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Circulation > Blood pressure > Flashcards

Blood pressure Flashcards

1
Q

The systolic blood pressure reflects _

A

The systolic blood pressure reflects maxmimum pressure generated by the left ventricle during systole
* The aortic valve is open at this point and the intraventricular pressure equals the aortic pressure
* Normal ~120

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2
Q

Increasing SVR increases blood pressure; explain

A

Increasing systemic vascular resistance makes it more difficult for blood to flow from larger arteries –> smaller ones
* Vasoconstriction increases SVR

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3
Q

Name some factors that influence the SVR

A
  • Autonomic nervous system input
  • Vessel stretch (myogenic reflex)
  • Local factors (nitric oxide, oxygen, co2)
  • Circulating signaling molecules (vasopressin, endothelin)
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4
Q

How does the body respond to hypovolemic shock?

A

In response to hypovolemic shock, the body:
* Induces vasoconstriction
* Increases contractility
* Increases heart rate

In an attempt to compensate for the volume loss
* The desired blood pressure should be high enough to maintain organ perfusion, but not so high as to decrease cardiac output

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5
Q

In cardiogenic shock, the CO drops due to _ and _ cannot compensate adequately, leading to severe hypotension and organ failure

A

In cardiogenic shock, the CO drops due to myocardial injury and peripheral vasoconstriction and tachycardia cannot compensate adequately, leading to severe hypotension and organ failure

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6
Q

Three systems work together to regulate BP: _ , _ , and _

A

Three systems work together to regulate BP: cardiovascular , renal , and neural

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7
Q

Mean arterial pressure (MAP) equation

A

Mean arterial pressure (MAP) is the average arterial blood pressure for one cardiac cycle

MAP = SVR * CO

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8
Q

MAP represents _

A

Mean arterial pressure (MAP) represents the average arterial blood pressure for one cardiac cycle
* A MAP of less than 60 is usually fatal because tissues cannot stay perfused

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9
Q

Normal MAP is between _ and _

A

Normal MAP is between 85-95 mmHg
* The heart spends about 2/3 of its time in diastole (80)
* About 1/3 is spent in systole (120)

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10
Q

We have special baroreceptors in the _ and _ that can sense changes in arterial stretch and send signals to the _

A

We have special baroreceptors in the aorta and carotid artery that can sense changes in arterial stretch and send signals to the medulla

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11
Q

Nerve signals from baroreceptors get sent to the medulla via cranial nerves _ and _

A

Nerve signals from baroreceptors get sent to the medulla via cranial nerves IX and X

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12
Q

The _ is responsible for regulating blood pressure in the long term

A

The kidney is responsible for regulating blood pressure in the long term
* Causes us to urinate less when blood volume or blood pressure is low
* Causes us to urinate more when these things are high
* Also controls absorption of NaCl and water

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13
Q

In patients with end-stage kidney disease, we expect to see (increased/reduced) urine output and (high/low) blood pressure

A

In patients with end-stage kidney disease, we expect to see reduced urine output and high blood pressure
* Rely on dialysis to remove excess fluid

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14
Q

We have separate volume receptors (stretch receptors) in the atria and ventricles that when stretched by high blood volume, release _

A

We have separate volume receptors (stretch receptors) in the atria and ventricles that when stretched by high blood volume, release natriuretic peptides –>causes renal sodium and water excretion

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15
Q

The greatest density of baroreceptors lies around the _ and _

A

The greatest density of baroreceptors lies around the aortic arch and carotid sinus

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16
Q

Afferent signals to the brain from baroreceptor stretch is carried by _ and _
Efferent signals back to the heart are carried by _ and _

A

Afferent signals to the brain from baroreceptor stretch is carried by glossopharyngeal nerve IX and vagus nerve X
Efferent signals back to the heart are carried by sympathetic nerves (traveling via the spinal cord) and parasympathetic nerves (traveling via vagus nerve)

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17
Q

The carotid sinus afferent nerves use _ cranial nerve to transmit signals to the brain

A

The carotid sinus afferent nerves use glossopharyngeal (CN IX) to transmit signals to the brain

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18
Q

The aortic arch afferent nerves use _ cranial nerve to transmit signals to the brain

A

The aortic arch afferent nerves use vagus nerve (CN X) to transmit signals to the brain

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19
Q

How do baroreceptors transmit signals?

