CVS S1 Flashcards
What layers make up the pericardium? Answer from outermost to innermost.
The fibrous pericardium
The parietal layer of serous pericardium
The visceral layer of serous pericardium
What surrounds the heart?
The pericardium
Describe “venae comitantes”
A pair of veins (occasionally more) that accompany an artery in such a way that the pulse aids the return of venous blood to the heart. They share a sheath and appear to anastomose.
What are the names of blood vessel types in order from the left ventricle to the right atrium?
Large artery (elastic/conducting), medium artery (muscular/distributing), arteriole, metarteriole, capillary, post-capillary venule, venule, medium vein, large vein.
How much blood does the adult body contain?
5-6 litres
How much blood is pumped through the heart every minute at rest?
About 5 litres per minute
How many litres of blood are pumped through the heart every minute during exercise?
Up to 25 litres
How much fluid enters back into circulation via the lymphatic system per hour?
100ml per hour
What three major arterial trunks originate from the trunk of the aorta?
Brachiocephalic, common carotid and subclavian arteries.
Where does the aorta terminate?
In the abdominal cavity, where it bifurcated into the right and left common iliac arteries in the pelvis
What are the three layers of arteries and veins from outermost to innermost layer?
Tunica adventitia, tunica media, tunica intima
What are end arteries? Give examples.
End arteries are terminal arteries that supply most or all of the blood supply to an area of the body without significant collateral circulation. Eg, coronary, splenic and renal arteries.
What is a risk associated with end arteries?
If occluded, there will be very little or no circulation to the tissues downstream of the occlusion
What is a precapillary sphincter and where are they found?
Found in metarterioles in place of continuous smooth muscle as seen in the walls of arterioles. Made up of singly spaced smooth muscle cells, they help control blood flow to the capillary bed.
What are the types of capillary?
Sinusoid, fenestrated and continuous.
What are the main characteristics of continuous capillaries?
The most common type
Continuous endothelial layer
Have tight or occluding cellular junctions
Where can continuous capillaries be found?
Nervous tissue Muscle Connective tissue Lungs Exocrine glands
What are the main features of fenestrated capillaries?
Have “windows” or interruptions in the endothelial layer which are bridged by a thin diaphragm
Where can fenestrated capillaries be found?
Parts of the gut, the renal glomerulus and endocrine glands.
What are the main features of sinusoidal/discontinuous capillaries?
Larger diameter (30-40μm) Slower blood flow Gaps in capillary wall large enough for cells to pass through
Where can sinusoid capillaries be found?
Liver
Spleen
Bone Marrow
What is the diameter of a capillary?
7-10μm
What is the diameter of a postcapillary venule?
10-30μm
How are venules different from post capillary venules?
Continuous smooth muscle returns to the tunica media in venules, and the diameter is between 50μm and 1mm
If a vein is accompanied by an artery, do they have the same diameter?
No. The vein would have the larger diameter.
Describe the tunica of large veins
Reasonably thin tunica intima, thin tunica media, well developed tunica adventitia
EXCEPTION: leg veins- these have thicker smooth muscle layers in the tunica media, possibly to resist gravity.
What is the diameter of large veins?
> 10mm
How is venous blood returned to the heart?
Skeletal muscle contraction and valves act together
Where may venae comitantes be found?
Eg ulnar, brachial and tibial venae comitantes
Give some examples of large veins
Vena cava, pulmonary, portal, iliac, azygous and internal jugular veins
How much blood flows to the brain per minute?
750ml/min
How much blood flows to the heart per minute? (Minimum and maximum)
300-1200ml/min
How much blood flows to the kidney per minute?
1200ml/min
How much blood flows to the gut and liver per minute? (Min and max)
1400-2400ml/min
How much blood flows to the skin per minute? (Min and max)
200-2500ml/min
The large difference is due to use as thermoregulator
What are the general components of the cardiovascular system?
A pump (the heart) Distribution vessels (arteries) Flow control (resistance vessels) Capacitance- the ability to cope with blood volume changes (large veins store blood)
