Week 6 Lecture ppt Flashcards
1
Q
The heart is composed of what:
A
The heart is composed of two conjoined pumps moving blood through two separate circulatory systems in sequence
2
Q
What do the two conjoined pumps of the heart do?
A
- one pump supplies blood to the lungs,
- the second pump delivers blood to the rest of the body.
3
Q
What do structures of the right side or right heart do?
A
Structures on the right side, or right heart, pump blood through the lungs.
4
Q
What are the two major divisions of the heart?
A
- Pulmonary circulation
- Systemic circulation
5
Q
System that pumps blood through lungs
A
This system is termed the pulmonary circulation
6
Q
What do structures of the left side or left heart do?
A
The left side, or left heart, sends blood throughout the systemic circulation
7
Q
System that pumps blood throughout all the body except the lungs
A
systemic circulation
8
Q
Arteries
A
carry blood from the heart to all parts of the body,
9
Q
What do arteries branch into
A
they branch into arterioles and even smaller vessels, ultimately becoming a fine meshwork of capillaries.
10
Q
What allows the closest contact and exchange between the blood and the interstitial space?
A
Capillaries
11
Q
What is the order of what things blood flows through?
A
Arteries carry blood from heart to all parts of body
Arteries branch into arterioles and even smaller vessels, ultimately becoming capillaries
Venules and then veins carry blood from capillaries back to the heart.
So….
Arteries–> arterioles–>capillaries–> venules–> veins
12
Q
What is the distribution of blood in the circulatory system?
A
9% is in the pulmonary circulation,
7% is in the heart, and
84% is in the systemic circulation.
13
Q
What are the three layers of the heart wall?
A
- epicardium
- myocardium
- endocardium
14
Q
What are the three layers of the heart wall enclosed in?
A
Are enclosed in a double walled membranous sac- the Pericardium
15
Q
The pericardium sac has three main functions:
A
- it prevents displacement of the heart during gravitational acceleration or deceleration,
- it serves as a physical barrier to protect the heart against infection and inflammation coming from the lungs and pleural space, and
- it contains pain receptors and mechanoreceptors that can cause reflex changes in blood pressure and heart rate.
16
Q
Epicardium
A
The smoothness of outer layer of the heart
Minimizes friction between the heart wall and the pericardial sac
17
Q
What is the thickest layer of the heart wall
A
the myocardium
18
Q
The myocardium is composed of
A
The myocardium, is composed of cardiac muscle and is anchored to the heart’s fibrous skeleton.
19
Q
Cardiomyocytes,
A
The heart muscle cells
20
Q
What do the cardiomyocytes do?
A
The heart muscle cells, cardiomyocytes, provide the contractile force needed for blood to flow through the heart and into the pulmonary and systemic circulations.
21
Q
Endocardium
A
The internal lining of the myocardium,
22
Q
What is the endocardium composed of:
A
The endocardium, is composed of connective tissue and squamous cells
23
Q
How does the right heart receive venous blood?
A
The right heart receives venous blood from the systemic circulation through the superior and inferior venae cavae, which join and then enter the right atrium.
24
Q
What happens after the blood enters the right atrium?
A
Blood goes from RA to Right Ventricle.
Blood leaving the right ventricle enters the pulmonary circulation through the pulmonary artery, which divides into right and left branches to transport deoxygenated blood from the right heart to the lungs.
25
What does the pulmonic artery divide into? What does the pulmonic artery do?
Divides into right and left branches to transport deoxygenated blood from the right heart to the lungs.
26
What do the pulmonary arteries branch out into (after left and right branching)
The pulmonary arteries branch further into the pulmonary capillary beds
27
Where does carbon dioxide and oxygen exchange occur?
Pulmonary capillary beds
28
Pulmonary veins
Four pulmonary veins, two from the right lung and two from the left lung, carry oxygenated blood from the lungs to the left side of the heart
29
How does oxygenated blood move through the heart?
