Cardiovascular physiology Flashcards
(175 cards)
1
Q
What happens once the arterial baroreceptors start firing?
A
the medullary cardiovascular center receive it and decrease sympathetic outflow to heart, arterioles and veins; and increase parasympathetic outflow to heart
2
Q
What do arterial baroreceptors do?
A
respond to changes in pressure when walls of vessel stretch/relax, increase in MAP increases rate of firing of baroreceptors
3
Q
What stage does pulse pressure disappear? (aorta, arterioles, capillaries etc.)
A
arterioles
4
Q
What is hypotension?
A
abnormally low blood pressure (think: hypO- lOw) resulting in fainting, dizziness and shock
5
Q
What is hypertension?
A
chronically increased arterial blood pressure resulting in heart attack, stroke or kidney damage
6
Q
How is blood pressure measured?
A
systole/diastole
7
Q
What does compliance mean?
A
the ability of a vessel to stretch/inflate and increase in pressure due to greater pressure inside the vessel than outside
8
Q
What do lymph nodes do?
A
function in immune response
9
Q
What are lymph vessels?
A
one-way valves that ensure lymph flows just to the right atrium and empty into the venous system
10
Q
What are lymphatic capillaries?
A
a single layer of endothelial cells that have water-filled channels permeable to interstitial fluid components including proteins that enter by bulk flow
11
Q
What are varicose veins?
A
when the vein walls are weak and so its valves do not function properly causing blood to pool and vessels swell
12
Q
How many valves/fold/leaflets do veins have?
A
2 that project inwards to prevent backflow of blood to capillaries , blood travels in one direction only (compartmentalize)
13
Q
What are veins?
A
high capacitance vessels or vessels that are able to store large volumes of blood
14
Q
Which hold more blood veins or arteries?
A
veins because walls thicker
15
Q
Where does the transition point between filtration and reabsorption lie?
A
closer to venous end of capillary
16
Q
What are the 4 forces called the Starling forces?
A
interstitial fluid, capillary, hydrostatic pressure and colloid osmotic pressure
17
Q
What is it called when fluid is favored to move out of the capillaries in interstitial fluid colloid osmotic pressure?
A
negligible
18
Q
What is interstitial fluid colloid osmotic pressure?
A
small amount of plasma proteins may leak out of the capillaries and return to the lymphatic system
19
Q
What is blood colloid osmotic pressure?
A
because plasma proteins in the capillaries are too large they cannot easily cross through the capillary walls and will pull water into the capillaries
20
Q
When fluid moves into capillary by way of interstitial fluid hydrostatic pressure it is said to be what?
A
negligible (will not contribute significantly to bulk flow)
21
Q
What is interstitial fluid hydrostatic pressure? what direction does it favor movement of fluid?
A
fluid pressure exerted on the outside of the capillary wall by interstitial fluid (think: interstitial fluid is on the outside so they will exert pressure outside), favors movement into capillary (H–>L, high pressure in interstitial fluid more than capillary)
22
Q
What is capillary hydrostatic pressure? what direction does it favor fluid to move?
A
pressure exerted on inside of capillary walls by blood, it favors fluid to move out of capillary( H–>L)
23
Q
What is hydrostatic pressure?
A
pressures that drive fluid movement (bulk flow) into and out of the capillary
24
Q
What is reabsorption in capillary exchange?
A
movement of protein-free plasma from interstitial fluid into the capillary
25
What is filtration in capillary exchange?
the movement of protein-free plasma from the capillary out to the interstitial fluid
26
What is the function of bulk flow?
to distribute extracellular fluid (plasma and interstitial fluid) volume NOT the exchange of nutrients and metabolic end products across capillary walls
27
What is bulk flow?
the movement of protein-free plasma across the capillary wall
28
What is transcytosis?
use of vesicles (e.g. fused vesicle channel that forms a water-filled channel across the cell) to cross endothelial cells
29
How is blood altered to tissues according to needs (e.g. at rest vs during strenuous exercise)?
through capillary beds
30
What is a metarteriole (takes part in microcirculation)?
not true capillary that is made of smooth muscle cells and connects arterioles to venules. they change diameter to regulate flow
31
What are precapillary sphincters (take part in microcirculation)
have rings of smooth muscle and are at the entrance to a capillary. they alter blood flow but have no innervation just respond to local factors (e.g. oxygen and carbon dioxide levels)
32
What is microcirculation?
circulation of blood through smallest vessels
33
What are sinusoidal capillaries?
discontinuous capillaries that are flattened and irregularly shaped having large fenestrae with gaps between cells. The basement membrane is thin or absent. They exchange water and large solutes.
