Reading 3 (80-82, 88) Flashcards
The heart is a ____ that pushes _____ around the body. Blood enters the heart at a ______ pressure and leaves at a ____ pressure, providing the force to propel the blood through the _____ system.
The heart is a PUMP that pushes BLOOD around the body. Blood enters the heart at a LOW pressure and leaves at a HIGHER pressure, providing the force to propel the blood through the CIRCULATORY system.
Blood returning from the body is sent to the ____ side of the heart and then to the _____ to pick up ____ and release _____. The oxygenated blood is sent to the ____ of the heart and back to the _____, where ____ is released and _____ is collected.
Blood returning from the body is sent to the RIGHT side of the heart and then to the LUNGS to pick up OXYGEN and release CO2. The oxygenated blood is sent to the LEFT of the heart and back to the BODY, where O2 is released and CO2 is collected.
What does the complete division of the heart insures
No mixing of deoxygenated blood (in right side) and oxygenated blood (in left side)
What does it mean that the mammalian heart is auto rhythmic
Will continue to beat if removed from body (and kept at appropriate sln)
What are heart contractions dependent on
Rhythm comes from w/in heart itself (NOT BRAIN)
What is responsible for the pumping action of heart
Myocardium (large strong muscle fibers) and other cardiac muscle cells are weakly contractile and produce or conduct rhythm for rest of heart
How does the SA node act as the pacemaker for the heart? Describe the electrical
Cells in SA node rhythmically produce APs which spread via gap jxns to fibres to both atria -> resulting contraction pushes blood into ventricles -> electrical activity moves into AV node and AP spreads slowly thru AV node -> then AP spreads rapidly thru Bundle of His and Purkinje fibres to excite both ventricles
Where are the semilunar valves located
- btwn ventricle and main artery on each side of heart
When heart relaxed what happens to the semilunar valve and blood flow
- high arterial pressure shuts SV valves and prevents BF from artery back into ventricle
What happens when ventricular pressure is greater than arterial pressure
- ventricular contraction inc pressure of blood in ventricle. When ventricular pressure greater than arterial pressure, SV valves open and blood flows into arteries. then myocardium relaxes and ventricular pressure declines, and SV valves close
The cardiac cycle involves _____ of the atria and ventricles which are triggered by ____ in the myocardial cells
The cardiac cycle involves SEQUENTIAL CONTRACTIONS of the atria and ventricles which are triggered by APs in the myocardial cells
The combined electrical activity of myocardial cells produces electrical currents that spread thru _______
the body fluids
The regular pattern of signals produces by the heart is called _____
the electrocardiogram
The components of ECG are correlated to electrical activity in _____
atria and ventricles
P wave corresponds to
Atrial depolarization
QRS complex corresponds to
Atrial repolarization and ventricular depolarization
T wave corresponds to
ventricular repolarization
The pulses of blood moving in arteries can be recorded using a device known as
Plethysmograph
The arterial system fxns as a _____ reservoir. Blood enters via the ___ and exits thru the _____.
The arterial system fxns as a PRESSURE reservoir. Blood enters via the HEART and exits thru the CAPILLARIES.
Fxn of signals from the ANS
- Control the tone of smooth muscle sphincters around the arterioles -> thus controlling distribution of blood to various organs
What is the distribution of blood to particular organ influenced by
- Local conditions e.g. if cells require arterial blood due to dc pH or O2, or inc CO2, smooth muscle sphincters open to permit blood into particular capillary beds
How does blood flow changed compared to at rest vs. exercise
During exercise:
- BF to gut dec
- BF to working skeletal muscles inc
- BF around circulatory system inc several fold as result of inc CO
Stats indicate that people who can’t cope with stressful events run a ______ risk of suffering from CHD. They demonstrate __________, _______, ________, ______ during stressful events
- Stats indicate that people who can’t cope with stressful events run a 7X HIGHER risk of suffering from CHD
- They demonstrate AGGRESSION, IMPATIENCE, DISSATISFACTION, IRRITABILITY during stressful events
Another name for variability in R-R intervals
Heart rate variability (HRV)
What is HRV (heart rate variability) and used for?
- Analysis of variability in R-R intervals in ECG can indicate imbalance btwn sympathetic n vagal influences on heart
- Comparison of sympathetic and vagal activity can be used as measure of stress
How can HRV be studied? In this case what did we use
- mathematical modeling of HR regulatory systems
- Non linear methods for determining indices for regulatory fxns
- time domain methods to determine deviation of successive N-N (normal R-R) intervals
- Spectral domain methods to determine the power spectral density of definitive frequency components of the ECG
PSA (power spectral analysis) of HRV of subject. Involves mathematical transformation of ECG record to yield power spectrum and analysis of spectrum to determine density of defined frequency ranges in spectrum
What is ULP
Power density # for ultra low frequency range (<0.003 Hz), and its prognosis of sudden cardiac death taken from 24 hr ECG recording highly accurate
what is VLP
Power density # for very low frequency range (0.003-0.04 Hz), and thought to be connected to thermoregulation, the renin-angiotensin system, and changes in PA
what is LP
Power density # for low frequency range (<0.04-0.15 Hz) that is generated mainly by sympathetic activity.
- Baroreceptor (pressure) modulation major component of LP power
what is HP
Power density # for high frequency range (0.15-0.40 Hz), and is derived from VAGAL activity which is modulated by RESPIRATION
What does LP and HP mainly represent respectively and their ratio mean
LP = sympathetic activity; HP = vagal activity. Their ratio (HRV ratio) good indicator of sympathetic-vagal balance
- ratio used to assess balance of ANS in various diseases
How does LP and HP change w/stress
Stress accompanied w/inc power spectral density (PSD) of LP (sympathetic) and dec PSD of HP (vagal activity)
What does a HRV ratio of 0.83 indicated
Vagal activity has greater influence on HR than symapthetic system
What is the usual HRV of young people
high as 1.5
What is happening in HRV exp
- PSA of HRV of subject determined from their ECG
- mathematical transformation of ECG to yield its power spectrum n analysis of spectrum determine density of defined frequency ranges in spectrum
- 1st step in analysis is to express successive R-R intervals as fxn of time/heartbeat #
- 2nd step convert result of 1st step (tachogram) to HRV power spectrum using Fast Fourier
- 3rd step determine PSD of certain frequency ranges in HRV power spectrum
What does the magnitude of the PSD in certain frequency indicate
Relative amt of activity in specific parts of ANS and lvl of stress in subject
HRV ratio of 6.9 indicates
sympathetic activity has greater influence on HR than vagal activity
Systolic and diastolic for high BP?
Systolic >139, diastolic >89
LP and HP of person with hypertension
Higher LP and lower HP value than non hypertensive persons
What is a frequent complication of diabetes and what can it result
neuropathy can result in fxnal autonomic denervation causing patients to develop fast, fixed HR. causes diabetics to have lower RR variance and smaller R-R interval. power spectrum look NORMAL at REST but DIMINISHED INC IN LP AND DIMINISHED DEC IN HP when STANDING/TITLED
What does smoking act synergistically with
- hypertension, oral contraceptives to inc risk of heart attack
LP and HP values of smokers?
Higher LP and lower HP values than non smokers; HRV ratios greater than 1.5
