BIOL 252 EXAM 1 BUNDLED TESTS SCRIPT
TESTED QUESTIONS AND CORRECT
SOLUTIONS VIEW AHEAD PREP UPDATED
⩥ Cardiac output (CO).
Answer: how well our hear muscle functions; amount of blood
ejected from the left ventricle into the aorta in one minute
• CO = stroke volume x heart rate
• entire blood supply passes through the heart once every minute
• CO varies with demands of the body
⩥ heart rate.
Answer: number of heart beats/minute
⩥ cardiac reserve.
Answer: difference between maximum cardiac output and
resting cardiac output
• a well-trained endurance athlete may have a cardiac reserve of
35 L/min or 600% of normal
,⩥ so how can we change our cardiac output so dramatically?
(the heart as a paradigm for homeostasis).
Answer: we can increase SV by either increasing EDV (blood
entering the ventricle) or decreasing ESV (blood left in the
ventricle)
⩥ 3 ways to regulate SV.
Answer: - preload
- contractility
- afterload
⩥ preload.
Answer: the amount of tension of the ventricular muscle prior to
its contraction; the amount of tension of the ventricular muscle
before it contracts
• adding more blood to the heart, stretching the resting fibers
more leading to a stronger contraction which expels more blood
→ Increases SV
• INtrinsic regulation (the cardiac system regulates preload)
⩥ Increased EDV =.
,Answer: Increased Preload (and as a result decreased ESV and
increased SV)
⩥ Frank-Starling's Law of the heart.
Answer: the more stretched the resting fibers, the more forceful
the contraction
⩥ Increased Venous return.
Answer: increased ventricular filling → increased preload →
increased ventricular stretch (Frank-Starling mechanism) →
increased force of contraction (DECREASING levels of ESV)
→ increased cardiac output
⩥ contractility.
Answer: the amount of force produced during a contraction, at a
given preload
• INCREASES SV
⩥ which system regulates contractility?.
Answer: - mainly the nervous system (Sympathetic nervous
system of the ANS [NE]; shorter response)
, - supplemented by the endocrine system causes contractility (the
adrenal medulla secretes Epi and NE; longer response) →
EXtrinsic regulation
⩥ mechanisms of regulating contractility.
Answer: - main mechanism → open more Ca channels on the
membrane itself of the cardiac muscle, increase of intracellular
Ca, more myosin-actin interactions, stronger contraction
- increases blood flow, causing preload and heart to contract
more forcefully
- increase frequency of APs from the SympNS which causes
more release of Ca and more myosin binding
⩥ what would make the cardiocytes contract more strongly?.
Answer: aerobic conditioning exercise
⩥ afterload.
Answer: the pressure that the ventricle has to overcome to force
open the semilunar valves; DECREASES SV
• results from the blood pressure in the aorta (how "strong" the
backflow pushes the valves [closed in this case])
TESTED QUESTIONS AND CORRECT
SOLUTIONS VIEW AHEAD PREP UPDATED
⩥ Cardiac output (CO).
Answer: how well our hear muscle functions; amount of blood
ejected from the left ventricle into the aorta in one minute
• CO = stroke volume x heart rate
• entire blood supply passes through the heart once every minute
• CO varies with demands of the body
⩥ heart rate.
Answer: number of heart beats/minute
⩥ cardiac reserve.
Answer: difference between maximum cardiac output and
resting cardiac output
• a well-trained endurance athlete may have a cardiac reserve of
35 L/min or 600% of normal
,⩥ so how can we change our cardiac output so dramatically?
(the heart as a paradigm for homeostasis).
Answer: we can increase SV by either increasing EDV (blood
entering the ventricle) or decreasing ESV (blood left in the
ventricle)
⩥ 3 ways to regulate SV.
Answer: - preload
- contractility
- afterload
⩥ preload.
Answer: the amount of tension of the ventricular muscle prior to
its contraction; the amount of tension of the ventricular muscle
before it contracts
• adding more blood to the heart, stretching the resting fibers
more leading to a stronger contraction which expels more blood
→ Increases SV
• INtrinsic regulation (the cardiac system regulates preload)
⩥ Increased EDV =.
,Answer: Increased Preload (and as a result decreased ESV and
increased SV)
⩥ Frank-Starling's Law of the heart.
Answer: the more stretched the resting fibers, the more forceful
the contraction
⩥ Increased Venous return.
Answer: increased ventricular filling → increased preload →
increased ventricular stretch (Frank-Starling mechanism) →
increased force of contraction (DECREASING levels of ESV)
→ increased cardiac output
⩥ contractility.
Answer: the amount of force produced during a contraction, at a
given preload
• INCREASES SV
⩥ which system regulates contractility?.
Answer: - mainly the nervous system (Sympathetic nervous
system of the ANS [NE]; shorter response)
, - supplemented by the endocrine system causes contractility (the
adrenal medulla secretes Epi and NE; longer response) →
EXtrinsic regulation
⩥ mechanisms of regulating contractility.
Answer: - main mechanism → open more Ca channels on the
membrane itself of the cardiac muscle, increase of intracellular
Ca, more myosin-actin interactions, stronger contraction
- increases blood flow, causing preload and heart to contract
more forcefully
- increase frequency of APs from the SympNS which causes
more release of Ca and more myosin binding
⩥ what would make the cardiocytes contract more strongly?.
Answer: aerobic conditioning exercise
⩥ afterload.
Answer: the pressure that the ventricle has to overcome to force
open the semilunar valves; DECREASES SV
• results from the blood pressure in the aorta (how "strong" the
backflow pushes the valves [closed in this case])
