Final Exam Notes

Question 1

Physiology

Answer 1

the study of how organisms work (form and function)

Question 2

Design rules for plans and animals

Answer 2

they must obey physical and chemical laws including scaling and they are constrained by evolutionary history, wha can it do with what it already has

Question 3

Scaling

Answer 3

how do things change when things change in size, as a physiological characteristic

Question 4

Safety factor

Answer 4

we have two lungs when we really only need the one, and the pancreas is 80% larger than we need it to be function properly … bridges are stronger than they need to be as well

Question 5

First law of thermodynamics

Answer 5

energy cannot be created nor destroyed

Question 6

Second law of thermodynamics

Answer 6

entropy (disorder) always increases, it takes energy to remain organized (alive), plants must capture solar energy and animals must eat

Question 7

Input / Output Budget

Answer 7

plants and animals require to take in the nutrients and energy in order to function - used for maintenance, generating of external work, reproductive fitness and biosynthesis, using energy as efficiently as it can in order to maximize the output (animals are very inefficient, plants are very efficient biomechanical maniacs, but they do perform the same similar things)

Question 8

Temperature

Answer 8

a measure of the speed or intensity of random motion, animals must adapt to their environment and the temperature in which they live, temperature is the motion by the atoms in the object

Question 9

Temperature of a substance is proportional to …

Answer 9

the product of the mean square speed of the random molecular motions and the molecular mass

Question 10

Temperature vs. Heat

Answer 10

temperature is not heat, heat is energy, heat and temperature are related in that energy will influence movements of molecules

Question 11

Heat

Answer 11

amount of energy in the object

Question 12

Temperature determines …

Answer 12

the direction of heat transfer - warm to cold

Question 13

Animals and their environment temperature …

Answer 13

despite the type of animal, there is a constant relationship between the organism and its environment in regards to heat transfers - using convection, evaporation, conduction, radiation, etc … to change the animals temperature, uses its environment

Question 14

Plants and animals and their environment temperature …

Answer 14

receives radiation heat from the sun either direct or reflected through the clouds, radiation from plants and the sky, this enters the animal, and the animal itself produces heat of its environment

Question 15

Absolute Zero

Answer 15

when molecules stop moving - there is no energy

Question 16

15 degrees celcius

Answer 16

where development and growth can occur for many insects and plants

Question 17

50 to 70 degrees celcius

Answer 17

the machines that carry out metabolism often have denaturing of their proteins near 50 to 70 degrees

Question 18

37 degrees celcius

Answer 18

body temperature of most mammals

Question 19

endotherms

Answer 19

generate internal heat

Question 20

ectotherms

Answer 20

rely on external temperature to determine body temperature

Question 21

homeotherm

Answer 21

defend a constant body temperature

Question 22

poikilotherms

Answer 22

allow body temperature to vary

Question 23

heterotherms

Answer 23

have more than one temperature set point, or switch between homeothermy and poikilothermy

Question 24

regional endothermy / heterothermy

Answer 24

different body temperatures in different parts of the body

Question 25

ectotherms and poikilotherms

Answer 25

some amphibians and plants

Question 26

endotherms and poikilotherms

Answer 26

plants and insects

Question 27

ectotherms and homeotherms

Answer 27

lizards

Question 28

endotherms and homeotherms

Answer 28

mammals

Question 29

relationship between temperature and metabolism in an ectotherm

Answer 29

in humans, metabolic rate (oxygen consumption) is relatively constant because we have constant internal temperature, but ectotherms vary their rate depending on their environment, increasing body temperature, increases metabolic rate in an almost exponential relationship

Question 30

Q 10

Answer 30

the temperature coefficient is the ratio of the rate of a process at one temperature over the rate of the same process (reaction) at a temperature of 10 degrees lower, how much does the rate of a process change over the space of 10 degrees celsius

Question 31

What can offset the response of Q10

Answer 31

acclimation

Question 32

rate increase for many physical and chemical processes

Answer 32

about 1 increase of the rate

Question 33

rate increase for biological reactions

Answer 33

about 2-3 increase of the rate for biological reactions

Question 34

how do temperatures changes occur

Answer 34

temperature determines motion and therefore the rate at which molecules encounter one another, more interactions = more reactions, increasing temperature increases the chance for collisions - more interactions and thereby increasing the amount of interactions that occur, temperature also determines the conformation and efficiency of enzymes (Q10)

Question 35

How do enzymes work

Answer 35

enzymes have an induced fit - requires a specific orientation of the molecules, temperature can affect the rate at which the substrate and enzyme encounter on another, warms = more often = more reactions

Question 36

Temperature and enzyme effectiveness

Answer 36

the enzyme’s active site can change shape with temperature, changing in binding affinity for substrate (generally warmer = weaker)

Question 37

What’s the limit of temperature and the enzyme’s effectiveness

Answer 37

once a certain temperature is reached, the binding site of an enzyme begins to change and therefore the substrate is no longer in correct orientation to the enzyme - there is a limit! at too high of a temperature, the enzyme will become denatured and cannot function at all

Question 38

Relationship between Km and affinity of an enzyme

Answer 38

Km = the amount of substrate required to reach half of the maximum rate of reaction (Vmax), the higher the Km means lower affinity - needs a lot of substrate to reach half of the Vmax, they are opposite of one another (Km and affinity), low Km = high affinity

Question 39

Enzyme affinity and temperature in the Goby fish

Answer 39

decreasing affinity as the temperature increases, what temperature is optimal? - normally around 30 degrees, the highest temperature is not optimal because it is too efficient because it actually ends up letting go of the substrate (poor catalytically) too easily

Question 40

Affinity is too high at lower temperatures, therefore …

Answer 40

the enzyme binds too tightly to the substrate making the reaction slower (not released as fast)

Question 41

Affinity is too low at higher temperatures, therefore …

Answer 41

the enzyme binds too loosely to the substrate making the reaction less likely to occur

Question 42

Protein’s structure at different temperatures

Answer 42

at higher temperatures it is not as tight as it adopts different conformations and lower temperatures it becomes even more unassembled

Question 43

Enzyme Adaptation

Answer 43

the same enzyme in different organisms, in different environments have all adapted to function in different temperatures depending on their environment, through adaptation these species have optimized the enzyme function for the environment in which they live

Question 44

Metabolic Rate

Answer 44

an animal’s rate of energy consumption, the rate at which it converts chemical bond energy to heat and external work, this rate is temperature dependent

Question 45

Fickle cue

Answer 45

it is not reliable - there are different seasons with different temperatures, not a good environmental cue to tell animals of what to do, plants and animals often use more reliable cues, like photoperiod to govern their seasonality

Question 46

Thermal inertia

Answer 46

the degree of slowness with which the temperature of a body approaches that of its surroundings and which is dependent upon its absorptivity, its specific heat, its thermal conductivity, its dimensions and other factors

Question 47

Thermal inertia and size

Answer 47

size does matter - a smaller organism will be more affected in a short term temperature change because a larger organism has more body mass meaning there is more area for heat to be stored

Question 48

What can an endotherm do physiologically with temperature changes

Answer 48

altering oxygen demand and delivery, change metabolism, change insolation (grow fur), membrane fluidity (more solid composition at low temperatures and more fluid at high temperatures) and enzyme denaturation (chaperon / heat shock proteins, change the enzyme at the amino acid level in order for them to function more effectively at different temperatures)

Question 49

Adaptation

Answer 49

genetically controlled trait that though the process of natural selection, confers an advantage to the individual, altered genome

Question 50

Acclimation

Answer 50

a chronic response of an individual to a changed environment in numerous ways (ex. summer vs. winter), it is an altered genome expression, altered phenotype, using what you already have and changing it for the environment

Question 51

Enzymes between closely-related species

Answer 51

enzymes have adapted over time to have different optimal temperatures, even though the different species are closely-relted of the same genus, genome isn’t changing but there are different parts expressed or some portions more frequently expressed

Question 52

Thermoregulation

Answer 52

maintaining constant body temperatures regardless of the environment

Question 53

Environment of the forest vs. dessert landscapes

Answer 53

going with the flow of the environment is easier in some places than others, it would be easier in the watered environment of the forrest rather than the sun rich environment

Question 54

Are ectotherms completely at mercy of their environment?

