Quiz Info Exam 2 Prep Flashcards
Role of sacroplasmic reticulum ca2+ ATPase (SERCA)
As soon as calcium flows into sarcoplasm from SR, SERCA begins pumping calcium back into SR against gradient
What leads to stop in muscle contraction and muscle relaxation
SERCA
A bundle of muscle fascicles
Whole muscle
Intracellular storehouse of calcium ions
SR
Contracting subunits that make up each myofibril
Sacromeres
A bundle of muscle fibers
Muscle fascicle
Contractile assembly of proteins in a muscle cell
Myofibirl
In the presynaptic terminal of a neuromuscular junction there’s what…
Somatic motor neuron, clusters of synaptic end bulbs, contains ach
Which property was of slow twitch muscles exceeds the performance of fast twitch muscles
Endurance
Slow myosin ATPase is better for
Endurance exercise, for long periods of time
Slow twitch muscles have what diameter
Small
Do slow twitch or fast twitch muscles stores more glycogen
Fast twitch
Structural feature of sacromere that serves as an anchor to actin thin filament or edges of sacromere
Z line or disc
Which factor determines the amount of tension generated by a single motor unit
Number of muscle fibers that have synapses with the motor neuron
Each motor unit has how many motor neurons
1
To counter the perceived length change reported by muscle spindles, the quad…
Activated to contract
Reflex actions don’t require
Higher centers of motor control
What membrane protein facilitates muscle relaxation by returning calcium into SR
Ca ATPase
Calcium release channel
RyR
Open flow occurs down calcium concentration gradient, calcium flowing out of SR through which membrane protein
RyR
Facilitates muscle activation by opening the calcium release channel
DHP membrane protein
is the DHPR involved in muscle relaxation
No
What causes the detachment of myosin from actin at the end of the cross-bridge power stroke
Binding atp
Without conformational change that atp binding causes myosin would
Remain tightly associated with actin (rigor mortis)
If myosin has atp in its nucleotide binding site it
Hydrolysis it
If an attached myosin bound, then released ATP its affinity’s from actin would be
Strong and reattach firmly
What description best describes the isotonic twitches measured during the muscle lab by stimulating the subjects motor point
The time to reach the peak of the twitch was shorter than time to return to rest position (activation faster than relaxation)
What event is triggered by the binding of ach to its receptor on a skeletal muscle cell at the neuromuscular junction
EPP
Binding of acetylcholine to its receptor opens the
Ligand gated channel to cause an EPP
Ach binding is or is not a direct cause of calcium release
Is not
Action potentials require
VG Na channels
Network of connecting passages that conduct action potential through a muscle cell
T tubules
Extension of the plasma membrane
T tubules
Network of passages but doesn’t run from the sarcolemma through entire cell
SR
Gap junctions only found in
Cardiac muscles
What factor determines the duration of the latent period for an isotonic contraction
The load the muscle is working to move
Heavier load=
Longer it takes to generate force
Additional time when generating enough force to move a heavy load is the
Latent period
Muscle action potentials __ in amplitude
Don’t vary
Skeletal muscle doesn’t use what during its contractions
EC calcium
In a contractile myocyte, the lengthening of the cardiac sarcomere corresponds to which ONE of the following?
Ventricular diastole
Consider the direction of DE-polarization versus the direction of RE-polarization of the left ventricular muscle. What does this mean for the cells of the endocardium (inside heart muscle) compared to the epicardium (outside heart muscle)?
Cells in the endocardium are first to depolarize and last to re polarize
Autorhythmic activity of pacemaker cells can be modulated by:
Atrial DE-polarization
Rapid RE-polarization by voltage-gated K+ channels
The unstable resting potential due to the F-type channel by the autonomic nervous system
The unstable resting potential due to the F-type channel by the autonomic nervous system
The “funny” current or channel has an unstable resting membran potential and can be modulated by the
ANS
Which ONE of the following is TRUE regarding calcium-induced calcium release (CICR)?
A. The Na+/Ca2+ exchanger (NCX) returns Ca2+ to the sarcoplasmic reticulum
B. Ca2+ from the sarcoplasmic reticulum is released into the cytoplasm by the ryanodine receptor
C. DE-polarization of the sarcolemma activates voltage-gated dihydropyridine receptors to prevent Ca2+ release
B
Consider electrical conduction in the heart. Which ONE of the following is TRUE?
A. There are fewer pacemaker cells in the SA node compared to the AV node
B. Conduction slows down in the intermodal pathways of the atria
C. The AV node is the slowest to conduct because it has the fewest gap junctions
C
Av nodal delay is shown between
P wave and QRS complex
With respect to the mean ventricular axis (MVA), lead II of the ECG:
is most parallel to the direction of depolarization
can “see” the greatest changes in electrical activity of the heart with what lead
2
Consider the cardiac action potential. Which ONE of the following is TRUE about the plateau phase?
