Structure Of Embryology And Circulation Flashcards
Why do we need circulation?
Very cell in our body needs to be bathed in fluid and within 2mm of a source of oxygen.
Overview of artery:
They have an elastic wall - which allows them to stretch and recoil - smooth pressure surges.
Major distribution vessels
Lumen Intima - Endothelial cells on basement membrane Media - smooth muscle Internal elastic lamina Adventitia - contains fibroblasts External elastic lamina
Note veins don’t have and blood supply can ru through the adventitia to supply it
Can red blood cells easily fit through a capillary?
No RBCs have to squeeze through capillaries as its diameter is small than that of the red blood cell.
This can can cause issues when pathology changes the shape of the cells such as sickle cell.
As capillaries are so small they will most likely be shown via electron microscopy.
What is the difference between a muscular and elastic artery?
Elastic arteries contain larger numbers of collagen and elastin filaments in their media than muscular arteries do, giving them the ability to stretch in response to each pulse. Elastic arteries include the largest arteries in the body, those closest to the heart, and give rise to the smaller muscular arteries.
Elastic arteries includes the aorta and the pulmonary artery
Veins structure and function…
See card before for structure.
They however also have veins to stop the back flow of blood and allow for muscular pumping.
The job of the veins is to return the blood back to the heart.
Capillaries overview:
They are the functional part of the circulation.
Regulated by capillary sphincters
Between 3–40 microns in diameter
3 x types = continuous (most common), fenestrated (kidney, SI, endocrine glands) and discontinuous (liver sinusoids) - allow large molecules in and out of blood stream.
What is Vasculogenesis =
process of blood vessel formation in an embryo occurring by the production of endothelial cells.
What is angiogenesis?
Formation of new blood vessels from pre existing vessels which were originally formed in Vasculogenesis
The process of vasculogenisis and angiogenesis in the embryo…
Day 17 - formation of blood islands (derived from mesoderm - core of hemoblast surrounded by endothelial cells).
Day 17-21 vascularisation of the yolk sac and the chorionic villus and stalk.
Day 18 - angioblasts (from mesoderm) coalesce join to form cords throughout the embryonic disc.
Angiogenesis is driven by growth factors (angiopoietin 1 and 2) as well as repulsive and attractive signals and takes place via growth and branding of previous blood vessels.
Describe the steps of aortic arch embryology?
At day 29 the remodelling of the aortic arch takes place.
There are 5 pairs of aortic arches numbered 1,2,3,4,6
The aortic arch is fully remodelled by 7 weeks and gives rise to arteries such as the subclavian, common carotid, pulmonary trunk etc etc
