Chapter 18/19 Cardiovascular System Flashcards
(110 cards)
1
Q
an increase in the volume of a container filled with air would have what effect on the pressure of the container
A
- increase the pressure
- decrease the pressure*
- no effect
- a temporary effect
2
Q
which of the following delivers air to the lobes of the lungs
A
- primary bronchi
- secondary bronchi* -> lobar bronchi
- tertiary bronchi
- terminal bronchioles
3
Q
heart anatomy
A
- approx the size of a fist
- in the mediastinum between second rib and fifth intercostal space
- on the superior surface of diaphragm
- to the left of the midsternal line
- anterior to the vertebral column posterior to the sternum
- enclosed in pericardium, a double walled sac
4
Q
pericardium
A
- superficial fibrous pericardium- protects, anchors, and prevents overfiling
- deep two layered serous pericardium:
- parietal layer
- visceral layer
- separated by fluid pericardial cavity (decreases friction)
5
Q
parietal layer of heart
A
- lines the internal surface of the fibrous pericardium
- serous pericardium
6
Q
visceral layer of the heart
A
- epicardium
- on external surface of the heart
- serous pericardium
- visceral layer of the pericardium
7
Q
myocardium
A
- cardiac muscle
- layer that contracts
- connective tissue of heart
- anchors cardiac muscle fibers
- supports great vessels and valves
- limits spread of action potentials to specific paths
8
Q
endocardium
A
- lines chambers
- is continuous with vessels
9
Q
chambers
A
- 4 chambers
- two atria- receiving chambers, partition called interatrial septum
- two ventricles- pumping chambers, separated by the interventricular septum
10
Q
atria: receiving chambers (entraceway)
A
- 3 veins entering right atrium: superior vena cava, inferior vena cava, coronary sinus (from heart)
- veins entering left atrium- right and left pulmonary veins
11
Q
ventricles: discharging chambers
A
- vessel leaving the right ventricle- pulmonary trunk (artery) to lung has limited oxygen
- vessel leaving the left ventricle- aorta to body- has oxygen
12
Q
pathway of blood through the heart
A
- the heart is two side by side pumps
- equal volumes of blood are pumped to the pulmonary and system circuits*
- pulmonary circuit (right)- short, low pressure circulation
- systemic circuit (left)- blood encounters much resistance in the long pathways
- size of the ventricles reflect these differences
13
Q
coronary circulation
A
- blood supply to the heart muscle itself
- collateral routes provide additional routes for blood delivery
- O2 utilization- 70% to 80% extracted from blood supply
- if vigorous exercise must increase blood flow by dilating coronary vessels
- practically one capillary per muscle fiber
- impairment in flow = angina
- partial/complete blockage of coronary = myocardial infarction (heart attack)
14
Q
coronary artery disease
A
- CABG (coronary artery bypass graft)- great saphenous vein
- balloon angioplasty
- cardiac stents- metal mesh tubes
15
Q
atrioventricular (AV) valves
A
- close when ventricles contract
- prevent back flow
- tricuspid valve (right)
- mitral (bicuspid) valve (left)
16
Q
semilunar (SL) valves
A
- aortic semilunar valve (left)
- pulmonary semilunar valve (right)c
16
Q
semilunar (SL) valves
A
- aortic semilunar valve (left)
- pulmonary semilunar valve (right)
17
Q
chordae tendineae (collagen strings)
A
- anchor AV valve cusps to papillary muscles
- prevents valves from turning inside out
18
Q
valve disease
A
- faulty valves make heart work harder
- either blood leaks backward or flow is restricted through valves
- murmurs, mitral valve prolapse, aortic valve stenosis
19
Q
which of the following statements is true
A
- all arteries transport oxygen rich blood
- the right side of the heart is the systemic circuit pump
- equal volumes of blood are pumped to the pulmonary and system circuits at any moment*
- the left side of the heart pumps blood to the lungs
- all of the above is true
20
Q
blood being pumped out of the left ventricle enters the ____
A
- pulmonary artery
- aorta*
- coronary sinus
- venae cavae
- pulmonary vein
21
Q
skeletal vs cardiac MM
A
- stimulation- skeletal MM is stimulated by nerve endings; cardiac MM are self-excitable, intrinsic conduction system
