Lab 4 Prelab Flashcards
1
Q
Define auscultation.
A
Listening for body sounds
2
Q
Describe the flow of de-oxygenated blood through the circulatory system.
A
- De-oxygenated blood from the systemic circulation enters the RA
- Blood is pumped to the pulmonary circulation via the RV
3
Q
Describe the flow of oxygenated blood through the circulatory system.
A
- Blood from RV pumps blood into lungs where gas exchange occurs
- Oxygenated blood re-enters the heart at the LA
- Blood is pumped out of the systemic circulation by the LV
4
Q
What kind of walls do the aorta and the biggest arteries have? Characteristics?
A
Thick muscular walls w/ many elastic fibers to flex and rebound pressure waves
5
Q
What happens as artery size reduces to arterioles?
A
Elastic component reduces, then muscle wall thins
6
Q
What size arteries and arterioles are contractile? What does this affect?
A
Medium arteries and arterioles are contractile and affect resistance
7
Q
List the 3 vascular tissue layers.
A
- Tunica intima
- Tunica media
- Tunica adventitia
8
Q
What are capillaries? Location? Function?
A
- An endothelial layer on a basal lamina
- Site of exchange b/t venous and arterial system
9
Q
What are the characteristics of venules and veins? What actively changes its diameter?
A
- Thin walled
- Larger lumen compared to wall diameter
- One way valves limit direction of flow
- Smooth muscle actively changes diameter
10
Q
What dictates blood flow?
A
Differences in pressure
11
Q
Where does friction from blood flow occur? What does this cause?
A
- B/t blood and vessel walls
- Causes vessels to resist fluid movement
12
Q
What does vascular resistance measure?
A
How hard it is for blood to flow through a vessel
13
Q
What is the equation for blood flow?
A
Q = ΔP/R
- Q = flow rate (vol/time)
- ΔP = pressure diff (mmHg)
- R = resistance (mmHg x time/vol)
14
Q
In the blood flow equation, which variable is regulated? Which changes?
A
- P is regulated (constant)
- R changes to alter flow rate
15
Q
What is the restistance equation?
A
R = 8Lη/πr4
- L = length of vessel
- η (eta) = fluid viscocity
- r = radius of vessel
Small Δr = big ΔR
16
Q
What is Poiseuille’s equation?
A
Q = ΔPπr4/8Lη
- Combines resistance equation w/ blood flow equation
17
Q
According to Poiseuille’s equation, what is flow rate primarily regulated by?
A
Changes in the radius of a vessel (vasoconstriction or vasodilation)
18
Q
What is pressure in the blood vessel determined by?
A
- Volume of blood in the vessel
- Compliance of the vessel
19
Q
Define compliance.
A
How easily a blood vessel can be stretched
20
Q
What is the equation for compliance?
A
C = ΔV/ ΔP
21
Q
Are veins or arteries more compliant?
A
Veins
22
Q
Define capacitance.
A
Holding capacity
23
Q
How are compliance and capacitance related?
A
Vessels w/ a high compliance also have a high capacitance
24
Q
What kind of arterial-venous pressure gradient does the heart work towards?
A
Keep arterial pressure higher than venous pressure
25
What % of blood is in the arteries? Veins?
* 10-20% in arteries
* 70% in veins
26
Define cardiac output.
Volume of blood pumped by each of the ventricles per min
27
Equation for cardiac output.
CO = HR x SV
28
What changes in flow will cause vessel volume to increase?
* Increased inflow
* Decreased outflow
29
How could you get an increase in volume in the arteries?
Increase in SV, CO, HR or increase in arterial resistance
30
How would you get an increase in volume in the veins?
* Decrease in right heart pumping
* Change in body position from reclining to upright
31
What changes in flow will cause venous volume to decrease?
* Decreasing inflow
* Increasing outflow
* Increased SV, HR due to increased contractility
* Increased arterial resistance
32
What is a sphygmomanometer?
BP cuff
33
What is sphygmomanometry by auscultation?
Taking a BP by listening for artery sounds
34
What are Korotkoff sounds?
Tapping sounds that a partially occluded artery makes due to turbulent blood flow
35
What is systolic BP?
* Pressure where the 1st Korotkoff sounds are heard
* Peak pressure generated by artery
36
What is diastolic BP?
Pressure where Korotkoff counds are no longer heard
37
What is arterial pressure a function of? Why?
Change in volume since its capacitance is fairly constant
38
When does an increase in volume in the arteries occur? What does this cause?
When blood is ejected from the ventricles during systole
* Causes arteries to distend (swell) slightly
* Increase in pressure
39
What fraction of the blood in arteries flows out during systole?
1/3
40
What happens to the arteries during diastole?
Arteries passively recoil due to their elastic properties --\> pushes more blood out
41
What allows blood flow to the capillaries to be constant?
