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Troponin and tropomyosin work together to regulate?
The attachment of cross bridges to actin
Troponin and tropomyosin serve as a switch for?
Muscle contraction and relaxation
______ must interact with Ca to move ______ in order for cross bridges to?
- For cross bridges to attach to actin
Troponin is atttached to the protein ______ and lies within the groove between ____?
- actin filaments in muscle tissue
_____ blocks the active binding site on actin
____ binds to troponin to remove ____. This allows myosin to bind to actin for the ____ ____ ____
- Cross bridge cycle
calcium release receptors aka?
When a muscle fiber is stimulated to contract by either a ___ ___ (in vivo) or ____ ____ (in vitro), the stored Ca2+ is released from the _____ ____ by ____ ____ through which membrane channels?
- motor neuron- in vivo
- electric shocks- in vitro
- sarcoplasmic reticulum
- passive diffusion
- calcium release channels or ryanodine receptors
_____ ____ are like plugs, ______ induces this "plug" to pull out of the ____ ____ ___ which allows __ to flow out.
- Ryanodine receptors
- calcium release channel
As ryanodine receptors allow Ca to flow out, Ca _____ and binds to ____ to induce ___ ____ ____. Ca is then _____ ____ back into the ____
- diffuses and binds to troponin
- cross bridge cycling
- actively transported
The conduction of action potentials along the _____ _____ stimulates the opening of ____ ____ channels. These channels in the _____ ____ are ____ coupled to Ca++ release channels to stimulate _____
- Transverse tubules
- voltage gated channels
- Transverse tubules
The protein that primarily makes up the thick filaments
_____ filament in muscle does not move and _____ slides over myosin
HCN aka ____ ___ ____ channels are the main channels involved in making _____ occur.
- Hyperpolarizing cyclic nucleotide channels
What type of gates are HCN channels? What does this generally mean?
- Voltage and Chemical gates
- Meaning they respond to changes in voltage and chemicals.
In HCNs, as ___ enters, ___ leaves. Which moves faster? What is the effect?
- Na enters as K leaves
- Na enters faster than K leaves
- The effect is excitatory
HCN channels have a ______ threshold, meaning?
As a voltage becomes more negative, it hits threshold and activates the channel.
Funny channels aka ____ channels. In pertinence to pacemaker potentials are activated during ______ to allow? Which results in?
- HCN channels
- Allow influx of Na+ and efflux of K+
- Resulting in slow accumulation of positive charge (Slow depolarization)
In pertinence to pacemaker potentials, HCNs are activated by the binding of ___ and ___ to ____ receptors via ___ ___ ____ on the cell membrane
- Norepinephrine and Epinephrine to Beta 1 receptors
- via Second Messenger System
In pertinence to pacemaker potentials, HCNs stay open briefly as the membrane ______ to a threshold value for _____ ___ channels
- T-type Ca++ channels
Cardiac action potential has a long ____ ____ ____
absolute refractory period
Cardiac action potential steps:
rapid depolarization, then repolarization, then goes sideways (plateau phase) and then repolarizes all the way
____ ____ ____ requires an outside excitation force
Cardiac action potential
Why do cardiac action potentials have a long plateau phase?
How long does the cardiac action potential last?
In cardiac action potential, when does the cell contract?
After action potential (which is after depolarization and repolarization), **they are superimposed and latent in between.
When does the contraction end? (Cardiac Action Potential)
In Cardiac action potentials, the relaxation begins in which phase?
Absolute refractory period
In cardiac action potentials, when does the twitch/contraction following absolute refractory period occur?
Relative refractory period
In cardiac action potentials, when does the contraction following relative refractory period occur?
None of the contractions of cardiac action potentials can fuse together, why is that?
This is because the earliest contraction occurs when the muscle starts to relax (no summation). As a result, there will always be a relaxation period which prevents tetanus from occurring.
Cardiac APs are characterized by ____ ____, which the hits a _____ phase, which then leads to a slow _____.
- rapid depolarization
- slow repolarization
As pacemaker potentials spread away from ___ node, they become _____ ___.
