Exam 3 Flashcards
Muscle Cell/ Muscle Fiber
A cell that has differentiated for the specialized function of contraction
Functions of the muscular system
Heat, Movement, Posture, Structure
Myofibril
The long thin contracting protein subunits of a muscle cell that are composed of actin and myosin filaments.
Thick Filament
Myosin, essentially a molecule with 2 round heads and chain-like tail.
Thin Filament
A polymer of actin with tightly bound regulatory proteins troponin and tropomyosin
function and location of myosin heads
Function: Bind and hydrolyze ATP,
Location: attached to elongated tail region
Function and location of myosin head binding sites
Function: Facilates binding so cross-bridges can form
Location: on the actin filaments
Function and location of actin
Function: Shortens the sarcomere
Location: attached at their plus ends to the Z disc
Function and location of troponin
function: sarcomeric Ca2+ regulator
location: attached to the protein tropomyosin and lies within the groove between actin filaments
Function and location of tropomyosin
Function: Stabilizes actin filaments but also regulates muscle contraction
Location: in each of the two long-pitch helical grooves of actin
Function and location of Ca2+
Function: induces skeletal muscle contraction
Location: the cytosol
Sliding filament model of contraction
Within the sarcomere, myosin slides along actin to contract the muscle fiber in a process that requires ATP.
Excitation-contraction coupling
The rapid communication between electrical events occurring in the plasma membrane of skeletal muscle fibres and Ca2+ release from the SR, which leads to contraction
Steps in the process of excitation-contraction coupling
Step 1
Action potential spread along the sarcolemma to the T-tubules (transverse tubules)
Step 2
Calcium is released into the sarcoplasmic reticulum (S.R.)
Step 3
Calcium binds to actin and the blocking action of the tropomyosin is removed
Step 4
Myosin heads attach to begin contraction
Step 5
Calcium is removed and the binding sites on actin become blocked again by tropomyosin
Step 6
Muscle relaxes
Steps in cross bridge cycling, and the involvement of ATP, cross bridges, and the myosin head ATPase
Step 1
cross bridge formation: phosphorylated myosin head attaches to an actin myofilament
Step 2
the power stroke:
1) ADP and Pi are released from the myosin head
2) Myosin head changes to bend, low-energy state
3) Shape change pulls the actin towards the M line
Step 3
cross bridge detachment: ATP attaches to myosin, breaking the cross bridge
Step 4
cocking of the myosin head: attached ADP is hydrolyzed by myosin ATPase into ADP + Pi, bringing it back to a high-energy state
How a muscle cell obtains the ATP it needs
Using creatine phosphate
Using glycogen (no oxygen)
Using aerobic respiration
isotonic Contractions
Tension remains the same in the contraction
concentric contractions
total length of the muscle shortens as tension is produced
eccentric contractions
total length of the muscle lengthens as tension is produced
isometric contractions
Length remains the same, but tension changes
main steps in hemostasis
(1) vascular spasm, or vasoconstriction, a brief and intense contraction of blood vessels; (2) formation of a platelet plug; and (3) blood clotting or coagulation
Thrombus
A blood clot that forms inside one of your veins or arteries
Embolus
An unattached mass that travels through the bloodstream and is capable of creating blockages
Universal donor
Universal donors are those with an O negative blood type.
Universal recipient
a person of blood group AB, who can in theory receive donated blood of any ABO blood group
functions of the cardiovascular system
Transport blood and O2
main parts of the cardiovascular system
heart, Arteries, veins, capillaries, and blood
the flow of blood through the parts of the cardiovascular system
Blood—-> right atrium—–> tricuspid v. —-> right ventricle——> pulmonary arteries —–> Pulmonary veins—–> heart——->left atrium—-> mitral valve——> left ventricle——> Aortic v. ——> Aorta—–> body tissues