Cardiovascular Flashcards
1
Q
What are the receiving chambers of the heart
A
The atria
2
Q
What is the orientation of the heart in the chest
A
Right side is right cranial
Left side is left caudal
3
Q
What attaches the heart to the sternum
A
The sternopericardial ligament
4
Q
Which side of the heart has a thinner wall and why
A
The right side
Because it is a lower pressure circuit
5
Q
How are the fibers of the myocardium arranged
A
Longitudinally, radially and transversely
6
Q
What is the annulus fibrosus
A
Fibrous tissue that surrounds the valves
7
Q
Which ventricle pushes blood to the lungs
A
Right ventricle
8
Q
How much of the cardiac output does the heart receive
A
5%
9
Q
What beat is palpable
A
The apex beat
10
Q
What cell type mostly makes up the myocardium
A
Cardiomyocytes
11
Q
Describe the endocardium
A
Single layer of flattened endothelial cells with a basement membrane
12
Q
What is the only path for electrical conduction through the annulus fibrosis
A
The AV node
13
Q
What two structures form the base of the heart
A
The atria and auricles
14
Q
What ventricle forms the apex of the heart
A
The left ventricle
15
Q
What are the papillary muscles
A
Insertions for chordae tendineae of the AV valves
16
Q
The pulmonary trunk emerges to the ___ of the aorta
A
Left
17
Q
What is the purpose of the foramen ovale
A
Permits blood flow between right and left atria
18
Q
What is the purpose of the ductus arterious
A
Permits blood flow from the pulmonary trunk to the aorta
19
Q
What is the purpose of the ductus venosus
A
Allows blood returning from the placenta to bypass the liver
20
Q
What does the umbilical vein carry
A
Oxygenated blood from the placenta
21
Q
What generates cardiac action potentials
A
The pacemaker cells of the SA node
22
Q
What two events lead to the closure of the ductus arteriosis
A
Change in O2 tension & pressure and drop in fetal prostaglandins
23
Q
What is the role of the AV node in cardiac excitation
A
It signals are delayed which allows the atria to be fully depolarized before ventricular excitation beings
24
Q
What are the 3 vessel linings of the heart
A
Tunica intima, media and adventitia
25
What is the sarcolemma
The cell membrane of cardiac muscle (includes outer polysaccharide layer)
26
What is a T-tubule and what do they do
The invagination of a cardiac cell membrane - they facilitate transmission of depolarization through the muscle fiber
27
Where is the sarcoplasmic reticulum located and what is its function
Around myofibrils (cylindrical arrangements of contractile proteins)
It stores/releases Ca ions
28
What is an adherence junction
Attachment of sarcomere via actin to cell membrane
29
What is a desmosome
A strong intracellular connection
30
What is a gap junction
It permits the spread of contractions from cell to cell
31
What are purkinje cells and what are their primary function
They are specialized cardiomyocytes with few contractile proteins
Their main function is CONDUCTION
32
What are the four major protein types of a sarcomere
1. Actin
2. Tropomyosin
3. Troponin
4. Myosin
33
What are the two primary contractile proteins of a sarcomere
Actin and myosin
34
What is the Z disc
Marks the boundaries of each sarcomere
35
What is the I band
Thin filaments spanning the z disc (light)
36
What is the a band
Dark bands where thick and thin filaments over lap
37
What is the H zone
Center of sarcomere - thick filaments only
38
What is diastole and when does it start
The heart filling with blood
It starts with ventricular relaxation
39
At what cardiac phase do the atria contract
During late diastolic filling (squeezes blood into an already almost full ventricle)
40
What phase of the cardiac cycle do we hear the S3 and S4 heart sound in horses
Early diastolic filling (S3) and late diastolic filling (S4)
41
What phase of the cardiac cycle makes the P wave
Atrial contraction
42
What is systole
The contraction of the ventricle
43
What is the isovolumic contraction phase of systole
When the ventricle is contracting but the semilunar and AV valves are shut
44
What is the ejection phase of systole
When semilunar and AV valves open as the ventricle contracts and blood enters the great vessel
45
What makes the S1 sound
The AV valves snapping shut at the start of ventricular contraction
46
What makes the S2 sound
The semilunar valves snapping shut after ventricular contraction (start of diastole/ventricular relaxation)
47
Atrial systole is part of...
Cardiac diastole
48
What is the stroke volume
The volume of blood ejected from one ventricle during systole
49
Cardiac output =
Stroke volume x Heart rate
50
Stroke volume =
End diastolic volume - end systolic volume
51
The ECG represents what?
The summation of all action potentials in the heart over time
52
The P wave represents __
Atrial depolarization
53
The QRS complex represents __
Ventricular depolarization
54
The T wave represents __
Ventricular repolarization
55
Explain atrioventricular synchrony
The ventricles will only contract if an impulse has travelled through the AV node, once the atria have depolarized and emptied as much as possible into the ventricle
56
Why does the SA node fire spontaneously?
Because of the rhythmic inflow of calcium ions and outflow of potassium ions
57
Why do AV, purkinje, and myocardial cells not depolarize spontaneously even though they can?
