Unit 1. Lec 2-Biomechanical Properties of Blood Vessels Flashcards
(93 cards)
1
Q
What are the three main layers of the blood vessel wall?
A
- Tunica Intima
- Tunica Media
- Tunica Adventitia
2
Q
What component is found in each layer of the blood vessel wall?
A
Elastic membrane: Elastin
3
Q
What is present in the Tunica Intima?
A
- Monolayer of Endothelial cells
4
Q
What is present in tunica media? (5)
A
- Smooth muscle cells (SMC)
- Collagen
- Elastin
- Proteoglycans
- Glycosaminoglycan
5
Q
What is present in tunica adventita? (5)
A
- Fibroblast
- Collagens
- Elastins
- Proteoglycans
- Glycosaninoglycan
6
Q
What is the composition of large arteries?
A
Thick media layer and higher elastin
7
Q
What is the composition of small arteries?
A
Amount of elastin decreases, contains more SMCs
8
Q
What is the composition of veins?
A
Thinner media layer and less amount of elastic tissue (elastin barely present)
9
Q
List the vessel type and their relative size (diameter)
A
- Aorta:25 mm
- Large Arteries:1.0-4.0 mm
- Small Arteries: 0.2-1.0 mm
- Arterioles: 0.01-0.20 mm
- Capillaries: 0.006-0.010 mm
- Venules: 0.01-0.20 mm
- Veins: 0.2-5.50 mm
- Vena Cava: 35 mm
10
Q
Which vessels have the function of distribution?
A
- Aorta: Pulse dampening and distribution
- Large Arteries: Distribution of arterial blood
- Small Arteries: Distribution and resistance
11
Q
Which vessels have the function of resistance?
A
- Small Arteries: Distribution and resistance
- Arterioles: Resistance (pressure + flow regulation)
12
Q
Which vessels have the function of exchange?
A
- Capillaries: Exchange
- Venules: Exchange, collection, and capacitance
13
Q
Which vessels have the function of capacitance?
A
- Veins: Capacitance function (blood flow)
- Vena cava: collection of venous blood
14
Q
What tissues (4) make up the vessels walls?
A
- Endothelium
- Elastic tissue
- Smooth muscle
- Fibrous tissue
15
Q
All vessels type have endothelium except?
A
NONE, all vessel types contain endothelium
16
Q
All vessel types have elastic tissue except?
A
Capillaries and Venules
17
Q
All vessel types have smooth muscle except?
A
Capillaries and venules
18
Q
All vessel types have fibrous tissues except?
A
Capillary
19
Q
List the steps of the Cardaic cycle
A
- Venous return to the right atrium (Systemic circuit)
- Venous flow arrives in the right ventricle (Diastole)
- Venous blood is sent in the lung via the pulmonary artery (Pulmonary circuit)
- Affter oxygenation in the lung the blood (red blood) returns to the left atrium
- Red blood arrives in left ventricle
- Red blood is sent in the arteries to the tissues
20
Q
Explain the numbered points in the photo
A
1.AV valve is open: Left heart is in diatole b/c ventricles are filling up w/ blood, low pressure in LA +LV
2.Aortic valve closes: Ventricle is filled with blood (still in diastole)
3.Aortic valve opens: Contracts blood out of LV into the Aorta, now in systole, High pressure in LV + aorta
4.AV valve closes: Blood exits aorta, back to diastole, low pressure
21
Q
Define Diastolic pressure (DBP), Pd
BP Parameters (Large Arteries)
A
the lowest arterial pressure measured during a cardiac cycle
22
Q
Define systolic pressure (SBP), Ps
BP Parameters (Large Arteries)
A
the highest arterial pressure measured during a cardiac cycle
23
Q
Define pulse blood pressure (PBP or PP)
BP Parameters (Large Arteries)
A
The differences btw systolic pressure and diastolic pressure (Ps-Pd). If all other factors are equal, the magnitude of PB reflects the volume of blood ejected from the LV in a single beat.
