Blood vessels L8 Flashcards
What are all blood vessels lined with?
endothelium
-Lines ALL BV blood vessels
_Thin Flattened layer of cells
-provides a slippery and Smooth surface for the inside of all BV blood vessels
What is endothelium?
endothelium Lies ALL BV blood vessels
Is a Thin Flattened layer of cells
provides a slippery and Smooth inner surface for all blood vessels
What is the function of elastic fibres?
allows the vessels to Stretch
Which fibres in blood vessels allow them to stretch?
Elastin fibres
What is the function of smooth muscle fibres?
Wrapped around blood vessels
allows the BV to change diameter (via vasoconstriction and vasodilation)
Which fibres in blood vessels allow them to change diameter?
Smooth muscle fibres
- they Wrap around BV
- Allows them to change diameter(via vasoconstriction and vasodilation)
How do blood vessels change diameter?
via vasoconstriction and Vasodilation of the Smooth muscle which is wrapped around the BV blood vessels
What is the function f collagen fibres?
tough, inelastic strand
Prevent the vessel wall from stretching to a point of rupture
Which fibres present in blood vessels are there for the most structural support?
Collagen fibres
- are Tough and Inelastic strands
They prevent the vessel wall from stretching to a point of rupturing
Which fibres are touch and inelastic, and prevent the blood vessel wall from stretching to a point of rupture?
collagen fibres
Are collagen fibres elastic or inelastic?
Inelastic
- they are tough, inelastic strands of CT
- Prevent the blood vessels wall from stretching to a point of rupture
How many classes of blood vessels are there in the Cardiovascular system?
7
Heart –> 1. elastic arteries –> 2. muscular arteries –> 3. arterioles –> 4. capillaries –> 5. venules –> 6. veins –> 7. coronary arteries
What are the 7x classes of blood vessels there are in the cardiovascular system, in order, beginning from the heart?
Heart
- elastic arteries –>
- muscular arteries –>
- arterioles –>
- capillaries –>
- venules –>
- veins –>
- coronary arteries
What is the relationship between the orientation of exit of the aorta and pulmonary trunk?
Aorta twists around the pulmonary trunk during exit
What are features of arteries in general?
- Plenty of elastin fibres
- therefore high compliance
- Wall can therefore be easily stretched or expand
- Or walls can be thicker as there is more pressure
- Gradual change in vessel thickness as it leaves heart
Heart –> finger thick Elastic arteries –> pencil to pin thickness of muscular arteries (range due to smooth muscle’s ability to change diameter (r4 effect on flow) and can distribute out to rest of body (reason for control of flow as blood doesn’t flow entire body at once, needs to be directed to where is needed)) –> hair thing arteriole
In general, what type of fibres is found in reasonable abundance in all arteries?
Elastin fibres -allows for: high compliance ability to stretch and expand walls to become thicker due to higher pressure
What are the main features of Elastic arteries?
- Pulse and Pressure Absorbers
- They take they brunt of the pressure of the pump
- also called Conducting arteries
- less than 1cm in size - size of a finger
- Is the first vessels which leave the heart (approx. first 15cm)
- Largest arteries
- effects the rate of Ejection (from the ventricle) and run off (leaving elastic arteries into arterial tree)
- contains Thin sheets of up to 50 sheets of Fenestrated Elastic fibres. found in the Middle tunic
- high proportion of elastin fibres, designed to be stretchy. Thin comparatively. Results in a Big, Eleatic, rubbery, soft artery - During systole: Heart is trying to Reduce volume. In turn generates pressure. Expands the store fore the bolus of blood which is leaving the ventricle. Ek –> Eep. More blood enters the elastic artery than can exit into the arterial tree (therefore the elastic arteries expands to accommodate) (rate of ejection>rate or run off into arterial tree)
- During Diastole: the bolus of blood that is being stored in the elastic artery Is pushed out into the Arterial tree via Elastic recoil. (Eep –> Ek), results in an absorption of pressure and a Smooth instead of pulsatile flow of blood leaving the ventricle
- allows the blood to be ALWAYS flowing down the arterial tree- as cells need a constant, not pulsatile, supply of blood, therefore this elastic recoil allows the supply to be constant (pressure absorber)
What is the overall name for elastic arteries?
Pulse and Pressure absorbers
-they take the brunt of pressure from the ventricle ejecting and absorbing it through energy conversion (Ek –> Eep –> Ek)
Conducting arteries
What are the Pulse and Pressure absorbers of the cardiovascular system?
Elastic arteries
What is another name for elastic arteries?
Conducting arteries
What is another name for conducting arteries?
Elastic arteries
What is the size of a finger?
Elastic arteries
What is the relative size of an elastic artery?
size of a Finger
Less than 1cm
Which arteries are they largest?
