Midterm I stuff Flashcards
(130 cards)
1
Q
what compartments recieve blood from veins
A
atria
2
Q
what part of heart ejects blood into arteries
A
ventricles
3
Q
What are the major systemic veins?
A
sup and inf vena cava
4
Q
why are ventricles larger w thicker walls
A
because they are stronger pumps
5
Q
wharts the major systemic artery
A
aorta
6
Q
major vessels of pulm circuit?
A
r and L pulm arteries and veins
7
Q
which atria is larger
A
the right is larger, thinner, more anterior
8
Q
What are right and left ventricles seperated by?
A
interventricular septum
9
Q
what are the valves between the atria and ventricles
A
Atrioventicular valves (AV valves)
Tricuspid - on right side
Bicuspid/mitral - on left side
10
Q
What are the valves between ventricles and pulmonary arteries
A
Semilunar valves (Also tricuspid)
- Pulmonary valves - between r ventricle and pulm trunk
- aortic valve: between left ventricle and aorta
11
Q
what is the purpose of valves
A
keep blood flowing in one direction
12
Q
Blood flows in response to - —- gradients
A
pressure
13
Q
what happens when pressure in ventricle is high (greater than aorta or atrium)
A
Pushes aortic valve open, if greater than atrium closes atrioventricular valves (tricuspid or biscupid(mitral)
14
Q
what happens when pressure in aorta is greater than ventricle
A
closes aortic semilunar valve
15
Q
what happens if pressure in the atrium is greater than ventricle
A
Opens AV valves
16
Q
Describe the steps of blood flow thru the heart
A
1) blood in systemic capillaries delivers oxygen to body
2) systemic veins bring deoexygentaed blood back to right atrium
3) Blood passes to right ventricle thru tricuspid valve
4) then thru pulmonary valve to pulmonary veins (pulmonary trunk)
5) to pulmonary capillaries in lungs where blood becomes oxygenated
6) pulm veins returns oxygenated blood to left atrium
7) blood goes from left atrium thru bicuspid (mitral valve) to left ventricle
8) left ventricle pumps thru aortic valve to aorta
9 ) aorta delivers blood to systemic capillaries and body
17
Q
what are the two types of cells in the myocardium
A
myocytes - majority (99%)
pacemaker cells - 1%
18
Q
what is the source of force production of the heart muscle?
A
myocytes
19
Q
what generates spontaneous, rythmic action potentials
A
pacemaker cells
20
Q
do pacemaker cells contribute to the contractile force of the heart
A
no - just a signal for myocyte contraction
21
Q
what joins myocytes together?
A
intercalated discs
22
Q
what connects pacemaker cells to contractile cells?
A
Intercalated discs
23
Q
what are intercalated discs made of?
A
Desmosomes: hold the cells together
Gap junctions; allow ions to pass rapidly form one call to another
24
Q
What are the steps of the cardiac conduction system?
A
1) SA node generates AP potentaial which spreads to atrial cells and AV node
2) after AV node delay, AP goes to AV bundle and then to right and left bundle branches
3) ap spreads from bundle branches along purkinje fibers to contractile cells of ventricles
25
What is the purpose of the delayed conduction thru the AV node?
Allows atria to fully depolarize (and contract) before the ventricles, giving ventricles time to fill up w blood.
26
steps of pacemaker action potentails
1) Slow initial depol phase: HCN channels open in response to membrane hyperpolarization --> this leads to more Na+ in then K+ out leads to depolarization to threshold
2) Full depol Phase: Ca2+ via ca channels leads to depol phase
3) Repol phase: K+ out via K+ channels, repolarization
4) Min potential phase: HCN open again in resp to hyperpol from K+ flowing out and cycle repeats
27
What inititiates the HCN channels to open in pacemaker action potentials
during the final phase K+ flow out and hyperpolarize opening HCN channels
28
Action potentials are transmitted from ___ to ___ through _____
from pacemaker cells to myocytes thru gap junctions
29
what are the steps of myocyte action potentials
1) rapid depolarization phase: Na+ rushes into cell via Na+ channels
2) initial repolarization phase: Na+ channels close, K+ open, K+ leaves causing some repolarization
3) plateau phase: Ca2+ comes, via opening og ca channels, in while K+ is going out, causing balance:
- Lengthens AP to 200-300: Keeps HR slow enough to allow time for heart to fill w blood before next contraction
4) Repolarization phase: Na+ and Ca2+ channels closee as K+ continue to exit = repol
30
What does the plateau phase allow for in myocyte action potentials?
