Environmental Physiology

How does the physiology of high altitude‐adapted human populations differ from high altitude‐acclimatized humans such as mountain climbers?

***refer to notes***

What animals experience the types of dormancy?

animals that undergo hibernation, such as, bats, ground squirrels, rodents and marsupials.

What are examples of high-altitude animals?

birds and camelids species

What are the adaptive strategies that animals use to deal with hypoxia, and specifically physiology and biochemistry underlying respiratory physiology:

• Oxygen transport proteins • Tense vs. relaxed states of hemoglobin (Hb) • Oxygen equilibrium curves and P50 values

In order for fish to be able to successfully transition onto land, what were some of the constraints that they had to over come when they switched from having gills for gas exchange? How did they successfully overcome these constraints?

Nitrogen Waste Excretion: -must switch to a less toxic form of N waste (Least Toxic: Urea) -now that they are on land, they have to worry about not having enough water Desiccation: -Internalize gas exchange organs to keep them moist (humans) -development of ability to secrete fluids onto select mucous membrane (eyes) -reduce fluid loss via kidney -air breathers develop a thick impermeable skin

What are the osmoregulatory problems encountered by a freshwater teleost? Why do these problems exist?

- Hypertonic: higher [solutes] inside body relative to environment - Gain water - Passive salt loss

How do these freshwater teleost solve problems?

- Large amounts of urine loss - Active uptake of salt

How do changes in barometric pressure result in changes in the partial pressure of oxygen (PO2) at high altitude?

- at high altitude, a decrease in barometric pressure with an increase in altitude, leads to a decrease in PO2

What aspects of osmoregulatory constraints exist for air breathing animals that live in a freshwater habitat and how do they overcome these constraints?

-Freshwater has osmolarity of about 20 -Freshwater goes in through gills, very low in osmolarity, is diffusing into their blood, passively loosing salt -They actively take up salt through chlorine cells

How does the control of ventilation differ between aquatic (water‐breathing) and terrestrial (air‐breathing) animals? What is the reason for the difference in the primary gas that they "sense" to control ventilation?

-In fish, ventilation is primarily controlled by oxygen -in air breathing vertebrates, ventilation controlled by CO2 *other inputs possible (e.g. pH, motor stimulation)

How might you understand categories of desert animals and give examples

-Large Mammals; camel, oryx, elephant *difficulties loosing excess heat through their surfaces *tend to be pretty inactive during the day (docile, less mobile) -to avoid over loading their metabolism -if they loose too much heat they can suffer from desiccation

What aspects of osmoregulatory constraints exist for air breathing animals that live in marine environments and how to they overcome these constraints?

-Salt water has osmolarity of about 1000 -they have to drink water to maintain lower osmolarity in relationship to environment

Cross-Current

-bird lungs -lungs are between a series of air sacs that act as bellows *one will fill up, while the other one is releasing air *posterior and anterior air sacs -gas exchange occurs as air flows through parabronchi in lungs *air flow through is unidirectional *blood flow is crosscurrent -flow through and perpendicular blood flow to air flow -fairly efficient form of gas exchange at one end and inefficient at the other *partially because the media is going in one direction and blood is the only thing that crosses the media -arterial PO2 reaches a higher level than the PO2 of expired air

Why is air a better respiratory medium than water? How do these differences impact the types of gas exchange available to aquatic and terrestrial vertebrates?

-air has 30X more oxygen than water -air is less dense, less viscous -"better" respiratory medium than water -air is much easier to move/transport

How can an animal change the diffusion of water and/or air across a membrane. (Fick's Law)

-altering area and distance -altering temperature and concentration gradient

Where does the majority of ATP storage occur?

-as mammals 85% of ATP is in lipids -smaller portion in proteins -very few in carbohydrates

What additional physiological traits aid in birds flying at high altitude?

-crosscurrent: *unidirectional gas exchange *efficient form of gas exchange -lightweight body *air pockets within bone structure -more capillaries in their muscles -diameter of muscle fibers tend to be less *high altitude birds=increase in affinity oxygen for hemoglobin

How do these marine/seawater teleost solve problems?

-drink lots of water -actively secrete salt

Countercurrent

-fish gills -most efficient form of gas exchange -arterial PO2 reaches a higher level than the expired air -gradient is maintained over a wide range of PO2

What are the osmoregulatory problems encountered by a marine/seawater teleost? Why do these problems exist?

