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Medsci 142 > 03 Cardiac > Flashcards

03 Cardiac Flashcards

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1
Q

How much blood does the systemic circuit carry?

A

85%

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2
Q

Compare the systemic and pulmonary circuit in terms of oxygenated and deoxygenated blood and where these are carried

A

systemic circuit - veins carry deoxygenated blood and arteries carry oxygenated blood

pulmonary circuit - veins carry oxygenated blood and arteries carry deoxygenated blood

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3
Q

Describe the linked pathway between the systemic and pulmonary circuit in terms of deoxygenated blood to oxygenated blood

A

deoxygenated blood: enters the superior and inferior vena cavae from the systemic circuit, enters the right atrium, flows through the tricuspid valve to the right ventricle. From the right ventricle it enters the pulmonary trunk via the pulmonary valve and is transported to the lungs via the pulmonary arteries. Goes to the lungs and is reoxygenated

oxygenated blood: flows from the lungs to via pulmonary veins to the left atria. Oxygenated blood enters the left ventricle via the mitral valve. it exits through the aortic valve into the aorta where it is then transported around the systemic circuit.

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4
Q

Explain why the systemic circuit sees a greater drop in pressure than the pulmonary circuit

A

Blood travels further around in the systemic circuit, losing some of the pressure compared to the short pulmonary circuit where blood retains most of its pressure.

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5
Q

What is the function of the systemic circuit?

A

To supply the body’s various organs systems with oxygenated blood

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6
Q

What is the function of the pulmonary circuit?

A

To ensure blood is re-oxygenated i.e. gas exchange

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7
Q

What are the similarities between the systemic and pulmonary circuit?

A

Both require the heart to push blood through the vessels, both contain arteries and veins the heart and both circuits carry oxygenated and deoxygenated blood

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8
Q

What is special about veins in the systemic system?

A
  • They can act as a blood reservoir
  • Can distend to help store blood and transport deoxygenated blood back to the heart for oxygenation via the pulmonary circuit.
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9
Q

What pressure must the systemic circuit maintain to overcome the high systemic resistance?

A

between 120 and 80 mmHg

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10
Q

Why does the pulmonary circuit need less pressure to deliver blood? What pressure must it maintain?

A

Due to the proximity of the lungs to the heart.
27 mmHg

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11
Q

What is unusual about the venous drainage of the gut

A

Venous drainage from the gut carries deoxygenated, nutrient rich blood to the liver via the hepatic portal vein. the liver also receives deoxygenated blood from seperate systemic artery (dual blood supply)

Blood leaving the gut does not go directly back to the heart (as is the norm in the systemic circuit)

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12
Q

Name the great vessels of the heart and label them on a diagram

A

Superior vena cava, Inferior vena cava, Aorta, Pulmonary trunk and the pulmonary veins

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13
Q

Name the chambers of the heart and label them on a diagram

A

Right atrium, Right ventricle, Left atrium, Left ventricle

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14
Q

What class of valves does the aortic valve belong to? Describe its shape and when these valves are open or closed

A

It belongs to a class known as semilunar valves and has three half-moon shaped cusps which are closed during ventricular filling and open during ventricular ejection

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15
Q

What is the name given to inlet valves

A

atrioventricular valves

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16
Q

What are the two atrioventricular called and where are they located?

A

Mitral valve: between the left atrium and left ventricle
Tricuspid valve: between the right atrium and right ventricle

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17
Q

Describe the pressure change from the blood flow in the atria to the ventricle. Explain how the valves function in this process

A

After atrial contraction, the pressure between the ventricles and the atria are equal.
when the ventricle contracts, the pressure in the ventricle increases. Once the pressure in the ventricles is higher than the atria, blood starts to be pushed through the valve.
Blood fills the valve flaps from underneath. The edge flaps meet in the middle to prevent back flow into the atrium.
The chordae tendineae act as strings preventing the valves inverting

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18
Q

What is isovolumetric contraction? What state are the valves in during this stage?

A

causes the left ventricular pressure to rise above atrial pressure.

