VASCULAR SYSTEM Flashcards
1
Q
Components of the vasculature:
A
Arteries
Arterioles
Capillaries
Venules
Veins
2
Q
______
• Thick walled, extensive elastic tissue & smooth muscle
A
Arteries
3
Q
______
• High pressure
A
Arteries
4
Q
Arteries
• The blood volume contained in them are called the ______
A
stressed volume
5
Q
______
• Smallest branches of the arteries
A
Arterioles
6
Q
______
• Site of highest resistance in the cardiovascular system
A
Arterioles
7
Q
______
• Have smooth muscle walls which have extensive autonomic innervation
A
Arterioles
8
Q
Arterioles
• ______ - in the skin and splanchnic arterioles
A
a1 adrenergic
9
Q
Arterioles
• ______ - in the skeletal muscle arterioles
A
B2 adrenergic
10
Q
______
• Have the largest cross sectional surface area
A
Capillaries
11
Q
______
• Consist of a single layer of cells - thin walled
A
Capillaries
12
Q
______
• Are the site of exchange of nutrients, water & gases
A
Capillaries
13
Q
______
• Are formed from merged capillaries
A
Venules
14
Q
______
• Progressively form larger and larger veins
A
Veins
15
Q
______
• thin walled and are under low pressure
A
Veins
16
Q
______
• Contains the highest proportion of blood in the cardiovascular system
A
Veins
17
Q
Veins
• Blood volume in the veins is called the ______
A
unstressed volume
18
Q
Veins
• Are innervated by ______
A
autonomic fibres
19
Q
______ - greatest cross-sectional area
A
Capillaries
20
Q
______ - Pressure varies bet. systole and diastole
A
Arteries
21
Q
Velocity of blood flow
• Can be expressed by:
V = ______
A
Q/A
22
Q
Velocity of blood flow
v = ______ (______)
Q = ______ (______)
A = ______ (______)
A
velocity, cm/sec
blood flow, ml/min
cross sectional area, cm^2
23
Q
Velocity of blood flow
Therefore, velocity is higher in the ______ (smaller cross sectional area)
is lower in all the ______ - Why?
To maximize the ______
A
aorta, capillaries, exchange of substances
24
Q
Blood flow
• Can be expressed by:
Q = ______
A
🔺P / R
25
Blood flow
Q = ______ (______)
🔺P = ______ (______)
R = ______
blood flow, ml/min
pressure gradient, mmHg
resistance
26
______ flow is in a straight line and ______ flow is not.
Laminar, turbulent
27
______ predicts whether blood flow is turbulent or laminar.
Reynold's number
28
When Reynold's number is increased, there will be ______ and ______ (bruits)
turbulence, audible vibrations
29
Reynold's number is increased by:
______ (low haematocrit, anaemia)
______ (narrowing of a vessel)
reduced viscosity
increased velocity
30
______ (______)
• Describes the distensibility of blood vessels
Capacitance, compliance
31
______ (______)
• Is inversely related to elastance
Capacitance, compliance
32
Capacitance (compliance)
Capacitance is given by:
C = ______
V / P
33
Capacitance
C = ______ (______)
V = ______ (______)
P = ______ (______)
capacitance, ml/mmHg
volume, ml
pressure, mmHg
34
______ (______)
• Describes how volume changes in response to changes in pressure
Capacitance, compliance
35
Capacitance is much greater for ______ than for ______
veins, arteries
36
Changes in venous capacitance changes the ______
venous blood volume
37
decrease in venous capacitance decreases the ______ (______) and increases the ______ (______)
unstressed volume, venous volume, stressed volume, arterial volume
38
Capacitance of arteries ______ with age.
