Quiz 1 Flashcards
1
Q
Physiology
A
- how things work
- the biological study of the functions of living organisms and their parts
- the study of how cells interact with their environment to obtain the things required for life (vital substances ex. water, salts, oxygen, nutrients, heat)
2
Q
external environment
A
- outside of the organism
- barrier between internal and external is the skin/integument
- cells interact through exchange processes
- organisms interact with external through exchange systems
3
Q
exchange systems
A
- any system that allows for the exchange of material (vital substances) from external environment to internal environment or internal environment to external environment
- ex. respiratory system (O2/CO2), digestive system (nutrients/H2O), urinary system (excretion/H2O), circulatory system (distribution)
4
Q
organization of complex biological organisms
A
- cellular level- (four general cell types)- epithelial, connective tissue, nerve, muscle
- tissue level- (groups of cells with common structure and function) ex. muscle tissue
- organ level- (organization of different tissues to perform specific functions) ex. heart
- system level- (several organs organized carry out major body functions) ex. cardiovascular system
5
Q
basic principles
A
- all life is:
- aquatic
- compartmentalized
- deals with same fundamental problems
- constrained by laws of physics and chemistry
- can tolerate only a limited range of conditions
6
Q
All life is aquatic
A
- body fluids of all animals have the same general composition
- H2O and salts (very much like sea water)
- water is the major component and is 75% of body weight and 99% of all molecules (in humans)
- salts (simple inorganic substances)- .75% of molecules are salts (Na+, K+,Cl-)
- biochemical substances (proteins, nucleic acids, etc.)- .35% of molecules
- all life is maintaining an internal aquatic environment for the cells (cells are aquatic)
7
Q
all life is compartmentalized
A
- separation of substances in different compartments
- the cell- the basic unit (compartment)
- the major fluid compartments inside organisms:
- intracellular fluid (ICF)- inside of cells
- extracellular fluid (ECF)- outside of cells
- interstitial fluid- ECF that is not in the circulatory system
- plasma- liquid portion of blood (ECF)
8
Q
Sodium
A
- high concentration in ECF
- low concentration in ICF
9
Q
Potassium
A
- low concentration in ECF
- high concentration in ICF
10
Q
Calcium
A
- low concentration in ECF
- very low concentration in ICF
- a lot of energy is being expended to achieve this -> this is bc Ca is very important to the cell
11
Q
asymmetries between compartments are essential for physiological processes
A
- a fundamental challenge for all organisms is how to maintain asymmetry
- cells expend energy to maintains these asymmetries
- hard to transport substances selectively between compartments -> requires energy and trade offs
- trade offs- lose H2O during respiration, lose H2O during thermoregulation
12
Q
all life deals with the same fundamental problems
A
- many animals have solved fundamental problems in interesting ways
- can gain unique and distinctive insights by looking at different animals
- comparative physiology
- all life requires the input of energy
- life is energetically unfavorable (need energy to survive)
- > every organisms has asymmetries and compartments that require energy in order to maintain
- another ex. reproduction which requires energy
13
Q
Adenosine triphosphate (ATP)
A
- principal form of energy used by cells
- hydrolyzes ATP to ADP which allows us to do cellular work
- food energy is required to make ATP
- ATP is made during cellular respiration (mainly from glucose)
- glucose is broken down aerobically (oxygen)- CO2 + H2O + 38 ATP -> more efficient, and anaerobic (no oxygen)- lactic acid + 2 ATP -> faster
- aerobic metabolism is more efficient
- oxygen intake can be measured and predict how much energy an organism is making and expending
- aerobic metabolism allows of animals living in dry environment to produce H2O
14
Q
metabolic rate (MR)
A
- the amount of energy an animal uses in a unit amount of time
- measured as O2 consumption in units of calories or kilocalories (1000 cal)- because O2 is proportionate with the amount of ATP is needs to generate and expend
- sum of all energy requiring biochemical reactions:
- basal metabolic rate
- movement
- heat production
- anabolic pathways (building biomass)
- MR is not constant and is never zero
- higher the MR higher the heat produced
15
Q
all life is constrained by the laws of physics and chemistry
A
- ohm’s law
- boyles law
- ideal gas law