34
What are fenestrated capillaries?
capillaries that have fenestrate (pores) that penetrate endothelial lining and either have a diaphragm connecting different fenestra or not. They are also surrounded by basement membrane. They rapidly exchange water and solutes(small peptides)
35
What are continuous capillaries?
when endothelial cells form an uninterrupted tube, surrounded by complete basement membrane. They exchange water, small solutes, lipid-soluble material but do not exchange blood and plasma proteins
36
What are intercellular clefts? (in capillaries)
a narrow water-filled space at the junctions between cells
37
What is the function of capillaries?
to exchange material between blood and interstitial fluid
38
What are capillaries?
a thin walled vessel that are one endothelial cell thick. They have no smooth muscle or elastic tissue allowing for more rapid exchange of material
39
Steps of active hyperemia
an increase in metabolic activity of organ (e.g. exercise), decrease in oxygen, increase in metabolites in organ interstitial fluid, arteriolar dilation in organ, increased blood flow to organ
40
What are local controls/ active hyperemia?
mechanisms by which an organ can alter its own arteriolar resistance and as a result regulate its own blood flow without the use of nerves or hormones
41
What does epinephrine from the adrenal medulla do vasoconstrict or vasodilate the arterioles?
both
42
What does nitric oxide do to arterioles vasoconstrict or vasodilate?
vasodilate
43
What does norepinephrine do vasoconstrict or vasodilate arterioles?
vasoconstrict
44
What is vasoconstriction of arterioles?
contraction of arteriolar smooth muscle that decreases blood flow to organs
45
What is vasodilation of arterioles?
relaxation of arteriolar smooth muscle that will increase blood flow to organs
46
Structure of arterioles?
have an abundance of smooth muscle cells that regulate blood flow to organs, and determine MAP (blood pressure)
47
Rank from greatest pressure to least: arteries, capillaries, veins, venules, arterioles
arteries, arterioles, capillaries, venules, veins
48
What is the difference in appearance between the large vein and large artery?
large vein (inferior vena cava) have few layers of smooth muscle and connective while the large artery (aorta) they have many layers of smooth muscle and connective tissue
49
What is afterload?
any increase in arterial pressure will decrease stroke volume, because this is a "load" that the contracting ventricles have to work against. How hard the heart must work to eject blood in this situation is afterload
50
What is the relationship between the heart filling and the cardiac muscle fibers?
as the fibers stretches more (decreasing space between thick and thin filaments, allowing more cross bridges and increases the attraction of troponin for calcium and release of calcium by sarcoplasmic reticulum) the heart fills more
51
What is the Frank-starling mechanism?
the relationship between EDV and SV, increasing diastolic filling will increase EDV which will increase cardiac fiber length and create a greater force during contraction and greater SV
52
Heart rate during parasympathetic activity?
decreased
53
Heart rate during increase sympathetic activity?
increased
54
What is cardiac output?
the amount of blood pumped by each ventricle in one minute
Heart rate X Stroke volume (blood pumped out during systole)
units: L/min
55
What structures are involved in parasympathetic innervation of the heart?
atria, SA node, AV node
| * not the ventricles
56
What structures are involved in sympathetic innervation of the heart?
atria, ventricles, SA node and AV node
57
When blood is flowing normally through valves does it make a sound?
No, it is laminar
58
What does the dub sound mean?
that diastole is about to start
59
How is the dub sound made?
by the closure of the semilunar valves
60
What is the second heart sound?
dub
61
What does the lub sound mean?
that systole is starting
62
How is the lub sound created?
with the closure of the AV valves
63
What is the first heart sound?
Lub
64
How does the right ventricle differ from the left in systole?
right ventricle develops lower pressures than left, because the myocardium at right ventricle is not as thick as left and does not generate as much pressure when it contracts
65
In what situation does stroke volume decrease and increase?
decrease during rest and increase during exercise
66
How is stroke volume how is it measured?
EDV- ESV
67
What is the end-systolic volume (ESV)?
amount of blood in each ventricle at the end of ventricular systole (in mL)
68
What is the end-diastolic volume (EDV)?
the amount of blood in each ventricle at the end of ventricular diastole (in mL)
69
Blood flows from a region of (higher/lower) __ pressure to a region of _ (higher/lower) pressure?
higher to lower
70
What is the atrial kick?
at the end of diastole/ ventricular filling when the atria contract
71
What is ventricular filling?
