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Physiology > Cardio phys: Exam #2 review > Flashcards

Cardio phys: Exam #2 review Flashcards

0
Q

What is the formula for cardiac output? What is the average cardiac output in adults?

A

Cardiac output = Stroke volume (SV) x Heart rate

Normal cardiac output for adults is 4,900 - 5,600 mL/min

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1
Q

What is the formula for ejection fraction (EF)? What is the normal ejection fraction for adults?

A

EF = stroke volume (SV)/initial volume.

Normal is 55-70% in adults.

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2
Q

Define cardiac preload

A

Preload is the end DIASTOLIC pressure that stretches the R or L ventricle of the heart to its greatest geometric dimensions under variable physiologic demand. IN OTHER WORDS: It is the initial stretching of cardiomyocytes PRIOR to contraction; therefore, it is related to the sarcomere length at the end of diastole.

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3
Q

What are the effects of increased preload on SV, CO, and work?

A

SV (stroke volume): Increased
CO (cardiac output): Increased
Work: Increased

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4
Q
  1. ) If all variables remain constant, what does an increase in left ventricular end diastolic volume do?
  2. ) What variables must remain constant?
A
  1. ) Increased cardiac output.

2. ) Afterload and contractility

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5
Q

What is the consequence of an increased preload with a constant ejection fraction?

A

Increased cardiac output due to increased stroke volume

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6
Q

What is an analogous term for cardiac preload?

A

Ventricular filling (end diastolic volume)

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7
Q

Give an equation for myocardial “work”

A

Stroke volume X aortic pressure

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8
Q
  1. ) What are consequences of increased myocardial work?

2. ) How can work be reduced?

A
  1. ) Death…High BP exacerbates this
  2. ) Afterload reduction, vasodilation
    * Less work = less O2 consumed*
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9
Q

Aortic stenosis (AS) equates to an increased _______ = MORE WHAT?

A

INCREASED Afterload = MORE WORK

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10
Q

How many mL/min of O2 do we consume?

A

250mL O2/min

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11
Q

What is the law of Laplace (in words and equation)?

A

The law of Laplace for a sphere (i.e. the approximate shape of the heart) states that pressure correlates directly with tension and wall thickness and correlates inversely with radius –In other words, the law of Laplace for a sphere states that the greater the thickness of the wall of the sphere (e.g., left ventricle), the greater the pressure that can be developed.

Wall tension (T) = Pressure (P) X Radius (r)

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12
Q

Isovolumetric ventricular contraction begins with which EKG phase?

A

QRS

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13
Q

What is the most important factor contributing to cardiac output?

A

End-diastolic volume

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14
Q

What is the maximum right atrial pressure for filling?

A

4 mmHg

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15
Q

What is the minimum volume of blood needed to fill venous capacity and therefore detect a pulse?

A

4 L

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16
Q
  1. ) By what means can you empty the heart fastest? Why?

2. ) What types of medications do this?

A
  1. ) Venous dilation, i.e. increasing unstressed volume, because the veins contain the greatest volume of blood (60% of total vasculature).
  2. ) Venous dilators –> Nitrates/nitroglycerine/amyl nitrate, Morphine (acute pulmonary edema), furosemide, Sildenafil (nitric oxide drugs), Prostacyclin
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17
Q

What effect does a diuretic have on preload?

A

Decreases preload by lowering volume

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18
Q

Describe the speed and mediation of the baroreceptor reflex

A

Attempts to restore Pa to set-point in A MATTER OF SECONDS.

Neurally mediated

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19
Q

Regarding baroreceptors (mechanoreceptors), what effect does stretching have on their action potential?

A

Increased stretch from increased ARTERIAL PRESSURE causes an INCREASE IN FIRING RATE of the afferent nerves.

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20
Q

What are baroreceptors most sensitive to (2)?

A

While they are sensitive to absolute level of pressure, they are EVEN MORE SENSITIVE to CHANGES IN PRESSURE (∆P) and RATE OF CHANGE IN PRESSURE.

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21
Q

What is the strongest stimulus for baroreceptors?

A

RAPID change in arterial pressure

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22
Q

What are two potential physiological causes for hypertension?

A
  1. ) A defect that decreases sensitivity of baroreceptors to increased BP, or…
  2. ) Increase in the BP set-point of the brain stem centers.
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23
Q

Describe the parasympathetic outflow that controls BP

A

The PS outflow is the effect of the VAGUS NERVE on the SA node to decrease the heart rate.

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24
Q

Parasympathetic activity in the SA node is mediated by which nerve?

A

The VAGUS NERVE

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25
Q

Besides helping to decrease heart rate, what else does decreasing sympathetic activity in the heart do?

A

Decreases cardiac contractility

p.161

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26
Q

What effect does increasing venous compliance have on unstressed volume?

A

Increases unstressed volume

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27
Q

What is the affect on heart rate when baroreceptors detect an increase in arterial pressure?

A

Baroreceptors direct a DECREASE in heart rate

p.162

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28
Q

Describe the speed and method of regulation of the renin- angiotensin system

A

Much slower than baroreceptor reflex. Renin-angiotensin acts by regulating BLOOD VOLUME

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29
Q

A decrease in renal perfusion (due to a decrease in Pa) is detected by mechanoreceptors in…..

A

Afferent arterioles in the kidney

p.162

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30
Q

In the renin-angiotensin system, a decrease in Pa causes _____ to be converted into _____ in the ______ cells.

A

Prorenin to be converted into renin in the juxtaglomerular cells

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31
Q

Renin secretion is increased by stimulation of 1.) _______ and 2.) by modification of what receptor type (give example of drug[s])?

A
  1. ) Stimulation of renal sympathetic nerves

2. ) Beta-1 agonists (e.g. isoproterenol)

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32
Q

Renin secretion is decreased by what type of drugs?

A

Beta-1 antagonists, e.g. propranolol

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33
Q

Renin is a(n) _____

A

enzyme

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34
Q

What is the substrate for renin?

A

Angiotensinogen

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35
Q

Angiotensin I is converted to angiotensin II in the _____ and ______, catalyzed by what?

A

In the lungs and kidneys.

Catalyzed by angiotensin-converting enzyme (ACE)

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36
Q

Angiotensin-converting inhibitors (aka _____) such as ______, block the production of angiotensin II and all of its physiological actions.

