Lecture 5 Flashcards
General Principles of Skeletal, Cardiac & Smooth Muscle
name the three types of muscles?
skeletal muscle, smooth muscle, and cardiac muscle
which muscle of the three named acts on the skeleton, is it voluntary or involuntary?
skeletal muscle; voluntary
what is skeletal muscle responsible for?
it plays a key role in posture, locomotion, speech, and respiration
what kind of striations are found in skeletal muscle?
it exhibits transverse striations (2-3 micrometers) that result from the highly organized arrangement of actin and myosin molecules
skeletal muscle is striated or non striated?
striated
what kind of muscle is the heart? voluntary or involuntary?
its composed of cardiac muscle; involuntary
what controls the heart?
controlled by an intrinsic pacemaker and modulated by the autonomic nervous system
striations are found in the smooth muscle, T/F?
False
smooth muscle is voluntary or involuntary? where is it found?
involuntary; found lining the hollow organs such as the intestine and blood vessels
what is it called when each skeletal muscle fiber contains bundles of filaments? where are these found
myofibrils; running along the axis of the cell and so this pattern results from repeating pattern in the myofibrils
what comprises the tropomyosin molecule?
consists of two identical alpha helices that coil around each other and sit near the two grooves formed by two helical actin strands
what comprises the troponin molecule?
a heterotrimer consisting of troponin T, C, and I
what is troponin T?
this binds to a single molecule of tropomyosin
what is troponin C?
this binds Ca2+
what is troponin I?
this binds to actin and inhibits contraction
how does the muscle work in the contracted state?
a ratchet action of myosin which pulls actin toward the center of the sarcomere
what is the function of the heart?
pumps blood through the circulatory system accomplished by the highly organized contraction of cardiac muscle cells
what do muscle cells form when they are connected together?
electrical syncytium through electrical and mechanical connections between adjacent cardiac muscle cells
how does the action potential pass through the heart?
because the heart is arranged in way that forms an electrical syncytium via gap junctions, an action potential is therefore able to pass quickly throughout the heart to facilitate synchronized contraction of the cardiac muscle cells important for the pumping of the heart; ultimately refilling of the heart requires synchronized relaxation of the heart
cardiac muscle are larger or smaller than skeletal cells?
cardiac muscle cells are smaller and measure 10 micrometers in diameter by 100 micrometers in length
what are the connections between cardiac cells called?
intercalated disks
what are intercalated disks?
a combination of mechanical junctions and electrical connections
why are the mechanical connections in the heart important?
these are the fascia adherent and desmosomes and these keep the cells from pulling apart when contracting
gap junctions are electrical connections or mechanical connections in the heart?
these are between the heart cells and provide electrical connections between cells to allow propagation of the action potential throughout the heart
how do the connections in the heart facilitate the movement of a single action potential within the heart?
the action potential is generated within the SA node to pass thoughout the heart so that the heart can contract in a synchronous wave like fashion
what ion is responsible for the initiation of the action potential?
calcium
there is more connective tissue in the skeletal muscle than cardiac tissue?
more in the heart
what is the reason for having more connective tissue in the heart?
it helps prevent muscle rupture like in skeletal muscle but also prevents the overstretching of the heart