Arteries become stiffer and less distensible)
decreases
39
______
• pulsatile
• Varies during the cardiac cycle
• Systolic pressure
• Diastolic pressure
Arterial pressure
40
Pulse Pressure
______
• most important determinant of pulse pressure
Stroke volume
41
Pulse Pressure
• decrease in ______ due to aging can cause an increase of pulse pressure
capacitance
42
Pulse Pressure
• Generally ______ mmHg
~ 40
43
______
• average arterial pressure with respect to time
Mean Arterial Pressure
44
Mean Arterial Pressure
• ______ + ______ pulse pressure
DBP, 1/3
45
______
• very low
• has a high capacitance
• able to hold a large volume without an increase in pressure
Venous pressure
46
Regulation of arterial blood pressure
Most important mechanisms are:
• the fast ______ mediated ______
• the slower ______ mediated ______
neurally, baroreceptor mechanism
hormonally, renal mechanisms
47
Regulation of arterial blood pressure
Other mechanisms:
Atrial stretch receptors
Local vasoconstrictors and dilators
48
pressure receptors (______) that monitor arterial pressure are present in the:
• ______
• ______
baroreceptors, carotid sinus, aortic arch
49
low-pressure receptors (______)
• walls of ______ at vena caval entrance
• wall of ______ (pulmonary circulation)
cardiopulmonary receptors, right atria, left atria
50
• Increase baroreceptor discharge
- ______ the tonic discharge of sympathetic nerves
inhibits
51
• Increase baroreceptor discharge
- ______ the vagal innervation of the heart
excites
52
Baroreceptor reflex
These neural changes produce:
• Vasodilation
• Venodilation
• Hypotension
• Bradycardia
• Decrease in cardiac output
53
Cardiopulmonary receptors
two types of stretch receptors in the atria:
• those discharging in ______
• those discharging in ______ during atrial filling
atrial systole, late diastole
54
Cardiopulmonary receptors
Effects of increase discharge:
• vasodilatation & a fall in BP
• increase in heart rate
55
Renin
- hormone/enzyme
- synthesized as ______
prorenin
56
Renin
- ______ form
active
57
Renin
- secreted from the ______ of the ______ as renin or prorenin
JG cells, kidney
58
Renin
- produced exclusively by the ______
kidney
59
Renin
- only know function is to ______ and ______
cleave angiotensinogen, form angiotensin-l
60
Juxtaglomerular apparatus
- Comprise of ______, ______ and ______
JG cells, Lacis cells, Macula densa
61
Renin is produced by ______ - located in the media of ______
JG cells, afferent arterioles
62
Renin is also found in ______ that are located in the junction between the afferent & efferent arterioles
lacis cells
63
______ - modified efferent arteriolar cells in close proximity to JG cells
Macula densa
64
Factors that affect renin secretion.
Stimulatory:
Increased sympathetic activity via renal nerves
Increased circulating catecholamines
Prostaglandins
65
Factors that affect renin secretion.
Inhibitory:
Increased Na+ and Cl- absorption across macula densa
Increased afferent arteriolar pressure
Angiotensin lI
Vasopressin
66
______
- Alpha-2 globulin; released by the liver
Angiotensinogen
67
______
- increase by: glucocorticoids, thyroid hormones, estrogens, several cytokines and angiotensin II.
Angiotensinogen
68
______ is formed by endothelial cells and happens in many parts of the body
• conversion of ______ (lungs)