allows enough time for the heart to fill w blood before the next contraction and prevents tetanus (another AP)
31
what does chronotropic mean?
Heart rate
32
Does the parasmpathetic ns have a positive or negative chronotopic effect?
negative
33
Does sympathetic nervous system have a positive or negative chronotropic effect
positive
34
does contraction and relaxation of the myocytes need to be in perfect synchrony?
Yes. and facilitate filling and blood flow from atria ventricles, and then out via the aorta or
pulmonary arteries
35
what is preload?
The amount of stretch of the sarcomeres in the ventricular muscle cells (myocytes). Before contraction
36
What is the perfect sequency an synchrony a result of? (3 reasons)
1) delay at av node
2) gap unction allow eletrical signal to spread quick thru myocytes
3) orientation of myocytes
37
How does increased preload affect blood pressure?
Increase in preload increases edv -->incr SV, Incr CO, Incr blood pressure
38
where are the electodes on a 3 lead ecg
RIght arm (-, -) , left arm( +, -), left leg (+, +)
39
What are the 3 diffferent waves of the ECG and what does each represent
P wave - atrial depolarization
QRS complex - Ventricular depolarization (masking atrial repol)
T wave - Ventricular repolarization
40
What does the R-R interval represent on an ECG
duration of cardiac cycle
41
what does P-Q represent
duration of atrial repol and AV node delay
42
What does Q-T interval represent?
entire duration of ventricular action potential
43
what does the s-t segment represent
ventricular plateau phase
44
The cardiac cycle describes not electrical events but ____ events of the heart
mechanical
45
what rep contraction what rep relaxation of heart
contraction - systole
relaxation- diastole
46
Do atrial and ventricular systoles and diastoles occur at same or different times why?
The occur at different times due to the AV node delay.
47
Do both sides of the heart work at different times or simulataneosly
simulataneosly
48
what are the 4 main phases of the cardiac cycle
filling, contraction, ejection, relaxation
49
What horomone binds inside a cell and why?
Lipid based/steroid molecules because they are hydrophobic therefore can pass thru membrane
50
if BP drops below normal range waht happens in terms of symp ns
Increased activity of sup ns
51
What happens during the ventricular filling phase?
Blood flows down the pressure gradient from atria to ventricles.
Atria in systole
Ventricles in diastole
AV valves open
semilunar valves are closed
52
Isovolumetric contraction Phase
ventricular systole
atrial diastole
all valves closed
53
what the state of the atria and ventricles during ventricular ejection. Which valves open and closed. FLow of blood?
ventricles in systole
atria in diastole
AV valves closed
SL valves open
Blood is ejected into pulm artery and aorta
54
What is end diastolic volume?
total amount of blood in ventricles at the end of ventricular diastole
55
At rest how much blood is pumped into each ventricle
70ml
56
what is end systolic volume? How much is it at rest
the amount of blood remaining in ventricle at the end of ventricular ejection
at rest about 50ml
57
what the state of the atria and ventricles during isovolumetric Relaxation:. Which valves open and closed. FLow of blood?
ventricles in diastole
atria in diastole
all valves closes
blood is not being ejected or enter - remains constant
58
what is stroke volume?
Volume of blood ejected out of left ventricle in one heart beat
59
what is cardiac output
volume of blood pumped out of left ventricle in one minute (L/min)
60
What is venous return>
volume of blood returning to heart in one min
61
whats the formula for SV? Resting is?
