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BIOL 1142 - Exam 2
muscle, cardiovascular system
| Question | Answer |
|---|---|
| 3 types of muscles | skeletal, smooth, cardiac |
| skeletal muscle | muscle that moves the skeleton |
| smooth muscle | muscle used by internal organs (usually for constricting, squeezing - for example, blood vessels, glands) |
| cardiac muscle | found ONLY in the heart |
| sarcolemma | cell membrane/plasma membrane |
| t-tubules | invaginations/tunnels of sarcolemma that penetrate through the thickness of the cell; allow action potentials to quickly reach all of the skeletal muscle |
| sarcoplasmic reticulum | calcium storage |
| terminal cisternae | enlarged areas of sarcoplasmic reticulum that surround t-tubules; usually a pair of terminal cisternae associated with a t-tubule |
| myofibrils | long protein fiber composed of repeating units of sarcomeres |
| action potentials for muscle cells | action potentials require plasma membrane; muscle cell action potentials differ from other action potentials because they need to activate the entire cell thickness |
| microanatomy of skeletal muscle | skeletal muscle -> muscle fascicles -> individual muscle fibers -> myofibrils -> sarcomeres [more details of each division on power point slide chart] |
| Z disk | boundary between adjacent sarcomeres; Z-disks line up to give skeletal muscle a striated appearance |
| I band | light bands, composed of actin (thin) filaments |
| A band | dark bands, composed of myosin (thick) filaments |
| sarcomere | smallest contractile unit of a skeletal or cardiac muscle cell; composed of a Z-disk, 1/2 of an I band (actin - thin, light), A band (myosin - thick, dark), 1/2 of an I band (actin - thin, light), Z disk |
| myosin | thick filaments; associated with A bands; motor protein |
| tropomyosin | blocks the one place on each actin fiber where myosin can bind; helpd in place/postioned by troponin |
| troponin | holds tropomyosin in position until calcium binds with it; calcium binds, changes shape, tropomyosin pulls away from the myosin binding site and allows actin to bind |
| neuromuscular junction | synapse of the motor neuron and the motor end plate; where acetylcholine is released and binds to a nicotinic acetylcholine receptor, results in depolarization of muscle fiber and action potential results |
| excitation-contraction coupling | how an action potential results in the shortening of a muscle cell - link between the action potential in the sarcolemma and the contraction of the muscle |
| contraction-relaxation cycle | the actual shortening of a muscle cell |
| acetylcholine | neurotransmitter released by motor neurons that causes muscle contraction |
| action potential -> muscle contraction??? describe this slide better | Ach released -> binds to AChR at motor end plate -> Na+ enters the cell, causing depolarization -> volt. gated DHP receptors activate -> mech. gated Ca++ channels open -> Ca++ out of SR into sarcoplasm -> Ca++ binds to troponin -> contraction begins |
| rigor mortis | occurs after death; lasts 24-48 hours; muscles contract and no ATP is available to release the myosin from the actin; eventually lysosomes break down muscle cells |
| twitch | muscle fiber response to a single action potential by the motor neuron; twitches can summate; maximum frequency is called tetanus (steady tension) |
| properties that vary by muscle fiber type | speed and tension of onset; maximum tension; duration of twitch |
| factors that affect tension | sarcomere length - muscles have a "sweet spot" where they can produce maximum force); motor neuron frequency; |
| alternate pathways for ATP production in skeletal muscle | (1) creatine phosphate (2) oxidative phosphorylation (3) glycolysis |
| motor unit | motor neuron and all of the muscle cells it innervates |
| slow-twitch fibers | small diameter, low tension, long endurance |
| fast-twitch oxidative-glycolytic fibers | medium tension, endurance or short bursts, respond well to "training" |
| fast-twitch glycolitic fibers | highest force, tire quickly |
| recruitment | when the brain matches the strength of a movement with the correct number of units needed to perform a specific task |
| asynchronous recruitment | nervous system spreads the task amongst a pool of motor units and alternates which units are being used at a given time; good for long activities that require low strength (eg, maintaining posture) |
| isometric contraction | tension remains static; "same length" ex - applying force to try and move an immovable object |
| isotonic contraction | same force, changes in length; concentric or eccentric |
| eccentric isotonic contraction | lengthening muscle contractions |
| concentric isotonic contractions | shortening muscle contractions |
| control of smooth muscle | involuntary; controlled by autonomic nervous system, endocrine system, paracrines, or may be mechanically controlled |
| anatomical differences between skeletal muscle and smooth muscle | smooth muscle is electrically coupled with gap junctions so that excitation can easily spread between cells; smooth muscle has much more complicated anatomy; smooth muscle fibers have longer actin and myosin filamnets, no T-tubules, no sarcomeres |
| different types of smooth muscle | locations include: blood vessels, GI tract, urinary tract, respiratory tract, reproductive tract, ocular |
