Circulatory Flashcards
What is perfusion?
flow of blood through tissue
What is Ischemia?
inadequate blood flow. Waste builds up
what is Hypoxia?
reduced supply of oxygen in the blood
Does exchange happen in arterioles?
No
What is angiogenesis?
Formation of new blood vessels by proliferation of epithelial cells
What prevents backflow of blood?
Venous Valves
What happens during diastole?
ventricles relax, blood flows in from atria. Atria contract
What happens during systole?
ventricles contract, AV valves shut
Which is longer Diastole or Systole?
Diastole
What is stroke volume?
amount of blood pumped with each systole
what is cardiac output?
total amount of blood pumped per minute
What does cardiac output equal?
stroke volume x heart rate
Is the cardiac output the same in the left and right ventricles?
Yes. So backup does not occur
What are ways to increase cardiac output?
increase venous return and arterioles dilating
What are fast sodium channels?
Open first in response to depolarization to allow sodium to enter
What are slow calcium channels?
Open in response to threshold voltage and allow calcium down its gradient. Stay open longer creating plateau phase
What feature maximizes calcium entry into cardiac muscle cells once an action potential arrives?
T-Tubules
In the heart what releases calcium?
Sarcoplasmic reticulum
Which have longer refractory periods neurons or cardiac muscle?
Cardiac muscle
What are the three phases of the SA node?
Phase 0, Phase 3, Phase 4
Why does the SA node have unstable resting potential?
Due to phase 4 and sodium leak channels allowing sodium in to push for threshold
What happens at phase 0?
VG Calcium channels open
What happens at phase 3?
Repolarization. Closure of Calcium channels and opening of potassium channels.
Which node sets the rate of heart contraction?
SA node
What happens during phase 1?
Sodium channels inactivate, Potassium Channels open, Potassium efflux
What happens during phase 2?
Plateau. Calcium channels open, Calcium influx, Potassium efflux
What is the driving force in blood flow?
Difference in pressure from arteries to veins
What does Ohm’s Law tell about blood flow?
In order to change blood flow, you must change pressure or resistance
How can pressure be varied?
Changing force or rate of contraction
What is the determinant of resistance in vessels?
Precapillary sphincters
What causes an increase in resistance?
Contraction of smooth muscle by sympathetic nervous system. Vasoconstriction
What hormone provides basal level of pressure?
Norepinephrine
What are platelets?
Form plug to fix damage to blood cells
What is hemostasis?
body’s mechanism of preventing bleeding
What is fibrin?
protein forming mesh that holds platelet plug together
What is fibrinogen?
converted into fibrin by thrombin when bleeding occurs
When is oxygen not favored by hemoglobin?
decreased pH, increased PCO2, increased temperature
What is the site of exchange between blood and tissues?
capillaries
What causes water to flow out of capillaries?
Hydrostatic Gauge Pressure and differences in osmolarity
What substance freely passes through capillaries?
Salts
What cells are able to squeeze through capillaries?
Macrophages and neutrophils
What gives plasma high osmolarity?
Albumin
What is oncotic pressure?
Osmotic Pressure provided by plasma protein
Where is hydrostatic pressure the lowest?
Near the end of a capillary