EDV-ESV. 70mL
62
What is formula for CO? whats resting?
SV x HR - 70x70 = 4900ml (around 5 L)
63
What are the 3 main factors that affect stroke volume?
Preload, contractility, afterload
64
What is preload?
amount of stretch of sarcomeres in ventricular myocytes before contraction - det by EDV
65
How does preload affect SV? 2 factors that influence edv?
Higher preload = Higher volume of blood in ventricle (EDV) = more stetch on ventricle myocytes and more potential for actin-myosin overlap e
1) length of time ventricle spends in diastole
2) amount of bood returning to heart from systemic circuit (venous return)
66
How does contractility increase SV?
- Greater force of contraction = more blood ejected = lower ESV = greater SV
67
what are inotropic agents?
agents that affect contractility
68
What is afterload?
the force ventricle must overcome in order to eject blood into arteries
69
How does afterload increase SV?
Lower afterload = ventricle pumping against lower resisistane = lower ESV
70
What happens to the three factors that affect stroke volume when stroke volume decrease?
low preload (muscle cells less stretched) , low contractility (heart contracts more weakly), high afterload (ventricle pumping against a higher resistance)
71
What are chronotropic agents?
Factors that influence HR
72
Under normal conditions what determines HR?
The rate at which SA node generates AP
73
What is a positive chronotropic agent? what does it include?
ANything that increases rate at which SA node fires (incr HR)
includes sympathetic nervous system, horomones, elevated body temp
74
What is a negative chronotropic agent? and examples
Anything that decrease the rate of SA nod firing
included parasympathetic nervous system and decreased body temp
75
How does sympathetic NS reg Cardiac output
Epinephrine and norepinephrin incr HR and contractility of myocytes which increases SV and HR. positive chronotropic and Inotropic effect.
76
How does parasympathetic NS regulate CO?
Acetylcholine targets SA node and decreases HR
- Negative chronotropic effectf
77
what are presuure resevoirs
arteries
78
what are volume resevoirs
veins
79
What is the site of variable resistance
the arterioles
80
are there more arteries or veins
veins
81
what holds more blood, arteries or veins?
veins hold much more blood than arteries (70%)
82
what are the wall layers of arteries and veins from innermost to outermost
innermost - tunica intima
middle - tunica media
outer - tunica externa
83
what layer of the arteries and veins contains smooth muscle?
tunica media
84
what does contraction of the arteries or veins lead to vs relaxation?
contraction --> vasoconstiction --> decreased diametre
Relaxation --> vasodilation ---> increases diameter
85
veins have ____ wals, ____ elastic fibres, ____ smooth muslcle and ____ lumen
Most arteries have much thicker _______ (wall) and more ___ laminae (due tonhigher bp the ssee)
VEINS = thinner walls, less elastic fibres, less smooth muscle, larger lumen
Most arteries have much thocker tunica media more internal and external elastic laminae.
86
Whats a main role of tunica media
controlling blood flow and blood pressure
87
what is the fucntion of elastic arteries? primarily made up of?
Condict blood under high pressure to organs. Elastic laminae.
88
what type of arteries are pulmonary arteries
elastic
89
what arteries reg bP and control blood flow to organs?
muscular arteries
90
wha tunics are arterioles made of?
all 3
91
what is the main function of arterioles?
control blood to tissues, feed capillaries
92
Main fucntion of venules?
drain capillary beds
93
main function of veins
return blood to heart
94
what is blood flow thru capillary bed based on?
tissue needs - skel msucles need more o2 more capillary beds
95
what is blood flow thru tissues regulate dby?
1) opening/closing of precapillary sphincters
2) vasoconstriciton/dilation of arterioles
96
What is the equation for blood flow?
