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Bio 465 - Physio > Chapter 14 - Cardiac Output, Blood Flow, Blood Pressure > Flashcards

Chapter 14 - Cardiac Output, Blood Flow, Blood Pressure Flashcards

1
Q

Volume of blood ejected per beat is ….

A

Stroke volume

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2
Q

Cardiac rate is described as….

A

The number of beats per minute

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3
Q

What is the average resting cardiac output in an adult?

A

5.5L/min (5,500 mL)

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4
Q

How does the body compensate for the fact that - each ventricle has roughly the same cardiac output, so the lungs receive the same amount of blood as the entire body…

A

The arteriole resistance in the pulmonary system is much lower than the systemic system. 10-20 mmHg in pulmonary compared to 70-105 mmHg systemic

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5
Q

What is the total blood volume, in most adults?

A

5.5 L (so each ventricle pumps the equivalent of the total blood volume each minute under resting conditions!)

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6
Q

Parasympathetic stimulation effect on SA Node -

Sympathetic stimulation effect on SA Node -

A
  • Parasympathetic - decreases rate of pacemaker potentials
  • Sympathetic - increases rate of pacemaker potentials
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7
Q

ACh binds to which type of cholinergic receptors to open [] channels diffusing outward, partially countering the depolarization that produces pacemaker potentials

A

Muscarinic

K+ channels

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8
Q

Mechanisms that affect the cardiac rate are said to be -

A
  • Chronotropic
    • positive chronotropic effect - increases cardiac rate
    • Negative chronotropic effect - decreases cardiac rate
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9
Q

Autonomic Innervation of the heart is coordinated by which area of the brain stem?

What is 1 example of a sensory receptor that will send signals to these higher brain areas? Where are these receptors located?

A

Cardiac Control Center in the medulla oblongata of the brain stem.

Baroreceptors - in the aorta and carotid arteries.

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10
Q

What are the three variable that regulate stroke volume?

A
  1. End Diastolic Volume (EDV) - volume of blood in ventricles at the end of diastole
  2. Total Peripheral Resistance - frictional resistance, or impedance to blood flow in the arteries
  3. Contractility - strength of ventricular contraction
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11
Q

What is the “Frank-Starling Law of the heart?”

A

The relationship between stroke volume and preload: An increase in EDV results in an increase in stroke volume. (intrinsic property)

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12
Q

The stroke volume is inversely proportional to the total [] resistance; If [] resistance is higher, the stroke volume will be lower.

A

peripheral

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13
Q

Normally, contraction strength can eject [] to [] mL of blood out of a total EDV of 110-130 mL

A

70-80 mL

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14
Q

Why does stretching actually increase the contractile strength of ventricles? (This is not the case in skeletal muscles, remember)

A
  • At rest - myocardium are too close together. Stretching allows for more interactions between actin and myosin.
  • Stretching also increases the sensitivity of the Ca2+ release channels in the, promoting the release of Ca2+ in response to stimulation.
    • supposedly this is the main cause in the strength of stretching in myocardium vs skeletal muscle
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15
Q
A
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16
Q

How do norepinephrine and epinephrine produce a positive inotropic effect on the heart?

A
  • Since these two molecules increase cardiac rate (by causing cAMP product, which acts on HCN and Ca2+ release channels to cause more depolarizations) - this increase in Ca2+ to the sarcomeres can increase contractility
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17
Q

What are the 2 ways that the sympathoadrenal system can affect cardiac output?

A
  1. Positive inotropic effect on contractility
  2. Positive chronotropic effect on cardiac rate
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18
Q
  • The rate at which atria and ventricle are filled with venous blood depends on [] [] volume and [] pressure.
  • However, the [] pressure serves as the driving force for return of blood to the heart
A
  1. total blood volume and venous pressure
  2. venous pressure
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19
Q

Why are veins called capacitance vessels?

A
  • Veins are compliance vessels due to their ability to stretch and hold more blood (2/3 of total blood volume in veins). They are thinner and less muscular than arteries.
  • Capacitors are electrical devices that hold electricity….get it?
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20
Q

What is the mean venous pressure and mean arterial pressure?

A
  • Venous - 2 mmHg
  • Arterial - 90 to 100 mmHg
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21
Q

Quick flow chart on how factors effecting venous return affect cardiac output?

A

Venous retunr dictates the amount of EDV…which can increase/decrease stroke volume….which has a direct affect on cardiac ouptut.

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22
Q

What is the hydrostatic pressure (in mmHg) against the inner capillary walls - on the arteriolar end and the venular end?

A
  • Arteriolar end - 37 mmHg
  • Venular end - 17 mmHg
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23
Q

[] are the opposing forces that affect the distribution of fluid across the capillary…

A

Starling Forces

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24
Q

Excessive accumulation of interstitial fluid is known as….

A

edema.

