Valves And Vessels (and thorax radiography) Flashcards
What is the function of valves?
Prevent back flow of blood
Counteract gravity
What are valves supported by?
A fibrous skeleton
What is isovolumetric relaxation/contraction?
When the ventricles relax/contract but the volume of blood stays the same
No blood moves
What is a cusp?
The individual flap of a valve
What are valves attached by? What are they attached to?
Tendons (heartstrings)attached to papillary muscles
Which valves do not have tendons?
Semilunar valves
What causes blood to move?
Force from diastole
Recoil of arteries
Which 3 things control blood flow?
Precapillary sphincter zone Thoroughfare channels Arteriovenous anastomoses (connections)
What type of cells make up the endothelium?
Squamous
One cell thick
What do the intercellular clefts in endothelium cells do?
Allow diffusion (gap junctions)
How do large molecules move across the endothelial cells?
In vesicles
What do tight junctions in the epithelial layer do? Epithelial layers can be fenestrated, what does this mean?
Seal the endothelial layer
Perforated
What is a sinusoid?
A type of capillary in organs
What does collateral circulation mean?
There is more than one pathway of circulation
What are 3 types of arterial communications?
Collateral circulation
End arteries
Interarterial anastomoses
Interarterial anastomoses create side routes for circulation. What are interarterial anastomoses?
Vessels which connect one artery to another
What two veins make up the venae cavae?
Cranial VC
Caudal VC
The cranial vena cava leads to which major veins? (JACS)
Axillary (armpit), internal/external jugular, cephalic(head), subclavian (upper thorax)
The caudal vena cava leads to which major veins? (RITH)
Renal (kidney), iliac (pelvis), testicular/ovarian, hepatic (liver)
What are the names of the left and right coronary arteries?
L- caudosinistral sinus
R - cranial sinus
Why do tumours often spread to the lung?
Blood must pass through all lung capillaries as it cannot to another route
More likely to form tumour
When doing an x-ray of the thorax, why do both ventrodorsal and lateral views need to be taken? Why do both lateral views need taking?
2D image of 3D object
Laying on the side causes one lung to deflate- difficult to see
What is the cardiac silhouette?
The heart inside the pericardium
Why is the outline of the cardiac silhouette never clear? If it is, why is this?
Heart is beating so causing fluid to move in pericardium
Build up of fluid can cushion the beating
Why do fluid and tissue look similar on radiographs?
Similar density