Pulmonary veins--> left side of heart--> left atrium--> left ventricle--> aorta--> systemic arteries that supply the body
30
What are the four chambers of the heart?
The heart has four chambers:
the left atrium
the right atrium
the right ventricle
the left ventricle.
31
What kind of pressure system is the right heart?
the right heart is a low-pressure system pumping blood through the lungs
32
What kind of pressure system is the left heart?
the left heart is a high-pressure system pumping blood to the rest of the body
33
The wall thickness of the heart is dependent on what?
The wall thickness of each cardiac chamber depends on the amount of pressure or resistance it must overcome to eject blood.
34
Atrioventricular (AV) valves where are they located?
They fall between the atria and ventricles.
35
What make up the four AV valves
1. Tricuspid valve
2. Mitral valve
3. Aortic semilunar valve
4. Pulmonary semilunar valve
36
How does blood leave the right ventricle?
Through the pulmonary semilunar valve
37
How does blood leave the left ventricle?
Through the aortic semilunar valve
38
What features of the heart ensures that blood flows only one way through the heart?
1. Four heart valves,
2. Four chambers &
3. Pressure gradients they maintain
39
40
The pumping action of the heart consists of what?
The pumping action of the heart consists of contraction and relaxation of the heart muscle, or myocardium.
41
What counts as one cardiac cycle?
Each ventricular contraction and the relaxation that follows it constitute one cardiac cycle.
42
Diastole- what happens
During the period of relaxation, termed diastole, blood fills the ventricles.
43
Systole- what happens
The ventricular contraction that follows the blood filling the ventricles, termed systole, propels the blood out of the ventricles and into the pulmonary and systemic circulations.
44
How many phases of the cardiac cycle are there?
Five phases of the cardiac cycle
45
Blood Flow during the Cardiac Cycle
????????
46
Five phases of the cardiac cycles begin with what
The five phases of the cardiac cycle are said to begin with the opening of the mitral and tricuspid valves and atrial contraction
47
What marks the end of one cardiac cycle?`
Closing of the mitral and tricuspid valves as passive ventricular filling begins marks the end of one cardiac cycle.
48
What are the major coronary arteries?
1. Right Coronary Artery (RCA)
2. Left Coronary Artery (LCA)
49
What do the RCA and LCA travel across?
What do they branch out to become?
traverse the epicardium, myocardium, and endocardium and branch to become arterioles and then capillaries.
50
The left coronary artery divides into:
1. left anterior descending artery (LAD)
2. circumflex artery
51
Left anterior descending artery (LAD)
supplies blood to portions of the left and right ventricles and much of the interventricular septum)
52
Circumflex artery
supplies blood to the left atrium and the lateral wall of the left ventricle
53
What does the cardiac cycle require?
The cardiac cycle requires the transmission of the electrical impulses, called cardiac action potentials from the mycocardium.
54
Conduction system
a collection of specialized cells that enable the myocardium to generate and transmit action potentials without input from the nervous system
55
What are cells that initiate signals called
Pacemakers
56
Where are the pacemaker cells concentrated?
Two sites in the myocardium called nodes
1. Sinoatrial node
2. Atrioventricular node
57
What is the heart innervated by?
1. The autonomic nervous system (both sympathetic and parasympathetic fibers)
58
Conduction system steps: (SA--> AV)
1. Electrical impulses arise in SA node
2. In resting, SA node generates 60-100 action potentials per minute
3. Each action potential travels rapidly from cell to cell and through the atrial myocardium, carrying the action potential onward to the AV node and causing both atria to contract--> systole begins
59
Where do electrical impulses arise?
SA node
60
Where is the SA node located?
The SA node is located at the junction of the right atrium and superior vena cava, just superior to the tricuspid valve.
61
In resting, how many action potentials does the SA node generate per minute?
60-100 per minute
62
Where is the AV node located?
The AV node, located in the right atrial wall superior to the tricuspid valve and anterior to the ostium of the coronary sinus
63
What does the AV node do?
it conducts the action potentials onward to the ventricles
64
Depolarization
Electrical activation of the muscle cells
65
What is depolarization caused by?