- contraction- skeletal MM contract from motor unit; cardiac MM contracts as a unit or not a tall (gap junctions)
- absolute refractory- cardiac MM has longer period, prevents tetanic contractions (stop pumping action)
22
Q
cardiac MM contraction
A
- depolarization
- transmission of depolarization wave
- excitation-coupling
- repolarization
23
Q
depolarization
A
- Na channels open and Na rushes in
- membrane potential rises from -90mV to +30mV
24
transmission of depolarization wave
- opens special calcium channels in membrane to release 20% of calcium
- then T tubules cause SR to release the remaining calcium needed for contraction
25
excitation-coupling
-Ca provides signal for cross bridge activation (calcium channel blockers- HTN)
26
repolarzation
-Ca channels close and K channels opens and returns to resting voltage
27
energy requirements
- heart is exclusively aerobic
- has more mitochondria than skeletal MM
- cardiac MM able to use whatever nutrient is available. including lactic acid
- danger of inadequate blood supply to heart is not lack of nutrients BUT lack of O2
28
sequence of excitation
- cardiac pacemaker cells are found:
- 1. sinoatrial node- generates impulses
- 2. atrioventricular node (delay for atria to finish contracting
- 3. atrioventricular bundle (bundle of HIS) (only electrical connection between atria and ventricle)
- 4. right and left bundle branches (intraventricular septum)
- 5. subendocardial conduction network (purkinje fibers)- depolarize the contractile cells of both ventricles
29
arrhythmias
- irregular heart rhythm due to defects in intrinsic conducting system
- atrial fibrillation (a-fib) and ventricular fibrillation (v-fib), can be life threatening if not treated within minutes
30
extrinsic innervation of the heart
- heartbeat is modified by the ANS
- cardiac centers are located in the medulla oblongata
- cardioaccelerator center- innervates SA and AV nodes, heart muscle, and coronary arteries through sympathetic neurons
- cardioinhibitory center- inhibits SA and AV nodes through parasympathetic fibers in the vagus nerves (note no heart muscle)
31
electrocardiography
- electrocardiogram (ECG or EKG)- a composite of all the action potentials generated by nodal and contractile cells at a given time
- 3 waves:
- p wave- depolarization of SA node (atria)
- QRS complex- ventricular depolarization
- T wave- ventricular repolarization
32
elevated ST segment
- MI
| - prolonged QT interval could increase risk of ventricular arrhythmias
33
heart sounds
- two sounds: lub-dup -> associated with closing of heart valves
- first sound occurs as AV valves close and signifies beginning of ventricular systole (contraction)
- second sound occurs when SL valve close at the beginning of ventricular diastole (relaxation)
- heart murmurs- abnormal heart sounds most often indicative of valve problems
- swishing sound since valves are incompetent
34
ventricular filling
- takes place in mid-to-late diastole (relaxation)
- AV valves are open, SL valves are closed
- 80% of blood passively flows into ventricles
- atrial systole occurs, delivering the remaining 20%
- end diastolic volume (EDV): volume of blood in each ventricle at the end of ventricular diastole, maximum amount of blood
35
ventricular systole (contraction)
- atria relax and ventricles begin to contract
- rising ventricular pressure results in closing of AV valves
- isovolumetric contraction phase (all valves are closed)
- in ejection phase, ventricular pressure exceeds pressure in the large arteries, forcing the SL valves open
- end systolic volume (ESV)- volume of blood remaining in each ventricle
36
isovolumetric relaxation
- occurs in early diastole
- ventricles relax
- backflow of blood in atria and pulmonary trunk closes SL valves
- ventricles again are closed chambers because all valves are closed
37
this valve is found between the right atrium and the right ventricle
- mitral
- tricuspid*
- bicuspid
- semilunar
- aortic
38
which of the following structures is an exception to the general principle surrounding blood vessel oxygenation levels
- pulmonary artery
- aorta
- pulmonary veins
- both a and c*
- all of the above
39
atrial repolarization occurs during this period of time seen on a ECG
- P wave
- QRS complex*
- T wave
- S-T segment
40
cardiac output (CO)
