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MedSci142 > Lecture 8 - Blood Vessels > Flashcards

Lecture 8 - Blood Vessels Flashcards

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1
Q

What is referred to as the plumbing of the heart?

A

Blood vessels

Delivery of Oxygen and Nutrients to the body

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2
Q

What are all blood vessels lined with?

A

SLIPPERY,SMOOTH surface of ENDOthelium (thin flattened layer of cells)

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3
Q

What is the role of Elastin Fibres?

A

Allow vessels to stretch

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4
Q

What is the role of Smooth Muscle Fibres?

A

Smooth Muscle Fibres are wrapped AROUND vessels allowing the DIAMETER to be ADJUSTED

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5
Q

What is the role of Collagen Fibres?

A

Collagen Fibres are TOUGH, INelastic STRANDS which PREVENT the vessel wall from STRETCHING to the point of RUPTURE

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6
Q

What is the role of Arteries?

A

Arteries carry blood away from the heart
Arteries have plenty ELASTIC fibres so have High COMPLIANCE - so walls can Easily STRETCH or EXPAND . and the walls are also THICKER as there is more pressure

heart has LARGE ELASTIC arteries, which divide into MEDIUM size MUSCULAR arteries which BRANCH OUT into various regions of the body (gradual (charge or vessel))

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7
Q

What sort of arteries does the Heart consist of?

A

LARGE ELASTIC arteries, which divide into MEDIUM size MUSCULAR arteries which BRANCH OUT into various regions of the body (gradual (charge or vessel)

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8
Q

What are Elastic Arteries?

A

also called CONDUCTING arteries
Elastic Arteries are the FIRST VESSELS which LEAVE the heart (first 15 cm)
they are GREATER than >1cm (FINGER size)

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9
Q

What is the Function of Elastic Arteries?

A
  1. very LARGE arteries NEAR the heart which have ELASTIC WALLS
  2. during SYSTOLE (contraction) the heart is trying to Reduce Volume, generating More Pressure. Elastic arteries EXPAND to STORE the BOLUS of blood Leaving the ventricle. The KE from contraction is converted and STORED as ELASTIC ENERGY.(for use in diastole)
  3. during DIASTOLE (relaxation) elastic arteries PUSH blood OUT into the ARTERIAL TREE by ELASTIC RECOIL of the elastiN SHEETS in the elastic artery wall. Elastic Energy is converted to KINETIC ENERGY. SMOOTHS out the PULSATILE nature/flow of pump/blood Leaving the Ventricles. Will only pump in SHORT SPURTS every second with the elastic arteries expanding and contracting to accommodate that.
    (PRESSURE ABSORBER)(rigid pipes would transmit pressure through the arterial tree, and your Capillaries CANNOT HANDLE High Pressure)
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10
Q

What is the Structure of Elastic Arteries?

A

THIN SHEETS of ELASTIN in the MIDDLE tunic
acts as a PRESSURE RESERVOIR
Elastin has a Higher Proportion of Elastic Fibres (layers of up to 50 SHEETS of elastin fibres)-good at storing elastic energy and recoiling
Walls THIN comparatively

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11
Q

Which is easier to see, arteries or veins?

A

arteries

veins collapse and fold onto itself without blood

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12
Q

What is the first branch of the aorta called?

A

Brachiocephalic artery

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13
Q

What are the main qualitative features of arteries?

A

rubbery
soft
pliant

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14
Q

What is a bolus?

A

a “lump” of blood

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15
Q

What is the nature of the cardiovascular pump?

A

pulsatile nature of blood/pump flow

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16
Q

What do Elastic Arteries Always do?

A

Elastic arteries ALWAYS are pumping blood down the ARTERIAL TREEE, EVEN during Filling

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17
Q

What is a comparison between Muscular arteries and Elastic arteries?

A

Muscular Arteries are MORE ABUNDANT than elastic arteries

more common

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18
Q

What are Muscular Arteries?

A

0.1 - 10mm diameter
pen –> pin

Muscular Arteries as Tunica Media has More SMOOTH MUSCLE and Fewer elastin fibres than Elastic arteries

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19
Q

What is the Function of Muscular Arteries?

A

“coarsely channel”/DISTRIBUTE blood around the body at HIGH PRESSURE (and the LUNGS at MEDIUM pressure)
very good at DIVERTING blood to WHERE it is NEEDED
BULK Transport
the Rate of blood flow is adjusted via BULK TUNING using SMOOTH MUSCLE (2-40 layers) to VARY the RADIUS of the vessel depending on how much pressure is needed via SYMPATHETIC NERVOUS CONTROL.
Vasoconstriction (narrowing of diameter)
vasodilation (increase in diameter)
Flow is proportional to the FOURTH power of the Radius
therefore a SMALL CHANGE in radius has a LARGE EFFECT on the flow rate

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20
Q

How is the flow of blood calculated in Muscular Arteries?

