Cardio- Nicely Flashcards
4 layers of the heart
Pericardium- loose-fitting sac that surrounds the heart
Epicardium is the outer layer of the heart (visceral layer)
Myocardium is the muscle layer
Endocardium lines the chambers of the heart (smoother layer)
positioning of the heart in the chest- right side is more ____ while left is more _____
oblique position: right is more anterior and left is more posterior
Myocardium beats as one unit due to ________ in cardiac muscle that allow for easy passage of _______ and _____
Contains ____and ____ (like skeletal muscles)
low-resistance gap junctions
ions and electrical impulses
actin and myosin
cardiac muscle action is regulated by what proteins? what are the three subtypes? what do they do?
troponin, troponin myosin complex
types: T, I, and C
- regulate calcium- mediated muscle contraction
______ can be measured during muscle injury to diagnose myocardial infarction
troponin T and I
what are the three layers that all vessels (besides capillaries) possess? what is the purpose of each?
- Tunica externa or tunica adventitia: (outermost layer);collagen fibers ; Protect and anchor the vessels
- Tunica media- middle: Smooth muscle; Allows constriction of vessels
- Tunica intima:
Single layer of flattened endothelial cells with minimal underlying connective tissue
–>Provides slippery surface to prevent platelet adhesion and blood clots
which vessel type has Highest blood volume resistance AND
Extensive smooth muscle that is tonic (constantly contracted)?
arterioles
what are the main properties of capillaries pertinent to their function?
- Single layer endothelial cells surrounded by basal lamina
- Exchange of gas, nutrients, water, solutes, waste
- Low velocity allows for increased time for exchange
- selective perfusion based on metabolic demand (fight or flight, rest/digest) - shutting down or opening more where needed
how do lipid-soluble vs water-soluble substances move in and out of capillaries?
Lipid-soluble substance – dissolve in endothelial cell membranes and diffusing across
Water-soluble substance – through water-filled cleft between endothelial cells or large pores in walls (fenestrations)
what are splanchnic arterioles?
arterioles that feed gut/GI system
A1 vs B2 on the vascular system?
A1- excitatory = vasoconstrict
B2- inhibit = vasodilate
(do so by opening (excite) or closing (inhibit) Ca channels in smooth muscle)
AV valves are _____ unless diseased
one way!
systemic circulation path
Left heart Systemic Arteries (Arterioles) Systemic Capillaries – greatest surface area (Venules) Systemic Veins
pulmonary circulation path
Right heart
Pulmonary Arteries
Pulmonary Capillaries
Pulmonary Veins
what is stroke volume?
Volume ejected by ventricle with each heart beat
SV = (End-diastolic volume) – (End-systolic volume)
what is ejection fraction?
Fraction of end-diastolic volume ejected in each stroke volume
Measuring efficiency of ventricular contraction
Normal = ~55%
EF= SV/End-diastolic volume
what is cardiac output?
Total volume of ventricular ejection over a unit of time
CO = SV x HR (bpm)
end-diastolic volume can be thought of as synonymous with …?
preload
what is the frank-starling relationship?
venous return = cardiac output (in a normal heart) - aka more stretch/ volume = more output = more venous return (cycle)
positive vs negative ionotrope effect
agents that alter muscle contraction force:
Positive inotropes - increases contractility
-Increases SV and CO
-Increases EF
Negative inotropes – decreases contractility
-Decreases SV and CO
- Decreases EF
Percentage of Cardiac output flow to different areas increases or decreases based on_____
O2 demands
what are the different percentages of CO to different parts of the body?
Cerebral 15% Coronary 5% Renal 25% GI 25% Skeletal Muscle 25% Skin 5%
what are CO distribution alterations? 3 types…
- CO constant but redistribution of flow
-Selective arteriolar pressure resistance
=Change flow to one organ at expense of others - CO increases or decreases but distribution of flow is constant
- combo of 1 and 2
how does venous size effect blood flow velocity?
an inverse relationship between velocity and cross sectional area of a vessel.
skinnier vessel = more pressure on it (higher velocity), larger diameter = less pressure on it (b/c more surface area)
what is the principle of the poisuielle equation?
Blood flow depends on resistance, vessel diameter, blood viscosity
Higher viscosity = higher resistance
Longer vessel = higher resistance
Bigger radius = lower resistance by 16 fold!! (4th power)
resistance is affected by vessel arrangement… series vs parallel
series: Total resistance = sum of individual resistances in the circuit because total flow is the same
parallel: Total resistance = less than any individual resistances b/c it is expressed as a fraction
1/Rtotal = 1/R1 + 1/R2 + 1/R3 + ….