- gravity
- kinetic & potential energy
- intertia, momentum, velocity, & drag
- physical environment governs what cells can and cannot accomplish
- cells can utilize these laws to their advantage ex. signaling
16
Q
size principle- relationship between surface area and volume
A
- size of animal matters
- ex. of how life is constrained by the laws of physics and chemistry
- as the radius gets bigger, the SA/V ratio gets smaller and relative surface area for exchange decreases
- therefore, a larger animal will lose more heat to the environment than the smaller animal bc it has more SA -> but the larger animal will have more cells (volume) to generate more heat
- the smaller animals is losing more heat in proportion to the heat it is able to generate bc it has a smaller SA to V ratio
- large animal- low heat exchange and good heat retention
- small animal- high heat exchange and poor heat retention -> gets hotter and colder faster
17
Q
All life can tolerate only a limited range of conditions
A
- referring to the internal environment*
- salts, H2O, O2, CO2, nutrients, waste elimination, temperature, pH
- the process of maintaining these conditions within tolerable ranges is called homeostasis
- homeostasis- maintenance of a relatively constant internal environment- requires cell-to-cell communication (nervous system, hormonal system, intrinsic system) and requires negative feedback
18
Q
Feedback systems
A
- all feedback systems have the following components:
- sensor- measures some aspect of the internal environment (ex. temp)
- integrator- compares the sensor measurement to a reference value (set point) (ex. normal temp)
- effector- the output of the system that changes the internal environment (ex. increases temp)
- ex. sensor detects temp -> integrator compares temp to set point -> decides its too warm -> effector lowers the temp
- a decrease in the sensor measurement has the same effect on the output of the system as an increase in the set point
19
Q
negative feedback
A
- response is opposite to the stimulus
- maintains the set point
- effector counteracts (is opposite to) the initial sensor stimulus
- critical for maintaining homeostasis
20
Q
positive feedback
A
- the effector increases the initial sensor stimulus
- leads to rapid change
- an increase in temperature measured by the sensor results in the effector causing a further increase in temperature
- ex. giving birth, blood clotting, fever, *action potential- depolarization of the cell leads to more depolarization
21
Q
physiological ecology
A
- the organisms relationship to its physiochemical environment
- goal- understand how organisms use the basic law of physics and chemistry to meet their biological needs and solve basic physiological problems
- essence of comparative physiology- how different organisms solve the same problems with different environments
1. body temperature and temperature regulation
2. water and ion balance
22
Q
Energy utilization
A
- inject macromolecules
- break down into energy (ATP)
- cellular work, biosynthesis, external work
- all of these processes produce heat bc they are inefficient (some energy is lost to heat)
- *energy utilization is a source of heat (endogenous)
23
Q
Nitrogenous wastes
A
- ingested foods include proteins, carbohydrates, and fats
- the end products of ingested food are typically CO2 and metabolic H2O
- Metabolic breakdown of proteins also produces ammonia (NH3) (nitrogenous wastes)
- nitrogenous wastes are: salvaged for amino acid synthesis, excreted (high levels of ammonia are lethal), and in some animals, converted to less toxic forms of nitrogen (urea, uric acid)
- *trade offs: it takes energy to convert nitrogen, water must be sacrificed in order to excrete nitrogen
24
Q
Conversion of nitrogen trade offs
A
- leaving it be- no energy required, requires a lot of water to eliminate (.5 L per g of nitrogen), ammonotelic
- urea- less toxic (can be stored), requires energy, requires .05L of water per g, ureotelic
- uric acid- requires little water to eliminate, requires energy, .001L of water per g, uricotelic
- aquatic animals are commonly ammonotelic, mammals and marine mammals are ureotelic, birds are uricotelic
- ammonia > urea > uric acid -> solubility
25
Heat
heat is kinetic energy (molecular motion)
26
temperature
- an index of molecular motion (average kinetic energy)
- Hot- high heat content, high energy content, high molecules motion, high temperature
- Cold- low heat content, low energy content, low molecular motion, low temperature
27
endogeneous heat
heat originating from the organism
| -comes as a by product from chemical processes (biosynthesis, etc.)