AV valves open, blood flows into ventricles from atria. Ventricles receive blood passively (atria are relaxed)
72
What is isovolumetric ventricular relaxation?
all heart valves closed, blood volume remains constant, pressures drop
73
What is the two parts of diastole?
isovolumetric ventricular relaxation and ventricular filling
74
What are the 2 parts of the cardiac cycle?
Systole- ventricular contraction and blood ejection
| Diastole- ventricular relaxation and blood filling
75
What is stroke volume?
volume of blood ejected from each ventricle during systole
76
What is ventricular ejection?
pressures in ventricles exceeds that in arteries, semilunar valves open and blood ejected into the artery. Muscle fibers of ventricles shorten
77
What is isovolumetric ventricular contraction?
when all heart valves are closed, blood volume in ventricles remains constant, pressures rise. Muscle develops tension but cannot shorten
78
Steps of systole
isovolumetric ventricular contraction and ventricular ejection
79
What does cardiac cycle length measure?
period from one heartbeat to next
80
What is tropomyosin?
structure that partially covers the myosin-binding site on actin at rest (preventing cross-bridges from making contact with actin)
81
What is troponin?
structure in cross-bridge (actin and myosin) that contains binding sites for calcium and tropomyosin, and regulates access to myosin binding sites on actin
82
How does ECC (excitation-contraction coupling) happen in cardiac muscle?
1) Calcium ions found in high concentrations in the ECF and low in cytoplasm regulate the contraction of cardiac muscle
2) calcium ions will bind to ryanodine receptors that will release calcium from the sarcoplasmic reticulum into cytoplasm (calcium-dependent calcium release)
3) contraction
83
What are t-tubules or transverse tubules?
invaginations of sarcolemma; transmit depolarization of membrane into interior of muscle cell (contain L-type calcium channels)
84
What is the contractile unit of muscle cells?
sarcomeres (actin and myosin )
85
What is the sarcoplasmic reticulum?
stores and releases calcium when muscle cell is stimulated
86
What is the sarcolemma?
cell membrane of muscle cell
87
What is complete AV node block?
when there is no synchrony between atrial and ventricular electrical activities, have no QRS complex or T wave or its not in the correct order or increased time between P-wave and QRS (because of His bundle)
88
What is a partial AV node block?
when there is a heart block impairing the conduction between atria and ventricles where every 2nd P-wave is not followed by QRS complex
89
What is the sequence that ECG measures? (e.g. P QRS T or T QRS P etc.)
P QRS T
90
What is the T-wave in ECG recording?
ventricular repolarization
91
What is the QRS-complex in ECG recording?
spread of depolarization that happens quickly across ventricles while the atria repolarize simultaneously
92
What is the P-wave in ECG recording?
spread of depolarization across atria
93
What is the electrocardiogram (ECG, EKG)?
a graphic recording that measures electrical activity in heart as a whole to help diagnose problems with heart's conduction system (not mechanical)
94
steps of generating an action potential in a SA node (with corresponding channels per step)
1. Pacemaker potential- F-type channels (unusual gating behavior) funny , T-type (transient) only open briefly
2. Depolarization- L-type channels (L for long-lasting)
3. Repolarization - K+ channels (returns to negative potential/ downward) and activates pacemaker
95
What is the pacemaker potential/ SA node action potential?
is not steady/true in its membrane potential but instead undergoes gradual depolarization/ slow depolarization to threshold. It can have regular spontaneous generation of action potentials without external influence from hormones or nerves
96
What is cardiac action potential?
when there is a closing and opening of ion channels that change the permeability of the cell membrane to Na+, K+ and Ca 2+ ions
97
What are slow action potentials? and where can they be found?
slower depolarization
| found in the SA node and AV node
98
What is the fast action potential? and where can it be found?
rapid rate of depolarization
| found in the atrial myocardium, ventricular myocardium, bundle of His and Purkinje fibers
99
What are the 2 types of action potentials?
fast and slow ( nothing to do with heart beating fast or slow)
100
What is wolff-parkinson-white syndrome?
when someone is born with an extra accessory pathway that will bypass the AV node and move from the atria to ventricles faster than usual causing rapid heart rate or tachycardia
101
Where is the only electrical connection between atria and ventricles at?
the AV node and bundle of his
102
What is the AV nodal delay?
a 100msec delay that ensures atria depolarize and contract before the ventricles giving them time to fully fill up before contracting
103
What is the sinoatrial (SA) node?
the cardiac pacemaker (initiates the action potentials that will set the heart rate)
104
What is membrane potential?
the difference in electrical potential between the interior and exterior of cell
105
What are conducting cells (autorhythmic)?
