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Bio319 Lecture Exam 3
QUESTIONS AND ANSWER
202 4/2025 GRADED A+
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What are the two excitable tissues? muscle and nervous What is an example of molecular interaction facilitating conformational change? When a neurotransmitter binds to a receptor which is going to turn into a channel If we let in sodium or calcium, are we going to go towards or away from threshold? Towards If we allow chloride (negative charge) to come in as we start having neurotransmitters bind to receptors which become channels, are we going to go towards to away from threshold? Away If ACh gets dumped on the skeletal muscle, is it excitatory or inhibitory? Excitatory If ACh binds at the heart at the SA node/pacemaker, is it excitatory or inhibitory? Inhibitory How can acetylcholine be excitatory and inhibitory? It's binding to a different receptor which is letting in a different ion The inside of the cell is what charge compared to the outside? Negative
What are integral proteins? Proteins that are found within the cell membrane What are the big 4 integral proteins? Channels, carriers, pumps, receptors What are the 4 tissues? epithelial, connective, muscle, nervous What is the role of ATPase in spontaneity? non-spontaneous ((+) ΔG) —> spontaneous ((-) ΔG) Define the variables in the following equation: ΔG = ΔG - T(ΔS) ΔG = change in free energy ΔH = change in enthalpy ΔS = change in entropy How many sodium in? Potassium out? 3 Na+ out 2 K+ in Does sodium want in? Yes Does potassium want out? Yes What 2 proteins allow for the RMP of a cell? Na+/K+ "ATPase" Pump and "Slow Leak" K+ Channel What is entropy? a state of disorder (the state of disorder in systems goes up) How do we reverse the state of disorder going up? We start putting energy in the system to make reactions that don't want to happen, happen Voltage gated channels can open/close at a specific mV due to "gates". What are "gates"? A few amino acids that can "hinge"
What does it mean when we are looking at the muscle proper? We are looking at the entire muscle Macro —> Micro Muscle (proper) —> Fascicle —> one muscle cell/myofiber/myocyte —> Myofibrils —> Actin Myo means Muscle Sarco means Flesh How many myofibrils are in each muscle fiber? There is a genetic component Actin is a _____ filament thin Myosin is the _________ filament thick Troponin binds Calcium When we want to contract a muscle cell, what is the organelle that has sequestered the calcium? Sarcoplasmic reticulum How does the action potential get deep? T-tubule Myosin is short for Myosin ATPase What can bind to the head of myosin? ATP What detaches the head from actin? The binding of ATP to the myosin head Describe the steps of the muscle contraction cycle Calcium (from sarcoplasm reticulum) binds to troponin
Molecular interaction facilitates conformational change: Tropomyosin rolls out of the way and exposes myosin head binding sites.
- Cross bridge: Myosin heads lunge forward toward M line and bind
- (Assuming no energy, pH, or spatial limitations) Power stroke: Myosin heads are going to pull actin over the top
- Bind ATP in order to get the head to let go
- Hydrolyze to recock the myosin head What does it mean to hydrolyze ATP? ATP —> ADP + PO Muscle Contraction Cycle
- Calcium (from sarcoplasm reticulum) binds to troponin
- Molecular interaction facilitates conformational change: Tropomyosin rolls out of the way and exposes myosin head binding sites.
- Cross bridge: Myosin heads lunge forward toward M line and bind
- Power stroke: Myosin heads are going to pull actin over the top
- Bind ATP in order to get the head to let go
- Hydrolyze to revive the myosin head Which muscles are striated? skeletal and cardiac What is one sarcomere? Z line to Z line H band is the length of The end of one actin to the beginning of the next actin A band is the length of myosin (thick filament) I band is the length of The end of one myosin to the beginning of the next myosin What causes the striation in muscles? A (dark) band and I (light) band
What molecule is allowed in a Nicotinic ACh Channel? Sodium What molecules are allowed in/out of a Muscarinic ACh Channel? Chlorine In Potassium Out Where are most Nicotinic ACh Receptors found? Skeletal muscle Where are most Muscarinic ACh receptors found? Cardiac muscle is the vagus nerve sympathetic or parasympathetic? parasympathetic Does an IPSP slow down or speed up heart rate? Slow down If we allowed our heart beat to be at rest, what would the heart rate be? 2 beats per second 120 beats per minute (Too much) What are the possible fates of NT?
