5. Anatomy of the CVS 2 Flashcards
What are 3 main types of arteries?
- muscular
- elastic
- arteriole
Define function of the heart.
pumps blood around the body via circulatory system
Define function of arteries.
distributes blood away from heart
Define function of capillaries
exchange of gas and nutrients takes place there
Define function of veins.
collects and returns blood towards the heart
What are 3 layers which make up the heart?
- endocardium
- myocardium
- epicardium
What makes up the endocardium? (innermost layer) (3)
- epithelium (simple squamous)
- basement membrane
- connective tissue
What makes up the myocardium? (middle) (1)
cardiac muscle (myocardium)
What makes up the epicardium? (outermost) ( 3)
- connective tissue
- basement membrane
- epithelium ( simple squamous)
What are the 3 layers which make up the blood vessel?
- tunica intima (innermost)
- tunica media (middle)
- tunica adventitia (outermost)
What is tunica intima made up of? (3)
- epithelium (simple squamous)
- basement membrane
- connective tissue
What is tunica media made up of? (2)
- smooth muscle tissue
2. elastic tissue
What is tunica adventitia/externa made up of? (1)
- fibrous connective tissue
How do arteries differ from veins? (2)
- arteries are smaller in diameter than accompanying vein
- arteries have a thicker wall than accompanying vein
What is the difference in tunica media and adventitia between arteries and veins?
- arteries have a thick media and thin adventitia (muscly)
- veins have a thin media and a thick adventitia (support)
Compare arterial and venous lumens.
- arterial lumens are much smaller
- venous lumen is more floppy and dilated (wide)
What are the individual diameters of lumens in vessels carrying oxygenated blood in systemic circulation from biggest to smallest?
- artery
- arteriole
- capillary
Between arteries, arterioles and capillaries, name them from biggest to smallest total cross sectional area?
- capillaries
- arterioles
- arteries
What connects blood vessels to the surroundings? (2)
- collagen
- connective tissue
What colour are elastic fibres in histology slides?
blue
Where are elastic fibres concentrated and found in arteries?
- just under the epithelium (internal elastic lamina)
- between tunica media and tunica adventitia (thin external/ outer lamina)
What are examples of ELASTIC arteries? (3)
- aorta
- common carotid artery
- pulmonary artery
What are examples of MUSCULAR arteries? (3)
Distributing arteries:
- coronary arteries
- radial arteries
- femoral arteries
What types of arteries are arterioles?
terminal branches which supply blood to capillary bed and control the blood pressure
Why are elastic fibres required in elastic arteries?
- because the elastic arteries experience big changes in pressure
What effect do arteries have on blood pressure? (ie during systole and diastole)
- they are pressure reservoirs
- they are stretched during systole
- during diastole, the heart relaxes, pressure falls, the artery recoils thereby maintaining blood pressure on the blood
What is the recoil and stretchability due to?
due to the presence of elastic fibres in tunica media in the form of layers (laminae)
Where are elastic fibres found?
in the tunica media
What are elastic fibres in the tunica media secreted by?
smooth muscle
What are muscular arteries responsible for?
Distribution of blood to body regions
Describe tunica intima and media of muscular arteries
- tunica intima made of endothelial cells and basement membrane
- thick tunica media has smooth muscle cells
Is there elastic lamina between muscle cells in tunica media in muscular arteries?
No elastic lamina
Describe what is found in each of the blood vessel layers of arterioles.
- tunica intima; endothelium and BM, no internal elastic lamina (IEL)
- t media; only 1-2 layers of smooth muscle with no elastic
- t adventitia; NOT present
What rich innervation do arterioles have? What does it do
Rich sympathetic nerve innervation which control blood flow to capillary beds (local)
What do arterioles ultimately control?
Blood pressure (systemic)
In histology slides, how can you identify it’s a blood vessel?
it has RBCs inside its lumen on the histology slides
Why are capillaries thin walled?
for more efficient transfer of gas and nutrients
Describe the 3 blood vessel layers in capillaries.
