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Unit 7
Metabolism, muscles
| Question | Answer |
|---|---|
| cellular respiration | Chemical breakdown of glucose* to form ATP |
| Cellular respiration equation | C6H12O6 + 6O2 12 H2O + 6 CO2 + 36 ATP + heat |
| Glycolysis | occurs in the cytosol |
| Krebs cycle | occurs in the matrix of the mitochondria; the products of glycolysis are imported into the mitochondria |
| Electron transport chain | occurs in the cristae of the mitochondria *In A&P II, you will learn more about each of these three reactions; but you will learn a little about the first reaction (glycolysis) here |
| aerobic | Requires O2. The equation above is also called aerobic cellular respiration because it requires O2 to occur |
| anaerobic cellular respiration | ATP production without O2 Occurs by the reaction called glycolysis. Anaerobic respiration does not use all three of those reactions; it uses only the first one which is glycolysis. Notice in the reaction below, O2 is not required for glycolysis |
| Glycolysis equation | Glucose + 2ADP pyruvic acid + 2 ATP 1) Glycolysis makes only a small amount of ATP--it makes only 2 ATP (not 36 like occurs in aerobic cellular respiration) 2) Oxygen is not required |
| myology | Specialized branch of anatomy for muscular system |
| 3 types of muscle tissue | skeletal, smooth muscle tissue, cardiac muscle tissue |
| Skeletal muscle tissue | a) Located: attached to bones b) Movement: voluntary c) Striated: yes d) Function: whole body movements e) Cells are elongated (some are over a foot long), are called muscle fibers, & are multinucleate |
| Smooth muscle tissue | a) Located: walls of hollow organs b) Movement: involuntary c) Striated: no d) Function: movement of substances w/n body e) Cells are spindle shaped |
| Cardiac muscle tissue | a) Located: heart b) Movement: involuntary c) Striated: yes d) Function: move blood through heart e) Cells are branched & have intercalated discs connecting the cells |
| Functions of the muscular system | movement, stabilize, heat production, controlling body openings&passage, glucose homeostasis |
| functions of the muscular system: movement | which includes movement of the entire body (such as occurs when walking) and movement of material through the body (such as blood moving through blood vessels or partially digested food through the digestive system) |
| Functions of the muscular system: glucose homeostasis | skeletal muscles use a lot of glucose which helps to stabilize blood glucose levels |
| Properties of muscle tissue | Responsiveness: respond to stimuli. ;contract; this means they can shorten in length. The opposite of contract is relax. muscle relaxes, returns to original length;Extensible: stretch without damage;Elasticity: return to original shape and length |
| number of named muscles in the human body | 697... Each muscle is a separate organ |
| Muscle made of | 1) Thousands of muscle cells called muscle fibers 2) Blood vessels 3) Nerve fibers 4) Connective tissue (CT) |
| 3 layers of CT associated with muscles | Epimysium, perimysium, endomysium |
| Epimysium | superficial layer. Surrounds the entire muscle. Made of dense irregular CT |
| Perimysium | medial layer. Surrounds a group of muscle figures (can surround anywhere from 10-100 fibers). Made of dense irregular CT. Forms fascicles which are bundles of muscle fibers |
| Endomysium | deepest layer. Surrounds the individual fibers within a fascicle. Made of areolar CT |
| Fascicles in a muscle have different orientations as shown: Fusiform | is thick in middle & taper at ends. Fusiform muscles have many fibers and are very strong |
| Fascicles in a muscle have different orientations as shown; Parallel | : has uniform width fascicles that are orientated in parallel. Usually very long. Because they are so long, they have greater shortening ability than other muscles. They have less fibers so they produce less force (this means they are not as strong) |
| Fascicles in a muscle have different orientations as shown: Triangular (convergent) | are fan shaped. Have a large number of fibers and are very strong |
| Fascicles in a muscle have different orientations as shown: Pennate | are feather shaped. Have the largest number of fibers so they are the strongest of all muscles |
