vertebrate physiology final

How does the system reset (nerves)

releasing acetylcholinesterase to break acetylcholine into two parts, and a carrier carries the two parts into presynaptic cell to reassemble acetylcholine and reload vesicles. to get ready for the next signal.

explain the molecular basis of red blood in the red blooded arctic fish

red blood contains hemoglobin, a protein that holds onto iron which then is able to cary oxygen throughout the body. the iron within the hemoglobin gives blood its red color.

after -50 mv, after action potential___

-K+ leak channels still open and flowing K+ in and out and Na+/K+ ATPase pump still open and pumping 3 Na+ out and 2 K+ in. -Voltage gated Na+ channels close at the inactivation gate so that the region is unable to depolarize (refractory period), until then K+ continues to rush out and hyperpolarizes until inactivation gate opens .-Voltage gated K+ channels open when membrane potential is depolarized to +30 to release K+ out of cell and repolarize to resting membrane potential. So, K+ rushes out of cell to polarize the cell to -70 mv. While K+ leak channels are open and allowing K+ to flow in and out, voltage gated K+ channels are needed to push more K+ out of cell to polarize the cell back to resting membrane potential faster to be ready to respond to the next signal. -then ion channels return to their resting potential state and cell returns to -70 mv.

difference between steady state and non steady state

-presence or absence of O2. -Steady state is taking in oxygen from environment (aerobic), and make energy that we need as fast as we use it. It does not require using our stores, we make energy and use it as quiclly as we make it. Making energy through glycolysis, krebs cycle, ETC, and oxidative phosphorylation. we dont require using myoglobin, phosphagens, glycogen stores, etc. If we are using energy as fast as we are making it and not using stores of oxygen or energy production, then there is O2 in environment . Steady state also means that any byproducts that we are producing are not building up, so LDH is functioning when oxygen is around, its just sitting there but nothing is building up so not catalyzed. system is not being pushed to one extreme or another, energy is used as fast as we make it. So, cell remains constant in level of ATP and byproduct formation, can go on and on forever without limitations. *aerobic respiration is sufficient to make all ATP necessary. -Non steady state- anaerobic, bc aerobic state not sufficient enough to make all ATP necessary. have to use emergency back up stores in the body to make energy, depletes stores, and leads to a buildup of byproducts. ex: build up of lactic acid bc LDH is being used to convert pyruvic acid to lactic acid, depletion of mypglobin stores of oxygen, depleting the phosphagen stores so creatine building up (bc now all phosphate removed from creratine phosphate to make ATP), so byproducts of making energy is going to build up faster. cannot persist for long.-eventually, when back to steady and oxygen state, will lose byproducts and replenish our stores.

specialized eye-lens crystallin proteins

-some organisms have the same crystallin protein in their lenses that are the same protein but do not function the same at different temperatures. For example, antarctic fish lenses are clear at a temperature of -2 degrees celsis, but a cow lens in the same temperature would cause cold induced cataracts as the protein denatures at that temperature and become opaque, and light wont be able to pass through. So, while thei have the same protein , there are small nucleotide changes that were selected for over evolutionary change that allow the toothfish protein to not denature at -2 degrees celsius compared to the cow's. -in other words, the proteins evolved to function at optimal temperature for organisms, same crystalin protein for every organism, but with small nucleotide changes that allow protein to function and not denature at certain temperatures.

central dogma

DNA is "read" by RNA polymerase by makeing an RNA copy by looking at DNA and making an mRNA version of it. Then the mRNA is sent to the ribosomes outside of the nucleus, and the ribosomes read mRNA and translate it into protein. The protein then builds the organism, and we see than and call it a phenotype (exL how much lactate dehydrogenase expressed, bigger heart, missing hemoglobin gene).

Sometimes an organism must warm only a certain part of their body. what is this type ofthermoregulation called?

regional heterothermy

Describe how temperature in the Pejus range can lead to extinction of a species

In the pejus range, proteins are not functioning optimally. So, this can slow down an organisms biological processes to the point that the organism may not reach mature age to reproduce or it can be so slow that predators can easily catch it. So, as organisms in the pejus range can't reach maturity to reproduce and are so slow they are caught, the species will eventually become extinct.