Answer 54

NO - the sum of all heat inputs and outputs should be zero, including radiation, convection, conductance, latent heat exchange (transpiration / evaporation) and metabolism

Question 55

Radiation in plants

Answer 55

they can minimize radiation in the heat absorbed or lost by changing leaf colour (red or white in sunny and green in shaded area) or their leaf angle

Question 56

Convection in plants

Answer 56

changing leaf shape (how much of the leaf is exposed to the sunlight), more pointy leafs in the sun environment, more rounded within the shade, heat exchange with air molecules

Question 57

Behavioural thermoregulation in plants

Answer 57

rolling leaves and pointing them vertically reduces sun interception, saving water, maximize sun exposure and minimizing water loss

Question 58

Behavioural thermoregulation in lizards

Answer 58

lizards move around the island to their optimal temperature, they are not evenly distributed - movement is a behavioural change

Question 59

Lat heat of vaporization of water

Answer 59

2270 kJ / kg

Question 60

If you are hot and have a glass of cold water

Answer 60

it is more effective to dump it on your head than it is to drink it in order to cool off faster and more efficiently

Question 61

If you are already sweating and have a glass of cold water

Answer 61

it is better to drink it because your body is already maximally evaporating

Question 62

Impact of CO2 levels on leaf temperature

Answer 62

in areas of higher CO2 levels - the leaves do not transpire as much because they already have enough CO2 for survival, therefore their stomates are closed and evaporation is no longer performed, therefore they have higher leaf temperature

Question 63

Where does ectotherm heat come from?

Answer 63

metabolism, futile cycling / alternative oxidase pathway (in plants) and muscle contractions (in animals)

Question 64

Alternative oxidase pathway in plants

Answer 64

the product is mostly water, there is no proton pumping, therefore no energy (ATP) is formed

Question 65

Use of metabolic heat in plants

Answer 65

to warm up tissues to a more optimal physiological temperature, to attract pollinators in early spring - increases odour diffusion and provide warmth for ectothermic pollinators, less energy that the pollinators have to use if the plant itself is warmer

Question 66

Heat generation for insects when they are in flight

Answer 66

greater heat production as the air temperature is cold, less energy has to be expended when the air temperature is warmer

Question 67

During brooding young for the queen bee

Answer 67

it will increase its metabolism in order to produce more heat when the air temperature is lower

Question 68

bees defending the nest

Answer 68

bees will come together forming heat together to kill enemy

Question 69

why are fish ectotherms

Answer 69

fish can generate heat (like anything else with metabolism), but they have problems keeping it because they are surrounded by thermally-conductive water, they are in a medium that exchanges energy so quickly, too thermally conductive, that the fish cannot maintain a higher body temperature

Question 70

Why are ectotherms ectotherms when they generate internal heat?

Answer 70

ectotherms don’t generate heat that contributes to interna function, but all organisms generate some heat through metabolism

Question 71

Rete mirabile

Answer 71

warm arterial blood looses heat to the cooler venous blood which goes back to the heart / core, allows for very effective counter-current exchange of heat

Question 72

Red muscle

Answer 72

high myelin - very metabolically active, therefore their temperature is elevated above water temperature, they have more continuous activity, heat comes from the normal heat produced by contractile activity of the red muscles, the only different is the heat is retained, red muscles undergo more quick, shorter bursts of activity

Question 73

Regional endothermy in some bony fish

Answer 73

allows long migration through water at different temperatures, to allow better performance as a predator chases the prey int colder water, and it improves in power output of muscles

Question 74

Overview of metabolism

Answer 74

metabolism is the breakdown of complex molecules into simple molecules, energy is required to break down the molecules

Question 75

Light dependent reaction of photosynthesis

Answer 75

uses water to produce oxygen, uses ADP, NADP and produces ATP and NADPH, energy input comes from photons to cause charge displacment, photochemistry takes place

Question 76

Light independent reaction of photosynthesis

Answer 76

uses carbon dioxide to produce sugars and uses ATP and NADPH to produce ADP and NADP, energy input from light dependent reactions

Question 77

Light = energy

Answer 77

shorter wave lengths have higher energy contents and this can actually be too damaging to photons, longer energy wave lengths have lower energy contents and is not sufficient enough for photochemistry

Question 78

Optimal wavelengths and energy for photosynthesis

Answer 78

visible spectrum around 450 or 500 because this is where chlorophyll a and b can efficiently absorb light to be transferred on to the photosystems (more than 600 nm nothing will happen)

Question 79

Pigments

Answer 79

are molecules that absorb photons, generally coloured in the wavelength they reflect

Question 80

Fluorescents

Answer 80

energy is lower because energy is lost

Question 81

chlorophyll a and b and beta carotene

Answer 81

absorbs higher energies than what is used during photosynthesis (than that absorbed by photosystem I and II)

Question 82

Where are photosystems I and II found

Answer 82

photosystem I is found in the stroma and photosystem II is found in the thylakoid membrane, linked through mobile electron carriers

Question 83

Behavioural adaptation of chloroplasts

Answer 83

deep light - the chloroplasts clumped together excuse they try to absorb as much light as possible and they become separated in a strong light

Question 84

How much energy actually needs to be present from photosynthesis

Answer 84

only about 10% of sunlight is actually needed for photosynthesis

Question 85

Energy transferring to the reaction centre

Answer 85

the reaction centre doesn’t absorb much energy itself, light absorption occurs in the antenna complex (can include chlorophyll a and b) that capture incoming light, they transfer energy towards the reaction centre (found within photosystem I and photosystem II)
it is movement of energy, not movement of electrons in this portion, energy from harvested photons is transferred to the reaction centre, electron movement takes place at the reaction centre
two photosystems required in oxygen involving organisms - mainly plants

Question 86

Photosynthetic photosystems

Answer 86

photosystem II receives the energy of the photon and water is oxidized to give the photosystem II an electron and protons remain in the lumen, the electron is taken by an electron mobile carrier (PQ) to cytochrome c where another proton is pumped into the lumen using some of the energy from that electron, then another electron mobile carrier (PC) takes the electron to photosystem I where the energy is used to reduce NADP to NADPH

Question 87

The milieu interieur

Answer 87

term to describe the internal environment of organisms as distinct from the external environment, internal conditions held constant despite changes on the outside in their environments (ex. blood glucose, temperature, pH)

Question 88

conformity

Answer 88

variations

Question 89

regulation

Answer 89

regulates no matter what the external environment conditions are

Question 90

mixed conformity and regulation

Answer 90

animals that do both, most animals have some factors they regulate closely but others they allow to conform

Question 91

advantage of regulator

Answer 91

not required to stay in a certain environment, can move more, they don’t have to constantly adapt to a changing environment

Question 92

disadvantage of regulator

Answer 92

requires a lot of energy, especially costly for temperature

Question 93

advantage of conformity

Answer 93

energy is much less

Question 94

disadvantage of conformity

Answer 94

body most have mechanisms to deal with the constant change of the environment

Question 95

zone of tolerance

Answer 95

sets limits of where the organism can live, due to limits of regulation, range of which an organism can regulate its internal conditions, at each extreme they must conform, if these zones are reached, their fitness decreases

Question 96

Homeostasis

Answer 96

the coordinated physiological processes which maintain most of the constant states in the organism, relatively stable internal physiological environment, usually involving extensive feedback mechanisms

Question 97

How does homeostasis work?

Answer 97

there is a controlled variable (ex. pH, temperature), and a sensor (hypothalamus) compares the value of this controlled variable to the set point (what it should be) and sends a signal to the effectors of the body to begin working on changing the value back to the set point

Question 98

Negative feedback loop

Answer 98

it shuts off once the set point is reached

Question 99

On / Off vs. proportional control negative loop

Answer 99

measures how far you are to the set point and gives a more strong or weak control depending on how off it is from the value

Question 100

Control in homeostasis

Answer 100

hormonal (ex. insulin and glucagon), neuronal (vasoconstriction), biochemical and molecular (ex. cytoplasm composition)

Question 101

Fever - homeostatic

Answer 101

when you have a fever, the set point is altered, it is still regulated but at a new set point, regulated very closely, little fluctuation when you have a fever in body temperature

Question 102

Positive feedback

Answer 102

control system reinforces deviation of a controlled variable from set point (ex. oxytocin in breast feeding), change promotes more change in the system

Question 103

Scaling definition

Answer 103

the study of structural, mechanical and physiological properties change with changing size, an organisms size affects its structures and mechanisms

Question 104

Sizing of an animal and its body mass

Answer 104

as linear size doubles, body mass increases 8 folds (2 to the power of 3), bones get bulkier and longer

Question 105

isometric scaling

Answer 105

things change by the same factors, direction proportionality, length is doubled therefore mass is doubled, linear relationship

Question 106

isometric scaling on a graph

Answer 106

slope is 1 and intercept is 0

Question 107

allometric scaling

Answer 107

proportionality changes with size, relationship is not 1:1 (allo means other), non-linear relationship

Question 108

allometric scaling on a graph

Answer 108

slope is more or less than 1, intercept may or may not be 0

Question 109

Using scaling to understand physiology

Answer 109

summarizing huge data sets, predicating unknowns, can look for deviations (residual analysis), there can be evolutionary signals in the similarities as well

Question 110

Heart rate vs. Heart weight

Answer 110

heart weight relative to body size remains the same, but heart rate changes dramatically for different organisms

Question 111

Catabolism

Answer 111

breakdown of molecules to release energy

Question 112

Anabolism

Answer 112

use of energy to assemble molecules

Question 113

isolated systems

Answer 113

will eventually decay to randomness (entropy increasing), no energy or matter is exchanged