A

Baroreceptors will fire on each heartbeat, increasing firing when the heartbeat is faster and decreasing firing when the heartbeat slows

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20
Q

Explain the series of events following baroreceptors signal high blood pressure

A
  1. Baroreceptor firing is high because of high BP
  2. Signals get sent to the medulla
  3. Signals are then processed in the hypothalamus
  4. Efferent nerves go to the:
    * SA and AV node: to reduce heart rate
    * Cardiac myocytes: to reduce contractility
    * Arteries: to relax their smooth muscle (dilate) and drop SVR
    * Veins: to relax smooth muscle and lower venous pressure and increase capacitance
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21
Q

Carotid massage can be used in situations of _ to cause _

A

Carotid massage can be used in situations of pathologic tachycardia to cause fooling of baroreceptors –> make the body think there is hypertension –> reduce firing rate

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22
Q

How does the body respond to a decrease in blood pressure?

A
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23
Q

The _ reflex is a reflex on the “venous side” whereby stretching of the right atrium will cause _

A

The Bainbridge reflex is a reflex on the “venous side” whereby stretching of the right atrium will cause increase heart rate
* If right atrium stretches it is usually because of volume overload –> tachycardia relieves volume overload by increasing cardiac output

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24
Q

Which cirulating molecules have the effect of lowering blood pressure?

A

Molecules that lower blood pressure include:
* Natriuretic peptides
* Nitric oxide
* Histmine
* Bradykinin

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25
Q

The two natriuretic peptides that work to _ are _ and _

A

The two natriuretic peptides that work to promote urinary natriuresis (loss of sodium in the urine) are:
* Atrial natriuretic peptide (ANP)
* Brain natriuretic peptide (BNP)

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26
Q

ANP is released from _
BNP is released from _

A

ANP is released from atrial cardiomyocytes
BNP is released from ventricles

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27
Q

One mechanism by which ANP works is to inhibit sodium transporters in the _

A

One mechanism by which ANP works is to inhibit sodium transporters in the renal tubules –> decreasing sodium absorption
* This leaves more sodium in the urine which drags water with it and decreases blood pressure

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28
Q

The drug nitroglycerin is used to dilate coronary arteries in patients with angina; it works via _ molecule

A

The drug nitroglycerin is used to dilate coronary arteries in patients with angina; it works via nitric oxide release

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29
Q

Nitric oxide is predominantly released by _ in the body and works to induce _

A

The drug nitroglycerin is used to dilate coronary arteries in patients with angina; it works via nitric oxide (NO) molecule

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30
Q

NO has receptors on _ cells ; it can act systemically but also via action of endothelial cells immediately adjacent to an area of endothelial damage

A

NO has receptors on vascular smooth muscle cells ; it can act systemically but also via action of endothelial cells immediately adjacent to an area of endothelial damage

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31
Q

Histmine normally acts as a _ to increase blood flow to sites exposed to _

A

Histmine normally acts as a mild vasodilator to increase blood flow to sites exposed to allergens or inflammation
* Also has a role in alertness, nasal capillary permeability, and gastric acidity

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32
Q

Anaphylactic shock is _

A

Anaphylactic shock is over-release of histamine that causes too much vasodilation –> hypoperfusion of organs

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33
Q

The main cells secreting histamine are _ and _

A

The main cells secreting histamine are mast cells and basophils

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34
Q

Another vasodilator _ is primarily released during disease processes and promotes inflammation; it requires proteases called _ to cleave and release its active form

A

Another vasodilator, bradykinin is primarily released during disease processes and promotes inflammation; it requires proteases called kallikrein to cleave and release its active form

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35
Q

Our primary bradykinin receptor is _ which is expressed in normal tissues, including vascular endothelial cells; The receptor _ is only expressed following burns, trauma, or inflammation

A

Our primary bradykinin receptor is B2 which is expressed in normal tissues, including vascular endothelial cells; The receptor B1 is only expressed following burns, trauma, or inflammation

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36
Q

One significant adverse reaction of ACE inhibitors that is mediated by bradykinin is _

A

One significant adverse reaction of ACE inhibitors that is mediated by bradykinin is angioedema

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37
Q

Name two circulating molecules that work to increase blood pressure

A

Molecules that increase BP:
* Endothelin
* Vasopressin

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38
Q

_ is a molecule that gets released in response to shearing force from high blood flow or by angiotensin II and ADH