Elastic arteries
Less than 1cm width, FINGER size
-muscular arteries are pencil –> pin
-arterioles are hair
What two rates are there being controlled by elastic arteries?
rate of:
Ejection (pushed out of ventricle)
Run off (out of elastic arteries)
What is the structure of Elastin arteries?
up to 50 sheets of fenestrated elastin
Located in middle functional tunic
Thin comparatively
-designed to be stretchy
How many sheets of fenestrated elastin are there in elastic arteries’ middle tunics?
up to 50 sheets of Fenestrated elastin
Thin comparatively
Fenestrated elastin found in Middle tunic (functional layer)
-designed to be stretchy
What do elastic arteries look like?
First part leaving the heart
Rubbery, thin, Big/width, Elastic , soft arteries
How does the run off of stored blood in the elastic artery get pushed out into the arterial tree?
Via elastic recoil
When does elastic recoil come into use?
when the stored blood (with stored Eep) is pushed out into the arterial tree
What is the function of elastic recoil?
To allow blood flow to the cells in the arterial tree to be Constant and not pulsatile
Ensure that blood will always be flowing down the Arterial tree
- Cells need a constant, not pulsatile, supply of blood, the is contributed by the elastic arteries, actin g as a pressure absorber, and using leastic recoil for continuous distribution/flow of plod into the arterial tree
Which part of the vessels has the initial impact on the constant smooth (not pulsatile) flow of blood?
elastic arteries
What happens to elastic arteries during systole?
During systole:
Heart is trying to reduce volume
In turn it generates Pressure (contraction of ventricular walls ejecting blood)
Elastic arteries Expands
This expansion allows for accommodation of storage of the bolus of blood which is being ejected out of the ventricle
Ek –> Eep
More blood is ejected into/enter the elastic artery then can run off into the arterial tree (therefore the elastic arteries expand to accommodate)
Rate of ejection > rate of run of into the arterial tree
What happens to elastic arteries during diastole?
During Diastole:
The bolus of blood that is being stored in the elastic artery is Pushed out into the arterial tree via elastic Recoil
Eep –> Ek
Results in the Absorption of pressure
Smooth > instead of pulsatile, flow of blood leaving the ventricle
This elastic recoil allows the blood to be Always flowing down the arterial tree
Required as cells need a constant (not pulsatile) supple of blood. Elastic recoil allows supply to be constant (pressure absorber) and is the initial point of control of this supply to tissue cells in arterial tree/body
What type of Arteries are more common?
Muscular arteries
Are elastic or More less or same in abundance?
Muscular arteries are More common
What are the main features of muscular arteries?
- Most abundant artery (more than elastic arteries)
- 0.1mm –> 10mm (pencil–> pin diameter) 3-40 layers of smooth muscle
-this change in diameter is due to the muscular arteries’ smooth muscles’ ability to contract and change radius which has a huge effect on flow rate, which is after all its function - Functional/physical layer of Tunica Media contains More smooth muscle than elastin fibres in muscular arteries
- Tunica/layer outlay present in Every wall is MOST DISTINCT/BEST REPRESENTED in muscular arteries
- Tunica Externa: elastic and collagen.
Tunica Media: Mostly Smooth muscle (for functional role of vasoconstriction and vasodilation to change radius and hugely impact flow (hence diameter range of pencil –>pin)). THICKEST layer
3-40layers of smooth muscle
Tunica Interna/Intima: Inner elastic fibres lamina + Basement Membrane BM(physical support) + Endothelium
6.Distribution of blood. 1. around the body at high pressure. 2. around the lungs at medium pressure
distribution of blood is via BULK TRANSPORT - Rate of blood flow is adjusted by using smooth muscle (bulk Tuning) 3-40 layers. This varies the radius of the vessel depending on how much is needed via SYMPATHETIC CONTROL (causes vasoconstriction or vasodilation)
- Flow proportional to r^4
small radius change = large impact on rate of flow
allows muscular arteries to have a big diverting power , and allows the diversion of blood around the body to be needed by the control of sympathetic nervous activity, to be fast signalled and acting due to this power over flow
What is the size of a muscular artery?
Pencil –> pin
0.1mm - 10mm
this change in diameter is due to the muscular arteries’ smooth muscles’ ability to contract and change radius which has a huge effect on flow rate, which is after all its function
3-40 layers of smooth muscle
What is the thickest layer in muscular arteries?
tunica MEDIA
functional/physical layer of wall
In muscular arteries = Mostly Smooth muscle 3-40 layers (for functional role of vasoconstriction and vasodilation to change radius and hugely impact flow (hence diameter range of pencil –>pin)). THICKEST layer
What are the 3x components of the Tunica Interna/Intima of Muscular arteries?
- Thin sheet of elastin fibres/lamina
- BM basement membrane (for physical support)
- Endothelium (thin slipper flattened layer of cells lining all blood vessels)
What is the role of the basement membrane?