they initiate and conduct the action potentials responsible for contraction of the contractile myocytes (muscle cells), they do not contribute to hearts overall contraction
106
What do contractile cells do?
they do not initiate action potentials but are responsible for the mechanical work of pumping like propelling the blood
107
What are the 2 types of cardiac muscle cells (myocytes)?
contractile and conducting
108
What is automaticity/ autorhythmicity?
when the cardiac muscle contracts as a result of action potential it generated by itself with no neural or hormonal stimulation
109
What causes heart muscle cells to contract?
action potentials
110
What is functional syncytium?
if one cell is excited the excitation will spread over both ventricles or atria
111
What is syncytium?
an arrangement in which the cardiac muscle cells (myocytes) communicate and act together
112
What is myocardial infarction?
a heart attack- caused by loss of blood supply to heart killing the muscle
113
What is angina?
chest pain or discomfort as a result of reduced blood flow to heart muscle
114
What are results of coronary artery disease?
angina or myocardial infarction
115
What is coronary artery disease?
when there is plaque (fat, cholesterol etc.) accumulation in arteries and they become hardened and narrow (atherosclerosis) reducing lumen in vessel and blood flow
116
What is diastole?
when both ventricles are relaxed/ not contracting
| myocardial blood flow peaks
117
What is systole?
when both left and right ventricles contract
| myocardial blood flow almost ceases
118
What is the coronary sinus?
collection of veins joined together to form a large vessel that collects blood from the myocardium of the heart
119
What are coronary veins?
drain into the coronary sinus, which empties into the right atrium
120
What are coronary arteries?
arteries that originate at the aortic sinuses at the base of the ascending aorta
121
What are the valve rings?
rings made of cartilage that function as the site of attachment for the heart valves
122
What are the valves?
thin flaps of flexible, endothelium-covered fibrous tissue attached at the base (ends) to the valve rings (surround the valves)
123
What is the cardiac skeleton?
dense inactive ( blocks spread of electrical impulses from atria to ventricles- important for proper depolarization) connective tissue that separates atria from ventricles
124
Do arterial (semilunar) valves have chordae tendineae and papillary muscles?
No
125
What are the papillary muscles?
cone shaped muscles that when they contract they cause the chordae tendineae (hold valve in place) which are attached to it to become taut (rigid)
126
What is the chordae tendineae?
tendinous-type tissue that extends from edges of the cusps to the papillary muscles
127
Where is the bicuspid valve located?
left side the one with the 2 leaflets/cusps
128
Where is the tricuspid valve located?
on the right side (the one with the 3 leaflets/cusps)
129
How do valves function?
it provides a unidirectional flow of blood ( which is important because that means the blood flowing out will not mix with the new blood entering the heart thereby not wasting unnecessary energy) through heart and open/closes passively due to pressure gradients
130
What are the 4 valves of the heart?
* named after destination*
pulmonary (semilunar) valve- connects right ventricle to pulmonary trunk
aortic (semilunar) valve- connects left ventricle to aorta
left AV (bicuspid/mitral) valve - connects left atrium to left ventricle
right AV (tricuspid) valve- connects right atrium to right ventricle
131
How is the myocardium arranged and why?
in interlacing bundles of cardiac muscle fibers arranged spirally around heart, this is because when the heart contracts and shortens it can efficiently push blood upwards toward the exit of the major arteries
think: when you squeeze a bottle of ketchup you wrap your hands around it to squeeze maximum out
132
What is the myocyte?
a cardiac muscle cell that is shaped like a Y and joined end to end by other adjacent myocytes making it look striated with a single nucleus per cell but many mitochondria
133
Why is the left ventricle thicker than the right one?
because it has a thicker layer of myocardium
134
What is the endocardium?
endothelium covering inner surfaces of heart and heart valves that provides a smooth surface for blood to flow over
135
What is the myocardium?
the muscular wall that houses the cardiac muscles cells or myocytes that contract and relax when heart is beating, blood vessels and nerves
136
What is the epicardium?
the outer protective layer of the heart that is made up of simple squamous cells and underlying connective tissue that is connected to the myocardium
137
What structures comprise the heart wall?
the epicardium, myocardium and endocardium
138
Differences between right and left ventricular wall
the left ventricular wall (round in shape) is thicker than the right (looks like a pouch) as it withstands higher pressures than the right
139
What is cardiac tamponade?
compression of heart chambers due to excessive accumulation of pericardial fluid
140
What is pericarditis?
inflammation of the pericardium
141
What is the pericardial cavity?
contains the pericardial fluid that helps decrease friction as the heart beats
142
What is the serous pericardium?