• inactivates ______
Angiotensin Converting Enzyme (ACE), Angiotensin I, bradykinin
69
______
• very short half life of 1-2 min
• active substance
Angiotensin-ll
70
Actions of Angiotensin Il
______
- acts on AT1, receptors
- constricts arterioles and elevate SBP & DBP
Potent vasoconstrictor
71
Actions of Angiotensin Il
Directly acts on adrenal cortex to ______
increase aldosterone secretion
72
Actions of Angiotensin Il
Facilitates the ______ from sympathetic postganglionic neurons
release of NE
73
Actions of Angiotensin II
Contraction of ______ with a decrease in GFR
mesangial cells
74
Actions of Angiotensin II
Has a direct effect on the renal tubules to increase
______.
Na+ reabsorption
75
Actions of Angiotensin II
Acts on the brain to reduce the sensitivity of ______
Baroreceptor reflex
76
Actions of Angiotensin II
Increase ______
thirst
77
Actions of Angiotensin II
Increase ______ and ______ secretion
ADH, ACTH
78
Hormones of the heart & other natriuretic factors
______
• Secreted from the muscle cells in the atria and, to a much lesser extent in the ventricles
ANP
79
Hormones of the heart & other natriuretic factors
______
• Contain secretory granules
• increase in number when ECF expands due to increased Na+ in the body
ANP
80
Hormones of the heart & other natriuretic factors
• ______ - Brain and heart
BNP
81
Hormones of the heart & other natriuretic factors
• ______ - brain, pituitary, kidneys, and vascular endothelial cells (acts in a paracrine fashion)
- promotes natriuresis
CNP
82
Hormones of the heart & other natriuretic factors ANP
Actions:
- Increase GFR by dilating ______ & relaxing ______
afferent arteriole, mesangial cells
83
Hormones of the heart & other natriuretic factors ANP
Actions:
- Acts on the renal tubule to inhibit ______
Na+ reabsorption
84
Hormones of the heart & other natriuretic factors ANP
Actions:
- Increases in ______, leading to extravasation of fluid and a decline in blood pressure.
capillary permeability
85
Hormones of the heart & other natriuretic factors ANP
Actions:
- Relax vascular smooth muscle in ______ and ______.
(______) has a greater dilator effect on veins
arterioles, venules, CNP
86
Hormones of the heart & other natriuretic factors ANP
Actions:
- Inhibit ______ secretion
renin
87
Hormones of the heart & other natriuretic factors ANP
Actions:
- Counteract the pressor effects of ______
catecholamines
88
Peripheral chemoreceptor reflex
• Peripheral chemoreceptors found in the ______ & ______ Bodies
Aortic, Carotid
89
Peripheral chemoreceptor reflex
Peripheral chemoreceptors
• Have a very high ______
blood flow
90
Peripheral chemoreceptor reflex
Peripheral chemoreceptors
• Activated by: low ______, ______ and ______
PaO2, PCO2, pH
91
Peripheral chemoreceptor reflex
Peripheral chemoreceptors
• Stimulated by ______
hypoxic hypoxia
92
Peripheral chemoreceptor reflex
Peripheral chemoreceptors
• Main effects are on ______, but also leads to ______
respiration, vasoconstriction
93
Peripheral chemoreceptor reflex
Peripheral chemoreceptors
Direct effects of chemoreceptor activation:
• ______
• Increased ______ from adrenal medulla (increases HR and BP)
Hypoxia, catecholamines
94
Central chemoreceptors
When intracranial pressure increases, the pressure on the Vasomotor Center along with ______ and ______ increases its discharge.
• rise of systemic ______
• reflex reduction in ______ (through baroreceptor reflex)
local hypoxia, hypercapnia, blood pressure, heart rate
95
Central chemoreceptors
Therefore, increased ICP manifests as ______ and ______
hypertension, bradycardia
96
______
• The capacity of tissues to regulate their own blood flow
Autoregulation
97
Autoregulation
• Most vascular beds have an ______ to compensate for moderate changes in perfusion pressure so that blood flow remains relatively ______.
intrinsic capacity, constant
98
Autoregulation
• mainly ______ as well as mesentery, skeletal muscle, brain, liver, myocardium.
kidney
99
Autoregulation
Two theories for this:
• ______
- Constant blood flow at varying arterial pressure
• ______
- Vasodilator metabolites are produced as perfusion pressure is reduced
Myogenic autoregulation
Metabolic theory of autoregulation
100
______
- Causes arteriolar dilatation & venous constriction
Histamine
101
______
- Resulting in local edema
Histamine
102
______
- Released in response to tissue trauma
Histamine
103
______
- Exactly like histamine
Bradykinin
104
______
- Causes arteriolar constriction
Serotonin
105
______
- Released in response to vessel damage to prevent blood loss
Serotonin
106
Prostaglandins
- ______ is a vasodilator in several vascular beds
Prostacyclin
107
Prostaglandins
- ______ are vasodilators
E-series prostaglandins
108
Prostaglandins
- ______ are vasoconstrictors
F-series prostaglandins
109
Prostaglandins
- ______ is a vasoconstrictor
Thromboxane A2
