Chapter 11 Cardiovascular System Part 1 (Slide #1-62) Flashcards
(130 cards)
1
Q
From superficial to deep, name the layers of the heart wall.
A
- Epicardium(visceral pericardium)
- Myocardium
- Endocardium
2
Q
Why is it important that cardiac tissue be richly supplied with mitochondria and capillaries
A
Cardiac tissue is metabolically active and dependent on mitochondrial activity for ATP obtaining oxygen and nutrients from local capillaries
3
Q
Describe the heart’s location
A
Located within the pericardial sac in the anterior mediastinum, deep to the sternum and superior to the diaphragm
4
Q
Name and describe the shallow depressions and grooves found on the heart’s external surface.
A
Anterior interventricular sulcus marks the boundary b/t the left and right ventricles on the heart’s anterior surface;
the shallower posterior interventricular sulcus marks the boundary b/t the left and right ventricles on the posterior surface; and the coronary sulcus is a deep groove that marks the border b/t the atria and the ventricles
5
Q
Describe what happens to blood flow in the aorta during elastic rebound.
A
Some blood in aorta is driven forward into the systemic circuit, and some is forced back toward the left ventricle and into the coronary arteries
6
Q
Identify the main vessel that drains blood from the myocardial capillaries.
A
Cardiac vein
7
Q
Damage to the semilunar valve on the right side of the heart would affect blood flow to which vessel
A
-would affect blood flow to the pulmonary artery
8
Q
What prevents the AV valves from swinging into the atria?
A
It pulls on the chordae tendinae
9
Q
Why is the left ventricle more muscular than the right ventricle
A
Because the left ventricle has to be able to pump blood through the whole body and the right ventricle only has to send it to the lungs
10
Q
Provide the alternate terms for the contraction and relaxation of heart chambers.
A
for contraction= systole
for relaxation= diastole
11
Q
Describe the phases of the cardiac cycle.
A
- atrial systole
- atrial diastole
- ventricular systole
- ventricular diastole
12
Q
Is the heart always pumping blood when pressure in the left ventricle is rising? Explain
A
No.
- when pressure in the L ventricle 1st rises, the heart is contracting BUT no blood is leaving the heart
- during the initial phase of contraction, BOTH the AV valves and semilunar valves are CLOSED
- the increase in pressure is the result of increased tension as the cardiac muscle contracts
- when the pressure in the ventricle EXCEEDS the pressure in the aorta, the aortic semilunar valves are FORCED OPEN, and blood is rapidly EJECTED from the ventricle
13
Q
Describe the sites and actions of the cardioinhibitory and cardioacceleratory center
A
The cardioacceleratory center in the medulla oblongata activates sympathetic neurons to increase heart rate;
the cardioinhibitory center (also in the medulla oblongata) controls the parasympathetic neurons that slow heart rate
14
Q
Compare bradycardia with tachycardia.
A
- Bradycardia is a heart rate below 60 beats per minute;
- tachycardia is a heart rate above 100 beats per minute
15
Q
List five important features of the ECG, and indicate what each represents
A
1.the P wave (atrial depolarization),
2 .the QRS complex (ventricular depolarization)
3.T wave (ventricular repolarization
4.
5.
16
Q
Define Cardiac output
A
-the blood volume (in liters) ejected per minute by the left ventricle
17
Q
Why is it a potential problem if the heart beats too rapidly?
A
the heart pumps in proportion to the amount of blood that enters. a heart that beats too rapidly does not have sufficient time to fill completely between beats. thus, when the heart beats too fast, very little blood leaves the ventricles and enters the circulation so tissues suffer damage from inadequate blood supply.
18
Q
Define blood flow, and describe its relationship to blood pressure and peripheral resistance
A
BLOOD FLOW is
19
Q
What is the relationship between blood pressure and blood flow?
A
increased blood pressure = increased blood flow
20
Q
What is the relationship between resistance and blood flow?
A
increased resistance = decreased blood flow
21
Q
Which vessels endure the highest blood pressure?
A
Aorta and large arteries
22
Q
In a healthy individual, is blood pressure higher in the aorta or in the inferior vena cava? Explain.
A
Blood pressure is greater at the aorta than at the inferior vena cava. If the pressure were higher in the aorta, blood would flow in the reverse direction.
23
Q
Describe autoregulation as it pertains to cardiovascular function.
A
Involves local factors changing the pattern of blood flow within capillary beds in response to chemical changes in interstitial fluids
24
Q
Explain the function of baroreceptor reflexes
A
- Rapid,
- SHORT TERM,
- reflex adjustments to MAP (blood pressure).
