Blood Vessels Flashcards
What are the three layers of the wall of blood vessels
Tunica interna
Tunica media
Tunica externa
What is the tunica interna
Innermost layer of the blood vessel wall
endothelium, connective tissue (collagen, laminin, fibronectin, and other extracellular matrix molecules), and a basal layer of elastic tissue called internal elastic lamina
What is the tunica media
Middle layer
Mostly smooth muscle with elastic and collagen fibres
What is the tunica externa
Outermost layer
Mostly collagen and elastin fibres
Which tunica can help distinguish between veins and arteries
Tunica media
Which animals have a n azygous vein
All mammals but there’s some species variation
What is the function of the azygous vein
Drains dorsal mid/caudal thorax and L1-L2 region since the caudal vena cava dips ventrally to go through the liver.
Which animals have a right azygous only
Dogs, cats and horses
What animals have a left azygous vein only
Pigs
Which animals have a left and right azygous vein
Ox, sheep, goat
What is angiogenesis
The sprouting of new capillaries from pre existing vessels
What is vasculogenesis
The formation of blood vessels from endothelial progenitor cells (angioblasts from mesoderm)
When do angiogenesis occur
Feral/ post natal development as metabolicdaly active tissues need to be close to capillaries for gaseous exchange
Adult- female reproduction like placental development
Pathology- wound healing, tumour development
What causes angiogenesis
Hypoxia
Lack of oxygen so high amount of HIF
Endothelial cell tip secretes proteolytic enzymes
Causes capillary sprouts
What is the portal system
When a few organs are connect in series and they obtain their blood second band from the venous outflow of another organ
What is the advantage of the portal system
To transport a solute from one place to another without dilution in the general circulation
Whjdn animals have a hepatic portal vein
All vertebrae
Where does the hepatic portal vein go
From GI to liver
Which animals have the renal portal vein
All vertebrae except mammals
What does the renal portal vein do
From hind limbs to kidney
What is anastomosis
It’s a bridge of blood vessel that forms so that it can rescue the blood supply and avoid necrosis
What percentage of the blood volume is arteries
15%
What is the percentage of blood in capillaries
5%
What is the blood volume in the venules and veins
80%
What are the different layers of blood vessels
Endothelium
Tunica intima
Tunica media
Tunica adventitia
What is in the tunica intima and media
Smooth muscle
Collagen
Elastin
What is in the tunica adventitia
Collagen
Elastin
What is the diameter of the aorta
2cm
Which blood vessels contain collagen
All except capillary
Which blood vessels contain elastin
All except capillar and venule
Which blood vessels contain smooth muscle
All except capillary and venule
Which blood vessels contain collagen
All except capillary
Why is a high level of elastin and collagen important in the aorta
It dampens the oscillating cardiac output when the blood is pushed out the heart
Why do the artérioles have lots of smooth muscle
They can contract to increase blood pressure as diameter would increase
Can maintain high blood pressure and maintain reistance to blood pressure
Why do capillaries need a low blood pressure
No collagen or elastin, so very fragile
High pressures cause lots of fluid out (tissue fluid)
What are the three types of capillaries
Continuous
Fenestrates
Discontinued sinusoid
What are continuous capillaries and where are they found
Continuous lining of endothelial cells except for clefts between cells
Majority in body
What are fenerstrated capillaries and where are they found
Cell membrane is compressed to permit greater fluid transmission (creating windows)
In glomerular capillaries in kidney
What are discontinuous sinusoid capillaries and where are they found
Some wider intercellular gaps permit increased exchange with surrounding tissues
Liver, bone marrow, lymphoid tissue, some endocrine glands
What does the venous return depend on
Pressure difference between venules and RA
Smooth muscle contracts
Valves
Inspiration (abdominal compression)
Skeletal muscle movement
Gravity (upper body)
What are the main functions of blood circulation
To transport gases to and from organs/ tissues
To Deliver nutrients
To remove waste
To communicate
To maintain constant temperature
To maintain cardiac output pressure
