Exam 2 Flashcards
Purposes of the cardiovascular system
Transport O2 to tissues & removal of waste
Transport of nutrients to tissues
Regulation of body temperature
Circulatory System includes
Heart
Arteries & arterioles
Capillaries
Veins & venules
Arteries & arterioles
Carry blood away from heart
Heart
Pumps blood
Capillaries
Exchange site for nutrients & waste products between tissues & circulation
Veins & venules
Carry blood toward heart
Composition of Blood:
Composed of liquid plasma & formed elements
Erythrocytes, or red blood cells (RBCs)
Leukocytes, or white blood cells (WBCs)
Platelets
Hematocrit
Percentage of total blood volume comprised of RBCs (~45% men, 40% women)
Blood vessels
Blood transported in closed system of vessels that begins & ends @ heart
Platelets involved with
clotting
3 major types of vessels
arteries, capillaries, & veins
Arteries carry blood
away from heart
Veins carry blood
toward heart
Capillaries
contact tissue cells & directly serve cellular needs by moving blood both in and out of tissues
Low pressure system
veins
High pressure system
arteries
Thicker and more elastic vessel
arteries
Anastomoses or shunts
arteries, arterioles, capillaries, veins & venules are either open or selectively by-passed bc blood supply is insufficient for all vascular networks to be simultaneously open (it’s routed to where it is most needed at a particular time)
Pulmonary circuit side of heart
right
Pulmonary circuit pumps de/oxygenated blood to WHERE via WHAT
deoxygenated to lungs via pulmonary arteries
Systemic circuit side of heart
left
Systemic circuit pumps de/oxygenated blood to WHERE via WHAT
oxygenated to whole body via arteries
Systemic circuit returns de/oxygenated blood to WHERE via WHAT
Returns deoxygenated blood to right heart via veins
Pulmonary circuit returns de/oxygenated blood to WHERE via WHAT
Returns oxygenated blood to left heart via pulmonary veins
Epicardium function
lubricative outer covering of heart
Myocardium function
provides muscular contractions that eject blood from heart chambers
Cardiac cycle
systole (contraction phase) and diastole (relaxation phase)
Valves
promote blood flow in 1 direction
Pulmonary valve
top left-right ventricle to pulmonary artery
Tricuspid valve
bottom left-right atrium to right ventricle
Aortic valve
top right- left ventricle to aorta
Bicuspid valve
bottom right- left atrium to left ventricle
Left ventricle
walls are thicker, stronger, and more elastic than others bc it pumps blood throughout whole body
More time in diastole/systole in exercise than rest
systole
More time in diastole/systole at rest than exercise
diastole
BP
Force per unit area exerted on wall of a blood vessel by its contained blood
Measured in reference to systemic arterial BP in large arteries near heart
mm Hg
Differences in BP w/in vascular system provide driving force that keeps blood moving from higher to lower pressure areas
Resistance
Opposition to flow
Measure of amount of friction blood encounters as it passes through vessels
referred to as peripheral resistance (PR) or total peripheral resistance (TPR)
Resistance generally encountered in…
systemic circulation
3 important sources of resistance are:
blood viscosity
total blood vessel length
blood vessel internal diameter
Resistance factors that remain relatively constant are:
Blood viscosity – thickness
Blood vessel length – longer the vessel, the greater the resistance encountered
Major determinants of peripheral resistance
Small-diameter arterioles
Fatty plaques from atherosclerosis contribute to…
a decrease in internal diameter (decreased opening for blood flow)
Fatty plaques from atherosclerosis cause:
turbulent blood flow
Turbulence dramatically increases resistance
Resistance varies
inversely with 4th power of vessel radius
Blood flow (F) inversely proportional to
resistance (R)
if R increases, blood flow decreases
Blood flow (F) directly proportional to difference in WHAT between 2 points in circulation
BP
if difference in pressure increases, blood flow speeds up
Is resistance or difference in pressure more important in influencing local blood pressure
resistance (R)
Arterial BP reflects 3 factors of arteries close to heart
1) elasticity (distensibility & recoil)
2) compliance (distensibility & lack of recoil)
3) volume of blood forced into them @ any given time
Systolic pressure
Top #
pressure exerted on arterial walls during ventricular CONTRACTION
highest reading
LEFT VENTRICLE
Diastolic pressure
Bottom #
arterial pressure during cardiac RELAXATION
lowest reading
RIGHT VENTRICLE
Pulse pressure
difference between systolic & diastolic pressure
Mean arterial pressure (MAP)
pressure that propels blood to tissues
=diastolic pressure + ⅓ pulse pressure
Blood flows along what kind of gradient
pressure; always moving from high to low
Pressure results when…
flow is opposed by resistance
Steepest change in BP occurs in…
arterioles
Systemic pressure
Is highest in aorta
Declines throughout length of pathway
Is 0 mm Hg in right atrium
Q
cardiac output: volume of blood pumped by heart per min.