In class we discussed how lizards and fish, bass and trout, change their metabolic rate in response to a chronic change in temperature. In general, lizards and fish, have a higher metabolic rate at colder temperatures. Why?

Initially, as organisms move to a colder temperature, its metabolic rate decreases as its molecules move slower at a colder temperature, this would be an acute change. however, as the organism remains in the colder environment, its metabolic rate increases to acclimate to this new temperature, bc if it did not acclimate, its MR would not be optimal to that temp. and the organism would die.

Describe the types of energy we mentioned in class. Can they all do work? GIve an example of how one type of energy is used in an example from class.

Mechanical: energy in movement of something in a physical space, it can do work electrical: energy in the movement of ions across a cell membrane, down its concentration gradient. it can do work. chemical: energy in covalent bonds, this energy is totipotent, meaning it can be used to do all forms of work so sets up mechanical and electrical energy. heat: byproduct of chemical reaction, can be used by an organism to thermoregulate but cannot do work. example: sodium rushing into cell and depolarizing the membrane potential is an example of electrical energy. also, muscles contracting to move skeleton and grab something is mechanical energy.

Describe how the heterothermy of the sphynx moth is established and why?

Sphynx moths thermoregulate their flight muscles, but for the rest of their body, they are poikilotherms, meaning the rest of the body is always at ambient temperature. they are thermoregulating poikilotherms. To fly, sphynx moths flight muscles must be at a specific temperature (35 degrees celsius). To thermoregulate and reach that temperature, the moth has to do a "pre-flight" warm up, which is when the moth contracts the muscles that drive its wings up and the muscles that drive its wings down both simultaneously. This causes the wings to not move, but it does make the moth vibrate, which looks like it is "shivering", the wings wont move bc both flight muscles are contracting. So, to warm up flight muscles, first, the moth's tubules deliver more oxygen, which is required for the moth to make more ATP for muscles to contract, as the muscles contract, they create heat as a byproduct, warming up the flight muscles. The heat around their flight muscles is then trapped by the moth's fur like scales, and the rest of the body remains at ambient temperature. After their flight muscles reach 35 degrees celsius and the heat is trapped by the fur like scales, the moth can take off to fly. -sphynx moths are temporal heterotherms (difference over time) when not flying their flight muscles are cold and when they are flying they are warm. -sphynx moths are also regional heterotherms (difference over space) as their flight muscles are warm while the rest of the body is ambient temperature.

How is the action potential propagated down the axon of that neuron

The Na_ diffuses down the cell body, and as it is diffusing down, it is depolarizing the membrane potentials from -50mv to +50 mv along the way, and propagating the action potential. this continues down until the axon terminal is reached.

describe two physiological attributes of the cray fish tail that allow it to escape a predator, or bolt, quickly

The crayfish has fast glycolytic muscles which utilize non-steady state mechanisms of energy production. The crayfish also has electrical synapses in its cells. So, when the crayfish is running away from a predator and depletes its oxygen, it can utilize nonsteady mechanisms of energy production such as using LDH to convert pyruvic acid and NADH to lactic acid and NAD+ to run anaerobic glycolysis, taking glucose from glycogen stores to also use in anaerobic glycolysis, and using creatine kinase to take a phosphate off of creatine phosphate to place on ADP and make ATP. The crayfish's electrical synapses allow sodium to diffuse directly into the next nerve cell or muscle cell as their cytoplasms are directly connected by gap junction, so does not need neurotransmitter, allowing sodium to diffuse right through and propagate an action potential. These physiological attributes allow the crayfish to have burst of energy in tail and to run away quickly.

describe how nerve cells communicate in the crayfish to allow it to escape from a predator