| functional differences between skeletal muscle and smooth muscle | smooth can depolarize (excite) or hyperpolarize (inhibit); smooth controlled by nervous system or hormones, skeletal only by somatic neurons; smooth has slow, variable tension in multiple directions; Ca++ activates smooth from outside cell |
| cardiovascular system parts and function | blood vessels, blood and the heart; primary function is transport of gasses, heat, waste, water, hormones, nutrients |
| anatomical features of the heart | 2 functional halves divided by interventricular septum; right side - pulmonary circulation, left side - systemic circulation; pericardium (serous membrane), myocardium (muscular wall of the heart), endocardium (thin endothelium inner lining) |
| pulmonary circulation | vena cava -> right atrium -> right atrioventricular valve -> right ventricle -> pulmonary semilunar valve -> pulmonary arteries -> lungs -> pulmonary veins |
| systemic circulation | pulmonary veins -> left atrium -> left atrioventricular valve -> left ventricle -> aortic semilunar valve -> aorta -> arteries to organs -> returns to heart via inferior/superior vena cava |
| heart valves | (1) right atrioventricular valve (tricuspid) (2) pulmonary semilunar valve (3) left atrioventricular valve (bicuspid) (4) aortic semilunar valve |
| differences between cardiac muscle and skeletal muscle | smaller, 1 nucleus; branch, joined by intercalated discs; electrically coupled; graded contractions; require oxygen; wildly different action potentials; have desmosomes and gap junctions; contractions do not summate |
| 2 types of cardiac muscle cells | (1) contractile (2) autorhythmic |
| myocardial contractile cells | about 99% of cardiac muscle cells; primary actors in the heart; resting membrane potential is -90 mV; action potential includes depolarization phase, plateau phase, repolarization phase |
| myocardial autorhytmic cells | "pacemaker" cells; highly specialized; functions entirely in action potential production, electrical signal pathway; no sarcomeres or myofibrils, cannot contract; no stable resting membrane potential, each group of pacemaker cells have their own rhythm |
| cardiac muscle action potentials | depolarization - voltage gated Na+ channles open/ends when they close; plateau phase - voltage gated Ca++ channels open/ends when they close; repolarization phase - voltage gated K+ channels open |
| pacemaker potential | unstable "resting" state of myocardial autorhythmic cells |
| "funny channel" | resting membrane potential of myocardial autorhythmic cells; varies widely |
| electrical signal travel through the heart | SA node -> atrial internodal pathway -> AV node -> Bundle of His (AV bundle) -> right and left bundle branches -> Purkinje fibers |
| AV node | located in the inferior right atrium, 50 BPM if allowed to self-regulate, |
| SA node | located in the superior right atrium, rhythmicity of 90-100 BPM |
| Bundle of His | AV bundle; electrically connects the atria and the ventricles |
| right and left bundle branches | branches of the AV bundle that connect to Purkinje fibers located at the apex of the heart |
| Purkinje fibers | transmit electrical signals to the contractile cardiac muscle cells and allow the heart to contract |
| ANS role in autorhytmicity | pSNS nervous system releases ACh which binds with muscarinic (nicotinic) receptors on the SA node and slows heartrate; SNS releases epinephrine which binds to beta 1 adrenergic receptors on the SA node to increase heart rate |
| ECG | electrocardiogram; picks up contractile cell activity and shows electrical activity of the heart, heart rate, heart rhythm, conduction velocity and abnormal physiology |
| ECG waves | P wave - bump QRS wave - spike T wave - bump P wave - P wave - one cardiac cycle |
| 12 lead ECG | 12 leads are placed at different parts of the body, allowing reading of electrical signals across several different parts of the heart |
| cardiac cycle | all of the events that happen inside the heart during a single heart beat - electrical activity, muscle contraction, muscle relaxation, changes in blood pressure, changes in volume |
| diastole | relaxation of the heart, filling |
| systole | contraction of the heart, emptying |
| atrial systole | atrial contraction, about 100 msec of each heartbeat |
| atrial diastole | atrial relaxation, about 700 msec of each heartbeat |
| ventricular systole | ventricular contraction, has several phases, about 250 msec of each heartbeat |
| ventricular diastole | ventricular relaxation, lasts until next ventricular systole (some overlap with atrial systole and atrial diastole) |
| mid-ventricular diastole | just prior to the P wave on ECG; venous pressure > atrial pressure > ventricular pressure results in blood flowing into the ventricles; AV valve open, SL valve closed |
| late ventricular diastole | Atrial Systole; P wave on the ECG; atrial pressure > ventricular pressure results in blood flowing into ventricles; AV valve open, SL valve closed; about 30% of blood volume fills ventricles b/c of contraction |
| early ventricular systole | QRS wave on the ECG; ventricular pressure > atrial pressure but ventricular pressure < aortic pressure results in no blood flow; AV valve closed, SL valve closed |
| end diastolic volume | maximum volume of the ventricles, also known as preload |
