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What can occur if you place a mildly hypothermic individual, who is shivering under heat lamps?
- The cutaneous thermoreceptors would detect increased temperature of the skin. In response, the receptors would send information to the hypothalamus stating that the person is now "warm enough"
- The individual would stop shivering and their core temperature would continue to decline making the hypothermia worse
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What happens when you immerse your hand into warm water? cold water?
- Increase temp change
- Increase Change in PPG amplitude
Decrease for both in cold water
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Where are the thermoreceptors of the thermoregulatory homeostatic mechanism located?
- Skin (peripheral)
- Hypothalamus (central)
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How does redirecting blood flow influence body temperature?
Tells the body to induce a homeostatic response
Vasoconstrict if cold and vasodilate if warm
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Under what conditions would more blood be directed to the skin?
Heat exhaustion, fever, hot environment
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Under what conditions would less blood be directed to the skin?
Cold environments, hypothermia
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Why is it important to not just warm the skin when experiencing hypothermia?
It will convince the body that it has completely re warmed when the core temperature hasn't risen
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What are some symptom of heat exhaustion? mild hypothermia?
Exhaustion: elevated temperature, flushed skin, sweat, dizziness, nausea, <104 degrees
Hypothermia: shivering, blue tones, confusion, apathy
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What do the chemoreceptors in the blood measure?
- Plasma oxygen
- Carbon dioxide
- pH levels
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What happens if the chemoreceptors detect low plasma oxygen levels?
Ventilation is increased in order to increase the blood's oxygen saturation
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What happens when CO2 enters the blood?
- Decrease in blood pH which suggests an increased cellular metabolism
- Respiration is increased in order to provide additional oxygen to compensate
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Blood pH
- Cells are extremely sensitive to blood pH levels so they must be kept in a narrow range
- The chemoreceptors can then react quickly to adjust ventilation as needed
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Respiratory alkalosis
Pathological increase in ventilation causes more carbon dioxide than usual to be removed from the blood resulting in an increase in pH
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Respiratory acidosis
A pathological decrease in ventilation causes an excess of carbon dioxide to be retained resulting in a decrease in pH
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Metabolic alkalosis
- pH increases because of a metabolic abnormality
- Respiratory rate decreases (increasing blood carbon dioxide levels( in an attempt to correct the pH imbalance
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Metabolic acidosis
- pH decreases because of a metabolic abnormality
- There is a normal carbon dioxide level with a low pH
- Respiratory rate increases in an attempt to decrease CO2
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CO2 equation
CO2 + H2O <-> H2CO3 <-> H+ + HCO3-
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Cause and effect for metabolic acidosis
Low pH -> high resp -> low CO2
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Cause and effect of metabolic alkalosis
High pH -> low resp -> high CO2
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Cause and effect respiratory acidosis
Low respiratory -> high CO2 -> low pH
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Cause and effect respiratory alkalosis
High resp -> low CO2 -> high pH
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Examine the pH and CO2 values at the end of metabolic acidosis. Could the observed carbon dioxide level have induced the pH change that occurred in this experiment?
No; disturbance was metabolic which why the pH was low as well as the CO2
pH induced CO2 levels
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What is providing the "compensation" in metabolic acidosis?
Increased respiratory rate- respiratory chemoreceptors sensed low pH & responded w/increased ventilation
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Why is the pH change different in metabolic acidosis, compensated and uncompensated?
Uncompensated means that ventilation is fixed and the pH problem becomes worse
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Could the carbon dioxide change observed in metabolic alkalosis have induced the observed pH change?
No because an increase in CO2 would produce a decrease in pH not a high pH
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Could the carbon dioxide change observed in respiratory acidosis have induced the observed pH change?
yes because increased CO2 leads to decrease in pH since CO2 is converted into carbonic acid which breaks into H+ and bicarb
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Could the carbon dioxide change observed in respiratory alkalosis have induced the observed pH change?
Yes because removing extra CO2 from the blood increases pH
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**What pH, CO2, and respiratory rate changes would be expected after an infusion of an acid?
Increase in H+ = decrease in pH = increase in respiratory rate = decrease CO2
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Barbiturate abuse can suppress respiration. How would this affect blood pH and carbon dioxide levels?
