Pathophys quiz 2 CV Flashcards
Pressure
Force exerted; measured in mmHg
Flow
Volume moved; measured in mL/min (volume moved in the time)
Resistance
how difficult it is for the blood to flow between 2 points at any given pressure difference; the measure of the friction that impedes flow
3 things that contribute to resistance?
- Blood viscosity
- Total blood vessel length (surface area increases resistance)
- Blood vessel diameter (This is the biggest contributor to min-to-min control of resistance in the vascular system)
what has the biggest effect on resistance?
Radius
Flow =
change in pressure/ resistance
In a system with constant pressure if you increase resistance you _____ flow and if you decrease resistance you _______ flow
decrease, increase
In a system with constant pressure if you increase pressure it _____ flow
increases
In a system with constant pressure if you decrease pressure you ____ flow
decrease
In a system with constant pressure F and R are _______ related
inversely
Positive chronotropic factors ______ HR
increase
negative chronotropic factors ______ HR
decrease
3 systems that regulate the heart
Endocrine system, nervous system, kidney
How does the endocrine system regulate the heart?
Atrial Natriuretic peptide (hearts own endocrine system
Atrial Natriuretic peptide
- secreted by specialized cells in the atria
- Regulates the concentration of Na+ in extracellular fluid
How does the Nervous system regulate the heart?
(body talks to the heart through this system)
Sympathetic nervous system (SNS)
Parasympathetic nervous system (PNS)
How does SNS regulate the heart?
- Increases HR / Increases Stroke volume
- Innervates entire heart muscle and node cells
- Binds the neuroendocrine hormone epinephrine from the adrenal gland
- Beta-adrenergic receptors on the SA node and on Pumping cells
SNS releases ______ through thoracic spinal nerves which kicks in first!
Norepinephrine (NE)
_______ hormone from the adrenal medulla will kick in second
Epinephrine
How does the PNS regulate the heart?
- Slow HR
- innervates just the SA/AV nodes
- Muscarinic Cholinergic receptors on the SA node only
- releases Acetylcholine (hormone) through vagus nerve
How do the Kidneys regulate the heart?
Control blood volume by retaining or relating fluid (affects stroke volume (SV)
arteries and veins both contain what 3 structures, but vary in the amounts of each?
smooth muscle
endothelial cells
fibroblasts
Structures involved in the vascular system?
- Arteries
- Elastiuc arteries (conduit), muscular arteries, arterioles - Capillaries
- veins
- venules
Arteries need to be more elastic, while veins are more _____
compliant
Arteries are responsible for transmitting _____ to the vessels beyond them.
pressure
they are pressure reservoirs bc of their elastic recoil
Veins: the higher the compliance, the more they can _____ without corresponding increase in pressure
stretch out
Compliance =
change in volume / change in pressure
Veins have _____ walls and _____ compliance
thin, high
Pulmonary pressure is always ____ than arterial pressure
lower
Pressure ______ the farther it travels down the systemic circuit
decreases
does pressure increase or decrease between the arterioles and capillaries?
decreases greatly
what controls min - to - min blood flow into the capillaries?
muscular is or arterioles
what do veins have to prevent back flow?
valves
Respiratory pump
pressure changes in the central cavity due to the negative pressure generated due to breathing. this helps pull blood back to the heart
muscle pump
when muscles contract they squeeze the veins, which moves blood forward. valves prevent back flow. the smooth muscle in the veins is under SNS control and contracts when stimulated, similar to arterial smooth muscle.
What are the components of the cardiac cycle? (slide 38)
Isovolumetric contraction, ventricular ejection, isovolumetric relaxation, ventricular filling
Isovolumetric contraction
the ventricle starts contracting, but no valves are open at first because the pressure hasn’t gotten high enough to open them
ventricular ejection
ventricular pressure gets high enough to causesemilunar valves to open. when the LV pressure is higher than aortic pressure, the valve opens and the aorta fills
Isovolumetric relaxation
the ventricle relaxes, causing the semilunar valves to fall shut. the aortic pressures do high theres a backwards slosh of aortic blood against the aortic valve, creating the dicrotic notch (the blood that sloshes back exits through the coronary Ostia to oxygenate the blood
Ventricular filling
the atria are contracting, the ventricles are relaxed. AV valves are open bc atrial pressure is at least equal to ventricular pressure
Heart sounds
systole, diastole
Systole sounds:
closing of the mitral and tricuspid valves (LUB)
diastole sounds:
Closing of the pulmonary and aortic valves (DUB)
Why is diastole longer than systole?
bc ventricles which are bigger are filling
valve problems
stenotic (narrow valve) - turbulent flow insufficient valve (leaky valve) - turbulent backflow
What causes a murmur
turbulent flow or back flow
systolic pressure =
maximum pressure at systole
diastolic pressure =
minimum pressure at diastole
pulse pressure=
systolic- diastolic
Mean arterial pressure (MAP) =
diastolic + 1/3 of the pulse pressure
What is cardiac output?
amount of blood pumped out of each ventricle in one minute
Cardiac Output =
HR x SV
Stroke Volume (SV) =
EDV - ESV
(fairly constant in a healthy system)
the amount of blood that was pumped out of the heart after contraction
End diastolic volume (EDV)
total amount of blood in the ventricle that has the potential to be pumped out
End systolic volume (ESV)
the amount of blood left over in the ventricle after the contraction of the heart
amount how much blood does the heart pump out during each beat?