Question 114

open systems

Answer 114

exchange heat with its surroundings, will not decay to disorder, will remain in organized state

Question 115

energy definitions

Answer 115

capacity to do mechanical work (force x distance) or capacity to increase order

Question 116

energy that can do physiological work

Answer 116

chemical, electrical, mechanical can do physiological work (to do physiological work in order to maintain organized state of the organism)

Question 117

what energy cannot do physiological work

Answer 117

heat

Question 118

chemical bond energy

Answer 118

the energy liberated or required when atoms are rearranged into new configurations, totipotent (can be harnessed and used for other mechanisms, it drives everything else)

Question 119

electrical energy

Answer 119

the energy that a system possesses by virtue of the separation of the positive and negative charges (potential), does physiological work as well (totipotent) (ex. membrane potentials used to pump other things across the membrane)

Question 120

Mechanical energy

Answer 120

the energy of organized matter in which many molecules move simultaneously in the same direction, totipotent / high grade (ex. moving a limb or circulating blood)

Question 121

High grade energy vs. low grade energy

Answer 121

high grade energy also known as totipotent can be used to perform physiological work while low grade work cannot, it is considered waste

Question 122

heat energy

Answer 122

the energy of random motion, all matter above absolute zero temperature possesses heat energy, it is low grade and considered a waste

Question 123

why is heat important if it is a low grade energy

Answer 123

heat is important because it determines temperature which influences physiological rates, but does not do direct physiological work

Question 124

calorie

Answer 124

amount of energy (heat) to raise the temperate of 1 gram of water by 1 degree

Question 125

power

Answer 125

rate of energy used per unit of time

Question 126

Input / Output budget, more detail

Answer 126

all absorbed chemical energy (energy that can be absorbed in the body) is either stored in chemical energy or eventually converted to heat, efficiency of ATP to mechanical work is about 25% (that actually moves you around, must is internal muscle movement, or heat production / loss)

Question 127

Biosynthesis in input budget

Answer 127

energy is kept within the body (growing or fat storage) or energy that exists the body (ex. skin lose, gametes)

Question 128

Efficiency of metabolism

Answer 128

very inefficient - about 75% of energy is lost by heat (rearranging molecules is expensive)

Question 129

Maintenance of the input budget

Answer 129

all of this energy eventually ends up at the heart (ex. body temperature, pumping blood)

Question 130

External work energy use in input budget

Answer 130

movement of stuff outside of body (ex. moving yourself or other things), friction that is created through movement produces heat

Question 131

measuring metabolic rate through direct calorimetry

Answer 131

metabolic rate is measured directly from the amount of heat released by an organism, melts ice surrounding it which is then measured

Question 132

measuring metabolic rate through indirect calorimetry

Answer 132

metabolic rate is calculated from the concentrations of oxygen consumption and carbon dioxide production or by material balance (energy in - energy out), indirect because you are measuring the products of metabolism

Question 133

Heat produced between different energy molecules from food sources

Answer 133

much more heat is produced when the animal is burning off lipids or proteins, but there is very little to no change of heat for carbohydrates being used in metabolism

Question 134

Basal metabolic rate

Answer 134

in endothermic homeotherms, done in fasting and resting conditions

Question 135

Standard metabolic rate

Answer 135

used for animals that do not alter their temperature (ectothermic poikilotherms), still in fasting and resting conditions at a defined temperature

Question 136

Fixed metabolic rate

Answer 136

daily energy expenditure of a free living animal

Question 137

Allometric scaling of metabolic rate

Answer 137

a larger animal eats a lot more food, but when the amount of food is scaled to the amount of energy it needs, a smaller animal eats much more than its body weight for the energy it needs, but a larger animal does not need as much energy from the food compared to its larger body weight

Question 138

weight-specific metabolic rates

Answer 138

when you get small, your metabolic rate gets much higher, this relationship may be due to smaller animals having a greater surface area for their mass therefore they will be losing heat at a greater rate (maintaining same body temperature requires higher metabolic rate to produce more heat)

Question 139

Costs of Activity

Answer 139

measuring the oxygen consumed and carbon dioxide produced during different locomotion activity

Question 140

Animals that swim and energy costs

Answer 140

the energy cost exponentially increases with speed

Question 141

runners and the energy costs

Answer 141

the energy cost linearly increases with speed

Question 142

smaller animal vs. larger animal and energy costs

Answer 142

smaller animals have a higher energy cost than a larger animal to go the same speed, takes a lot of energy for small animals to get somewhere in good speed

Question 143

Costs of activity in flying birds

Answer 143

when a bird flies faster they get lift, but they also have to overcome drag which means more energy is needed, when a bird flies slowly they are just hovering but they need to overcome the force of gravity - high energy, middle speeds requires less energy then higher or lower speeds

Question 144

The metabolic ceiling

Answer 144

metabolic rate that is the limit of the organism, metabolic machinery (ex. heart, liver) is what contributes to their metabolic limit

Question 145

how much energy should a parent animal give to their children

Answer 145

they found it was about 4 to 5 times their BMR

Question 146

Higher BMR requires …

Answer 146

a bigger heart, or more efficient liver to support this

Question 147

Aerobic activities and BMR

Answer 147

for activities like aerobic activities you can perform 6 to 8 times your BMR

Question 148

Multiples of your BMR sustained

Answer 148

this will only be sustained for a few minutes, multiples of your BMR can only be done for shorter timer periods (no longer than a few weeks), this requires continuous food and energy replacement through the time for the longer time periods, it takes larger, more expensive organs to support greater peak metabolic rates

Question 149

Endothermic homeotherms and their physiological features

Answer 149

maintain a high and stable body temperature using internal heat, high resting metabolic rate (cellular, tissue and whole animal levels), and insulation (fur, feathers, blubber) is usually present to retain heat

Question 150

Thermal neutral zone

Answer 150

range of temperatures where the metabolic rate does not change for an endotherm, getting below a certain point (the lower critical temperature) the metabolic rate must increase to increase body temperature and further mechanisms must kick in

Question 151

Vasoconstriction

Answer 151

when you are cold, your blood vessels can vasoconstrict in order to keep the blood further from the skin and keep heat in

Question 152

vasodilation

Answer 152

when you are too hot, your blood vessels dilate in order for the blood to get closer to your skin and the heat can be evaporated out through sweat glands and leave the body

Question 153

Mechanisms to change thermal conductance

Answer 153

thermal conductance is how easier it is for an organism to gain or lose heat, can change this through vasoconstriction, vasodilation, pilomotor response, ptilomotor response and posture changes

Question 154

pilomotor response

Answer 154

contraction of smooth muscles of the skin caused by cooling and resulting in goose bumps

Question 155

ptilomotor response

Answer 155

response of the smooth muscles of the skin during periods of excessive heat

Question 156

postural changes

Answer 156

a postural position more curled up in order to preserve body heat or huddling - huddling close with others of your species in order to warm yourself up

Question 157

Arteries and veins maximizing heat retention

Answer 157

if the artery is right next to the vein, the heat will move from the high temperature of the artery to the low temperature of the vein which keeps the heat within the core and keeps the paws (extremities) colder during cold temperatures

Question 158

Arteries and veins minimizing heat loss

Answer 158

if the artery and vein are further apart, heat will not be exchanged until the capillaries in the paws which results in warmer extremities and lower core body temperature

Question 159

Cold adapted animals and thermal conductance

Answer 159

cold adapted animals have a lower thermal conductance than tropical animals

Question 160

Reducing thermal conductance mechanisms

Answer 160

foxes have larger coats in the winter to reduce thermal conductance, have lower thermal conductance during the winter than in the summer

Question 161

Shivering

Answer 161

caused by non-synchronous muscle contractions and generates excess heat

Question 162

Shivering and hamsters

Answer 162

if they are acclimated to a higher temperature, their muscles will have very high electrical activity as they shiver to keep warm in low temperatures, but in hamsters when they are acclimated to a lower temperature, their muscles do no have to work as hard in shivering and therefore have much lower electrical activity during shivering at cold temperatures, but they still work harder than in warm temperatures

Question 163

Non-shivering thermogenesis

Answer 163

production of excess heat by ion leaks and uncoupling in the mitochondria in brown adipose tissue used for ATP synthesis which used for uncoupling of ions, no net ATP but it does produce a lot of wasted heat

Question 164

Brown adipose tissue

Answer 164

has a lot of mitochondria to produce this extra heat, it is specialized for non-shivering thermogenesis

Question 165

Upper critical conductance

Answer 165

at the UCT - conductance is maximal, above the UTC, excess heat can be stored allowing the animal’s temperature to drift up (which saves it a lot of water) or heat can be lost through evaporation, heat can also be lost through sweating, licking, panting and gular flutter

Question 166

Aerobic metabolism

Answer 166

is dependent on the exchange of oxygen and carbon dioxide from the environment

Question 167

Relying only on diffusion for gases

Answer 167

it is too slow to maintain the rates of gas exchange needed to support the metabolism of larger organisms, for very small organisms, diffusion would be affective because its size allows this movement - larger surface area relative to its mass / volume