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25
Q

Edema may result from these examples (im sure there are more)…

A
  1. High arterial blood pressure - causes excess filtration
  2. Venous Obstruction - produces a congestive increase in capillary pressure
  3. Leakage of plasma proteins into intersitial Fluid - causes reduced osmotic flow into capillary
  4. myxedema - excessive production of particular glycoproteins (mucin) in extracellular matrix caused by hypthyroidism
  5. Decreased plasma protein concentration - liver or kidney disease where proteins are xpelled inurin
  6. Obstruction of lymphatic drainage - due to parasitic larvae in elephantiasis.
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26
Q

How is water a diuretic?

A

It promotes urine formation. Water inhibits the release of ADH (ANTIdiuretic hormone) becuase it dilutes blood. ADH is released when blood osmolality increases.

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27
Q

Where is aldosterone secreted from? What is its function?

A

Adrenal cortex

Promotes teh reabsorption of salts by the kidneys.

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28
Q

Why does aldosterone produce a change in plasma osmolality?

A
  • It does not!
  • It only produces an increase in blood volume because it promotes the reabsorption of salt and water in proportionate amounts.
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29
Q

Which apparatus in the kidneys sense a lowered blood pressure in the renal artery and lowered amount of NaCl and water in renal filtrate?

A

Juxtaglomerular appartus

30
Q

What does the juxtaglomerular appartus do in response to lowered blood pressure, NaCl, and water in the renal artery? (give a little flow chart)

A

Releases the enzyme renin –>cleaves a plasma protein called angiotensinogen into angoitensin I –>angiotensin I goes to the lungs where angiotensin-converting enzyme (ACE) removes 2 amino acids and cleaves it into –> angiotensin II

Angiotensin II causes blood pressure to rise.

31
Q

Is Angiotensin II a powerful vasoconstrictor or vasodilator?

A

Vasoconstrictor - it increases blood pressure.

32
Q

Pressure at the Vena Cava and right atrium?

Pressure at Aorta?

Mean Arteriol Pressure (MAP)?

A
  1. 0 mmHg
  2. 100 mmHg
  3. 100 mmHg
33
Q

Resistance to blood flow through a vessel is directly proportional to the [] of the vessel and to the [] of the blood.

A
  • length
  • Viscosity
34
Q

The main physiological regulators of blood flow through an organ are…(2 things)

A
  1. Mean arterial pressure
  2. vascular resistance to flow
35
Q
  • [] provide the greatest resistance to blood flow since they are the smallest arteries and can become narrower by vasoconstriction.
  • Blood flow to an organ is thus largely determined by the vasoconstriction/vasodilation of these….
A

arterioles

36
Q

Extrinsic Regulation of blood flow refers to control by the [] and [] systems…

A

Autonomic nervous system and endocrine system. (Ex: angiotensin II)

37
Q

During fight-or-flight reaction, an incrrease in the activity of adrenergic fibers produces [] in the digestive tract, kidneys, and skin.

A

vasoconstriction

38
Q

Which is more important in the control of total peripheral resistance, parasympathetic innervation or sympathetic innervation?

A
  • Sympathetic Innervation
  • Parasympathetic causes vasodilation with cholinergic receptors so that is good. But it only really innervates the digestive tract, external genitalia, and salivary glands….
39
Q

[] mechanisms within individual organs provide a localized regulation of vascular resistance and blood flow.

A

Intrinsic

40
Q

[] refers to the ability of some organs - mainly brain and kidney - to utilize intrinsic control mechanisms to maintain a relatively constant blood flow despite wide fluctuations in blood pressure.

A

Autoregulation

41
Q

What are 4 localized chemical conditions that promote vasodilation?

A
  1. decreased oxygen concentrations
  2. increased carbon dioxide concentrations
  3. decreased tissue pH
  4. release of K+ and paracrine regulators
42
Q

Since the heart contains large amounts of myoglobin, numerous mitochondria, and aerobic respiratory enzymes….

A

it is extremely specialized for aerobic respiration

43
Q

How is blood flow extrinsicely and intrinsicely controlled in skeletal muscles?

A
  • Extrinsic
    • Resting condition - blood vessels are vasoconstricted due to sympathetic stimulation of alpha-adrenergic receptrs.
    • Fight/Flight - Epinenprhine stimulates beta-adrenergic receptors and there are cholinergic receprts that cause blood vessels to dilate.
  • Intrnisic
    • Metabolic activity - lowered pH, Higher CO2, Lower O2, Increased extracellular K+, secretion of adenson…all cause vasodilation.
44
Q

What are the three causes for an increase in blood flow to dynamically excerising muscles?

A
  1. increased total blood flow (cardiac output)
  2. Metabolic vasodilation in excercising muscles
  3. diversion of blood away from the viscera and skin
45
Q

Vascular resistance in the viscera and skin do what…

What causes this?

A

Increases - due to vasoconstriction caused by adrenergic sympathetic fiber stimulation

46
Q

What is the main factor that can increase the stoke volume (ejection fraction) in heavy exercise?