60%
When SV decrease, the body will increase what to compensate in an unhealthy system?
HR
Inotropy
positive or negative things that affect contractility
SV can be increased by what?
emptying the ventricles better (increasing ventricular contraction)
-SNS stimulation increases SV
What is the most common way of changing CO?
HR
Chronotropy
positive (increases HR) or negative (decreases Hr) that affect HR
(HR can also be controlled by the nervous system)
Frank-starling Law
- the critical factor controlling stroke volume is preload
- Length/tension relationship (overextension leads to inefficient pumping and under extension limits force)
- Afterload
Preload
the degree to which the cardiac muscle cells are stretched (amount of blood in the ventricles) before the contract
Amount of blood in the ventricles is controlled by what 2 factors?
venous return and the amount of time between ventricular contractions
Anything that increases venous return or slows HR _______ the EDV
increases
ex. increased SV = Increased EDV
Afterload
pressure that the ventricles must overcome to force open the aortic and pulmonary valves
-anything that increases systemic or pulmonary arterial pressure can increase afterload (hypertension)
it is easiest for the heart to work with a ____ preload and ____ afterload
high
low
Ejection fraction =
SV / EDV (measures contractility)
- expressed as a percentage (normally between 50-70)
- increased contractility = increased ejection fraction
What does the SNS innervate?
SA/AV node and individual cardiac cells by releasing Norepinephrine (NE). It also binds the neuroendocrine hormone epinephrine from the adrenal gland
PNS innervates what?
only the SA/AV node and releases Acetylcholine
What is BP role in homeostasis of oxygen delivery?
By using sympathetic and parasympathetic stimulation to innervate and suppress the vessels in order to vasodilator and constrict depending on the body need for CO2
What is pH role in homeostasis of oxygen delivery?
by using ion channels to facilitate the movement of CO2 and O2 to alter pH within a cell. increased acidity (aka increased CO2) increases oxygen drop off
What is Oxygens role in homeostasis of oxygen delivery?
Hypoxic state= increased HR
What is ions role in homeostasis of oxygen delivery?
some atria cells secrete atrial natriuretic peptide which regulates Na+
what two things keep valves from flying open?
Chordae tendinae and Papillary muscles
what valves are open during diastole?
M/T
What valves are open during systole?
P/A
Hydrostatic pressure:
pressure needed for water to be forced out of the capillaries (filtration)
-over comes osmotic pressure at the beginning of the capillaries
Osmotic (oncotic) pressure
pressure causes O2 to flow into the capillary
- it opposes hydrostatic pressure, keeping fluid in the cells.
- Over comes hydrostatic pressure at the end of capillaries
arrhythmia
uncoordinated atrial and ventricular contractions caused by a defect in the conduction system
defibrillation
application of an electrical stimulation to shock the heart back into normal SA rhythm
Heart block
damage to AV node
Total heart block
ventricles beat at their intrinsic rate (purkinje fiber rate) = too slow to maintain circulation
partial heart block
AV node impulse is slowed but it does get through (pacemaker treats this)
Pacemaker
substitues SA and/or AV nodes. for chronic issues. can be single or double lead
extrasystoles
premature contractions (atrial or ventricular) -Ventricular (PVC) most problematic
Extopic focus
abnormal pacemaker that takes over the conducting system
-can go faster than SA node when it takes over for the damaged SA node
Fibrillation
rapid and irregular (usually out of phase) contraction where the SA node is no longer controlling HR
Atrial Fibrillation can cause what 2 things?
clotting and inefficient filling of the ventricles
Ventricular Fibrillation
- life threatening
- ventricles pump inefficiently and without filling
What does the pulmonary system do?
carries oxygen poop blood to the lungs and then back to the heart
why is pressure in the pulmonary pump less?
blood is going to 1 organ at a shorter distance and the capillaries in the lungs are fragile and damage easily
What does the systemic system do?
carries blood from the heart to the rest of the body
why is pressure in the systemic system higher?