-hypotonic: lower [solutes] inside body relative to environment -water loss -passive salt uptake

Why are oxygen transport proteins important?

-increases the oxygen carrying capacity by 50 fold -partially changes the valency of metals and causes it to change colors

What does dormancy mean and how is energy budgeted during these processes?

-involves inactive sleep -lowering the metabolism; animals have less food requirement •Allows for more efficient energy storage -less energy is going to reproduction and growth -amount of maintenance is significantly reduced; only enough maintenance to keep body alive; vital signs, blood flow

How do water and air differ in their properties?

-less dense, less viscous -air 30X more dense than water -air is easier to move, transfer

How specifically are goldfish able to maintain high levels of anaerobic glycolysis but not accumulate high levels of lactate?

-lots of stored glycogen *goes into anaerobic metabolism/glycolysis -decrease in energy consuming processes -lactate circulates through muscles and is converted to ethanol -ethanol diffuses through gills before it becomes too toxic

How do High‐altitude animals like birds and camelid species have more evolved hemoglobins with higher O2‐binding affinity than their lowland relatives?

-lower P50 than other mammals -higher affinity for oxygen -shift equilibrium to the left -this has to do with their modified amino acid substitution camels -a 10mmHG drop in PO2 has a small effect on arterial O2 saturation - (100% > ~ 93%) -camels and goose had a common ancestor -relatively high P50; slight modification in amino acid

Pool -> Tidal Ventilation

-mammalian lung -inefficient form of gas exchange -mostly due to the fact that it is unidirectional (inhalants and our blood are flowing in the same direction), and expired fluid cannot have lower PO2 than the arterial PO2

How do diving animals maximize oxygen storage?

-move oxygen away from the lungs and towards the blood and muscle - when the dive initiates the lungs collapse and delivers oxygen to spleen and muscles

how do air breathers in marine environments maintain water loss?

-orbit of the eye in birds, nose or eyes of lizards and tongue of salt water crocodiles -secretions hyperosmotic to plasma and seawater *salt that they are secreting has more salt than their blood and seawater -Active transport of NaCl

Why can only very small animals rely on diffusion as their primary means of gas exchange? How does surface area/volume ratios play a role?

-really small animals can have shorter path length so they can use diffusion efficiently -larger animals must transport oxygen by bulk flow because they have a lower SA/V ratio

Why is evaporative water loss higher in small terrestrial animals than larger ones? Understand the graph.

-smaller animals have higher surface area to volume ratio which provides proportionally more surface area for cutaneous water loss -high mass specific metabolism causes proportionally more respiratory water loss

What are the strategies used by terrestrial frogs that live in hot dry areas to conserve water?

-some adults can burrow in sand, rocks, or mud -some emerge after rainstorms -some breed in ephemeral pools (very rapid development) -some have waxy skin; Waxy Monkey Frog -many use bladder as canteen (can store 20-50% of body mass as water

What facilitates successful cutaneous gas exchange?

-use their skin, must be wet to minimize distance of gas transfer -must have large membrane relative to the total volume of the animal -must have minimal distance to gas transfer -must have constant movement -obviously, this is not a great system for larger animals but it is a passive system and therefore very energy efficient -used primarily by small animals with high SA/V ratios

Open -> Cocurrent/Concurrent

-using cutaneous gas exchange, happens most often with amphibians (they have the most effective way of using cutaneous exchange) -a problem with this type of system is that expired PO2 is higher than arterial PO2 -"gap" between expired air and arterial blood determined by the included boundary layer (thicker the cuticle, the less gas exchange)

Why/when does the oxygen equilibrium curves and P50 values plateau?

-when it hits top plateau, it means carrying capacity in blood

What strategies to diving animals use to minimize the depletion of available O2 stores when they are diving?

...

What are the different respiratory strategies and which organisms are better suited for each type?