A. Tetany occurs during the plateau phase
B. Another stimulus can cause it to increase force
C. It allows for the completion of contraction and relaxation
C
During ventricular systole what valves are open
Pulmonary and aortic valves
During ventricular diastole what valves are open
Av valves
Which part of the cardiac cycle best represents preload?
Isovolumetric contraction
Greater preload means
Greater stroke volume
Afterload combines what two concepts
EDV and arterial pressure during ventricular systole
Relationship between afterload and velocity of shortening
Greater afterload, Slower velocity of shortening
What is hypertension in means of blood pressure and afterload
Increased afterload, increased BP
Relationship between pressure and velocity of shortening
Increased pressure=decreased velocity of shortening/slower velocity= increased afterload
What process has the smallest number of ATP and is reversible
Creatine kinase
At rest vs at contraction what is the relationship of ATP and ADP in relation to creatine kinase
Rest= increased atp, decreased adp
Contraction= decreased atp, increased adp
The structure of a muscle spindle is
Encapsulated within muscle
Structure of golgi tendon
Isolated in tendon
The regions of the middle level of motor control perform what functions
Involuntary
Brainstem is in the
Middle level of motor control
Higher level centers in the motor control, control what functions
Voluntary
Explain how the crossed extensor reflex is associated with the withdrawal reflex
The crossed extensor reflex is the extension of the opposite limb during withdrawal reflex to help balance (response is in the opposite side of input)
If the pain stimulus is on the right leg, where is the withdrawal reflex vs crossed extensor muscle reflex
Withdrawal reflex= right leg
Crossed extensor reflex= leg leg
In the lateral corticospinal pathway, where is crossover and what is it responsible for, give an example of if there was an injury to one of the body parts it’s responsible for
Crossover at medulla
Responsible for distal limbs, agile and precision (hands and feets)
Left sided injury to hands effects the left side of spinal cord on lateral tract (same side)
Plateau phase is what kind of phase
Refractory
In the ventral corticospinal pathway, where is crossover and what is it responsible for, give an example of if there was an injury to one of the body parts it’s responsible for
Crossover at spinal cord
Responsible for trunk and proximal parts of limbs
Left injury to proximal limb effects eight side of spinal cord in ventral tract (opposite side)
Tension is generated by what source in smooth muscle
ECF calcium
In smooth muscle, what must happen to myosin in order for it to bind
Kinase phosphorylates myosin and then dephosphorylated to detach
When a muscle cell is relaxed and intracellular ATP concentrations are normal, most myosin cross-bridges will remain in which of the following states?
In a high-energy state with ADP and phosphate bound to it, ready to bind to actin
In the muscle lab, what caused an increase in the recruitment of motor units?
increasing stimualtion voltage
What’s the difference between single unit and multi unit smooth muscle cells?
Single unit smooth muscles have connections to adjacent cells through gap junctions
Patients with diseases such as Parkinson’s disease and Huntington’s disease often are unable to suppress unwanted movement and struggle with memory and emotional regulation. Based on the symptoms of these diseases discussed in class, what source of input to lower motor neurons is being affected?
Basal nuclei
You have decided to start training to run a long-distance race. Which kind of muscle fibers will you be relying on to help power your endurance exercise?
slow oxidative fibers
The graph on the below shows the isometric length-tension relationship. Why does stretch of the sarcomere length to longer than 100% reduce the tension measured?
thin and thick filaments will no longer overlap as much
You have just gotten home from grocery shopping and have a lot of bags to bring inside. You try to pick up as many as you can, causing an extreme amount of tension to develop in your bicep muscles. This triggers a somatic reflex arc causing your muscles to relax to prevent injury. Which sensory receptor is involved in this reflex?
Golgi tendon organ
Select the statement below that best describes a skeletal muscle motor unit?
A. A motor neuron and all the muscle fibers it synapses on
B. A motor neuron that innervates muscle fibers from all three muscle types
C. Many motor neurons and the one muscle fiber they synapse on
A
During excitation-contraction coupling, what do Dihydropyridine (DHP) receptors in skeletal muscle facilitate?
Calcium release from the SR
At the initiation of contraction in skeletal muscle, which of the following is required?
A. Calcium binding to Ryanodine receptors (RyRs) in the sarcoplasmic reticulum
B. A shift in the position of tropomyosin which exposes myosin binding sites
C. Calcium influx into the sarcoplasmic reticulum through Dihydropyridine Receptors (DHPs) in the T-tubules
B
In the muscle lab, increasing the frequency of stimulation resulted in an increase in the size of the muscle response. What process causes this increase in muscle response to occur? Higher stimulation frequencies….
result in a net increase in intracellular calcium
The activation of smooth muscle contractions is dependent on which of the following?
phosphorylation of myosin
If the radius of a vessel has increased, then which ONE of the following could be a result?
resistance decreases
Compare the cardiac action potential in ventricular cardiac myocytes and the electrocardiogram (ECG). Which parts are most synchronous (occur at the same) with each other?