bloody has to be sent out a further distance to the entire body
4 advantages to having a closed system with 2 parallel loops
- more bang for you buck (stronger contractions)
- easy to create force when pushing against each other (shared wall, atrioventricular septum)
- Lungs are close by
- More efficient, blood is being oxygenated and delivered to the rest of the body simultaneously
Disadvantages to having a closed system with 2 parallel loops
A small imbalance in one side affects the other side
- if the right side doesn’t deliver/fill properly, the left side has nothing to pump out (atrial dysfunction)
- if the left side doesn’t pump fast enough, it backs up into the right (systolic dysfunction)
Describe portal systems
- 2 systems that have 2 sets of capillaries that exchange with their surroundings, found chained together in one-two fashion
- ensure all parts of the organ receive what they need
- 2 drop-off points
Hepatic portal system
vein-capillary-vein
-directs blood from parts of the GI tract to the liver. substances absorbed in the small intestine travel first to the liver for processing before continuing to the heart
Hypothalamic portal system
vein-capillary-vein
- picks up hormones at the hypothalamus and drops them off in high concentration at the pituitary
- not a lot of releasing hormone is needed because it is not being diluted by the entire blood stream
Nephron portal system
artery-capillary-artery
-water is filtered out at one capillary bed, reabsorbed at another
order of blood through the body
arteries-arterioles-capillaries-venules-veins-heart
arteries =
away (normally oxygenated)
arterioles =
smallest arteries. their fx in controlled by neural, hormonal, and local chemicals (see study guide for more info)
autoregulation
dynamic process of constant changing diameter in the arterioles
paracrine signaling:
endothelial cells secrete paracrine agents (affect smooth muscle) and induce a relaxation or contraction
NO is one of the most important paracrine signals because…
its causes vasodilation for proper vessel tone.
-sns / pos make arterioles more sensitive to NO
Continuous capillaries are…
most common and allow passage of fluids and small solutes (skin and muscle)
fenestrated capillaries
more permeable to fluids and solutes than continuous capillaries- allowing for more rapid transfer of substances into/out of the capillary (kidneys, intestines, endocrine (hormone) tissue)
Sinusoidal capillaries
leaky capillaries that allow large molecules to pass between blood and surrounding tissues (liver, bone marrow, lymphatics)
Filtration
flow of fluid leaving the plasma to the interstitial fluid through the capillaries
absorption
flow of fluid from the interstitial fluid to the plasma through the capillaries
Colloid osmotic (oncotic) pressure remains _______through the entire capillary
constant
Hydrostatic pressure is _____ at the arteriole end of the capillary and _____ at the venous end of the capillary
Higher, lower
3 layers of the veins:
Tunics: interna-media-externa (less smooth muscle and elastin than arteries
varicose veins are caused by what
leaky valves
4 determinants of venous pressure
- Nervous sytem (sympathetic increases BP by increasing central blood volume)\
- Skeletal muscle “pump” of the legs
- Inspiratory effort (creates negative pressure in the thorax)
- blood volume (more volume = higher pressure)
Pulmonary artery
carries deoxygenated blood to the lungs
pulmonary vein
carries oxygenated blood to the heart
umbilical artery
carries deoxygenated blood away from the fetus to the mom
how much blood is in our veins at any given time?
60%
how many more veins do we have than arteries?
3x as many
Why are arteries stiffer?
accommodate larger volumes of blood and pressure
what percent of your capillaries are open at any given time?
5-10%
What would happen if all of your capillaries were open at the same time?
BP drops, not enough blood goes back to your heart, and SHOCK
Hematocrit
Percentage of blood made up by RBC
- 45% men
- 38-42% women
- measured by separating components of blood via centrifuge
3 layers of the heart
Epicardium, myocardium, endocardium
epicardium
superficial outer layer of the heart
Myocardium
- bulk
- cardiac muscle
- middle layer
endocardium
inner layer
- made of endothelium resting on a thin layer of connective tissue
- continuous with lining of blood vessels (this is important bc it reduces “roadblocks”, less resistance)
Progression of blood through circulatory system
- Superior and inferior venacava
- Right atrium
- Tricuspid valve (right atrioventricular)
- Right ventricle
- Pulmonary valve(semilunar)
- pulmonary artery
- lungs
- pulmonary vein
- Left atria
- Bicuspid (mitral) (left atrioventricular) valve
- Left ventricle
- Aortic valve (semilunar)
- Aorta
- Systemic
Where does the pause occur during conduction of the heart and why does it occur?
- Occurs at the bundle of His
- allows for atria emptying and ventricle filling
What are the 2 reasons why the refractory period is needed?
- allows for ventricular emptying
- prevents cardiac tetani
- T wave= ventricular reporlarization
how does the percentage of blood change in the brain, heart, skeletal muscle, skin, kidneys, abdominal organs, and other from resting to exercise?
Brain: less Heart: same Skeletal muscle: more Skin: more Kidneys: less abdominal organs: less Other: less