- Controls MAP by regulating CO and TPR.
Recheck!
25
Describe the changes in cardiac output and blood flow during exercise.
1. vasodilatation occurs, peripheral resistance drops, and blood flow through the capillaries increases
2. venous return increases as skeletal muscle contractions squeeze blood along the peripheral veins at the same time, each inhalation, creates negative pressures in the thoracic cavity that pulls blood into the vena cava from their branches. This mechanism is called the respiratory pump
3. Cardiac output rises, primarily due to the increased venous return
26
Why does blood flow to visceral organs decrease during exercise?
Major changes in the peripheral distribution of blood allow a massive increase in blood flow to skeletal muscles while preventing a potentially disastrous decline in systemic stimulation
27
List the five general classes of blood vessels
```
1-arteries
2-arterioles
3-capillaries
4-venules
5-veins
```
28
Describe a capillary.
Numerous tiny vessels that allow for the exchange of substances between the blood and body tissues
29
What is the role of precapillary sphincters
a muscle fiber that regulates blood flow into the capillary bed
30
Describe blood flow through an arteriovenous anastomosis
Vessels through which blood is shunted from arterioles to venules without passing through the capillaries
-Google
31
Define varicose veins.
a structural defect due to incompetent valves, is a common vascular problem, especially in the obese and people who stand for long hours. It is a predisposing factor for thrombophlebitis.
32
Why are valves located in veins, but not in arteries?
veins need valves to create pressure to pump the blood to the heart. valves assist in returning venus blood to the heart.
33
How is blood flow maintained in veins to counter the pull of gravity?
* Contraction of the surrounding skeletal muscles squeezes venous blood toward the heart.
* This mechanism, the muscular pump, is assisted by the presence of valves in the veins, which prevent back flow of the blood. The respiratory pump, which results from the increase in internal pressure of the thoracic cavity during exhalation pushes blood into the right atrium.
Recheck!
34
Identify the two circulatory circuits of the cardiovascular system
1. Pulmonary system (system that goes to the lungs)
| 2. Systemic system (system that goes to the rest of the body
35
Trace the path of a drop of blood through the lungs, beginning at the right ventricle and ending at the left atrium.
right ventricle --> right and left pulmonary arteries --> pulmonary arterioles --> alveolar capillaries --> pulmonary venues --> pulmonary veins --> left atrium
36
Name the two large veins that collect blood from the systemic circuit
aorta
37
Identify the largest artery in the body.
aorta
38
Trace Besides containing valves, cite another major difference between the arterial and venous systems
existence of dual venous drainage in the neck and limbs
39
Name the two arteries formed by the division of the brachiocephalic trunk.
right common carotid artery and the right subclavian artery
40
Name the two arteries formed by the division of the brachiocephalic trunk.
right common carotid artery and the right subclavian artery
41
A blockage of which branch from the aortic arch would interfere with blood flow to the left arm?
A blockage of the left subclavian artery would interfere with blood flow to the left arm.
42
Identify the branches of the celiac trunk
3 Immediate Branches
left gastric artery
splenic artery,
common hepatic artery
43
The distal end of this artery contains receptors (baroreceptors) for blood pressure regulation.
Carotid
44
Name the arterial structure in the neck region that contains baroreceptors.
Carotid
Recheck!
45
Identify the veins that combine to form the
| brachiocephalic vein.
external jugular
internal jugular
vertebral
subclavian veins
46
Which vessel collects most of the venous blood inferior to the diaphragm
Inferior vena cavae
47
List the unpaired branches of the abdominal aorta that supply blood to the visceral organs
celiac trunk, superior mesenteric artery, inferior mesenteric artery
Recheck!
48
Identify the three veins that merge to form the hepatic portal vein.
gastric
inferior mesenteric
superior mesenteric
49
what is the location of the heart in the thorax
the heart is in the mediastinum between the lungs
50
which heart chamber has the thickest walls? What is the functional significance of this structural difference?
the left ventricle has the thickest walls. This reflects its function, which is to pump blood through the whole body.
51
how does the function of the systemic circulation differ from that of the pulmonary circulation?
Pulmonary circulation strictly serves gas exchange. Oxygen is loaded and CO2 is unloaded from the blood in the lungs. Systemic circiulation provides oxygen laden blood to all body organs.
52
why are the heart valves important
keep blood flowing forward through the heart
53
Why might a thrombus in a coronary artery cause sudden death?
The coronary artery supply the myocardium( cardiac muscle) with oxygen. If that circulation fails, the heart fails.
