CVS Session 1 (Lecture 1.2) Flashcards
Which arteries branch from the aortic arch?
1) Brachiocephalic
2) Left common carotid
3) Left subclavian
What does the pulmonary trunk bifurcate into? Where does it arise?
Arises from right ventricle and bifurcates into right and left pulmonary arteries.
Where does the aorta terminate? Which arteries does it turn into?
Abdominal cavity bifurcating into left and right common iliac arteries.
What do arteries do?
Carry blood away from the heart to capillary beds.
What property of the aorta allows it to maintain pressure during diastole?
Contain elastic fibres and smooth muscle cells which recoil giving back energy gained from systole.
In what fashion is blood pressure observed near the heart?
Pulsatile
What are the three major types of artery?
1) Elastic conducting
2) Muscular distributing arteries
3) Arterioles
What are the three layers of an artery and vein?
Tunica intima, Tunica media, Tunica adventitia
What makes up the Tunica Intima of elastic arteries
Endothelium and subendothelium of CT with discontinuous internal elastic lamina.
What makes up the Tunica Media of elastic arteries?
40-70 fenestrated elastic membranes. SMC and collagen between lamellae. External elastic lamina may be present
What makes up the Tunica Adventitia of elastic arteries?
Thin layer of fibroelastic CT containing vessels, lymphatic vessels and nerves
What special feature is within the Tunica Adventita of elastic arteries?
Vasa vasorum
What makes up the Tunica Intima of muscular arteries?
Endothelium, subendothelial layer. Thick internal elastic lamina
What makes up the Tunica Media of muscular arteries?
40 layers of SMC (conncented by gap junctions for coordinated contraction). Prominent external elastic lamina.
What makes up the Tunica Adventitia of muscular arteries?
Same as elastic but not as many vasa vasorum
What do the nerves do in the tunica adventitia?
Release of NA to stimulate vasoconstriction by acting on SMC in the TM layer. Gap junctions allow depolarisation of all cells.
What do protuding endothelial cells indicate?
Vasoconstriction
What is an end artery?
Terminal artery supplying all or most of the blood to a body part without significant collateral circulation. They undergo extensive branching without the development of channels connecting with other arteries.
Give three examples of an end artery and two anatomically true examples
1) Coronary artery
2) Splenic artery
3) Renal artery
Anatomically correct:
1) Central artery to the retina
2) Labyrynthine artery of the internal ear
If an artery has a diameter less than 0.1mm what is it known as?
Arteriole
How many layers of SMC do arterioles have in their TM ?
1-3
What is present in large arterioles but absent in all arterioles?
Internal elastic lamina present
External elastic lamina absent
Define a metarteriole..
Arteries that supply blood to capillary beds.
How do they differ from arterioles? What is the special term for the SMC in metarterioles?
SMC layer is not continuous. They are spaced apart and each encircles the endothelium of a capillary arising from the metarteriole.
Called a precapillary sphincter
What does the PCS do?
Control blood flow into the capillary bed.
Can the capillary bed be bypassed? If so how?
Yes. Bypassed by the central channel (metarteriole + throughfare channel). Also known as a vascual shunt
What do the lymphatic capillaries do?
Drain away excess ECF returning it to the blood at the junctions of the internal jugular and subclavian veins.
Where is blood velocity at its lowest? Why?
Capillaries. Allows time for gas and nutrient exchange with surrounding tissues
What makes up a capillary?
Once cell thick endothelium and its basement membrane
What are the three types of capillaries?
1) Continuous
2) Fenestrated
3) Sinusoidal
Where can these capillaries be found?
Continuous - most common, located in nervous, muscles and CT, exocrine glands and lungs
Fenestrated - parts of gut, endocrine and renal glomeruli
Sinusoidal - liver, spleen and bone marrow
What are the defining features of each type of capillary?
Continuous - continuous endothelial layer (tight junctions and occludins)
Fenestrated - interruptions exist across thin parts of the endothelium.
Sinusoidal - slow blood flow, gaps exist allowing cells to move between blood and tissue
What are pericytes and what can they do?
Form a brancing network on the outer surface of the endothelium. They can divide into muscle cells, fibroblasts during angiogenesis, tumour growth and wound healing.
What are the four routes of transport across a wall of a fenestrated capillary?
1) Direct diffusion
2) Diffusion through intercellular cleft
3) Diffusion through fenestration
4) Pinocytic vesicle
Post capillary venules are similar to what vessel? What occurs due to their low pressure and what is special about them?
Capillaries.
Even more permeable and low pressure so fluid tends to drain into them except in an inflammatory response. Preferred site of leukocyte emigration from blood.
What signifies a venule?
50 micometre diameter with smooth muscle cells in the TM.
What aspect of venules stop retrograde transport of blood?
Valves
What are the main differences between an artery and a vein?
Veins have a larger diameter, thinner wall with more CT and fewer elastic and muscle fibres
What do small and medium size veins have?
Well developed TA with a thin TI and TM 2-3 layers of SM.
What do large veins have? (one exception is…?)
Diameter >10mm
TI is thick. TM is not prominent but well developed TA.
Exception are the superficial veins of the leg which have a muscular wall (resist distension by gravity)
What are vena comitantes?
Deep paired veins that (in certain anatomical positions) accompany one of the smaller arteries on each side of the artery. The veins appear to anastomose. The three vessels are wrapped in one sheath.
What is the advantage of vena comitantes?
Pulsing artery promotes venous return within the adjacent, parallel, paired veins
Name examples of vena comitantes.
Brachial, ulnar and tibial vena comitantes
What are the main features of large veins?
Well developed longitudinally orientated SM in TA and circular SM in TM.
Name some examples of large veins.
Vena cavae, pulmonary, portal, renal, internal jugular, iliac and azygous
What is the rate of lymphatic drainage back to the heart?
100ml/hr