a layer that is composed of cells that secrete fluid (pericardial fluid)
143
What is the fibrous pericardium?
it is a connective outer layer tissue that prevents sudden rapid overfilling of heart as it does not stretch readily . It also provides protection of the heart by stabilizing it in the thoracic cavity by attaching to structures in chest like coastal cartilage and sternum
144
What are the functions of the pericardium?
stabilization of the heart in thoracic cavity because the outer layer of the pericardium is linked to the thoracic cavity, protects heart from trauma or infection, it lubricates layers of heart as it contracts/twists through pericardial fluid and it limits overfilling of the chambers
145
What is the pericardium?
fibrous sac composed of 3 layers (fibrous pericardium, parietal, visceral) surrounding the heart and roots of great vessels
146
Series vs parallel flow?
Series is following the system so pulmonary to systemic or vice versa with heart in between, Parallel is flow within the systemic circuit so most organs are supplied separately by different arteries
147
What does the right heart do?
receives blood from systemic and pumps to pulmonary
148
What does the left heart do?
it receives blood from the pulmonary circulation and pumps into systemic circulation
149
What does the systemic circulation do?
pumps blood to and from the rest of the body. When the blood enters the tissues it is oxygenated but when it leaves its poorly oxygenated (oxygen diffuses from the blood into the body tissues)
150
What does the pulmonary circulation do?
it pumps blood to and from the gas exchange surfaces of the lungs. When the blood initially enters the lungs they are poorly oxygenated but when it leaves the lungs it leaves oxygenated
151
What are the 2 serial circuits of the circulatory system?
Pulmonary and systemic circulation
152
What is the septa?
muscular wall of separation between left and right interatrial septum(thin like atria) and interventricular (thick like ventricles) septum, or the poorly oxygenated side and the highly oxygenated side
153
What are the ventricles?
thick walled chambers that are responsible for forward propulsion of blood
154
What are the atria?
they are thin-walled low pressure chambers that receive blood returning to the heart
155
What are the 4 chambers of the heart?
2 atria and 2 ventricles
156
What does it mean if our circulatory system is closed?
blood will remain within our heart chambers or blood vessels at all times. This generates greater pressures when it contracts allowing the blood to pump faster
157
What direction do veins move?
towards heart
158
What are capillaries?
smallest blood vessel, that transport blood between small arteries and venules exchanging material
159
What are arteries?
small branching vessels that go away from the heart with high resistance
160
What are the components of the CV (Cardiovascular) system?
the heart as the pump, the blood vessels as the pipes and the blood as the fluid
161
What are the functions of the cardiovascular system?
To deliver oxygen, nutrients and remove waste products of metabolism that can build up an be dangerous. It provides fast chemical signaling to cells by circulating hormones or neurotransmitters. Maintain body temperature or thermoregulation. Work with inflammatory and host defense responses.
162
Which has less friction vessels with a small or large diameter?
large
163
What is viscosity?
friction between molecules of a flowing fluid
164
What are factors that effect the resistance to blood flow?
viscosity, length of vessel and diameter of vessel
165
What is the formula for flow?
change in P/ R
P= pressure difference between two fixed points (this is what determines flow not the absolute pressure)
R= resistance to flow (P>R for flow to happen)
166
Why do we have a cardiovascular system?
because diffusion is not enough to supply nutrients across large distances so this circulation provides a steep concentration gradient in close proximity to every cell allowing for rapid exchange of material between blood and cells
167
Series vs parallel flow?
Series is following the system so pulmonary to systemic or vice versa with heart in between, Parallel is flow within the systemic circuit so most organs are supplied separately by different arteries
168
What is pericarditis?
inflammation of the pericardium
169
How do valves function?
it provides a unidirectional flow of blood ( which is important because that means the blood flowing out will not mix with the new blood entering the heart thereby not wasting unnecessary energy) through heart and open/closes passively due to pressure gradients
170
What is the P-wave in ECG recording?
spread of depolarization across atria
171
What are t-tubules or transverse tubules?
invaginations of sarcolemma; transmit depolarization of membrane into interior of muscle cell (contain L-type calcium channels)
172
How is stroke volume how is it measured?
volume
173
What are continuous capillaries?
when endothelial cells form an uninterrupted tube, surrounded by complete basement membrane. They have the lowest permeability and exchange water, small solutes, lipid-soluble material but do not exchange blood and plasma proteins
174
What are continuous capillaries?
when endothelial cells form an uninterrupted tube, surrounded by complete basement membrane. They exchange water, small solutes, lipid-soluble material but do not exchange blood and plasma proteins
175
What do lymph nodes do?
function in immune response