4-6 L/min @ rest
= HR x stroke volume
Main factors influencing blood pressure (3)
cardiac output (Q)
Peripheral resistance (PR)
Blood volume
Q x PR =
BP
cardiac output X peripheral resistance
BP varies directly w/
Q
PR
Blood volume
Normal BP
~120/80 mmHg
High BP
> = 140/90 mmHg(hypertension)
Low BP
<= 90/60 mmHg (hypotension)
Factors That Increase Arterial Blood Pressure
blood volume increases heart rate increases stroke volume increases blood viscosity increases PR increases
Venous BP alone is too low to promote adequate blood return & is aided by
respiratory pump: pressure changes by ventilation
muscular pump: skeletal muscles move blood toward heart
1 way valves in peripheral veins prevent back flow against gravity
Contraction of heart depends on electrical stimulation of…
myocardium
Impulse is initiated in…
right atrium (deoxygenated blood side)
Electrocardiogram (ECG/EKG)
records electrical activity of heart
abnormalities may= coronary heart disease
ST segment depression may= myocardial ischemia
P-wave
atrial depolarization
QRS complex
ventricular depolarization
T-wave
ventricular repolarization
Stroke volume (SV)
volume of blood ejected per ventricular contraction
usually L ventricle
Parasympathetic nervous system:
increase/decrease HR?
via?
affects SA node how?
decrease in HR
vagus nerve
inhibits SA node
Sympathetic nervous system:
increase/decrease HR?
via?
affects SA node how?
increase in HR
cardiac accelerator nerves
stimulates SA node
Hormones that increase heart rate
epinephrine & thyroxine
Regulates SV
End-diastolic volume (EDV)
average aortic BP
ventricular contractility
EDV
Frank-Starling Law
volume of blood in ventricles @ end of diastole
“preload”
Frank-Starling mechanism (law)
Greater preload results in stretch of ventricles & a concomitantly forceful contraction (because myocardium has elastic qualities)
EDV affected by
Venoconstriction (+) Skeletal muscle pump (+) Respiratory pump (+)
Average aortic pressure
pressure the heart pumps against to eject blood
“afterload”
aortic pressure inversely related to SV
Ventricular contractility
increased contractility=higher stroke volume
Cardiac output=
cardiac rate x SV
Plasma
liquid portion of blood
-ions, proteins, hormones
Cells
solid portion of blood
-RBC, WBC, platelets
Hematocrit %
~ 40-45%
2 major adjustments of blood flow
increased cardiac output
redistribution of blood flow (less blood to visceral organs and more to active muscles)
Q (cardiac output) increases due to:
increased HR and SV (plateaus @ ~40% VO2 max)
Circulatory responses to exercise
HR and BP depend on type, intensity, & duration of exercise, environmental conditions, & emotional state
Rest -> exercise
rapid increase in HR, SV, & Q
Incremental exercise
HR & Q
-increase linearly w/ increasing work rate
-plateaus @ 100% VO2max
systolic BP
-increases w/ increasing work rateAt same oxygen uptake arm work results in higher:
HR: Due to higher sympathetic stimulation
BP: Due to vasoconstriction of large inactive muscle mass
Prolonged exercise
Q maintained by: gradual decrease in SV & increase in HR
cardiovascular drift: bc dehydration & increased skin blood flow (rising core temp)
Cardio control during exercise
- initial signal to “drive” comes from higher brain centers
- Fine tuned feedback:
-In skeletal muscle
-chemoreceptors: detect changes in blood
chemistry
-mechanoreceptors: detect joint actions
-baroreceptors: detect BP changes
Muscular endurance
ability of muscle to sustain high intensity, repetitive, or static exercise repeated in 1-2 min bursts
muscular strength & anaerobic development
Cardiorespiratory endurance
ability of whole body to sustain prolonged, steady-state exercise
cardiovascular & respiratory system (aerobic) development
VO2 Max
highest rate of O2 consumption possible during max exercise
can be increased with endurance training
Submax endurance capacity
determined by VO2 max & lactate threshold
*more difficult to evaluate
can be increased with endurance training
Heart size w/ training
Left ventricle size & wall thickness increase
Fick equation evaluates?
