Exam 1 ASI 533

What are examples of positive feedforward?

-A hormone binds to its receptor on the cell surface, causing the activation of protein A inside the cell. Protein A activates Protein B, which then travels to the nucleus and increases production of mRNA for production of Protein L -In the immune system, proteins called Complement Factors are produced such that Complement Factor 1 activates Complement Factor 2, which activates Complement Factor 3 and so on down the line. The production of this series of Complement Factors ultimately causes large holes to form in the target cell membrane and the cell dies as a result.

What are examples of regulated variable?

-Body temperature -Blood glucose -Blood CO2

Examples of permissive feedback:

-Body temperature increases and metabolic reactions are reduced to decrease heat production -Body water increases and physiological responses decrease thirst and drinking behavior -Body water decreases and more water is conserved by the kidneys to return water to the blood and reduce urine volume

Hair:

-Contains keratin -Is formed from dead cells that originally arose from stem (germ) cells within the dermal portion of the follicle

What are examples of permissive feedback:

-Decreasing uptake of calcium from the diet in response to hypercalcemia -Sending less blood flow to the skin in response to hypothermia

Describe negative feedback of a regulated variable

-Dehydration occurs and thirst is triggered and the animal begins to drink. -Carbon dioxide begins to increase in the blood, respiratory rate increases and more carbon dioxide is removed from the blood and put into the surrounding atmosphere

a cell would have a gene in the nucleus and what would be synthesized in response to some physiological need or homeostatic response:

-Enzymes that convert cholesterol to precursors of estradiol -Membrane proteins that might be involved in moving substances through the cell membrane -Structural proteins that help cells move molecules throughout their cytoplasm

The cell membrane of a beta-islet cell of the pancreas should contain:

-Glut-2 or Glut-1 transporters -Should be made up of two layers of lipid molecules, oriented such that the hydrophilic parts face the extracellular and intracellular fluids

Examples of a controlled variable:

-Heart rate -Respiratory rate -Blood pressure

What examples of a controlled variable?

-Heart rate -Respiratory rate -Insulin secretion in response to elevated blood glucose -Secretion of glucagon in response to decreased glucose in the blood -The rate and amount of water filtered out of the blood by the kidneys

Describe negative feedback in general, and not just of a regulated variable.

-Heart rate increases during intense exercise, then is reduced after the exercise is over -Water is elevated in the blood, causing an increase in blood pressure. As a result, the kidneys excrete more water and water is lost from the blood -A muscle begins contracting and starts to build up heat. The heat causes a nearby artery to dilate and allow more blood flow to the muscle, which subsequently carries away more heat -Blood begins to leak out of a torn blood vessel. Clotting factors are activated and the tear in the blood vessel is sealed, resulting in no more blood loss

Examples of negative feedback

-Insulin increases due to increased blood glucose, resulting in a decrease in blood glucose and a decrease in secretion of insulin -Carbon dioxide in the blood begins to increase and the respiratory rate increases to remove more carbon dioxide from the blood

Example of simple diffusion

-Potassium ions moving through the extracellular fluid from an area where the solution is concentrated to an area where the solution is less concentrated -Glucose moving through the basal laminae of the small intestine and into the submucosa with its concentration gradient

ATP is required to:

-Produce enzymes that break down glycogen -Produce enzymes that convert glucose to either glycerol or fatty acids -Restore concentration gradients of sodium ions after repeated use of SGLT--1 -Create the cytoskeleton that allows an enterocyte to move Glut-2 vesicles from the basal to the apical membrane and back

What would could a cell do to reduce the chances of glucose leaving the cell as the concentration gradient reverses and glucose becomes higher on the inside of the cell than on the outside:

-Reduce the number of glucose transporters in its cell membrane -Prevent glucose from binding to glucose transporters within its cell membrane -Convert glucose to something that doesn't bind to the transporter protein on the intracellular face of the cell -Store the glucose as glycogen