Depolarization, is caused by the movement of ions, including sodium, potassium, calcium, and chloride, across cardiac cell membranes.
66
Repolarization
Deactivation of muscle cells
67
Membrane potential
Movement of ions into and out of the cell creates an electrical (voltage) difference across the cell membrane, called the membrane potential.
68
What happens to the inside of the cell during depolarization?
The inside of the cell becomes less negatively charged as positive ions move inside
69
What are the parts of a ECG?
P wave
PR interval
QRS complex
ST interval
QT interval
T wave
70
P wave of ECG
represents atrial depolarization
71
PR interval
is a measure of time from the onset of atrial activation to the onset of ventricular activation
72
PR interval represents what?
The PR interval represents the time necessary for electrical activity to travel from the sinus node through the atrium, AV node, and His-Purkinje system to activate ventricular myocardial cells.
73
The QRS complex represents what?
The QRS complex represents the sum of all ventricular muscle cell depolarization.
74
What occurs during the ST interval?
During the ST interval, the entire ventricular myocardium is depolarized.
75
T wave
represents ventricular repolarization
76
Automaticity
The property of generating spontaneous depolarization to threshold, enables the SA and AV nodes to generate cardiac action potentials without any external stimulus.
77
Rhythmicity
Rhythmicity is the regular generation of an action potential by the heart's conduction system.
78
What sets the rate for Rhythmicity?
SA node
79
Cardiac innervation: What does the ANS influence
1. rate of impulse generation (firing)
2. depolarization of the myocardium
3. repolarization of the myocardium
4. strength of the atrial and ventricular contraction
80
What does sympathetic stimulation of nerve fibers do?
sympathetic stimulation increases electrical conductivity and the strength of myocardial contraction
81
What does parasympathetic stimulation of nerve fibers do?
vagal parasympathetic nerve activity does the opposite of sympathetic, slowing the conduction of action potentials through the heart and reducing the strength of contraction.
82
What do the sympathetic and parasympathetic nerves do in the cardiac cycle?
The sympathetic and parasympathetic nerves affect the speed of the cardiac cycle (heart rate, or beats per minute)
83
How does the parasympathetic nervous system affect the heart specifically?
The parasympathetic nervous system affects the heart through the vagus nerve, which releases acetylcholine.
Acetylcholine causes a decreased heart rate and slows conduction through the AV node.
84
Acetylcholine
Acetylcholine causes a decreased heart rate and slows conduction through the AV node.
85
Myocardial contractibility
Myocardial contractility is a change in developed tension at a given resting fiber length, which basically is the ability of the heart muscle to shorten.
Myocardial contractility is defined as the force with which the ventricles contract.
86
Cardiac output- how is it calculated?
Cardiac output is calculated by multiplying the heart rate in beats per minute (beats/min) by the stroke volume (volume of blood ejected during systole) in liters per beat.
CO = HR x SV
87
Stroke Volume
Volume of blood ejected during systole in liters per beat. (L/beat)
88
Ejection fraction
With each heartbeat, the ventricles eject much of their blood volume, the amount ejected per beat is called the ejection fraction
89
What increases ejection fraction?
The ejection fraction is increased by factors that increase contractility, such as increased sympathetic nervous system activity.
90
How is the ejection fraction calculated?
The ejection fraction is calculated by dividing the stroke volume by the end-diastolic volume.
91
What factors increase ejection fraction?
The ejection fraction is increased by factors that increase contractility, such as increased sympathetic nervous system activity.
92
The factors that determine cardiac output?
1. Preload
2. Afterload
3. Myocardial contractibility
4. Heart rate
93
What are the three factors that effect Stroke Volume?
1. Preload
2. Afterload
3. Contractility
94
Preload
Preload is the volume and pressure inside the ventricle at the end of diastole (ventricular end-diastolic volume [VEDV] and pressure [VEDP])
95
Preload is determined by what?