Low respiratory rate = increase CO2 = decrease pH
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What does the renal system regulate?
BP, plasma osmolarity, plasma sodium, plasma potassium, total body water, plasma ph, and others
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Renin
- An enzyme produced by the kidneys which leads to the production of the hormone angiotensin II
- Secreted in response to diminished BP at the kidney or diminished osmolarity
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Angiotensin II
- Leads to the production of the hormone aldosterone
- Produced when renin is present
- Constricts blood vessels, increasing resistance and BP
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What does renin secretion lead to
Increases in BP and/or blood sodium levels (increasing blood sodium increases plasma osmolarity)
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Aldosterone
- Secreted in response to angiotensin II
- Acts on kidneys where it causes the reabsorption of sodium by active transport
Causes the reabsorption of sodium and causes the excretion of potassium through the active transport pumps
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What happens when aldosterone secretion is increased? decreased?
- Increased: body will tend to retain sodium while losing potassium in the urine
- Decreased: body will tend to retain potassium while losing more sodium in the urine than usual
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Antidiuretic hormone (ADH)
- Secreted in response to increased plasma osmolarity or decreased BP (osmolarity of has the greater effect)
- Acts on the collecting duct allows water to be reabsorbed by osmosis
- Increases thirst, influencing water intake
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What happens when ADH secretion increases? decreases?
- Increased: body retains more water
- Decreased: body loses more water in the urine
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Osmolarity
- Function of the ratio of solute particles in a solution to the total volume of that solution
- Can be altered either by changing the number of solute particles present or the total volume present
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What does your body do when blood osmolarity is low?
- Try to increase the osmolarity by secreting more aldosterone and less ADH
- The increase in aldosterone increases sodium retention while the decrease in ADH leads to water loss in the urine; causing osmolarity to increase
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Body response to low BP
- Renal system will adjust in order to increase blood volume
- Increase in blood volume will tend to bring the BP back up
- Increasing both ADH and aldosterone secretion will maximize water retention at the kidneys
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If osmolarity is low
- Increase aldosterone
- Decrease ADH
- Increase osmolarity
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If osmolarity is high
- Decrease aldosterone
- Increase ADH
- Decrease osmolarity
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If BP is low
- Increase aldosterone
- Increase ADH
- Increase fluid retention (increase BP)
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If BP is high
- Decrease aldosterone
- Decrease ADH
- Decrease fluid retention (decrease BP)
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What happens in increased Na+ intake?
Plasma osmolarity
Renin
Aldosterone
ADH
Water intake
Urine Na+
Urine K+
Urine osmolarity
- Plasma osmolarity: increase
- Renin: decrease
- Aldosterone: decrease
- ADH: increase
- Water intake: increase
- Urine Na+: increase
- Urine K+: decrease
- Urine osmolarity: increase
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What happens in decreased Na+ intake?
Plasma osmolarity
Renin
Aldosterone
ADH
Water intake
Urine Na+
Urine K+
Urine osmolarity
- Plasma osmolarity: decrease
- Renin: increase
- Aldosterone: increase
- ADH: decrease
- Water intake: decrease
- Urine Na+: decrease
- Urine K+: increase
- Urine osmolarity: decrease
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What happens in decreased BP?
Renin
Aldosterone
ADH
- Renin: increase
- Aldosterone: increase
- ADH: increase
Work together for max results
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What happens in increased BP?
Renin
Aldosterone
ADH
- Renin: decrease
- Aldosterone: decrease
- ADH: decrease
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How will plasma osmolarity change if the kidneys retain more sodium (assume that body water and other electrolytes are unchanged)?
Increase plasma osmolarity
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How will plasma osmolarity change if the kidneys excrete more water (assume that other electrolytes are unchanged)?
Increase plasma osmolarity
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Assume that the kidneys begin to retain more water than usual, but less sodium (i.e water excretion is decreased, sodium excretion is increased). How will this affect plasma osmolarity? How could aldosterone and ADH secretion be manipulated in order to induce this kind of change?
- Decrease plasma osmolarity
- Increase ADH
- Decrease aldosterone
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How can aldosterone and ADH secretion be adjusted in order to maximize water retention?