A

aka ACEi (ACE inhibitors), such as Captopril

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37
Q
  1. ) Angiotensin II elicits biological reactions where (4)?

2. ) What does it activate?

A
  1. ) Adrenal cortex, vascular smooth muscle, kidneys, and brain.
  2. ) Type 1 protein-coupled angiotensin II receptors (AT1 receptors)
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38
Q

What does losartan do?

A

It is an AT1 inhibitor that blocks the action of angiotensin II at the level of target tissues.

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39
Q

The actions of aldosterone require….

A

Gene transcription and new protein synthesis in the kidney

p.163

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40
Q

Describe the action of angiotensin II on the adrenal cortex

A

Angiotensin II acts on the zona glomerulosa cells of the adrenal cortex to stimulate synthesis and secretion of aldosterone.

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41
Q

Describe the action of aldosterone

A

Aldosterone acts on the principal cells of the renal distal tubule and collecting duct to INCREASE NA+ REABSORPTION, thereby increasing ECF and blood volume.

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42
Q

What accounts for the slow response time of the renin-angiotensin system?

A

The gene transcription and protein production required by aldosterone action.

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43
Q

What, if any, DIRECT action does angiotensin have on the kidney?

A

It stimulates Na+-H+ exchange in the renal proximal tubule and INCREASES reabsorption of Na+ and HCO3-
p.163

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44
Q

What action, if any, does angiotensin have on the hypothalamus?

A

It acts on the hypothalamus to increase THIRST and water intake. *It also stimulates secretion of Antidiuretic hormone (ADH), which increases water reabsorption in collecting ducts

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45
Q
  1. ) How does angiotensin II act on arterioles?
  2. ) What is the effect?
  3. ) What is the overall result?
A
  1. ) Acts directly on arterioles by binding to G protein-coupled receptors and activating an IP3/Ca2+ second messenger system to cause
  2. ) VASOCONSTRICTION
  3. ) Increase in TPR = Increased Pa
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46
Q

What does ADH do?

A

Increases water reabsorption in the renal collecting ducts

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47
Q

What activates the renin-angiotensin II system?

A

Decrease in Pa

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48
Q

The response of the peripheral chemoreceptors to decreased arterial PO2 is greater when…(2)

A
  1. ) PCO2 is increased, or…
  2. ) pH is decreased
    p. 164
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49
Q
  1. ) What is the bodies response to decreased arterial PO2?

2. ) What is the result (2)?

A
  1. ) Increased firing rate of afferent nerves from the carotid and aortic bodies that activates sympathetic vasoconstrictor centers.
  2. ) The result is arteriolar vasoconstriction in SKELETAL MUSCLE, RENAL, and SPLANCHNIC VASCULAR BEDS.
    p. 165
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50
Q

Changes in what stimulate medullary chemoreceptors?

A

PCO2 and pH

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51
Q

What are the physiologic responses to brain ischemia?

A

Cerebral PCO2 increases, pH decreases –> Medullary chemoreceptors detect this and direct an INCREASE IN SYMPATHETIC OUTFLOW that causes intense arteriolar vasoconstriction in many vascular beds and an increase in TPR.

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52
Q

What is the Cushing reaction?

A

The physiologic response to increased intracranial pressure as follows: Intracranial pressure compresses cerebral arteries = decreased perfusion to brain = increased PCO2 = decreased pH. The medullary chemoreceptors respond by increasing sympathetic outflow to the blood vessels, thereby increasing TPR and Pa.
p.166

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53
Q

Where are the following present and what do they do:

  1. ) V1 receptors
  2. ) V2 receptors
A
  1. ) V1: Present in vascular smooth muscle…They respond to ADH by causing vasoconstriction of arterioles and, hence, INCREASED TPR.
  2. ) V2: Present in principal cells of the renal collecting duct…They are involved in water reabsorption in the collecting ducts and the maintenance of body fluid osmolarity.
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54
Q

Where is ADH secreted from?

A

Posterior pituitary

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55
Q

Where are low pressure baroreceptors located? What is another name for them?

A

Cardiopulmonary (low-pressure) baroreceptors are located in the veins, atria, and pulmonary arteries.

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56
Q

What increases ADH secretion (2)?

A

ADH secretion is stimulated by: Increases in serum osmolarity, and by decreases in blood volume and blood pressure

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57
Q

What do cardiopulmonary baroreceptors detect? Why are they located where they are?

A

They detect changes in blood volume. They are located on the venous side of circulation because that is where most of the blood volume is held.
p.166

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58
Q

What is secreted by the atria in response to increased atrial pressure? What is its effect?

A

Atrial natriuretic peptide (ANP). It relaxes smooth muscle, which results in vasodilation and decreased TPR.

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59
Q

What is the effect of ANP on the kidneys?

A

Vasodilation, which leads to INCREASED NA+ and WATER EXCRETION – thereby decreasing total body Na+ content, ECF volume, and blood volume.

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60
Q

What is the main effect of ADH secretion?

A

Increased water reabsorption in the collecting ducts = REDUCED WATER SECRETION, i.e. WATER RETENTION, i.e. INHIBITS URINE PRODUCTION = INCREASED BP.
p.165

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61
Q

What is the primary method by which cardiopulmonary baroreceptors respond to an increase in blood volume?

A

Increasing excretion of Na+ and water.

p.165

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62
Q

What is the Bainbridge reflex?

A

An increase in heart rate in response to an INCREASE IN PRESSURE at the cardiopulmonary baroreceptors (atrial)

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63
Q
  1. ) Which gasses readily cross the capillary wall by diffusing through the endothelial cells?
  2. ) Why?
  3. ) What drives the diffusion?
A
  1. ) O2 and CO2
  2. ) Because they are highly lipid soluble.
  3. ) Diffusion is driven by the partial pressure gradient for the individual gasses
    p. 166
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64
Q
  1. ) What substances cannot readily cross endothelial cell membranes (capillaries)?
  2. ) Why?
  3. ) How must they diffuse across?
A
  1. ) Water, ions, glucose, amino acids, etc.
  2. ) Because they are not lipid soluble.
  3. ) Water soluble substances must diffuse in the AQUEOUS CLEFTS BETWEEN ENDOTHELIAL CELLS
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65
Q

In capillary blood, only ____ contributes to the effective osmotic pressure. Why?