Preload is determined by two primary factors:
(1) the amount of blood left in the ventricle after diastole (end-dystolic volume) and
(2) the amount of venous blood returning to the ventricle during diastole.
96
During preload, What is end systolic volume dependent on?
End-systolic volume is dependent on the strength of ventricular contraction and the resistance to ventricular emptying.
97
During preload, Venous return is dependent on
Venous return is dependent on blood volume and flow through the venous system and the atrioventricular valves
98
Starling Law
Starling law of the heart indicates that the volume of blood in the heart at the end of diastole, as the volume determines the length of its muscle fibers, is directly related to the force of contraction during the next systole.
99
Ventricular afterload
Ventricular afterload is the resistance to ejection of blood from the ventricle.
It is the load the muscle must move during contraction.
Afterload is formally defined as the load against which a muscle exerts its force (i.e., the load a muscle must overcome to contract).
100
What is an index of afterload?
The aortic systolic pressure is an index of afterload.
101
Before blood can be pumped out during systole, what must occur?
Pressure in the ventricle must exceed the aortic pressure before blood can be pumped out during systole.
102
What does low aortic pressures (decreased afterload) enable the heart to do?
Low aortic pressures (decreased afterload) enable the heart to contract more rapidly and efficiently
103
What does high aortic pressures (increased afterload) enable the heart to do?
high aortic pressures (increased afterload) slow contraction and cause higher workloads against which the heart must function to eject blood.
104
Increased aortic pressure is the result of what?
Increased aortic pressure is usually the result of increased systemic vascular resistance (SVR),
105
What is systemic vascular resistance (SVR) also known as?
Total Peripheral Resistance (TPR)
106
How to calculate SVR?
SVR is calculated by dividing the mean arterial pressure by the cardiac output
107
Myocardial Contractility
Force of contraction
or
Degree of myocardial fiber shortening
108
Three major factors determine the force of contraction:
1. Changes in the stretching of the ventricular myocardium caused by changes in VEDV (preload).
2. Alterations in the inotropic stimuli of the ventricles
3. Adequacy of myocardial oxygen supply.
109
Inotropic agents
Hormones, neurotransmitters, or medications that affect contractility are called inotropic agents.
110
What are the most important inotropic agents?
The most important endogenous positive inotropic agents are epinephrine and norepinephrine released from the sympathetic nervous system.
111
What is the most important negative inotropic agent?
The most important negative inotropic agent is acetylcholine released from the vagus nerve.
112
How does severe hypoxemia effect contractility?
With severe hypoxemia (arterial O2 saturation less than 50%), contractility is decreased.
113
How does moderate hypoxemia effect contractility?
Moderate degrees of hypoxemia may increase contractility by enhancing the myocardial response to circulating catecholamines.
114
Changes in preload, afterload and contractility can lead to what?
Heart failure
115
What is the primary determinant of heart rate?
SA node
116
The control of heart rate includes activity of:
1. The central nervous system,
2. Autonomic nervous system,
3. Neural reflexes,
4. Atrial receptors, and
5. hormones
117
What is involved in neural reflex?
Baroreceptor reflexes
118
What does output from baroreceptor reflex influence?
Output from the baroreceptor reflexes influences short-term regulation of the vascular smooth muscle of resistance arteries, myocardial contractility, and heart rate, all components of blood pressure control.
119
What does baroreceptors do if bp decreases
If blood pressure decreases, the baroreceptor reflex accelerates the heart rate, increases myocardial contractility, and increases vascular smooth muscle contraction in the arterioles, thus raising blood pressure.
120
What is baroreceptor reflex important for maintaining?
This reflex is critical to maintaining adequate tissue perfusion.
121
What do baroreceptor reflexes do when bp increases?
When the blood pressure increases, the baroreceptors increase their rate of discharge,
These reflexes increase parasympathetic activity and decrease sympathetic activity, causing the resistance arteries to dilate, decreasing myocardial contractility and the heart rate.