| Fascicles in a muscle have different orientations as shown: Circular (sphincters) | : form rings around body openings. Some prevent passage of material through when they contract (for example, sphincter between stomach & esophagus) |
| A muscle can be attached to: | 1) CT membrane and/or 2) Another muscle or muscles and/or 3) Bones |
| origin | where the muscle attaches to the bone that is not moving during muscle contraction |
| insertion | where the muscle attaches to the bone that is moving during muscle contraction |
| When a muscle is attached to bone, there are two types of attachments possible: Direct | epimysium fused to periosteum of bone |
| When a muscle is attached to bone, there are two types of attachments possible: Indirect | epimysium extends beyond muscle as : a) Sheet of dense irregular CT: called an aponeurosis 5 b) Cord of dense regular CT: called a tendon (in figure above a tendon connects the muscle to ulna) |
| Special features of muscle fibers: Sarcolemma | term for the cell membrane of a muscle cell |
| Special features of muscle fibers: Sarcoplasm | term for the cytoplasm of a muscle cell |
| Special features of muscle fibers: Myofibrils | thread like fibers running parallel across the cell from end to end. Are the contractile elements of cell--this means they are the parts inside the cell that actually shorten; when the myofibrils shorten, the entire cell will shorten as a result |
| Special features of muscle fibers: T-tubule | in-pockets of the sarcolemma extending down to the center of the cell. Function as a communication system: Distributes stimuli to all myofibrils in cell |
| Glycosomes | special organelles that store glycogen |
| Myoglobin | red pigment that binds O2. Functions to store O2 in cell |
| Special features of muscle fibers: Sarcoplasmic reticulum | a modified smooth endoplasmic reticulum. Surrounds the myofibrils. Function: stores and releases calcium |
| Myofibrils are striated | this means they have alternating light and dark bands Definition of the A band: the dark band Definition of the I band: the light band |
| A band has two regions | 1) H band (sometimes called H zone): lighter region in center that is visible only when the cell is relaxed 2) M line: the center of the H band |
| The I band has one region | Z disc : region in center of I band |
| sarcomere | 1) Anatomic definition: region of myofibril between two Z discs 2) Functional definition: is the functional unit of a muscle cell. This is the structure that actually allows for the shortening to occur |
| myofilaments | There are 2 types of myofilaments: 1) Thick filaments: made of myosin. About 200 myosin proteins make one thick filament 2) Thin filaments: made of actin anchored in the Z disc |
| Anatomy of myosin | Made of 2 regions: 1) Tail: points towards the M line 2) Heads: are two heads on each myosin molecule. Point towards the actin thin filament. Heads have the ability to bind to actin |
| Function of myosin | it is a contractile motor protein that binds actin |
| motor protein | a protein capable of doing work inside the cell. There are many motor proteins inside a cell, myosin is one of them. |
| Anatomy of actin: | is made of oval subunits Function of action: is a contractile protein with a myosin bind site |
| 2 regulatory proteins associated with actin | troponin & tropomyosin |
| Function of the regulatory proteins | proteins: regulate myosin binding by blocking the myosin bind site on actin |
| accessory proteins | associated with myofilaments. Functions include anchoring myofilaments in place, regulating length, and keeping sarcomere structures in alignment |
| dystrophin | Most important accessory protein.Dystrophin is the largest protein known. It is over 10,000 amino acids long. fx links the myofilaments to the sarcolemma and functions to stabilize the sarcolemma & is needed for effective muscle contraction |
| How do skeletal muscles function to cause movement? Let's use forearm flexion to answer this question on how muscles cause movement | 1) Myofilaments inside the muscle fibers shorten; this happens in all the muscle fibers making up the muscle 2) When the myofilaments shorten, the entire muscle fiber shortens |
| How do skeletal muscles function to cause movement? Let's use forearm flexion to answer this question on how muscles cause movement cont. | 3) When all the muscle fibers in a muscle shorten, the entire muscle shortens 4) Shortening of the entire muscle pulls on tendon connecting muscle to the ulna 5) This pulls ulna upward which is forearm flexion |
