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BIOM 3200 > Cardiovascular II > Flashcards

Cardiovascular II Flashcards

1
Q

Identify characteristics of arteries, veins and capillaries based on location.

A

Large Arteries: 3mm, oxygenated blood away from heart
Arteries: 100mm, oxygenated blood away from heart
Arterioles: 20-30mm, oxygenated blood away from heart
Capillaries: 7-10mm, gas exchange with surrounding tissues
Venules: 20-30mm, deoxygenated blood towards heart
Veins: 15-24mm, deoxygenated blood towards the heart
Large Veins: 6mm, deoxygenated blood towards heart

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2
Q

Identify the layers of an artery and indicate properties of each layer.

A
  1. Tunica Externa: connective tissue (collagen) to provide stability
  2. Externa Elastic Membrane: contains elastin fibres; allow for stretching when under high pressure from ventricular contraction; able to recoil driving blood through circulatory system during diastole
  3. Tunica Media: smooth muscle
  4. Internal Elastic Membrane: contains elastin fibres to allow expansion of vessel under pressure
  5. Tunica Interna: endothelium (lines lumen of blood vessel), basement membrane made of glycoprotein and connective tissue, elastin
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3
Q

Identify the layers of a vein and indicate properties of each layer.

A
  1. Tunica Externa: connective tissue
  2. Tunica Media: smooth muscle
  3. Tunica Interna: endothelium (lines lumen of blood vessel), basement membrane made of glycoprotein and connective tissue, elastin
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4
Q

Identify the layers of a capillary and indicate the properties of each layer.

A

Capillaries are made of single layer of endothelium, allowing rapid exchange between blood and tissues.

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5
Q

Describe pulse pressure of an artery and how it impacts blood flow.

A

Pulse Pressure: difference between diastolic and systolic pressure
-can be felt by pulsating artery and feeling expansion
-proportional to stroke volume as pulse pressure and stroke volume increase; difference in blood pressure becomes greater

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6
Q

Differentiate between arteries, distributing arteries and arterioles.

A

Conducting Arteries: largest and more elastic arteries
-capable of expanding to absorb pressure from ventricular contraction and recoil during relaxation
Disturbing Arteries: smaller, more muscular arteries that distribute blood to organ
Arterioles: smallest arteries, that distribute blood to capillary beds
-blood flow controlled at arteriole level by vasoconstriction and vasodilation of smooth muscle layer

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7
Q

Discuss continuous capillaries: mechanisms of exchange and where they are located in the mammalian body.

A

Continuous Capillaries: made of endothelial cells that are closely attached to each other without larger intercellular channels
-movement of very small molecules; water, gases
-exchange is mainly by pinocytosis
-located in adipose tissue, muscle, lungs, CNS (blood-brain barrier)

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8
Q

Discuss fenestrated capillaries including: mechanism of exchange and where they are located in the mammalian body.

A

Fenestrated Capillaries: larger pores ‘fenestra’, increasing exchange of substances across capillary bed
-pores lined with mucoprotein to restrict large molecules (proteins)
-located in endocrine glands, kidneys, intestines

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9
Q

Discuss discontinuous capillaries including: mechanism of exchange and where they are located in the mammalian body.

A

Discontinuous Capillaries: largest opening, for larger components (RBC, WBC, large serum proteins)
-mostly found in the liver, spleen and bone marrow

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10
Q

Describe a pre-capillary sphincter and indicate its function.

A

Pre-Capillary Sphincter: junction between arterial system and capillary beds
-made of smooth muscle at control blood flow into capillary bed by cycles of contraction and relaxation
-group of circular muscle bands that regulate blood flow from the arterioles into the capillaries

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11
Q

Differentiate between veins and venules.

A

Venules: smallest vein, have 2 layers; tunica externa and tunica interna
-contains valves
-collect deoxygenated blood from tissue capillaries and carries blood to progressively larger veins
Veins: larger, have 3 layers; tunica externa, tunica media, tunica interna
-medium veins have valves, larger veins have no valves
-collects blood from venules and delivers it back to the heart

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12
Q

Describe mechanisms that facilitate venous return to the heart.

