GMS 6474 Final Exam (2024/2025) Questions with 100 % Accurate Answers || Already Graded A+ <UPDATED VERSION>
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Course
GMS 6474
Institution
GMS 6474
GMS 6474 Final Exam (2024/2025)
Questions with 100 % Accurate Answers ||
Already Graded A+
<UPDATED VERSION>
Is the symmetry in cardiac muscles the same as skeletal muscles - ANSWER no
cardiac muscles have intercalated discs and gap junctions to connect them
Do cardiac and skeletal ...
GMS 6474 Final Exam (2024/2025)
Questions with 100 % Accurate Answers ||
Already Graded A+
<UPDATED VERSION>
Is the symmetry in cardiac muscles the same as skeletal muscles - ANSWER ✔ no
cardiac muscles have intercalated discs and gap junctions to connect them
Do cardiac and skeletal muscles have the same sarcomeric structure - ANSWER
✔ yes, striated
Which kind of muscle has more mitochondria, skeletal or cardiac - ANSWER ✔
cardiac
need more ATP to keep heart beating
How do the t-tubules in cardiac muscle compare to skeletal muscle - ANSWER ✔
larger t-tubules in cardiac
form a dyad instead of triad
What controls the action of the cardiac muscle - ANSWER ✔ autonomic nervous
system
signal triggered by SA node
Importance of Ca2+ in cardiac muscle - ANSWER ✔ reliant on extracellular Ca2+
more Ca2+ means stronger contraction
the DHPR and RyR aren't physically connected like in skeletal muscles
so, needs CICR
,CICR in cardiac muscles - ANSWER ✔ calcium-induced calcium release
activated by an action potential
Ca2+ signals for RyR to open, not mechanical opening
What increases the force of contraction in the heart - ANSWER ✔ stretching it
(Frank-Starling Law)
also makes the heart more sensitive to Ca2+
possibly due to the actin and myosin being closer together when stretched
What is pre-load - ANSWER ✔ force that must be overcome before the heart
ejects blood from the ventricle during systole (contraction)
What is after-load - ANSWER ✔ force that the contraction must overcome
opposing force or arterial pressure
With high after-load, lower cardiac output
muscle can't shorten as quickly, so can't generate as much force either
what is the definiton of contractility - ANSWER ✔ change in force at a given
sarcomere length
when increased: increased velocity of ctx and strength
what are some positive ionotropes for contractility - ANSWER ✔ increase Ca2+
(open more channels, inhibit Na-Ca exchange)
what are some negative ionotropes for contractility - ANSWER ✔ decrease Ca2+
(Ca2+ channel blockers, low extracellular Ca2+, high intracellular Na+)
what is a common drug that can increase the force of contraction in the heart -
ANSWER ✔ Isoproterenol (Beta-adrenergic receptor agonist)
how does beta-adrenergic stimulation affect the heart - ANSWER ✔ stronger,
briefer, more frequent contractions
structure of smooth muscle - ANSWER ✔ electrical isolation for finer motor
control
gap junctions like in cardiac muscle
NO ACTION POTENTIAL
similar thick and thin filaments
have intermediate filaments and dense bodies (similar to z-disc)
cross bridges shorten 80% (50% more than skeletal muscle)
what are caveoli in smooth muscle cells - ANSWER ✔ invaginations in the
plasma membrane
small stores of Ca2+
contact the SR
what is the key signaling molecule in the excitation-contraction phase in smooth
muscle - ANSWER ✔ Ca2+
very similar to cardiac muscle
what is one way that Ca2+ is released in smooth muscle that is not seen in cardiac
or skeletal muscle - ANSWER ✔ pharmacomechanical coupling w/o action
potential
using IP3 and store-operated Ca2+ channels
, what is one element of the sarcomere that smooth muscle is lacking - ANSWER ✔
troponin
instead, use myosin light-chain kinase (MLCK) and calmodulin
and phosphorylation of light chains changes myosin head shape
how does smooth muscle contract - ANSWER ✔ through pharmacomechanical
coupling
no change in membrane potential
use MLCK and myosin phosphatase
Ca2+ binds to calmodulin, activates MLCK, phosphorylation changes myosin head
shape
what are the 2 types of smooth muscle contraction - ANSWER ✔ phasic
tonic
what is a phasic smooth muscle contraction - ANSWER ✔ contractions in
response to single stimuli or brief bursts of stimuli
similar to skeletal muscle contractions with Ca2+ and cross-bridge cycling
what organs use phasic smooth muscle contractions - ANSWER ✔ in muscles that
propel contents of the organ
stomach, intestines
what is a tonic smooth muscle contraction - ANSWER ✔ sustained contractions
over time
no action potentials
high Ca2+ levels that fall slowly, but maintain contraction at low Ca2+ levels
contraction thru external stimuli
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