Week 8 - Cardiovascular System Flashcards
(114 cards)
1
Q
what is the pulmonary circuit ?
A
- right ventricle
- pulmonary artery
- lungs
- pulmonary veins
- left atrium
2
Q
what is the systemic circuit ?
A
- left ventricle
- aorta
- body
- vena cava
3
Q
what is microcirculation ?
A
the collective term for the arterioles, capillaries, and venules
4
Q
what is flow directly proportional to ?
A
pressure difference
5
Q
what is flow indirectly proportional to ?
A
resistance
6
Q
what is the equation for flow rate ?
A
Flow = pressure difference / resistance
7
Q
what are the units of flow rate ?
A
mL/min
8
Q
what are the units of pressure ?
A
mmHg
9
Q
what is resistance directly proportional to ?
A
- viscosity
- length of the tube
10
Q
what is resistance indirectly proportional to ?
A
4th power of the radius of the tube
11
Q
what is the equation of resistance ?
A
R=8Lη/(πr^4 )
12
Q
define myocardium
A
the wall of the heart, composed of cardiac muscle cells
13
Q
define endothelium
A
thin layer of cells that line the inner surface of cardiac chambers
14
Q
define interventricular septum
A
muscular wall that separates right and left ventricles
15
Q
where is the tricuspid valve ?
A
right AV valve (3 fibrous cups)
16
Q
where is the bicuspid valve ?
A
left AV valve (2 fibrous cups)
17
Q
what are the characteristics of cardiac muscle ?
A
- 1-2 nuclei
- large mitochondria
- arranged in layers, tightly bound together
18
Q
define conduction system ?
A
initiated the heartbeat and helps spread action potential throughout the heart
19
Q
sympathetic fibres - innervate and release…
A
entire heart and norepinephrine
20
Q
parasympathetic fibres - innervate and release…
A
node cells and acetylcholine
21
Q
what are the receptors for norepinephrine ?
A
beta-adrenergic
22
Q
what are the receptors for acetylcholine ?
A
muscarinic type
23
Q
how are contractions of the heart triggered ?
A
depolarisation of the plasma membrane
24
Q
what is the order of the conduction system ?
A
- SA Node
- Atrial muscle cells
- AV Node
- BoH
- L and R bundle branches
- L and R Purkinje fibres
- Ventricular muscle cell
- depolarization = contraction
25
what is the P wave in an ECG ?
current flow during atrial depolarisation
26
what is the QRS complex in an ECG ?
result of ventricular depolarisation
27
what is the T wave in an ECG ?
result of ventricular depolarisation (obscured by QRS complex)
28
what is the full name of an ECG ?
electrocardiogram
29
define systole
ventricular contraction
30
define diastole
ventricular relaxation
31
what happens during isovolumetric ventricular relaxation ?
AV valves are closed, ventricular volume not changing
32
what happens during ventricular filling ?
AV valves open, blood fills ventricles
33
what happens during isovolumetric contraction ?
all valves are closed, ventricles are contracting
34
what happens during ventricular ejection ?
when the pressure in the ventricles exceeds that of the aorta and pulmonary trunk, ejection of the blood occurs
35
Early Diastole : AV Valve
closed
36
Late Diastole : AV Valve
open
37
Systole : AV Valve
closed
38
Early Diastole : Aortic Valve
closed
39
Late Diastole : Aortic Valve
closed
40
Early Systole : Aortic Valve
closed
41
Late Systole : Aortic Valve
open
42
define heart rate
the number of times the heart beat per minute
43
things that increase HR are...
positive chronotropic factors
44
things that decrease HR are...
negative chronotropic factors
45
sympathetic NS...
increases HR
46
parasympathetic NS...
decreases HR
47
define stroke volume
the difference between end diastolic volume (EDV) and end systolic volume (ESV)
48
how do you calculate SV ?
SV = EDV - ESV
49
define cardiac output ?
the amount of blood pumped out of each ventricle in one minute
50
how do calculate CO ?
CO = HR x SV
51
what is the basic concept of Frank Starling's Law ?
the ventricle contracts more forcefully during systole, when it has been filled to a greater degree during diastole
52
according to Frank Starling's Law, what occurs during the stretching of the myocardium ?
decrease in spacing between thick and thin filaments = more cross bridges = increase sensitivity to Ca2+
53
what is the basic concept of contractility ?
norepinephrine acts on beta-adrenergic receptors to increase ventricular contractility.
54
other than norepinephrine, what other chemical increases contractility ?
plasma epinephrine
55
what is the ejection fraction ?
