Anatomy of The CVS 2 Flashcards
What is similar between the heart endocardium and the tunica intima of blood vessels?
Both are composed of epithelium, basement membrane and connective tissue
What is the tunica media made from?
Muscle - equivalent to myocardium
What is the tunica adventitia made from?
Connective tissue
What are the three layers of blood vessels?
Tunica intima
Tunica Media
Tunica adventitia
Describe the epithelium in the tunica intima
Simple and squamous
Describe the tissue in the tunica media
Smooth muscle tissue and elastic tissue
Describe the tissue in the tunica adventitia
Fibrous connective tissue
Which is bigger, tha artery or the accompanying vein?
Accompanying vein
Which has a thicker wall, artery or vein?
Artery
Describe the thickness of the media and the adventitia in an artery and a vein
Thick media and thin adventitia in artery
Veins - Thin media and thick adventitia – needs more support
Describe the diamters and total cross sectional area in arteries
Diameters:
Arteries > arterioles > capillaries
Total cross sectional area:
Arteries < arterioles < capillaries
Describe the function of the tunica adventitia
Tunica adventitia, lots of connective tissue, collagen – connects to surrounding tissue
Where do you find elastic fibres in a muscular artery?
Just under the epithelium and in the space between the media and the adventitia
What are the types of arteries?
Elastic
Muscular
Arterioles
What are elastic arteries?
Large and conducting (aorta, common carotid, pumonary trunk)
LOTS of STRETCH
What are muscular arteries?
Distributing arteries
(coronary arteries, radial and femoral)
Conducitng fibres - not musch elastic
What are arterioles?
Terminal branches which supply blood to the capillary bed
When are the elastic arteries stretched?
During systole
How do elasticarteries maintain blood pressure?
Heart relaxes during diastole, pressure falls and the artery recoils
Where in the elastic arteries do you find extensive amounts of elastic fibres?
In the tunica media in the form of layers (laminae)
What are the elastic fibres sereted by?
Smooth muscle
Where are the muscle cells in muscular arteries?
In the thick tunica media
Is there elastic lamina between the muscle cells in the tunica media?
NO
Where are elastic fibres concentrated in the muscular arteries?
In 2 well defined sheets called the internal elastic lamina (IEL) just under epithelium and the thin outer elastic lamina (OEL) between T.media & T. adventitia
What does the tunica intima contain?
Endothelium, basement membrane NO internal elastic lamina
How many layers of smooth muscle are contained within the Tunica media in arterioles?
Only 1-2 layers
Is there tunica adventitia in the arterioles?
NO
Why are nerves found next to arterioles?
•Rich sympathetic nerve innervation
What is the role of arterioles?
- Control blood flow to capillary beds (local)
- Control blood pressure (systemic)
What is the main exchange site for nutrients and gases?
Capillaries
Describe the layers present in capillaries
Tunica intima only
What are pericytes?
Contractile cells that wrap around the endothelial cells of capillaries and venules throughout the body.
They help control flow of blood in the capillaries.
Why is the blood pressure in the capillaries low?
Sum of diameters of all capillaries in body > diameter of aorta
What are the three types of capillary?
Continuous
Fenestrated
Discontinuous
What is the difference between the basal lamina in fenestrated and discontinuous capillary?
Fenestrated = Complete basal lamina (contains protein diaphragms)
Discontinuous = Incomplete basal lamina (no protein diaphragms)
Where do you find a continuous capillary?
Muscle
How does a continuous capilllary work?
Can control what is exchanged
Material must pass through cell, or between cell (junctions can control)
Selective transport mechanisms
What are Fenestrations?
Pores in fenestrated capillary
What is the purpose of protein diaphragms in the fenestrated capillary?
Filter molecules by MW &/or charge
Where do you find fenestrated capillaries?
Endocrine glands, kidney renal corpuscle – when you need a bit of filtration
Where are gaps found in the discontinuous capillaries?
Between endothelial cells (and basement membrane)
What is the purpose of the gaps in the discontinuous capillaries?
Allow free passage of fluid and cells
Where do you find discontinuous capillaries?
Liver, spleen and bone marrow
SINUSOIDS ARE DISCONTINUOS CAPILLARIES
What are sinusoids?
Large diameter discontinuous capillaries
Where do you find sinusoids?
Found where large amount of exchange takes place
e.g: liver, some endocrine glands
What is contained within the tunica intima of the sinusoids?
phagocytic cells
What are arteriovenous shunts?
What is the names given to the types of vein from small to large?
Capillary bed - small venule - small- medium sized vein - large vein
What are the different layers in veins like?
T.intima is thin
Internal elastic lamina and external elastic lamina is thin or absent
T media is thin or absent
T adventitia os collagenous tissue
Valves – to prevent back flow – endothelial projections into lumen
What is the difference between superficial and deep veins?
Where are lymph nodes often found?
Alongside major veins and around origins of major arteries
What directs flow in the lymphatic system?
Valves
Describe lymph capillaries
Blind ended
Lined by very thin endothelium
No fenestrations
Absent / rudimentary basal lamina
Lumen maintained at negative hydrostatic pressure
Anchoring filaments – fine collagenous filaments link endothelial cell to surrounding tissue keeping lumen open
No red blood cells in the lumen
What is the name given to vessels of vessels?
Vasovasorum
Where do you find lymphatics in blood vessels (as organs)
Tissue adventitia