24
Q
Define Mean blood pressure (MBP)
A
- Pa: the average pressure during a complete cardiac cycle. Dependent in diastolic pressure, Pd
- Approx. by: Pa=Pd + 0.33(Ps-Pd)
25
Define Mean blood pressure (MBP)
* Pa: the average pressure during a complete cardiac cycle. Dependent in diastolic pressure, Pd
* Approx. by: **Pa=Pd + 0.33(Ps-Pd) or Pa=Pd+1/3 PP**
26
What are 3 ways that you can measure blood pressure?
* Blood flow pattern (Laminar vs turbulent flow)
* Arterial vibration (Oscillometry method)
* Korotoff Sound
27
How is blood pressure measured? (3)
* Blood flow pattern (Laminar vs turbulent flow)
* Arterial vibration (Oscillometry method)
* Korotoff Sound
## Footnote
Arteries are the source of measurements
28
Explain the outcomes of laminar vs turbulent flow in arteries
* Laminar flow: produce little vibration of the arterial wall, and no sounds
* Turbulent flow: Artery is partially constricted, causing the artery to vibrate and produce sound
29
What is the tapping sound associated with the turbulent flow of a partially constricted atery called?
Korotkoff sounds
30
What are two methods used to measure BP?
1. The Oscillometry Method
2. The Ausculation Method
31
Explain the Oscillometry method
* Oscillometry method is based on arterial wall vibration.
* Turbulent blood flow will occur when the cuff pressure is greater than the diastolic pressure and less than the systolic pressure
32
Explain the Ausculation Method
The Ausculation Method is based on the Korotkoff sound
33
List the physiologic factors that are determinants of Arterial Blood Pressure
* Cardiac output (Q): heart rate*stroke volume
* Peripheral Resistance (R)
34
Explain stroke volume (SV)
Is the volume of blood pumped out from the left ventricle per beat
35
Explain Cardiac Output
* Describes the volume of blood being pumped out of the heart, by the left or right ventricle per unit time
* Equals to SV x heart rate (HR)
36
What is the equation that explains the relationship btw arterial bp, cardic output and resistance?
∆P=QR
37
What occurs to listed parameters when stroke volume is increased, and no change in HR and R?
* Systolic BP
* Diastolic BP
* Mean BP
* Pulse pressure
* Ps increases after every cardiac cycle
* Pd increase after every cardiac cycle
* Mean BP increase b/c Pd increases due to accumulating blood volume (MBP=Pd + 1/3PP)
* PP stays the same b/c Ps and Pd increase by the same amount, so the blood volume stays the same
## Footnote
Baseline increase b/c blood volume starts to accumulate after each cardiac cycle
38
What occurs to listed parameters when stroke volume is decreased, and no change in HR and R?
* Systolic BP
* Diastolic BP
* Mean BP
* Pulse pressure
* Ps decreases after every cardiac cycle
* Pd decreases after every cardiac cycle
* Mean BP decreases b/c Pd decreases due to accumulating blood volume (MBP=Pd + 1/3PP)
* PP stays the same b/c Ps and Pd decrease by the same amount, so the blood volume stays the same
39
What occurs to listed parameters when Heart rate is increased, and no change in SV and R?
* Systolic BP
* Diastolic BP
* Mean BP
* Pulse pressure
* Ps increases b/c Pd increases
* Pd increases b/c HR increases which causes less time for blood to flow from the aorta to vasculature accumulating more blood in the aorta
* MBP increases b/c Pd increases
* PP stays the same b/c no change in the SV (LV to aorta per beat)
40
What occurs to listed parameters when Heart rate is decreased, and no change in SV and R?
* Systolic BP
* Diastolic BP
* Mean BP
* Pulse pressure
* Ps decreases b/c Pd decreases
* Pd decreases b/c HR decreases which causes more time for blood to flow from the aorta to vasculature accumulating less blood in the aorta
* MBP decreases b/c Pd decreases
* PP stays the same b/c no change in the SV (LV to aorta per beat)
41
What occurs to listed parameters when total peripheral resistance is increased, and no change in HR and SV?