A

The flow of blood in MUSCULAR arteries is proportional to the FOURTH POWER of the RADIUS

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21
Q

What is the structure of Muscular Arteries?

A

consists of 3x TUNICs (outer, middle and inner tunics)

Externa –> Media –> Intima/Interna

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22
Q

What does the Externa consist of?

A

Tunica EXTERNA =Outer Tunic

consists of ELASTIC and COLLAGEN fibres

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23
Q

What does the Media consist of?

A

Tunica MEDIA = Middle Tunic
THICKEST layer
is often the FUNCTIONAL layer

consists of SMOOTH Muscle, CT and ELASTIC Fibres
the Smooth Muscle allows for VASOCONSTRICTION/DILATION

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24
Q

What does the Intima/Interna consist of?

A

INTIMA =intimate
Tunica INTERNA=Inner Tunic

consists of inner ELASTIC LAMINA which is a THIN SHEET of ELASTIN FIBRES
\+
BASEMENT MEM. for PHYSICAL SUPPORT 
\+
ENDOthelium
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25
What is the change like as you go down the arterial tree?
``` There is a GRADUAL change in histology gradual increase in the properties of the next class of arteries ```
26
What does "arteries of the body" refer to?
Muscular arteries | as muscular arteries are more common and more abundant in the body
27
What is Vasoconstriction?
DECREASE in diameter of arteries
28
What is Vasodilation?
INCREASE in diameter of arteries
29
What control is smooth muscle under?
Sympathetic and Parasympathetic control + under the right conditions sympathetic and parasympathetic is involuntary control
30
What is the function of Arterioles?
Controls blood flow into CAPILLARY BEDS It is the FINAL place of FINE TUNING the blood before it Enters the CAPPILARIES - Last Responsibility for CONTROL and have the CORRECT PRESSURE THIN 10-100microns (HAIR) but have a THICK MUSCULAR wall (HALF the size of the LUMEN), relative to the size of any other blood vessel undergoes the GREATEST PRESSURE DROP and the GREATEST RESISTANCE to flow the Degree of Constriction of arterioles determines the TOTAL PERIPHERAL resistance (over ALL(hence total) arterioles), which IMPACTS the MEAN ARTERIAL blood pressure to decide WHICH capillary network the blood goes to
31
What do arteries often flow beside?
Companion Veins if the Artery Supplies the organ, the Companion Vein will often Drain the Organ (flows are Usually similar)
32
What is the difference between Artery and Vein wall thickness?
Reflects the Influence of PRESSURE
33
What is the size of red blood cells and what do they look like?
Readily Looked for 9 microns Black dots Increase in # of red blood cells = Higher Power
34
What are Arterioles?
Vessels which only have 2-3 layers of smooth muscle
35
What is the Structure of Arterioles?
1-3 layers of circular SMOOTH muscle which is WRAPPED AROUND a vessel in the middle of the tunic lined by ENDOthelial cells
36
What are all Red Blood cells lined with?
Endothelial Cells
37
Which vessel has the thickest walls relative to their size?
Arterioles | wall is 1/2 size of lumen
38
Where are arterioles situated?
between your elastic and muscular arteries
39
What is important about the Mean Arteriol Pressure?
It is important to maintain it within a range 120/80 controlled by arterioles to COARSELY DISTRIBUTE the blood to a certain CAPILLARY NETWORK
40
What determines Mean Arteriol Pressure?
Quantity of blood being pushed into the "cylinder" and Total Peripheral Resisitance
41
What is the size of Capillaries?
very thin the size of RBC(can fit one through)(edges touch therefore capillary) 4-10microns
42
What is the function of capillaries?
Blood flow is SLOW(due to be small) in order to allow TIME for EXCHANGE to occur Capillaries exchange and form (through leakage) with INTERSTITIAL Fluid (interstitial/tissue fluid interacts with cells) capillaries are LEAKY vessels, meaning they have GAPS and PLASMA ESCAPES(so can form tissue fluid) Cannot handle high pressures HYDROSTATIC pressure in capillaries DRIVES fluid OUT most of the LOST Plasma is IMMEDIATELY RECOVERED due to an OSMOTIC GRADIENT-draw back fluid into capillary but not all Need to DRAIN EXCESS fluid form tissues (done by the LYMPHATIC SYSTEM)
43
What is a Capillary?
TINY vessel which is THIN WALLED to allow the EXCHANGE of GASES,NUTRIENTS and WASTES between the BLOOD and the Surrounding TISSUE FLUID (not straight to the cells)
44
What is EDEMA?
When capillary DRAINAGE is IMPAIRED results in SWOLLEN TISSUE filtration > reabsorption MORE FLUID squeezed OUT of capillaries e.g. Lower limbs when Standing too long