54
Are the ventricular Cardiac Cells contracting isometrically or isotonically during the first part of
phase 2?
The cells contract Isometrically until they have enough force to overcome the back pressure of the blood against the seminular valves, at which point their contraction become isotonic
55
What is the function of the intrinsic conduction system of the heart?
- coordinates the actions of the heart chambers and causes the heart to beat faster than it would other wise
56
To which heart chambers do the terms systole and diastole usually apply?
Left Ventricle
57
What causes the lub-dub sounds heard with a stethoscope?
The operation of the heart valves
58
What does the term cardiac output mean?
Amt of blood pumped out by each side of the heart by 1 minute.
59
What would you expect to happen to the heart of an individual with a fever? Why?
Fever increases the heart rate bec. the rate of metabolism of the cardiac muscle increases.
60
What is the most important factor affecting stroke volume?
Venous return
61
Assume u are viewing a blood vessel under the microscope. It Has a large lopsided lumen, relatively thick tunica externa, and arelatively thin tunica media. Which kind of blood vessel is this?
It is a vein.
62
Assume u are viewing a blood vessel under the microscope. It Has a large lopsided lumen, relatively thick tunica externa, and arelatively thin tunica media. Which kind of blood vessel is this?
It is a vein.
Till #12 only.
63
The Cardiovascular System
*A closed system of the heart and blood vessels
- The heart pumps blood
- Blood vessels allow blood to circulate to the body
*Functions to deliver oxygen, nutrients and hormones while removing carbon dioxide and other waste products
64
What is the location of the heart?
Thorax between the lungs in the inferior mediastinum
65
What is the Orientation of the heart?
Pointed apex lies in the 5th / 6th ICS
Base points toward right shoulder
66
What is the Size of the heart?
About the size of your fist
Weighs less than a pound
67
The Heart Coverings
Pericardial sac
Pericardial cavity
68
Pericardial sac
Surrounds heart
Formed by parietal pericardium
69
Pericardial cavity
*Bounded by two serous membranes
- Visceral pericardium (epicardium) attached to heart
- Parietal pericardium forming outer wall of cavity
*Contains 15–50 mL pericardial (serous) fluid (secreted by visceral pericardium
70
Cardiac Muscle Tissue
* Smaller cell size than skeletal muscle tissue
* Branching interconnections between cells
* Specialized intercellular connections
-Intercalated discs:
= Gap junctions
= Desmosomes
71
Cardiac Muscle Cells
* Found only in heart - cardiomyocytes
* Dependent on aerobic metabolism
- High quantity of mitochondria
- High myoglobin reserves
- Extensive capillary supply
72
Three Layers of the Heart
1. Epicardium (visceral pericardium)
2. Myocardium
3. Endocardium
73
1.Epicardium (visceral pericardium)
- Serous membrane covering outer surface of heart
| - Attached to myocardium
74
2.Myocardium
- Muscular wall of heart composed of concentric layers of cardiac muscle tissue
- Also contains blood vessels and nerves
75
3.Endocardium
Endocardium
Simple squamous epithelium with underlying areolar tissue
Lines inner surfaces of heart including
76
3.Endocardium
Simple squamous epithelium with underlying areolar tissue
Lines inner surfaces of heart including
77
Four chambers of the heart
Atria:
1. Right atrium
2. Left atrium
Ventricles:
3. Right ventricle – pumps deoxygenated blood into pulmonary circulation – low pressure
4. Left ventricle - pumps oxygenated blood to systemic system – high pressure
78
The Heart: Septa
Interventricular septum
Interatrial septum
79
Interventricular septum
separates the ventricles
80
Interatrial septum
- separates the atria
81
The Heart: Valves
* Lie at both entrances and exits of the ventricles
* Four valves – 2 AV valves and 2 semilunar valves
* Flaps/cusps held in place by chordae tendineae (“heart strings")
82
1. Atrioventricular valves (AV)
* Found between atria and ventricles
| * allows flow into ventricles - closure of these valves make the 1st heart sound (lub)
83
Atrioventricular valves (AV) (Contd)
Bicuspid or Mitral valve (left)
Tricuspid valve (right
84
2. Semilunar valves
* controls flow of blood out of R and L ventricles
- closure of these valves cause the 2nd heart sound (dub)
- Pulmonary valve (right)
- Aortic valve (left)
85
a) Operation of the AV valves
1. Blood returning to the
atria puts pressure against
AV valves; the AV valves
are forced open.