Outlet valves are closed as the pressure is higher in the arteries than that of the ventricles. Once the pressure in the ventricles is higher than the pressure of the arteries, the valves are forces open and ejection of blood occurs

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19
Q

What occurs to pressure and blood flow during ventricular relaxation

A

The pressure decreases and once the pressure of the arteries is greater than that of the ventricles, blood flows back into the ventricles. When it does so it fills up the semi-lunar valves. the valve flaps are forced together and create a seal preventing blood from returning to the ventricles

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20
Q

Explain what the chordae tendineae and papillary muscles are, where they are located and how they function

A

fibrous connective tissue
papillary muscles are muscles located in the ventricles of the heart.
They attach to the cusps of the atrioventricular valves (mitral and tricuspid valves) via the chordae tendineae function to stop blood from flowing back to the atria upon ejection

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21
Q

Explain how blood and the chordae tendineae/papillary muscles work together to stop blood flow back into the atria

A

when the ventricle squeezes blood out from the area of high pressure to low pressure, blood will try to flow back to the low pressure atria. The blood will go underneath the valve cusps trying to push back into the atria. This is when the chords and papillary muscles are under enough tension to cause the flaps to meet and prevent backflow.

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22
Q

Why are the tricuspid and Mitral opening of the ventricles larger than the aortic and pulmonary opening?

A

The inlets must be large to admit blood at low pressure
The outlets are small diameter because blood leaves the ventricles at high pressure.

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23
Q

What is the ratio of peak pressure and wall thickness of LV to RV

A

5:1
(LV= 120 mmHg, RV=27 mmHg)

3:1

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24
Q

What are the names for inlet and outlet valves and describe how they differ in anatomy

A

inlet - atrioventricular (mitral and tricuspid, cusps are flat flaps with free edges restrained by chords)
outlet - semilunar (aortic and pulmonary, three cusps, lack chords)