Question 168

Gas exchange in respiration

Answer 168

getting oxygen out of the external medium and into the cells - often via the circulatory system and getting carbon dioxide out of the cells and into the external medium

Question 169

where is the oxygen

Answer 169

about 21% of the air in the atmosphere is oxygen, but very little dissolved in water, therefore water breather must process a lot of water in order to absorb the oxygen they need, air breathers have a larger concentration of oxygen available for breathing therefore less air processed

Question 170

Partial pressure

Answer 170

each gas in a mixture (either a gas or a solution) exerts their own pressure, partial pressure is the amount of pressure that the gas of interest exerts

Question 171

Partial pressures of gases in the atmosphere

Answer 171

21% of oxygen, 78% of nitrogen, 0.93% argon and 0.04% of carbon dioxide

Question 172

Difference in partial pressures and environments

Answer 172

partial pressure of air will be slightly lower in a lecture hall or crowded room because we are breathing oxygen in, going up in elevation air is thinner and therefore contains a lower oxygen concentration

Question 173

Gases dissolved in liquids

Answer 173

not the same as having air bubbles, partial pressure of a gas in a liquid is proportional to the partial pressure of that gas in the air

Question 174

Why wouldn’t a gas contribute to partial pressure in a solution?

Answer 174

gases that have reacted chemically do not contribute to partial pressure in solution because it is no longer the same chemical (that you were measuring the partial pressure of before), only free gas molecules contribute to the overall pressure of the mixture

Question 175

Henry’s Law

Answer 175

gas dissolved in solution, its concentration is a product of its partial pressure and its solubility in a liquid

Question 176

Gases solubility in water

Answer 176

oxygen has a very low solubility in water, while carbon dioxide is quite a bit higher

Question 177

Solute Diffusion - the Fick Equation

Answer 177

net movement of a molecule, moving mostly from high to low but some move from low to high concentration and therefore it must be termed as a net movement, rate of net movement of a molecule is influenced by the diffusion coefficient, the concentration gradient and the area availability of diffusion

Question 178

What factors influence the rate of diffusion of gas molecules?

Answer 178

the partial pressure gradient, surface area available for diffusion, diffusion coefficient, molecular mass (larger = slower diffusion), distance / width of the membrane (larger = slower diffusion)

Question 179

What factors of gas diffusion are constant?

Answer 179

molecular weight of the gas, diffusion coefficient and solubility of the gas

Question 180

What factors of gas diffusion can be changed?

Answer 180

area available for diffusion, partial pressure gradient and width of the membrane can all be altered

Question 181

What determines the diffusion of gases?

Answer 181

the partial pressure of a gas, not absolute concentration of the gases

Question 182

Convection vs. diffusion

Answer 182

convection can break dependence on diffusion, and enhance gas movement, diffusion has its limits, organisms have to rely on convection or bulk flow to move gases over larger distances

Question 183

Gas transport in animals

Answer 183

often is a combination of convection and diffusion

Question 184

tidal convection

Answer 184

in and out breathing, ventilates lungs

Question 185

Movement of gases in respiration

Answer 185

the partial pressure of oxygen is higher in the atmosphere than in our lungs, therefore it moves inwards during inhalation through convection and partial pressure of carbon dioxide is greater in the lungs than the atmosphere therefore causing carbon dioxide to exit during exhalation

Question 186

breathing out very deeply during exercise

Answer 186

when you breathe out very deeply during exercise you can lower the partial pressure even less in the lungs and therefore the partial pressure gradient between the lungs and the atmosphere is even greater and therefore more oxygen enters in the next inhalation

Question 187

diffusion of gases into the bloodstream

Answer 187

partial pressure is higher in the arteries / capillaries than it is in the tissues of the body, therefore oxygen diffuses to the tissues and is used in the body
constant new flood of blood from the heart with high partial pressures

Question 188

unidirectional flow (convection) in the circulatory system

Answer 188

larger distance than diffusion, partial pressure in the blood moving trough to extremities lowers as it is used up by the tissues

Question 189

diffusion from capillaries into tissues

Answer 189

substantial partial pressure drop as the oxygen is diffused from the capillaries to the tissues (mitochondria) where respiration actually occurs, fairly steady decrease of oxygen partial pressure throughout the circulatory system

Question 190

In the absence of active transport, the diffusion of solutes is driven by the chemical potential of the solute, by contrast, dissolved gases can diffuse against a concentration gradient, this is because …

Answer 190

differences in partial pressure govern gas diffusion

Question 191

impact of reduced partial pressure of oxygen - adaptation to elevation

Answer 191

two different elevations - higher up, the partial pressure is much less than at sea level
main difference of the population of people living at these two levels is their adaptation to the reduced partial pressure of oxygen primarily through large lung capacity
if the partial pressure gets too low, it can cause respiratory distress
regardless of the the partial pressure of oxygen in air coming in, the population of people have very similar partial pressures of their venous blood

Question 192

Animal gas exchange

Answer 192

external environment medium and internal body tissues separated by some gas-exchange membrane
getting rid of waste (carbon dioxide) the opposite way from the taking in of oxygen
only works if you have higher partial oxygen pressures on the outside and lower on the inside, and higher partial carbon dioxide pressure on the inside than on the outside
partial pressure of one gas to another does not matter, the movement of these gases only rely on the partial pressures of the same gas in opposite environments

Question 193

gas exchange membrane

Answer 193

a thin layer of tissue consisting typically of one or two simple epithelia which separates the internal tissues of the animal from the environmental medium (air or water)

Question 194

lungs

Answer 194

internal organs that contain the medium of the oxygen required, are invaginated

Question 195

external gills

Answer 195

project into external environmental medium (evaginated - external), surrounded by the medium

Question 196

internal gills

Answer 196

still considered evaginated because they are a continuation / external to the body cavity, evaginated from the body and project into a superficial body cavity through which the environmental medium is pumped

Question 197

Ventilation is active if ..

Answer 197

the animal creates the ventilatory currents of air or water that go down to and come from the gas exchange membrane, using forces of suction or positive pressures that it generates by use of metabolic energy

Question 198

Ventilation is passive if ..

Answer 198

environmental air or water currents directly or indirectly induce flow to and from the gas exchange membrane

Question 199

rate of O2 uptake (active ventilation) =

Answer 199

volume of the medium and difference between the concentration of inhaled and exhaled gas, rate because it is a continuous process (time factor), how much is taken up by the organism over net time

Question 200

O2 extraction efficiency

Answer 200

what proportion of the oxygen coming in compared to oxygen be removed

Question 201

Mammals efficiency of O2 extraction

Answer 201

27% efficiency

Question 202

Four anatomical variations of gas exchange

Answer 202

tidal gas exchange, cocurrent (concurrent) gas exchange, countercurrent gas exchange and cross-current gas exchange

Question 203

Tidal gas exchange

Answer 203

inhalation and exhalation of air - common mechanism for mammals
air in lung is able to exchange gas with the bloodstream, diffusional transportation requires close contact
partial pressure of oxygen in the blood cannot be greater than lung
short distances and close contact required
not as efficient as other cases

Question 204

Cocurrent (Concurrent) Gas exchange

Answer 204

whenever the medium is in close contact with the blood - moving in the same direction (diagram on the left)
how much time it has in contact between the blood and the medium dictates how much gases are exchanged
this can be maximized (the time of contact) to maximize oxygen absorption
diffusion of oxygen and carbon dioxide between medium and blood along contact axis
found in some gill
50-50 equilibration at best

Question 205

Countercurrent gas exchange

Answer 205

always higher partial pressure in the medium relative to the blood, always exchange to the blood stream
distance for medium to travel in the opposite direction of the blood will determine the efficiency of gas exchange
diagram on the right
diffusion of oxygen and carbon dioxide between medium and blood along contact axis
found in some gill types
much higher extraction efficiency

Question 206

Cross-current gas exchange

Answer 206

blood coming in always at very low partial pressure relative to the medium
blood system divided into many routes in order to maximize contact points and time for efficient exchange
found in bird lungs
diffusion of oxygen and carbon dioxide between medium and blood along contact axis
high extraction efficiency due to unidirectional medium flow

Question 207

Carbon dioxide arterial partial pressure in water breathers

Answer 207

the partial pressure of carbon dioxide in the blood leaving the breathing organs is always similar to the carbon dioxide partial pressure in the ambient water, regardless if tidal, co-current, counter-current or cross current

Question 208

Carbon dioxide arterial partial pressure in air breathers

Answer 208

the partial pressure of carbon dioxide in the blood leaving the breathing organs is usually far above the carbon dioxide partial pressure in the atmosphere because you need the partial pressure gradient in order for carbon dioxide to leave the lungs and exit the body