a-VO2 diff.
oxygen uptake by active muscle tissue
arteriovenous volume of oxygen: diff in O2 concentration in arteries and veins
RHR
decreases with endurance training
Bradycardia
slow HR
RHR: 30-40 bpm
Tachycardia
fast HR
RHR: >= 90 bpm
Submax HR during exercise
decreases with training
Max HR during exercise
remains unchanged
Gradience
moving from an area of high to low
can be anything (temp./concentration/etc.)
Systemic Circulation Overview
- blood leaves via arteries that become capillaries
- O2 and nutrients diffuse across capillary walls and enter tissues
- CO2 and waste is removed from tissues into the blood
- O2 deficient blood goes to lungs where it releases CO2 and picks up O2 at alveolar sacks
- O2 rich blood returns to the heart
What happens if there is no gradience?
there is no driving force
What is the blood made up of?
-plasma and formed elements
what are the formed elements in the blood?
- erythrocytes (RBC)
- Leukocytes (WBC)
- platelets
What do RBC’s do?
carry oxygen and carbon dioxide
What are the two circuit systems?
pulmonary and systemic
What is the flow of blood in the heart? IN DETAIL
enters through vena cava to the right atrium, through the tricuspid valve to the right ventricle, through the pulmonary valve, to the pulmonary artery to the capillaries to the lungs (where co2 and 02 exchange takes place and waste is removed), back to capillaries to the pulmonary vein, to the left atrium, to the left ventricle, through the aortic valve, to the aorta, and finally to the rest of the body
Blood is the body’s only what?
fluid tissue
Why would hematocrit be low?
because o2 supply is low and rbc’s carry o2 and rbc’s make up hematocrit
plasma
cellular portion of the cell
Percentages in the blood?
Plasma-55%
Erythrocytes-45%
Buffy coat(leukocytes and platelets)- <1%
the process of separating blood through a _______
centrifuge
Arterial Vessels
high pressure
thick, strong walls
elasticity in walls
Venus Vessels
low pressure
no elasticity in walls
Facts about the circulatory system
- blood supply is not sufficient enough to have all vascular networks open at one time
- blood is prioritized and sent to the areas where it is needed most (the brain is most frequent)
- to reroute blood, arteries/arterioles, veins/venules, and capillaries are either open or selectively bypassed by shunts or anastomoses
if sphincters are closed…..
shunts or anastomoses are open
Superior and Inferior Vena Cave
- low pressure systems
- one way valves
Aneurism
weakness within the heart wall
Chordae tendineae and papillary muscle
support valve inside the chamber
interventricular septum
division between the left and right side of the heart
Pulmonary circuit
low pressure system that pumps deoxygenated blood to lungs (PA) and returns oxygenated blood to heart (PV)
Systemic Circuit
high pressure system that carries oxygenated blood to entire body (aorta), and returns deoxygenated blood to the right side of the heart (veins or venus system)
Coronary Vessels
Two pairs of blood vessels (the coronary arteries and coronary veins) that supply the muscles of the heart itself
Myocardium
provides muscular contractions that eject blood from the heart chambers
epicardium
serves as a lubricative outer covering
layers of the heart muscle (outer to inner)
pericardium, epicardium, myocardium, endocardium
during exercise, systole or diastole is longer?
systole is relatively longer
in the absence of blood pressure?
someone will die
BP in arteriole system?
force per unit area exerted on wall of blood vessel by its contained blood
BP in vascular system?
provides the driving force that keeps blood moving from high to low pressure areas (pressure gradient)
BP is expressed?
millimeters of mercury per g (mm Hg)
Artificially Induced Polycythemia
hematocrit levels are up
thick blood (high viscosity)
dehydration
In terms of resistance, the longer the blood vessel….
the greater the resistance encountered
orm of low blood pressure that happens when you stand up from sitting or lying down
orthostatic hypotension
In reference to resistance, vessel internal diameter….
- changes are frequent
- varies inversely(internally) with 4th power of vessel radius
Vessel radius is normal what?
1/2 diameter
carotid intima-media thickness
resistance in a major artery