122
Bainbridge reflex
The Bainbridge reflex is the name for the changes in the heart rate that may occur after intravenous infusions of blood or other fluid.
123
Peripheral vascular system
Peripheral vascular system is the term used to describe the part of the systemic circulation that supplies the skin and the extremities, particularly the legs and feet.
124
Blood vessels are composed of three layers:
1. The tunica intima (innermost layer)
2. The tunica media (middle layer)
3. The tunica externa or adventitia (outermost layer)
125
Blood flow
Blood flow, the amount of fluid moved per unit of time
126
How is blood flow expressed?
Is usually expressed as liters or milliliters per minute (L/min or ml/min).
127
Factors that influence blood flow include?
Pressure,
Resistance,
Velocity,
Laminar versus turbulent flow, and
Compliance,
128
Of the factors that affect blood flow, what is the most important?
1. Pressure
2. Resistance
129
Factors affecting blood flow: Pressure
Pressure in a liquid system is the force exerted on the liquid per unit area
130
How is pressure expressed in units?
millimeters of mercury (mm Hg),
or torr (1 torr = 1 mm Hg).
131
Factors affecting blood flow: Resistance
Resistance is the opposition to blood flow.
132
What contributes to resistance?
Most opposition to blood flow results from the diameter and length of the vessels.
133
Why does changes in blood flow through an organ occur?
Changes in blood flow through an organ result from changes in the vascular resistance within the organ because of:
1. increases or decreases in vessel diameter and
2. the opening or closing of vascular channels.
134
How is resistance related to blood flow?
Resistance in a vessel is inversely related to blood flow—that is, increased resistance leads to decreased blood flow.
135
What is the most important factor determining resistance in a single vessel?
Clinically, the most important factor determining resistance in a single vessel is the radius or diameter of the vessel's lumen.
136
Viscosity
The consistency of fluid
137
Viscosity: Thick fluid moves more slowly, how does that affect resistance?
Thick fluids move more slowly and cause greater resistance to flow than thin fluids
138
What does the viscosity of blood depends on what?
The viscosity of blood depends on the red cell content.
Greater the percentage of rbc, the more viscous the blood.
139
Blood velocity
Blood velocity, or speed, is the distance blood travels in a unit of time,
140
How is blood velocity expressed?
usually centimeters per second (cm/sec).
141
How is Blood velocity related to blood flow?
It is directly related to blood flow (the amount of blood moved per unit of time)
142
How is Blood velocity related to cross-sectional area of the vessel?
inversely related to the cross-sectional area of the vessel in which the blood is flowing
143
Laminar flow
In laminar flow, concentric layers of molecules move “straight ahead,” with each layer flowing at a slightly different velocity
144
What is turbulent blood flow caused by?
Where flow is obstructed, the vessel turns of branches, or blood flows over rough surfaces, the flow becomes turbulent with whorls or eddy current that produce noise, causing murmur to be heard.
145
Relationship between turbulence and resistance?
Resistance increases with turbulence
146
Vascular Compliance
Vascular compliance is the increase in volume a vessel can accommodate with a given increase in pressure.
147
What is the opposite of compliance?
Stiffness is the opposite of compliance.
148
What is arterial blood pressure determined by:
The arterial blood pressure is determined by the cardiac output multiplied by the peripheral resistance
CO x PR = BP
149
Systolic Blood Pressure
The systolic blood pressure is the highest arterial blood pressure after ventricular contraction or systole.
150
Diastolic Blood Pressure
The diastolic blood pressure is the lowest arterial blood pressure that occurs during ventricular filling or diastole.
151
Mean Arterial Pressure (MAP)
The average pressure in the arteries throughout the cardiac cycle
152
What does the MAP depend on?
depends on:
1. The elastic properties of the arterial walls and
2. The mean volume of blood in the arterial system.
153
Tissue Perfusion
Blood supply to the capillary beds
154
The cardiac output can be changed by:
The cardiac output (minute volume) of the heart can be changed by:
1. Alterations in the heart rate,
2. stroke volume (volume of blood ejected during each ventricular contraction),
3. or both.