- volume of blood pumped by each ventricle in one minute
- CO=heart rate (HR) x stroke volume (SV)
- HR=number of beats per minute
- SV=volume of blood pumped out by a ventricle with each beat
- cardiac output is main indicator if the supply (circulation) is meeting demand (O2 at tissues)
- with endurance training, the SA node comes under greater influence of acetylcholine (PNS) which has slowing effect on HR
41
regulation of stroke volume
- SV=EDV-ESV (amount of blood in ventricle during diastole vs and the volume of blood remaining after contraction)
- three main factors affect SV:
- preload
- contractility
- afterload
42
preload
- degree of stretch of cardiac muscle cells before they contract (frank starling law of the heart). Enhanced cardiac filling
- contributor to stroke volume
- at rest, cardiac muscle cells are shorter than optimal length
- slow heartbeat and exercise increase venous return
- increase venous return distends (stretches) the ventricles and increases contraction force**
43
contractility
- regulation of stroke volume
- contractile strength at a given muscle length
- positive inotropic agents increase contractility:
- 1. increased Ca2+ influx due to sympathetic stimulation
- 2. hormones (thyroxine, glucagon, and epinephrine)
- 3. drug digitalis
- negative inotropic agents decrease contractility:
- 1. acidosis
- 2. increased extracellular K+
- 3. calcium channel blockers
44
afterload
- regulation of stroke volume
- pressure that must be overcome for ventricle to eject blood
- hypertension increases afterload -> results in increased ESV and reduced SV
45
regulation of heart rate
- sympathetic stimulation of pacemaker cells
- norepinephrine causes the pacemaker to fire more rapidly (and at the same time increases contractility)
- parasympathetic NS- inhibits pacemakers
- the heart at rest exhibits vagal tone
- parasympathetic activity has little or no effect on cardiac contractility
- hormones
- ions
- age, gender, exercise, and temperature
46
chemical regulation of heart rate: hormones
- epinephrine from adrenal medulla enhances heart rate and contractility
- thyroxine increases heart rate and enhances the effects of norepinephrine and epinephrine
47
chemical regulation of heart rate: intra- and extracellular ion concentrations
- Ca and K
| - must be maintained for normal heart function
48
other factors that influence heart rate
- age- faster in fetus, declines with age
- gender- females faster than males
- exercise- increases HR, training decreases overall
- body temperature- heart increases HR
49
the lub-dup heart sounds are produced by _________
- the wall of the atria and ventricles slapping together during a contraction
- the blood hitting the walls of the ventricles and arteries, respectively
- the closing of the atrioventricular valves (lub) and the closing of the semilunar valves (dup)*
- the closing of the semilunar valves (lub) and the closing of the atrioventricular valves (dup)
50
atrial systole occurs ____ the firing of the sinoatrial node
- before
- after* i think
- simultaneously with
- alternately with
51
predict what would happen to the end systolic volume (ESV) if contraction force were to increase
- it would decrease*
- it would increase
- it would remain constant
- ESV is not affected by contraction force
52
blood vessels
- delivery system of dynamic structures that begins and ends at the heart
- arteries- carry blood away from the heart; oxygenated except for pulmonary circulation and umbilical vessels of a fetus (branch)
- capillaries- contact tissue cells and directly serve cellular needs
- veins- carry blood towards the heart (converge)
53
structure of blood vessel walls
- arteries and veins- tunica intima, tunica media, and tunica externa
- lumen- central blood containing space
- capillaries- endothelium with sparse basal lamina
54
three groups of arteries
- elastic arteries- near heart (stretch) -> able to withstand high pressure (aorta)
- muscular arteries- distribute to organs, thick tunica media -> named via organ (ex. hepatic AA)
- arterioles- smallest of arteries
55
capillaries
- microscopic blood vessels
- walls of thin tunica intima - one cell thick
- size allows only a single RBC to pass at a time