The crayfish's nerve cells have electrical synapses, meaning their cytoplasms are connected and sodium can rush directly between then, making the propagation of action potential very rapid. Thus, the signal travels down nerve cell and into muscle cell to allow the crayfish to flee is very rapid. have electrical synapses, so electrical current moves directly through cells, based on diffusion of sodium from one cell to next. So action potential propagates very fast in comparison to chemical synapses which require influx of calcium, release of neurotransmitter, binding of neurotranmitter and release of Na+ to depolarize. cytoplasms of nerve cells are connected through gap junction, so electrical current directly travels from one cell to another as sodium diffuses directly down to next cell, propagating action potential. No need for neurotransmitter.

monitor lizard is a poikilothermic "cold blooded" meaning that it will use the heat of the sun to aide in its digestion. draw, label, and describe a graph that illustrated what happens to the lizard's stomach temperature as it suns itself. how do we describe this type of regulation?

The graph should have an X axis of "external temo from sun: and y axis of "lizard stomach temp" and it should be a positive linear line. this is an example of conformity, meaning as the external temp rises, the lizards internal temp also rises as it conforms to the temperature.

While on vacation, you decide to visit some hot springs, but you are unsure which spring is most comfortable. Describe how you will sense the temperature of the water as you test it with your finger. How is the action potential initiated in the neuron of your finger

The heat stimulus opens thermoreceptors channels, allow Na+ to flow into cell, this depolarizes the membrane potential from resting potential of -70 mv to -50 mv, at -50 mv, voltage gated Na+ channels open, letting more Na+ in and depolarizing membrane potential to +50 mv, the depolarization from -50 mv to +50 mv initiates the action potential.

Given that the external physiology of the leopard frog and the western toad is very similar, why is the leopard frog able to jump so much farther than the western toad when both are escaping a predator.

The leopard frog expressed more LDH, thus it makes more of the enzyme than the western toad. The LDH enzyme allows for the leopard from to make ATP in times of no O2. for example, if the leopard from is running from predators and is out of breath, instead of needing to rest, like the western frog will likely need to do, it is able to continue jumping as the enzyme LDH is able to convert pyruvic acid and NADH to lactic acid and NAD+, and the NAD+ allows for glycolysis to continue running and generating more ATP for energy. So, the leopard from does not get as tired as the toad and is able to jump farther.

Int he context of a fox pursing a pheasant, speed is of great importance to ensure the survival of the next generation. Explain how the physiology of the pheasant escaping the fox provides speed to help its offspring escape a fox in the future

The physiology of a pheasant, whether it be muscle mass, wing span, or a bigger heart, are traits that are able to be passed on via the pheasants genes. These genes that code for the proteins that generate the phenotype that is advantageous for survival can be inherited by the pheasant's offspring. only pheasants who survive long enough and escape from foxes to have a chance to reproduce will be able to pass on their advantageous genes, increasing the frequency of these genes in the next generation as pheasants mate with other pheasants who also escape.

In class we discussed the energy cost of transport. while body weight is a significant factor of the cost, what was the primary characteristic that determined how much energy is required for an animal to move itself around, i.e locomotion. Give an example.

The primary characteristic that determined cost of transport was the mechanism of locomotion; including walking, swimming, or flight. For example, walking costs more than swimming. So, a shrimp has a higher cost of transport than a dolphin, even if they live in the same environment, because the shrimp uses walking as type of locomotion, which costs more than swimming.

as we watch ruminants like the cow eat, we see them consume primarily grass. however, as scientists, we know that cows do not have the gene to make the protein cellulase, necessary to digest the cellulose in grass. additionally, we know that cows get little nutrition directly from the gradd. what is the primary source of protein in the cows diet that it ises to produce its own muscles?

The rumen of the cow contains bacteria which do have cellulase to break doen the frass. as the cow eats grass, it is feeding the basteria. these basteria overflow into the cows "true stomach" and are then digested, acting as the cow's primary protein souse. not all of the basteria are digested and some stay in the rumen to continue to proliferate throughout the cow's life.

now initiated action potential at cell body and now needs to move down cell body and down axon. what intiiates next axon potential, 2 steps down the axon? -so propagation of action potential:

The sodium ions slowly diffuse down cell body and change the membrane potential of different points as they move down, leading to a change of membrane potential in areas to -50mv leading to a propagation of the action potenital, opening the voltage gated Na+ channels in that area and letting Na+ move in, and the cycle continues down to the terminal. propagation is sodium diffusing down cell body and causing membrane potential change at different parts of axon, all the way down to axon terminal. -the points passed the cell body have everything but mechanoreceptors.

