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PHIS 206 Study Guide - Midterm Guide: Pulmonary Valve, Purkinje Fibers, Tricuspid ValvePremium

8 pages84 viewsSpring 2018

Department
Physiology and Biophysics
Course Code
PHIS 206
Professor
Charles Anderson; Steven Price
Study Guide
Midterm

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1. Valves know the valves the names, where they are, what they are between.
Atrioventricular valves
o Right → tricuspid (right AV valve) → separates right atrium and ventricle
o Left → mitral (left AV valve or bicuspid) → separate left atrium and ventricle
Semilunar valves
o Right → pulmonary valve → separates right ventricle from pulmonary artery
(lungs)
o Left → aortic valve → separated left ventricle from aorta (body)
2. What defines the two circulations?
Dual pump → right heart pumps blood from body to lungs and left heart pumps blood
from lungs to body
Both pumps must pump same amount
Right → systemic circulation to pulmonary circulation
Left → pulmonary circulation to systemic circulation
3. Which cells in the conduction system are the fastest? Next fastest? What happens if this isn’t
the case?
Conduction system: SA node → internodal pathway → AV node → bundle of His →
bundle branches → purkinje fibers → contracting muscle cells
Speed order: SA Node (70 bpm) → AV Node (50 bpm) → Purkinje fibers (30 bpm)
They are all pacemakers but the fastest sets the pace
o If the fastest one stops working, the next fastest will take the lead
o If the middle (AV node) stops working, then the atria will be controlled by the SA
node and the ventricles controlled by the purkinje fiber (2 pacemakers) → they
will be working at different rhythms and this will overwork the heart and it will
wear out faster, leads to low exercise tolerance as well
o If the purkinje fiber suddenly goes into overdrive and gets really fast, it can lead
to arrhythmia and cardiac arrest could occur (heart stops)
o Can use man made pacemakers but need to be careful around metals and magnetic
fields
4. How is BP maintained?
Baroreceptor reflex → these sensors in the arteries sense the blood pressure level and if it
is too low, the heart rate is increased. If the blood pressure is too high, the heart rate is
decreased.
This sensor does get clogged as you get older which stops it from being as sensitive
You need enough pressure in your system at all times for adequate flow
5. What are the purposes of the different vessel types?
Heart → pumps blood
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Arteries → withstand high pressure, tough coat, smooth muscle so can stretch to
accommodate blood pumped out with each heartbeat, ability to stretch keeps reasonable
pressure (recoils after stretch)
Arteriole → regulate flow
Capillaries → exchange (waste like CO2 and oxygen), composed of just endothelium
(very thin, thinnest)
Veins → reservoir and one-way flow, have valves to prevent backflow, most of blood is
in veins at any given time
6. To what is flow rate proportional? Inversely proportional?
Change in pressure is proportional to change in flow (change in pressure causes change in
flow)
Resistance goes up, flow goes down → inversely proportional
Larger tube, higher flow (proportional)
When radius decreases, flow decreases (because resistance increases)
When radius increases, flow increases (because resistance decreases)
Therefore, I believe flow is proportional to radius
7. Why is there a parallel distribution of blood?
Everyone receives fresh blood, cardiac output is divided between organs and tissue beds
in a parallel fashion
Parallel arrangement → no one gets used blood because everyone gets fresh blood
(exception: liver)
8. What is located in each of the components of blood?
Erythrocytes (about 45%) - red blood cells
Buffy coat (less than 1%) - platelets and leukocytes
Plasma (about 55%) - proteins and electrolytes
9. How is cardiac output divided at rest? During exercise?
Cardiac output during rest: less than during exercise
During exercise, same amount goes to brain, more goes to skeletal muscles
Capillary beds are perfused (supplied) when demand exists (like during exercise?)
10. How are the phases of the cardiac cycle defined?
Systole - contraction part of cardiac cycle
Diastole - relaxation part of cardiac cycle
P QRS T?
P = atrial depolarization
QRS = ventricular depolarization
T = ventricular repolarization
11. What is the process of erythropoiesis?
Erythropoiesis = what the differentiation process is known as
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Kidney plays major role in triggering/regulating erythropoiesis
Hormone: erythropoietin released by kidney → stimulated stem cells to differentiate
Pluripotent stem cell → myeloid stem cell → erythroblast (has nucleus and organelles)→
reticulocyte (has remnants of organelles) → erythrocyte (no nucleus or organelles)
1. Reduced oxygen carrying capacity (less red blood cells)
2. Kidney releases erythropoietin because less O2 is delivered to kidneys
3. Erythropoietin stimulates erythropoiesis in red bone marrow
4. Now additional erythrocytes in so O2 carrying capacity is increases
5. Initial stimulus for erythropoietin is stopped because no longer O2 deficient
12. Valve trouble what types?
Opening problems → stenosis (does not open all the way)
Closing problems → regurgitation or insufficiency
Murmur in heartbeat → valve not working correctly
Mouth bacteria infect heart valves (bacterial vegetation) → can lead to blood clot in heart
→ heart attack?
13. How and why do vessels vasoact?
How:
o Vasoconstriction = narrowed vessel
o Vasodilation = widened vessel
o Must have substantial smooth muscle layer to vasoact (capillaries can’t, veins
can’t do it well, best in arteries)
Why:
o When you need blood → vasodilation (low oxygen, high levels of waste, low
myogenic activity, high nitric oxide, low sympathetic stimulation)
o When you’re well-nourished → vasoconstriction (high myogenic activity, high
oxygen levels, low wastes, high endothelin, high sympathetic stimulation)
14. What provides the resistance to flow?
Length of vessel, thickness of fluid
Greatest impact: radius of vessel
When radius decreases, resistance increases and flow decreases
Basically, radius is proportional to flow because it is inversely proportional to resistance
Bigger radius, less resistance, more flow
Bigger the tube, bigger the flow
15. Anemia, Polycythemia, Normal Hct, et cetera.
Anemia (~30% hematocrit) - low levels of red blood cells which means thinner blood,
reduced ability to carry oxygen
Polycythemia (~70% hematocrit) - too much red blood cells which means thicker blood,
more difficult pumping
Normal (~45% hematocrit) - regular
Dehydration (~70% hematocrit) - thicker, same blood level but less plasma, similar to
anemia but reversed I would say
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