A
  1. Skeletal Muscle Pump: contraction of surrounding skeletal muscles compresses veins and propels blood forward
  2. Venous Valves: closure of valves prevents backflow of blood
  3. Breathing: contraction of diaphragm during inspiration causes difference in pressure between abdomen (high pressure) and thoracic cavity (low pressure)
    -pressure difference helps pump blood against gravity upward towards the heart
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13
Q

Define: flow and perfusion.

A

Flow: measure of blood flowing through specific tissue in given time (mL/min)
Perfusion: measure of blood flow per given volume or tissue mass in given (mL/min/g)

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14
Q

Discuss how blood flow is affected by driving forces and resistance.

A

-blood flow is determined by pressure difference (from high to low pressure)
-resistance within vasculature is measure of how difficult it is for blood to move through vessel
-greater pressure difference, greater blood flow

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15
Q

Identify factors that determine driving forces and resistance.

A

Driving Forces: difference in pressure
Resistance: radius of blood vessel, blood viscosity, and vessel length

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16
Q

Discuss the Poiseuille’s law and relate length of vessel, viscosity of blood, and radius of vessel to resistance.

A

Poiseuille’s Law: flow is related to blood pressure difference across vascular bed, length of vessels, viscosity of blood and fourth power of vessel radius

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17
Q

Identify factors which affect blood viscosity, length of vessels, and vessel radius.

A

Vessel Radius:
-Vasoconstriction: decrease in vessel radius, increase resistance, decrease blood flow
-Vasodilation: increase vessel radius, decrease resistance, increase blood flow
Blood Viscosity:
-Dehydration - Polythemia: high RBC count due to high altitudes (blood doping) causes increase blood viscosity, increase resistance, decrease blood flow
-vessel length remains constant

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18
Q

Define mean arterial pressure.

A

Mean Arterial Pressure: average blood pressure during one cardiac cycle; major determinant of blood flow = diastolic pressure + 1/3 pulse pressure

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19
Q

Indicate average mean arterial pressure in different vessels of the systemic circulation.

A

Large Arteries: 120-80mmHg
Small Arteries/Arterioles: 100-30mmHg
Capillaries: 30-20mmHg
Venules: 20-5mmHg
Large Veins: < 5mmHg - 0

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20
Q

Define: systolic blood pressure, diastolic blood pressure, pulse pressure, hypertension and hypotension.

A

Systolic Blood Pressure: highest level of arterial blood pressure during ventricular contraction
Diastolic Blood Pressure: lowest level of arterial blood pressure during ventricular
Pulse Pressure: difference in blood pressure between systolic and diastolic blood pressure
Hypertension: chronic high resting blood pressure (>140/90)
Hypotension: chronic low resting blood pressure

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21
Q

List the factors that determine blood pressure.

A

Cardiac output, blood volume, resistance of blood flow.

22
Q

Describe how a pressure cuff and sphygmomanometer measure blood pressure.

A

-pressure cuff is wrapped around patients arm to constrict brachial artery and restrict blood flow; creates turbulent blood flow through artery causing Korotkoff sounds detected by stethoscope
-pressure within the cuff is measure by a sphygmomanometer
1. At first cuff pressure is too high so artery will be pinched off; no sound (cuff pressure>systolic pressure)
2. Gradual decrease in cuff pressure by releasing air; first Korotkoff sound is heard as blood flows through the constricted artery (systolic pressure) cuff pressure = systolic pressure
3. Continual decrease in cuff pressure until Korotkoff sounds disappear; artery is no longer constricted and return to normal blood flow
-last Korotkoff sound prior to this represents diastolic pressure (cuff pressure = diastolic pressure)

23
Q

Define cardiac output.

A

Cardiac Output: volume of blood being pumped per minute
CO (mL/min) = Stroke Volume (mL/beat) x Cardiac Rate (beats/min)

24
Q

Indicate how stroke volume and heart rate can alter cardiac output.