- most tissues are rich in capillaries except tendons and ligaments and absent for cartilage
- consist of two types of vessels:
- 1. vascular shunt- (metarteriole- thoroughfare channel)
- 2. true capillaries- branch of the metarteriole or terminal arteriole
56
blood flow through capillary beds
- precapillary sphincters regulate blood flow into true capillaries
- regulated by local chemical conditions and vasomotor nerves
- sphincters open- blood flows through true capillaries
- sphincters closed- blood flows through metarteriole thoroughfare channel and bypass true capillaries
57
veins
- have thinner walls, larger lumens compared with corresponding arteries
- blood pressure is lower than in arteries
- called capacitance vessles (blood reservoirs)- contain up to 65% of the blood supply
- adaptations that ensure return of blood to the heart:
- 1. large diameter lumens offer little resistance
- 2. valves prevent backflow of blood
58
venous sinuses
- flattened veins with extremely thin walls
| - e.g. coronary sinus of the heart and dural sinuses of the brain
59
vascular anastomoses
- interconnections of blood vessels
- arterial anastomoses provide alternate pathways (collateral channels) to a given body region -> common at joints, in abdominal organs, brain, and heart
- vascular shunts of capillaries are examples of arteriovenous anastomose
- venous anastomoses are common (saphenous vein in CABG)
59
vascular anastomoses
- interconnections of blood vessels
- arterial anastomoses provide alternate pathways (collateral channels) to a given body region -> common at joints, in abdominal organs, brain, and heart
- vascular shunts of capillaries are examples of arteriovenous anastomose
- venous anastomoses are common (saphenous vein in CABG)
60
blood flow
- volume of blood flowing through a vessel, an organ, or the entire circulation in a given period, based on needs
- measured as ml/min
- equivalent to cardiac output (CO) for entire vascular system
61
blood pressure (BP)
- force per unit area exerted on the wall of a blood vessel by the blood
- expressed in mmHg
- the pressure gradient provides the driving force that keeps blood moving from higher to lower pressure areas
62
resustance
- opposition to flow
| - measure of the amount of friction blood encounters
63
3 important sources of ressitance
- blood viscosity- the stickiness of the blood due to formed elements and plasma proteins
- total blood vessel length- the longer the vessel, the greater the resistance encountered
- blood vessel diameter- arterioles are the major determinants of peripheral resistance
- abrupt changes in diameter or fatty plaques from atherosclerosis dramatically increase resistance
- viscosity can be adjusted with meds
64
relationship between blood flow, blood pressure, and resistance
- F=change in P / R
- blood flow (F) is directly proportional to the blood pressure gradient (change in P)
- if increase in BP -> blood flow speeds up
- blood flow is inversely proportional to peripheral resistance (R)
- if R increases, blood flow decreases
- R is more important in influencing local blood flow because it is easily changed by altering blood vessel diameter
65
systemic blood pressure
- the pumping action of the heart generates blood flow
- pressure results when flow is opposed by resistance
- systemic pressure is:
- highest in the aorta
- declines throughout the pathway
- is 0 mmHg in the right atrium
- the steepest drop occurs in arterioles
66
systolic pressure
-pressure exerted during ventricular contraction (120)
67
diastolic pressure
- lowest level of arterial pressure (70-80)
| - indicates peripheral resistance
68
pulse pressure
-difference between systolic and diastolic pressure
69
mean arteriole pressure (MAP)
- -pressure that propels the blood to the tissues
- MAP= slightly less than the average between systolic and diastolic pressure
- because diastole is longer than systole
- if BP = 120/80 then MAP = 96
- pulse pressure and MAP both decline with increasing distance from the heart
70
blood pressure: capillary and veins
- capillary:
- ranges from 15-35 mmHg
- low capillary pressure is desirable
- high BP would rupture fragile, thin walled capillaries
- veins:
- changes little during the cardiac cycle
- small pressure gradient, about 15 mmHg
71
factors aiding venous return