- Increase ADH
- Increase aldosterone
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In addition to increasing aldosterone levels, how does the increase in renin that results during low BP help to increase the BP (consider the effects of angiotensin II)
If renin increase, it releases angiotensin II which causes vasoconstriction and increase resistance in blood vessels to raise BP
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Describe the hormonal response to an increased plasma osmolarity
- Increase ADH
- Decrease aldosterone
- Decrease renin
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How do the changes in aldosterone and ADH secretion to help correct the increase in osmolarity?
- Increase in ADH which will increase water retention
- Decrease in aldosterone which decreases Na+ retention which decreases the number of solutes and decreasing osmolarity
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Describe the hormonal responses to decrease in plasma osmolarity
- Increase in aldosterone
- Decrease in ADH
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How to the changes in aldosterone and ADH help correct the decrease in plasma osmolarity?
- Decrease ADH promote H2O loss
- Increase aldosterone which promotes Na+ retention which increase H+ of solutes to solution which increases osmolarity
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How do the changes in aldosterone and ADH that occur during low BP affect water reabsorption at the kidneys?
- An increase in aldosterone and ADH maximize H2O retention
- Aldosterone creates a large osmotic gradient while ADH allow H2O to flow the gradient freely
- Water follows salt to increase blood volume
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Explain the low urine potassium levels that developed during increased plasma osmolarity as a consequence of increased sodium intake, and the high urine potassium levels during decreased plasma osmolarity as a consequence of decreased sodium intake/
Increase Na+ intake decreased aldosterone secretion and aldosterone simulation increases the K+ excreted in the urine so the body retained more K+ bc the aldosterone decreased
Decrease in Na+ means increase in aldosterone secretion and increase in K+ to be excreted out in the urine; retain Na
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Nutrients
- Macromolecules that can only be absorbed when broken down into their monomer form
- Food digestion is a prerequisite to food absorption
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Enzymes
- Large protein molecules produced by body cells
- Biological catalysts that increase the rate of a chemical reaction without becoming part of the product
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Hydrolases
Digestive enzymes are hydrolytic enzymes which break down organic food molecules, or substrates, by adding water to the molecular bonds, thus cleaving the bonds between subunits or monomers
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Hydrolytic environment
- Its highly specific in its action
- Each enzyme hydrolyzes one, or at most, a small group of substrate molecule and specific environmental conditions are necessary for an enzyme to function optimally
For example: in extreme environments such as high temperature, an enzyme can unravel or denature due to the effect that temperature has on the 3-D structure of the protein
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Fiber
Cellulose which is a carbohydrate that cannot be hydrolyzed by the enzymes in our digestive tract because of the type of chemical bonds they contain
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Starch and sugar equation
- During digestion, starch decreases and sugar increases
- Starch + water --amylase--> X maltose
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Enzyme assay
- The chemical method of detecting the presence of digested substances
- IKI and Benedict's assay are two examples
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IKI assay
- Detects the presence of starch
- A normally caramel-colored solution changes black-blue in the presence of starch
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Benedict's assay
- Tests for the presence of reducing sugars, such as glucose or maltose, which are the digestion products of starch
- Reagent is a bright blue solution that changes to green to orange to reddish-brown with increasing amounts of maltose
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Salivary glands in digestion
Secretion of lubricating fluid containing enzymes that break down carbohydrates
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Oral cavity, teeth, tongue in digestion
Mechanical processing, moistening, mixing with salivary secretion
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Esophagus in digestion
Transport of materials to the stomach
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Liver in digestion
Secretion of bile (important for lipid digestion) storage of nutrients, many other vital functions
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Gallbladder in digestion
Storage and concentration of bile
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Small intestine
Enzymatic digestion and absorption of water, organic substrates, vitamins, and ions
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Pharynx in digestion
Pharyngeal muscles propel materials into the esophagus
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Stomach in digestion
Chemical breakdown of protein via acid and enzymes; mechanical processing through muscular contractions
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Pancreas in digestion
- Exocrine cells secrete buffers and digestive enzymes
- Endocrine cells secrete hormones
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Large intestine in digestion
Dehydration and compaction of indigestible materials in preparation for elimination
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What are the test results for amylase, starch, and pH 7 buffer that was first boiled and then incubated at 37 degrees?