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25
The apex of the heart points in what directions?
inferiorly and anteriorly to the left
26
How much of the hearts mass lies to the right and left of the heart respectively?
right - 1/3 left -2/3
27
What mainly forms the right border of the heart?
atrium
28
What forms the inferior border of the heart?
right ventricle
29
What forms the left border of the heart?
left ventricle
30
What are the 4 layers of the pericardium and what are the inner and outer wall made up of?
Visceral pericardium - touches the heart/attached to the heart wall Pericardial space - contains serous fluid Parietal pericardium - lines tough fibrous sac called the fibrous pericardium Fibrous pericardium - fibrous sac squamous mesothelial cells
31
List the layer of the inside to outside of the heart starting from the insidice
lumen - endocardium (wall exposed to blood) - myocardium - epicardium/visceral pericardium - pericardial space (serous fluid) - parietal pericardium - Fibrous pericardium - outside pericardial sack
32
Name the components of the heart wall
endocardium - myocardium - visceral pericardium
33
What is the fibrous skeleton of the heart and what is its function?
It consists of four fibrous rings, each surrounding one of the valves (aortic, pulmonary, bicuspid and tricuspid) and is located at the base of the ventricles, between the atria and the ventricles. Its function is to provide electrical insulation (i.e. separate atria and ventricles electrically) and anchors the valve leaflets (mitral, tricuspid and aortic) of the heart giving attachment to the myocardium above and below
34
List the components of the conduction system of the heart in the correct order for conduction of an action potential through the heart
Sinoatrial node - Atrial myocardium - Atrioventricular node - Bundle branches - Purkinje fibres - Ventricular myocardium
35
What is the function SA node?
Acts as a pacemaker for the heart, independent to the nervous system. Allows the heart to produce its own electrical impulses stimulating its contraction, without nerual input from the brain/and or spinal cord
36
What is the function AV node?
1. Causes a delay of the wave of action potentials travelling through the muscle of the heart 2. allows time for the atria to contract (as mechanical contraction is a slower process than the electrical activation) and top up the volume of the ventricles, prior to ventricular contraction. 3. Without this delay, the action potential propagates at such a speed that the ventricles and atria would contract almost simultaneously. 4. It is a slow conducting electrical pathway between the atria and ventricles.
37
Which fibres (nerves) cause atrial and ventricular contraction?
atrial - SA node ventricular - AV bundle + purkinje fibres
38
What are the five stages of the cardiac cycle?
1. ventricular filling 2. atrial contraction 3. isovolumetric ventricular contraction (systole) 4. ventricular ejection 5. isovolumetric ventricular relaxation
39
Explain what occurs during ventricular filling
- This phase occurs when the pressure in the ventricle drops below that of the atrium - The mitral valve opens (quietly) and blood enters the ventricle - The ventricle fills about 80% of its capacity DIASTOLE
40
Explain what occurs during Atrial contraction
- The SA node fires and the atrium contracts to complete ventricular filling "20% topup"
41
Explain what occurs during isovolumetric contraction
- the ventricle begins to contract and blood lifts backwards towards the atrium - the mitral valve closes (first heart sound) - Ventricular pressure is still below that in aorta so the aortic valve remains closed. - For this brief period of rising pressure the ventricle is isolated from the rest of circulation with both inlet and outlet valves closed - hence ISOvolumetric (atrial P > ventricular P > arterial P) SYSTOLE FIRST HEART SOUND
42
Explain what occurs during ventricular ejection
- Systole continues - Ventricular Pressure exceeds aortic pressure and the aortic valve cusps open (quietly). - Blood is ejected into the aorta at the start the ventricle is pushing more blood into the aorta than what can flow out of the artery, the pressure in the ventricle and aorta continue to rise steeply. But as time goes on the rate of outward flow is lower than the rate of inward flow (as the muscle gets shorter and cant squeeze as hard as in the beginning) and aortic and ventricular pressure level off and begin to decrease.
43
Explain what occurs during Isovolumetric ventricular relaxation
- The ventricle relaxes, ventricular pressure drops suddenly - Flow in the aorta reverses and the aortic valve closes (SECOND HEART SOUND) as blood tries to re-enter ventricle - The mitral valve is closed because ventricular pressure is still exceeding atrial pressure (atrial P < ventricular P < aortic pressure) for a brief period the ventricle is isolated from the rest of the circulation. When this phase is completed the heart re-enters ventricular filling
44
What causes the two sounds of out heart beat and why are their sounds different?
1. mitral valve closing - inlet valve, larger - base sound, low "LUB" 2. aortic valve closing - outlet valve, smaller, higher sound "DUB"
45
What is the pressure of the ventricle during ventricular filling
> 0 mmHg lower than arterial and aortic
46
What is ventricular pressure after isovolumetic ventricular contraction is complete?
>80 mmHg
47
Describe the step of the cardiac cycle in terms of pressure, valves, sounds and volume