A

Only PROTEIN contributes to the effective osmotic pressure. WHY???
p.166

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66
Q

What is the term for the effective osmotic contributed by protein?

A

Colloidosmotic pressure or oncotic pressure

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67
Q

What is the definition of filtration?

A

Net fluid movement OUT OF a capillary into the interstitial fluid

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68
Q

What is the definition of absorption?

A

Net fluid movement from the interstitium INTO the capillary

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69
Q

The magnitude of fluid movement across a capillary for a given pressure difference is largest for capillaries with a HIGHER or LOWER Kf?

A

Higher Kf = Greater magnitude of fluid movement

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70
Q

The magnitude of fluid movement from/to capillaries is determined by the what?

A

Hydraulic conductance (Kf), i.e. water permeability of the capillary.

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71
Q

Given an example of a vessel with a:

  1. ) High Kf
  2. ) Low Kf
A
  1. ) Glomerular capillaries
  2. ) Cerebral capillaries
    p. 167
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72
Q

Is capillary hydrostatic pressure closer to arterial or venous pressure? Why?

A

Closer to ARTERIAL PRESSURE. WHY??? I DUNNO!

p.167

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73
Q
  1. ) What is capillary hydrostatic pressure (Pc)?

2. ) What determines it?

A
  1. ) A force favoring filtration OUT OF the capillary

2. ) Determined by both arterial and venous pressures (but more so by venous pressure).

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74
Q

What affects capillary hydrostatic pressure (Pc) more, changes in arterial or venous pressure? Why?

A

Changes in venous pressure. Why? I DUNNO!

p.168

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75
Q

Pc is highest and lowest in which places?

A

Highest: Arteriolar end of capillary
Lowest: Venous end of capillary
p.168

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76
Q

What is the lymphatic system responsible for?

A

Returning interstitial fluid and proteins to the vascular compartment.
p.168

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77
Q

Define all of the parameters/variables in the Starling Equation, as well as their effects on capillary filtration

A

Jv =Kf[(Pc −Pi)−(πc −πi)]

where:
Jv = Fluid movement (mL/min)
Kf = Hydraulic conductance (mL/min • mm Hg)
Pc = Capillary hydrostatic pressure (mm Hg)
Pi = Interstitial hydrostatic pressure (mm Hg)
πc = Capillary oncotic pressure (mm Hg)
πi = Interstitial oncotic pressure (mm Hg)
pp.167-168

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78
Q

Where are lymphatic capillaries found?

A

In the interstitial fluid, close to vascular capillaries.

p.168

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79
Q

What is edema? When/why does edema form?

A

Edema (swelling) is an increase in interstitial fluid volume. It forms when the volume of interstitial fluid (due to filtration out of capillaries) exceeds the ability of the lymphatics to return it to the circulation (which can be due to increased filtration, or impaired lymphatic drainage).
p.168

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80
Q

What can cause impaired lymphatic drainage?

A

Surgically removed lymph nodes (in malignancy), in filariasis (a tropical disease caused by the presence of filarial worms, especially in the lymph vessels where heavy infestation can result in elephantiasis), parasitic infection of lymph nodes, or lack of muscular activity (e.g. long plane flights, soldiers standing at attention).
p.168

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81
Q

What accounts for the inter-organ differences in blood flow?

A

Differences in vascular resistance

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82
Q

What is the basic concept of active hyperemia?

A

That blood flow to an organ is proportional to its metabolic activity
p.169

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83
Q

What are the effects of histamine and bradykinin?

A

The both simultaneously cause dilation of arterioles and constriction of venules, with the net effect being large increase in Pc, which increases capillary filtration and causes LOCAL EDEMA
p.171

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84
Q

What is the role and effect of serotonin?

A

Released in response to blood vessel damage and causes LOCAL VASOCONSTRICTION

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85
Q

Describe the effects of four different prostaglandins

A
  1. ) Prostacyclin: Vasodilator in many vascular beds.
  2. ) Prostaglandin-E series: Vasodilator in many vascular beds.
  3. ) Thromboxane A2: Vasoconstriction.
  4. ) Prostaglandin-F series: Vasoconstriction.
    p. 171
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86
Q

For angiotensin II and vasopressin, give the receptors and action/effects

A

Both act via V1 receptors and are potent vasoconstrictors that increase TPR.

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87
Q

Blood flow through coronary circulation is controlled almost entirely by what? Give examples.

A

LOCAL METABOLITES, e.g. hypoxia and adenosine. Sympathetic innervation plays only a minor role.

88
Q

At rest, blood flow to skeletal muscle is regulated primarily by what?

A

Sympathetic innervation

89
Q

The local vasodilator substances in skeletal muscle are what (3)?

A

Lactate, adenosine, and K+

90
Q

Pulmonary circulation is mainly regulated by what? What is its effect?

A

O2 –> hypoxia causes vasoconstriction in order to shunt blood AWAY from poorly ventilated areas where blood flow would be “wasted.”
p.172

91
Q

What is the myogenic hypothesis?

A

The myogenic hypothesis states that when vascular smooth muscle is stretched, it contracts…i.e. arterioles contract in response to increased BP. The converse is also true…if arterial BP suddenly decreases, they will relax and cause arteriolar resistance to decrease.
p.170

92
Q

What is active hyperemia?

A

It states that the blood flow to an organ is proportional to its metabolic activity.
p.169

93
Q

What is reactive hyperemia?

A

It is an increase in blood flow in response to OR reacting to a PRIOR PERIOD of decreased blood flow.
p.169

94
Q

What is the Metabolic hypothesis?

A

It states that O2 delivery to tissue can be matched to O2 consumption of the tissue by altering the resistance of the arterioles by producing various vasodilator metabolites.

95
Q

Name 5 vasodilator metabolites.

A

CO2, H+, K+, lactate, adenosine

96
Q

The principal function of sympathetic innervation to the skin is for what?

A

Regulation of body temperature

p.172

97
Q

During exercise, what happens to the sympathetic centers controlling cutaneous blood flow?