A
  • Increased contractility that results from sympathoadrenal stimulation
47
Q

Myogenic Regulatin by Brain -

  • When CO2 in the blood rises above normal levels, what happens to brain vessels?
  • When CO2 in the blood falls below normal levels, what happens to brain vessels?
A
  1. Rises - brain blood vessels vasodilate (actually due to decrease in pH)
  2. Falls - brain blood vessels vasoconstrict (causes dizziness during hyperventilation in exercise fro example)
48
Q

Which vessels regulate the blood flor to the skin during hot/cold temperatures?

A

Ordinary arterioles and arteriovenous anastomoses - these divert blood to deep venules

49
Q

When temperature is low - what happens to cutaneous blood flow?

A

Increased Sympathetic nerve stimulation to arterioles causes vasoconstriction…diverting blood to deep venules in order to keep heat internal.

50
Q

When temperature is higher, what happens to cutaneous blood flow?

A

Decreased sympathetic nerve stimulation - causing vasodilation and increased blood flow to surface of skin.

51
Q

What provides a greater resistance to blood flow, capillary or arteriole?

A

Arteriole.

They are very narrow, and the shear area of capillaries allows for a lesser resistance to blood flow.

52
Q

The most important factors affecting blood pressure are…(3 of them)

A
  1. Cardiac Rate
  2. Stroke Volume
  3. Total Peripheral Resistance
53
Q

The sympathoadrenal system can control blood pressure by -

  1. [] of arterioles (thereby [] total peripheral resistance)
  2. Promoting increased [] output
  3. Indirectly by stimulating [] of renal blood vessels and thus [] urine output
A
  1. vasoconstriction, raising
  2. cardiac
  3. constriction, decreasing.
54
Q

What are the specialized receptors for sensory blood pressure changes?

Where are the located, specifically?

A

baroreceptors

Aortic Arch and carotid sinuses

55
Q

The [] [] [] in the medulla regulates the degree of vasoconstrictin/vasodilation, and hence helps to regulate total peripheral resistance

A

vasomotor control center

56
Q

The [] [] [] in the medulla regulates the cardiac rate

A

cardiac control center

57
Q

Which ascending nerves takes sensory information from the baroreceptors to the medulla oblongata?

A
  1. Vagus (X)
  2. Glossopharyngeal (IX)
58
Q

What is the baroreceptor reflex arc?

A
  1. aortic arch and carotid sinus baroreceptors as the sensors
  2. the vasomotor and cardiac control centers of the medulla oblongata as the integrating centers
  3. parasympathetic and sympathetic axons to the heart and blood vessels as the effectors.
59
Q

[] [] helps maintain normal bnlood pressure on a beat-to-beat basis ([] are involved in long-term regulation)

A

baroreceptor reflex

Kidneys - long term

60
Q

What is the Atrial Stretch Receptor Reflex? These are located in the atria and activated by increased venous return.

A
  1. stimulate reflex tachycardia, as a result of increased sympathetic nerve activity
  2. inihibit ADH release, resulting in excertion of larger volumes of urine and lowering of blood volume
  3. promote increased secretino of atrial natriuretic peptide (ANP). lowers blood volume by increasing urinary salt and water excretion
61
Q

When the a blood pressure cuff begins to deflate, and equals systolic pressure - what occurs?

A

The first Korotkoff sound can be heard

62
Q

The last Korotkoff sound will be heard when??

A
  • The cuff pressure is equal to diastolic pressure - The sounds disappear becuase pressure is low enough for laminar flow to continue.
63
Q

Pulse Pressure =

A

systolic pressure - diastolic pressure (120/80 = 50 mmHg pulse pressure)

64
Q

Mean Arterial Pressure=

A

diastolic pressure + 1/3 pulse pressure

65
Q

What is the difference between secondary hypertension and primary (essential) Hypertension?

A
  • Secondary is casued by something “known” - renal failure, adrenal tumor etc.
  • Primary is caused by poorly understood processes and things.
66
Q

What is Hypovolemic Shock?

A

Circulatory shock that is due to low blood volume, as might be caused by hemorrhage , dehydration, or burns.

67
Q

What is Septic Shock?

A

Refers to a dangerously low blood pressure (hypotension) that may result from sepsis, or infection.

68
Q

What is Anaphylactic Shock?

A
  • rapid fall in blood pressure as a result of severe allergic reaction.
  • Results from the widespead release of histamine, which causes vasodilation and thus decreases total peripheral resistance
69
Q

What is Neurogenic Shock?

A
  • Rapid fall in blood pressure in which sympathetic tone is decreased, usually because of upper sinal cord damage or spinal anesthesia.
70
Q

What is Cardiogenic Shock?

A
  • Results from cardiac falure, as defined by a cardiac output inadequate to maintain tissue perfusion
  • Results from infarction that causes loss of a significant porportion of mypcardium

Bio 465 - Physio (16 decks)

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