Ambient temperatures above the upper critical temperature for dairy cows would likely result in:

-Relatively less ability to remove body heat through the skin -An increase in respiratory rate to try and remove more heat -An increase in the proportion of available energy being used for maintenance rather than milk production -A long-term acclimation that should increase the effective surface area by increasing the amount of capillaries within the skin -Greater numbers of afferent action potentials from warm receptors in the skin to the hypothalamus -Greater numbers of afferent action potentials from warm receptors in the large blood vessels in the thoracic and abdominal cavities to the hypothalamus

Insulin dependent cells:

-Should use Glut-4 as their glucose transporter -Will need to synthesize proteins to insert into their cell membranes, such as insulin receptors and glucose transporters -Can usually not take up glucose without insulin unless they are also partially insulin-independent like hepatocytes and skeletal muscle cells

Example of a regulated variable

-The amount of heat circulating in the blood -Glucose in the blood

A cell that has an intracellular solution of sodium chloride that is at 1% is placed in a sodium chloride solution that is at 2%. What is true about this statement?

-The cell could restore its original amount of water by bringing in more glucose through secondary active transport -Water will leave the cell via osmosis

What would help you to recognize that something is a regulated rather than a controlled variable?

-Usually circulates in the blood -Has sensors that provide instant or nearly instant information to regulatory systems about deviations in the amount -After a deviation they are regulated back to some physiological setpoint as soon as possible by physiological responses

If a cell had no ability to make cell membrane proteins it:

-Would not be able to respond to insulin -Would not be able to accomplish secondary active transport

Match the following: A. Regulated variable B. Controlled variable 1. Blood Calcium 2. Blood Pressure 3. Blood glucose 4. Blood Insulin 5. Intracellular calcium 6. Heart rate

1. Blood Calcium- Regulated 2. Blood Pressure- Controlled 3. Blood glucose- Regulated 4. Blood Insulin- Controlled 5. Intracellular calcium- None 6. Heart rate- Controlled

Controlled variables can be somewhat difficult to recognize. What would help recognize that something is a controlled rather than a regulated variable?

1. Can remain increased or decreased for prolonged periods of time without major adverse affects 2. Activity is controlled more by the physiological impacts of its activity rather than by a sensor that constantly monitors its activity 3. Regulates regulated variables

If the cell has only 10 active, fully functional sodium/potassium pumps in its cell membrane, how many ATP molecules would be required to bring 200 potassium ions into the cell? (Assume that potassium ion concentrations are in equilibrium at the start.)

100

The sodium/potassium pump is a primary active transporter that uses ATP to PUMP 3 molecules of sodium out and 2 molecules of potassium in. If the cell has 250 active, fully functional sodium/potassium pumps in its cell membrane, how many ATP molecules would be required to bring 200 potassium ions into the cell? (Assume that potassium ion concentrations are in equilibrium at the start.)

100

Assume that ATP is produced aerobically from glucose to yield 36 molecules of ATP/glucose. If an insulin-independent cell starts with 96 molecules of glucose inside and 120 molecules of glucose outside, how many of the glucose molecules will be used up in order to bring all 120 molecules of glucose into the cell and then restore any changes in concentration gradients of sodium afterwards?

2

After the drug from the previous question is removed, another drug is used to block the activity of the sodium-glucose symporter. How many ATP molecules would be required to return the concentration gradient of sodium to at least its original value (at least 200 outside and 10 inside)?

32

A cell has a concentration gradient of sodium across its membrane such that 200 molecules of sodium are outside and 10 are inside. The cell has 100 molecules of glucose inside and 90 outside. If the cell is treated with the drug Ouabain, which prevents the activity of the primary active transporters of sodium in the cell membrane, how many molecules of glucose can be brought into the cell?

