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level: Muscles

Questions and Answers List

level questions: Muscles

QuestionAnswer
Contract and relax to cause movementSkeletal muscles
What are cells in skeletal muscles and describe:Muscle fibers:long, cylindrical
Nuclei in skeletal musclesMany: peripheral (cell’s edges)
striated musclesSkeletal, Cardiac
Can see visible lines on muscles (dark/light)striated
Dark and light (striated) lines caused by:Actin and myosin
Actin and myosin are proteins responsible forMuscle contraction
Are skeletal muscles controlled by voluntary or involuntary movement?Voluntary
Line hollow organs, allow substances to move through organs by squeezingsmooth muscle
Nucleus in smooth muscle cells (how many and where?)One, centrally locates
Are smooth muscles striated?No
Are smooth muscles controlled by voluntary or involuntary?Involuntary
Only found in walls of the heart (makes up the heart)Cardiac muscle
Is cardiac muscle striated?Yes
Are cardiac cells branched?Yes
Are skeletal cells branched?No
Cardiac cells are joined together at unique junctions called:Intercalated discs
How many/ where are(is) nucleus in cardiac cellsOne in the center
Are cardiac muscles controlled by voluntary or involuntary movement?Involuntary
Can INdirectly increase heart rate, but not directly-the ability to receive and respond to stimuliCardiac muscles
Muscles have a chemical stimulus (ex:hormone) ; the response is an electrical impulse that causes the muscle to respond (contract, etc.)Excitability/Responsiveness
Ability to contractContractility
ExtensibilityAbility to stretch farther
Ability to return to original size without being changedElasticity
Functions of muscles:Produce movement
Muscles maintaining posture vs bonesBones are framework/structure, but muscles keep you upright and fight gravity
Structures that allow or prevent substances going through or in and out, by opening and closingValves
Connective tissue covering over entire muscle, is found on all musclesEpimysium
Connective tissue, attaches muscle to boneTendons
When a person dies, their body no longer produces ATP, so actin and myosin stay locked together, and muscles stiffen (reverses after 48 hrs as muscle proteins break downRigor mortis
Flow of ions through biological tissue creates electrical currents which act as signalsElectrophysiology
Plasma membranes of muscle cells have:Resting membrane potential
Charge when muscles aren’t contractingResting membrane potential
Cells have a differing concentration of ions on either side of cell membrane because:Cells are selectively permeable
Let certain things in or outSelectively permeable
Resting membrane potential in most cells-70 mv
Because there’s a lot of sodium outside the cell, and potassium inside the cell, there’s an uneven distribution of ions across the membrane, causing the membrane charge: the inside of the cell has a negative charge COMPARED to the outsideMembrane potential
the electrical impulse system/cycle:the local voltage change across the cell wall as a nerve impulse is transmittedAction potential
Many action potential cycles together causethe muscle to contract
First step of action potentialAcetylcholine
Bonds to receptor in muscle cell, signals itAcetylcholine
Second step of action potentialSodium (Na+) rushes into cell through Na+ channels (because of concentration gradient), so the charge in the membrane becomes more and more positive
Third step of action potentialThe second step happens until cell reaches the charge needed for an electrical impulse
Charge needed for an electrical impulseThreshold
Fourth step of action potentialOnce the threshold is reached, potassium stops coming: potassium(K+) leaves the cell through K+ channels. As it leaves, the charge of the cell returns to regular (resting membrane potential)
Fifth step of action potentialSodium goes back out of cell/potassium comes back in , through the Na+/K+ Pump (which is constantly active)
How many sodium’s are pumped out in step 5 for every 2 potassium’s pumped in?3s out: 2P in
The action potential electric current is needed for:Actin/myosin to function