* Systolic BP
* Diastolic BP
* Mean BP
* Pulse pressure
* Ps and Pd increases d/t TPR increasing making it harder for blood to flow from aorta to vasculatures which causes accumulation
* MBP increase d/t Pd increasing
* PP does not change b/c there is no change in SV
42
What occurs to listed parameters when total peripheral resistance is decreased, and no change in HR and SV?
* Systolic BP
* Diastolic BP
* Mean BP
* Pulse pressure
* Ps and Pd decreases d/t TPR decreasing making it easier for blood to flow from aorta to vasculatures
* MBP decrease d/t Pd decreasing
* PP does not change b/c there is no change in SV
43
What factors (3) affect vascular resistance?
* Resistance is determined by:
1. Length
2. Viscosity
3. Radius
* Equation: Equation: R≅ήL / r4
44
How does vessel length affect resistance?
A vessel have twice the length of another vessel (each having the same diameter) will have twice the resistance to flow
45
How does blood viscosity affect resistance?
If the viscosity of the blood increases 2-fold, the resistance to flow will increase 2-folds
46
How does radius affect resistance?
An increase in radius reduces resistance. The change in diameter alters resistance to the fourth power of the change in diameter
## Footnote
Ex. a 2-fold decrease in diameter increases resistance by 16-fold, therefore the bloos flow (from 100% to 6.25%)
47
What affects resistance the most; length, viscosity or radius?
* Vessel resistance is very sensitive to changes in radius (diameter), therefore blood flow (major BP regulation point)
* Length and viscosity are generally considered constant
48
Explain the Cross-secctional area, radius, resistance and blood pressure of the Aorta and Large Arteries
* Lowest cross-sectional area
* Lowest radius
* HIghest resistance
* Highest blood presssure
49
Explain the Cross-sectional area, radius, resistance and blood pressure from the arteries to arterioles
* The cross-sectional area (total radius) is gradually increased
* Dramatically decreasing resistance and blood pressure
50
Define Vascular Tone
The degree of constriction experienced by a blood vessel relative to its maximally dilated state
51
What does all arterial and venous vessels under basal (basic) conditions exhibit?
Some degree of smooth muscle contraction that determines the diameter (hence tone of the vessel)
52
Basal vascular tone differs among organs:
______ in myocardium, skeletal muscle & skin
______in the brain and kidney
High
Low
53
How is vascular tone determined and seperated?
* Determined by the balance of competing vasoconstrictor and vasodilator
* Seperated into extrinisic factors and intrinstic factors
54
What is regulated and how by the extrinsic factors of vascular tone?
* Regulate arterial blood pressure by altering systemic vascular resistance
* Are from outside the tissue
## Footnote
E.g.-Extrinsic factors on the Arteriole: Neural & Humoral
55
What are the roles of the intrinsic factors of vascular tone?
* Important for local blood flow regulation within the organ
## Footnote
e.g. Intrinsic fators of the Arteriole: Tissue Metabolites, Local hormones, myogenic, endothelial factors
56
Define Vascular Stenosis
"Stenosis" refers to an abnormal narrowing (decreasing vessel diameter) of an artery, partially obstructs blood flow
57
Which vessel types does stenosis most commonly occur in?
Large distributing arteries such as coronary, renal, cerebral, iliac and femoral arteries
58
What causes Stenosis (the narrowing)?
From a chronic disease process such as atherosclerosis
59
What causes acute stenosis?
Focal Vasospasm
60
Stenosis _____________ vascular resistance
increases
61
What occurs to cause critical stenosis?
Critical narrowing of an artery that results in a significant reduction in maximal flow capacity in a distal vascular bed. Typically, a 60-75% reduction in the diameter of the large distrbuting artery
62
List the physical factors that are determinants of Arterial Blood Supply
* Arterial blood volume
* Arterial compliance
63
What is vessel compliance (C)?
The ability of a vessel to distend and increase volume with increasing transmural pressure
## Footnote
Transmural pressure: pressure on the inside is higher than pressure on the outside
64
What is vessel compliance (C)?