| Important to remember about skeletal muscle function | 1) Muscles cause movement by pulling on bones, not pushing on them |
| Important to remember about skeletal muscle function | 2) A muscle cannot perform the opposite action. For example, biceps brachii flexes the forearm, it does not cause extension of the forearm (the biceps brachii cannot "push" the ulna back down) |
| Important to remember about skeletal muscle function | Opposite movement is caused by another muscle (antagonist) usually located on the other side of the joint Ex: triceps brachii causes extension of the forearm. is connected to the ulna by a tendon. triceps contracts, the tendon pulls on the ulna |
| prime mover | the muscle that is most responsible for an action. For example, the biceps brachii is the prime mover for forearm flexion. Other muscles can assist the prime mover. These are called synergists |
| antagonist | he muscle performing the opposite action as the prime mover The antagonist opposes the prime mover. It is usually located on the opposite side of joint as the prime mover |
| sliding filament mechanism | Mechanism of muscle contraction. myofilaments slide past each other which causes the entire sarcomere to shorten |
| During the sliding filament mechanism | 1) Thin filaments slide past thick filaments 2) Thin filament pushed towards the M line 3) A bands move closer together 4) I bands shorten 5) Distance between Z discs decreases 6) H band disappears Overall result: muscle fiber contracts (shortens) |
| Steps in the sliding filament mechanism: | Nerve cell cus an action potential to occur across the sarcolemma; Action potential travels down the T tubules; Calcium binds to troponin/tropomyosin complex; Myosin becomes phosphorylated. Crossbridge formation; Powerstroke; Crossbridge detachment |
| Steps in the sliding filament mechanism: Nerve cell causes an action potential to occur across the sarcolemma | Anaction potential is a chemical change involving Na+ , K+, and neurotransmitters |
| Steps in the sliding filament mechanism: Action potential travels down the T tubules | Action potential causes Ca+ to bereleased from the SR (sarcoplasmic reticulum). Calcium concentration increases in sarcoplasm |
| Steps in the sliding filament mechanism: Calcium binds to troponin/tropomyosin complex | This destabilizes tropomyosin'sposition and causes the entire complex to shift position. This exposes the myosin bind site on actin. Myosin can now bind to actin |
| Steps in the sliding filament mechanism: Myosin becomes phosphorylated | myosin ATPase: an enzyme on the head of myosin. Performs the reaction of ATP hydrolysis. ADP + P (from ATP hydrolysis) stay attached to myosin head. Once myosin is phosphorylated, myosin has the PE to do work |
| Steps in the sliding filament mechanism: Crossbridge formation | Myosin binds to actin |
| Steps in the sliding filament mechanism: Powerstroke | ADP & P are released from head. Since P gave myosin the PE to change to the high energy position, losing the P removes the PE so the head must change back to original position which is a parallel position - low energy conformation of myosin. |
| Steps in the sliding filament mechanism: Crossbridge detachment | New molecule of ATP binds. Myosin unbinds actin. The muscle relaxes (the myofilaments slide back to their original position) |
| synapse | is the place where a nerve cell meets either: 1) Another nerve cell |
| Effector organ | which is the organ the nerve controls. The organ can be a muscle (smooth, cardiac, or skeletal) or a gland (such as the pancreas). |
| neuromuscular junction (NMJ): | a special type of synapse where nerve meets a muscle cell |
| synaptic cleft | the small space between effector organ & nerve cell. The organ and nerve cell do not physically touch, there is a small space between themcalled the synaptic cleft |
| neurotransmitter (NT) called acetylcholine (ACh) | NT are released from nerve cells by exocytosis. NT is a chemical released by nerve cells and it is how nerve cells communicate with other cells |
| What happens in nerve cell at NMJ? | The nerve cell releases a neurotransmitter (NT) called acetylcholine (ACh) |
