Bolded Exam #1 Flashcards
functional contracting unit of the muscle fiber
sarcomere
thick filament on muscle filament
myosin
thin filament on muscle filament
actin, tropomyosin, troponin
filamentous protein that runs along the groove of each twisted actin filament - function is to block the myosin-binding sites on actin
tropomyosin - must be moved out of the way during contraction so that myosin can bind to actin
A complex of 3 globular proteins located at regular intervals along the tropomyosin filaments
troponin - T, I, C
attaches the troponin to tropomyosin
troponin T
along with tropomyosin inhibits the interaction of actin and myosin by covering myosin-binding site of actin
troponin I
is a Ca2+ binding protein that plays central role in the initiation of contraction
troponin C - binds to troponin C and then alters shape to remove tropomyosin from the myosin binding sites
As long as intracellular Ca2+ is _______ cross-bridge cycling cannot occur and the muscle relaxes
LOW
What is it called when intracellular Ca2+ concentration never returns to the low levels that exist during relaxation? Results in continued binding of Ca2+ to troponin C
Tetanus - occurs when muscle is continually stimulated and there is insufficient time for the SR to re-accumulate Ca2+
ICF calcium remains high
hypertrophy causes what in the muscle? what causes it?
increase in actin and myosin
caused by near maximal force development (weight lifting)
myofibrils split
formation of new muscle fibers is called what? what causes it?
hyperplasia
-caused by endurance training, but this is rare occurrence otherwise?
lengthening of the muscle is normal and causes what?
increased shortening capacity, and increased contraction velocity
- this occurs with normal growth
- no change in force development?
smooth muscle contains both ______ and _____ filaments, but does not have ______
how does smooth muscle contraction happen and what is it called?
myosin and actin
- does NOT have troponin
- contractile process activated by Ca2+ ions and ATP that is broken down to ADP
pull in opposite directions of actin filaments - this allows smooth muscle to contract about 80% of its length vs 30% in skeletal muscle
-this is called side polar cross-bridge
The 2 major neurotransmitters of smooth muscle?
norepinephrine and ACh
- both excitatory and inhibitory
- when ACh excites a muscle fiber, norepinephrine ordinarily inhibits it;
conversely when norepi excite ACh normally inhibits
*really it’s the type of receptor that these bind to as to whether it’s an excitatory or inhibitory signal
Since there is no troponin in smooth muscle, how does myosin interact with actin?
The interaction of myosin and actin is controlled by binding of Ca2+ to a protein called calmodulin
negative feedback is what and promotes what?
- negative feedback returns body to normal/homeostasis
- cancels out the original response
- ex. when blood sugar spikes and insulin restores normal blood sugar levels
- negative feedback promotes STABILITY
positive feedback is what and promotes what?
- exaggeration or more of the original response
- may be unstable or normal
- promotes instability/disease BUT can be normal
- normal ex: oxytocin release during childbirth stimulates labor contractions; platelets and clotting cascade
proteins in the cell membrane provide _____
selectivity with integral (throughout membrane) and peripheral (on one side) - can act as enzymes, receptors, channels
*provide SELECTIVITY to a membrane
cholesterol in the plasma membrane generally decreases _____ and _____ but increases membrane ____ and ______
Decreases fluidity and permeability, but increases membrane flexibility and stability
ATP is converted to ____ to produce energy. What bonds are broken to produce this energy?
adenosine triphosphate - chemical bonds b/w the 2nd and 3rd phosphate groups contain abundant energy and the rupture of the terminal phosphate bond produces energy
Simple/passive diffusion
Why does this movement occur?
Remember that diffusion will not occur if?
ion moves from higher concentration to lower concentration down concentration gradient
- the movement is to equalize the charge across the membrane
- diffusion will not occur if the membrane is non-permeable to the molecule
3 factors that influence diffusion?
concentration difference, electrical potential (EMF), and pressure difference
osmosis
passive transport of fluid across a membrane from an area of lower solute concentration to an area of higher solute concentration
Primary active transport
uses energy to move ions across the membrane - ex Na/K/ATPase pump (carrier protein)
-uses energy b/c ions are pumped against (uphill) against concentration gradient
secondary active transport
transport driven by the energy stored in the concentration gradient of another molecule (Na+) - this is considered the driver molecule
-indirect use of energy
The Na/K/ATPase pump plays an important role in
Where are Na/K pumped and how many ions?
regulating osmotic balance by maintaining the Na/K balance so the cell does not swell and burst
- 3 Na+ pumped out, 2 K+ pumped in
- also important in establishing resting membrane potential
What is the function of Ca2+ ATPase? Where is this transport protein found?
keeps ICF calcium low (maintains a low cytosolic Ca2+ concentration)
-found in the cell membrane of the sarcoplasmic reticulum - remember the SR is considered ECF
What is the function of H+ ATPase? Where is it found?
- found in the parietal cells of gastric glands (HCl secretion) and intercalated cells of renal tubules (CONTROLS BLOOD pH)
- concentrates H+ ions up to 1 million-fold
type of tissue - a continuous cellular sheet that covers body’s surfaces, lines body cavities, forms certain glands
epithelial tissue
type of tissue - binds together and supports body structures. What does it include?
connective tissue - includes bones, cartilage, and adipose (fatty) tissue
type of tissue - has a generous blood supply, and movement and contraction is the main purpose
muscle tissue
nervous tissue - main function? properties?
main function is communication
primary properties are irritability and conductivity
decrease in cell size
atrophy
increase in cell size. examples pathological and physiological?
hypertrophy
- physiological d/t wt lifting
- pathological growth in cardiac m. size d/t HTN