2. As the ventricles fill,
AV valve flaps hang
limply into ventricles.
3. Atria contract,
forcing additional
blood into ventricles
AV valves open;
atrial pressure
greater than
ventricular pressure
4. Ventricles contract,
forcing blood against
AV valve flaps
5. AV valves close
6. Chordae tendineae
tighten, preventing
valve flaps from
everting into atria
AV valves closed;
atrial pressure
less than
ventricular pressure
86
b. Operation of the semilunar valves
```
1.As ventricles contract
and intraventricular
pressure rises, blood
is pushed up against
semilunar valves,
forcing them open.
```
Semilunar valves open
```
2. As ventricles relax
and intraventricular
pressure falls, blood
flows back from
arteries, filling the
leaflets of semilunar
valves and forcing
them to close.
```
Semilunar valves closed
87
Heart Sounds
*Produced by heart valves closing, blood rushing through heart, or heart muscle contracting
* First sound "lubb" (S1) longer than second
- Marks start of ventricular contraction
- Produced as AV valves close
* Second sound "dupp" (S2)
- Occurs when semilunar valves close
* Third and fourth sounds from blood flowing into ventricles (S3) and atrial contraction (S4)
- Usually very faint and not heard in healthy adult
88
Coronary Circulation
The heart has its own blood supply
89
Coronary arteries
- branch from the aorta
90
Cardiac veins
drain the myocardium
91
Coronary sinus
large vein on the posterior of the heart, receives blood from cardiac veins drains into the right atrium
92
The Heart: Associated Great Vessels
Aorta
Pulmonary arteries (2)
Vena cava (2)
Pulmonary veins (4)
93
Aorta
– oxygenated blood
Carries blood from left ventricle out to the body
94
Pulmonary arteries (2)
- deoxygenated blood
Carries blood from right ventricle to the lungs
95
Vena cava (2) –
--deoxygenated blood
Carries blood from body to right atrium
96
Pulmonary veins (4) –
--oxygenated blood
Carries blood from lungs to left atrium
97
Blood Flow Through the Heart
ORDER:
- from Venae cava (superior and inferior)
- right atrium
- through the tricuspid valve
- right ventricle
- through the pulmonary semilunar valve
- pulmonary arteries (right and left)
- Lungs (for oxygenation)
98
Blood Flow Through the Heart
| slide # 29
ORDER:
- from Pulmonary veins (2 right and 2 left)
- left atrium
- through the bicuspid valve
- left ventricle
- aortic semilunar valve
- aorta
- systemic circulation
99
Intrinsic Conduction System of the Heart
- Cardiac muscle is able to initiate its own contraction in a regular way, but its rate is influenced by both intrinsic and extrinsic factors
- The intrinsic conduction (nodal) system increases the rate of heart contraction and ensures that the heart beats as a unit
100
Intrinsic Conduction System of the Heart
Sinoatrial (SA) node is the heart’s pacemaker
Atrioventricular (AV) node is at the junction of the atria and ventricles
Atrioventricular (AV) bundle (bundle of His) is in the interventricular septum
Bundle branches are in the interventricular septum
Purkinje fibers spread within the ventricle wall muscles
101
Sinoatrial (SA) node
is the heart’s pacemaker
102
Atrioventricular (AV) node
is at the junction of the atria and ventricles
103
Atrioventricular (AV) bundle (bundle of His)
is in the interventricular septum
104
Bundle branches
are in the interventricular septum
105
Purkinje fibers
spread within the ventricle wall muscles
106
Cardiac Innervation
* Autonomic nervous system adjusts HR and force of contraction
* Cardiac centers in medulla oblongata
- PNS effects: decreases heart rate
- SNS effects: increases heart rate and force of contraction
107
Heart Rates
Resting heart rate:
- Varies with age, health, physical conditioning
- Normal range 60–100 bpm
108
Factors Affecting Heart Rate
See Slide # 37 for the Table
109
Electrocardiogram (ECG or EKG) is
- Recording of electrical activity of heart using electrodes on surface of body
- slide 38
110
Electrocardiogram
- P wave shows depolarization of atria
- QRS complex shows depolarization of ventricles
- T wave shows ventricular repolarization
111
Tachycardia –
heart rate over 100 beats per minute
112
Bradycardia –
heart rate less than 60 beats per minute
113
Cardiac cycle
the sequence of events that occurs during a heartbeat - a coordinated contraction and relaxation of chambers of heart
1. Cardiac cycle begins with all chambers relaxed
- Ventricles partially filled with blood
2. Atrial systole
- Atria contract, filling ventricles