A

They are inhibited in order to produce VASODILATION in cutaneous arterioles so that warm blood from the body core can be shunted to the skins surface for dissipation of heat.
p.172

98
Q

Local vasodilator metabolites have _____ effect on cutaneous blood flow

A

Little effect

99
Q

Trauma to the skin causes the release of ______, which does what (3)?

A

Histamine, which produces a triple response in the skin:

  1. ) A red line
  2. ) A red flare
  3. ) A Wheal –> local edema (from dilated arterioles and constricted veins –> these two produce increased Pc, increased filtration, and local edema)
100
Q

Blood flow to skeletal muscle is controlled by what (2)? Explain.

A

Local metabolites: e.g. O2, CO2, H+, pH, etc.
Sympathetic innervation: alpha-1 receptors, activated by norepinephrine (vasoconstricting), ß-2 receptors, activated by epinephrine (vasodilating)

101
Q

Which vascular state (dilated or constricted) predominates in skeletal muscle and why?

A

Vasoconstriction because norepinephrine, released from sympathetic adrenergic neurons, stimulates primarily alpha-1 receptors (parasympathetic, i.e. rest-and-relaxation).
p.172

102
Q
  1. ) What does it mean to be thermogenic?

2. ) Give an example of a thermogenic compound

A
  1. ) Thermogenic: Actions on target tissues result in heat production
  2. ) Thyroid hormones
    p. 173
103
Q

Name the major actions of thyroid hormone (4)

A
  1. ) Stimulation of Na+/K+ ATPase
  2. ) Increased O2 consumption
  3. ) Increased metabolic rate
  4. ) Increased heat production
104
Q

Give examples of HYPOthyroid causes (2) and their general effects

A

Graves disease, thyroid tumor.

Hypothyroid: increased metabolic rate, increased O2 consumption, increased heat production.

105
Q

Give examples of HYPERthyroid causes (3) and their general effects

A

Thyroiditis, surgical removal of thyroid, iodine deficiency.
HYPERthyroid: Decreased metabolic rate, decreased O2 consumption, decreased heat production, extreme sensitivity to cold.
p.173

106
Q

Mechanisms for dissipating heat are coordinated in the ________. It is regulated by doing what?

A

Anterior hypothalamus: Increases in body temp DECREASES sympathetic activity in the skin blood vessels.
p.173

107
Q

_____ produce fever by _______.

A

Pyrogens produce fever by increasing the hypothalamic set-point
p.175

108
Q

Fever can be reduced by ______, which inhibits the _____ enzyme (which does what?).

A

Aspirin, which inhibits the cyclooxygenase enzyme (necessary for synthesis of prostaglandins)
p.174

109
Q

Cardiac output cannot increase without a concomitant _______

A

Increase in venous return

p.175

110
Q

During sympathetic action on skin vasculature, constriction occurs via ______

A

Alpha-1 receptors

p.175

111
Q

During exercise, a higher-than-normal percentage of increased cardiac output will perfuse the exercising skeletal muscle because of ________. What is the overall effect?

A

Local metabolic responses, i.e. local metabolites produce vasodilation (in the skeletal muscle).
The overall effect is DECREASED TPR (even though other vascular beds are constricted).
p.176

112
Q

When blood volume decreases, mean systemic pressure ______, and the vascular function curve shifts to the ______.

A

Mean systemic pressure decreases.
Vascular function curve shifts to the left.
p.177

113
Q

Baroreceptors in the carotid sinus detect changes in Pa and relay the information to the _____ via the ______

A

To the MEDULLA via the CAROTID SINUS NERVE

114
Q
  1. ) What are the four autonomic responses to hemorrhage?
  2. ) Via which general mechanism?
  3. ) What is the ultimate goal of these responses?
A
  1. )
    a. ) Increased heart rate
    b. ) Increased contractility
    c. ) Increased TPR (sparing the coronary and cerebral vascular beds)
    d. ) Constriction of veins (which reduces unstressed volume, increases venous return, and increases stressed return).
  2. ) General mech: Increased sympathetic outflow to heart and blood vessels, decreased parasympathetic outflow to the heart.
  3. ) Increase Pa
    p. 178
115
Q

Describe the effects of venous constriction on venous return and cardiac output.

A

Increased venous return and cardiac output.

p.178

116
Q

Describe the two main effects of Angiotensin II

A
  1. ) Arteriolar vasoconstriction, thus increasing TPR
  2. ) Stimulates secretion of aldosterone, which circulates to the kidney and causes increased reabsorption of Na+ (and therefore increases ECF, blood volume, and stressed volume)
    p. 179
117
Q

What are the effects of hemorrhage on capillaries?

A

ABSORPTION –> Decrease in capillary hydrostatic pressure (Pc), which opposes filtration out of the capillary and FAVORS ABSORPTION.
p.179

118
Q

What are the effects of hemorrhage on capillaries?

A

ABSORPTION –> Decrease in capillary hydrostatic pressure (Pc), which opposes filtration out of the capillary and FAVORS ABSORPTION.
p.179

119
Q

ADH is secreted in response to decreases in _______, mediated by ______ receptors in the ______.

A

Responds to decreases in blood volume
Mediated by VOLUME receptors in the ATRIA
p.179

120
Q

When a person moves from a supine to a standing position, blood ________

A

Pools in the veins of the lower extremities

p.179

121
Q

When a person moves from a supine to a standing position, blood ________

A

Pools in the veins of the lower extremities

p.179

122
Q

What is the effect of venous pooling in the legs on cardiac output and Pa?

A

Decrease in both cardiac output and Pa

p.180

123
Q

What is the effect of venous pooling in the legs on cardiac output and Pa?

A

Decrease in both cardiac output and Pa

p.180

125
Q

What is the effect of venous constriction on unstressed volume and venous return?

A

Decreased unstressed volume, increased venous return.

p.181

126
Q
  1. ) Activation of β1 receptors (e.g. by _______) in the SA node produces an increase in If, which increases the rate of ____________.
  2. ) In addition, there is an increase in _____, which means there are more functional ________ and thus less depolarization is required to reach threshold (i.e. threshold potential decreases).
A
  1. ) -e.g. by NE
    - increases the rate of phase 4 depolarization.
  2. ) an increase in ICa
    - more functional Ca2+ channels
    p. 136
127
Q

Give the AP correlations for the following part of the ECG: • P-wave
• PR interval
• QRS complex
• T-wave

A 
• P-wave: Atrial repolarization.
• PR interval: SA to AV node
• QRS complex: Ventricular depolarization.
• T-wave: Ventricular repolarization.
p.138
128
Q

Increases in conduction velocity through the AV node have what affect on the PR interval (e.g. due to _______ stimulation).

