Ch. 14 + 16 Part 1 - Respiratory Physiology Flashcards
Define cardiac output (CO)
volume of blood pumped each minute by each ventricle
Define end-systolic volume (ESV)
volume of blood in the ventricles at the end of contraction
(volume is NEVER zero, is the lowest volume of blood in the ventricle at any point in the cardiac cycle; about 40% remains in ventricles after a contraction)
What describes the lowest volume of blood in the ventricle at any point in the cardiac cycle?
ESV (end systolic volume)
Define end diastolic volume (EDV)
volume of blood in the ventricles at the end of filling
(about 60% of EDV is ejected)
Define stroke volume (SV)
volume of blood ejected from the ventricles per beat (due to the contraction of the heart muscle); increases with increase contractility
(ex: if # of beats increase, SV will increase too)
What is the equation of cardiac output?
CO (ml/min) = SV (ml/beat) x HR (beats/min)
What are 4 factors that can affect HR?
What factor affects SV?
HR: ANS, hormones (ex: epi), fitness levels, age
SV: contractility
What is the average HR, SV, and CO?
HR = 70 bpm
SV= 70-80 ml/beat
CO = 5,500 ml/minute
CO of the left ventricle must ______ the output of the ________ ventricle so that the blood flow through both the __________ and __________ circuits are equal
equal
right
pulmonary
systemic
What is the eq for stroke volume (SV)?
SV = EDV - ESV
Define CO, ESV, EDV, SV. How are all of these related?
CO = SV x HR = (EDV-ESV) x HR
TRUE or FALSE: ESV is greater than EDV
False, ESV is the lowest volume of blood in the ventricle at any point in the cardiac cycle
What substance(s) function in keeping HCN channels open longer at the SA node? Is this controlled by SANS or PANS?
- norepinephrine
- epinephrine
- SANS (sympathetic)
What substance(s) function in opening K+ channels at the SA node? Is this controlled by SANS or PANS
- ACh
- PANS (parasympathetic)
Name the NTs involved in the sympathetic effect vs parasympathetic effect on the heart.
Explain how they carry out their effect on the heart
Sympathetic: norepinephrine and epinephrine -> keep HCN channels open -> PP slow increases -> increase HR
Parasympathetic: ACh -> open K+ channels -> PP slow to increase (less steep) -> decrease AP frequency -> decrease Ca2+ release -> decrease contractility and CO -> decrease HR
How does the SA node AP graph change under the influence of the sympathetic autonomic nervous system and why? (hint: what happens to PP?)
SA node AP graph will change in frequency (more AP produced)
SANS can release epinephrine which will produce cAMP. HCN channels are sensitive to cAMP and will stay open longer, causing more Na+ influx. This will increase/steepen the slope of the PP
Why would epinephrine increase heart rate (HR) and how does this happen?
Epinephrine increases heart rate because it produces cAMP which keeps HCN channels open longer
Sympathetic = epinephrine = ↑ cAMP = HCN channel stays open longer = Increase/steep slope of Pacemaker Potential = ↑ frequency of APs = ↑Ca2+ release from SR (of myocardial cells; nonspecialized) = ↑ # of contraction and CO = ↑HR
How does the SA node AP graph change under the influence of the parasympathetic autonomic nervous system and why? (hint- what happens to PP)
Parasympathetic = ACh = open K+ channel = ↓slope of PP = ↓frequency of APs = ↓ # of contraction and CO= ↓ HR
This is because ACh has an inhibitory effect on the SA node
Define hemoglobin (Hb) and how is it related to O2?
Hemoglobin: A complex protein (containing heme molecule; iron, and globin protein) that contains 4 subunits found in RBC
It is related to O2 as each of its subunits carries one O2 from the lungs to the rest of the body (each Hb can bind to 4 O2 molecules)
What is total O2 content dependent on?
PO2 and Hb concentration
PO2 is directly proportional to…
the amount of O2 availiable (PO2 measures O2 concentration)
What is another name for Hb-O2?
oxyhemoglobin
What is another name for Hb?
deoxyhemoglobin
What is another name for Hb-CO2
Carbaminohemoglobin
What is another name for Hb-CO
Carboxyhemoglobin
Define oxyhemoglobin
Hb-O2
Hb is bound to O2
Define deoxyhemoglobin
Hb
When O2 is released (unloaded) to the tissues