- T intima present (endothelium on basement membrane) ONLY
- no T media
- no T adventitia
What types of cell do capillaries specifically have?
Pericytes
What do pericytes do in capillaries?
- incomplete layer of cells surrounding the basement membrane
- they have contractile properties which help control flow of blood in the capillaries
What is the average diameter of capillaries?
4-15 micrometers
Is the sum of all diameters of all capillaries in the body bigger than the diameter of an aorta?
Yes
Is the blood pressure in capillaries low or high?
low
What are 3 types of capillaries?
- continuous
- fenestrated
- discontinous
What is a continous capillary?
- endothelial cells fold in a circle ( folded in on itself in a complete circle)
- can control what is exchanged
- material must through cell or between cell (junctions can control)
- has selective transport mechanism
What is a fenestrated capillary?
- Gaps present which are window-ike as well as protein membranes
- has fenestrations (or pores) up to 100 micrometres
- with or without protein diaphragms
- diaphragms filter molecules by molecular weight and/or charge
What is a discontinous capillary?
- Capillary wall has huge gaps between endothelial cells and BM
- allows free passage of fluid and cells
- no proteins
Where can continous capillaries be found?
in muscle
Where can fenestrated capillaries be found?
endocrine glands, kidney renal corpuscle
Where can discontinous capillaries be found? (3)
liver, spleen and bone marrow
What type of capillaries are sinusoids?
large diamater DISCONTINOUS capillaries
Where are sinusoids found?
irregularly shaped discontinous capillary found where large amount of exchange takes place
What does the tunica intima of the sinusoids contain?
contains phagocytic cells
Where are sinusoids found? (2)
- liver
- some endocrine glands
What structures bypass capillary beds for blood re-distribution>
arteriovenous (AV) shunts
In what common example, are arteriovenous shunts formed in capillary beds?
in skin for thermoregulation (when temp is too high and body wants to lose more heat so redirects blood)
Describe movement of blood from capillary bed to vena cava. (what vessels involved)
- capillary bed
- small venule
- medium sized vein
- large sized vein
- vena cava
Describe the 3 blood vessel layers in veins and what they contain.
1, tunica intima: thin, IEL(internal elastic lamina) and OEL (outer elastic lamina) thin or absent
- tunica media: very thin or absent
- tunica adventitia: collagenous tissue
From which layer are valves in veins formed?
from endothelial projection (to prevent backflow)
What are features of superficial veins? (wall and surrounding support) (2)
- thick walled
- no surrounding support
What are features of deep veins? (wall and surrounding support) (2)
- thin walled
- surrounding support from deep fascia and muscles
How does superficial vein lie?
it lies on its own in the fascia
How does a deep vein lie?
it lies next to its corresponding artery (e.g. femoral vein lies next to femoral artery)
Describe the function of the lymphatic system.
- drains tissue fluid lost from blood capillaries
- drains fluid back into the systemic venous system
Where are lymph nodes generally found in terms of veins and arteries?
nodes found alongside
- major veins
- around origins of major arteries
What structures do lymphatic vessels have that are also found in the venous systems?
valves (direct flow of blood)
Why are lymph nodes clinically important?
important in tumour cell metastases
What are the features of lymph capillaries?
- blind ended capillaries
- ne fenestrations
- lined by very thin endothelium
What is the basal lamina like in lymph capillaries?
absent/ rudimentary/not fully developed basal lamina
What pressure is the lymph capillary lumen maintained at?
negative hydrostatic pressure
How is the lumen of lymph capillaries kept open?
due to anchoring filaments; fine collagenous filaments link endothelial cells to surrounding tissues keeping the lumen open
How would you distinguish blood and lymph capillaries in a histology slide?
no RBCs present in lumen of lymph capillaries
Where do blood vessels act “as organs”?
- nerve supply (sympathetic in skin or sympathetic and parasympathetic in heart)
- blood supply (vasa vasorum)
- lymphatics ( in tunic adventitia)
What does vasa vasorum mean?
“vessels of the vessels”
vessels feeding nutrients to other vessels