A

Decrease the PR interval, e.g. due to sympathetic stimulation.
p.139

129
Q

Decreases in conduction velocity through the AV node have what affect on the PR interval (e.g. due to _______ stimulation).

A

Increase the PR interval, e.g. due to parasympathetic stimulation.
p.139

130
Q

How is heart rate measured? (i.e. by counting what?)

A

Measured by counting the number of QRS complexes per minute.
p.140

131
Q
  1. ) What defines cycle length?

2. ) Based on this –Heart rate = ?

A
  1. ) Cycle length is the R-R interval (the time between one R wave and the next).
  2. ) Heart rate = 1/Cycle length
    p. 140
132
Q

Describe the speed and ionic basis of activation for APs within –

  1. ) Atrial and ventricular myocytes
  2. ) Nodal cells
A
  1. ) Atrial and ventricular myocytes express a fast AP that rises rapidly during INa activation.
  2. ) Nodal cells express slow APs that rely on ICa to provide the upstroke.
    p. 380 Lipp
133
Q

Stimulation of the sympathetic nervous system has a _______ inotropic effect on the myocardium (i.e. _______ contractility). Circulating _______ have the same effect.

A
  • positive inotropic effect, i.e. increased contractility.
  • circulating catecholamines
    p. 141
134
Q
  1. ) What are the three most important effects of a positive inotrope? Elaborate on the implications (one of them in particular).
  2. ) Which receptor type and mechanism mediates this effect?
A

1.) INCREASES rate of tension development, peak tension, and RATE OF RELAXATION.
• Faster relaxation means that the contraction (twitch) is shorter, allowing more time for refilling.
2.) This effect, like the sympathetic effect on heart rate, is mediated via activation of β1 receptors, which are coupled via a Gs protein to adenylyl cyclase.
-Activation of adenylyl cyclase leads to the production of cyclic adenosine monophosphate (cAMP), activation of protein kinases, and phosphorylation of proteins that produce the physiologic effect of increased contractility
p.142

135
Q
  1. ) What is responsible for drawing Ca2+ back into the SERCA?
  2. ) Through what mechanism is this effect achieved?
A

1.) Phospholamban
2.) Phospholamban increases Ca2+ ATPase activity when it is phosphorylated by protein kinases after ß1 stimulation.
L22, #21

136
Q

What are the two effects of increased Ca2+ uptake into SERCA?

A
  1. It causes faster relaxation (i.e. briefer contraction).
  2. It increases the amount of stored Ca2+ for release on subsequent beats.
    p. 142
137
Q

Give two reasons why contractility increases with heart rate (known as the __________ effect).

A
  • Collectively known as the Bowditch or Treppe effect*
    1. When heart rate increases, there are more action potentials per unit time and an increase in the total amount of trigger Ca2+ that enters the cell during the plateau phases of the action potentials. Furthermore, if the increase in heart rate is caused by sympathetic stimulation or by catecholamines, then the size of the inward Ca2+ current with each action potential also is increased (Recall –The mechanism of the sympathetic effect is increased ICa).
    2. Because there is greater influx of Ca2+ into the cell during the action potentials, the sarcoplasmic reticulum accumulates more Ca2+ for subsequent release (i.e. increased stored Ca2+). Again, if the increase in heart rate is caused by sympathetic stimulation, then phospholamban, which augments Ca2+ uptake by the sarcoplasmic reticulum, will be phosphorylated, further increasing the uptake process.
      p. 142
138
Q

Explain the Bowditch Staircase/Positive staircase effect

A

The very first beat after the increase in heart rate shows no increase in tension because extra Ca2+ has not yet accumulated. On subsequent beats, the effect of the extra accumulation of Ca2+ by the sarcoplasmic reticulum becomes evident. Tension rises stepwise, like a staircase: With each beat, more Ca2+ is accumulated by the sarcoplasmic reticulum, until a maximum storage level is achieved.
p.142

139
Q
  1. ) What is the effect of cardiac glycosides? Give three examples of glycosides.
  2. ) What are their general mechanisms of action (2)?
A
  1. ) Positive inotrope.
    i. ) Digoxin (from foxglove plant).
    ii. ) Digitoxin
    iii. ) Ouabain
  2. ) (i)They inhibit Na+/K+ ATPase, thereby increasing INTRAcellular Na+.
    (ii) They also DECREASE the effectiveness of the Ca2+/Na+ Exchanger, thereby increasing the INTRAcellular Ca2+.
  • Increasing intracellular Na+ and Ca2+ inside cell = More calcium = MORE CONTRACTILITY*
    pp. 142-143, #25
140
Q

Myocyte tension is directly proportional to intracellular _______ concentration.

A

Ca2+

p.144

141
Q

Congestive heart failure (CHF) is a condition characterized by _______________ (i.e. _______ inotropism).

A
  • decreased contractility of ventricular muscle
  • negative inotropism
    p. 144
142
Q
  1. ) Preload for the left ventricle is _________, or __________ – that is, preload is the ________ from which the _______.
  2. ) Afterload for the left ventricle is the ________.
A
  1. ) left ventricular end-diastolic volume, or end-diastolic fiber length – that is, preload is the resting length from which the muscle contracts.
  2. ) aortic pressure
    p. 145
143
Q

The velocity of shortening of cardiac muscle is maximal when afterload is _______, and velocity of shortening decreases as ________.

A
  • afterload is zero
  • afterload increases
    p. 145
144
Q
  1. ) What is ejection fraction?

2. ) What is the normal ejection fraction? Show how percentage is arrived at using mL of end-diastole and end-systole.

A

1.) Percentage of left ventricular end-diastolic volume (LVEDV) ejected.
2.) • End diastole 120mL – End Systole 50mL = 70mL
• 58% is ejected (normal is 55-70%)
#34

145
Q

What is cardiac output (CO)?

A 
Cardiac Output: Stroke Volume x Heart Rate = L/min output. 
#34
146
Q

State the Frank-Starling Relationship in three different ways and give correlations.