47

Foods are high in omega 3 fatty acids, such as salmon or olives, are said to be "anti-inflammatory" while foods that are high in omega -6 fatty acids such as soybean or cottonseed opils are said to be "pro-inflammatory". Based on this, choose each of the following that should be true: A. Omega- 3 fatty acids should help to prevent or reduce conditions such as laminitis. B. Eating salmon is likely to cause an increase in symptoms associated with inflammatory bowel diseases such as Crohn's Disease. C. Sunburn might be worse in a fair skinned person who eats a lot of soybean oil as compared to an equally fair skinned person who eats a lot of olive oil. D. Cottonseed might be a good supplement for feeding horses during times of increased risk of laminitis.

A & C

Choose each of the following that would be true regarding insulin and glucose: A. During insulin resistance a positive feedback loop occurs because glucose remains high and continues to stimulate further insulin secretion B. Insulin is the hormone that is most responsible for converting excess carbohydrates into stored adipose tissue C. Insulin should serve to increase uptake of glucose in adipocytes and stimulate them to convert the glucose to triglycerides D. Insulin resistance is a permanent condition so really nothing can be done to recover -- all a person can ever hope for is to manage it with supplemental drugs and careful attention to the diet E. Excess insulin caused by hyperglycemia may cause a positive feedback response by stimulating gluconeogenesis in cells (particularly in the liver)

A, B, & C

The normal cell membrane: A. Should contain proteins if the cell is going to be capable of facilitated diffusion B. Should contain proteins if the cell is going to be capable of primary active transport C. Should contain proteins if the cell is going to be capable of secondary active transport D. Should be made up of two layers of lipid molecules, oriented such that the hydrophilic parts face the extracellular and intracellular fluids E. Should exclude calcium ions F. Should allow for simple diffusion of cholesterol G. Should allow for simple diffusion of Vitamin D H. Should allow for simple diffusion of glucose I. Should have the characteristics of a kind of viscous fluid

All except H.

A cell is frozen and then thawed out again, resulting in a few large holes in its membrane. Which of the following might you expect to change for the cell, assuming it survives and has no problems beyond losing the integrity of its membrane. A. It would no longer be able to make ATP from glucose B. Chloride ions would probably be in the same concentration in both the intracellular and extracellular fluids C. Assuming the cell had a larger concentration of sodium ions on the outside than on the inside, once the holes were formed more water would enter the cell than normal D. It would have more difficulty maintaining a concentration gradient where more sodium was outside the cell than inside E. It would use up a lot more energy in the form of ATP if it tried to maintain concentration gradients of ions between the extracellular and intracellular fluids F. Facilitated diffusion or active transport of cholesterol could no longer occur G. It should be able to take up glucose without using a protein carrier

B, D, E, G -Chloride ions would probably be in the same concentration in both the intracellular and extracellular fluids -It would have more difficulty maintaining a concentration gradient where more sodium was outside the cell than inside -It would use up a lot more energy in the form of ATP if it tried to maintain concentration gradients of ions between the extracellular and intracellular fluids -It should be able to take up glucose without using a protein carrier

A cell should be able to maintain a concentration gradient across its membrane of: A. Calcium B. Sodium C. Water D. Charged amino acids E. Glucose H. Vitamin D I. Cholesterol

Calcium, Sodium, Charged amino acids, Glucose

Pore or opening in membrane Allows for much greater movement

Channel

Increase, Decrease, or No Change. Result of reduced dietary sodium of the probable amount of Glut-4 glucose transport proteins in skeletal muscle cell membrane.

Decrease

What would a cell have difficulty creating and then maintaining a concentration gradient across its cell membrane?

Estradiol, Cholesterol, Vitamin D

Glucose moving from an area of higher concentration in the extracellular fluid to an area of lower concentration in the intracellular fluid is an example of:

Facilitated diffusion

Requires a concentration gradient to drive diffusion/movement Protein carrier to facilitate Movement across the membrane

Facilitated diffusion

True or False. Eating nothing but high fructose corn syrup should cause a rapid increase in stored glycogen in some cells but would have little to no impact on storage of triglycerides within white adipocytes.