Question 209

Low oxygen - detection and response

Answer 209

whole body scale - increasing gill or lung ventilation (increasing rate of breathing = more oxygen)
intracellular, cell scale - hypoxia-inducible factors 1 and 2 (HIF-1 and HIF-2) increase in concentration in a cell when the cell experiences hypoxia to increase the secretion of erythropoietin which enhances production of red blood cells and therefore greater oxygen carrying capacity of the blood and promote angiogenesis - the development of new blood capillaries

Question 210

Gas exchange membrane area scales …

Answer 210

allometrically with body weight - almost linear, birds and mammals are higher (they have higher surface area for gas exchange), more than fish, amphibians and reptiles but this does not mean they have larger lungs

Question 211

Gas exchange membrane area between endothermic homeotherms vs. ectotherms

Answer 211

endothermic homeotherms have greater gas exchange membrane area than ectotherms of the same body mass

Question 212

Gas exchange membrane thickness

Answer 212

does not scale - no matter how large the animal is, the membrane thickness does not really change, mammals and birds have much thinner gas exchange membranes than most other organisms of the same body weight, reptiles have thickness similar to birds and mammals than fish

Question 213

How to breathe water

Answer 213

fast ventilation - more water across respiratory surface = more oxygen to absorb, efficient absorption would predict countercurrent exchange as common mechanism, high vascularized system with a larger surface area

Question 214

Breathing by fish

Answer 214

considered external gills, countercurrent mechanism of gas exchange, flow opposite to that of blood, volume is key to fish breathing high volume, uni-directional, countercurrent flow

Question 215

Breathing by amphibians

Answer 215

primary mechanism is through the skin, gills are important for breathing at the beginning, but diminishes later in life, but skin breathing remains important through the amphibian’s life, mix of water and air breathing, mechanism of breathing changes with life stages

Question 216

breathing by reptiles

Answer 216

primarily air breathers, little gas exchange through skin, single chamber for breathing, all gas exchange is through the surface membrane of this uni-chamber, unidirectional gas exchange, not tidal flow, increased surface area for gas exchange

Question 217

Breathing by mammals

Answer 217

huge surface area - so many divisions, 23 divisions in the lungs, many branches / brachii, flow of gas is convectional and diffusional, last terminal brachii contains alveoli which is where diffusion of gases actually occurs, convectional movement through the upper tracts of the lungs, but lower at the alveoli diffusion takes over

Question 218

Residual volume

Answer 218

what air is left (stale air) after you exhale your maximum breath, helps to prevent a collapsed lung, volume at the end of resting expiration, motionless gas

Question 219

Air exchanged during breath

Answer 219

about 500 mL of air exchanged

Question 220

Site of gas exchange

Answer 220

alveolus

Question 221

Total lung capacity

Answer 221

all of the four volumes added together (TV, IRV, ERV, and RV) typically around 6L of air, because residual volume is so difficult to measure, it becomes difficult to measure total lung capacity, so we often just measure vital capacity

Question 222

Vital capacity

Answer 222

the amount of air that can be breathed in and out of the lungs, the movable air (TV, IRV and ERV), but does NOT include the residual volume because it is too difficult to measure, maximal breath in and maximal breath out

Question 223

Inspiratory capacity

Answer 223

the volume of air that can be inspired, sum of tidal volume and the inspiratory reserve volume

Question 224

Expiratory capacity

Answer 224

the volume of air that can be exhaled, sum of the tidal volume and the expiratory reserve volume

Question 225

Breathing by birds

Answer 225

two air sacs that move air in and out, between the two they have an array of parabronchi where gases are exchanged, cross current gas exchange, tidal gas exchange in and out of the system, air comes into the posterior air sac, air that was already there is pushed through the parabronchi, exhaling - emptying of air sac to the trachea and emptying of the posterior air sac to the parabronchi, uni-directional flow of air through parabronchi

Question 226

Breathing by Terrestrial invertebrates

Answer 226

linked spiracles (openings in the body wall) throughout the body, relatively passive but there are ways to open and close spiracle openings, vascularized for gas exchange through trachea walls, diffusion of gases through trachea

Question 227

Gas exchange in photosynthesis

Answer 227

getting CO2 out of the external medium (air) and into the leaf - usually via diffusion through the stomata, but this allows diffusion of other gases as well, the most important is water movement

Question 228

Diffusion of gases occur based off …

Answer 228

partial pressure gradient between the SAME gas, move from high partial pressure of a gas to a region of low partial pressure of that same gas

Question 229

Hydraulic pressure of leaves

Answer 229

this resistance to water varies depending on growth conditions and water potentials of the leaf (ex. leaves growing in shaded conditions exhibit greater resistance to water flow than do leaves in higher light)

Question 230

Stomata

Answer 230

pore in the leaf surface that allows access from the outside to air spaces inside the leaf, more than 90% of all gas exchange occurs at this sight, can open and close, but while open it is good for CO2 uptake but allows water to leave (bad for water loss)

Question 231

Location of stomata for C3 dicot plant

Answer 231

often found on the under side of the leaf

Question 232

Structure of a monocot stomata

Answer 232

surrounded by thin guard cells with subsidiary cells sitting on each side (epidermal cells surround guard cells)

Question 233

How do stomata open and close

Answer 233

microfibrils can bend but do not stretch, water makes cell swells along the lines of least resistance, regulating in flow and out flow of water and gas exchange through this movement

Question 234

Why would the stomates be closed?

Answer 234

during temporal regulation, the stomata can be closed during the night because CO2 demand is low will little light available and they can also be closed when the soil water is less abundant and therefore the stomata will remain closed or open very little even on a sunny morning to try to minimize water loss and dehydration

Question 235

Why do the cells swell to open the stomata?

Answer 235

water uptake is driven by potassium and chloride influx, solute concentrations increase and therefore water flows into the cells to dilute the solution which increases the tugor pressure of the guard cells causing them to swell

Question 236

Guard cell swelling throughout the day

Answer 236

the potassium and chloride influx initiates this early in the day, over the course of the day after reaching maximum, the gradient across the membrane for potassium almost completely diminishes and then sucrose content builds up through photosynthetic activity and is used to maintain high osmotic state throughout the day - keeps high tugor pressure of the guard cells

Question 237

Guard cells shutting

Answer 237

as sucrose levels drop at the end of the day, the aperture closes (sucrose and potassium levels low)

Question 238

How is stomatal opening and closing regulated?

Answer 238

responds to internal CO2 partial pressure - if carbon dioxide is too low, the stomata will open to allow more carbon diode to diffuse into the leaf, and it closes in response to water stress, also ATPase is light responsive therefore responds to light to influence photosynthetic activity to produce sucrose

Question 239

C4 plant photosynthesis

Answer 239

spatial separation of initial CO2 fixation and the calvin cycle, when CO2 first enters the solution it is modified into HCO3- (carbonic acid), therefore maintaining gradient of CO2 partial pressure, promoting further uptake of CO2, carbonic acid is modified into malate acid and is moved to the bundle of sheath cells where it can build up and be broken down into pyruvate

Question 240

Advantage of C4 plant spatial separation

Answer 240

spatially separating where CO2 enters the cells and where it is actually used maximizes the likelihood of carbon fixation and reduces oxygen competition

Question 241

CAM Plant photosynthesis

Answer 241

temporal separation of CO2 influx and photosynthesis, stomata are open and CO2 can come into the leaf when it is cooler at night, reduces water loss from open stomata at night and then photosynthesis occurs during the day time when the light is available, therefore difference in timing usage of CO2

Question 242

How to maximize oxygen and CO2 movement in the bloodstream?

Answer 242

carbon dioxide reacts with water to become carbonic acid - no longer dissolved gas, therefore PCO2 is lowered and removal of CO2 is larger anymore continuous from the tissues to the blood (larger partial pressure gradient), when oxygen binds to hemoglobin in the blood you can get more oxygen because oxygen is no longer a free gas and therefore PO2 is maintained low

Question 243

O2 Transport-respirtatory pigments

Answer 243

these pigments increase the oxygen carrying capacity of the blood

Question 244

Oxygen binding to iron in a heme molecule

Answer 244

iron is not oxidized (electrons are not exchanged), therefore it can still be reversed when oxygen needs to leave the blood

Question 245

Heme

Answer 245

is a porphyrin ring complexed with an iron atom

Question 246

Myoglobin

Answer 246

monomeric protein with a single heme molecule in muscles

Question 247

Hemocyanins

Answer 247

do not have iron, they are blue and contain copper, they have multiple O2 binding sites, bright blue blood when oxygenated (found in squids and lobsters)

Question 248

Chlorocruorins

Answer 248

have a modified porphyrin ring with iron to bind with oxygen but they are green, they are found in some marine worms

Question 249

Hemerythrins

Answer 249

non-porphyrin but do contain iron proteins that occur intracellularly in muscle and blood cells, they are found in some types of worms and brachiopods