1.) Circulating the external media through the body -sponges, cnidarians, and insects 2.) Diffusion of gasses across the body surface is accompanied by circulatory transport -cutaneous respiration -skin must be thin and moist -most aquatic invertebrates, some amphibians, eggs of birds -open circulatory 3.) Diffusion of gas across the respiratory surface accompanied by circulatory transport -gills or lungs -vertebrates -closed circulatory

explain the different types of solutes that affect secretion of wastes

1.) Perturbing solutes: disrupt macromolecule function at normal concentrations found within an animal -inorganic ions found in body fluids (Na+, K+, Cl-, and SO4+), organic solutes, such as charges amino acids (arginine and lysine) -disrupting normal function (red line on graph) 2.) Compatible Solutes: have little effect on macromolecule function and can accumulate high concentration without deleterious effect/ being detrimental to cell -no matter if the concentration increases, the Km has the same value (blue line on graph) -polyols (trehalose, glycerol, and glucose), uncharged amino acids, including several of the alpha amino acids (alanine, glycine, serine, and proline) 3.) Counteracting solute: are deleterious when used alone or on its own, but in combination with others there is no deleterious effect -urea disrupts hydrophobic interactions and methylamines (TMAO) strengthen hydrophobic interactions

What are the six aspects of the diving response?

1.)extra oxygen storage -myoglobin and hemoglobin based -usually when the blood volume may increase in divers (birds and mammals) and increase in hemoglobin concentration -does not happen in reptiles 2.)apnia -suppression of breathing -suppress respiratory muscles 3.)hypo-perfusion -reducing blood flow to all of visceral organs except brain 4.)reducing metabolic rate -because organs are starved of oxygen, they can actually go into anaerobic metabolism but not for very long -they have lactate washout; anaerobic metabolism tends to increase release of lactate into the blood -happens when they are ascending, coming up from their dive 5.)lactate concentration -still not terribly high, because they suppress breathing and reduce metabolic rate it is very minimal 6.)bradycardia -lowering heart rate and cardiac output

What is the difference between conformers and regulators?

1.Conformers (Ectotherm; cold blooded) -allow internal conditions to change when faced with variations in external conditions -do not regulate homeostasis -thermoconformers 2.Regulators (Endotherm; warm blooded) -keep internal environment within narrow limits -able to maintain relatively constant internal conditions regardless of environment -oxyregulators -thermoregulators

What particular environments or physiological cases can we find hypoxia?

Aquatic Hypoxia: •environments are low mixing associated usually with high temperatures •higher density of organisms; more animals means that more oxygen is being consumed, which depletes O2 •high amounts of plant consumption relative to production Terrestrial Hypoxia: •higher altitudes •when organisms burrow Low O2 partial pressure in blood: •consequence of having this is usually due to exercise •diving > inadequate ventilation (hypoventilation) •leads to reduced blood hemoglobin content (can cause anemia)

How do the three forms of nitrogenous waste excretion differ in terms of the amount of water needed for excretion, the metabolic cost of production and toxicity to the animal?

Ammonia: -Metabolic cost of production: none -Toxicity: very (affects metabolism and amino acid transport) -500 mL of water required for 1 g of nitrogen Urea: -Metabolic cost of production: more expensive than ammonia -Toxicity: moderately toxic -50 mls of water required per gram nitrogen - requires less amounts of water Uric Acid: -Metabolic cost of production: very metabolically expensive -Toxicity: low toxicity -1 mL of water required per gram nitrogen -Very low solubility in water

Why is glucose a better metabolic fuel than fatty acids under conditions of low oxygen?

Brain ATP production and metabolism remain intact during hypoxia (fueled exclusively by glucose)

Animals found in different environments might select for a particular form of nitrogenous waste. Why?

Because each have different properties and conditions that best fit different animals in different environments.

How do humans differ from other diving mammals when they dive?

Humans do not collapse their lungs during a dive.

define humidic and xeric animals and provide one example of each.

Humidic: -land animals that are restricted to humid, water rich environments -amphibiens, toads, frogs Xeric: -land animals capable of living in very dry, water poor environments -camel, rattlesnakes, certain tigers

How was an understanding of phylogeny important for determining which aspects of the diving response were key to being a "good" diver?

IDK

What physiological traits define a "good" diver?

IDK

What is the difference between an ionoconformer and an ionoregulator?

Ionoconformers: conform to the ionic concentration to their environment * animals that have the same ion concentrations of extracellular fluid as the outer environment (ex: jelly fish) Ionoregulators: maintain a constant ionic concentration in their environment. *animals whose extracellular fluids have different ionic composition from the environment

Define aerobic dive limit.

It is the maximum amount of time they are allowed to be using their aerobic metabolism and at which point are they switching to anaerobic

What are some of the similarities and differences between lungs in amphibians and other terrestrial vertebrates?

Lungs in amphibians can extract oxygen through their gills or wet/moist skin - they either don't have lungs or are being developed as they grow up. Lungs in Terrestrial Vertebrates (mammalian lungs) do not have gas exchange through their skin.