| What does ACh do after it is released? | Travels across synaptic cleft. Binds ACh receptors on sarcolemma. Triggers action potential in muscle cell (this then causes step 1 of the sliding filament mechanism to take place |
| To stop contraction: | Nerve cell stops releasing ACh; ACh still remaining in the synaptic cleft is degraded; Ca+ pumped backed into the SR. calcium is not present, the myosin bind sites on actin are covered up. Since myosin is unable to bind, the muscle cannot contract. |
| Acetylcholine esterase | an enzyme in the synaptic cleft that destroys ACh |
| motor unit | a nerve cell and all the muscle cells it controls. The average motor unit involves about 200 muscle cells |
| small motor units | that producefine movements like finger & eye movements |
| large motor units | that produce powerful movements (such as movements produced by quadriceps femoris) |
| Muscle cells have 3 mechanisms to produce ATP which are | (1) Direct phosphorylation by creatine phosphate (2) Glycolysis and (3) Aerobic respiration |
| The three methods in muscle cells are compared and contrasted below according to : | a. Whether or not they need oxygen to occur b. The number of ATP made by the method c. The duration of the energy (this is the length of time the ATP lasts) d. The energy source (this means where the energy comes from to make ATP) |
| mechanisms to produce ATP in muscle cells: | Direct phosphorylation by creatine phosphate (CP); 2) Glycolysis:; 3) Aerobic cellular respiration |
| Direct phosphorylation by creatine phosphate (CP) | CP is phosphate storage molecule that transfers phosphate to ADP to form ATP Reaction: Creatine phosphate + ADP->Creatine + ATP Creatine phosphate replenished inside, no oxy. ATP made: 1 ATP per creatine phosphate Duration: 15s source: creatine phosphate |
| Glycolysis | anaerobic mechanism where glucose is converted into pyruvic acid Is oxygen required? No # of ATP made: 2 ATP per glucose Duration of energy: 30-60 seconds Energy source: glucose |
| Glycolysis cont. | Anaerobic respiration (glycolysis)advantageous bc it produces ATP very fast; Produces over 2x faster than aerobic respiration. disadvantage of anaerobic respiration. The disadvantage is it harvests only 5% of the total energy in the glucose molecule |
| What happens to lactic acid produced from anaerobic respiration? | diffuses out the muscle cell& enters blood. The body can use lactic acid for a) Liver can convert it to pyruvic acid or glucose. pyruvic acid&glucose can then used for energy b) Organs like brain, kidney , & heart can make ATP directly from lactic acid |
| Aerobic cellular respiration | Includes all 3 steps of cell respiration which are: (a) glycolysis (b) Krebs and (c) electron transport Is oxygen required? Yes # of ATP made: 36 ATP per glucose Duration of energy: hours Energy source: glucose |
| muscle tone | when relaxed, muscles are in state of slight contraction This slight state of contraction is not enough to produce movement (such as whole body movement) this is because the myofilaments are not completely pulled towards the M line |
| Functions of muscle tone: | 1) Maintains posture ie holding head upright when walking 2) Stabilizes joints ie as keeping bones of legs aligned to stabilize knee joint while walking 3) Keep muscles ready to respond if called upon to contract. |
| muscle tension | force a contracting muscle exerts on an object |
| load | opposing force exerted on muscle by object being moved. Load can be thought of as the weight of the object because load is proportional to weight. For example, a 50 lb weight has a bigger load than a 5 lb weight |
| What happens if tension > load? (“ >” means “greater than”) | Tension overcomes load and the load is moved. Example: muscles of your arm can generate enough tension to overcome load of your A&P text and you can pick up the text |
| What happens if tension is < load? (“<” means “less than”) | Tension does not overcome load so the load is not moved. Example: muscles of your arm cannot generate enough tension to overcome the load of your car so you cannot pick up your car |
| There are 3 possible lengths of muscle | Overly stretched ; ) Medium stretched; Under stretched (which is really overly contracted as the figure shows below) |