1. Ventricular filling - pressure: aortic pressure is higher than ventricular pressure ( >0 mmHg) which is lower than atrial pressure - valves: mitral valve open, aortic valve is closed - sounds: none - volume: approx. 80 ml 2. Atrial contraction (systole) - pressure: aortic pressure is higher than ventricular pressure (slowly increasing) which is lower than atrial pressure (slight incline) - valves: mitral valve open, aortic valve closed - sounds: none - volume: ventricle volume increases from 80 ml to 120 ml 3. Isovolumetric ventricular contraction - pressure: atrial pressure < ventricular pressure < aortic pressure (Pv rises from 0 to 80mmHg) - valves: mitral valve closed, aortic valve is closed - sounds: first heart beat - volume: doesn't change, remains 120 ml 4. Ventricular contraction - pressure: ventricular pressure exceeds aortic pressure, atrial pressure low. Aortic and ventricular pressure rise and fall together at the same pace - valves: mitral valve closed, aortic valve open - sounds: none - volume: starts to decline as ventricle blood goes to aorta 5. Isovolumetric ventricular relaxation - pressure: aortic pressure > ventricular pressure > atrial pressure (Pv drops from ~100 mmHg to 0 mmHg) - valves: mitral valve closed, aortic valve closed - sounds: second heart beat - volume: doesn't change, remains 50 ml 6. Ventricular filling - pressure: ventricular pressure below atrial pressure ( > 0 mmHg). Aortic pressure high - valves: mitral valve open, aortic valve closed - sounds: none - volume: from 50 ml back to 80 ml
48
What is the function of Elastic Arteries
During systole they expand to store the bolus of blood leaving the ventricle; then during diastole they push the blood out into the arterial tree by elastic recoil. Thus they smooth the pulsatile flow of blood leaving the ventricles
49
What is the function of Muscular arteries?
Distribute blood around the body at high pressure. Rate of blood flow is adjusted by using smooth muscle to vary the radius of the vessel
50
What is the function of arterioles
Control blood flow into capillary beds. These are the vessels in the circulation where the greatest pressure drop occurs. The degree of constriction of these vessels throughout the body determines total peripheral resistance which in turn affects mean arterial blood pressure
51
What is the function of capillaries?
Exchange of gases, nutrients and wastes between blood and the surrounding tissue fluid
52
What is the function of venules?
Low pressure vessels which drain capillary beds. They are the site where white blood cells leave the blood circulation to attack bacteria in the tissue alongside
53
What is the function of veins?
Thin-walled, low pressure vessels which drain blood back to the atria. Act as a reservoir which stores blood
54
Describe the structure of elastic arteries
very large vessels which have elastic walls. They have many thin sheets of elastin in the middle tunic
55
Describe the structure of muscular artieries
many layers of circular smooth muscle wrapped around the vessel in the middle tunic
56
Describe the structure of the arteriole
They have a thicker muscular wall relative to their size than any other blood vessel. Between one and three layers of smooth muscle wrapped around the vessel in the middle tunic
57
Describe the structure of capillaries
Tiny thin walled vessels - single layer of endothelium (with and external basement membrane) with a diameter just wide enough to admit one red blood cell
58
Describe the structure of venules
small ones have endothelium plus a little connective tissue. Larger ones have a single layer of smooth muscle
59
Describe the structure of veins
similar to a muscular artery, but much more compliant and thinner-walled (much less muscle and connective tissue.) Larger ones (especially in the legs) have valves which prevent backflow
60
What is the valve immediately upstream of the coronary arteries?
aortic valve
61
What is the function of the coronary arteries?
To supply the heart with oxygenated blood
62
What chamber do the cardiac veins drain into?
right atrium
63
How many classes of blood vessels are there? Name them.
Six - elastic artery, muscular artery, arteriole, capillary, venule, veins
64
What happens when the coronary arteries are narrowed to about 20% of their normal cross-sectional length?
significant obstruction of blood flow occurs resulting in ischemia (low oxygen supply) causing angina (chest pain). severe iscemia can lead to infarction (death ) of local myocardium
65
What are anastomoses
Artery to artery junctions between small penetrating branches of the main coronary arteries which are able to supply oxygenated blood to an ischaemic area of muscle
66
What does the P wave of an electrocardiogram represent?
depolarisation of the atria
67
What does the QRS complex represent?
depolarisation of the ventricles
68
What does the T wave represent?
repolerisation of the ventricles
69
What is a positive chronotrope?
something that increases heart rate
70
What is a positive inotrope?
something that increases contractility of the heart
71
How does the sympathetic nervous system influence heart function?
1. Increases heart rate and stroke volume 2. Increased spontaneous depolarisation of the SA and AV nodes 3. Increased contractility of ventricles and atria
72
How does the parasympathetic nervous system influence heart function?
1. decreased heart rate 2. decreased rate of spontaneous depolarisation of the SA and AV node
73
What is the intrinsic rate of SA node cells? What are these cells called? How is this regulated?
90 - 100 bpm pacemaker cells The nervous system: sympathetic and parasympathetic nerves/hormones
74
Describe the action potential in a ventricular contractile fibre
1. RAPID DEPOLERISATION: Na+ channels open, influx of Na+. membrane potential goes from ~ -90mV to ~+30mV within 1-2ms 2. EARLY REPOLERISATION: Na+ channels inactivated and K+ channels activated, producing efflux of K+ 3. PLATEU: Maintained depolarisation due to Ca2+ influx and K+ efflux is equal. ~200 ms 3. REPOLERISATION: Ca2+ channels close, K+ channels open, efflux of K+. Membrane potential back to ~- 90mV. Slower than depolarisation, ~20-50ms.
75
