Blood Vessels Flashcards
3 layers of blood vessel walls
- Tunica interna
- Tunica media
- Tunica externa/adventitia
Tunica interna
- structure
- one function
- structural difference in larger arteries
- Endothelium –> simple squamous epithelial layer
- Secretes endothelins (hormones) = interact w smooth muscle (constrictive or dilatory effects)
- Have an internal elastic membrane next to BM
Tunica media
- structure x2
- one function
- Concentric smooth muscle cells
- Varying amounts of elastic fibres –> in laminae (concentric)
- Vasoconstriction –> to increase BP
Tunica externa/adventita
- structure
- one function
- its blood supply
- Longitudinally orientated connective tissue (primarily collagen)
- Holds vessel together
- By vasa vasorum
Vascular tree
Heart –> elastic artery –> muscle artery –> arterioles –> capillaries –> venules –> medium veins –> large veins –> heart
Elastic arteries
- structure
- function
- Thick wall w lots of elastic tissue
- Expand during systole & relax during diastole –> elastic recoil
Muscular arteries
- structure
- function
- Thick layer of circular muscle in tunic media
- Controls distribution of blood to regions through construction & relaxation
Metarterioles
- structure x2
- Same diameter as capillary
- Smooth muscle in walls
Atheroma
- what
- consequences
- Plaques in arteries
- May form a thrombus (blood clot) –> vascular occlusion
Capillaries
- structure x2
- form…
- Simple squamous epithelium
- BM splits to enclose pericytes
- Capillary beds
What regulates blood flow in capillary beds
Pre-capillary sphincter
Function of pericytes in capillaries
Look after endothelial cells
3 types of capillary
- Continuous
- Fenestrated
- Sinusoid
Continuous capillaries
- structure x2
- Tight junctions between cells
- Vesicles for transportation
Most common
Fenestrated capillaries
- structure x2
- Circular fenestrae/pores
- Larger molecules can cross
Sinusoid capillaries
- structure
- location
- Bigger gaps
- In v specialised areas, so much less common
Venules
- % of blood at rest
- structure x2
- 60-70%
- Thin walls
- Valves
Artery vs vein x3
- Vein nearly always bigger (wider lumen)
- Vein = thinner wall
- Vein collapses, artery retains round same as more smooth muscle
3 vessels out of the top of the aorta
- Brachiocephalic trunk
- Left common carotid artery
- Left subclavian artery
What does the brachiocephalic trunk split into? x2
- Right subclavian
- Right common carotid
How do the common carotid arteries split?
Into the internal left/right & the common
How do the subclavian arteries split?
Into the vertebral
What blood vessels supply the head & neck?
Common & internal carotid
What blood vessels supply the brain?
Vertebral arteries provide a co-lateral supply
Names of the subclavian artery as it goes down the upper limb x3
- Subclavian
- Axillary
- Brachial
How does the brachial artery split?
Into radial & ulnar artery
Anastomoses
- what
- function
- example
- When one vessel plugs into another
- Co-lateral supply that allows for flow beyond a joint if a vessel gets occluded during movement
- e.g. superficial & deep palmar arches
Superficial & deep palmar arches
- what
- where
- Anastomoses
- Arches in hand formed from radial & ulnar arteries
- Descending from the aorta, it becomes….
- Descending thoracic aorta becomes common iliac artery
What do trunk arteries supply?
Segmental blood supply to abdominal & thoracic wall
How does the common iliac artery split?
Into left and right common iliac artery
How do the left and right common iliac arteries split?
- & what do they supply
- Internal iliac –> supplies pelvis
- External iliac –> continues into lower limb
What does the external iliac artery become?
The femoral artery
Femoral artery
- where does it lie
- lies alongside…
- becomes…
- Femoral triangle
- Femoral vein & nerve (vein –> artery –> nerve)
- Popliteal artery
Main blood supply to the thich
= Profunda femoris (deep femoral artery)
Sequence of thoracic arteries
- Aorta
- Descending thoracic aorta
- Common iliac artery
- -> splits left & right
- -> splits internal & external
Sequence of upper limb arteries
- External becomes the femoral artery
- Becomes the popliteal
Sequence of lower limb arteries
- Poplital
- Splits –> anterior tibial & tibio-peroneal trunk
- Tibio-peroneal trunk splits –> peroneal & posterior tibial
Lower limb veins
- 2 types
- Deep
- Superficial
Lower limb - deep veins
- location
- naming them
- Accompany limb arteries
- Share names of the arteries
Lower limb - superficial veins
- location
- function
- examples x2
- More superficial
- Communicate w deeper veins via perforating veins
- Great Saphenous Vein
- Small Saphenous Vein
How is blood pooling avoided in the lower limb veins? x3
- Venous muscular pump
- Veins run through muscles –> muscles contract –> blood forced up
- Valves prevent backflow
Superficial upper limb veins
- Medial side
- Lateral side
- Meeting point
- Basilic vine
- Cephalic vein
- Antecubital fossa (joined by medical cubital vein)
Abdominal veins
- e.g. vein mirroring common iliac artery
- converge upon…
- Common iliac vein
- Inferior vena cava
Inferior vena cava location x2
- Runs up right side
- Behind liver into heart
Venule equivalent of internal & external carotid arteries
- & what they drain into
- Internal & external jugular veins
- Brachiocephalic veins
Azygous vein
- location
- what drains into it
- what it drains into
- Along vertebral column (between IVC & SVC)
- Veins in posterior thoracic wall (e.g. intercostal veins)
- SVC
GI veins
- why different from other body systems
- via…
- Nutrients are absorbed - so transported straight to liver (not all the way around the system)
- Hepatic Portal Vein
What are vasa vasorum?
‘Vessels of the vessel’
- Smaller vessels branch into the outer part of the media of larger vessels
Internal elastic lamina
- where
- structure
- function
- End of tunica intima
- Layer of fenestrated elastic tissue
- Takes full force of systolic output
Artefacts in histology of aorta
Radial spokes (folds, crinkles in aorta) - Due to elastic fibres
Difference in structure between elastic & muscular arteries
- Tunica media: muscular = mainly muscle fibres vs elastic
Arterioles
- structure x2
- function x2
- Thick wall, narrow lumen
- Prominent layers of smooth muscle but not a clear adventitia
- Resistance to cardiac output
- Controls blood distribution (vasoconstriction & dilation)
Venules
- structure
- function
- Thinner wall = very permeable
- More permeable than capillaries –> site of fluid formation (e.g. exudate)
Arteriole vs venule x3
Venule =
- Normally bigger
- Larger lumen
- Less smooth muscle
In what vessel is there the biggest pressure drop?
Arterioles