Physical support
Which blood vessel has the biggest impact on Bulk Transport?
Muscular arteries
-rate of blood flow is adjusted by smooth muscle’s Bulk TUNING
How many layers of smooth muscle is located inside the tunica media of muscular arteries?
3-40 layers of smooth muscle
-less as gets closer to arterioles
How is smooth muscle on controlled?
Radius change (vasoconstriction and dilation) is controlled via SYMPATHETIC CONTROL -as don't have a big enough supply of blood to overload entire body all at once, instead have enough to distribute proportion where it is needed - this is signalled quickly via sympathetic control (allows distribution of blood to be fast) and is done by the vasoconstriction and vasodilation of blood vessels
What allows blood distribution, mainly controlled by muscular arteries, to be so fast?
sympathetic nerve activities which causes vasoconstriction and vasodilation of smooth muscle in the media tunica of muscular arteries
What is the relationship between radius and flow?
Flow proportional to r^4
-small radius change = large change in flow
=give muscular arteries strong diverting power and allows the direction of blood guided by sympathetic nerve activity to be fast signalled and acted
What is the smallest muscular artery?
Arterioles
What can arterioles also be called?
Smallest muscular artery- but with a different function
What are the main features of arterioles?
1 smallest muscular artery - but with its own function.
wrapped around has 1-3 layers of smooth muscle in middle tunic + endothelium
2. controls the blood flow into the capillary beds
3. Is the site of Final Fine tuning
4. Hair thickness/Thin 10-100 micrometres, but have a thick Muscular wall which is half the size of the lumen
-this allows arterioles to have the thickest muscular wall/strongest vessel relative to their size
-allows it to still be small but have this effective final fine control/tuning as it becomes a capillary (avoiding them from bursting due to high pressure)
5.Has the Greatest resistance across them
6. Has the Greatest Pressure drop, and the Greatest Resistance to flow
7.the Degree of constriction of the arterioles throughout the body prior to the arterioles (all the pressures added up) determines the Total Peripheral Resistance
-PERIPHERAL - hence throughout entire body BEFORE arterioles
8. this TPR influences mABP mean Arterial Blood pressure
9. Arterioles have a big impact on things UPstream
10. artioles face a constant juggle between how much the heart will put out and how much the arterioles with encounter
What are capillaries the site of?
Final Fine tuning
Last responsibility of control
What is site of final fine tuning/last responsibility of control?
Arterioles
-controls the blood flow into the capillaries - so that the capillaries don’t burst as they are only made up of endothelium with no structural support
What is the size of the arterioles?
Hair thickness- microns
But has a thick muscular wall which is half the size of the lumen
-arterioles have the thickest muscular wall/strongest vessel relative to their size
-enables it to still be small but have this effective final fine tuning as it becomes a capillary (avoiding them from bursting due to high pressure)
What is an extremely important role of the arterioles regarding their size?
Arterioles are hair thickness, but have a thick muscular wall which is half the size of its lumen
this enables the arteriole to be the blood vessel with the thickest muscular wall/strongest vessel relative to its size
-enables it to still be small but have this effective final fine tuning as it becomes a capillary (avoiding them from bursting due to high pressure)
Which vessel has the greatest resistance across them?
Arterioles
What is the relationship between arterioles and resistance?
Arterioles have the greatest resistance across them
Compare the functions of arteries and arterioles?
Arteries: Bulk flow (bulk tuning)
Arterioles: Fine tuning
Where does bulk flow occur?
arteries (muscular)
Where does fine tuning occur?
arterioles
Where does bulk tuning occur?
arteries (muscular)
Where is the greatest pressure drop?
Arterioles
What 2x things does the arterioles contains the greatest amount of?
- Greatest PRESSURE DROP
2. Greatest RESITANCE (to flow)
What does the total Degree of Constriction thought the enter body prior to the arterioles (all pressures added up) determine?
Total Peripheral Resistance
-hence PERIPHERAL
What determines Total Peripheral Resistance?
TPR is the TAP on the arteriole diagram
the DEGREE OF CONSTRICTION throughout the entire body prior to the arterioles (all the pressures added up)
hence -PERIPHERAL
= Note: TPR influences mABP -assuming heart output is the same
What influences mABP Mean Arterial Blood pressure?
Total Peripheral Resistance
-TPR is determined by the Degree of constriction throughout the entire body prior to the arterioles added up
What does TPR Determine?
mABP
Mean Arterial Blood Pressure
-assuming same heart cardiac output
Where do arterioles have a big impact?
UPstream
Do arterioles have a smaller impact upstream of downstream?
Arterioles have a bigger impact Upstream
therefore smaller impact downstream
What are 2x constant juggles faced by arterioles?
- How much blood the heart is going to put out CO
2. how much Resistance the arterioles will encounter
Which blood vessel has to constantly face 1. the CO cardiac output of the heart and 2. the quantity of resistance it’ll have to face during its function?