3. Atrial diastole continues until start of next cardiac cycle
4. Ventricular systole – first phase
- AV valves pushed closed by ventricular contraction
- Semilunar valves still closed
- Isovolumetric contraction (no change in volume)
5. Ventricular systole – second phase
-Increasing pressure pushes open
semilunar valves and blood flows out of ventricle
- Ventricular ejection
6. Ventricular diastole – early
- Pressure drops in ventricles
- Blood flowing back against semilunar valve cusps closes valves
7. Isovolumetric relaxation
- Semilunar valves closed; AV valves still closed
- Blood flowing into atria
8. Ventricular diastole – late
- All chambers relaxed
- AV valves open and ventricles passively fill to 70 percent final volume
* Ventricular diastole lasts through end of one cardiac cycle and into beginning of next (until next ventricular systole)
114
Two basic phases of cardiac cycle
1. Contraction (systole)
- Blood pushed into adjacent chamber or arterial trunk
2. Relaxation (diastole)
- Chamber fills with blood
115
The Cardiac Cycle
Slide 43 and 47 for the table
116
Cardiac Cycle ensure that
- there is adequate blood flow to all body parts
* Average HR is 70 - 75 beats per minute
* Cardiac cycle takes about 0.8 seconds to complete
117
If HR is faster than cardiac cycle time:
*Diastole shortens – chambers don’t fill completely with blood, so less is pumped out per beat
118
The Heart: Cardiac Output
Cardiac output (CO or Q)
Stroke volume (SV)
Heart rate (HR)
119
Regulation of Heart Rate
1. Increased heart rate:
- Sympathetic nervous system
- Hormones
- Exercise
- Decreased blood volume
2.Decreased heart rate
- Parasympathetic nervous system
- High blood pressure or blood volume
- Decreased venous return
120
Resting HR varies due to
size - bigger heart has slower rate
sex - women faster than men
age - young faster than old
exercise (> rate)
fever (> rate)
stimulation of SNS (> rate)
stimulation of PNS (< rate)
hormones (thyroid, epinephrine,
norepinephrine > rate)
121
Stroke Volume (SV)
- volume of blood pumped out of left ventricle per beat average is ~70 mL/beat
* At rest ventricles pumps out only about 67% of blood within them (termed ejection fraction)
---More forcefully ventricles contract – more blood is ejected
122
Preload -
- amount of blood in ventricles at the end of diastole (remember that ventricle fills with blood during resting phase of diastole)
* increased preload stretches ventricles thus increased force of contraction (increased SV and CO)
*decreased preload deceases
stretch in ventricles thus decreased force of contraction (decreased SV and CO)
123
Afterload -
- refers to resistance or opposition
* In order for left ventricle to pump blood into aorta it must push against blood that is already there
- The pressure within the aorta is the resistance or afterload
* A narrow aorta means the left ventricle will need to work harder to overcome resistance
* Same theory holds true for right ventricle
- If pulmonary artery is narrowed then right ventricle needs to work hard to pump bld into pulmonary artery
* Same event occurs – hypertrophy of right ventricle leading to right-sided heart failure (Cor Pulmonale)
* Afterload can be altered by drugs
124
Ejection Fraction (EF)
* When ventricle contracts, it pumps about 67% of it’s volume (thus 33% remains in ventricles)
* Percentage of blood pumped is called the ejection fraction – indicator of cardiac health
- 90% EF with exercise – healthy heart
- 30% EF with walking – very poor heart
125
Stroke Volume (SV
SV – volume of blood pumped out of left ventricle per beat average is ~70 mL/beat
*Can change SV by two ways:
- Starling’s Law
- Inotropic Effect
126
Starling’s Law of Heart
slide 58
127
Inotropic Effect
* Second way of increasing SV is to strengthen the force of contraction without stretching the heart fibers
- ***done by stimulating sympathetic nerves with hormones and drugs
- increase SV Digoxin (+ inotropic effect)
-decrease SV drug Ca2+ channel
blockers (- inotropic effect
128
Ions
***Ions have an effect on HR/contraction
- Reduced Ca2+ depresses heart rate and contractility
- Elevated Ca2+ prolongs contractions – heart failure
- Reduced and elevated K+ causes the heart to beat poorly and irregularly
129
Cardiac Output
*Amount of blood pumped by left ventricle in one minute
Depends on:***
- Heart rate
- Stroke volume
130
Cardiac Output Adjustment
***Body can adjust cardiac output to meet needs
- Heart rate can increase by 250 percent
- Stroke volume can double
