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Final

BPK 205 Study Guide - Final Guide: Voltage-Gated Potassium Channel, Mitral Valve, Superior Vena Cava


Department
Biomedical Physio & Kines
Course Code
BPK 205
Professor
Parveen Bawa
Study Guide
Final

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Chapter 14
1.What purpose does the cardiovascular system serve?
Deliver oxygen and nutrients and remove waste
2. Draw the heart and label its atria, ventricles, two nodes, valves, arteries, and veins.
3. Why does blood flow? Why does blood flow faster through smaller vessels?
All fluids flow down pressure gradients. From high pressure to low pressure. There is
high pressure created in heart chambers during contraction, and lower pressure in blood
vessels. Lowest pressure is at the Vena cava just before blood enters the right atrium.
Blood flow is faster through smaller vessels because Flow Velocity = Flow rate/Cross-
sectional Area. A smaller vessel will have a smaller Cross-sectional area, and since Flow
velocity is inversely proportional to Cross-sectional are, then the Flow Velocity will be
greater.

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4. Explain the similarities and differences between cardiac, smooth, and skeletal muscle.
Skeletal:
oStriated (fibers are parallel)
oHave Sacromeres
oNeed motoneuron for excitation
oNeed APs
oCa++ for contraction targets thin filaments
oHave T-tubules
Smooth:
oNot Striated
oNo sacromeres
oCan be autorythm or excited by neurotransmitters
oMay or may not have APs
oCa++ for contraction targets thick filaments
oOther facts:
Hormones and Paracrines
Maintains force over longer period of time. In many organs, it’s
even tonic. Ex. Sphincter of bladder
No T-tubules
Instead of z-lines, it has dense bodies or protein plaques (the
latter attaches it to cell membrane)
Cardiac:
oStriated
oHave sacromeres
oNeed depolarization from autorythmic cardiac cells for excitation
oHave APs
oCa++ for contraction targets thin filaments
oHave T-tubules, but they’re larger than in skeletal muscle
Depolarization of cell from an adjacent cell activates voltage gated
Ca++ channels for Ca++ intake.
Release of Ca++ from SR is initiated by incoming Ca++ from
outside the cell, not by depolarization of T-tubule
oHave Intercalated disks that contain demosomes that transfer force
between cells
oGap junctions transfer electrical activity between cells
5. How do autorhythmic cells generate their rhythm (mentions channels/currents)?

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SA node composed of nodal tissue that has characteristics of both muscle and
nervous tissue
SA node generates impulses that travel through the heart causing both atria to
contract
When impulses reach the AV node, there is about a tenth of a second delay from
when it started in the SA node. This allows the atria to empty blood into the
ventricles. Ventricles contract when impulses reach AV node.
Impulse travels down to the atrioventricular bundle, and branches down to the
base of the heart where they divide into the purkinje fibers. These purkinje fibers
contract
Refractory period much longer than in skeletal muscle fibers. This is to avoid
tetanus
The HCN channels that slowly activate control pacemaker potential and, the
rhythm.
1. Hyperpolarization of autorythmic cells activates HCN gated channels
(gated by either cAMP or cGMP). Channel open to K+ and Na+.
2. More Na+ flows in than K+ flows out slowly causing depolarization. This
starts the pacemaker potential
3. Eventually threshold for voltage gated L-type Ca++ channels is reached.
Ca++ flows in starting the action potential depolarization
4. At maximum depolarization, voltage gated K+ channels open, and Ca++
channels close, causing repolarization to occur.
6. Describe the Cardiac cycle including the conduction of electrical signals within the
heart and the contraction/relaxation of the muscles. How do these events relate to the
PQRST waves measured using ECG? [ I do not want the pressure-volume diagram or the
Wiggers diagram here--want just the sequence of events including depolarizations,
contractions,opening or closing or valves]
When does the atrium go through diastole, and when is the ventricle in diastolic
condition?
1. Blood passively flows from inferior and superior vena cava to right atrium
2. SA node pulses causing both atria to contract. Tricuspid Atrio-ventriocular valve
opens allowing blood to flow into the right ventricle
3. Tricuspid valve closes blocking backflow
4. Impulse reaches to AV node, depolarizing it which causes ventricles to contract.
Pulmonary semilunar valve opens allowing blood transfer via pulmonary arteries
to the lungs. When pressure in Pulmonary arteries is greater than pressure in the
right ventricle, then the valve will close to prevent backflow
5. Blood returns to heart via pulmonary veins. Blood enters left atrium passively.
6. Another impulse begins at SA node to contract atria. Blood enters left ventricle
via bicuspid valve. Once blood pressure is greater in left ventricle than left atrium,
the bicuspid valve shuts
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