Individual ______ cells are linked together by ___ ____, which allow the potential to travel into the next cell
Figure 13.19 phase 0
- Rapid depolarization
- -Na+ channels open
- -T-type Ca++ channels open and close rapidly
- -L-type Ca++ channels begin to open and are ineffective
Figure 13.19 Phase 1
- Early rapid repolarization
- -Na+ channels closes
- -Transient-outward K+ (K+TO) channel opens and closes rapidly
- -Na+/Ca++ exchanger expels Na+ and imports Ca++
Figure 13.19 Phase 2
- Plateau phase
- -L-type Ca++ channels fully open and effective
- -K+ channels open
Figure 13.19 Phase 3
- Final rapid repolarization
- -L-type Ca++ channels closed
- -K+ channels stays open for efflux of K+
Figure 13.19 Phase 4
-heart chambers are filling
In phase 0 of myodcardial APs, ___ ____ occurs due to the opening of __ ___ ___. Simultaneously, T-type channels add a little extra Ca to help get to ____ and L-type channels begin _____
- rapid depolarization
- Na voltage channels
In phase 1 of myocardial APs, __ ___ ___ occurs due to the closing of ___ ____. The opening of transient outward K channels causes the ___ of __ and the Na/Ca exchanger which imports __ and kicks out __. Na is expelled more rapidly than ___ is imported which causes a net loss of ___ ___. The phase ends with ___ ___ of Na out and ____ of K
- Early rapid repolarization
- Na channels
- efflux of K
- imports Ca and kicks out Na.
- Ca is imported
- Net loss of positive charge
- Active transport
In phase 2 of Cardiac APs aka the ____ phase, why do l-type channels finally become effective? Influx of ____ through ___ ___ ___ channels (___) occurs
- because they open slowly
- Calcium through standard calcium voltage channels (l-type)
In phase 3, the ____ ___ ____ occurs. The l-type channels ___ and ____ channels remain opened. There are also continued effects of the ___ ___ channel
- Final rapid repolarization
- potassium channels
- potassium voltage
In phase 4, the chambers fill and the _____ cells produce another ___ ____. This phase is also known as _____ _____ phase
- pacemaker cells
- action potential
- diastolic depolarization
P-waves indicate the spread of ______ through the ____ which causes an upward deflection. This is represented in the ___ segment. When the entire mass of the atria is ____, the ECG returns to baseline. Why?
- PR segment
- Because all regions of the atria have the same polarity
Segment is ____; interval is ____
The PR segment measures the ____ ____ of slow conduction through the ___ ___ and bundle of his. Then right and left bundle branches on the _______ ____. The PR segment also measures?
- Electrical activity
- Av node
- Isoelectric line
- Currents too small to generate action potentials
What converts the myosin head into the high-energy state?
They hydrolysis of ATP converts the myosin head into the high energy state
The release of an inorganic phosphate from the myosin molecule directly results in?
The release of an inorganic phosphate from the myosin molecule directly results in a power stroke
Forced expiratory volume in one second which is measured during spirometry lab to test lung volume and performance
In order for crossbridge cycling to occur, the actin-myosin complex must be broken by?
The actin-myosin complex must be broke by binding of ATP to myosin
The sequence of events that links the action potential to changes in skeletal muscle force development is called?
Increases in the amount of cytoplasmic calcium required to initiate a muscle contraction are mediated by the coupling between a _____ on the T tubule and a ____ on the membrane of the sarcoplasmic reticulum
- Dihydropyridine receptor
- ryanodine receptor
Optimum length for producing maximal tension in skeletal muscle
2.25mm aka resting sarcomere length
If skeletal muscle is hyperextended beyond the optimum length, what occurs
- We cannot generate any muscle tension
- The thin filaments are pulled away from the thick filaments, thereby reducing actin's ability to interact with myosin.
- Strength of contraction is decreased because of fewer actin and myosin cross bridge interactions
As the sarcomere length of skeletal muscle is reduced beyond the length where optimum force is developed...
- There is interference between the thin filaments (they overlap because they have nowhere else to go).
- They can't generate muscle tension.
- The muscle contraction force is decreased because the sarcomere is short and cross bridge cycling is ineffective
What is an increase in the number of active motor units that would increase the force developed by a skeletal muscle called?
the recruitment of additional and larger motor units with more muscle fibers per motor neuron to increase the force of contraction
_____ is composed of multiple globular molecules polymerized to form long chains or filaments
Each myosin head has a binding site for ___ and ___
Actin and ATP
The molecular event that occurs immediately after the power stroke is the...
release of ADP and an inorganic phosphate from the myosin
The relaxation of skeletal muscle relies on the activity of the _____ which decreases cytoplasmic calcium concentration
Ca is ____ ____ back into the ____ once ____ ____ ___ is completed
- actively transported
- cross bridge cycling
The brief period of time between the beginning of the action potential in the muscle and the beginning of contraction is referred to as?
latent period- amount of time it takes for Ca to be release and cross bridge cycling to occur
The slow depolarization in the SA node is from HCN channels activated during _____ and allow ____ of Na+ and ____ of K+ simultaneously resulting in?