Blod pressure gradient (deltap)/resistance
- bp gradient creates the blood flow
- the total resistance is the impedence to blood flow
97
what is the current (I) equation
= voltage gradient (delta v) (delta v)/ Resistance
98
What is the main determinant of flow rate of blood?
pressure gradient
99
What is blood pressure?
outward force that the blood exerts on the walls of blood vessels (mmHg)
100
What are the three things resistance is determined by?
Vessel radius, length, viscocity
101
What is the velocity of blood flow equation?
1 / cross sectional area
102
Total cross sectional area increase as artries bracnh into...
smaller vessels
103
As total cross sectional area increase what happens to velcocity
velocity slows down
104
where is blood velcocity slowest? why?
in capillaries, to allow more time for effective gas and nutrient exchange
105
What is systolic pressure - at rest?
pressure of blood against artery wall during systole (120mmHg)
106
what is Diastolic pressure - at rest?
the pressure of blood against the artery walls during diastole - 80mmHg
107
what is the pulse pressure?
difference betwee systolic and diastolic BP - Sp-Dp - 120-80 = 40
108
What dos systemic arterial bp represent?
the driving pressure of blood thru arteries -MAP
109
what is the MAP equation
MAP = diastolic pressure + 1/3 (systolic pressure – diastolic pressure)
110
when is pulse pressure gone on the graph? what does the black line mean?
when it reaches the arterioles -- cap -- venules -- to veins-- venacavae
black line is MAP
111
What are the three factors that determine BP?
Peripheral resistance, CO, blood volume
112
as peripheral resistance increase what happens to BP?
also increases
113
what are the three things that impact peripheral resistance?
Blood viscocity - more viscous more molecule resistance to motion - blood has high viscocity bc of protein and cells
Blood vessel length - longer blood vessel = gerater Resistance = more pressure to propela long long vessel
Blood vessel radius - as radius increases resitance decreases, so inverse
114
How does hight blood viscocity impact BP?
more viscous= more resistance to motion = more peripheral resistance = higher BP
115
what is a reason that resistance in pulm circuit is less than systemic
Blood vessels are longer in systemic so reseitance is grater
116
How does cardiac output impact BP
Increase in cardiac output leads to increase in BP
117
How does blood volume imapct BP?
when blood contains more water, volume invrease, increase in blood volume means increase in pressure therfore increase in BP
118
which circiuit does pressure remain relatively low and stable?
pulmonary
119
in systemic circuit whre is the highest pressure? where is the lowest
highest is arteries than arterioles, lowest is venules and veins
120
where does MAP decrease rapidly
arterioles
121
2 mechanisms of venous return
valves - ensure one way flow
Skeletal muscle pump - skel muscle squeeze deeper veins to propel to heart (vasoconstirciton)
122
What three systems is BP under regualtion by?
nervous, endocrine and urinary
123
where is short term maintenance of BP? where is long term maintenance? what sytems?
Short term - nervous ssystem - ANS. - periph resistance and CO ( think HR and SV) - Norepinephrine and epinephrin
Long term - kdineys and endocrine sytem
- increases the water lost as urine changinging blood volume
horomones act on kdiney to manage fluid retention eg ADH
124
give an example of how the endocrine system plays a role in the cardiovascular.
Endocrine releases ADH (anti-diuretic horomone) which alter fluid retention in the kidney therfore changinf blood volume and impacting blood pressure.
125
How does Nervous system impact HR?
symp neurons release epinephrine and norepinephrine which increase HR and contractility and therfore cardiac output -
also cause vasocontriviton of arteriooles which increases perip resistance
126
Which ssytem in the ANS decreases bp and why?
Parasympthetic decrease heart rate decreaseing CO and therefore blood pressure
127
what are baroreceptors?
specialized mechanoreceptors found in walls of aortic arch and common carotid artery which respond to stretch in the artery wall
128
where are baroreceptors found?
aortic arch and common carotid artery
129
what is the baroreceptor reflex (in terms of increase in Bp)
Increased BP --> increased wall stretch --> increaseed firing of AP via cranial nerves of sns --> to medulla for integration --> output to lower bp
130