| There are 3 possible lengths of muscle: Overly stretched | If fibers are in the overly stretched position before contraction, how does it influence muscle contraction? It causes less tension to be produced. |
| There are 3 possible lengths of muscle: Medium stretched | If fibers are the medium stretch position before contraction, how does it influence muscle contraction? It will result in optimum tension being generated |
| There are 3 possible lengths of muscle: Under stretched which is really overly contracted | If fibers the overly contracted state before contraction, how does that influence muscle contraction? It will result in less force being produced |
| Exercise can also influence the amount of tension produced: Resistance exercises | result in enlargement of muscle cells over time. Resistance exercises are ones where contraction is done against a high load force. Example of a resistance exercise: lifting weights |
| Exercise can also influence the amount of tension produced: Aerobic exercises | results in more efficient metabolism inside the muscle cell because it increases the number of capillaries, the number of mitochondria, and the amount of myoglobin. Aerobic exercises are endurance activities. Example of an aerobic exercise: running |
| muscle twitch | motor unit response to 1 action potential Duration: 20 to 200 milliseconds |
| myogram | a graphic representation of muscle twitch |
| 3 phases of myogram | Latent, Contraction, Relaxation |
| 3 phases of myogram: Latent | this is a period before contraction actually begins and corresponds to the time it takes for action potential to cause muscle contraction. During this time, Ca is being released from the SR and myosin begins forming crossbridges |
| 3 phases of myogram: Contraction | this is the period when contraction is happening |
| 3 phases of myogram: Relaxation | this is period after muscle contraction when the muscle relaxes and corresponds to the time when Ca is going back into the SR and the filaments return to their original position |
| Myogram response varies by muscle | The response can be fast or slow. Whether it is fast or slow is determined by the speed at which the myosin ATPase hydrolyzes ATP |
| fast twitch muscle | has a fast response because the myosin ATPase hydrolyzes ATP fast |
| slow twitch muscle | has a slow response because the myosin ATPas hydrolyzes ATP slower |
| muscle fatigue | physiological inability to contract even though stimuli is still being sent from the nerve cell |
| Causes of muscle fatigue for high intensity, short duration exercises | Build up of K+: interferes with ability to generate action potential across sarcolemma; Build up of ADP & P: this slows down function of the myosin ATPase 3) Lactic acid accumulation: lowers pH of sarcoplasm which then interferes with the role of Ca+ |
| Causes of muscle fatigue for low intensity, long duration exercises: | 1) Depletion of glycogen & glucose 2) Loss of electrolytes through perspiration which then can decrease the ability to generate an action potential 3) Decrease stimulation of muscles from the central nervous system |
| oxygen debt | difference between the amount of oxygen consumed at rest versus the amount consumed after exercise |
| Oxygen debt is the reason you breath heavy for a few minutes after you have stopped exercises. | Extra oxygen is needed:Replacing oxygen stored in myoglobin & in hemoglobin; Replacing CP; Oxidizing lactic acid: oxidation of lactic acid allows other organs to use it for energy |
| Slow oxidative | Slow Oxidative – Contraction speed slow, Myosin ATPase speed slow, Primary method to make ATP aerobic, Myoglobin contact high, Glycogen stores low, fatigue slow, color red, fiber diameter small, mitochondria many, capillaries many, activities endurance |
| Fast Oxidative | Fast Oxidative, Contraction speed fast, Myosin ATPase speed fast, method aerobic/anaerobic, Myoglobin high, Glycogen stores intermediate, fatigue intermediate, color red/pink, fiber diameter intermediate,mitochondria/capillaries many, activities sprinting |
| Fast Glyoltic | Fast glyolytic Contraction speed fast, Myosin ATPase speed fast, method anaerobic, Myoglobin contact low, Glycogen stores high, fatigue fast, color white, fiber diameter larger, mitochondria/capillaries few , activities short term intense/powerful move |
Created by:
cberrios
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