A
  1. ) The volume of blood ejected by the ventricle depends on the volume present in the ventricle at the end of diastole.
  2. ) The volume of blood the ventricle ejects in systole is determined by the end-diastolic volume.
  3. ) The volume present at the end of diastole, in turn, depends on the volume returned to the heart, or the venous return – Therefore, stroke volume and cardiac output correlate directly with end-diastolic volume (or right atrial pressure) , which correlates with venous return.
    pp. 146-147
147
Q

Give the analogous physical manifestation of the following terms:

  1. ) Preload (2)
  2. ) Afterload (1)
A
  1. ) venous return or end-diastolic volume
  2. ) aortic pressure
    p. 148
148
Q

Preload is increased because _______ is increased, which increases _______ volume

A
  • venous return
  • end-diastolic
    p. 148
149
Q

Give the equation for cardiac work/stroke work. Define variables.

A

Stroke volume x Aortic pressure
Where aortic pressure = FORCE, and stroke volume = DISTANCE.
pp.148-149

150
Q

What corresponds to left ventricular work on the pressure-volume loop?

A

The work of the left ventricle can also be thought of as the area within the pressure-volume loop
p.149

151
Q

If all else remains constant, anything that increases left ventricular end-diastolic volume (pre-load) will increase ________.

A 
Cardiac output (CO). 
#7
152
Q

What three things does increased pre-load increase?

A 
Increased pre-load = increased SV, CO, and work. 
#9
153
Q

Increases in ________ (due to an increase in _______ and/or an increase in _______) or increases in _______ will increase the work of the heart.

A
  • cardiac output (due to an increase in stroke volume and/or an increase in heart rate)
  • increases in aortic pressure
    p. 149
154
Q
  1. ) What does the Law of Laplace state?

2. ) Give formula

A

1.) It states that pressure correlates directly with tension and wall thickness and correlates inversely with radius.
2.) T = P x r
T = tension
P = pressure
r = radius
p.149, #15

155
Q
  1. ) The fourth heart sound (S4), not normally heard in adults, would be heard under what pathological condition?
  2. ) Treatment?
A
  1. ) Left ventricular hypertrophy (decreased ventricular compliance) and/or HTN.
  2. ) No extra therapy (beyond HTN treatment).
    p. 150, #23
156
Q

________ delays closure of the pulmonic valve and causes ___________ heart sound; that is, during ______, the ________ closes distinctly after the ________.

A
  • Inspiration delays closure of the pulmonic valve
  • splitting of the second heart sound
  • during inspiration
  • the pulmonic valve closes distinctly after the aortic valve.
    p. 153
157
Q
  1. ) The presence of S3 in adults indicates _________, as in ________ or advanced ______ or _________.
  2. ) Does it need treatment?
A
  1. ) -indicates volume overload
    - congestive heart failure (CHF) or advanced mitral or tricuspid regurgitation.
  2. ) Treatment required.
    p. 153, #23
158
Q

If present, what is causing the the sound heard in the fourth heart sound (S4)?

A

The sound is caused by the atrium contracting against, and trying to fill, a stiffened ventricle.
p.150

159
Q

Increases in heart rate reduce the time interval before the next _____ wave (i.e. the next cycle) and reduce, or even eliminate, the ____________ (________).

A
  • P wave
  • final portion of ventricular filling (diastasis).
    p. 153
160
Q
  1. ) One of the most important factors determining cardiac output is ________ volume. Why?
  2. ) This depends on what?
  3. ) Which pressure does #2 determine?
A
  1. ) Left ventricular end-diastolic volume; because you can only eject what/as much as is in the heart at the end of diastole.
  2. ) Venous return
  3. ) Right atrial pressure
    p. 153, L24 – #3
161
Q

What is the effect of slowing HR on CO?

A

doesn’t decrease CO because there is more time for filling.

162
Q
  1. ) Venous constriction _______ “unstressed” volume and _______ compliance.
  2. ) Shift of blood to “stressed” volume does what to BP?
A
  1. ) -DECREASES “unstressed” volume
    - decreases compliance
  2. ) HIGHER BP.
163
Q

Decreased right atrial pressure increases ________.

A 
Increases venous return to the heart – VOLUME of return, NOT PRESSURE. 
#13
164
Q

How do the following affect CO and RAP:

  1. ) Increased BV
  2. ) Decreased BV
  3. ) Increased venous compliance
  4. ) Decreased venous compliance
A
  1. ) cardiac output is increased and right atrial pressure is increased.
  2. ) cardiac output is decreased and right atrial pressure is decreased.
  3. ) cause a shift of blood into the unstressed volume and out of the stressed volume –cardiac output is decreased and right atrial pressure is decreased.
  4. ) cause a shift of blood out of the unstressed volume and into the stressed volume –cardiac output is increased and right atrial pressure is increased.
    p. 157
165
Q

What effect does increased TPR have on CO? How?

A

Increased TPR increases arterial pressure. Increase in arterial pressure produces an increase in afterload on the heart, which decreases cardiac output.
p.158

166
Q
  1. ) What are the two baroreceptors (and their CN) and what do they sense?
  2. ) What is the strongest stimulus for for a baroreceptor?
A

1.) • Carotid (CN IX – Glossopharyngeal –to medulla) sense high and low BP.
• Aortic (CN X –Vagus) mostly high BP.
2.) A RAPID CHANGE IN ARTERIAL PRESSURE.
p.159

167
Q

The sensitivity of peripheral chemoreceptors to hypoxia increases with what two changes?

A 
increased pCO2 or decreased pH.
#4, p.164
168
Q

Describe the Cushing reaction, what it is responding to, and what the result is.

A

When intracranial pressure increases (e.g. tumors, head injury), there is compression of cerebral arteries, which results in an immediate increase in PCO2 and a decrease in pH because CO2 generated from brain tissue is not adequately removed by blood flow.
• The medullary chemoreceptors respond to these changes in PCO2 and pH by directing an increase in sympathetic outflow to the blood vessels.
○ The overall effect of these changes is to increase TPR and dramatically increase Pa.
○ Leads to HTN and bradycardia (#9).
p.165

169
Q

What is ANP, i.e. what does it respond to and how?