Describe in detail how and why the sphync moth accomplishes this task of regional heterothermy (warming a certain part of its body)?

The sphynx moth lives in ambient temp of 20 degrees, but it can only fly if its wing muscles are at 32 degrees. so, to heat its wing muscles, the moth does a "pre flight warm up". The moth takes in oxygen from tubules to make ATP for energy, the moth then uses that energy to contract its up and down flight muscles simultaneously, which causes the moth's body to "shiver" while it's wings don't move. The byproduct of this is heat, which is then trapped at the moth's flight muscles by fur like scaled that the moth has, and this allows the moth to fly.

What happens when the action potential reaches the axon terminal and how does that cause communication between that cell and a muscle cell

The voltage gated Ca+ channels open, and ca+ comes in. the ca+ binds to membrane vessicles, causing the vesicles to fuse with the cell membrane and releasing acetylcholine, that was inside of the vesicles, into the synaptic cleft. The acetylcholine (neurotransmitter) then binds to acetylcholine receptors and opens ligand gated channel, releasing Na+ into the cell. The Na+ will then depolarize the cell membrane potential, leading to an action potential, and the communication will continue.

Why are amino acids like histidine, considered essential amino acids?

They are considered essential amino acids because the body needs them to survive (use in biological processes), but the body is unable to make them on its own. Instead, the essential amino acids must be consumed.

Describe the primary mechanism these cells (fast glycolytic) use to produce ATP

They use nonsteady forms of energy production as aerobic respiration is not sufficient to produce all ATP necessary. So, they utilize the stores for ATP. They use LDH to convert pyruvic acid and NADH to lactic acid and NAD+ to run anaerobic glycolysis, and they use creatine kinase to take a phosphate off off creatine phosphate and onto ADP for ATP production (substrate level phosphorylation)

consuming oxygen is necessary to make energy. How do we describe the maximum rate of oxygen consumption?

VO2 max

Describe how cone snail venom allows it to catch the fish, be sure to discuss the molecular interaction int he fish

a fish must be able to contract its muscles to swim away. for a muscle to contract, the neurotransmitter acetylcholine must be able to bind to the acetylcholine receptors to allow the channels to open and influx ions to allow for a muscle contraction. What the snail does, is it released a poisonous harpoon when the fish is near, and the harpoon injects the protein alpha conotoxin, this protein blocks the acetylcholine receptors, not allowing acetylcholine to bind, and thus the fish is unable to contract its muscles to flee. thus the snail paralyzes the fish and is able to engulf it.

Describe how an action potential occurs. Start from a cell at resting membrane potential and describe what happens. (class)

action potential occurs when a stimulus opens the receptor proteins on the outside of the cell, letting sodium rush into the cell, this lead to depolarization of membrane potential from -70 mv to -50 mv, once membrane potential is at -50 ( reaching threshhold) it causes an all or nothing initiation of an action potential and all voltage gated Na+ channels opens and more Na+ ions rush in, making the membrane potential depolarize to +50.

transmission of nerve cell to muscle cell step

action potential reaches the axon terminal and voltage gated Ca+ channels open. The calcium rushes in and binds to proteins on surface of vesicles, which are full of the neurotransmitter acetylcholine. This causes the vesicles to fuse with the cell membrane, becoming one, and release acetylcholine into the synaptic cleft. The acetylcholine then binds to the acetylcholine receptor, opening the ligand gated channel and letting Na+, depolarizing the membrane potential to -50 mv and causing an action potential.

poikilotherms must survive different durations of temperature change: acute, chronic, and evolutionary. describe the three durations of temperature change.