45
What is the Structure of Capillaries?
The diameter of a capillary is just Wide Enough to admit 1 RBC Capillary wall is a SINGLE LAYER of ENDOthelium with an EXTERNAL BASEMENT MEMBRANE Capillaries contain NO SMOOTH Muscle, therefore it CANNOT ADJUST its DIAMETER Capillaries also contain NO CT
46
What do capillaries look after?
Interstitial fluid
47
What does interstitial fluid look after?
cells | interstitial fluid = "cell fluid"
48
What cant capillaries tolerate?
High Pressures due to being SO THIN (only one layer of endothelial cells)
49
What is the Function of Venules?
LOW Pressure vessels which DRAIN Capillary Beds During INFLAMMATION and INFECTION, venules are the sites where WBC (=CT cells) LEAVE Blood Circulation to ATTACK Bacteria in the CT
50
What is the Structure of Venules?
a venule is SIMILAR to CAPILLARIES (2-500RBC in diameter)therefore Larger than a Capillary SMALL venule=ENDOthelium and CT LARGE venule = SINGLE layer of SMOOTH Muscle
51
Which vessels of the heart are involved in Exchange?
Elastic Arteries Muscular Arteries Arteriole Capillary
52
Which vessels of the heart are involved in Drainage?
Venule
53
What does drainage involve?
bringing blood back to the heart
54
What does Venule mean?
Little Vein
55
Where are Venules situated?
immediately after capillaries | looks like a large cappilary
56
How are WBC Transported?
WBC use the CARDIOVASCULAR System to be transported around the body. move through the circulatory system when alerted that they are needed they STICK to the WALLS of Venules (able to do this due to the SLOW flow) and then slip through the Endothelial cell wall, through the CT Final goal is to get out into CT
57
What features of vessels benefit exchange?
Capillaries have thin flattened single endothelial cell wall, with the cytoplasm stretched out and reduced to a very thin layer and overlaps neighbouring cells designed to make fluid easy to GET OUT and be exchanged and flow into interstitial fluid outside
58
What does longitudinal mean?
Along the LENGTH of the structure
59
What does a RBC look like when it is damaged in capillaries?
Parachute Mechanical Damage edges are touching edge of capillary but fluid is coming in PUSHING the red blood cell forward and can DESTROY the red blood cells only last a few weeks
60
What happens to damaged RBCs?
spleen and bone marrow recycle
61
What is the benefit of Capillaries only being 1 RBC in diameter?
the RBCs can RUB up again the capillary wall and SLOW it down, allowing MORE TIME for EXCHANGE
62
What does a longitudinal slide of a venule in infection look like?
lots of RBC WBC STICK to the wall will eventually go through and look for the pathogens causing the infection
63
What is the function of veins?
Veins are THIN walled, LOW pressure vessels with a BIG LUMEN which DRAIN blood back into the ATRIA at a SLOW rate Except PORTAL veins which drain blood back into another Capillary Bed A SMALL Change in Venous Blood PRESSURE causes a LARGE change in Venous Blood VOLUME Veins act as a RESERVOIR (doesn't 'store' as blood doesn't 'stop') 64% blood volume = systemic VEINS and VENULES 13% blood volume = systemic ARTERIES and ARTERIOLES
64
What are DVTs?
Deep Vein Thrombosis Thrombi = little blood clots blood stops, This is what happens if you sit in a plane for too long
65
What is the Structure of Veins?
Walls are THING, SOFT and they STRETCH easily (compliant) -if veins need blood they VASOCONSTRICT - push blood from periphery -if veins don't need blood to the heart they VASODILATE Adjust Diameter to change volume of blood Similar structure to Muscular Artery, but with a Much THINNER wall for their size (much less Muscle and CT) LARGER veins (e.g. in legs) have a Large LUMEN and VALVES which Prevent blood flow DEEP veins also have Skeletal Muscle As leg muscles alongside the vein Alternatively contract and relax during walking, the system acts as a Venous Pump, which returns blood right to the atrium
66
What is Vasoconstriction?
what happens when veins NEED blood the vein walls (Muscle Pumps) contract/shorten and thicken/Bulge (soft compliant) which Compresses the blood and pushes the blood towards the heart(atria) "Aided Superiorly" displacing any of the blood above it
67
What is Vasodilation?
what happens when veins DONT need blood Occurs in the veins which are CLOSER to the heart(atria) the veins RELAX, allowing the blood to naturally flow Aids Venous Return
68
What are veins affected by?
