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Describe the thick and thin filament
- Thick: Golf club shaped protein and several hundred make one, made of myosin
- Thin: Has actin, tropomyosin, and troponin
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What is the role of calcium in the skeletal muscle contractions
Ca++ binds to troponin pulling tropomyosin off the binding site allowing actin and myosin to bind
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How does muscle shortening occur and what do you call his theory
- Sarcomere shortens and the overlap between the thick and thin filaments increase
- Sliding filament mechanism
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What are the 3 phases of the cross-bridge cycle
Binding, power stroke, and detachment
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What must happen first before the cross bridge cycle can occur
Ca++ must bind to troponin to pull tropomyosin off of the binding site so binding can occur
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Where does Ca++ come from in skeletal muscle
Sarcoplasmic reticulum
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How did Ca++ get out of the SR in skeletal muscle
An AP traveling down the T-Tubule activating the DHP-R then RR allow Ca++ channels to open in the SR
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What 3 roles does ATP have in skeletal muscle
- Energize myosin head
- Detaches myosin head from actin
- Actively transports Ca++ back to SR
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What 2 things happen to cause muscle relaxation
- Ache removes Ach and calcium
- Tropomyosin goes back to binding site
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What is a muscle twitch
Weak contraction produced by a single fiber in response to a single action potential
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What is a: motor unit, recruitment, and asynchronous recruitment
- Motor Unit: Neuron innervates multiple muscle fibers
- Recruitment: Strength & precision of contraction dependent on size of motor unit and number of units activated
- Asynchronous: Prevents fatigue, only a portion of motor units are used and alternates motor unit activity
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List 4 factors that affect the tension a muscle can generate
- Frequency of stimulation
- Length of muscle fiber at onset
- Fatigue
- Thickness of fiber
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What is the difference between twitch summation and tetany?
- Twitch Summation: Second AP arrives before a twitch is over
- Tetanus: The muscle has no chance to relax
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What are three sources of ATP in the muscle?
- Creatine phosphate
- Oxidative phospholyration
- Glycolysis
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List 3 examples of muscular fatigue in skeletal muscle
- Central fatigue
- Psychological fatigue
- Neuromuscular fatigue
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Compare and contrast skeletal and smooth muscle's thin filament
- Smooth: No troponin
- Skeletal: Actin, tropomyosin, and troponin
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Describe smooth muscle activation
- Calcium binds to calmodulin
- Calmodulin activates myosin kinase
- Kinase pulls phosphate from ATP giving ADP leading to cross-bridge
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What is the different between multi-unit and single-unit smooth muscle activation
- Multi-Unit: neurogenic
- Single-Unit: Myogenic
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Compare and contrast cardiac muscle vs skeletal and smooth muscle
- All: Sliding filament mechanism
- Cardiac & smooth: Myogenic sarcomeres and unicellular
- Skeletal & Cardiac: Striated and have thin filament
- Skeletal: Has neurogenic sarcomeres
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What are 2 types of cells of cardiac muscles
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Describe AP in autorythmic cells
- Decrease in K+ permeability and increase Ca++ permeability
- Due to transient voltage-gated channels causing the AP to occur and LL voltage gated channels to take place
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Describe the normal autorythmic conducting system
- Sinoatrial node
- Atrioventricular node
- Bundle of his
- Purkinje fibers
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What is unique about the contractile cardiac muscle cell's AP and what causes this
- Plateau in AP
- Slow lasting voltage-gates Ca++ channels
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The plateau of contractile cardiac muscle cell results in a ling refractory period. Why is this significant?
- Prevents tetanus
- Important for synchronizing contractions
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What is systole and diastole?
- systole: contraction/emptying
- diastole: relaxation/fill
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What ECG wake corresponds with ventricular systole
QRS wave
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What causes blood to flow from now heart chamber to the next
Pressure in atria exceeds pressure in ventricle to pass through valve
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What is an isovolumetric period of the cardiac cycle?
Volume in the chambers stay the same
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What is stroke volume and how do you calculate it
- Volume of blood pumped out of ventricle with each contraction of heart
- Calculated: EDV-ESV=SV
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hat is the cadiac output and how do you calculate it
- The volume of blood per minute from each ventricle
- Calculated: HR*SV=CO
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What 2 systems affect the heart rate and what changes do they cause
- Parasympathetic: Decrease heart rate
- Sympathetic: Increase heart rate
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How do we intrinsically and extrinsically regulate stroke volume
- Intrinsically: Venous return and length-tension relationship
- Extrinsically: Sympathetic stimulation and epinephrine
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What variables determine flow rate
- Pressure Gradient and resistance
- Radius
- Viscosity
- Vessel lenght
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What 3 variables determine resistance of a vessel and which has most influence
- Radius: Most influential
- Viscosity
- Length
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What is the function of arteries besides transporting blood
Pressure reservoir
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What is the function of arterioles besides transporting blood
- Regulates blood pressure
- Determines Cardiac Output
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What is the function of capillaries besides transporting blood
exchange materials by diffusion
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What is the function of veins besides transporting blood
Blood reservoir
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Define systolic pressure, diastolic pressure, pulse pressure, and mean arterial pressure
- Systolic pressure: Mac pressure during ventricular systole
- Diastolic pressure: Min pressure when blood is draining out
- Pulse pressure: Difference between systolic and diastolic pressure in mmHG
- Mean Arterial Pressure: Main driving force for blood flow and drives it forward
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What are 2 types of changes that arterioles make to alter resistance
- Vasoconstriction
- Vasodilation
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Intrinsic and extrinsic factors regulate arteriole tone but each has different aspects of blood flow. What do intrinsic regulators control?
What do extrinsic regulators control?
- Intrinsic: Control local influences on the resistance of arterioles
- Extrinsic: Control Blood pressure
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Give some examples of chemical intrinsic factors
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Why is blood velocity slowest in the capillaries
Capillaries have a small radius
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What is the purpose of a metarteriole
Regulate movement through capillary
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List the forces that control filtration and reabsorption at a capillary and indicate which ones favor filtration and which ones oppose filtration
- Hydrostatic: Favor filtration
- Oncotic: Oppose filtration
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List 3 functions of lymphatic system
- Return excess filtered fluid
- Return filtered proteins
- Defense against disease by lymph nodes
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List 5 extrinsic factors that aid in venous return
- Sympathetic stimulation
- Increased skeletal muscle activity
- Respiratory pump
- Cardiac Suction
- Valves
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What 3 factors determine blood pressure
- Cardiac output
- Total peripheral resistance
- Blood volume
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What factors would be used to regulate blood pressure on a short term basis? Long term?
- Short term: Cardiac Output and TPR
- Long term: Adjust blood volume
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