acute: a brief change in temperature, like one sunny da, that causes a rapid physiological change in organism. chronic: an elongated change in temperature, like 3-5 months, that causes the organism's biological processes, like BME, to acclimate to that temperature. evolutionary: a permanent change in temperarture, like an organism moving to a new habitat with a different temperature. Genes to adapt to that new temperature are selected for as generations go by.

all of thesefish have a genetic change that allow them to live in water cold enough to freeze solid. explain that genetic change and how this change keeps the fish from freezing alive.

arctic fish contain antifreeze proteins that allow the fish to survive in freezing water without freezing. These proteins bind to nucleating ice within their blood and prevents it from growing or spreading.

describe what the following graph is showing and one conclusion you can draw from the data.

as habitat temp increases, the overall percentage of unsaturated hydrocarbons in different species decreases. this shows that at colder temprature, fish need more unsaturated hydrocarbons in order to ensure their cellular membranes remain fluid and dont freeze. this is because unsaturated hydrocarbons have more double bonds and thus are less tightlt packed, making them more fluid.

why does propagation only go one way?

bc inactivation gates on voltage gated Na+ are closed, so in refractory period. so either sodium cant create action potential bc refractory or hyperpolarized and will take lots of sodium to get to -50. -so bc of activation gates and hyperpolarization is cnecessary to move in one direction, down cell body all the way to terminus and not back up the cell body.

why are ice fish and red-blooded antarctic fish hearts still red?

bc they have a myoglobin gene, which is a protein found in muscles, that holds on to iron and holds on to O2 in tyhe muscles, like the heart. So, even tho blood can't transport O2, the heard has its own protein that can hold on to iron and store O2 in the heart.

fish with less hemoglobin have bigger hearts, why?

because they are pumping a low concentration of O2 but faster, so O2 is getting to the heart faster, so the heart needs to be bigger to pump blood faster. However, both fish get the same amount of O2 because other fish carry O2 in all cells while ice fish cant carry high conc of O2 in blood. so while it pumps faster, the other is pumping more.

how did crystalin proteins evolve:

how did crystalin proteins evolve:

explain how cattle raising tribes in africa synthesize enzyme to digest milk

certain tribes that live with their animals consume lactose all the time. So amongst that population, if a mutation existed where that individual could drink lactose and receive nutrients more readily and did not need to forage for it, they survived due to selective advantage. Then they reproduced, and the mutation spread amongst the population, it was selected for.-there is mutation in human pop. where people can comsume lactose throughtout their wholelife.-assumed that mutation in introl caused the gene to be expressed improperly leading to lactase bein gexpressed. The enhancer is there to turn the lactase gene on.-so mutant intron causes lactase gene to be continually expressed, and enhancer is present to turn the gene on and lactase is expressed.

what allows polarization

closing of inactivation channel, opening voltage gated K+ channels, sodium potasium ATPase pump, and K+ leak channels. leads to net negative inside, so polarize

example of acute, chronic, and evolutionary change

example: antarctic fish selected for adaptations that better fit their colder habitat as generations moved to colder and colder temperatures, one being the ability for crystallin proteins in the eyes to not denature at -2 degrees celsiu. example: lizards that were moved from 33 degrees celsius to 16 degrees celsius rapidly showed a significant decrease in their MR as they adjust (since cant regulate Body temp) as they moved to a colder environment so all their biological processes slow down as molecules are slowed down at a colder temperature, so less likely to find eachother bc they are moving around more slowly. This is acute change. If lizard left there, it will acclimate to the optimal MR for 16 degrees celsius because it is not sustainable if the lizard does not acclimate, it would die

A sprinter who has competed in the 100 and 200 meter sprint for 10 years has decided to start running marathons, 26.2 miles instead. Name the muscle fibers that are abundant in the sprinter today, before she starts running long distance races.

fast glycolytic

describe the characteristics of FG and SO. How does their physical characteristics help meet the organism's physiological needs?