EF = SV / EDV
56
define 'atrial kick'
the small amount of blood forced into the ventricles during atrial depolarization
57
define heart rate
the number of times the heart beats per minute
58
what increases heart rate ?
positive chronotropic factors
59
what decreases heart rate ?
negative chronotropic factors
60
what does the sympathetic nervous system do ?
increase HR
61
what does the parasympathetic nervous system do ?
decreases HR
62
define stroke volume
the difference between end diastolic volume and end systolic volume
63
define cardiac output
the amount of blood pumped out of the left ventricle in one minute
64
how do you calculate cardiac volume ?
CO = HR x SV
65
what is the concept of Frank Starling's Law ?
the ventricle contracts more forcefully during systole when it has been filled to a greater degree during diastole
66
according to Frank Starling's Law, what does stretching of the myocardium cause ?
decrease in spacing between thick and thin filaments = more cross bridges
67
according to Frank Starling's Law, what does an increase in cross-bridges cause ?
increased sensitivity to Ca2+
68
what is the concept of contractility ?
norepinephrine acts on beta-adrenergic receptors to increase ventricular contractility
69
what is the ejection fraction ?
EF = SV / EDV
70
what are the 2 types of arteries ?
- elastic arteries
| - muscular arteries
71
what are elastic arteries ?
- near the heart
| - carry blood for circulation
72
elastic artery: example
aorta
73
what are muscular arteries ?
- deliver blood to specific organs
74
muscular artery: example
renal artery
75
define compliance
how easily a structure stretches
76
how do you calculate compliance ?
compliance = ΔVolume / ΔPressure
77
what fraction of SV leaves the arteries during systole ?
1/3 - the rest is driven out when the artery recoils
78
define systolic pressure (SP)
maximal arterial pressure reached during peak ventricular ejection
79
define diastolic pressure (DP)
minimum arterial pressure that occurs just before ventricular ejection
80
define pulse pressure
the difference between SP and DP
81
define mean arterial pressure (MAP)
average pressure during the cardiac cycle
82
what are arterioles ?
the smallest arteries, they are controlled by neural, hormonal and local chemicals
83
what happens if arterioles contract ?
blood flow is diverted AWAY from their tissue
84
what happens if arterioles dilate ?
blood flow is increased TOWARDS their tissues
85
define intrinsic tone
basal level of control of arterioles
86
what happens to arterioles surround muscles during exercise ?
dilate
87
what happens to arterioles surrounding the digestive system during exercise ?
constrict
88
what happens to the arterioles surrounding the brain during exercise
remain constant at all times
89
what are the 2 local controls of arterioles ?
- active hyperemia
| - response to injury
90
define active hyperemia
increase in blood flow when metabolic activity (exercise) is increased
91
what happens in the arterioles in response to injury ?
- tissue injury causes substances to be released by local cells
- substances make arteriolar smooth muscle relax
- increased blood flow
92
what are the two extrinsic controls of arterioles ?
- sympathetic nerves
| - hormones
93
how do sympathetic nerves control arterioles ?
dilation can be achieved by decreasing the rate of sympathetic activity to the basal level of control
94
what are the 3 hormones that control arterioles ?
- epinephrine
- angiotensin II
- vasopressin
95
how does epinephrine control arterioles ?
vasodilates depending on the tissue
96
how does angiotensin II control arterioles ?
constricts most arterioles
97
how does vasopressin control arterioles ?
constricts most arterioles
98
define cappilary
the smallest blood vessels, where gas and nutrient exchange takes place
99
what are the 3 types of capillaries ?
- continuous capillaries
- fenestrated capillaries
- sinusoidal capillaries
100
define continuous capillary
- found in skin, muscle
- most common kind
- tight junctions
101
define fenestrated capillary
- more permeable
| - intestines, hormone-producing tissue, kidneys
102
define sinusoidal capillary
- only one with an incomplete basement membrane
| - liver, bone marrow, lymphoid tissue
103
define angiogenesis
the process through which capillaries grow and develop
104
define precapillary sphincter
ring of smooth muscle which relaxes and contract in response to local metabolic factors
105
what is blood velocity dependent on ?
cross-sectional area of the vessel type (high in capillaries)
106
where is there a high concentration of O2 and glucose during exercise ?
capillary
107
where is there a high concentration of CO2 during exercise ?
muscle cell
108
in the systemic circuit, what drives venous return ?
pressure difference between the veins and right atrium
109
what is the pressure difference between the veins and right atrium ?
- veins = 10-15mmHG
| - right atrium = 0mmHG
110
what are the 2 main functions of the veins ?
- acts as low-pressure channels, returning blood to the heart
- maintain peripheral venous return
111
how do the veins maintain peripheral venous return ?
by altering their diameter in response to blood volume
112
what are the 2 factors that determine venous pressure ?
- amount of blood in veins
| - compliance of the walls
113
how much of total blood volume is on the veins ?
approx. 60%
114
what does constriction of the veins cause ?
increase in forward flow