The ability of a vessel to distend and increase volume with increasing transmural pressure
## Footnote
Transmural pressure: pressure on the inside is higher than pressure on the outside
65
How is vessel compliance (C) quantified?
* The change in volume (𝚫v) divided by the change in pressure (𝚫P)
* Equation: C=𝚫V/𝚫P
66
If you have a high change in pressure, but a low change in volume do you have a lower or higher compliace?
Lower compliance
67
What is an important function of large arteries and veins?
The ability of a blood vessel wall to expand and contract passively with changes in pressure
68
The volume that stretches the wall is called ________ and the rest is called _______.
Streesed volume, unstressed volume
69
Ca (arterial compliance) is highest when?
* Within normal physiological pressure range (75-125 mmHg)
* It responds very well to change in pressure.
* Like a ballon, Ca is low at both high and low Pa (i.e 𝚫Va versus 𝚫Pa is sigmoidal)
## Footnote
You can also tell based on this picture, the slope of this curve within this range is high.
70
What is the equation for arterial elastance?
Ea= 𝚫Pa/𝚫Va
71
When COMPARING Arteries to veins
ARTERIES have
Lower or higher elastance?
Lower or higher compliance?
* Higher elastance (d/t higher elastin levels)
* Lower compliance
## Footnote
ALSO HAS MORE SMOOTH MUSCLE CELLS COMPARED TO VEINS
72
What does elastic tissue do for blood vessels?
Enables a blood vessel to expand and contract passively w/ changes in pressure
73
When COMPARING Arteries to veins
VEINS have
Lower or higher elastance?
Lower or higher compliance?
* Lower elastance
* Higher compliance
## Footnote
Less smooth muscled too, this is important b/c veins can expand very quickly and easily which is good for blood storage.
74
Explain the Windkissel Effect in simple terms
## Footnote
Arterial Compliance (elasticity)
* Blood flow from heart to elastic arteries.
* Elastic arteries can expand and act as pressure reservoirs. This allows for continous blood flow
75
Since the rate of blood entering the elastic arteries exceeds that leaving them to peripheral tissue, there is a net storage of blood in the arteries during ____ , which discharges during ____ to keep the blood flow continue.
Systole, diastole
76
The aorta and large arteries act as a “pressure reservoir” (windkissel vessels), allowing what three things?
1. Continous blood flow to peripheral vessels
2. Reduce workload on heart (b/c with recoil it pushes remainder of blood to capillaries)
3. Reduce blood pressure fluctation "aka dampening"
## Footnote
The ability to expand and recoil is needed to continue to push blood in body and regulate pressure
77
Explain artherosclerosis in terms of what happens with the arteries
* The arterteries are stiff so they cannot expand or contract very well (basically no diameter changes) so we higher blood pressure occuring.
* This happens to a lot of older people
* No dampening or windkiksself effect
77
Explain artherosclerosis in terms of what happens with the arteries
* The arterteries are stiff so they cannot expand or contract very well (basically no diameter changes) so we higher blood pressure occuring.
* This happens to a lot of older people
* No dampening or windkiksself effect
78
As we age we see
____ compliance
____ stiffening
____ systolic BP
____ pulse pressure
* lower
* higher
* higher
* higher
79
With arterial stiffness we see
____ collagen
____ elastin
* higher
* lower
(remember that elastin is the most important for expansion ability: The elastic tissue enables a blood vessel to expand and contract passively with changes in pressure)
80
List some causes of arterial stiffness (5)
* **Endothelial cells** : Endothelial dysfunction, increased permeability
* **Extrinsic Influences**: NaCl, lipids, angiotensin, sympathetic neurohormones, shear stress, increased luminal diameter
* **Intima**: Increased collagen, AGE's, leukocytes, I-CAM, MMP, VSMC; Decreased Elastin
* **Media**: Increased VSMC, collagen, AGE's, MMP; Decreased Elastin
* **Adventita**: Increased collagen, fibroblasts
81
What are 4 physiologcal properties of veins?