28
Thermal budget
- energy sources vs ways energy leaves the animal
- in and out should be equal
- heat can transfer through: conduction, convection, evaporation, radiation
29
Heat transfer: Conduction*
- heat transfer through physical contact (solids, liquids)
- T1=T2- no net transfer
- T2>T1- net flow from T2 to T1
- T1>T2- net flow from T1 to T2
- factors that influence heat conduction:
- temperature gradient is driving force
- surface area of contact influences ease of movement
- length between objects influences ease of movement (thickness)
- composition of interface influences ease of movement (thermal conductivity ex. metal)
30
transport equation
dQ/dt= K*A/l * (T2-T1)
- dQ/dt- net rate at which heat is moving (flow of heat)
- K*A/l- ease of movement
- (T2-T1)- difference in temp, driving force
- A- surface area
- l- length between objects
- K- thermal conductivity
31
Exchange of heat between blood and environment
- heat from blood through interstitial fluid and skin to the air
- SA of skin and vessels
- l- space between blood and air
- K- basically water
- vasodilation- enlargement of vessels make them closer to the skin and makes flow of heat easier and larger (decreases l)
- vasocontriction- vice versa
- > passive process
- > increase heat exchange
32
Heat transfer- convection
- occurs when environmental medium (air or water) moves over the body surface
- modified version of conduction (slower)
- transfer equation essentially the same as for conduction
1. free convection- environmental medium not mechanically moved (passive movement (hot air rises, convective currents))
2. forced convection- environmental medium physically moved
33
free convection
- boundary layers- form when there is little or no forced movement of environmental medium
- decreased driving force for heat exchange
- because of boundary layers body senses environmental temperature as 35, not 20 degrees
34
forced convection
- physical movement of environmental medium disrupts boundary layers
- without boundary layers, body senses true environment temperature of 20 degrees (wind chill)
- turning on a fan, breeze, running
- good on a hot day bad on a cold day
35
Heat transfer: evaporation
- transformation of water from liquid to vapor (gas)
- requires energy cools down environment
- 1g H2O -> 580 cal (heat of vaporization)
- evaporative cooling- when water moves from liquid phase to vapor phase, it absorbs energy from the body surface -> cooling
- takes heat from body to go from liquid to vapor
- does not relate to the heat equation
- sweating, panting
36
Heat transfer: radiation
- without contact
- longer wavelength- less energy
- anything that has heat sends out electromagnetic radiation
- can be absorbed or reflected back into the environment
- night vision goggles pick up on heat
37
Heat in
- heat gain from ext. env.
- conduction
- convection
- radiation
- endogeneous heat prod.- comes from chemcial processes
- metabolic rate
38
heat out
- heat loss to ext. env.
- conduction
- convection
- radiation
- evaporation
39
counter-current exchange
-flow on one side is opposite to the flow on the other side -> maximize heat transfer
Bird on ice ex.