How do animals match energy supply (Fuel switching) and demand (Regulated metabolic depression/suppression) during short‐term or seasonal hypoxia exposure (e.g. goldfish) ?

MATCHING ENERGY SUPPLY: -change the hemoglobin by altering the binding of O2 -increasing hemoglobin concentration -change regulatory properties -Often times with the energy supply side, there is an up regulation on energy efficient ATP pathways -regulation on how efficient they are with their ATP use/reproduction can be done in SHORT TERM MODULATION: -humans (climbing up to mount everest) LONGER ACCLIMATION RESPONSE: -organisms that are more hypoxic tolerant ATP turnover of cells as a function of time exposed to anoxia or hypothermia -hypothermia means body looses too much heat -when body is going through heat loss, body cant replenish that so oxygen plays a role in replenishing heat METABOLIC SUPPRESSION: ensures the survival is enhanced in O2 limited or cold environments METABOLIC FAILURE: largely, aerobic cold-sensitive animals -Anytime there is a reduction in affinity, increases P50

Is the diving response of marine mammals similar to humans during breath‐hold dives?

NO! animals already have oxygen stored in their tissues, which allows them to exhale right before a dive to enable the collapsing of their lungs.

What is the difference between tense vs. relaxed states of hemoglobin (Hb) ?

Tense: unloading -deoxygenated -oxygen becomes more easily unloaded from the hemoglobin Relax: loaded -oxygenated -oxygen binds/loads to the hemoglobin

How might you categorize desert animals and their ability to tolerate or avoid desert climate?

ULTIMATE EVADERS: -"Water holding" desert frog -Estivation (dormancy) -water holding bladder -these frogs are dormid at certain parts of the year; when awake they come out and drink a lot of water before going back to being dormid EVAPORATORS: -steady rate of evaporation -Categories -Birds, rabbits, small antelope, foxes -"middle sized" -depended on water; to allow them to cool down by evaporation -really only live on the fringe of deserts and around oases -Water balance and thermal strategies -huddle together - demonstrate evaporation by lowering metabolic rate -hypothermia tolerant -produce hyperosmotic urine relative to blood and plasma; very concentrated ENDURERS: -have very low rate of evaporation

Hb-O2 Saturation Curve

What is the P50? -point at where hemoglobin is 50% saturation, which is equivalent to hemoglobin affinity -At high P50 you have low O2 affinity; this causes shift to to right *tends to be in active vertebrates (ducks) *affinity of oxygen for hemoglobin decreases and oxygen can be unloaded *deoxygenated; tense -lower P50, left shift *higher affinity of O2 for hemoglobin *hypoxic organisms tend to have low P50 *oxygenated; relaxed -P50 can be altered by: *modulators concentration (H+, DPG, IPP) *decreases O2 affinity for hemoglobin *temperature, ph > decrease *DPG: diphosphoglycerate -Sequence Variation (different Hbs) *affects Hb-O2 directly or modulator binding

Understanding the Oxygen Equilibrium curve

a left shift in the oxygen equilibrium curve (HbO2 saturation curve) facilitates loading of O2 at the lungs and a right shift of this curve favors off loading of O2 at the tissues.

Nitrogenous waste is excreted in three principle forms, which are?

ammonia, urea & uric acid

Provide one animal that predominantly relies on each form of nitrogenous waste excretion.

amonia = fish urea = most amphibians uric acid = birds, reptiles and xeric frogs.

How do high altitude adaptations in animals differ from high‐altitude adaptations in humans with respect to hemoglobin?

high and low altitude humans do not differ in Hb sequence -10 mmHg drop in PO2 on arterial O2 salt at sea level (10%) -no change at sea level -we do not shift -minimize hypoxia by facilitating oxygen transport to our body tissues.

Why don't diving animals get the bends?

it is because their lungs collapse under high pressure so the nitrogen can not be released into their blood stream

What are some strategies used by terrestrial animals to reduce cutaneous water loss?

nasal cavity and countercurrent exchange

What are some strategies used by animals to reduce respiratory water loss?

nasal countercurrent heat exchange because the air in the desert is cooler than the air inside endotherm lungs that have moisture. do not loose water, they exchange the hot and cold air when breathing so the cold air coming in can receive the moist from the hot air coming out.

What is the difference between Osmoconformers and Osmoregulators

osmoconformers: conform to osmolarity of environment osmoregulators: maintain a constant internal osmolarity