| S1 | heart sound 1; heard when AV valve closes because ventricular pressure becomes higher than atrial pressure |
| isovolumetric contraction | when heart is contracting but there is no volume changes because all valves are closed due to aterial pressure being greater than ventricular pressure |
| average arterial pressure | 120 (systolic)/80 (diastolic) |
| ventricular systole | S-T segment to mid T-wave on ECG; ventricular pressure > aortic pressure results in ejection of blood from the heart into the arteries; AV valve closed, SL valve open |
| ejection | functional contraction, pumping of blood out into the arteries via the aorta or pulmonary trunk |
| early ventricular diastole | second half of the T-wave on ECG; ventricular pressure > atrial pressure but atrial pressure < aortic pressure results in no blood flow; AV valve closed, SL valve closed |
| isovolumetric relaxation | during early ventricular diastole when all valves are closed and no blood is flowing |
| S2 | heart sound 2, heard when semilunar valve closes |
| end systolic volume | minimum volume of the heart, after blood has been ejected from the heart |
| stroke volume | difference between end diastolic volume (EDV/max volume) and end systolic volume (ESV/min volume); average normal stroke volume is 70 mL per minute ; influenced by length of cardiac muscle fibers before contraction (stretch) and force of contraction |
| cardiac output | volume of blood pumped by a ventricle in one minute; calculated by Heart Rate X Stroke Volume; average normal cardiac output is 4900 mL/min |
| heart rate | 70 BPM is normal average heart rate, calculated by measuring the time between beats |
| pSNS role in modulation of heart rate | tonic parasympathetic activity at the SA node at rest; slows SA node, increases AV node delay, weakens atrial contraction |
| SNS role in modulation of heart rate | speeds SA node, decreases AV node delay, strengthens atrial/ventricular contractions, increases secretion of epinephrine from adrenal medulla, venous constriction results in increase in venous return |
| preload | end diastolic volume (max volume), or how much the ventricles are already stretched before contraction |
| skeletal muscle pump | contraction of skeletal muscles compresses veins and assists blood in returning to heart |
| respiratory pump | change in thoracic pressure due to breathing assists blood in returning to heart |
| afterload | amount of pressure that the ventricle has to generate in order to eject blood into the aorta; affected by aortic pressure (ie, hypertension can place increase workload on the heart) |
| Starling's law | increase in end diastolic volume -> increase in force and increase in stroke volume |
| actin | thin filaments; associated with I bands; myosin binds here to allow sarcomere to shorten/contract |
| resting membrane potential for a skeletal muscle fiber | -90 mV (same as the equilibrium potential for K+) |
| amount of time a skeletal muscle action potential takes | ~10 msec |
| muscle contraction | Ca++ binds to troponin -> moves tropomyosin away from myosin binding site -> myosin heads bind to actin -> release ADP/inorganic phosphates -> power stroke shortens sarcomere -> ATP release actin -> myosin returns to high energy state |
| muscle fatigue | muscle loses the ability to maintain high tension; unsure of exact cause |
| things that affect how much force a muscle can produce | more myofibrils = more sarcomeres = more force |
| creatine phosphate | alternate pathway for ATP production; transfers to ADP readily, converts to ATP at rest; takes energy but is rapid |
| oxidative phosphorylation | alternate pathway for ATP production; mitochondrial production of ATP, slow and limited in how much can be produced, better for endurance activities |
| glycolysis | alternate pathway for ATP production; produces 2 ATP rapidly when glucose is broken down into pyruvate; limited by glucose supplies; lactic acid buildup happens because it can occur anaerobically |
| fibrous skeleton of the heart | between atria and ventricles, valves, coronary sulcus. Electrical insulator, provides complete and total electrical separation from atria and ventricles except for AV bundle. |
| blood flow through the heart | vena cava -> right atrium -> tricuspid valve -> right ventricle -> pulmonary semilunar valve -> pulmonary arteries -> lungs -> pulmonary veins -> left atrium -> bicuspid valve -> left ventricle -> aortic semilunar valve -> aorta |
| chordae tendineae, papillary muscles | prevent prolapse of tricuspid and bicuspid valves |
| ECG waves and the cardiac cycle | P wave - atrial depolarization/systole PQ - plateau phase (atrial diastole) QRS wave - ventricular depolarization ST - plateau (ventricular systole) T wave - ventricular repolarization TP - at resting membrane potential for both atria and ventricles |
| direction of blood flow and pressure | blood always flows from high to low pressue |
| cardiac cycle | all chambers in diastole -> atrial systole -> end diastolic volume -> ventricular systole/atrial diastole -> S1/isovolumetric contraction/ventricular ejection/end-systolic volume -> ventricular diastole -> S2/isovolumetric relaxation |
| Wigger's diagram | graphical summary of all parts of the cardiac cycle |
Created by:
pinklrt98
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