-arterial blood on its way down warms the venous blood going back up to the heart
-by the time the arterial blood is down to the feet it is already cool from warming the venous blood -> less driving force
-small driving force for heat exchange from foot to ice- minimal heat loss to environment
40
Core Body temperature
- organisms priority is to maintain core temp
- humans- core T ~ 37C
- birds ~ 39
- extremedies matter less than core bc they can be heated on way back
41
why regulate temp
- chemical reactions are temperature sensitive
- enzymes need a specific temp
- reaction rate of virtually every process in the body increases exponentially with temperature
- proteins denature at too high temps
42
Ectothermy
- use of external heat to thermoregulate poikilotherms (older terminology = variable Tb)
- cold blooded
- all non vertebrate species (amphibians/reptiles/fishes/sharks)
- proportional- temp varies with environment
- MR varies with environment- at low temp they use less energy (slower), at high temp they use more energy (faster) -> it has a optimal MR and T
- rely of behavioral thermoregulation mainly
43
endothermy
- use of internal heat (MR) to thermoregulate hemeotherms (older terminology= constant Tb)
- warm blooded
- birds/mammals
- tunas/dinosaurs
- energetically very costly
- independent- temp is constant and independent of environment (negative feedback)
- driving force between environment and body temp
- As environment get colder the MR increases to maintain temp and at high temp MR also increases bc sweating requires energy (backward J trend)
- utilizes endogenous heat protection in order to thermoregulate
44
heterothermy
- use of both internal and external heat to thermoregulate
- temporal heterothermy
- regional heterothermy
45
Thermo acclimation
- optimal and maximum critical temp can shift depending on season
- optimal MR doesnt change
46
thermoneutral zone
- the range of ambient temperatures that thermoregulation does not need to rely on increasing MR
- thermoregulate without having to generate more heat:
- vasodilation, constriction
- behavioral mechanisms
47
Advantages of being an ectotherm
- requires less energy
- can exploit a broader range of body sizes/shapes
- more efficient in producing biomass
48
Ectotherms: require less energy
- endotherms require ~17x more energy
- more suited to variations in food supply
- can tolerate a less predictable environment
- do not need to produce endogenous heat
49
Ectotherms: can exploit broader range of body sizes/shapes
- since body temp = environment there is freedom from heat conserving constraints
- ectotherms can function with much smaller body masses than endotherms
- greater length/diameter variability in ecotherms
50
Ectotherms: more efficient in producing biomass
- ingested food/energy available for producing biomass rather than maintaining high body temp
- ex. reproduce more babies
51
Behavioral Thermoregulation ex.
-selecting temperature by behavior
FISH
-place a goldfish in a tank with cold on one side and hot on the other
-first the goldfish will explore
-it will find its optimal temperature zone where metabolic rate is optimal
-selecting temperature by behavior
LIZARD
-the lizard will sit on rocks to increase its body temp and MR due to the ambient heat from the rock and sun (the lizard temp will be higher than the ambient temp bc the rock)
-the temperature fluxuates bc it leaves the rock to explore
-at night it burrows to minimize heat loss
52
heliotherm
heat source is the sun
53
thigmotherm
heat source is the substrate (earth) ex. rocks
54
thermoaclimation
- animal cant navigate its environment in order to thermoregulate bc of seasonal extremes
- biochemical changes in the body
- maximum critical temp will change by season (higher in summer)
- biochemically changes to function better in the winter time
- selective synthesis of multiple forms of the same enzyme (produces different enzymes in different seasons) -> isoenzymes- have different optimal temperatures and function at different rates at different temperatures
55
Acute response in ambient temperature
- temp drop -> rapid drop in MR (vice versa)
- fish becomes very slow
- what happen immediately when temp changes
- quick
56
Chronic response in ambient temperature
- slow increase in MR
- curve is shifting left
- acclimation
- if we put a fish in cold water the acute response will be first but if you leave it there over time (weeks) MR will slowly increase (chronic response)
- shifting set of isozymes
57
Thermoregulation in endotherms
- behavioral thermoregulation is always occurring
- in the thermoneutral zone there is physiological thermoregulation -> vasodilation- increase heat disapation when its warmer, vasocontriction- when its cooler
58
Endotherms in the cold
- Increase their MR -> increases the heat production -> energetically costly
- thermogenesis- convert chemical energy into heat
- main sources of endogenous heat production: shivering and nonshivering thermogenesis
