Chapter 7 Revised Flashcards
Three major circulatory elements
Heart, Blood vessels, blood
Heart generates ____ to drive blood through vessels
Pressure
T/F: Blood flow must meet metabolic demands.
True
Cardiovascular System Major Functions
Delivers O2 and Nutrients
Removes CO2 and other waste
Transports hormones and other molecules
Temperature balance and fluid regulation
Acid-base balance
Immune function
Right side of heart: _____ circulation
Pulmonary
Superior and inferior vena cavae ——>
RA —> tricuspid valve —> RV —> pulmonary valve —> pulmonary arteries —> lungs
Left side of heart: ____ circulation
Systemic
Lungs —>
Pulmonary veins, LA, mitral valve, LV, aortic valve, aorta
What is myocardium?
Cardiac muscle
4 LV characteristics
Must pump blood
Thickest walls
LV hypertrophies with exercise and with disease
But exercise adaptations vs disease adaptations very different
Right coronary artery supplies ___ side of heart
Left (main) coronary artery supplies ___ side of heart
Right
Left
Coronary artery disease
Atherosclerosis
Which muscle type is being described?
- large, long, unbranched, multinucleated
- intermittent, voluntary contractions
- Ca2+ released from SR
Skeletal muscle
Which muscle type is being described?
- Small, short, branched, one nucleus
- Continuous, involuntary rhythmic contractions
- Calcium-induced calcium release
Myocardial cells
Rank the steps of calcium induced calcium release
- DHP receptors in T-tubule are stimulated and open
- AP spreads along sarcolemma down T-tubules
- Extracellular Ca+2 to enter cell, but insufficient to cause contraction
- Instead, triggers ryanodine receptors
AP, DHP, Extracellular, Instead
Myocardial cells fiber type is most similar to type ___ of skeletal muscle.
I
Cardiac muscles fibers connected by regions called _______.
Intercalated discs
Holds cells together
Desmosomes
Rapidly conduct action potentials
Gap junctions
Cardiac muscle has the unique ability to generate its own electrical signal called
Spontaneous rhythmicity
Electrical impulse:
Right atrium —> _______.
Throughout the entire heart
Starting point: ________
Sinoatrial Node
Special cardiac cells generate and spread electrical signal
Spontaneous rhythmicity
Initiates contraction signal
SA node
Delays/relays signal to ventricles
AV node
relays signal to RV,LV
AV bundle (bundle of his)
Send signal into RV,LV
Purkinje fibers
Divides into right and left bundle branches
AV bundle
-Decreases force of contraction
- Decreases HR below intrinsic HR
- Intrinsic HR: 100 beats/min
- Normal Resting HR (RHR): 60 to 100 beats/min
- Elite endurance athlete: 35 beats/min
Parasympathetic
- Increases force of contraction
- Increases HR above intrinsic HR
- Determines HR during physical, emotional stress
- Maximum possible HR: 250 beats/min
Sympathetic
All mechanical and electrical events that occur during one heartbeat
Cardiac cycle
T/F: Diastole is twice as long as systole
True
1/3 of cardiac cycle time
Ventricular systole
2/3 of cardiac cycle time
ventricular diastole
Blood leftover in ventricle =
End-systolic volume
At end, blood in ventricle =
End diastolic volume
Volume of blood pumped in one heartbeat
Stroke volume
% of EDV that was SV
Ejection fraction
Normal ejection fraction for healthy, active young adult at rest
60%
Heart Failure: ___%
40
Total volume of blood pumped per minute
Cardiac Output
Carry blood away from heart
Arteries
Control blood flow, feed capillaries
Arterioles
Site of nutrient and waste exchange
Capillaries
Collect blood from capillaries
Venules
Carry blood from venules back to heart
Veins
Pressure exerted by blood on arterial walls
Blood Pressure
Highest pressure in artery
Systolic pressure
Lowest pressure in artery
Diastolic pressure
Average pressure over entire cardiac cycle
Mean arterial pressure
MAP = 2/3 DPB + 1/3 SBP
Ok
Required by all tissues
Blood flow
Blood flow =
Change in pressure / resistance
Force that drives flow
Pressure
Force that opposes flow
Resistance
Diverts blood to regions most in need
Vasoconstriction (VC) or vasodilation (VD)
Also known as resistance vessels
Arterioles
Site of most potent VC and VD
Arterioles
Liver, kidneys receive ___ of Q
50%
Exercise muscles receive ___% of Q
80
Arteriole walls can respond to _____ mechanisms
Local control
Ability of local tissues to constrict or dilate arterioles that serve them
Intrinsic control
Three types of intrinsic control
Metabolic mechanisms (VD)
Endothelial mechanisms (mostly VD)
Myogenic mechanism (VC, VD)
Redistribution of flow by the nervous system
Extrinsic neural control
___________ innervates smooth muscle in arteries and arterioles
Sympathetic nervous system
Increased sympathetic activity leads to
Increase VC of area
Decrease sympathetic activity leads to
Decrease VC ; passive VD
At rest, veins contains ___ blood volume
2/3
______ can be liberated, sent back to heart and into arteries
Venous reservoir
T/F: Upright posture makes venous return to heart more difficult
True
2 mechanisms that assist venous return
Muscle pump & one-way venous valve
Blood pressure maintained by
Autonomic reflexes
Sensitive to changes in arterial pressure & adjust HR and arterial pressure back to normal
Baroreceptors
3 major functions of blood
- Transportation
- temp regulation
- Buffers acids from anaerobic metabolism
Whole blood =
Plasma + formed elements
55-60% of blood volume
Plasma
40-45% of blood volume
hematocrit
Erythrocytes
99%
No nucleus, cannot reproduce
RBC’s
RBC’s replaced regularly via
Hematopoiesis
Oxygen-transporting protein in RBC
Hemoglobin
T/F: 250 million hemoglobin per RBC
True
Thickness of blood due to red blood cells
Blood viscosity
T/F: Water has greater viscosity than blood
False
T/F: Plasma volume must increase as red blood cells increase
True
3 Cardiac Responses
Heart Rate, Stroke Volume, Cardiac output
2 Vascular Responses
Blood Pressure, Blood flow
- point of plateau
- Optimal HR for meeting circulatory demands at a given submaximal intensity
- If intensity increases, so does steady-state HR
- Adjustment to new intensity takes 2 to 3 min
Steady state HR
What controls SV?
Preload, Contractility, and Afterload
End diastolic volume
Preload
The more the ventricles are stretched, the more forceful the contraction.
Frank-Starling Mechanism
SV ___ as the ventricular EDV increases
Increases
- Sympathetic nerve activity
- Circulating catecholamines
- The amount of free Caclium in the cytosol
Cardiac contractility
T/F: SV increases as the cardiac contractility increases
True
The aortic blood pressure that the heart must overcome to eject blood
Afterload
O2 consumption of a tissues depends on blood flow to the tissue and the the amount of O2 extracted by that tissue
The Fick Equation
Potentially dangerous but accompanies certain types of exercise
Valsalva maneuver
T/F: Low presssure collapse great veins —> decrease in venous return —> decrease in cardiac output —> decrease in arterial blood pressure
False; High pressure
_____ shunts blood away from less-active regions
- kidneys
- splanchinic circulation (liver, pancreas, GI)
Sympathetic vasoconstriction
Permits additional blood flow in exercising muscle
Local vasodilation
As temperature rises, skin __ also occurs
VD
Associated with increase core temperature and dehydration
Cardiovascular drift
HR drifts increase to compensate (__ maintained)
Q
During heavy exercise what is the cardiac output for the digestive system?
3-5%