False

True or False. Holstein dairy cows have gotten larger through the years due to natural selection and adaptation to environments that are warmer than their native environment.

False

True or False: Chewing gum that contains either sucrose or high fructose corn syrup should not have any effect on the body's insulin response (assume the gum is not swallowed after chewing).

False

True or False: The brain's response to an increase in blood glucose would be to initiate increased secretion of insulin.

False

True or False. During protein synthesis, DNA is converted to mRNA, which is then converted to protein.

False.

True or False. Glucose can move by simple diffusion through a solution (such as the extracellular fluid) from an area where it is in low concentration to an area where it is in high concentration.

False.

True or False. Precursors for tyrosinase synthesis should be able to move through the cell membrane as long as they have a concentration gradient driving their movement such that more are on the outside than on the inside.

False.

What would most likely result in significant edema within a tissue?

High blood pressure that causes blood proteins to be forced through fenestrated capillaries and into the extracellular fluid of the tissue

A physiological response in which a variable (either controlled or regulated) is changed in the opposite direction from the condition which initiated the physiological response

Negative feedback

Water following sodium from the extracellular fluid into the lumen of the sweat gland tubule would be an example of ______.

Osmosis

Movement of sodium and water into the tubule from the extracellular fluid in the dermis occurs between cells. This route of movement of substances between cells rather than through them is called _______.

Pericellular

A physiological response that prevents further deviations in a regulated variable but doesn't directly correct the deviation

Permissive feedback

Which of the following is a way in which primary and secondary active transport may work together?

Primary active transport can be used to create a concentration gradient of sodium such that sodium and glucose can move into the cell together via symport active transport

The amount of molecules is the likely bind to a

Protein, want higher amount

Simple diffusion:

Requires a concentration gradient

Glucose moving from an area of high concentration surrounding a capillary vessel to an area of lower concentration near cells within the tissue is an example of:

Simple diffusion

Of the scenarios described in the previous two questions, which one could accomplish the desired pumping of potassium ions the most quickly?

The cell with 250 sodium/potassium pumps in its membrane

Requires specific binding to molecule Changes conformation

Transportor

True or False. Edema often results in a tissue at times when high blood pressure causes proteins to be forced out of fenestrated capillaries and into the tissue.

True

True or False. The primary purpose of SGLT-1 in enterocytes is to create a concentration gradient of glucose such that more glucose is in the intracellular fluid as compared to the extracellular fluid on the basal side of the cell.

True

True or False: Foods that contain greater amounts of fructose may cause a greater dopamine release.

True

True or False: The glucagon response to blood glucose would be an example of negative feedback.

True

True or False. The symporter that is driven by sodium ions to bring glucose into a cell against its concentration gradient would be an example of a transporter rather than a channel.

True.

What should be able to move out of a cell that contains no membrane proteins as long as there is a concentration gradient such that there are more molecules on the inside than the outside:

Vitamin D, Cholesterol, Estrogen

A physiological condition that can be increased or decreased for a period of time in order to regulate variables that must be maintained within a narrow physiological range

controlled variable

During increased heat stress more sweat may be put on the ________ of the skin by _______ glands in order to increase cooling by _______. The result of this process should allow for increased heat transfer by _______ from the dermis to the epidermis, such that more heat is taken out of the blood as it passes through the _____ layer of the skin and therefore ______ of the body temperature is more easily maintained.

epidermis, ecrine, evaporation, conduction, dermal, homeostasis

Homeoinflammatory means

equally inflammatory

Movement of chloride out of the secretory cells and into the lumen of the trouble would be called

facilitated diffusion

An important substance or condition that must be maintained within its normal physiological range or else loss of function or even death could result. Z

regulated variable

The overall movement of ions would be

symport secondary active transport