A

Endothelin is a molecule that gets released in response to shearing force from high blood flow or by angiotensin II and ADH
* Endothelin gets elevated in pulmonary hypertension –> leads to shortness of breath

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39
Q

Endothelin binds receptors _ and _ and induces a calcium mediated pathway that allows _

A

Endothelin binds receptors ET-A and ET-B and induces a calcium mediated pathway that allows contraction of smooth muscle fibers

40
Q

Vasopressin has duel effects of promoting blood pressure to increase by inducing _ and _

A

Vasopressin has duel effects of promoting blood pressure to increase by inducing vasoconstriction and increased reabsorption of water by the kidneys

41
Q

Vasopressin is released by _ during states of _

A

Vasopressin is released by posterior pituitary gland during states of high serum osmolality or low effective circulating volume

42
Q

What is the equation for blood flow (Q)

A

Blood flow (Q) = deltaP (change in pressure) / R (vessel resistance)

Q = ΔP/R

43
Q

Hagen-Poiseuille Law

A

Q = (ΔP)πr4/8ηL

44
Q

Of all of the variables in Hagen-Poiseuille Law, the _ has the greatest influence over resistance and blood flow

A

Of all of the variables in Hagen-Poiseuille Law, the radius has the greatest influence over resistance and blood flow

45
Q

The Hagen-Poiseuille Law cannot be applied to areas of inconsistant blood flow or areas with turbulent flow like _ and _

A

The Hagen-Poiseuille Law cannot be applied to areas of inconsistant blood flow or areas with turbulent flow like aorta and brachial artery

46
Q

How can we determine blood flow from velocity?

A
47
Q

As blood moves from larger vessels to a series of continually smaller arteries and arterioles, the total cross-sectional area (increases/ decreases) and the velocity of blood (increases/ decreases)

A

As blood moves from larger vessels to a series of continually smaller arteries and arterioles, the total cross-sectional area increases and the velocity of blood decreases

48
Q

Why is it important that the velocity of blood slows down at the capillaris?

A

It gives the capillaries enough time to deliver oxygen and nutrients to the cells and pick up waste products

49
Q

When we measure blood pressure we are actually measuring their _ pressure

A

When we measure blood pressure we are actually measuring their arterial blood pressure in large arteries like the brachial artery

50
Q

Equation for vessel compliance

A

Compliance = change in vessel volume / change in pressure

51
Q

Capillaries or thin veins will stretch with only a small amount of pressure added, giving it (high/ low) compliance

A

Capillaries or thin veins will stretch with only a small amount of pressure added, giving it high compliance
* Veins > arterioles > large arteries

52
Q

The aorta has (high/ low) compliance but a strong inward recoil force when it is stretched

A

The aorta has low compliance but a strong inward recoil force when it is stretched –> rebound is important to drive blood out to systemic circulation

53
Q

(True/ False) The damage to blood vessels in hypertension is due to high pressure

A

False; The damage to blood vessels in hypertension is not due to high pressure itself, but rather the abnormal wall tension generated by high pressure

54
Q

Equation for wall tension

A

Wall tension = change in pressure * radius

T = ΔP × r

55
Q

What is the order of wall thickness in various vessels

A

Wall thickness is greatest in:
Large arteries > veins > capillaries

56
Q

Compare the direction of hydrostatic pressure to oncotic pressure

A
57
Q

The capillary or colloid osmotic pressure is exerted by _

A

The capillary or colloid osmotic pressure is exerted by albumin, which causes the capillaries to pull water towards it

58
Q

Draw the four starling forces

A
59
Q

The capillary fluid permeability coefficient (Kf) prepresents _

A

The capillary fluid permeability coefficient (Kf) prepresents how leaky the capillary is for a given filtration pressure

60
Q

The reflection coefficient for protein (σ) measures _

A

The reflection coefficient for protein (σ) measures how much of the protein that determines the oncotic pressure can leak out
* This value will be between 0-1 with 1 being no leakage

61
Q

The reflection coefficient for protein (σ) will be large with capillaries in the _ but small for capillaries in the _

A

The reflection coefficient for protein (σ) will be large with capillaries in the kidney glomerulus, where essentially no protein leaks out but small for capillaries in the liver sinusoid, where albumin leaves easily