fast glycolytic: fast glycolytic are more white muscle fibers than red. They have high LDH expression, low myoglobin (bc won't use the oxygen in store), low mitochondria (rely on non-steady mechanisms of energy production that do not require mitochondria, dont' rely on CAC and ETC for ATP production), low capilaries (don't need to carry as much O2 bc won't use it), and large glycogen store and all this is necessary because fast glycolytic muscle fibers are fast twitch and correlate to a burst and "fast" non-steady state, such as organisms sprinting away from predators. They use non-steady state mechanisms of energy production such as using LDH to covert pyuvic acid and NADH r=to lactic acid and NAD+ to run glycolysis and make ATP, using creating kinase, which transfers phosphate from creatine phosphate to ADP to make ATP, or using the glycogen stores for glycolysis to make energy. *can operate even if O2 is around but don't require oxygen. they do have ETC and mitochondria and have myoglobin just don't need as much bc not primary form of energy production. \ Slow oxidative: More red muscle fibers than white. They have low LDH expression (do not rely on non-steady forms of energy production mechanisms), more myoglobin (bc use O2 for energy production, as final electron acceptor), more mitochondria (bc rely on ETC for energy production, which takes place in mitochondria), high capillaries (to carry more O2 in blood), and low glycogen stores. This is necessary bc SO muscle fibers are slow twitch and used for endurance, long distance running, so the organisms are in a steady state and are able to use O2 from their environment to make energy as quickly as it is used. They utilize steady state mechanisms of energy production and primarily make ATP through the ETC so require oxygen.

What type of muscle fibers will she have after she has been running marathons for 10 years. How do these cells predominantly make ATP and how are they optimized for this type of energy production

fast/slow oxidative. These muscle fibers utilize aerobic/steady forms of energy production as aerobic respiration is sufficient to make all ATP necessary. These cells primarily make ATP in the ETC through oxidative phosphorylation and through aerobic glycolysis.,they use oxygen in the environment to make energy as fast as its used, so it is sustainable. These cells have high myoglobin, to store more O2 in case it is needed, high mitochondria as ETC is in mitochondria so need mitochondria to make energy, and high capilaries to carry more O2 in the blood. These traits optimize cells for this type of energy production. The cells have low LDH and glycogen as they do not utilize stores as their main form of energy production, so they do not have a build up of byproducts.

what does express/expression mean

protein is being made from that DNA. So copy of that DNA is made into mRNA and it is going out into cytosol where ribosome translate to protein.-so protein made from that gene int hat cell and it is necessary

humans did not evolve a mechanism to create a molecule that would allow them to collect light to see, instead tehy evolved a mechanism to use a light collecting molecule they consume as part of their diet. explain

humans do not have a light collecting mechanism that we are able to synthesize ourselves. instead, we ingest photosynthetic plants that contain vitmain A, which has retinol. retinol absorbs light. So, we take the retinol from the vitamin A and we make a protein that can hold on to the retinol to help us absorb light and see.

explain why the white blooded arctic fish does not have red blood.

ice fish do not have the protein hemoglobin, which carries iron and thus oxygen through blood, iron is what gives blood its red color, thus ice fish do not have that as they have no capability of carrying iron through the blood without hemoglobin. Moleculary, ice fish are missing exon 1 and 2 of alpha globin, and have no beta globin gene, and this have no hemoglobin to hold onto iron.

Poikilotherms can thermoregulate by behaving a certain way. Describe how lizards maintain their body temperature this way. What is this type of thermoregulation called?

lizards are behavioral thermoregulators, and they are ectotherms, meaning they conform to ambient temperature. so, lizards maintain their body temperature by moving in and out of the sun as needed. They even sometimes just place parts of their body in the sun because that is the area that need maintaining. So, lizards use basking in the sun as a way to maintain body temperature. This thermoregulation is called behavioral thermoregulation.

What physiological changes have been seen to occur in the fish (from prior question) to allow for the metabolic acclimation to cold temperatures?

more mitochondria and an increased activity of enzymes involved in the ETC, like cytochrome oxidase. this allows the fish to make more energy in the ETC, as it will need energy to acclimate to cold temperature.

