-trachea

-esophagus

-heart

-vessels

which part of the respiratory system forms first?

-trachea

explanation:

lungs and pleura while forming

-as lungs push into pleural space already covered in pulmonary viseral pleura

- pulmonary visceral pleura then forms up against the parietal pleura

-space between pulmonary visceral pleura and parietal pleura is called pleura space

-small amounts of serous fluid in pleural space

Location:

Coastal pleura

-against ribs (inside rib cage) location

location:

Diaphragmatic pleura

– Against diaphragm

Location:

Mediastinal pleura

– Against mediastinum

(3) types of parietal pleura

-costal

-diaphragmatic

-mediastinal

What is pleural exudate?

-too much pleural fluid

Why is plural space fluid so important? (Lungs)

– Lungs do not have muscles, only mm thorax

– Fluid allows for a vacuum; lungs to stick to the thoracic cavity so as that increases bigger, the lungs move with it and expand

What is important to note about the surface tension of the plural space and lungs?

– Is what causes the lungs to stick to the thoracic cavity

– based on the tension of pleural fluid

– Note: not suction because there is no change in pressure

-as the lungs and thorax expand allows for the lungs and thorax to rub against each other and not cause irritation and information

Why is the plural space so important for lung and thorax movement

– There is no physical (like membronous) connection between the lungs and the thorax; need the serous fluid

How are the mediastinum parts described?

– Based on location by the heart

Which structure will you see in every mediastinal part?

Esophagus

When do you see the thymus in the cranial mediastinum?

– In young animals

What structure is dominated in the cardiac mediastinum?

-heart

how does the L phrenic n run?

-drops down and runs to L side of heart

what is the plica VC?

-outpouching of mediastinum (not mediastinum proper)

-holds CaVC, R phrenic n

what is the pulmonary ligament?

-no strength

-not an actual membranous ligament

-area where mediastinal pleura becomes visceral pleura push against each other

-mediastinum to lungs

where does the pulmonary ligament extend?

caudally from principal bronchi → caudal part of lung

what is very important to note about the mediastinum?

-perforated

NOT CLOSED

what is the clinical significance of the holes in the mediastinum ?

-so the R and L sides can communicate

-but if there is a problem on one side it will affect both sides

definiton:

cupulae pleurae

pleural cups

-cranial part of pleural sac

-by thoracic inlet

definition:

costo-diaphragmatic recess

-”open” space between diaphragmatic and costal pleura

-lung does not go here

-during inspiration, diaphragm flattens and recess enlarges

• allows for some movt of lungs into space

costo-diapragmatic recess

what are the first two structures that come off trachea to lungs?

-principal bronchi

what structure comes off each bronchi and then to lung?

-2ndary bronchi OR lobar bronchi

what is the basic lung lobe pattern across all species?

-4 lobes on R

-2 lobes on L

which lung BORDER may extend into costo-diaphragmatic rececess?

-basal/diaphragmatic

what is the pluck view?

-if you were to hold the trachea, how the lungs fall into place
-view from dorsal

in terms of pluck:

location of dorsal border

-inside

pluck:

ventral border location

outside

pluck:

basal border location

costo-diaphragmatic recess

why do pigs and ruminants have an additional tracheal bronchus?

-R cranial lobe is quite large

-to support and allow more air need another tube

what is the general pattern of the lungs as animals get bigger?

(excluding eq)

-lungs get larger and more complex

which animal has the most complex lung?

-ruminants

which animal has a similar lung to ox?

-sheep

which animal does not have a middle lobe?

-horses

why is there a cardiac notch?

-during inspiration, the lungs expand

-need an area where lungs won’t crush heart

-sternal side

-heart will never touch sternum but close

definition:

hilus of lung

-root

-where everything attaches to mediastinum

-anchors lunch to trachea & heart