- Diffuses out of the synapse & are grabbed by astrocytes (a type of glial cell)
- Enzymatic Degradation: acetylcholinesterase (breaks down acetylcholine)
- Reuptake protein (on the presynatpic side) Ogliocytes Myelination of CNS Schwann cells produce myelin in PNS ependymal cells Produce cerebral spinal fluid What drug inhibits the serotonin reuptake protien? Selective Serotonin Reuptake Inhibitor (serotonin levels go up) (antidepressants) Selective serotonin reuptake inhibitors are legal. What is illegal? serotonin reuptake inhibitors (methamphetamine)
What happens when the active site of acteylcholinesterase is blocked by Sarin Nerve Gas, a competitive inhibitor? ACh numbers go up which continue to bind to Nicotinic Receptors that are disproportionately found in skeletal muscle (EPSP). Skeletal muscle activity goes up What is it called when skeletal muscle hits a maximum state of contraction and stays there? Tetany What are some of the dangers of tetany? Bones break Diaphragm locks up/no movement = no O2 (ventilation) What happens if the myosin heads do not detach? Alive: cramp Dead: rigor mortis What is the first energy source used in muscles? Creatine Is muscle swelling due to supplemented creatine true muscle building? No, muscle swells because creatine goes into muscle and is followed by water How much of our CO2 is in the blood buffer system? 75% CO2 and pH are inversely proportional (Ex. Working out: CO2 levels go up, H levels go up, pH goes down, medulla picks it up, respiration/heart rate go up) Where is carbonic anhydrase found? red blood cells and the kidney The pre capillary sphincter is under ______ control Adrenergic The postganglionic NT of the sympathetic nervous system is Norepinephrine
When lactate is shuttled into the mitochondria it is said to be Intracellular When lactate acid goes into the blood and to another tissue it is said to be Intercellular What is gluconeogenesis? The reverse of glycolysis (pyruvayte => glucose) What 3 things can happen to pyruvate in the liver?
- Glucogenesis
- Krebs cycle
- Back to blood What is the storage form of glucose in our body? glycogen What can store glycogen? Liver and skeletal muscle How is the liver different from skeletal muscle in regards to glycogen storage? The liver has the ability to break down glycogen into glucose and ship it into the bloodstream When is muscle soreness felt after intense muscle exercise? 24 - 36 hrs after (microtears) If we have microtears, what is the response? Inflammation/Pressure/Pain (rebuild & repair) How does our body respond to pain from inflammation? "Let us repair/let tissues heal" What happens to testosterone levels after a workout? Levels go up in both male and female because it's very good at repairing skeletal muscle which is done via satellite stem cell recruitment What do satellite stem cells do? Why is it important? Satellite stem cells donate nuclei to skeletal muscle cells which lead to more transcription/translation of gene for actin and myosin What is the difference between "fake" muscle building and true muscle building?
"Fake" muscle building => swelling of muscles as a result of bloating from creatine supplements True muscle building => involves muscle tears, soreness 24-36 hrs after, donation of nuclei to muscle cell What are the three types of muscle soreness?
- Burn => pH levels go down
- Muscle soreness 24-36 hrs after/microtears
- Tendons/ligaments => prolonged extension of muscles => soreness for a month What does ATP Hydrolysis do? Makes reactions that normally wouldn't happen, happen ATP —> ADP + PO Na wants in but the ATPase Na/K pumps Na out. How? ATP Hydrolysis (makes things that naturally don't want to happen, happen) What is the threshold for skeletal muscle AP? Neuron AP? Skeletal muscle: - 50/-55 mV Neuron: - 50/-55 mV What is the RMP of skeletal muscle? Neuron? Skeletal muscle: - 90 mV Neuron: - 70 mV At what voltage do VG Sodium Channels close in skeletal muscle? Neuron? Skeletal muscle: +40 mV Neuron: +30 mV What are the three muscle fiber types? Type I (slow/marathon runners), Type IIa, Type IIb(fastest/mitochondria/sprinters) What are the two proteins associated with RMP? Na/K ATPase Pump Slow Leak K Channel What channel is associated with depolarization? voltage gated Na+
Hematopoesis Skeletal muscle What happens when there's an increase in hematopoiesis? Increase blood cells, especially in the red marrow cavities of flat bones (long bone/young); under the influence of erythropoietin (EPO) from the kidney What disorder is associated with diminished growth hormone? Dwarfism What disorders are associated with too much growth hormone?
- Acromegaly (Adenoma): before epiphyseal plates have fused
- Gigantism: after epiphyseal plates have fused What is adenoma? a benign tumor formed from glandular structures in epithelial tissue secreting from a cell can be:
- Autocrine: effect on same cell it was secreted from
- Paracrine: effect on cell near by
- Endocrine: hormone into the blood stream (islets of langerhans) What type of cells do islets of langerhorns have? alpha: glucagon => B.S. up beta: insulin's => B.S. down gamma: somatostatin <=> GI process What 4 hormones fix hypoglycemia? All raise blood sugar Glucagon, cortisol, growth hormone, epinephrine (adrenaline) What is the only hormone that lowers blood glucose? insulin hypoglycemia low blood sugar hyperglycemia high blood sugar what does low insulin lead to? high blood sugar => diabetes (sugar in the urine)
There can be a problem with insulin and/or insulin receptors What happens when diabetes goes untreated for a long period of time? crystallize the sugar which blocks blood flow, for example, in the leg => no O2 => necrosis => amputation What happens when someone has hypoglycemia? short-term effects: RBCs Liver Brain Need to be addressed by 4 hormones Is the brain in the short term more concerned about low blood sugar or elevated blood sugar? low blood sugar (brain) "Starch it up" What does insulin bind to? tyrosine kinase receptor What happens when insulin binds to tyrosine kinase receptor? phosphorylation, causes a cascade of events which regulate GLUT4 which allows glucose into the cell Diabetes Type ___ is congenital I Vagus Neve X is _______________ to the sino atrial node which _______________ heart rates Parasympathetic; lowers Thanks to the vagus nerve, heart rate goes from beating every ____ secs to every ___ secs 0.5, 0. Describe a cardiacs muscle AP refractory period