Continued pulsatile blood flow out of the arteries during diastole
42
Define MAP.
Avg effective pressure that drives blood through the systemic organs
43
What is the equation for MAP?
MAP = CO x TPR
44
Define TPR.
Overall resistance to flow through the entire systemic circulation
45
How is MAP approximated? (equation)
MAP = 1/3 SBP + 2/3 DBP
46
Equation for pulse pressure.
PP = SBP - DBP
47
What is a normal human BP?
120/80 mmHg
48
What is the effect of gravity on BP?
Gravity produces a hydrostatic pressure diff b/t 2 pts of different height
49
How does a supine position affect BP?
* Whole body is at heart level and becomes equal
* No added hydrostatis pressure
* Lower BP
50
How does a standing position affect BP?
* Hydrostatic pressure is added to area below heart and substracted from areas above heart
* Higher BP
51
When standing, where in the body does the vasculature have higher pressure?
Vasculature around feet have higher P than vasculature near head
52
When you move rapidly from supine to standing, gravity causes the blood to pool in what direction? Why? What does this cause?
* Downward
* Caused by decreases in VR, HR, CO, arterial blood pressrue
* Can cause inadequate cerebral blood flow, resulting in dizziness
53
What are baroreceptors? Location? Function?
* Specialized mechanoreceptors that detect stretch --\> send afferents to the brain
* Found in the carotid sinus and aortic arch
54
How does sympathetic innervation affect the arteries?
Vasoconstrict arteries (decrease in diameter) --\> increase in resistance --\> decrease in blood flow to venous side
55
How does sympathetic innervation affect the veins?
Decrease in diameter --\> decrease in capacitance --\> increase in pressure --\> increase in blood flow and venous return
56
What does the sympathetic NS do w/ regards to the CV system? What receptors to their bind to? What does this cause?
* Sympathetic nerves release norepinephrine, which binds to alpha 1 adrenergic receptors on smooth muscle cells in the vessel walls --\> cause vasoconstriction
* Sympathetic afferents to the heart release norepinephrine, which bind to β-adrenergic receptors --\> cause increase in HR and contractility (SV, CO)
57
What do parasympathetic nerves do w/ regards to the CV system? What do they bind to? What do they release? What does this cause?
* Parasympathetic efferents to the heart release ACh and bind to muscarinic AChR --\> causes vasodilation and a decrease in HR and contractility (SV, CO)
58
How does the autonomic NS respond to an increase in BP? What is the result?
* Increase firing rate of baroreceptors
* Decrease sympathetic
* Increase parasympathetic (↓HR → ↓CO → ↓BP)
* Certain vessels: ↑vasodilation → ↓resistance → ↓BP
59
How does the autonomic NS respond to a decrease in BP? What is the result?
* Decrease firing rate of baroreceptors
* Decrease parasympathetic
* Increase sympathetic (↑HR → ↑CO → ↑BP)
* ↑contraction → ↑SV
* Arterioles: ↑vasoconstriction → ↑resistance → ↑BP
* Veins: ↑vasoconstriction → ↑VR → ↑SV → ↑CO → ↑BP
60
What is reactive hyperemia? Result? Example?
* Reaction to a decrease in blood flow to a tissue w/ no change in the tissue's metabolism
* Result: transient higher than normal blood flow after removal of the decrease/restriction
* Ex) when your foot "falls asleep" then "wakes up"
61
What is the mechanism by which reactive hyperemia occurs?
* Build up of local metabolites that would normally be swept away by blood flow
* Elevated metabolic concentration activates vasodilatory pathways
62
What is active hyperemia? Mechanism?
* Increased blood flow caused by an incraese in metabolic activity, such as exercise
* Mechanism: release of metabolites cause vasodilation and increase in blood flow
63
What are the CV system's responses to exercise?
* Increase in SNS activity at the onset of exercise --\> increases HR and CO --\> increases MAP
* Increase in SNS activity to decrease blood flow to inactive muscles, renal, and splanchnic (gut) circulations
* Active skeletal muscle releases metabolites --\> causes vasodilation, decreases TPR, increases blood flow
* Skeletal muscle pump increases venous return to sustain CO
64
What does the diving reflex allow?
Allows prolonged submersion by limiting the rate of O2 use and directing blood flow to essential organs
65
What is the mechanism by which the diving reflex occurs?
* Bradycardia caused by increased vagal activity
* Vasoconstriction at non-essential organs caused by increased general SNS activity
66
On an ECG, what does the P wave represent?
Depolarization of atria
67
On an ECG, what does the QRS wave represent?
Depolarization of ventricles
68
On an ECG, what does the T wave represent?
Repolarization of ventricles
69
What is the relation b/t HR and the RR interval
Inversely proportional
70
What is the RR interval?
Interval b/t 2 R wave peaks