- 1. respiratory pump- pressure changes created during breathing
- 2. muscular pump- contraction of skeletal muscles "milk" blood toward the heart and valves prevent backflow
- 3. vasoconstriction- vasoconstriction of veins under sympathetic control
72
inotrope
-force of contraction
73
maintaining blood pressure
- the main factors influencing blood pressure:
- cardiac output (CO)
- peripheral resistance (PR)
- blood volume
- important and vital to bring blood to organs
74
cardiac output (CO)
- determined by venous return and neural and hormonal controls
- resting heart rate is maintained by the PNS
- stroke volume is controlled by venous return (EDV)
- during stress, the cardioaccelerator center increases heart rate and stroke volume via sympathetic stimulation -> ESV decreases and MAP increases
75
of the following cardiovascular components, which contains the majority of the bodys blood volume at any one time
- pulmonary capillaries
- heart
- systemic veins and venules*
- systemic capillaries
76
of the following blood vessels components, which is the most critical in regulating systemic blood pressure
- tunica intima
- tunica media
- tunica externa*
- venous valves
77
what is the major factor controlling stroke volume during resting periods
- sympathetic input
- parasympathetic input
- venous return to the heart*
- peripheral resistance changes
78
control of blood pressure
- F=change pressure/resistance
- short term neural and hormonal controls -> counteract fluctuations in blood pressure by altering peripheral resistance
- long term renal regulation (kidneys) -> counteract fluctuations in blood pressure by altering blood volume
79
short term BP control mechanisms: neural controls
neural controls operate via reflex arcs that involve:
- baroreceptors- mechanoreceptors (stretch and chemoreceptors (chemicals)
- vasomotor centers- located in medulla- maintains vasomotor tone (moderate constriction of arterioles
- vascular smooth muscle
80
short term mechanisms: baroreceptors-initiated reflexes
- increased blood pressure stimulates baroreceptors to increase input to the vasomotor center
- inhibits the vasomotor center, causing arteriole dilation and venodilation
- stimulates the cardioinhibitory center
- used as an emergency brake to avoid abnormally high BP
- baroreceptors in carotid sinus protect blood supply to brain
- elderly often have blunted baroreceptors- can cause lightheadedness on sit to stand
81
short term mechanisms: chemoreceptor-initiated reflexes
- chemoreceptors respond to rise in CO2 drop in pH or O2
- increase blood pressure via the vasomotor center and the cardioacceleratory center
- are more important in the regulation of respiratory rate
- located in carotid sinus and aortic arch
82
influence of higher brain centers
- impulses from cerebrum pass through CV centers in medulla
- variations in emotional state may affect CV responses (fight/flight):
- anticipatory HR
- white coat phenomena
- voluntary control over HR/HP through biofeedback/meditation
83
hormonal controls
- short term regulation through changes in peripheral resistance
- long term regulation through changes in blood volume
84
short term mechanisms- hormonal controls
1. adrenal medulla hormones (NE, E)
2. angiotensin 2- generated by kidney release of renin, causes vasoconstriction
3. atrial natriuretic peptide (ANP) from atria in heart, causes vasodilation
4. ADH (hypothalamus)- intense vasoconstriction when BP falls dangerously low
85
long term mechanisms- renal regulation
- kidneys act directly and indirectly to regulate arterial blood pressure by altering blood volume
- 1. direct renal mechanism (at kidney)
- 2. indirect renal (renin-angiotensin) mechanism
86
direct renal mechanism (kidney)
- alters blood volume independently of hormones
- increased BP or blood volume causes the kidneys to eliminate more urine, thus reducing BP (rate of which blood filters through kidney tubules speeds up, faster filtrate flow and kidneys cannot reabsorb fast enough)
- decreased BP or blood volume causes the kidneys to conserve water, and BP rises
87
indirect mechanism
- the renin-angiotensin mechanism -> decrease arterial BP -> release of renin -> renin -> production of angiotensin 2
- angiotensin 2:
- 1. adrenals secrete aldosterone which enhances renal absorption of Na
- 2. causes posterior pituitary to release ADH
- 3. triggers sensation of thirst
- 4. causes vasoconstriction which increases blood pressure by increasing resistance
- kidneys release renin
88
hypotension
- low blood pressure
- systolic pressure below 100mmHg
- often associated with long life and lack of cardiovascular illness
89
hypertension
- high BP
- sustained elevated arterial pressure of 140/90 or higher
- may be transient adaptations during fever, physical exertion and emotional upset
- often persistent in obese people
90
hypovolemic shock
-results from large scale blood loss
91
vascular shock
- results from extreme vasodilation and decreased peripheral resistance
- anaphylaxis
92
cardiogenic shock
- results when an inefficient heart cannot sustain adequate circulation
- pump failure
93
transient vascular shock
-prolonged exposure to heat, sun stroke
94
velocity of blood flow
- changes as it travels through the systemic circulation
- is fastest in the aorta, slowest in the capillaries, increases again in veins
- slow capillary flow allows adequate time for exchange between blood and tissues
95
autoregulation of blood flow (intrinsic)
- local regulation of blood flow, controlled intrinsically by changing diameter
- metabolic- stimulated by shortage of O2 or inflammatory chemicals
- myogenic- involves the local response of smooth muscle to passive stretch:
- 1. passive stretch involves vasoconstriction
- 2. reduced stretch promotes vasodilation
96
long term autoregulation: angiogenesis
- occurs when short term autoregulation cannot meet tissue nutrient requirements
- the number of vessels to a region increases and existing vessels enlarge
- common in the heart when a coronary vessel is occluded, or throughout the body in people in high altitude areas
97
blood flow: skeletal muscles
- during muscle activity blood flow increases in direct proportion to the metabolic activity
- during muscle activity local controls override sympathetic vasoconstriction
- muscle blood flow can increase 10x or more during physical activity
98
blood flow and exercise
- major portion to working muscles
- shunting of blood: kidneys practically shut down
- blood flow is not disturbed- brain and heart
99
blood flow in brain
- blood flow to the brain is constant, as neurons are intolerant of ischemia
- metabolic controls- declines in pH and increased CO2 cause marked vasodilation
- myogenic controls- decreases in MAP causes cerebral vessels to dilate vice versa
- increase in CO2 causes vasodilation
- decrease in CO2 (hyperventilation) causes vasoconstriction
100
the brain is vulnerable under extreme systemic pressure changes
- MAP below 60mmHg can cause syncope (fainting)
- MAP above 160 can result in cerebral edema
- increases capillary permeability
101
blood flow: lungs
- autoregulatory mechanism is opposite of that in most tissues
- low O2 levels cause vasoconstriction
- high levels of O2 promote vasodilation
- allows for proper O2 loading in the lungs
102
blood flow: heart
- during ventricular systole:
- coronary vessels are compressed
- myocardial blood flow ceases
- stored myoglobin supplies sufficient oxygen
103
heart during strenuous exercise
- coronary vessels dilate in response to local accumulation of vasodilators
- blood flow may increase 3 to 4 times
104
circulatory pathways
- 2 main circulations:
- pulmonary circulation- short loop that runs from the heart to the lungs and back to the heart
- systemic circulation- long loop to all parts of the body and back to the heart
105
arteries
- delivery- blood pumped into single systemic artery- the aorta
- location- deep, protected by tissues
- pathways- fairly distinct
- supply/drainage- predictable supply
106
veins
- delivery- blood returns via superior and interior venae cavae and the coronary sinus
- location- both deep and superficial
- pathways- numerous interconnections
- supply/drainage- usually similar to arteries, except dural sinuses and hepatic portal circulation
107
diastole vs systole
heart is in diastole slight longer
108
abdominal aortic aneurysm
- dilation of artery wall
- male, smokers over 65
- often no symptoms
- pulsation near navel
- can rupture and cause immediate death
- dx. US
- surgery if > 5.5 cm