155
What is primarily a function of arteriolar diameter?
Total resistance in the systemic circulation (known as SVR or TPR)
156
How does Baroreceptors affect Cardiac output?
When activated (stretched), the baroreceptors decrease cardiac output by lowering the heart rate, stroke volume, and peripheral resistance, and thus lower blood pressure.
157
What are arterial chemoreceptors?
Specialized areas within the aortic arch and carotid arteries are sensitive to concentrations of O2, carbon dioxide (CO2), and hydrogen ions (pH) in the blood
158
Arterial chemoreceptors?
A decrease in arterial oxygen concentration (hypoxemia), an increase in arterial PaCO2 concentration, or to a lesser extent a decrease in arterial blood pH causes a reflexive increase in heart rate, stroke volume, and blood pressure.
159
Effect of hormones on bp? By constricting or dilating the arterioles in organs, hormones can:
By constricting or dilating the arterioles in organs, hormones can
(1) increase or decrease the flow in response to the body's needs,
(2) redistribute blood volume during hemorrhage or shock, and
(3) regulate heat loss.
160
What are the key vasoconstrictor hormones include:
angiotensin II, vasopressin (or antidiuretic hormone), epinephrine, and norepinephrine.
161
The main vasodilator hormones are:
The main vasodilator hormones are the atrial natriuretic hormones.
162
How do aldosterone, vasopressin and natriuretic hormones influence stroke volume and bp?
By causing fluid retention or loss, aldosterone, vasopressin, and the natriuretic hormones can influence stroke volume and thus blood pressure.
163
What are the vasoconstrictor hormones that are part of the renin-angiotensin-aldosterone system:
The vasoconstrictor hormones include epinephrine; norepinephrine; angiotensin II, which is part of the renin-angiotensin-aldosterone system;
164
How do vasopressin and aldosterone affect bp?
Vasopressin and aldosterone, however, affect blood pressure by increasing blood volume through their influence on fluid reabsorption in the kidney and by stimulating thirst.
**Vasopressin causes the reabsorption of water from tubular fluid in the distal tubule and collecting duct of the nephron. Aldosterone, the end product of the renin-angiotensin-aldosterone system, stimulates the reabsorption of sodium, chloride, and water from the same locations in the kidney**
165
Effect of natriuretic peptides (NPs) or hormones
Increased pressure or diastolic volume in the heart stimulates the release of these peptide hormones.
166
Three principal natriuretic peptides:
1. Atrial Natriuretic Peptide (ANP)
2. B-type Natriuretic Peptide (BNP)
3. C-type natriuretic peptide (CNP),
4. and urodilatin,
167
Other mediators that have been demonstrated to cause arteriolar vasodilation or vasocontriction?
Some of the vasodilating mediators include nitric oxide (NO), adrenomedullin (ADM), the endothelins, and prostacyclin.
168
Hypertension
Hypertension is consistent elevation of systemic arterial blood pressure.
169
How has hypertension been defined in numbers:
It has recently been redefined as a sustained systolic blood pressure (SBP) of 130 mm Hg or a diastolic blood pressure (DBP) of 80 mm 593Hg or greater
170
Most cases of hypertension are diagnosed as what?
Primary hypertension
171
What is primary hypertension also called?
(also called essential or idiopathic hypertension)
172
Secondary Hypertension:
Secondary hypertension is caused by an underlying disorder such as renal disease.
Secondary hypertension is caused by an underlying disease process or medication that raises PVR or cardiac output.
173
Cause of Primary hypotension:
A combination of genetic and environmental factors
174
Risk factors for Primary Hypertension:
Family History
Diet
Tobacco and Alcohol Consumption
Obesity and glucose intolerance
175
Complicated Hypertension
As hypertension becomes more severe and chronic, tissue damage can occur in the blood vessels and tissues leading to target organ damage in the heart, kidney, brain, and eyes.