Increasing resistance in the circuit = decreased total resistance
what is laminar flow?
what is normal —>smooth vessel- less resistance in the center of the vessel so that flows faster
what is turbulent flow?
what results from laminar flow being disrupted by valvular irregularity or clot (hear murmur or bruit)
what is “shear” in terms of flow through the vessels?
the resistance of flowing blood on the sides vs the center of the vessel:
-Highest at the wall of a vessel because the greatest difference in velocity is between the motionless layer at the vessel wall and the moving layer of blood next to it
(Breaks up plaques and decreases viscosity)
-Lowest in center of vessel = velocity highest
which vessels would have the lowest compliance?
Aged arteries : requires the arteries to operate under higher pressure to contain an appropriate amount of volume
(Stenosed/sclerosed)
diastolic pressure
lowest arterial pressure
Ventricular relaxation
systolic pressure
highest arterial pressure
Systolic ejection
dicrotic notch in curve
Dicrotic notch in curve – slight backward flow of blood with closure of aortic valve
pulse pressure
Systolic pressure minus diastolic pressure
-Pulse pressure diminishes as blood moves from large arteries to absence in the capillaries and beyond (due to increased resistance in arterioles and increased compliance in veins)
Pressures within the system have to _____ in order to _____
differ in order to drive flow
Equal pressures throughout would not create this driving force.
formula for mean arterial pressure (MAP)
MAP = diastolic + 1/3 pulse pressure
when is MAP highest and lowest?
Mean pressure is highest in aorta and decreases throughout the system to being the lowest in the veins
what is the mean aortic pressure?
100mmHg
Minimal energy is lost as blood flows from aorta to large arteries due to ______
arterial elastic recoil - so the pressure remains high
RV wall is ____ than LV wall due to ______ pressure work on R
thinner, decreased
pulmonary vs systemic resistance
Pulmonary resistance is lower than systemic resistance to achieve the same amount of flow
CO of RV = CO of LV
3 types of pathology that can alter compliance of vessels?
ateriosclerosis, aortic stenosis, aortic regurg.
what are the effects of arteriosclerosis?
Plaque decreases diameter
Decreased compliance
Increased SBP, PP, and MAP
effects of aortic stenosis? what will you hear?
Narrowed valve (hardened) (systolic murmur)
Decreased SV
Decreased SBP, PP, MAP
Increase myocardial O2 consumption because it requires increased work of the ventricular muscle to eject against an increased aortic pressure (afterload)
effects of aortic regurg? what will you hear?
Incompetent valve : backflow into relaxed, low pressure left ventricle (diastolic murmur)
arteriosclerosis vs atherosclerosis
Arteriosclerosis is the stiffening or hardening of the artery walls. Atherosclerosis is the narrowing of the artery because of plaque build-up. Atherosclerosis is a specific type of arteriosclerosis
three traditional risk factors of atherosclerosis?
- high cholesterol
- constitutional (older, male, FH)
- lifestyle
4 non-traditional risk factors for atherosclerosis?
- C-reactive protein (CRP): (marker of systemic inflammation- from infection or trauma)
- serum homocysteine: (from animal protein)
- lipoprotein (a): hereditary increased cholesterol delivery
- infectious agents (chlamydia, herpes, CMV)
what are fatty streaks?
Thin yellow lines of cholesterol and macrophages in major arteries
Does not cause symptoms but can advance over time (into atherosclerosis) …
what is a fibrous atheromatous plaque?
decrease radius = decrease bloodflow = possible clot
progression of…
-Accumulation of intra- and extra-cellular lipids
-Proliferation of vascular smooth muscle cells
-Formation of scar tissue
-Calcification
what are foam cells?
first piece of fatty streak
4 steps of plaque formation
- endothelial cell injury
- migration of inflamm cells
- lipid accumulation and smooth muscle cell proliferation
- plaque structure formation
what happens in endothelial cell injury?
monocytes and platelets adhere to site
what do monocytes do in the phase of “migration of inflammation cells” ?
migrate to intima and transform into macrophages, engulfing lipoproteins (mainly LDL)
in what step of plaque formation are foam cells formed?
“lipid accumulation and smooth muscle cell proliferation”
Activated macrophages release toxins that oxidize LDL that is aggressively ingested by macrophages forming foam cells
in plaque structure formation, there is aggregation of …
Smooth muscle cells, macrophages, leukocytes
Extracellular matrix (collagen and elastic fibers)
Intracellular and extracellular lipids
what is the cardiac (CO) function curve?