Question 250

Hemoglobin

Answer 250

found in blood and may have up to four heme-globin molecules (subunits), typical pattern is two alpha and two beta globins, shows cooperated binding that alters the O2 binding affinity of other globin molecules - when one subunit binds to oxygen, it changes the conformation of the other globin molecules and therefore increases its affinity with oxygen - 300 x greater for the 4th O2 to bind to the last globin molecule than the first

Question 251

Myoglobin vs. Hemoglobin

Answer 251

myoglobin shows no cooperativity because is is a monomer and always has greater O2 affinity than hemoglobin
at any PO2 where the tissues are, it will bind oxygen greater than hemoglobin, this is important because myoglobin in your muscle cells will always take the oxygen from the hemoglobin and get oxygen into the muscle (one way transport), no matter how low the PO2 will get in the muscles or how hard you are exercising)
animals such as seals and whales that have to dive for long periods of time have very red muscles because they are a high saturation of myoglobin that stores oxygen for later use and can never be lost to hemoglobin

Question 252

P50

Answer 252

measure of the binding affinity of a respiratory pigment of oxygen, the PO2 needed to reach 50% saturation, a low P50 means you have a high binding affinity (less oxygen is needed to reach full saturation)

Question 253

Low P50 environment

Answer 253

not a lot of oxygen in their normal habitat (ex. earthworms that live underground), higher affinity associated to get the oxygen it needs

Question 254

Hematocrit

Answer 254

the fraction of blood volume made up by red blood cells, this can vary and is maximal at about 55% (for birds) and around 45% for humans, used to measure how much hemoglobin is found in the blood cells, the oxygen capacity of the blood

Question 255

Hematocrit testing tube

Answer 255

cells that pack down at the bottom will be the erythrocytes (red blood cells) and platelets, the plasma will pack up at the top of the tube, measured with a ruler to get the fraction

Question 256

Having hematocrit above 55%

Answer 256

it would not be fluid enough to move through the circulatory system effectively, too many red blood cells would reduce the amount of plasma in the blood which carries glucose and takes waste away from the tissues

Question 257

Factors that affect P50 - Bohr Effect

Answer 257

increased carbon monoxide and fetal hemoglobin will cause a shift to the left of the curve and decreased pH (more acidic environment), increased carbon dioxide, increased temperature will cause the oxygen dissociation curve to shift to the right therefore increasing the partial pressure of oxygen needed to saturate hemoglobin

Question 258

Amphibians, Turtles, Lizards and Snakes

Answer 258

three chambered heart and systemic and pulmonary circuits are not completely separated, skin plays a role in gas exchange

Question 259

Amphibian’s Circulatory System

Answer 259

left side of their heart pumps oxygenated blood to the tissues of the body which takes all of the oxygen and then the deoxygenated blood goes from the tissues to the right side of the heart to be pumped to the lungs or to the skin to receive oxygen, but the lungs are more effective in gas exchange, therefore the blood from the heart goes to the left side of the heart to be pumped to the tissues, while the blood from the skin has little oxygen and is pumped through the right side of the heart circuit again

Question 260

Turtles, Lizards and Snakes’ Circulatory Systems

Answer 260

left side of the heart pumps blood to the skin and to systemic tissues and the oxygenated blood of the skin joins with the deoxygenated blood of the systemic tissues to be pumped through the right side of the heart to the lungs to be oxygenated there, they also have a septum which is like a wall on each side of the skin’s blood flow

Question 261

Right-Left and Left-Right shunts

Answer 261

dividing of the blood flow between the two sides of the heart by shutting off the blood flow to the lungs when animals dive under water and have to hold their breathe, and therefore the pulmonary flow is diverted to the skin where gas exchange must occur and to the systemic tissues, turning off this shunt will allow blood to go back to the lungs

Question 262

Right systemic aorta and right-left shunts

Answer 262

right systemic aorta is another blood vessel that leaves the right side of the heart and joins with the flow of the left side of the heart, they are connected by a valve known as the Cog valve and this Cog valve is open when they dive and shut off the right side of their heart, therefore both sides of the heart will pump to the systemic circuit

Question 263

Invertebrates with closed circulation

Answer 263

octopuses and squids have closed circulatory systems with three hearts - two brachial hearts, and one systemic heart, blood contains hemocyanin (blue protein in blood that contains copper), blood goes to the gils to receive oxygen and then rejoins the blood from the body again

Question 264

Invertebrates with open circulation

Answer 264

arteries do not go to capillary beds, they flow into large sinuses (open cavities) that directly bathe the organs and tissues to provide oxygen, they have very low resistance therefore high flow is achieved and this is effective

Question 265

Crustacean’s heart

Answer 265

one chambered heart with an ostia (one way valve) that opens and closes for blood flow

Question 266

Crayfish’s circulatory system

Answer 266

cor frontale (another, smaller heart) that ensures good blood flow to the nervous system and the heart

Question 267

Insect’s circulatory system

Answer 267

has nothing to do with oxygen transportation, it is only used for the transportation of waste and fuel

Question 268

The Mammalian heart

Answer 268

2 atria (thinner walls), 2 ventricles (thicker walls due to higher pressure to withstand), 2 atrioventricular valves and 2 semilunar valves of the aorta and the pulmonary artery, left side of the heart receives oxygenated blood from the pulmonary vein and delivers the blood through the aorta to the tissues of the body, the right side of the heart receives deoxygenated blood through the inferior or superior vena cava and then delivers deoxygenated blood to the lungs through the pulmonary artery

Question 269

isovolumetric

Answer 269

the pressure is not large enough to open the valves to let the blood leave, therefore it is the same volume but the pressure is building up

Question 270

Five Stages of the Cardiac Cycle

Answer 270

1. atrial systole (atria contracts)
2. early ventricular systole (isovolumetric ventricular contraction)
3. ventricular systole (rapid ejection period - blood phase)
4. early ventricular diastole (isovolumetric ventricular relaxation)
5. late ventricular diastole (ventricular filling)

Question 271

Systole

Answer 271

contraction of the heart

Question 272

Diastole

Answer 272

relaxation of the heart

Question 273

Cardiomyocytes

Answer 273

gap junctions are intercalated discs between these cells, and these cells sit at a relatively negative charge and when one depolarizes, all those connected to it will also depolarize because of the gap junctions connecting them and also because their membranes are quite leaky to the electrical charges

Question 274

SA Node

Answer 274

spontaneously depolarizes, this is known as the pacemaker of the heart because its speed of contraction dictates the speed of the rest of the heart, this depolarization spreads rapidly among the cells of the aria causing contraction of the atriums and this signals the AV node to spread the signal down the bundle of HIS to do to the very bottom of the ventricles and contract the ventricles from bottom up

Question 275

Movement of fluids through the xylem

Answer 275

negative pressure used to pull fluids through the xylem

Question 276

Movements of fluids through the phloem

Answer 276

osmotic pressure / positive pressure to push the fluid through the xylem

Question 277

Osmotic Potential

Answer 277

osmotic potential is based on overall solute concentration, osmotic adjustment means changing solute concentration to change water potential

Question 278

Water cannot be moved …

Answer 278

actively!

Question 279

Movement of water

Answer 279

water movement requires protein channels called aquaporins - can be regulated to control water movement, water follows the overall solute gradient (from areas of high to low solute concentrations), no energy expended

Question 280

Moving water requires …

Answer 280

the creation of a solute gradient, some ion pumps that only work in one direction to create gradient (uniporters), semipermeable membranes are an essential factor, drives the influx of water

Question 281

Water movement by osmosis

Answer 281

water moves to the side in which has the most solute in order to equilibrate the sides by diluting that side, across a semipermeable membrane to water

Question 282

Isotonic osmotic system

Answer 282

active influx of ions creates equal solute concentrations across the membrane, solutions inside and outside are considered isotonic - this will cause water to move in both directions, but there is no NET movement of water (Note: these do not have to be the same solutes to maintain isotonicity, isotonic solution)

Question 283

Water moving down a pressure gradient

Answer 283

water potential is influenced by gravity, dissolved solutes and effect of hydrostatic pressure, and water normally moves towards the lower (more negative) water potential

Question 284

Where do cells get the water in plants?