- Slow accumulation of positive charge in the cell
T-type Ca++ voltage channels open and allow for brief ____ of Ca++; ____ ___ inhibits HCN channels
- They are tube like proteins that link together myocardial cells.
- When 1 cell depolarizes, the depolarization will move into the next cell due to gap junctions.
How do gap junctions help action potentials travel from one cell to the next cardiac cells?
They can change diameter to minimize damage to other cells; larger diameter has less resistance
When cells depolarize and _____ enters, it will move to the next cell through the ___ ____. So the ____ ____ can move form one cell to next via ___ _____ and thus can move very rapidly from one cell to the next
- gap junctions
- action potential
- gap junctions
When cells are connected by gap junctions, they behave like?
One whole unit, the entire heart depolarizes in a very short period of time because of the way the action potential spreads rapidly
The property of cardiac tissue that results in greater current flow along the length of a fiber rather than along its width
The opening and closure of the atrioventricular and semilunar valves is driven by _____
There must be a change in pressure between ___ and ____ for valves to open and close
Atria and ventricles
Movement of blood happens through the development of _____ _____
Atria has ___ pressure, the ventricles has ___ pressure, and artery has ____ pressure during diastolic period.
As the systolic period occurs, the atrial pressure _____, the ventricular pressure ______, and the arterial pressure ______. When the pressure becomes too high in the ventricle, what happens?
- The valve opens and blood is ejected into systemic circuit
Closure of the atrioventricular valve occurs when?
Atrial pressure is low and ventricular pressure is high; beginning of systole
What are the two major regions of the heart containing pacemaker cell?
- Sinoatrial node (SA node)
- Atrioventricular node (AV node)
Which of the following is the correct conduction pathway through the heart?
- SA node
- AV node
- Bundle of His
- Bundle branches
- Purkinje fibers
The rapid depolarization phase of a pacemaker cell's action potential is caused by which type of ion movement?
- Na+ enters the cell
- Small amount of Ca++ entering
- **movement of calcium through L-type channels
Which ion channels must open for a cardiac pacemaker cell to depolarize to the threshold for an action potential?
HCN channels and T-type Ca++ channels
What is the role of ryanodine receptors in cardiac muscle?
- ryanodine receptors open to release calcium from the sarcoplasmic reticulum
- **release of Ca++ leads to muscle contraction
Which components of an ECG represents ventricular depolarization?
Which of the following components of an ECG represents ventricular repolarization
If damage to the AV node slowed down conduction through the tissue, what would be observed on an ECG?
Longer PR interval, Heart block (1st, 2nd or 3rd degree)
During isovolumetric relaxation, there is no change in the _____ of blood because the valves are _____. Blood cannot move if the valves are _____. _____ continues to relax and open up during _____ period. What percentage of the ventricle is filled before the atria contracts?
During isovolumetric relaxation, the atria is yet to _____. This will followed by ventricular _____; atrial pressure is ____ and ____, ventricular pressure is ___ and _____, artery pressure is ____. Semilunar valves and the AV valves are _____
- low and rising
- high and decreasing
What is occurring during ventricular ejection?
Blood in the ventricle is under increasingly high pressure which eventually forces the semilunar valve to open. Contraction of the ventricle occurs, and the blood is ejected into the systemic circuit and transported to body tissues.
The the ventricular filling phase of the cardiac cycle occurs during the ______, 80% is filled prior to _____ _____, pressure is rising in the _____ and decreasing in _____; __ ____ open.
- atrial contraction
- AV valves
The purpose of having valves in the cardiovascular system is to
prevent backflow of blood and keep the blood moving in one direction
The flattening of the action potentials of myocardial contractile cells, called plateau phase, is due to a combination of ____ K+ permeability and ____ Ca2+ permeability
The end of the plateau phase is due to the ______ of Ca2+ channels and ______ of K+ channels
Closure of L-type Ca channels stops Ca from?
K channels opening allows?
- Ca from coming in
- Allowing K to leave
The importance of the plateau phase of the action potential of myocardial cells is in?
Preventing another action potential during contraction because of a long refractory period
In which situation would the stroke volume be the greatest?
