Cardiovascular physiology Flashcards
Arterial Barocreceptors-decreasing the stretch on the baroreceptors leads to increased or decreased efferent sympathetic stimulation?
increased
What event creates the 1st heart sound
closure of the atrioventricular valves, i.e. mitral and tricuspid, at the beginning of ventricular contraction
Which band in a skeletal muscle cell contains only actin filaments (thin filaments)?
i band
What ion is responsible for the slow depolarization current in the pacemaker AP? This current accounts for the automaticity of the eSA and AV nodes.
Na+
Electrocardiogram-QRS complex represents?
ventricular depolarization
Do Perkinje fibers have fast or slow response action potentials?
fast
Name three functions of bradykinin.
increased vasodilation, increased permeability and increased pain.
Ejection Fraction=
ejection fraction=stroke volume/end diastolic volume
Blood is ___% plasma
55% -the reset is formed elements (hematocrit)
Name three physiological changes that sensed by peripheral chemoreceptors (carotid and aortic bodies).
- decreased pO2 below 60 mmHg;
- increased pCO2
- decreased pH of blood
During which period is O2 consumption by the heart the highest?
isovolumetric contraction
Electrocardiogram-T wave represents?
ventricular repolarization
If you see the ventricles contraction before the atria what has happened?
the AV node has taken over pacemaking
What events create the second heart sound?
closure of the aortic valve and pulmonary valve at the end of ventricular systole
What is the last and final resort after both the AV and SA nodes no longer function as pacemakers?
the perkinje fibers take over and cause 30-40 beats/min.
Factors that decrease systolic pressure. (3)
stroke volume, HR, compliance
What factors affect capillary exchange? (4)
factors that affect diffusion rate are: surface area, membrane thickness, concentration gradient, solubility.
Which organ has the highest blood flow per gram of tissue?
kidney
Coronary circulation consumes what % of total body O2?
10-20%
Where are the pacemaker cells located?
in the SA node usually
What is the result of a pH of 6.5 on the heart?
it blocks calcium induced calcium release causing a reduction in cardiac muscle contraction
What is afterload?
diastolic arterial pressure (proportional to peripheral resistance)
When does S3 occur?
at end of rapid ventricular filling
When is coronary blood flow highest?
during diastole (when the heart is relaxed)
Closure of the aortic and pulmonic valve occurs as S1 or S2 heart sound?
S2
Ventricular end diastolic volume is termed ___.
preload
During contraction, which bands shrink in a muscle cell?
H, I, and Z bands
Which band in a muscle cell remains the same size?
A band (dark bands)
Factors that increase systolic pressure. (3)
stroke volume, HR, compliance
Which band in a skeletal muscle cell contains myosin filaments (thick filaments)?
H band/zone
Electrocardiogram- What is masked by the QRS complex?
atrial repolarization
Factors that increase diastolic pressure. (4)
TPR, HR, stroke volume, compliance
Factors that increase pulse pressure. (2)
stroke volume (systolic>diastolic); compliance (systolic increases and diastolic decreases)
Which organ has the largest share of systemic cardiac output?
liver
Arterial baroreceptors- carotid sinus baroorecptor transmits via what nerve to the medulla?
glossopharyngeal (IX)
What becomes the primary pacemaker if the SA node is damaged?
the av node
Explain how th eCA++/ Na+ exchanger pump can be used to treat congestive heart failure.
drugs such as digitalis block Na+/K+ exchangers thus increase intracellular Na+ concentrations which reverses the directionof the Ca+/Na+ exchanger bringing more CA+ into the cell causing muscle contraction.
Closure of the mitral and tricuspid valve occur as an S1 or S2 hear sound?
S1
During exercise, cardiac output (CO) increases as a result of an increase in ____ and ____?
stroke volume and heart rate
electrocaardiogram- Where is the pacemaker of the heart?
SA node in right atrium
Factor II is also known as?
prothrombin
During what phase do coronary arteries fill?
diastole
If after-load is decreased, what happens to stroke volume?
increased
Forces that move fluid out of capillary?
capillary pressure (Pc) and interstitial fluid colloid osmotic pressure.