Answer 284

roots and metabolic water (carbs and fats produce large amounts of water, protein = less)

Question 285

Q (flow rate) =

Answer 285

difference in pressures of two areas divided by the resistance (delta P / r)

Question 286

Resistance of the tubing is impacted by …

Answer 286

the viscosity of the medium, the length of the tubing and the radius of the tubing (having the most impact)

Question 287

Xylem

Answer 287

translocates water and inorganic nutrients from the roots to the leaves

Question 288

Phloem

Answer 288

translocates sugars, proteins and signalling molecules from source tissues (do make their own sugars) to sink tissues (do not make their own sugars), therefore bi-directional

Question 289

Xylem are made up of …

Answer 289

tracheids and vessels elements - these are cells that are dead at maturity because they require the production of secondary cell walls and this requires death before production

Question 290

Vessel Elements

Answer 290

primary vessels in angiosperms, end to end stacking plus perforation plates known as pits that connect the vessel elements laterally, some lateral movement of water, but it is slow compared to vertical movement of the water, tend to be shorter and wider than tracheids

Question 291

Tracheids

Answer 291

primary vessels in gymnosperms, they are elongated cells arranged in overlapping vertical files and contains pits where there is low resistance and a lot of lateral movement of water

Question 292

Cohesion-Tenson Theory

Answer 292

evaporation at the leaves causes negative pressure, the cohesive properties of the water molecules transfer this tension though the length of the water column, water at the top of a tree develops a large tension (a negative hydrostatic pressure) and this tension pulls water through the xylem

Question 293

Safety-Efficiency Trade Off

Answer 293

wider vessels create efficient transportation but takes up much more room than thinner vessels and therefore larger impact from an embolism (air bubble) affecting more of the vessel and overall transportation than an embolism in a thin vessels

Question 294

Large tubing in plants

Answer 294

often occurs in the summer when there is a lot of water available, but in the winter when there is little water available, they will adapt to smaller tubing and more of them

Question 295

Direction of xylem’s fluids

Answer 295

roots to leaves

Question 296

Direction of phloem fluids

Answer 296

source to sinks

Question 297

Mechanism of transportation of xylem

Answer 297

transpiration and cohesion-tension (negative hydrostatic pressure pulling the fluid from the roots up to the leaves)

Question 298

Mechanism of transportation of phloem

Answer 298

bulk flow (movement of water and all solutes in it)

Question 299

Phloem

Answer 299

living cells, contain sieve cells connected by sieve plates and they are connected with companion cells, direction of flow is always from source to sink (depending where the energy and water is needed in the plant)

Question 300

Sieve elements cells

Answer 300

basically water-filled tubes, do not contain a nucleus, vacuole, filaments or ribosomes, key feature is that they are under high tugor pressure (lots of solutes present), between the sieve element cells are holes known as sieve plates that connect them

Question 301

Companion cells

Answer 301

phloem loading and unloading - these are the metabolically active cells, ATP production and protein synthesis occurs, at the end of the sieve elements

Question 302

Phloem loading

Answer 302

at the source end, phloem loaded with sucrose by companion cells at source tissues - may be symplastic (passive) or apoplectic (active transport), phloem is loaded with solutes therefore the water from xylem flows to the phloem and this builds up quite a significant pressure (tugor pressure) water moves from high to low pressure

Question 303

Phloem unloading

Answer 303

at the sink end, the solutes are pulled out of the phloem to be used therefore bulk flow of water and solutes from high to low pressure (pressure driven) out of the high pressure of the phloem to the low pressure of the source cells, lower tugor pressure results

Question 304

Maintaining Concentration gradient in symplastic loading of the phloem

Answer 304

largely passive diffusion that occurs because of polymer trapping - in the bundle of sheath cells there is a build up of sucrose and this diffuses into the companion cells where sucrose is converted into a different polymer, therefore sucrose cannot equilibrate between the two sides, continuous movement of the water from the xylem to the phloem, uniporter for sucrose therefore uni-directional because sucrose is modified and no longer sucrose

Question 305

How does water get into the plant

Answer 305

the growing tip of the plant is where the rate of water uptake is highest, most efficient

Question 306

Root hairs

Answer 306

high surface area and therefore increases absorption efficiency at the roots

Question 307

How can plants alter nutrient availability?

Answer 307

soil particles tend to have negatively charged surfaces to which cations bind - the plant pumps hydrogen ions (via proton pumping) in order to displace nutrients cations from colloids allowing their uptake, some nutrients are more available (more soluble) in acidic solutions therefore roots can extrude protons to acidify the soil solution and make nutrients soluble

Question 308

Mobile nutrient deficiency

Answer 308

ex. is a nitrogen deficiency, when the plant does not receive enough of this nutrient from its soil, it pulls it from the oldest leafs therefore the lower leaves die first

Question 309

Immobile nutrient deficiency

Answer 309

ex. is a calcium deficiency, plant will pull the nutrient from the newest, younger leaves, therefore the leaves higher up will die first

Question 310

Where is most of the water found in the body?

Answer 310

the human body is filled with about 60% water and most water is found as intracellular fluid (surrounded by a membrane)

Question 311

Kidneys filter the blood …

Answer 311

glomerulus filtration at about 170 L per day, balance between water going into the body and extraction through urine, feces, breathing, etc …

Question 312

Water of the body contains …

Answer 312

inorganic ions, organics ions and proteins that exert osmotic pressure

Question 313

Importance of ion concentrations

Answer 313

ions in the right concentration are needed across membranes for specific gradients and physiological work (ex. nerve function and muscle contractions)

Question 314

Cells regulate ions and osmotic pressure through ..

Answer 314

their membranes - channels, exchangers, pumps, aquaporin, and diffusion and leakage of ions

Question 315

Endothelium

Answer 315

is the outside layer of the capillaries and this can vary in composition, tightness and leakage and can contain fenestrations which are holes that allow ions to pass in and out of the capillaries

Question 316

Difference in ion concentration and osmotic pressure between plasma and interstitial fluid

Answer 316

often not much difference in ion concentration and osmotic pressure between the plasma and the interstitial fluid because they can freely exchange and therefore regulating one gets regulation of the other

Question 317

Uniqueness of water breathers and their kidneys

Answer 317

a high amount of water is filtered because of low oxygen concentration in water and therefore there is a lot of water and salt exchange in water breathers through their gills

Question 318

Movement of solutes and water

Answer 318

concentration gradients drives ion movement through diffusion and water moves through osmosis

Question 319

Regulating and conforming to osmolarity

Answer 319

osmolarity takes into account the ion concentration and volume of water in blood and cells, volume of blood is often kept constant, osmotic pressure however can be modified, some animals keep this closely regulated, others can afford to conform their osmolarity and some animals go between regulation and then switch to conformity at a point outside of their zone of tolerance

Question 320

Major osmotic, ionic and volume regulators of the blood

Answer 320

kidneys, gills and the skin

Question 321

Judgement of kidney concentrating ability

Answer 321

can be judged by urine:plasma ration (U/P ratio)

Question 322

U/P ratios and meanings

Answer 322

if the kidney concentration is lower than 1 it will be almost clear (dilute) because there is more water in the urine than there is solutes, but if the kidney concentration is higher than 1 it will be very concentrated and dark because there is less water relative to the solutes than plasma

Question 323

What U/P do we want

Answer 323

we want a U/P or kidney concentration of 1 where the urine concentration is equal to that of the plasma concentration, this is isomotic

Question 324

U/P less than 1 =

Answer 324

hyposmotic

Question 325

U/P greater than 1 =

Answer 325

hyperosmotic

Question 326

Cell volume regulation

Answer 326

changes in extracellular osmoticity (tonicity) can cause changes in cell size, cells compensate by changing their internal solute content, osmo-regulators will cause their cells to regulate volume by altering the concentration of the organic solutes (ex. amino acids) rather than ions because ions can hinder gradients needed for function

Question 327

Living in water - fresh vs. salt water

Answer 327

major ions founds in sea water - huge difference in sodium and chloride and many other ions from sea water to fresh water including magnesium, sulphate, calcium, potassium and bicarbonate

Question 328

Fresh water

Answer 328

fresh water animals are hyperosmotic to their environment - they gain water and lose ions, large osmotic and sodium gradients from inside to outside therefore salt is lose through diffusion and water is gained through osmosis

Question 329

U/P ratio of fresh water organisms

Answer 329

well below 1 because constantly gaining water

Question 330

How do fresh water organisms gain and loose salt and water?

Answer 330

(1) through what they eat
(2) actively takes up sodium and chloride through symporter of the gills and skin, this requires ATP to go against gradient (but passively looses it through diffusion)
(3) salts and water in feces is lost
(4) water enters through diffusion

Question 331

divalent ions

Answer 331

those retained by the gut and kidneys

Question 332

monovalent ions

Answer 332

sodium and chloride retained at gills

Question 333

Salt water

Answer 333

some marine animals are isosmotic and nearly isotonic to their environment or hyposmotic, to the sea water, very high sodium and chloride concentrations especially

Question 334

Salt water organisms

Answer 334

hyposmotic to their environment means they lose water and gain ions (salts), salt water organisms can drink the water and use it to rehydrate, salts are lost in feces and some in urine, NaCl from the water is going to enter the body and then there is active extrusion of Cl and active or passive outflow of sodium back into the water

Question 335

Gill NaCl excretion for sodium

Answer 335

gills excrete NaCl against their concentration gradient to maintain internal ionoregulation, NaK - ATPase pumps out 3 sodium and 2 potassium enters (on the basolateral side of the membrane), the only way sodium enters the body is through the sodium chloride symporter

Question 336

Gill chloride excretion

Answer 336

mitochondria ridge cells (chloride cells) concentrate a lot of chloride ions and this high concentration of chloride drives the movement of chloride out of the cell and into the ocean, rectal gland can secrete lots of chloride

Question 337

Junctions of the cells of the gills

Answer 337

pretty tight between the cells, but they do actually allow sodium to passively go through to the ocean

Question 338

How can salt water organisms alter ion movement in and out of the cell?