176
Myocardial Hypertrophy
Hypertrophy is characterized by a myocardium that is thickened, scarred, and less able to relax during diastole, leading to heart failure with preserved ejection fraction.
177
Hypertensive crisis
Hypertensive crisis is rapidly progressive hypertension in which systolic pressure is ≥180 mmHg and or diastolic pressure is ≥120 mmHg.
178
Angiotensin family:
which consists of angiotensin I, angiotensin II, and angiotensin III.
179
Angiotensin I
Angiotensin I is the precursor of angiotensin II
180
Actions of Angiotensin II and What do the actions cause?
The most prominent actions of angiotensin II are :
1. vasoconstriction and
2. stimulation of aldosterone release.
Both actions raise bp
181
How does Angiotensin II cause vasoconstriction directly?
1. The compound acts directly on vascular smooth muscle (VSM) to cause contraction.
182
How does Angiotensin II cause vasoconstriction indirectly?
angiotensin II can cause vasoconstriction indirectly by acting on:
(1) sympathetic neurons to promote norepinephrine release,
(2) the adrenal medulla to promote epinephrine release, and
(3) the central nervous system to increase sympathetic outflow to blood vessels.
183
Where is aldosterone made?
Angiotensin II acts on the adrenal cortex which produces Aldosterone.
184
How are aldosterone secretions enhanced?
Aldosterone secretion is enhanced when sodium levels are low and when potassium levels are high.
185
How does aldosterone effect blood volume and blood pressure?
After being released from the adrenal cortex, aldosterone acts on distal tubules of the kidney to cause retention of sodium and excretion of potassium and hydrogen.
-Because retention of sodium also causes water to be retained, aldosterone increases blood volume, which causes blood pressure to rise.
186
Renin
Renin catalyzes the formation of angiotensin I from angiotensinogen.
187
Release of renin can be triggered by multiple. factors
Release increases in response to a decline in blood pressure, blood volume, plasma sodium content, or renal perfusion pressure.
188
What inhibits the release of renin secretion?
Renin secretion is inhibited by elevation of blood pressure, blood volume, and plasma sodium content.
189
Angiotensin-Converting Enzyme (Kinase II):
ACE catalyzes the conversion of angiotensin I (inactive) into angiotensin II (highly active).
190
How fast does conversion of angiotensin I --> angiotensin II occur? Why?
Because ACE is abundant, conversion of angiotensin I into angiotensin II occurs almost instantaneously after angiotensin I has been formed.
191
The RAAS, acting through angiotensin II, raises blood pressure through two basic processes:
The RAAS, acting through angiotensin II, raises blood pressure through two basic processes: vasoconstriction and renal retention of water and sodium.
192
?????
Vasoconstriction raises blood pressure by increasing total peripheral resistance; retention of water and sodium raises blood pressure by increasing blood volume.
193
ACE inhibitors are important for what?
The ACE inhibitors are important drugs for treating hypertension, heart failure, diabetic nephropathy, and MI.
194
Adverse Effects of ACE inhibitors
Their most prominent adverse effects are cough, angioedema, first-dose hypotension, and hyperkalemia.
195
ACE inhibitors produce their beneficial effects and adverse effects by:
(1) reducing levels of angiotensin II (through inhibition of ACE) and
(2) increasing levels of bradykinin (through inhibition of kinase II)
196
Through reducing reducing levels of Angiotensin II, what do ACE inhibitors do?
By reducing levels of angiotensin II, ACE inhibitors can dilate blood vessels (primarily arterioles and, to a lesser extent, veins); reduce blood volume (through effects on the kidney); and, importantly, prevent or reverse pathologic changes in the heart and blood vessels mediated by angiotensin II and aldosterone.
197
What suffix does all ACE inhibitors end in?
"prils"
198
If a patient reports angiodema, what should the patient never take again?
ACE inhibitors
199
Drug interactions caused by ACE inhibitors:
1. Diuretics
2. Antihypertensive Agents
3. Drugs that raise potassium levels
4. Lithium
5. NSAIDs
200