Ejection fraction is an index of ventricular ____?
contractility
Electrocardiogram-ST segment represents?
isoelectric, ventricles depolarized
What three entities affect stroke volume?
contractility, after-load and preload
What is the technical term for the migration of a white blood cell through an endothelium?
diapedesis
What may cause an S4 heart sound?
high atrial pressure/ stiff ventricle
Electrocardiogram-QT interval represents
mechanical contraction of ventricles
Isovolumetric contraction is the period between ___ valve closure and ___ valve opening.
mitral / aortic
Name three ways that cardiac muscle differs from skeletal muscle with regards to its electrophysiology.
- action potential has a plateau which is due Ca++ influx.
- cardiac nodal cells spontaneously depolarize, resulting in automaticity.
- cardiac myocytes are electrically coupled to each other by gap junctions.
Are the number of erythrocytes increased or decreased at thigher altitudes?
increased
Electrocardiogram-a completely erratic rhythm with no identifiable waves is termed?
ventricular-fibrillation
Define after-load.
the pressure that a chamber of the heart must generate in order to eject blood.
What is pulse pressure?
systolic-diastolic blood pressure
Define pre-load
preload is the pressure stretching the ventricle of the hear, (1) after atrial contraction and subsequent passive filling of the ventricle
Arterial baroreceptors-aortic arch baroreceptor transmits via what nerve to the medulla?
vagus (X)
What ion is key for the action potentials of the SA and AV node?
Na
Myocardial action potential -During resting potential, the myocyte membrane is highly permeable to what ion?
K+
Blood-borne vasoconstrictors? (3)
endothelial cells: Ang II, Endothelian platelets: Thromboxane
Pulse pressure correlates to what other measure?
stroke volume
What is the effect of inspiration on heart rate?
reflex tachycardia
High atrial pressure/ stiff ventricle causes which heart sound?
S4
What happens to stroke volume in pregnancy?
increases
Factors that decrease diastolic pressure. (4)
TPR, HR, stroke volume, compliance
Blood-borne vasodilators? (2)
NO, Prostacydin
What is the formula for mean arterial pressure?
CO X TPR
Electrocardiogram- U wave is caused by?
hypocalemia or hypokalemia
Forces that move fluid into capillary?
interstitial fluid pressure (PI) and plasma colloid osmotic pressure.
Name the fibers which carry electrical impulses to the ventricles.
perkinje fibers
MAP=
CO x TPR
Aortic and pulmonic valve closure causes which heart sound?
S2
Define poikilocytosis
varying shapes
Arterial Baroreceptors-What is the effect of a carotid massage?
it increases the pressure in the carotid artery,increases the stretch of the baroreceptors, and leads to a decrease in heart rate.
Cardiac Output=
cardiac output=stroke volume x HR
IN which direction does the contraction of the heart proceed in ?
apex–>base
What is the effect of expiration on heart rate?
reflex bradycardia
Control of mean arterial pressure (MAP)-Name four compensatory mechanisms that are activated when barorecptors detect low MAP?
- heart rate increases (beta1), contractility increases (beta1)
- venous tone/venous return increases (alpha)
- TPR increases (alpha)
- kidneys retain sodium and H2O (via renin-angiotensin-aldosterone system)
What does Starling’s law say?
prestretched muscle contracts more forcefully
Stroke Volume=
stroke volume= end diastolic volume- end systolic volume
Electrocardiogram-P wave represents?
atrial depolarization
Coagulation Cascade: Factors requiring phospholipid surface for activation?
IX and X
Arterial Baroreceptors-Hypotension leads to vasoconstriction or dilation?
vasoconstriction
Coronary circulation receives what % of cardiac output?
5-10%
Electrocardiogram-PR segment represents?
conduction delay through AV node
MItral and tricuspid valve closure causes which heart sound?
S1
Define erythrocyosis
increased number of red cells
What is the lifetime of the rbc?
120 days
