Coronary Circulation/Temp Regulation Flashcards
What period of cardiac cycle has coronary blood flow in the L ventricle the lowest
isovolumertric contraction
Why is coronary perfusion of the left ventricular myocardium is low during systolic periods and higher during diastolic periods
this is an effect of the pressure gradient, since the aortic pressure is highest in diastole
What is the effect of cardiac dilation of ventricular wall tension and mycoardial perfusion
larger the ventricle, higher the tension and myocardial perfusion is reduced
Most frequent location of MI
subendocardial arterial plexus
Why is subendocardial arterial plexus most senstivie to compressive forces and damage
due to variation in perfusion during cardiac cycle
Effect of increased heart rate on mycocardial perfusion
increase HR results in increased perfusion because the pressure is higher in CBF, and the demand of O2 from the heart would be higher
Sublingual body temp
approximately normal - 37 C
rectal temp
closer to actual core temp - 36.1 to 37.8 C
axillary temp
about 1 F less than oral
3 causes for normal variation in body temp
diurnal variability
estrous cycle
exercise
How does diurnal variablity affect normal body temp
lower in morning, higher in evening
How does estrous cycle affect normal body temp
luteal phase elicits an abrupt increase in temperature
How does exercise affect normal body temp
metabolic rate
Core temperature
temp inside the thoracic, abdominal, and brain/spinal cord
Shell temperature
skin
Radation
heart leaves/enters the body when it’s colder/warmer outside
Condition
heart flows down thermal gradient with DIRECT contact
Evaporation
sweat evaporates from our skin, takes heat with it
Convection
heart dissipated by current/movement (air/water)
What does cutatneous/core thermoreceptors do when temp rises
activates sweating and cutaneous vasodilation
What does cutaneous/core thermoreceptors do when temp drops
initiates shivering, cutaneous vasoconstrction, inhibits sweating
What changes in the body when temp increase
vasodilation, sweating
shivering, thermogenesis and piloerection inhibited
What changes in the body when temp decreases
vasconstrction, shivering, thermogenesis, pilorection
What does epinephrine do when body temp decreases
increase thermogensis
What does NE do when the body temp decreases
cutaneous vasoconstriction
How do vasodilation and sweating get inhibited
PANS innervation results in the hypothalamus releasing TRH, which causes anterior pititarty to release TSH, which causes thyroid gland to release thyoxine which increases metabolitic thermogensis