Where does the nervous system regulation of heart rate originate from?
medulla oblongata
76
What is a major stimulus that accounts for the rapid rise in the heart rate at the onset of physical activity?
proprioception
77
What two endocrine glands in the body are able to increase heart rate?
adrenal medulla and thyroid
78
Describe the features of the hearts conduction system
1. SA node fires spontaneously causing atrial contraction 2. Wave of action potential travels to AV node. (AV node is the only electrical connection between the atria and ventricles) 3. The wave travels slowly through this node, allowing time for mechanical contraction of the atria to top up the blood in the ventricles 4. Activation conducted through bundle of HIS, purkinje fibres then through ventricular myocardium causing ventricular contraction.
79
What does cardiac output refer to?
the amount of blood ejected into the aorta per minute
80
What is the equation used to calculate cardiac output?
CO =. HR X SV
81
Define stroke volume
The amount of blood ejected out of each ventricle each cardiac cycle
82
Define venous return
The amount of blood returning to the heart each minute from the venous system
83
Define cardiac reserve
the difference between the cardiac output at rest and the maximum cardiac output
84
Define preload
the stretch on the heart before it contracts
85
Define afterload
The amount of work the heart must do to generate a ventricular pressure sufficient enough to eject blood
86
Define contractility
the forcefulness of contraction
87
Describe the Frank-Starling Law of the heart. What does this ensure?
The stretch of the ventricular walls as the ventricle fills determines how forceful the contraction is - the more the muscle fibres are stretched, the more forceful the contraction. This ensures that the amount of blood returning to the heart is matched by the amount of blood leaving the heart (Venous return = Cardiac Output).
88
Where is stroke volume determined on the pressure-volume loop?
The volume in between the two straight parts of the loops
89
True/False The heart varies the supply of blood to the rest of the body, based on the demand from the body.
True
90
True/False An increase in venous return would result in an increase in preload, and so an increase in contractility and therefore stroke volume.
True
91
True/False In a stable system, the venous return should roughly equal the cardiac output.
True
92
True/False The left side of the heart pumps a larger volume of blood per contraction than the right side of the heart, due to having a thicker wall and so more contractile force.
False - Both sides of the heart pump the same volume of blood per contraction, as the sides must be balanced, otherwise accumulation of blood would occur
93
True/False Stroke volume is affected only by preload and afterload.
False - Stroke volume is affected by three factors: preload, afterload and contractility
94
What is ESV and EDV?
The EDV is the filled volume of the ventricle prior to contraction and the ESV is the residual volume of blood remaining in the ventricle after ejection.
95
What factors increase cardiac output?
Stroke volume - Increased preload (EDV) - Increased contractility (sympathetic, glucagon, thyroid, Ca2+) - decrease afterload (decreased arterial blood pressure during diastole) Heart rate - Nervous system (sympathetic) - Chemicals - Other factors (body temp, fitness, age)
96
Describe the pressure-volume curve
1. bottom left to right: Ventricular filling - pressure is low 2. bottom right, up: isovolumetric ventricular contraction - no change in volume, pressure increases to 80 mmHg 3. top right to top left: Ventricular ejection - pressure increases to 120 mmHg and then drops, volume decreases 4. top left to bottom left: isovolumetric ventricular relaxation - pressure drops back to approx. 0 mmHg
97
Label the points at which the valves open and close on the pressure-volume curve
1. mitral valve opens 2. mitral valve closed 3. Aortic valve opens 4. Aortic valve closed
98
What is the left ventricular end diastolic volume?
120ml
99
What is total peripheral resistance?
the amount of force affecting resistance to blood flow throughout the circulatory system
100
What is meant by blood pressure (mean/systolic/diastolic)?
pressure of circulating blood against vessel walls, which can vary throughout the cardiac cycle
101
What is capillary exchange?
exchange of material between blood and interstitial tissue
102
What is blood hydrostatic pressure?
the force exerted by the blood confined within blood vessels
103
What is interstitial fluid hydrostatic pressure?
mechanical pressure exerted on the interstitial fluid by the elastic recoil of the tissues in any region of the body
104
What is blood colloid pressure?
a form of osmotic pressure induced by the proteins in blood
105
What is interstitial fluid osmotic pressure?
the osmotic force which is the result of differences in water concentration between plasma and interstitial fluid
106
What is hypertension?
high blood pressure
107
What is bradycardia?
slow heart rate
108
What is Tachycardia?
fast heart rate
109
What are baroreceptors?
sense blood pressure
110
What does Poiseuille's law describe?
flow is related to factors such as viscosity
111
What is Angiotensin (II) ?
a vasoconstrictor peptide
112
What is a hemorrhage?
a release of blood from a broken blood vessel
113
What does Starlings Law describe?
force is related to how much stretch occurs
114
True/False Metabolically active tissues have extensive capillary networks as they use oxygen and produce waste products at a higher rate than inactive tissues
True
115
True/False The mean blood pressure in the aorta is closer to diastolic pressure than systolic pressure
True
116
Considering the distribution of blood among different types of blood vessels, if the blood volume of a person was 5 litres, approximately how much blood would be in the veins and venules, vs in the capillaries?
