Physiology- Cardio Flashcards
What are the 3 main plasma proteins?
Albumin
Globulins
Fibrinogen
What is the major blood electrolyte?
sodium
Where does erythropoiesis occur?
bone marrow
Cessation of bleeding is known as what?
hemostasis
What is the role of platelets in hemostasis?
they stick to the injured site causing a platelet plug
What do you call a clot that includes RBCs?
a thrombus
What makes up a clot?
platelet plug plus fibrin
Vitamin K is important for which clotting factors?
II, VII, IX, X
What initiates the intrinsic pathway of the blood coagulation cascade?
blood coming into contact with exposed collagen of the damaged tissues.
What mineral is needed for proper clotting?
calcium
What is the insoluble substance that precipitates out at an injury site?
fibrin
Hemophilia is a genetic absence of what clotting factors?
Hemophilia A: Factor VIII
Hemophilia B: Factor IX
What substance dissolves clots?
Plasmin
What substance cleaves fibrinogen into fibrin?
Thrombin
Myocardial cells have more of this organelle due to its high oxidative capacity:
mitochondria
What cellular feature allows the heart to contract as a syncytium?
gap junctions between the muscle cells
How do T tubules differ between cardia and skeletal muscle?
Cardiac: T tubules contain extracellular fluid high in calcium
Skeletal: T- tubules contain extracellular fluid that is low in calcium
What structure brings depolarization inside the cardiac muscle and helps regulate cytoplasmic calcium?
t tubules
What prevents tetanic contraction in cardiac muscle?
the long cardiac action potential
What aspect of the action potential prevents a second action potential from taking place?
long refractory period of plateau period
What is the originator of the cardiac action potential?
the SA node
What property allows the SA node to function as a primary pacemaker?
small cell size allows it to spontaneously depolarize
What acts as a delay station for the action potential?
The AV node
Why does the AV node delay the action potential?
to allow atrial muscle to depolarize before ventricular muscle, to allow for filling
What can act as a secondary pacemaker in pathological conditions?
the AV node
What allows for rapid conduction of the action potential?
Bundle of His
Bundle Branch fibers
Purkinjie fibers
Specialized tracts
What is the sequence of electrical impulse in the heart?
SA node–> specialized tracts–> AV node and atrial muscle–> Bundle of HIS–> bundle branches–> Purkinjie fibers–> ventricular muscle
What serves to depress the heart rate at rest by slowing down the SA node?
parasympathetic nervous system
How does the sympathetic nervous system affect conduction through the electrical system?
it speeds up conduction of the action potential and therefore increases heart rate
What nerve has the greatest influence on the heart?
the vagus nerve
What is the affect of vagal stimulation on the heart?
It serves to slow the conduction of action potentials through the AV node due to the parasympathetic nerve fibers
How does norepi affect heart contractility?
it increases heart contractility
In which phase do the ventricle fill?
late diastole
In which phase do we get isovolumetric contraction?
early systole
What phase of the cardiac cycle uses up the most energy?
the isovolumetric contraction of early systole
What is the purpose of isovolumetric contraction?
to build up the pressure so as to overcome the high aortic pressure
In which phase is ejection?
late systole
When is the relaxation phase?
early diastole
What causes heart sound 1?
closing of atrioventricular valves (mitral and tricuspid)
What causes heart sound 2?
closing of pulmonic and aortic valves
When in the cycle is S1?
late diastole/early systole
When in the cycle is S2?
end systole/ early diastole
What records electrical activity of the heart?
EKG
What information do we get from an EKG?
heart rate, rhythm, axis of the heart
What on an EKG marks atrial depolarization?
P wave
What on an EKG marks ventricular depolarization?
QRS complex
What on an EKG marks ventricular depolarization?
T wave
What 2 things influence cardiac output?
heart rate and stroke volume
How does the heart adapt to hypertension?
increases wall thickness–> cardiac hypertrophy
cardiac dilation
What are the 3 major substrates for cardiac metabolism?
fatty acids, glucose, glycogen breakdown
What are 3 minor substrates for cardiac metabolism?
Lactic acid, ketones, intramuscular triglycerides
What is the major limitation of energy metabolism by myocardium?
coronary blood flow delivering oxygen
What 2 factors determine oxygen consumption by the myocardium?