Because the SA node makes them do it faster than their inherent rhythm
58
Explain excitation-contraction coupling in the heart
When a myocardial cell depolarizes, it will cause an influx of Ca ions that triggers the release of more Ca that will bind to troponin C and initiate contraction
59
What affect do sympathetic nerve fibers have on heart rate
They increase it by increasing the inflow of calcium to cause more depolarizations
60
What are the chemical effectors of sympathetic control to the heart
Noradrenaline and adrenaline
61
What affect do parasympathetic nerve fibers have on heart rate
They decrease it because it decreases the inflow of calcium and funny currents and increasing the flow of potassium, causing slower/less depolarization
62
What are the chemical effectors of the parasympathetic control to the heart
Acetylcholine (closes Ca channels and opens K channels)
63
What does noradrenaline bind to
B1- receptors
64
What does Ach bind to
M2 receptors
65
What happens to calcium after the ventricles contract and are repolarizing
Calcium detaches from troponin C and is pumped back into the SR by the ATPase pump SERCA
66
What are the 4 major determinants of cardiac output
1. Contractility
2. Preload
3. Afterload
4. Compliance
67
Define the frank starling mechanism
The more filling (preload), the higher the end diastolic volume AND is energy independent
68
Which form of vasculature have the thickest walls and why
Arterioles because they provide vascular resistance and direct blood flow
69
Which form of vasculature have the thinnest walls and why
Capillaries to allow for exchange
70
Upstream of the arterioles blood pressure is ___
High
71
Which valves maintain diastolic blood pressure in the aorta and pulmonary arteries
Semi-lunar
72
Why is the velocity of blood flow slow across capillaries
To allow more time for diffusion
73
What is a key difference between conducting arteries and muscular arteries
Conducting arteries have more elastin and muscular arteries have less
74
Which form of vasculature contributes the most to blood pressure and how
Arterioles
They can change their diameter to regulate which tissues are perfused
75
What is Poiseuille's law and what does it mean
R = 1/r^4
It means that a small reduction in radius leads to a huge increase in resistance
76
What sympathetic mediator induces arterioconstriction and what does it bind to
Noradrenaline
Alpha-1 receptors
77
What sympathetic mediator induces arteriodilation and what does it bind to
Adrenaline
Beta-2 receptors
78
Where can you find fenestrated capillaries
1. Renal glomeruli
2. Endocrine organs
3. Intestinal cells
(where lots of exchange is required)
79
Where are sinusoidal capillaries found
1. Spleen
2. Liver
(where the most exchange happens)
80
At the arteriole end of capillaries there is net ___, and at the venule end there is net ___
Filtration (fluid moving out)
Reabsorption (fluid moving in)
81
What regulates blood flow into individual capillaries and what do they do
Pericytes - mesenchymal cells that squeeze endothelial cells to increase capillary resistance and prevent capillary flow
82
Explain AV shunting
If capillary resistance is too high, blood will flow through metarterioles directly into venules
83
The contraction of ___ propels blood through veins
The tunica media
84
What prevents the back flow of blood in veins
Valves formed from folds of the tunica intima
85
What is the formula for blood pressure
BP = CO x R
86
During systole, BP is ___
High
87
During diastole, BP is ___
Lower
88
Name 2 instances in which pulse pressure is increased
Patent ductus arteriosus
Aortic valve insufficiency
89
Arteriole diameter is controlled by ___
Alpha-1 and beta-2 receptors of the sympathetic nervous system
90
What are sinuses
Specialized veins in areas with very low pressure, like the brain, that return blood back to the heart
91
A __ diastolic pressure is required to pump blood to various organs
High
92
Define pulse
a pressure wave created by the difference in the systolic and diastolic pressure
93
What are the two principle levels of cardiovascular control
1. Neurohumoral/central/systemic
2. Local tissue
94
Which nerve is the parasympathetic nerve of the cardiovascular system
The vagus nerve
95
Heart rate increases when vagal tone is ___
Reduced
96
When is sinus arrhythmia markedly noticeable vs absent?
In respiratory disease
Absent in cardiac disease
97
What are baroreceptors
Mechanoreceptors in the carotid sinus and aortic arch
98
Which nerve(s) relays baroreceptor impulses to the brain
Glossopharyngeal (CNIX) and Vagus (CNX)
99
How is plasma volume regulated intrinsically?
By pressure natriuresis (if your blood pressure goes up you will produce more urine)
100
How is plasma volume regulated extrinsically
Neurohormones (RAAS, ADH, and ANP/BNP)
101
Define the myogenic response
Distension of vessels will increase the frequency of spontaneous APs in vascular smooth muscle and cause it to constrict
102
By-products of metabolism can cause __
Vasodilation
103
Alveolar hypoxia results in ___
Vasoconstriction (blood is shunted away from the poorly ventilated areas)
104
Where is the vasomotor center found in the brain
The medulla oblongata
105
In order for hypertension to exist, there must be __
A deficiency in pressure natriuresis
106
Define shock
When tissue perfusion & oxygen delivery are insufficient to meet metabolic demands of tissues
107
What are 3 causes of tissue hypoperfusion (types of shock)
1. Not enough blood
2. Blood not being pumped efficiently
3. Blood not going to the right place (inappropriate vasodilation or obstruction)
108
Define hypovolemic shock
Loss of circulating volume
109
List 4 causes of hypovolemic shock
1. Hemorrhage
2. Vomiting/diarrhea
3. Burns
4. Severe dehydration
110
Define distributive shock
When there is a maldistribution of blood/blood is not going to the right place
111
List 2 causes of distributive shock
1. Vasodilation
2. Obstruction
112
Define cardiogenic shock
Failure of the heart to pump effectively
113
What are two less common types of shock
1. Metabolic
2. Hypoxemic
114
What are the two responses of the sympathetic nervous system to hypovolemic shock
1. Activation of alpha-adrenergic receptors
2. Activation of beta1-adrenergic receptors
115
What is different about cats and hypovolemic shock
Cats lack an appropriate compensatory response so they only develop mild tachycardia or develop bradycardia
116
Define compensatory shock
Compensatory mechanisms are activated to maintain blood flow to organs
117
What are two neurohormonal responses to shock
1. Activation of RAAS
2. Release of vasopressin