CO vs RA pressure (direct relationship)
Incr. venous return increases right atrium pressure –> increased end-diastolic volume & increased ventricular fiber length –> increases CO
a max venous return can be reciprocated by CO (~4 mm Hg of right atrium pressure) – curve levels off
what is the vascular function curve?
- Venous Return vs RA pressure (indirect relationship)
- Venous return from pressure gradient
- Lower atrial pressure = incr. venous return
- Decreased TPR (resistance in arterioles) = increased venous return
- slope depends on TPR
redistribution of blood: dec. venous compliance = _____ stressed volume?
-Decreased venous compliance (venoconstriction) = increased stressed volume (backs up into arteries)
(and vice versa)
how would you calculate arterial pressure?
Pa = CO * TPR
what two systems regulate arterial pressure?
RAAS (changes blood volume) and Baroreceptor reflex (restores set point)
what does the intersection of the cardiac function curve and vascular function curve represent?
the set point (Steady state) for the system at the time of measurement (may be lower or higher than normal if change in CO or TPR
the baroreceptor reflex is mediated by _____ while the RAAS is mediated by _____
neural mediated - fast
hormonally mediated- slow
how does the baroreceptor reflex work?
mechanical stretch pressure receptors in carotid sinus and aortic arch
Send impulses via afferent neurons to CV vasomotor centers in brainstem with communication back to the heart and vessels through efferent neurons
baroreceptor reflex: larger stimulus = ?
rapid change in pressure
baroreceptor reflex in carotid sinus vs aortic arch?
carotid sinus (bifurcation of internal and external): respond to inc. or dec. in arterial pressure aortic: respond to inc. in arterial pressure
sympathetic vs parasympathetic response from baroreceptor reflex: what do the responses from each pathway do? (affect on SA node, cardiac muscle, arterioles, venous system)
- Parasympathetic response
Vagus nerve communicates to SA node to decrease HR - Sympathetic response
Affects SA node: Incr. HR
Affects cardiac muscle: Incr. contractility and SV
Affects arterioles: Incr. vasoconstriction and TPR
Affects venous system: Venoconstriction = decr. unstressed volume
what happens to the baroreceptor reflex in someone with chronic HTN?
receptor does not response to pressure. From inc. set point of BP on brain stem or dec. baroreceptor sensitivity
what happens to the baroreceptor reflex with a hemorrhage?
Decr. BV = decr. stressed vol (on arterial side)
Decr. Arterial Pressure activates reflex
=Decr. firing rate of carotid sinus nerve
=inc. symathetic activity
what is the valsalva maneuver and what is the pathophys behind it?
when you bare down (like you’re going to poop)
Increased intrathoracic pressure = decreased venous return= decreased CO and arterial pressure
Intact reflex causes:
-Increased sympathetic activity
At completion of maneuver: Rebound increase in venous return, CO, and arterial pressure sensed by baroreceptor that causes a decrease in HR
dec. arterial pressure activates RAAS.. then
______ is converted to renin
prorenin
renin can be decreased by ____ antagonist
B1
how does angiotensin increase ECF volume, BV and BP?
Stimulates Na+-H+ exchange =reabs. of Na+ and HCO3- in kidney
1. Increased thirst (hypothalamus)
2. secretion of ADH
3. Increased water reabs. in kidney
All three = inc. ECF volume, blood volume, and BP
Directly works to vasoconstrict arterioles
Increased TPR = Increased MAP
what does angiotensin II stimulate secretion of?
aldosterone–> increases NaCl and H2O reabsorption
Increases ECF volume/blood volume
what do chemoreceptors in the carotid and aortic bodies do?
Respond to decreased O2 in blood, especially when accompanied by increased CO2 and/or decreased pH
= arteriolar vasoconstriction in skeletal muscle, renal, and splanchnic vessels
what is the goal of chemoreceptor response ?
- blood being sent from where its not needed to most important areas where it is needed (brain and heart)
what do chemoreceptors in the medulla do?
Sensitive to CO2 and pH (decreased cerebral blood flow = increased CO2 and decreased pH) Increases sympathetic outflow Increased TPR Dramatic increase in Arterial Pressure Example: Cushing reaction
what is the cushing reaction? what is the triad?
a response to incr ICP - leads to brain herniation and death
HTN, irregular breathing, bradycardia
where does ADH come from and when is it stimulated?
Posterior pituitary hormone
Secretion stimulated by
Increased serum osmolarity
Decreased blood volume and BP
what are the receptors for ADH?