62
Q

Under normal physiologic conditions, the net driving force at the proximal end of the capillary is _ while the net driving force at the distal end is _

A

Under normal physiologic conditions, the net driving force at the proximal end of the capillary is +10, promoting filtration while the net driving force at the distal end is -9, promoting reabsorption
* The difference is about +1, promoting filtration or some excess fluid left in the interstitial space
* This is why lymphatic vesdels are needed to return fluid back into the circulation

63
Q

In congestive heart failure, if the left ventricle fails the blood backs up into the _

A

In congestive heart failure, if the left ventricle fails the blood backs up into the pulmonary circulation
* Pulmonary capillary hydrostatic pressure rises and we end up with pulmonary edema
* Fluid in alveoli –> SOB

64
Q

In congestive heart failure, if the right ventricle fails, the blood backs up to the _

A

In congestive heart failure, if the right ventricle fails, the blood backs up to the systemic circulation
* We end up with peripheral edema in the legs and feet

65
Q

Describe the mechanism of local regulation of blood flow such as how we can increase the blood flow to our legs when running

A

Smooth muscle cells that surround a vessel stretch or detect local environment (nitric oxide, oxygen, carbon dioxide) and they are able to dilate or constrict
* They can dilate to make more blood flow there
* Or constrict to have less blood flow

66
Q

Myogenic mechanism

A

Myogenic mechanism is sustained muscle contraction (tone) generated by the vascular smooth muscle itself without influenc of external stimuli like nerves or homrones
* An increase in blood pressure stretches the wall and causes the smooth muscles cells to contract, reducing blood flow –> keeps perfusion of tissues constant

67
Q

Steps of NO production

A
  1. Nitric oxide synthase (NOS) within the endothelial cells uses L-arginine and other cofactors to make nitric oxide.
  2. Nitric oxide diffuses locally into the smooth muscle cells.
  3. Nitric oxide activates guanylyl cyclase to turn guanosine triphosphate (GTP) into cyclic guanosine monophosphate (cGMP).
  4. cGMP promotes smooth muscle relaxation by inhibiting calcium entry into the cell. This activates potassium channels (causing hyperpolarization) and myosin–light-chain phosphatase (MLCP).
  5. MLCP dephosphorylates myosin light chains, leading to smooth muscle relaxation.
68
Q

Raynauds disease is an extreme case of _ in response to cold temperaturs

A

Raynauds disease is an extreme case of vascular vasoconstriction in response to cold temperaturs

69
Q

The blood flow through the LCA is the lowest during _

A

The blood flow through the LCA is the lowest during systole
* The left ventricle is exerting compressive forces on the arteries, arterioles, and capillaries –> occludes LCA

70
Q

Why does the blood flow through the RCA fluctuate much less than the LCA?

A

Wall tension of the right ventricle is much lower as it pumps into the low-resistance pulmonary circulation

71
Q

About _ percent of total LCA blood flow happens during diastole

A

About 75% of total LCA blood flow happens during diastole

72
Q

Describe the blood supply to the myocardium

A
  • Epicardial arteries run on the outside surface of the heart
  • Intramural arteries dive deep into the myocardium
  • Subendocardial arteries supply the cardiac muscle
73
Q

Why does the flow of blood to the myocardium decrease during systole?

A
  1. subendocardial arteries are compressed
  2. when the aortic valve is open it blocks the epicardial arteries
74
Q

Three main factors that achieve coronary artery dilation

A
  1. Decrease in ATP
  2. Increase in adenosine
  3. Increase in nitric oxide
75
Q

Stage 1 hypertension is defined as systolic blood pressure _ and/or diastolic blood pressure _

A

Stage 1 hypertension is defined as systolic blood pressure 130-139 and/or diastolic blood pressure 80-89

76
Q

About 95% of individuals have primary hypertension, also known as _ which does not have an identibiable cause

A

About 95% of individuals have primary hypertension, also known as essential hypertension which does not have an identibiable cause

77
Q

What is secondary hypertension?

A

Secondary to another medical condition

78
Q

Most individuals with hypertension are asymptomatic; however hypertensive emergency may manifest with:

A

Hypertensive emergency:
* Severe chest pain
* Altered mental status
* Blurred vision
* SOB
* Decreased urine output
* Headache

79
Q

What happens to the heart after persistent high blood pressure?