- IKI test: +
- Benedict's test: -
Boiling denatures the enzyme so starch is never converted to sugar
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What are the test results for amylase, starch, and pH 7 buffer that was incubated at 37 degrees?
- IKI test: -
- Benedict's test: ++
Ideal conditions so there was sugar production for orange color in benedict
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What are the test results for amylase, D.I water, pH 7 buffer that is incubated at 37 degrees?
- IKI test: -
- Benedict's test: -
Control tube, no reaction bc there was no starch to react to
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What are the test results for D.I water, starch, pH 7 and incubated at 37 degrees?
- IKI test: +
- Benedict's test: -
Control tube, no enzyme but still starch
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Test results for D.I water, maltose, pH 7 and incubated at 37 degrees
- IKI test: -
- Benedict's test: ++
No starch but excess of maltose
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Test results for amylase, starch, pH 2 and incubated at 37 degrees
- IKI test: +
- Benedict's test: +
Some sugar produced because the enzyme can function but not effectively so there is leftover starch as well
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Test results for amylase, starch, pH 9 and incubated at 37 degrees
- IKI test: +
- Benedict's test: +
Some sugar produced because the enzyme can function but not effectively so there is leftover starch as well
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What pH buffer allowed the highest amylase activity?
7
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Which tube indicates that the amylase was not contaminated with maltose?
The tube with only amylase and no starch bc you shouldn't see any maltose
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Why are control tubes important
It shows if there was any contamination that may yield a false positive
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Would the amylase present in saliva be active in the stomach? Explain your answer
Maybe some activity because at a pH of 2 there was some sugar production
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What effect does boiling have on enzyme activity?
Inactivates and denatures the enzyme
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Test results for amylase, cellulose, pH 7
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Test results with peptidase, starch, and pH 7
Wrong enzyme so the starch can't be digested
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Test results for bacteria, cellulose, pH 7
Bacteria can take digest cellulose into sugar
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What is the effect of freezing a tube?
no effect
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How does the effect of freezing differ from the effect of boiling?
Freezing has no effect where boiling inactivates the enzyme
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Does amylase use cellulose as a substrate?
No it cannot break it down into sugar
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What effect did the addition of bacteria have on the digestion of cellulose?
Bacteria contains the enzyme cellulase because digestion of cellulose causes the IKI test to be negative and hydrolysis to happen
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What was the effect of the different enzyme, peptidase?
Peptidase's substrate is not a starch. It breaks down peptides while starch is broken down by amylase
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Pepsin
- Protein digesting enzyme
- Hydrolyzes proteins to small fragments
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BAPNA
- Synthetic "protein" that is transparent and colorless when in solution
- If active, the solution will become yellow
-
Which pH provided the highest pepsin activity?
2 which correlates with pepsin's location in the stomach
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Would pepsin be active in the mouth? Explain your answer
Works a little which was shown at the ph of 7 (mouth pH)
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Fat digestion occurs in two steps
- First: fats/oils -> bile; emulsification -> breaks down into droplets
- Second: fat/oil droplets -> lipase -> monoglycerides
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How to tell if digestion of fat is complete
Some of the end products of fat digestion (fatty acids) are organic acids that decrease the pH
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Can you tell if fat hydrolysis has occurred in a pH of 2
No bc it is already so acidic so you can't get much more acidic to see the change in pH
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Which pH resulted in maximum lipase activity?
7
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In theory, would lipase be active in the mouth? Would it be active in the stomach? Explain your answer.
- Yes in the mouth bc the pH is more condusive
- No in the stomach bc pH too low
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What is the substrate and what subunit is formed in the lipase experiment?
Vegetable oil and fatty acids
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Salivary Amylase
Organ of production
Site of action
Substrate
Optimal pH
- Salivary glands
- Mouth
- Starch
- 7
-
Pepsin
Organ of production
Site of action
Substrate
Optimal pH
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Pancreatic Lipase
Organ of production
Site of action
Substrate
Optimal pH
- Pancreas
- Small intestine
- Lipids/fats
- 7
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Based upon the results of your experiment, what is the optimal temp for digestion?
37 degrees C which is normal body temperature
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