Arteries And Veins Flashcards
What are the layers of blood vessels?
Tunica intima
Tunica media
Tunica adventitia
What do the layers of blood vessels consist of?
Tunica intima - simple squamous epithelium, basement membrane and connective tissue
Tunica media - smooth muscle (elastic tissue)
Tunica adventitia - connective tissue
Describe the difference in the structure of veins and arteries with regards to the layers.
Arteries are smaller in diameter than veins because it has a thicker wall
Arteries have a thicker tunica media
Veins have a larger tunica adventitia compared to arteries as it requires more support to attach it to its surroundings because it is floppy
Give 3 examples of elastic arteries.
Aorta
Common carotid
Pulmonary
Give examples of muscular arteries.
Coronary arteries
Radical artery
Femoral artery
Arteriosus are terminal branches which supply why?
The blood to the capillary beds
What is the difference between conducting and distributing arteries?
Conducting arteries are large elastic arteries such as the aorta.
Distributing arteries are muscular such as the coronary arteries
How does the elastic arteries such as the aorta act as a pressure reservoir?
Controls the pressure so during systole the pressure doesnt go too high and diastole to ensure pressure doesn’t drop too low.
The vessel i.e. aorta stretches during systole as the heart contracts and fills with blood and recoils during diastole as the heart relaxes.
What is the recoil and stretchability in elastic arteries due to the presence of?
Elastic fibres in the tunica media in the form of layers called laminae.
The fibres are secreted by smooth muscle.
In muscular arteries, there isn’t a lot of elastic fibres like the elastic arteries. Instead the elastic fibres are concentrated where?
In 2 sheets called the internal elastic laminate (IEL) just under the epithelium
and the thin external/outer elastic lamina (OEL) between the tunica media and tunica adventitia.
Histologically, what is the difference between arteries and arterioles?
There is no internal elastic lamina in the tunica intima
There is only 1-2 layers of smooth muscle
They only have 2 layers, they don’t have a tunica adventitia.
What is the nerve innervation of capillaries?
Sympathetic
What are pericytes and where are they found?
Pericytes are found in capillaries
They are an incomplete layer of cells which surround the basement membrane
They have contraction properties which help control flow of blood in the capillaries.
Why is the blood pressure in the capillaries low?
Because the sum of all the capillaries in the body is less than that of the aorta
What are the 3 types of capillaries?
Continuous
Fenestrated
Discontinuous
Describe the different types of capillaries.
Continuous - complete basal lamina
Fenestrated - complete basal lamina with fenestrated endothelial lining
Discontinuous - incomplete basal lamina and fenestrated endothelial lining
Where would you find a continuous capillary?
Muscle
Where would you find a fenestrated capillary?
Endocrine glands
kidney renal Corpuscle
(Where there is secretionsyou need pores
Where would you find a discontinuous capillary?
Liver, spleen, bone marrow
Where would you find sinusoids and why?
Find sinusoids where large amount of exchange takes place
I.e. liver, spleen, some endocrine glands
What cell does sinusoids contain that other capillaries don’t and where are these cells found?
Cinusoids contains phagocytes in their tunica intima.
What controls the flow through the capillary beds to allow arteriovenous shunt?
Precapillary sphincters
Describe arteriovenous shunts
Arteriovenous shunts is the diversion of blood flow from the capillary beds to the arterioles, so it bypasses the capillary beds
Give an example of where AV shunt would occur.
In the skin for thermoregulation
What prevents the backflow of blood in veins?
The presence of valves
Where do the valves in the veins arise from?
Endothelial cells in the tunica intima which project into the lumen
What’s the difference between superficial and deep veins?
Superficial veins are thicker walled and have no surrounding support
Deep veins have a thin wall but have surrounding support from deep fascia and muscles
What does the lymphatic system drain into?
Venous system
Describe the structure of lymph capillaries?
Lined by very thin endothelium
No fenestrations
collagenous filaments anchor endothelial cell to surround tissue keeping the lumen open
How can you differentiate between a lymph capillary and an arterial capillary?
There are no red blood cells in lymph capillaries
What’s the name for the blood supply of the blood vessels?
Vasa vasorum
Where do you find the vasa vasorum?
In the tunica adventitia
What type of connective tissue is the tunica adventitia?
Fibrous
What type of tissue does the tunica media contain?
Smooth muscle tissue
Elastic tissue
The internal thoracic artery bifurcates at which point? And what terminal branches does it divide into?
6th intercostal space the internal thoracic artery divides into the musculophrenic artery and the epigastric artery