- change thermal conduction (regulated process):
- decreasing driving force- counter-current exchange mechanism in limbs and pulsatile blood flow to limbs
- decrease surface area- less heat loss (short ear, short limbs)
- increase size- smaller surface area/volume ratio
- increase insulation- fur
- avoidance- hibernation, torpor
59
brown fat
- adipose tissue (BAT)
- specialization for fat-fueled thermogenesis
- found in mammals usually in neck and between shoulders (core)
- adaptation for rapid, massive heat production- heats up very quickly
- highly vascularized- heat spreads to other parts of the body via the circulation
60
Shivering thermogenesis
- muscle contraction to produce heat
- groups of antagonistic muscles are activated- little net movement other than shivering
- muscle contraction is only 25% efficient- 75% energy expended is released as heat -> good! -muscles are highly vascularized and heats up the blood
- energetically costly bc it is inefficient
61
nonshivering thermogenesis
- metabolism of fat to produce heat- very little energy is conserved in the form of ATP
- brown fat
- heats up the core (thermoregulation)
62
MR versus size
- small animal- low whole animal MR, very high MR
- large animal- high whole animal MR, very low unit metabolic rate -> more cells and need more energy to do things
- larger animals retains the heat better per unit mass than smaller animal ->
- larger animals use less energy per unit mass to stay warm
63
huddling
- example of size principle
- decreases effective surface area reduced heat loss
- behavioral thermoregulation
- reducing SA/V ratio
64
Insulation
- piloerection- individual hairs stand up which allows the fur to capture more air -> increases insulation (goosebumps)
- fur/hair- traps air
- feathers- trapping of air (fluffing feathers)
- fat- increases insulation on the inside by generating fat- layer between blood and surface
- air is better strategy when possible
65
Effect on insulation of the endotherm curve
- thermoneutral zone is extended
| - less increase in MR needed to maintain body temp (less steep)
66
Avoidance
- hibernation- organism continues to thermoregulate but at a lower body temp -> curve shifts down and to the left -> thermoregulating at a colder ambient temp
- usually animals hibernating use insulation as well
- torpor- suspends thermoregulation and allows the body temp to get low bc it needs more energy that it has (hummingbird) -> can freeze
67
Moderate heat stress
- physiological/behavioral thermoregulation- facilitate heat transfer to external environment with little to no increase in metabolic rate
- body temp> ambient temp
- heat dissipation/conduction:
- vasodilation
- thermal windows- exposing skin
- change posture- increase SA
68
extreme heat stress
-body temp
69
heterotherms
- animals capable of varying degrees of endothermic heat production
- temporal heterotherms- body temp varies over time -> hibernation, torpor, body temp fluctuations during the fay (camels)
- regional heterotherms- different parts of body at different temperatures- ectotherms that can maintain core temperature higher than ambient temperature (tuna, large sharks), testes in some mammals (canines, humans)
70
Large fish regional heterothermy
- very large
- specialized circulatory system- counter current heat exchange between venules and arterioles maintains core temperature higher than ambient temp
- retains
- core has a lot of muscles
71
hypothalmus
- mammals thermostat
- Henry Barbour- implanted a small temperature controlled probe into different parts of the rabbit brain:
- evoked strong thermoresponses only when used to heat or cool the hypothalamus
- cooling-> metabolic rate and body temp increase
- heating -> panting and body temp decrease
- highly sensitive
- maintains core temp at the expense of extremedies
- hypothalamus integrates all of the temperature related information and orchestrates the systemic response
- temperature of hypothalamus most important
- integrator is in the preoptic/anterior hyporthalamus
- set point of 37C
- controls the ANS, higher brain centers, and pituitary gland
72
fever
- hypothalamus thermoregulatory center is very sensitive to pyrogens (fever producing substances)
- pyrogens raise the set point in the hypothalamic thermoregulatory center
- exogenous pyrogens- polysaccharides produced by gram negative bacteria
- endogenous pyrogens- heat-labile proteins produced by the animals own leukocytes, released in response to circulating exogenous pyrogens
- exogenous pyrogens raise body temperature both by:
- acting directly on hypothalamic thermoregulatory center (be increasing the set point) and
- indirectly by stimulating the release of endogenous pyrogens
73
In a cold animal, a large animal is more efficient at maintaining body temp than a small animal even though it has a higher MR
true
| -large animals have more cells, higher whole animal MR
74