- Stronger contractility,
- high EDV (end diastolic volume),
- high preload which leads to shorter filling time
- venous return increased with elevated HR;
- positive inotropoic effect from cardiac muscle with epinephrine
Manganese ions block the calcium channels in the cardiac muscle membrane. How would the presence of manganese in the extracellular fluid affect the contraction of the heart muscle?
The heart will beat less forcefully
Drugs known as calcium channel blockers can be used to?
- Lessen the force of cardiac contraction
- **Decrease workload of ventricles to eject blood by inhibiting T-type and L-type Ca++ channels to slow heart rate
- cause vasodilation by blocking smooth muscle calcium channels to prevent vasoconstriction
- blocks calcium channels of pacemaker cells
- decreases oxygen demand on the heart
The actual sites of gas exchange within the lungs are
The lungs are enclosed in? The inner layer, which is attached to the ___, is the ____ layer. The outer layer, which is attached to the _____ ____, is the _____ layer. A thin layer of fluid in the _____ cavity holds _____ and ____ membranes together. Both layers connect to the _____ cavity
- A double membrane called the pleural membrane
- visceral layer
- chest wall
- parietal layer
- pleural cavity
- visceral and parietal
- Thoracic cavity
Which cells produce surfactant. Surfactant helps to reduce the ____ ____ of water, making it easier for the lungs to _____. Since the alveoli are ___ on the inside, it would be difficult to _____ the lungs w/out _____ because the lung would stick to ____. Like a balloon with a wet inner surface.
- Type II alveolar cells
- surface tension
Air moves into the lungs because? What contracts?
- Difference in atmospheric and intrapulmonary pressures.
- The diaphragm contracts (flattens/ lowers) and increases lung volume
- **Atmospheric pressure has to be high and lung pressure must be low
Intrapulmonary pressure must be _____ for air movement to occur. If atmospheric pressure and intrapulmonary pressure are ____ air movement will not occur. Why
- Air wants to move from an area of higher to lower concentration
For air moves out of the lungs because
The gas pressure in the lungs becomes higher than the outside pressure as the diaphragm contracts
Boyle's law states what about gas volume?
Inversely proportional to pressure, if the volume goes up, the pressure goes down and vice versa
Segment represents? Whereas interval represents?
The PR interval represents?
Interval of time between beginning of atrial depolarization and beginning of ventricular depolarization
P-waves indicate the spread of depolarization through the atria which causes an upward deflection.
During the P-R segment, when the entire mass of the atria is depolarized, what occurs?
The ECG returns to baseline because all regions of the atria have the same polarity (same as atrial contraction)
The S-T segment represents a significant part of _____ ______. If there is a lack of blood flow and O2 getting the heart, what happens? Why can the S-T segment be elevated above the iso-electric line?
- ventricle repolarization
- We see changes in electricity in the ST segment on an electrocardiograph
- Due to an ischemic condition
Most of the oxygen transported by the blood is?
Bound to hemoglobin in RBCs
Red blood cells give up all of their ____ to make room for ____, so the oxygen can bind to it and be transported. Red blood cells do not consume any of the __ they transport
Most of the carbon dioxide in the blood is transported as ____ ___
When CO2 combines with ____ and is aided by the enzyme ____ _____, it forms carbonic acid. Carbonic acid wants to dump its ____ into the blood, but if there are too many ___ floating around, it decreases blood pH and makes blood more ____.
- carbonic anhydrase
Carbonic acid dissociates into _____ and ____. The _____ acts as a buffer in the blood and helps reduce the instability of __. Since the red blood cell gives up _____, it must take on a chloride molecule to maintain its ____. What is this called?
- protons and bicarbonate
- the chloride shift
The most important chemical regulator of ventilation is?
CO2, it is what drives breathing (not O2)
An increase in the level of carbon dioxide in the blood will?
Lower pH (make blood more acidic) and begin negative feedback loop to breathe more
The negative feedback loop triggered when an increase in the level of CO2 in the blood...
Chemoreceptors, such as aortic and carotid bodies sense, that CO2 levels are rising, and send a signal to the medulla which sends a signal to the spinal cord to initiate breathing
Hyperventilation would lead to a(n) ______ within the systemic arteries (partial pressures)
Increase in pO2 and decrease in pCO2
In hyperventilation, less carbonic acid is formed than usual, what does this result in?
Depletion of carbonic acid raises the pH of the blood
What is the deficiency of oxygen in the tissues called?
A heart attack or the heart being deprived of oxygen in any way, the patient becomes _____ (reduced blood flow) which leads to _____
- hypoxia (reduced oxygen to tissues)