1. High Compliance
2. Low Resistance
3. Blood reservoir system ( has 60-70% of total blood volume)
4. Venous valves have one-way flow towards the right heart
82
What are 5 ways veins can return blood to the heart?
1. Pressure gradient
2. Skeletal muscle pump with venous valves
3. Respiratory pump
4. Regulated sympathetic vasocostriction
5. Cardiac suction effect
83
Explain how veins can push the blood back to the heart with pressure gradient
* LV & Aorta has a HIGH pressure of around 120 and the pressure gradient is pushing blood back towards the heart we see LOW pressure of 0 at the right atrium
* Veins to the heart have lower blood pressure than the arteries. Gradient from 120 mmHg-->15 mmHg-->0 mmHg
## Footnote
Think passive diffusion
84
Explain how veins can push the blood back to the heart with skeletal muscle pump (with venous valves)?
1. A major mechanism promoting venous return during normal locomotory activity (e.g. walking, running), the muscle pump system
2. Peripheral veins, particularly in the legs and arms, have one-way valves that direct flow away from the limb and toward the heart
3. Veins physically located within large muscle groups undergo compression as the muscles surrounding them contract, and thet become decompressed as the muscles relax.
85
Explain how veins can push the blood back to the heart with respiratory pump.
WITH INHALATION we see
diaphragm ____
Blood pressure in abdominal cavity ____
Blood moves ____
thoracic cavity ____
pressure in pleural cavity ____
Increase blood flow into ____
* Diaphragm **contracts**
* Blood pressure in abdominal cavity **increases**
* Blood moves **superiorly**
* Thoracic cavity **expands**
* Pressure in pleural cavity **decreases**
* Increases blood flow into **thoracic veins**
## Footnote
Pulls blood from smaller veins in abdominal cavity into IVC and RA
86
Explain how veins can push the blood back to the heart with respiratory pump.
WITH EXHALATION we see
diaphragm ____
Blood pressure in abdominal cavity ____
thoracic cavity ____
pressure in pleural cavity ____
Increase blood flow into ____
Diaphragm **expands/relaxes**
Blood pressure in abdominal cavity **decreases**
Thoracic cavity **increases**
Pressure in pleural cavity **increases**
Increase blood flow into **heart and abdominal veins**
## Footnote
Pushes blood into RA
87
Explain how veins can push the blood back to the heart with regulated sympathetic vasoconstruction
With increased sympathetic stimulation you get:
Vasoconstriction
Increase venous pressure
Increase venous return
Increase EDV (end diastolic volume; the amt of blood about to be pumped out)
## Footnote
"Fight or Flight"
88
Explain how veins can push the blood back to the heart with the cardiac suction effect
1. Heart plays role in its own filing. During venticular contraction, AV valves are pulled downward enlarging artial cavities.
2. Atrial pressure drops below 0 mmHg and increases venous returns
## Footnote
Pulling down on atria--> increases atrial volume--> decreases artial pressure which drives blood atria
89
All of the following are physiological determinants of arterial blood pressure except:
a. Heart rate
b. Stroke volume
c. Arterial blood volume
d Peripheral resistance
c. Arterial blood volume
90
Assuming no changes in heart rate or resistance, what are the effects of decreasing stroke volume?
a. Increase in mean blood pressure (MBP)
b. Initial decrease in pulse pressure
c. No initial change in pulse pressure
d. Increased accumulation of blood volume
b. Initial decrease in pulse pressure
91
As blood vessel diameter increases:
a. Collagen composition within the tunica adventitia decreases
b. Elastin composition in the tunica media decreases
c. Smooth muscle cell composition in the tunica media decreases
d. Elastin composition in the tunica adventitia decreases
c. Smooth muscle cell composition in the tunica media decreases
92
What is the mean blood pressure for a student with a systolic pressure of 125 mmHg and diastolic pressure of 95 mmHg?
a. 105 mmHg
b. 110 mmHg
c. 125 mmHg
d. 73 mmHg
a. 105 mmHg