A

Atrial Natriuretic Peptide (ANP): Responds to increased atrial pressure.
• Makes you get rid of Na+ and H2O.
• Vasodilates and decreases TPR.
p.165

170
Q

What is the Bainbridge reflex? How does it differ from arterial responses?

A

Bainbridge Reflex: An increase in heart rate (and thus, CO) in response to an increase in pressure at the venous low-pressure receptors.
• Whereas an increase in pressure at the arterial high-pressure receptors produces a decrease in heart rate (trying to lower arterial pressure back to normal).
p.166

171
Q
  1. ) In capillary exchange, the magnitude of fluid movement is determined by the ________, __ (i.e. _________), of the capillary wall.
  2. ) What, if anything, can change this parameter?
A
  1. ) hydraulic conductance, Kf (water permeability)
  2. ) Kf is not influenced by such factors as changes in arteriolar resistance, hypoxia, or buildup of metabolites. HOWEVER, Kf is increased in capillary injury (e.g., toxins or in burns). Such increases in Kf will increase the capillary permeability to water and also will result in the loss of protein from the capillary.
    p. 167
172
Q
  1. ) What does the variable Pc stand for and what does it mean?
  2. ) What is it determined by?
  3. ) What is it most affected by?
  4. ) Where is its value the greatest?
A
  1. ) Pc = Capillary hydrostatic pressure (mm Hg): A force favoring filtration out of the capillary.
  2. ) The value for Pc is determined by both arterial and venous pressures (the capillary being interposed between the arteries and veins), although the value for Pc is closer to arterial pressure than to venous pressure.
  3. ) Pc is more affected by changes in venous pressure than by changes in arterial pressure (probably because the veins will move more blood).
  4. ) Except in glomerular capillaries, Pc declines along the length of the capillary because of the filtration of fluid. Therefore, Pc is highest at the arteriolar end of the capillary and lowest at the venous end.
    p. 167
173
Q

Which would cause a greater increase in filtration: An increase in Pc via increased venous or arterial pressure?

A

Increased VENOUS pressure…but I don’t know why.

p.168

174
Q

Lymph channel should have _______ pressure.

A

negative pressure

175
Q

Which organ(s) receive the entire cardiac output?

A

Just the LUNGS.

p.169

176
Q

Changes in blood flow to an individual organ are achieved by altering ________.

A

altering arteriolar resistance

p.169

177
Q
  1. ) More autoregulation of an organ means the organ is what?i.e. ___________________.
  2. ) Give example of three organs with MAXIMUM autoregulation.
A

1.) more important, i.e. that organ can take flow from another organ when it needs it.
2.) Heart (coronary), brain (cerebral), kidney (renal).
#7

178
Q

Local control of blood flow is exerted through the direct action of ___________________.

A

local metabolites on arteriolar resistance.

p.169

179
Q

Neural and hormonal regulation is the opposite of _________.

A

AUTOREGULATION

180
Q

1.) What is the affect of K+ on on smooth muscle cells? 2.) What increases [K+]?

A

1.) High [K+] hyperpolarizes smooth muscle and prevents depolarization. Thus, K+ produces relaxation and dilation (hyperpolarization).
2.) Muscle contraction increases [K+].
#16

181
Q

How does ATP consumption dilate skeletal muscle?

A 
ATP consumption creates –More ADP, more cAMP, and more IP3. This ORGANIC PHOSPHATE DILATES SKELETAL MUSCLE. 
#15
182
Q

In the pulmonary circulation, hypoxia causes _________. Explain.

A

Hypoxia causes VASOCONSTRICTION in pulmonary circulation.

  • Regions of hypoxia in the lung cause local vasoconstriction, which effectively shunts blood away from poorly ventilated areas where the blood flow would be “wasted” and toward well-ventilated areas where gas exchange can occur.
    p. 172
183
Q
  1. ) ______ dilates cerebral vasculature the most, as does _______.
  2. ) ________ constricts pulmonary vasculature the most.
  3. ) ________ dilates coronary circulation the most, as does ________.
  4. ) ________ dilates skeletal muscle the most, as does _________.
A

1.) CO2, as does ACID (low pH).
2.) Hypoxia.
3.) Hypoxia, as does ADENOSINE.
4.) Lactate, as does K+.
#25

184
Q

______ and ______ dilate cerebral vessels. Thus, _________ constricts cerebral vessels and is the fastest way to treat cerebral hematoma.

A
  • CO2 and acid dilate cerebral vessels.

- HYPERventilation

185
Q

Which SNS receptors control the following:

  1. ) Skin
  2. ) Skeletal muscle a.) At rest, and b.) on exertion.
A

1.) Skin is ALL ALPHA-1
2.) Skeletal muscle is ALPHA-1 at rest, and ß2 on EXERTION.
#26

186
Q

The density of sympathetic innervation varies widely from tissue to tissue. For example, blood vessels of the _______ and ________ have a high density of sympathetic nerve fibers, whereas _______, _______, and _______ vessels have little sympathetic innervation.

A
  • skin and skeletal muscle
  • coronary, pulmonary, and cerebral vessels have little sympathetic innervation.
    p. 170
187
Q

What are the effects of the following on the vasculature:

  1. ) Histamine and Bradykinin (2)
  2. ) Serotonin
  3. ) Prostaglandins
  4. ) Prostacyclin
A

1.) Dilate arterioles, constrict venules.
2.) Vasoconstriction.
3.) Variable, but mostly dilatory.
4.) Dilates pulmonary vasculature.
#27

188
Q

Explain the O2 saturation of coronary arteries and veins.

A

Coronary arteries have the highest O2 EXTRACTION, therefore, coronary VEINS (e.g. coronary sinus) have the LOWEST O2 SATURATION.
-Fischer?

189
Q
  1. ) At rest, blood flow to skeletal muscle is regulated primarily by its _____________.
  2. ) Exertion regulation? By what (3)? Effects?
A
  1. ) sympathetic innervation (Alpha-1)
  2. ) Autoregulation –β2 receptors on the vascular smooth muscle of skeletal muscle are activated by epinephrine and cause vasodilation, decreased resistance, and increased blood flow.
    - Autoregulation via LACTATE, K+, and ADENOSINE.
    p. 172
190
Q

What is the major difference between Epi and NorEpi?