Answer 338

selectively locate transporters / exchangers to generate gradients and position the channels on the apical or basolateral (basement) membrane

Question 339

NaKClCl co-transporter

Answer 339

1 Na, 1 K and 2 Cl molecules in this transporter, all of which must be present in order to function and get all of these molecules out of the cell

Question 340

What gets the large amount of chloride into the cell?

Answer 340

the sodium gradient allows for the chloride to build up in the cell and leave through the co-transporter of NaKClCl

Question 341

How is urea used to prevent dehydration and movement of ions in some salt water animals?

Answer 341

lower sodium and chloride concentrations than sea water, therefore hypoionic, but also is hyperosmotic because urea is in high concentration in the body as it build up, allowing urea to build up prevents water loss from the body because it eliminates the water gradient between the fish and the ocean, they retain urea as an osmolyte, and make hyposmotic urine (slightly dilute)

Question 342

Problem with urea

Answer 342

not very good with proteins, tends to denature the proteins

Question 343

How to fix the problem with urea

Answer 343

some animals produce trimethylamine oxide (TMAO) as a protective organic molecule to counteract the negative effects of urea on protein structures, ideal ratio between urea and TMAO is 2:1

Question 344

Salt glands

Answer 344

many non-mammalian marine vertebrates eliminate salt by salt glands, kidneys do some work, but still a lot of salts coming in, located above the eyes, on top of the head, contains lobes each with a canal, actively secretes NaCl, fluid drains out of the nasal cavity

Question 345

Marine reptiles and salt regulation

Answer 345

almost double the concentration of sodium and chloride then sea water in their salt gland extraction

Question 346

Living on land and salt regulation

Answer 346

terrestrial animals must balance their water budge, income = loss + storage, air can be very dry, therefore these animals after often at higher risk for dehydration, balance is key, income = eating, drinking, metabolic water, and loss = evaporation, urine, feces and salt glands, storage = bladders, lymph

Question 347

Different loads of osmolytes in food

Answer 347

if it has a lot of water but also a lot of protein they will have to secrete nitrogen waste and will lose some water, if the food is high in salt it is the same thing (lose more water in your urine to balance out the high salt)

Question 348

Free water

Answer 348

is available for drinking, larger animals generally can range farther and go longer between drinks (lower water losses), frogs can absorb water through their skin of the pelvis (don’t have to drink)

Question 349

Metabolic water production

Answer 349

produced from the oxidation of fuels - more water produced from lipids, little from carbs and proteins

Question 350

Cutaneous evaporative water loss mainly determined by …

Answer 350

layers of lipids and waxes deposited in the epicuticle of the skin and therefore more resistant to water loss with more lipids and waxes (prevents water loss more)

Question 351

Why do we have a natural gradient to loose water?

Answer 351

air around us is not usually 100% saturated with water, but our body is at 100% usually and therefore there is this natural gradient for water to leave our body, the higher the humidity of the environment the greater the gradient and therefore the greater the water loss

Question 352

Environment’s influence on exoskeleton

Answer 352

the more dry the environment, the more resistant that the exoskeleton will be to water loss therefore more wax and lipids in the layers of the skin

Question 353

Temperature’s impact and limit on cutaneous evaporative water loss

Answer 353

cutaneous evaporative water loss is affected by temperature depending on the temperature when the lipid transitions from a solid to a liquid phase, however when lipids melt and transition to a liquid phase they can no longer prevent water loss at this high temperature and therefore this is the limit

Question 354

Water loss and humidity

Answer 354

higher temperature = higher ability of the air to be able to hold water in the vapour phase, the amount of water that air can hold doubles ever 11 degrees

Question 355

Respiratory evaporative water loss

Answer 355

depends on the difference in temperature and saturation of inhaled and exhaled air, if you breathe in cold air, even if it is fully saturated it will be increased in temperature in the lungs and therefore its ability to hold water increases and when it is exhaled it actually takes water out of the lungs and therefore you actually lose water

Question 356

Preventing water loss with cold air ..

Answer 356

this water loss can be prevented by cooling the exhaled air, this is done by using your sinuses (on the EXHALE), inside the nasal cavity there are convoluted air passages specialized for exchanging heat and water with the environment, countercurrent heat and water exchange

Question 357

Animals that are more efficient at cooling down the air they exhale and preventing water loss

Answer 357

smaller mammals

Question 358

Total evaporative water loss

Answer 358

total mass specific rate of evaporative water loss is related to body weight due to differences in relative surface area and metabolic rate

Question 359

What animals have a higher total evaporative water loss?

Answer 359

smaller animals have much higher relative water losses for their body size because cutaneous water losses are high because larger surface area for volume of their body and they have a relatively higher metabolic rate and greater oxygen consumption - breathe more for their size and therefore lose more water through respiration

Question 360

Weight Specific total evaporative water loss

Answer 360

total mass specific rate of evaporative water loss varies among phylogenetic lineages and is lower in xeric adapted species
animals living in water for some times (ex. crabs) loose a lot of water, amphibians have pretty high water losses because skin is needed for gas exchange (water leaves through the skin - more permeable to water), reptiles are very well adapted to living in hot, dry environments and have very little water loss
mice, rats and birds have low water losses
animals that live in aquatic environments have high water loss and animals living in desserts have very low

Question 361

Fecal water loss

Answer 361

fecal water loss is greater for animals that each less digestible diets (ex. herbivores > carnivores)
more digestible diets result in less water loss because of less fecal produced (ex. high end dog food vs. cheap)

Question 362

Urinary Water loss related to…

Answer 362

U/P ratio, salt intake, protein intake and the type of nitrogenous waste produced

Question 363

Larger U/P ratio and water loss

Answer 363

greater U/P = more water saved (concentrated urine)

Question 364

High salt diet =

Answer 364

more salt in the food that the body does not need is going to be excreted and water is attracted to the sodium therefore leaves as well

Question 365

High protein diet =

Answer 365

more water loss, more nitrogenous waste

Question 366

What animals make more concentrated urine? Why?

Answer 366

smaller mammals make more concentrated urine than larger mammals because kidneys are selected to make more concentrated urine because they already lose so much water

Question 367

Dessert adapted animals and urine

Answer 367

dry adapted species are especially good at producing concentrated urine (more than the aquatic animals who have a lot of water available)

Question 368

Amino acids and the urine

Answer 368

amino acids that are no longer needed because you have enough are deaminated, taking the nitrogen off and this requires water to be excreted from the body, but the amount of water needed depends on the nitrogenous base

Question 369

Most common nitrogenous bases are ..

Answer 369

NH3 (ammonium) which does not require further energy but is very toxic and water soluble therefore can not let it build up and therefore NH3 is converted to NH4

Question 370

Carnivores vs. Herbivores and water loss

Answer 370

carnivores tend to lose more water in their urine but less in their feces because of high protein, but herbivores have low water loss in urine but high in feces (still greater than carnivores)

Question 371

Ammonotelic animals

Answer 371

boney fish can afford to produce a lot of ammonium because they can dump a lot through their gils

Question 372

Ureotelic animals

Answer 372

some reptiles, sharks and mammals only make urea

Question 373

Uricotelic animals

Answer 373

uric acid is the end product, very concentrated urine, process done after kidneys in the gut

Question 374

Water storage in different animals

Answer 374

toads and turtles store isosmotic or hyposmotic urine in the bladder
can bring the water from the bladder back into the body if the toad or turtles get too dehydrated
ostriches store water in the coprodeum (no bladder) which can expand highly and can draw water back into their body if they get dehydrated
some frogs can also store water in their lymph (Australian water-holding frog)

Question 375

Kidney function in mammals

Answer 375

nephrons are microscopic tubules that ultrafilter plasma (blood) and modify the ultrafiltrate by reabsorption of needed solutes (ex. salts, glucose, amino acids) to make urine as the end product, filter blood so that what is left is the nitrogenous bases and water of the urine

Question 376

ultrafiltration of mammals

Answer 376

takes places in the renal corpuscle, involves filtering the blood from the glomerulus (anatomoses of blood vessels into capillaries, arterial blood) and small things from the blood of the glomerulus get through the fenestrations of the walls of the Bowman’s capsule

Question 377

ultrafiltration is driven by …

Answer 377

hydrostatic pressure in the glomerulus leading to bulk flow of primary urine, high blood pressure of the capillaries of the glomerulus squeeze fluid through to the Bowman’s capsule, high and low blood pressure also influences the function of the kidneys

Question 378

PCT of the nephron

Answer 378

reabsorbs most of the ultrafiltrate and key solutes to go back into the blood

Question 379

DCT of the nephron

Answer 379

differentilly reabsorbs water to set the final urine concentration