V1: Vascular smooth muscle
Vasoconstrict arterioles – increases TPR
V2: Renal collecting ducts
Water reabsorption to maintain body osmolarity
where are low pressure baroreceptors located and what do they do in response to volume changes?
veins, atria and pulmonary arteries
sense inc. BV, will try to counteract by……
-secrete ANP from atria b/c of increased pressure
-dec. ADH by hypothalamus
-renal vasoD
-inc. HR (bainbridge reflex)
ANP (atrial nateuritic peptide) does what?
inc vasoD and dec. TPR … in kidney leads to increased Na+ and H2O excretion to decrease BV
ADH is made in the ____ and stored in the _____
hypothalamus, pituitary gland
decrease ADH = ____
decreased reabs. of H2O
renal vasodilation = ____
increased Na+ and H2O excretion
what is the bainbridge reflex?
also called the atrial reflex, is an increase in HR and CO due to an increase in central venous pressure. –> incr. renal perfusion = inc. Na+ and H2O excretion
-Increased BV is detected by low pressure stretch receptors in atria
rate of diffusion in microcirculation depends on …
in capillaries….driving force and available surface area
microcirculation lipid soluble vs water soluble?
Lipid soluble: O2 and CO2
Diffuse through endothelial cells
Water soluble: Water, ions, glucose, amino acids
Diffuse between endothelial cells
So, the surface area available for diffusion is less than that for lipid soluble gases
what is the most important property for fluid exchange across capillary walls? what is it driven by?
osmosis … driven by starling pressures
what are the starling pressures?
Hydrostatic pressure (water movement) Osmotic/oncotic pressure (diffusion of H2O driven by conc gradient: proteins that can't cross change pressures by pulling fluid in)
what is the starling equation?
Fluid movement across a capillary wall is dependent on the net pressure (the sum of hydrostatic and oncotic pressures)
Movement out of the capillary is termed filtration
Movement into the capillary from the interstitium is absorption
what is hydraulic conductance?
Hydraulic conductance (capillary water permeability) determines the amount of fluid that is allowed to move across the membrane at a given difference in pressures
how can hydraulic conductance differ/change?
- Differs in different areas of the body
- Not influenced by arteriolar resistance, hypoxia, or increased metabolites
- Capillary injury will increase hydraulic conductance and allow for loss of proteins from within the circulation
capillary hydrostatic pressure ____ filtration? affected by …
filtration
-affected more so by changes in venous pressure than by arterial pressure
interstitial hydrostatic pressure and capillary oncotic pressure ____ filtration?
oppose
increased capillary proteins ____ filtration
decreases
interstitial oncotic pressure _____ filtration. affected by …
favors
-affected by proteins in interstitium
edema occurs when…
when filtration out of capillaries into the interstitium is greater than the ability of the lymphatics to remove this fluid and return it to circulation
(or w/ impairment of lymphatic drainage)
_____valves allow movement of interstitial fluid and proteins ____ but not ____ of the lymphatics
one-way flap
in but not out
where to lymphs empty into?
large veins
systemic HTN leads to ….
Decreased venous compliance (unstressed volume) causing blood to back up into the arteries (stressed volume)
Increase LV work due to higher pressures
Leads to LV wall hypertrophy
S&S of CHF?
Symptoms
Dyspnea, orthopnea, fatigue, weakness, edema, weight gain
Signs
Tachypnea, tachycardia, JVD, edema, cyanosis, ascites
how does CHF often start and what is the pathophys behind S&S?
left heart failure —> fluid back up into the pulmonary vascular (lungs) b/c it comes from left ventricle =SOB, cyanosis, etc.
—> then it keeps backing up into the system —> leg edema, JVD, etc —> right ventricular failure
you can start RVfailure but more often LVfailure leads to RVfailure
what two systems are activated by CHF?
RAAS and Baroreceptor
(from decreased MAP - more BV on venous side)
how does RAAS activation exacerbate edema?
Angiotensin II leads to peripheral vasoconstriction
Aldosterone increases Na reabsorption, total body Na, and ECF volume – exacerbating the edema
txt for CHF?
Administer a positive inotrope to increase contractility
Administer diuretic and restrict Na intake (b/c body is holding onto sodium)
monitoring CVP (central venous pressure) goals
Goal CVP = 8-12 mm Hg
CVP < 5 mm Hg = hypovolemia
CVP > 18 mm Hg = hypervolemia/volume overload
three methods for monitoring pressure
CVP (central venous pressure), (PCWP) pulmonary capillary wedge pressure and TTE (Transthoracic Echocardio)
*TTE is gold standard
what can TTE measure?
Pulmonary artery pressure
Cardiac function
Cardiac output