Why does ACTH not activate milliomns of other cells that it bounces into on its way to the adrenal gland on the top of the kidney?

on cell membranes, only the receptors that a specific cell needs are expressed, making a cell only responsive to signals that match its own receptors. in this scenario, onlt the adrenal gland cells have the receptors to respond to ACTH and the cells along the way do not, so they are not activated.

describe how the physiological attributes of the pronghorn sheep allow it to have a much higher maximum rate of oxygen consumption than a dog of the same size?

pronghorn sheep have larger lungs, allowing it to take in more oxygen, more myoglobin per muscle cell, allowing it to store more O2 in the muscles, more mitochondria per cell, allowing it to make more energy through oxidative phosphorylation in the ETC, more capillaries, allowing it to move more blood per surface area, thus moving more O2 (as O2 is held by iron in the blood) to cells, and has a larger heart to pump a larger volume of blood, and thus more oxygen.

as we watch ruminants like the cow eat, we see them consume primarily grass. however, as scientists, we know that cows do not have the gene to make the protein cellulase, necessary to digest the cellulose in grass. additionally, we know that cows get little nutrition directly from the gradd. so what direct nutrients to cows get from the f=sigestion of grass

short chain fatty acids

List the general types of epithelial cell arrangements, the structure of the epithelium they create and how this structure is uniquely suited to the general function of the epithelium.

simple epithelium are a single layer of cells, consisting of either squamous (flat), cuboidal (cube), or columnar (rectangle) cells. Because it has a single layer, it is best suited for absorption of essentials (oxygen and nutrients) and secretion, thus it is likely found in the intestines. stratified epithelia are multiple layers of cells (2 or more), also squamous, cuboidal, or columnar. Since they have more layers of cells, they function more as protection and formation of boundaries, thus found in areas like the skin.

how to get from -70 to -50 mv

some type of receptor is activiated by some stimulus, could be mechanoreceptor. if mechanoreceptor stimulated, will open channel that allows sodium to come in. The influx of sodium will depolarize membrane potential from -70 to -50 mv. Then, reach threshhold, and all volatage gated Na+ channels will open in that area and we get an action potential. However, system has to be finely regulated to initiate action potential and tell next tell next cell what to do (propagation) and reset system quickly. So, we also have K+ leak channels and Voltage gated K+ channels. The K+ leak channel allows potassium to move through at all times and "fine tuning" to resting membrane potential, unless sodium rushes in. the voltage gated K+ channel purpose is to repolarize.

How do bobtail squid and vibrio bacteria work together to survive long enough to reproduce.

the bacteria enter squid cavity and destroy its cells for space , but cells release neutralizing agent that prevents bacteria from destroyign any more cells. The bacteria remain in the cavity and reproduce. when enough bacteria have reproduced, the emit a biolumiescent light that is able to hide the squid's shadow from predators at night. in the morning, the squid releases some bacteria so that the bacteria left can reproduce and emit a light by the time night time occurs. So its a symbiotic relationship when bacteria get mobility and the squid protection from predators.

draw, label, and describe a graph illustrating how the Ph of the monitor lizard's srtomach does not change as it suns itself. how do we describe this type of regulation

thegraph should show an x axis of "external ph" and a y axis of "lizard stomach ph". the graph should show a straigh line that does not decrease or increase. As the external ph in the lizards env rises, the lizard;s stomach ph remains the same as this is an example of regulation.

explain the relationship of unsaturated bonds of the phospholipid tails

unsaturated bonds have a double bond which create a bend in the tail, which prevents tight packing of the tails and causes freedom to move. a good example is olive oil. However, saturated bonds means all bonds are taking up the carbon and hydrogens and the tails are all tightly packed so there is no room to move, good example is solid butter. The membrane, which has a lot of proteins that need to move around, would want some unsaturated bonds in it instead of all saturated. Thhis is so that signals, channel proteins, and other proteins can move around. We would want channel proteins to move to other areas of the cell to let other things outside of cell on different side in. so want a fluid mosaic model.