A

Left ventricular hypertrophy –> heart no longer relaxes well during diastole –> poor filling, reduced stroke volume

80
Q

The most common mechanism for primary hypertension is _

A

The most common mechanism for primary hypertension is elevated systemic vascular resistance (SVR)
* Can be due to vessel walls thickening
* Can also be due to uncoupling of the events that cause vasoconstriction vs vasodilation

81
Q

Epinephrine and Norepinephrine released by the SNS and adrenal medulla act on _ receptors to increase vasoconstriction –> increases BP

A

Epinephrine and Norepinephrine released by the SNS and adrenal medulla act on alpha receptors to increase vasoconstriction –> increases BP; also activates RAAS
* Some people are very sensitive to catecholamines

82
Q

Hypertension can also result from _ , a response to increased stroke volume

A

Hypertension can also result from increased cardiac output , a response to increased stroke volume
* The increased cardiac output causes peripheral vessels to constrict, raising SVR and raising BP
* This happens in patients who are sensitive to salt

83
Q

How does the kidney react to persistent high blood pressure?

A

The renal blood vessels will try to resist BP by thickening the walls of its arteries and arterioles –> leads to renal hypoperfusion and fibrosis

84
Q

Types of secondary hypertension

A

ABC(2)DE:
Apnea,
Bruits (seen in renal artery stenosis and fibromuscular dysplasia),
Catecholamines (pheochromocytoma) and Chronic kidney disease (CKD),
Drugs (oral contraceptive pills, NSAIDs, pseudoephedrine, cocaine, caffeine, amphetamines, and steroids), and Endocrine disorders (hyperaldosteronism, hypercortisolism, and thyroid dysfunction)

85
Q

In order to be diagnosed with hypertensive emergency, a patient must have evidence of _

A

In order to be diagnosed with hypertensive emergency, a patient must have evidence of end-organ damage
* Patient might be asymptomatic or have malaise, fatigue, etc

86
Q

Hypertensive emergency is thought to be a result of _ due to humoral vasoconstrictors like _

A

Hypertensive emergency is thought to be a result of abrupt increases in SVR due to humoral vasoconstrictors like catecholamines, angiotensin-II, endothelin
* Rapid increase in blood pressure –> endothelial injury –> activation of the coagulation cascade –> necrosis of the arterioles

87
Q

The normal response of the blood vessels to hypertension is _

A

The normal response of the blood vessels to hypertension is vasoconstriction
* This is a part of our normal autoregulation whereby organs maintain a relatively constant perfusion rate regardless of systemic blood pressure

88
Q

During a hypertensive emergency, autoregulation can fail in places like our central nervous system which leads to _

A

During a hypertensive emergency, autoregulation can fail in places like our central nervous system which leads to arterial dilation and hyperperfusion –> increases intracranial pressure
* This is called hypertensive encephalopathy

89
Q

In the heart, hypertensive emergency can lead to _

A

In the heart, hypertensive emergency can lead to myocardial ischemia –> myocardial infarction (MI)
* Or the shear force by the BP can tear the tunica intima –> aortic dissection

90
Q

In the kidneys, hypertensive emergency can lead to _

A

In the kidneys, hypertensive emergency can lead to acute kidney injury –> narrowed renal and glomerular blood vessels reduce blood flow to the glomerulus and drop the GFP

91
Q

Name some common drug classes that can treat hypertension

A
92
Q

If we are treating a patient who has hypertension and osteoporosis, _ might be a good choice

A

If we are treating a patient who has hypertension and osteoporosis, thiazides might be a good choice
* They act on the kidneys to induce sodium and water loss
* They also increase serum calcium (increase Ca2+ reabsorption)

93
Q

Thiazide drugs work specifically in the kdiney by inhibiting _ in the _

A

Thiazide drugs work specifically in the kidney by inhibiting Na+/Cl- symporter in the distal convoluted tubule (DCT)

94
Q

The main class of antihypertensive drugs include (3):

A
  1. Thiazide diuretics
  2. ACE inhibitors
  3. Calcium channel blockers (CCBs)
95
Q

Thiazide diuretics block Na+ and Cl- _

A

Thiazide diuretics block Na+ and Cl- reabsorption –> leaves more Na+ in the urine –> water follows

Circulation (12 decks)

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