Arterioles
What are arterioles composed of?
wrapped around it 1-3 layers of smooth muscle in media tunica
+ inner endothelium
How many layers of smooth muscle are in arterioles?
1-3 layers
What are the comparisons between Arterioles and their companion vein?
Lumen of vein is larger
Wall of artery is larger
This difference results in a pressure difference
use RBC as a scale bar - if RBC looks small = big lumen. If RBC looks big = small lumen.
Where does the arterial tree end?
Before capillaries
Therefore at arterioles
What do capillaries resemble in relation to the pumps, arteries and veins?
End of the atrial tree (arterioles)
soon
beginning of venous side (venules)
What are the key features of capillaries?
- Site of exchange (gases, nutrients and wastes)
- size of a RBC (4-10 microns) very thin
- Only Tunica Interna INTERNAL fenestrated endothelium + EXTERNAL BM basement membrane
NO smooth muscle - therefore CANT adjust its diameter
NO CT connective tissue - therefore no structural strength to resist tension - therefore cant resist tension
–no smooth muscle or ST connective tissue emphasizes its need for flow rate to be slow because it has nothing to manipulate/advantage exchange. it just has to be slow - Exchange is not direct. consists of 2x steps. Capillary Tissue/Fluid cells. Double exchange system.
tissue fluid is the Medium between the exchange between capillaries and cells
Capillaries exchange with interstitial fluid, DONT directly interact with cells. Do directly interact with Tissue/Interstitial fluid.
Interstitial fluid the Medium between capillaries and tissue cells. Pale yellow (blood plasma-what appears when you don’t cut blood vessels). this fluid acts like a gutted, BATHES everything in interstitial fluid. Essential is blood plasma/sourced from capillaries.
Cells
Overall: double Exchange system - To aid exchange, blood flow is slow, due to small width of capillaries (only wide enough to fit one RBC). RBCs slow as they bump against side of capillary.
- Capillaries are LEAKY vessels (fenestrated/same capillaries have Gaps) Gaps = big enough for blood plasma to escape to interstitial fluid exchange, indirectly exchanging with tissue cells. Gaps ARENT big enough for RBC or BIG PROTEINS (therefore CELL NUMBER stays constant in capillaries - only overall volume changes)
- Hydrostatic pressure is the pressure which drives fluid OUT of capillaries
- role of osmotic gradient. MAJORITY of the LOST of the lost plasma is IMMEDITAELY RECOVERED due to the OSMOTIC GRADIENT drawing the fluid back into the capillary (but not all the fluid)
- Excess fluid which ISNT drained back in by the osmotic gradient is Drained back in by the LYMHATIC system - think of Simon malpez funky diagram and equation lecture
What are capillaries the site of?
- Site of exchange (gases, nutrients and wastes)
What is the size of capillaries?
- size of a RBC (4-10 microns) very thin
- Only Tunica Interna INTERNAL fenestrated endothelium + EXTERNAL BM basement membrane
NO smooth muscle - therefore CANT adjust its diameter
NO CT connective tissue - therefore no structural strength to resist tension - therefore cant resist tension
–no smooth muscle or ST connective tissue emphasizes its need for flow rate to be slow because it has nothing to manipulate/advantage exchange. it just has to be slow - Exchange is not direct. consists of 2x steps. Capillary Tissue/Fluid cells. Double exchange system.
tissue fluid is the Medium between the exchange between capillaries and cells
Capillaries exchange with interstitial fluid, DONT directly interact with cells. Do directly interact with Tissue/Interstitial fluid.
Interstitial fluid the Medium between capillaries and tissue cells. Pale yellow (blood plasma-what appears when you don’t cut blood vessels). this fluid acts like a gutted, BATHES everything in interstitial fluid. Essential is blood plasma/sourced from capillaries.
Cells
Overall: double Exchange system - To aid exchange, blood flow is slow, due to small width of capillaries (only wide enough to fit one RBC). RBCs slow as they bump against side of capillary.
- Capillaries are LEAKY vessels (fenestrated/same capillaries have Gaps) Gaps = big enough for blood plasma to escape to interstitial fluid exchange, indirectly exchanging with tissue cells. Gaps ARENT big enough for RBC or BIG PROTEINS (therefore CELL NUMBER stays constant in capillaries - only overall volume changes)
- Hydrostatic pressure is the pressure which drives fluid OUT of capillaries
- role of osmotic gradient. MAJORITY of the LOST of the lost plasma is IMMEDITAELY RECOVERED due to the OSMOTIC GRADIENT drawing the fluid back into the capillary (but not all the fluid)
- Excess fluid which ISNT drained back in by the osmotic gradient is Drained back in by the LYMHATIC system - think of Simon malpez funky diagram and equation lecture