A

Increase in stroke volume and heart rate will increase CO

25
Q

Discuss how autonomic nervous stimulation affects pacemaker potentials of the SA node.

A

-release of epinephrine and norepinephrine from ANS; cause opening of HCN channels (through the activation of β1-adrenergic receptors and production of cAMP) on the membrane pacemaker cells of the SA node (influx of Na+) increasing rate of depolarization and firing action potentials and increase heart rate
-release of acetylcholine from the ANS causes opening of K+ channels, increasing the amount of K+ leaving pacemaker cell; slows down the rate of depolarization, decrease in heart rate

26
Q

Describe how autonomic stimulation of the heart affects HR and CO.

A

-autonomic stimulations mostly controls HR by affecting SA node
-SNS also affects muscle contraction in atria and ventricles
-SNS - increase HR, contraction strength, CO
-PNS - decrease HR, CO

27
Q

Discuss the location of cardiac control centre and how it mediates changes in HR.

A

-cardiac control centre is located in medulla oblongata of brain stem
-receives information from higher brain areas and sensory information (baroreceptors) and will regulate HR through ANS
-cardiac centre contains 2 neural pools:
1. Cardioacceleratory Centre: sends signal via SNS to increase HR
2. Cardioinhibitory Centre: sends signal via PNS to decrease HR

28
Q

Discuss how baroreceptors, chemoreceptors, and proprioceptors can influence HR through the cardiac control centre.

A

Baroreceptor, chemoreceptors and proprioceptors will send sensory information to cardiac control centre.
-Baroreceptors: pressure sensors in aorta and carotid arteries; detect increase in BP and will increase its firing rate to cardiac control centre
-Chemoreceptors: pH sensors found in aortic arch, carotid arteries and medulla oblongata; detect changes in blood pH, O2, and CO2 relays information to cardiac control centre to increase HR if pH is low due to slow removal of CO2
-Proprioceptors: receptors found in muscles and joints; sensors are activated upon start of exercise and will quickly relay information to cardiac centre to increase HR

29
Q

Define tachycardia, bradycardia, chronotropic and dromotropic.

A

Tachycardia: high resting heart rate (>100bpm)
Bradycardia: slow resting heart rate (<60bpm)
Chronotropic: mechanisms that affect HR; can either be positive or negative
Dromotropic: mechanisms that affect conduction speed

30
Q

List the 3 factors responsible for determining stroke volume.

A

Preload (end diastolic volume), afterload (total peripheral resistance), and contractility

31
Q

Define: preload, afterload, contractility, end diastolic volume, end systolic volume, ejection fraction and total peripheral resistance.

A

Preload: amount of tensions in ventricular myocardium immediately before it begins to contract
-exercise increases preload; increased venous return; stretches myocardium
-proportional to the volume of blood at the end of diastole
Afterload: amount of resistance imposed on the ventricles after the start of contraction
-blood pressure in the arteries just outside of the semilunar valves
-proportional to the total peripheral resistance
Contractility: strength of a contraction
End Diastolic Volume: volume of blood in the ventricles at the end of diastole (refilling)
End Systolic Volume: volume of blood that remain in the ventricles following ventricular contraction
Ejection Fraction: volume of blood that is ejected by left and right ventricle per heartbeat
Total Peripheral Resistance: resistance found in arterial system

32
Q

Discuss how preload and afterload can affect stroke volume and thus CO.

A

Preload: increase in venous return, cause more blood to return to heart, stretching myocytes increasing tension
-increase preload, increase stroke volume and increase in cardiac output
-decrease preload, decrease stroke volume and decrease in cardiac output
Afterload: blood is pumped from an area of high pressure to low pressure
-if the pressure in the arterial system is too high, it’s more difficult for the ventricles to pump blood due to the equalization of pressure
-increase afterload, decrease stroke volume, and decrease in cardiac output

33
Q

Describe the Frank-Starling Law of the heart.