Gravity so are us bipedal organisms Hard to push blood from a metre and a half under Low Pressure Leg Veins have an Adaptation they have BICUSPID VALVES Bicuspid valves are found b/w something HARD and a MUSCLE (can be 2x muscles) Muscle Pumps aid venous return
69
What happens if you don't walk enough?
You do not aid venous return to your heart Stare your brain of oxygen = faint need to use your Muscle Pumps
70
Why do people get Varicose Veins?
Typically Elderly get Varicose veins on their Legs Common in Lower Limb's Superficial veins and in Oesophagus Veins have STRETCHED so much that the valves no longer meet, and therefore Wont Function properly, and blood POOLS Leaky venous valves(weakened) allow backflow of blood, which causes pooling of blood,creates pressure that distends the vein, allows fluid to leak into surrounding tissue (inflamed and tender), blood doesn't reach brain (faintness), veins become Dilated and Twisted. Cause: Congenital, Mechanical Stretch due to Prolonged Standing/Ageing some young people get it Itchy and Painful Can be Cut out/Laser Treatments/Chemicals
71
What is the function of Coronary Arteries?
Supply the heart (Myocardium) with Oxygenated blood, as the heart needs its own supply Coronary arteries attach at the coronary Atria and exits the ascending aorta just above the aortic valve leaflets on the Outside and send Branches into the myocardium Forms a Crown around the top of the heart Match Stick Thickness Common Muscular Arteries Coronary arteries are critically important because of the tissues they supply (muscle is a very active organ, always contracting) Get the Best Blood(O2 rich) and Best (Highest) Pressure First branch of the aorta are the RH and LH Coronary arteries Deoxygenated blood is drained from the myocardium by Cardiac Veins or Coronary Arteries, which return the blood to the Right atrium (no clinical importance) 1/3 of population have problems
72
Where does the Left Coronary Artery supply blood?
Left side of the Heart | Front side of the heart
73
Where does the Right Coronary Artery supply blood?
Right side of the Heart | Posterior side of the heart
74
Is the Brachiocephalic branch the first branch off the aorta?
No | technically it is the coronary arteries
75
Why are coronary artery branches needed?
Because the walls of the myocardium are too thick for oxygen to diffuse from the cappilaries
76
How is deoxygenate blood drained from the myocardium?
Cardiac Veins | back to the Right side of the heart
77
What is Atherosclerosis?
Wall of the Elastic artery become LESS COMPLIANT (stiff) so there is Less Energy stored in the stiffer arteries during Systole Leads to CLOGGING,NARROWING and HARDENING of arteries Occurs in Large Branches on the SURFACE of the heart Fatty Plaque inside walls of vessels -Narrows the Lumen of vessels, therefore Less Space for blood to flow Blockage upstream affects many downstream branches the Heart must Pump Harder to Maintain same blood flow If a coronary artery is narrowed by 20% of normal cross section by ATHEROMA a significant obstruction to blood flow occurs Myocardial Infarction/heart attach is when there is Not enough O2 delivered to heart, leading to Death of the Heart Wall During exercise the myocardium supplied by a diseased artery runs low on O2 (ISCHEMIA) causing chest pain (ANGINA)(SNS to T1-T5 (arm,nipple,chest)) Sever ANGINA=death/Infarction of local area of myocardium Sometime ANASTOMOSES (artery-artery junctions) between Small Penetrating branches of main coronary arteries WIDEN slowly so the Ischaemic area can be supplied with oxygenated blood from a Distant Artery. More prevalent the older you get
78
What is Ischemia?
"Without oxygen" Inadequate blood supply to an organ or part of the body, especially the heart muscle run out of O2 supply
79
What is Angina?
severe chest pain and down arm (deferred pain)
80
Where is the sympathetic nerve supply?
T1-T5
81
Why does the heart wall look so?
Juicy and Red because it is Rich in blood supply(lots of capillaries) Aerobic Organ
82
What is the danger of having a thrombus?
can Not know you have a thrombus (blood clot) Grow Break free and enter circulatory system comes across an area of coronary artery which is narrowed can Block the artery can result in an instantaneous effect of low O2 supply to having No O2 supply at all
83
What does a survived myocardial infarction tissue look like?
white and scarred | developed collagen fibres and scarred over
84
What can cause you to have sequential myocardial infarctions?
No change in Diet or Lifestyle

MedSci142 (20 decks)

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