- wall tension in the heart that must be overcome e.g. during isovolumetric contraction
- Isotonic contraction to eject the blood
What property of blood vessels helps push blood through the arteriole system?
elastic tissue
What property of blood vessels does smooth muscle provide?
its ability to contract and dilate allows blood to be shunted from one area to another
What protects blood vessels against distension?
the fibrous nature of the tissue
What type of circulation has few controls, and is a low pressure/low resistance system?
pulmonary circulation
What serves as a conduit for blood?
arteries
What types of blood vessels are resistance vessels due to their smooth muscle?
arteries and arterioles
What blood vessel in involved in nutrient and waste exchange?
capillaries
What type of capillary excludes proteins and cells from passing through?
Continuous capillaries
What type of capillary excludes cells? Where are they found?
fenestrated capillaries, found in the kidney
What type of capillary allows cells and protein to pass through? Where are they found?
sinusoidal/ discontinuous
found in liver, bone marrow, spleen
What blood vessels act as capacitance vessels?
veins and venules
What increases venous return?
vasoconstriction
Which blood vessels have valves?
veins and venules
What are the 4 pressures that affect capillary exchange?
- plasma oncotic pressure
- plasma hydrostatic pressure
- interstitial oncotic pressure
- interstitial hydrostatic pressure
Which of the 4 capillary pressures favors filtration?
- plasma hydrostatic pressure
2. Interstitial hydrostatic and oncotic pressure
Which of the 4 capillary pressures is actually a negative pressure or “suction”?
interstitial hydrostatic pressure
What are 3 mechanisms for edema?
- increased plasma interstitial pressure
- decreased plasma oncotic pressure
- increased interstitial oncotic pressure
How will decreased blood protein synthesis cause edema?
by decreasing plasma oncotic pressure
What will influence lymph flow?
smooth muscle tone
skeletal muscle contraction
Pressure in the right atrium or the vena cava at the level of the heart is known as what?
central venous pressure
What will increase venous blood flow and decreased venous pressure?
skeletal muscle contraction
Where are baroreceptors located?
aortic arch and carotids
What do baroreceptors sense?
blood pressure
What kind of neurotransmitters are released when baroreceptors are stimulated by high blood pressure?
inhibitory neurotransmitters
What do inhibitory neurotransmitters accomplish with relation to blood pressure?
decrease in sympathetic firing that innervate smooth muscle, causing vasodilation
What is accomplished by stimulation of baroreceptors?
decrease in blood pressure due to the vasodilation
Where are chemoreceptors located?
aortic arch and carotids
What are chemoreceptors sensitive to?
low blood oxygen levels as a result of decreased blood flow due to low blood pressure
What kind of neurotransmitter is released when chemoreceptors are stimulated by low blood pressure?
excitatory neurotransmitters
What to excitatory neurotransmitters do with relation to blood pressure?
increase sympathetic firing down neurons that innervate smooth muscle of blood vessels –> vasoconstriction
What is accomplished by the stimulation of chemoreceptors?
an increase in blood pressure by vasoconstriction
How does increased vagal output cause a decreased blood pressure?
via its parasympathetic effects that cause decreased heart rate –> decreased CO–> decreased BP
How does the kidney affect blood pressure?
via the renin angiotensin system: dec BP –> dec GFR–> renin released–> aldosterone release –> kidneys reabsorb Na and water–> increase in blood volume –> increased BP
How doe ADH affect blood pressure?
low BP –> ADH release–> kidney holds onto water–> increased blood volume –> inc BP
In metabolic control of blood flow, decreased oxygen causes release of metabolite (CO2, lactate etc.) which causes what?
vasodilation of blood vessels, metabolic acidosis
what is the name of the control that protects against high blood pressure damage?
autoregulation
What tissue is best at auto regulation?
the brain
What is the net result of blood vessels on auto regulation?
vasoconstriction
What is the long term control of blood flow called (ie. compensation for some type of tissue ischemia)
angiogenesis
What is the primary catecholamine for alpha adrenergic receptors?
norepinephrine
Which vascular beds have primarily alpha receptors?
skin, renal, splanchnic vasculature
What affect does Norepi have on smooth muscle cells in the vascular beds?
vasoconstriction
What is the primary catecholamine for beta 2 receptors?
epinephrine
Which vascular beds have primarily beta 2 receptors?
coronary and skeletal muscle vessels
What affect does epic have on smooth muscle in the vascular beds?
vasodilation
Which of the ANS branches has the most control over circulation?
sympathetics via norepi/epi
Which vascular beds are over perfused at rest?
skin, splanchnic and renal
Brain ischemia caused by and increase in CSF pressure is known as what?
Cushings reflex
When, during the cardiac cycle, are the coronary arteries perfused?
during diastole