A. The plateau phase and the P-R segment.
B. DE-polarization of the cardiac action potential and the QRS complex.
C. RE-polarization of the cardiac action potential and the T wave.
B
Dr. Wu wants to increase cardiac output while maintaining the Frank-Starling relationship, with a minimal change in heart rate. Which way is the best way to do this?
increase EDV
Assuming there is little change in ESV, increasing EDV would
increase SV and cardiac output
While using a stethoscope, you hear a “whoosh” after the S1 sound because:
The left AV valve is not closing properly
There are drugs that can increase the sensitivity of Ca2+ binding to increase contractility. Which ONE of the following do these drugs likely affect? Select the best answer.
Troponin
In response to a decrease in blood pressure, which ONE of the following is predicted?
A. A further increase in blood pressure (positive feedback)
B. Acethylcholine release from the parasympathetic efferents on the SA and AV nodes
C. Greater stimulation of the a1 receptors to constrict the arterioles
C
Local control of blood flow to the capillary bed of an organ can be controlled by:
A. Constriction of precapillary sphincters at the metarterioles by endothelin
B. Parasympathetic nerves releasing acetylcholine at the arterioles
C. Dilation of the venuoles from increased CO2 in the blood
A
Which ONE of the following could cause an increase in vessel length?
An increase in body mass
Dr. Wu was lying down. He gets up and had to grasp the table to steady himself. After about half a minute of dizziness, he started to feel better. Dr. Wu felt dizzy because, upon standing:
part of his blood was displaced to the veins in his legs
Consider pressure during ventricular systole. Which ONE of the following statements about this is TRUE?
A. Aortic pressure decreases
B. Afterload must be greater than aortic pressure
C. During systole, the pressure in the ventricle does not change significantly
B
Which one of the following best describes the left and right ventricles in terms of muscle mass, wall thickness, and pressure?
A. The left ventricle is larger than the right ventricle because there is little resistance to blood flow during ventricular systole.
B. Afterload generated by the left ventricle is greater than the right ventricle resulting in a thicker left ventricular wall.
C. End diastolic volume in the right ventricle is greater than the left ventricle due to decreased preload
B
Beta blockers are used to treat patients diagnosed with heart failure. Which ONE of the following is TRUE about beta blockers?
A. They block beta1 receptors in the pacemaker cells to decrease heart rate
B. Ca2+ entry into cardiac myocytes is reduced during calcium-induced calcium release
C. Acetylcholine can no longer bind to muscarinic receptors
A
Beta blockers….
decrease heart rate to keep heart from overworking
Atrial RE-polarization is not normally observed in an ECG for which ONE of the following reasons?
it’s obscured by the positive deflection of the QRS complex
the QRS complex is a much larger deflection due to the
larger size and electrical activity of the ventricles compared to the atria
Blood plasma can go through capillary walls from the arteriolar side due to?
Net filtration occurs due to a hydrostatic pressure gradient
How would the cardiac cycle diagram change for the right heart?
Compared to the left heart, the pressures in the chambers are lower
On a normal ECG, the two bumps before the QRS complex mean that the
DE-polarization of the left atrium is occurring after the DE-polarization of the right atrium
A reduction in vessel radius can be due to:
A. An increase in nitric oxide as an intrinsic mechanism
B. The release of endothelin from endothelial cells
C. Norepinephrine binding to β2 receptors in vascular smooth muscle cells
B
Consider the right ventricle. In pulmonary arterial hypertension, there is a greater than normal blood pressure in the pulmonary artery that goes to the lungs. Which of the following is most affected?
afterload
The highest resistance is found in which of the following vessels?
arterioles
Arterioles have smooth muscle that’s innervated by the
sympathetic NS
integrates the signals from baroreceptors
cardiovascular control center
move excess calcium out of the myocyte
sodium-calcium exchanger
The cellular basis for the Frank-Starling mechanism is based on:
intracellular calcium and sarcomere length
Explain the Frank-Starling Law of the heart
increase in stroke volume, filling volume in the ventricle increases. This filling is dependent on the amount of calcium in the cell and the length of the sarcomere.
Blood flow (Q) is directly proportional to __ and inversely proportional to __
r^4, legnth
three factors that affect resistance are
radius, length, viscosity
In the left ventricle, stroke volume is the amount of blood __________ during _________.
ejected from the left ventricle, ventricular systole
The characteristic of the aorta and arteries allow for quick expansion by high volumes and pressures is called _________.
compliance
Following ventricular depolarization, the aortic valve opens, resulting in:
decrease in ventricular volume