A 
ß2 stimulation: Nor does not have major stimulatory effects on ß2 receptors. 
-Nor vasoconstricts through Alpha-1 stimulation.
-Epi vasodilates through ß2 stimulation. 
#31
191
Q
  • Norepinephrine vasoconstricts through ______ stimulation.
  • Epinephrine vasodilates through _______ stimulation.
A

-Alpha-1 stimulation.
-ß2 stimulation.
#31

192
Q

Where is norepinephrine made?

A 
At the adrenal medulla, presynaptic neurons, and the CNS. 
#33
193
Q

What is the best treatment for people who are chronically hypoxic (e.g. COPD)? Why?

A

Low flow O2 in people who are chronically hypoxic, because it prevents death from pulmonary hypertension.
-This is because, in contrast to other tissues, the lungs constrict in areas of hypoxia in order to shunt blood to areas that are more well-perfused with O2.

194
Q

The body is coldest in the _____ (≈ time?) –Warmest in the _______ (≈ time?).

A
  • morning (≈6am)

- evening (≈6pm)

195
Q
  1. ) Normal body temperature = _____ ± ____˚C (____ ± ____˚F)
  2. ) The rectum is hotter or colder? By how much?
A
  1. ) 36.8 ± 0.4˚C (98.2 ± 0.7˚F)

2. ) The rectum is hotter –0.6˚C or 1˚F hotter.

196
Q

Exposure to cold temperatures activates _________.

A

thyroid hormones.

p.173

197
Q

Regarding menses, indicate when the female is warmer and colder –before or after ovulation.

A

-Colder BEFORE OVULATION.
-Warmer AFTER OVULATION.
#3

198
Q

What is the coldest male body part?

A 
The SCROTUM
#4
199
Q

List three antipyretics and what they target.

A 
Aspirin, NSAIDS, Acetaminophen: Targets PGE2. 
#5
200
Q
  1. ) Cold environmental temperatures activate the ________ nervous system.
  2. ) One consequence of this activation is stimulation of __ receptors in ______, which increases ______ and _______.
A
  1. ) activate the sympathetic nervous system
  2. ) β receptors in brown fat, which increases metabolic rate and heat production.
    p. 173
201
Q

Cold temperatures directly turn on what four things?

A 
Catecholamines, cortisol, growth hormone, glucagon. 
#9
202
Q

Catecholamines work much better with _______. What is this phenomenon called?

A 
Thyroxine (T4) – PERMISSIVE EFFECT. 
#9
203
Q

In the shivering mechanism, cold activates the _______, which then activates ______ and ______ ________ innervating skeletal muscle, which then produces shivering.

A
  • posterior hypothalamus
  • alpha and gamma motoneurons innervating skeletal muscle.
    p. 173
204
Q

Mechanisms for dissipating heat are coordinated in the ____________. Increased body temperature decreases ________ in skin blood vessels. What effect does this have?

A
  • anterior hypothalamus
  • decreases sympathetic activity –dilates vessels and increases blood flow at the surface = heat dissipation.
    p. 173, #11
205
Q

Give a method of bodily heat dissipation apart from blood shunting.

A

Sympathetic cholinergics – SWEAT.

206
Q

_______ produce fever by increasing the _________.

A
  • Pyrogens
  • by increasing the hypothalamic set-point temperature.
    p. 174
207
Q

Give the mechanism for fever production

A

At the cellular level, the mechanism of pyrogen action is increased production of interleukin-1 (IL-1) in phagocytic cells.
• IL-1 then acts on the anterior hypothalamus to increase local production of prostaglandins (PGE2), which increase the set-point temperature.
p.174

208
Q

________ makes prostaglandins.

A 
Cyclooxygenase
#13
209
Q

What can cause heat exhaustion? What are some characteristics (sweating, hydration, mental status)?

A

Can occur as a consequence of the body’s responses to elevated environmental temperature.
• If the sweating is excessive, it can result in decreased ECF volume (SEVERE THIRST RESULTS), decreased blood volume, decreased arterial pressure, and fainting.
Normal mental status.
p.174

210
Q

What is affected with heat cramps? What are they distinguished by?

A

Big muscle groups affected –No muscle degeneration.

Distinguish by…is body temp normal, you can sweat, is there a normal mental status.

211
Q

Heat stroke occurs when body temperature increases to the point of ________. There is often elevated ____________ due to ___________.
Treatment?

A

-to the point of tissue damage.
-creatinine kinase due to muscle degeneration.
-Treat with evaporative cooling (spray them down), intravenous fluids.
#16

212
Q
  1. ) In genetically predisposed individuals, malignant hyperthermia can be caused by an idiosyncratic reaction to _________.
  2. ) Give three symptoms of malignant hyperthermia.
A
  1. ) inhalation anethestics
  2. ) Masseter muscle rigidity – muscle rigidity, elevated creatinine kinase, high pCO2.
    p. 174, #17
213
Q
  1. ) What three vasculatures does exercise dilate?

2. ) Where does selective arteriolar constriction occur during exercise (5)?

A

1.) Exercising skeletal muscle, coronary, cerebral.
2.) Skin, spleen, GI tract, kidney, inactive muscles.
#20

214
Q

What mediates the local metabolic response in exercising skeletal muscle? via what substances (3)? What is the ultimate effect?

A 
Active hyperemia –via Lactate, adenosine, K+ – Cumulative effect is DECREASED TPR. 
#21, p.175
215
Q

What are the manifestations in anterior leads as a result of increased SNS outflow during a stroke?

A

Deep T-wave inversions

L29, #15

216
Q

When a person moves from a supine to a standing position, blood pools in _________. What allows this to happen?

A
  • the veins of the lower extremities
  • The capacitance of the veins allows for large blood volumes to accumulate.
    p. 179
217
Q

The primary compensatory cardiovascular response to the decrease in mean arterial pressure involves the _________.

A

baroreceptor reflex

p.180

218
Q

The _______ artery (Swan-Ganz) catheter allows direct, simultaneous measurement of which four pressures?

A

-pulmonary artery (Swan-Ganz) catheter
-right atrium, right ventricle, pulmonary artery, and the filling pressure (“wedge” pressure) of the left atrium.
#25

Physiology (5 decks)

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