A

Frank-Starling Law: intrinsic property of heart, end diastolic volume (EDV) is directly proportional to heart;s contraction strength and so stroke volume
-EDV increase, increase stretch of myocardium, increase tension, increase contraction of myocardium, increase stroke volume

34
Q

Describe how autonomic stimulation of the heart affects stroke volume and CO.

A

-sympathetic stimulation will increase strength of contraction of ventricles; by increasing amount of Ca2+ available to sarcomeres
-increase in contractility will increase stroke volume and so cardiac output

35
Q

Define: venous return, compliance, and capacitance vessels.

A

Venous Return: blood that is returned to the heart
Compliance: ability of veins to expand under high pressure due to thinner, less muscular walls
Capacitance Vessels: veins are compliant; they are able to store large volumes of blood known as capacitance vessels

36
Q

Identify factors that determine venous return and how that influences CO.

A

-blood volume, venous pressure (vasocontriction, skeletal muscles pump), negative intrathoracic pressure (breathing)
-increase in any of these factors, increase venous return, increase end diastolic volume, increase stroked volume, increase CO

37
Q

Define extrinsic and intrinsic regulation of blood flow.

A

Extrinsic Regulation: control of blood flow by endocrine system and ANS
Intrinsic Regulation: control of blood flow by mechanisms within heart

38
Q

Identify factors that determine intrinsic and extrinsic regulation of blood flow.

A

Extrinsic: SNS (adrenergic, cholinergic), PNS (cholinergic), hormones (ADH, histamine, prostaglandins)
Intrinsic: myogenic controls, metabolic controls

39
Q

Predict changes to blood flow, and total peripheral resistance after autonomic stimulation of peripheral vessels.

A

SNS: adrenergic (vascular smooth muscle)
-vasoconstriction of vessels, increase total peripheral resistance, decrease blood flow
SNS: chloinergic (skeletal muscle)
-vasodilation of vessels, decrease total peripheral resistance, increase blood flow
PNS: cholinergic (digestive tract, genitalia, salivary glands)
-vasodilation of vessels, increase blood flow (little to no effect on total peripheral resistance)

40
Q

Discuss the myogenic mechanism that regulates blood flow.

A

-vascular smooth muscle within organs detects changes in blood pressure; respond to either dilating or constricting blood vessels, to increase/decrease blood flow to maintain constant blood flow regardless of systemic arterial pressure
-especially important for brain and kidney

41
Q

Identify metabolic factors that can regulate blood flow.

A

Metabolic factors that signal for increased oxygen requirement, and increased blood flow:
-decrease O2, increase CO2, decrease tissue pH (due to lactic acid buildup + increase CO2), release of K+

42
Q

Describe the baroreceptor reflex.

A

Baroreceptor Reflex: maintains normal BP through system of arterial baroreceptors; detect changes in BP and relays information to ANS to regulate BP

43
Q

Identify location of baroreceptors, nerves involved and central centres responsible for mediating the baroreceptor reflex.

A

Baroreceptors are located in aortic arch and carotid sinuses.
Nerves:
1. Sensory Neurons: relay information from baroreceptors to control centres via vagus and glossopharyngeal nerves
2. Effector Neurons: sympathetic cardiac nerves/parasympathetic vagus nerves
Control/Integration Centres:
1. Vasomotor Control Centre: located in medulla oblongata and controls vasoconstriction, vasodilation
2. Cardiac Control Centre: located in medulla oblongata and regulates cardiac rate (firing of SA node)

44
Q

Predict changes in blood pressure mediated by the baroreceptor reflex after various stimuli.

A

-decrease venous return will cause a decrease in blood pressure detected by baroreceptors
-sensory neurons relay information to integration centres in the medulla oblongata that will:
1. Initiate vasoconstriction of arterioles to increase peripheral resistance
2. Increase cardiac rate, thus cardiac output
-both will cause an increase in blood pressure, turning off baroreceptor reflex through negative feedback loop

45
Q

Describe the effects of exercise on cardiac output.

