heart review and respiratory 2 Flashcards
Where is the location of the cardiac centers that regulate heart rate?
medulla oblongata
We have said that the heart has automaticity and rhythmicity, can external influences affect pacemaker activity? How?
ECG or electrical differences
Why is an ECG good for medical fields?
it can measure the electrical activity in the heart and we can see if the heart is working abnormally
Does the ECG measure one action potential in the heart?
ECG measures the p wave, r wave, and t wave.
What electrical event does the P wave represent?
depolarization of the atria
An abnormal QRS complex would indicate an abnormality in what area of the heart?
cardiac conduction
What events are occurring during the PR interval? An increase in the PR interval might indicate an abnormality in what region of the heart?
atrial excitation until beginning of ventricular excitation. cardiac dysfunction
What are the 3 phases of the cardiac cycle?
1- Ventricular filling
2-ventricular systole
3-isovolumetric relaxation (early diastole)
If the atria could not contract what would happen to ventricular filling?
blood would not get pumped into the ventricles
diastole
relaxed
systole
contract
Explain what events are occurring during isovolumetric contraction and why they are necessary.
causes ventricular pressure to be greater than atrial pressure which produces the first heart sound
What causes ejection of blood from the heart?
The heart contracting which is a result of pressure changes
What are EDV and ESV?
EDV- end diastole volume and end systolic volume
What are the determinants of blood pressure?
the rate of blood flowing out of the heart per minute known as Q(cardiac output) which is determined by HR and SV
What does chronotropic and inotropic mean?
chronotropic mean time change and isotropic means fiber change
What is the difference between preload and afterload?
preload is the amount of pressure within the ventricle prior to contraction. Afterload is the pressure in the arteries outside of the semilunar valves that must be reached in the ventricles before valves can open.
What would be the effect of an increase in preload on Q?
it would increase cardiac output and increase BP
How does contractility affect ESV?
because increase cardiac output determines SV and SV is equal to EDV-ESV
What is a normal blood volume? What is a normal Q at rest?
120/80 and 60-100bpm
What is the Frank-Starling mechanism?
describes the relations between SV and EDV. It determines that they are proportional and the ventricles will expel as much blood as they receive due to a greater force of contraction
How would an increase in afterload affect cardiac output?
it would decrease cardiac output
what is SV?
the amount of blood pumped per contraction of the ventricle
How would an increase in carbon dioxide concentration affect HR? Where would this change be sensed (What type of receptor and where are those receptors located)?
increase HR and the change will be sensed by baroreceptors located in the aortic arch and internal carotids which can sense changes in pressure
What are the exchange vessels of the body?
capillaries which are the smallest vessels
What forces drive capillary exchange? What is the source of these pressures (i.e., how can they change?)
tissue and blood. nutrients gases wastes and hormones
What is the function of the endothelium?
provides a smooth surface for laminar blood flow. (prevents damage to platelets and blood cells.
how is blood flow calculated?
change is pressure over resistance
what is the most important factor when regulating blood flow?
local factors (metabolites), neural factors , and hormonal factors
what controls vasomotion?
the activation of smooth muscle cells
Why is blood flow fastest in the aorta? Why does it slow down?
continued friction, decreased radii of the arterioles and capillaries, and total cross-sectional area of all capillaries are much greater than that of the aorta.
respiration
the process of ventilation of the lungs and exchange of oxygen and CO2 between to atm and the blood and between the blood and the tissue
Where are the breathing centers located in the brain?
medulla oblongata