3.2 litres in the veins/venules (64%), 0.35 litres in capillaries (7%)
117
If someone has a deficiency in their level of plasma proteins (low plasma protein level), how would affect their blood colloid osmotic pressure and therefore capillary exchange?
Blood colloid osmotic pressure is lower than normal in a person with a low level of plasma proteins, therefore capillary reabsorption is low. the result is oedema
118
Arterioles are the blood vessel type that exert the most control over systemic vascular resistance. How do arterioles control systemic vascular resistance?
Via vasodilation and vasoconstriction
119
In which types of blood vessels is the velocity of blood flow fastest?
aorta and arteries
120
Which type of tissue are regulated by the cardiovascular centre in the brain stem? (more than one answer)
Smooth muscle in blood vessel walls, cardiac muscle in the heart
121
If a patient suddenly lost 15% of their blood volume and there was no adequate compensation, what would happen to their EDV, preload and stroke volume?
decrease
122
If a decrease in blood volume leads to a decrease in blood pressure, the decrease in blood pressure would be sensed by the ____ which are located in the ____ and ____
baroreceptors, aortic arch, carotid sinus
123
In response to a decrease in arterial pressure, sympathetic nerve activity to the heart would ___ and vagal (parasympathetic) activity to the heart would ___
increase, decrease
124
Considering the actions of the autonomic nerves in response to a decrease in arterial pressure, describe the effect of the change in sympathetic nerve activity on depolarization of pacemaker cells in the heart and thus heart rate.
When baroreceptors sense a drop in atrial pressure, sympathetic nerve activity is increased in the cardia accelerator nerves, These act on the SA node to increase in the rate of depolarization of the pacemaker cells
125
Describe the effect of an increase in sympathetic nerve activity on contractility of the heart
SNA via the cardiac accelerator nerves will also increase the contractility of the heart (contractility = force of contraction) This leads to a more forceful contraction, and therefore increased stroke volume at any particular pre-load
126
Describe the effect of a decrease in sympathetic nerve activity on total peripheral resistance
The decrease in frequency of sympathetic nerve activity causes vasodilation (of smooth muscle fibres) in systemic blood vessels. This increases radius of the lumen of the vessel, decreasing resistance to blood flow. This decreases the total peripheral resistance
127
What would be the predominant effect of a decrease in vagal activity?
The reduction in parasympathetic nervous activity would increase the heart rate
128
What is the equation for Mean Arterial Pressure/ Blood Pressure? What does it refer to?
MAP or BP = CO x TPR (total peripheral resistance) the average arterial pressure throughout one cardiac cycle, systole, and diastole.
129
Draw the pressures acting on the atrial and venous end of the capillaries
Atrial - BHP, BCOP, IFOP Venous - IFHP, BCOP, BHP
130
What is net filtration pressure (NFP)
NFP = pressures promoting filtration (BHP + IFOP) - pressures promotin reabsorption (BCOP + IFHP)
131
What happens to blood velocity when area increases?
velocity slows down
132
Why is blood pressure important?
It produces the driving force for exchange of oxygen and nutrients
133
Why is a stable arterial blood pressure important?
exchange of oxygen and nutrients at the capillaries
134
What is the order of arterial vessel blood flow?
elastic - muscular - arterioles - capillaries - venuoles - veins
135
electrical conductivity from SA to Atrial muscle is how fast?
0.5 m/s slow
136
electrical conductivity from Atrioventricular node is how fast? What does this result in?
0.05 m/s very slow - results in 100 m/s delay
137
electrical conductivity from AV bundle to purkinje fibres is how fast?
fast 5m/s
138
For muscular arteries flow is proportional to ?
the fourth power radius
139
From the coronary arteries, blood is drained from the myocardium by _____ which return blood to the ____ ?
cardiac veins - right atrium
140
What are vasomotor nerves and what are they responsible for?
sympathetic nerve fibres coming from the CV centre in medulla causes vasoconstriction, release norepinephrine, bind to alpha receptors
141
How is stroke volume calculated?
EDV - ESV
142
What factors govern EDV and ESV
EDV - preload ESV - afterload and contractility
143
What is systolic blood pressure?
the maximum amount of arterial pressure when the left ventricle in the heart contracts
144
What is diastolic blood pressure?
the minimum amount of arterial pressure when the left ventricle in the heart relaxes
145
What is vascular resistance?
the resistance in the circulatory system that is used to create blood pressure
146
What factors affect vascular resistance?
blood viscosity, vessel length and vessel diameter
147
What is Starlings equilibrium for capillary exchange?
the amount of fluid filtering outward from the arterial ends of capillaries equals almost exactly the fluid returned to the circulation by absorption
148
What type of blood vessel are coronary arteries?
muscular arteries
149
list the pressure ranges in the heart
RV: 5-27 mmHg LV: 8-120 mmHg RA: max 5 mmHg LA: max 8 mmHg
150
The second heart sound is split in two? what is the order of valve closure?
aortic valve and then pulmonary valve
151
How can cardiac veins be identifed?
cutting open left anterior vena cava, 2cm
152
Where can the fossa ovalis be seen in the sheep lab?
place finger in posterior vena cava - look into left atrium, see finger through soft and partly transparent part of interatrial septum

Medsci 142 (10 decks)

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