A

-CO will increase 5X during exercise to meet oxygen demands and removal of waste products
-increase in CO is due to increase in stroke volume and cardiac rate
Stroke Volume:
-increase venous return due to muscle activity and increase respiratory rate/diaphragm movement (increase in preload)
-increase ejection fraction due to increase myocardial contractility (Frank-Starling Law)
-decrease afterload due to decrease total peripheral resistance (due to vasodilation in skeletal muscle)
Cardiac Rate:
-increase in sympathetic nerve activity (release of epinephrine, norepinephrine)

46
Q

Define: blood hydrostatic pressure, interstitial hydrostatic pressure, blood colloid osmotic pressure and interstitial colloid osmotic pressure.

A

Blood Hydrostatic Pressure: blood pressure within capillaries
Interstitial Hydrostatic Pressure: pressure of interstitial fluid outside of capillaries
Blood Colloid Osmotic Pressure: osmotic pressure exerted by plasma proteins within capillaries
Interstitial Colloid Osmotic Pressure: osmotic pressure exerted by proteins within interstitial fluid

47
Q

Identify the Starling forces that mediate exchange of fluid between tissue and capillaries and predict the movement of fluids for each.

A
  1. Blood Hydrostatic Pressure: increase hydrostatic pressure -> fluid movement from capillary into interstitial space
  2. Interstitial Colloid Osmotic Pressure: increase interstitial colloid pressure -> fluid movement from capillary into interstitial space
  3. Interstitial Hydrostatic Pressure: increase interstitial hydrostatic pressure -> fluid movement from interstitial space into capillary
  4. Blood Colloid Pressure: increase blood colloid osmotic pressure -> fluid movement from interstitial space into capillary
48
Q

Discuss why Starling forces favour net filtration at arterial end and net absorption at venous ends of capillaries.

A

-at arterial end of capillaries: movement of fluid favours net filtration (movement out of capillaries) due to high hydrostatic pressure
-at venous end of capillaries: blood hydrostatic pressure is lower and there is net movement of fluid into capillaries (net absorption) due to osmotic pressure of plasma proteins (blood colloid osmotic pressure)

49
Q

Identify factors that could alter the Starling forces and result in edema.

A
  1. High Arterial BP: increase hydrostatic pressure in capillaries, increase movement of fluid out of capillaries into interstitial space
  2. Venous Obstruction: increase hydrostatic pressure in capillaries, increase movement of fluid out of capillaries into interstitial space
  3. Leakage of Plasma Proteins into Interstitial Fluid: increase colloid pressure in interstitial space, increase movement of fluid out of capillaries into interstitial space
  4. Decrease in Plasma Protein: decrease colloid pressure in capillaries , decrease movement of fluid into capillaries (at venular end)
50
Q

Briefly discuss how the kidneys can regulate blood volume by anti-diuretic hormone, aldosterone and renin-angiotensin-aldosterone system, atrial natriuretic peptide.

A

Anti-diuretic hormone (ADH): low blood volume results in high blood osmolality
-detected by osmoreceptors in the hypothalamus -secretion of ADH by the posterior pituitary - stimulate water reabsorption in the kidneys - increased blood volume and osmolality
Aldosterone: stimulates reabsorption of salt by the kidneys when dietary intake of salt is low
-retention of salt will promote water reabsorption and increase blood volume
Renin-Angiontensin-Aldosterone System: renin, triggered by low blood pressure and blood volume, causes increased production of angiotensin II; increased blood volume by stimulating the release of aldosterone from adrenal cortex and stimulating thirst centres in the hypothalamus
Atrial Natriutetic Peptide (ANP): hormone that causes increased secretion of Na+ and thus water excretion in the urine, decreasing blood volume

51
Q

Describe how blood volume influences blood pressure.

A

-BP is directly proportional to CO and peripheral resistance
-as blood volume increases; increase in CO
-because of increase in
stroke volume from high
venous return
-increase in CO and thus increases BP

BIOM 3200 (9 decks)

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