In terms of regulation of body temp, boundary layers would most likely be problematic on a sunny, hot day with no wind
true
- without the wind the boundary layers with not be disrupted
- the layer close to the skin will be the same temp -> low driving force -> no heat exchange to the environment
75
in ectotherms, as ambient temp decreases, metabolic rate decreases which then causes a decrease in body temperature
false
- these statements are true but in the wrong order
- decrease in ambient temp causes a decrease in body temp thus causing a decrease in MR
76
Water and ion balance (osmolarity and body volume)
- all cells need to exist in an aqueous environment
- H2O and salts (ions)- need to keep relatively constant (homeostasis, budget)
- tightly associated with temp regulation- evaporative cooling critical to maintaining body temp under conditions of high ambient temp and/or high MR
77
body fluid (BF)
= ECF
78
distribution of fluids in the body
- most of the water is in the intracellular fluid compartment
- the volume of blood is 5 L (RBC's + plasma)- RBC's make up 40% of blood volume
79
concentration
of molecules of solute/volume or mass of solvent
80
sucrose
- does not dissociate
- nonpolar
- non salt
81
transport equation
dQs/dt alpha -Ds * (C2-C1)
- Ds: diffusion coefficient- describes how readily the solute moves function of solute (nature and molecular wt)
- (C2-C1): concentration gradient of solute- driving force of diffusion
82
diffusion
- random thermal motions (function of temperature)
- passive
- the movement of a substance from a region of high concentration to a region of low concentration
83
permeability
- something we can measure
| - changes over a function of time
84
membrane flux equation
- dQs/dt = P* (C2-C1)
- P: membrane permeability- defines how easily a substance can cross the membrane
- (C2-C1): driving force- concentration difference across membrane
85
hydrophobic solutes
diffuse through membranes
- nonpolar, saturated fatty acids
- can easily diffuse
86
hydrophilic solutes
diffuse through transmembrane channels (pores) in membranes
- charged, polar
- need proteins to cross
- transmembrane channels are highly regulated
- H2O
87
phospholipid bilayer
- a barrier to hydrophilic substances due to hydrophobic core
- hydrophobic tails (nonpolar, saturated fatty acids)
- hydrophilic head (charged, polar)
88
transmembrane integral protein
- a membrane protein that carried charged particles across the membrane
- span the entire membrane
- highly regulated (synthesis, expression, signally molecules)
- creates a pore/channel
89
aquaporin
- transmembrane protein specific to water
- passive always**
- osmosis
90
open state channel
conducting
91
closed state channel
non-conducting
92
passive transport
- requires concentration gradient (simple diffusion)
- requires some way for substance to cross membrane
- other factors can influence passive transport (electrical forces, ions, membrane potential)
93
sodium potassium pump
- not transmembrane
- brings Na outside the cell
- brings K into cell
- against concen gradient
- ATP
94
water balance
- no mechanism to actively transport H2O across membrane
- only mechanism for the movement of H2O is osmosis
- need to think in terms of movements of solutes (ions and non-electrolytes)
95
colligative property
- property of solutions whose magnitude depends only upon the solute concentration and the nature of the solvent, but is independent of the nature of the solute
1. osmosis
2. boiling pt elevation
3. freezing pt depression
4. vapor pressure elevation
96
concentration
number of moles per liter in a solution
97
concentration trend
as you increase solute concentration you decrease water concentration
98
osmotic pressure
- pressure that must be applied to oppose osmosis
| - hydrostatic pressure produced by osmosis
99
osmolarity
- an index of water concentration -> the higher the concentration of solutes, the lower the concentration of water
- each substance contribute equally and independently to the osmolarity
- Na is important to the osmolarity of the intercellular fluid
- K is important to the osmolarity of the intracellular fluid
- dealing with whole animal/organ level
- need to know frame of reference
100
qualitative feel
- the higher the concentration of solutes in a solution, the higher the osmolarity of the solution and the lower the concentration of H2O
- H2O will move from a region of low osmolarity to a region of high osmolarity
101
Osmolarity questions
- osmolarity of a solution of .1M NaCl + .1 M sucrose
- NaCl dissociates so -> 1.M Na + .1M Cl
- .1 +.1 +.1 =.3M
102
isoosmotic
- same osmolarity
| - no net movement of water
103
hypoosmotic
lower in osmolarity
104
hyperosmotic
higher in osmolarity
105
tonicity
- better for cellular level
- tonicity is defined as the effect a solution has on a cell
- property of the solution
106
Hypotonic solution
-cell swells
107
isotonic solution
H2O balance
108
hypertonic solution
cell shrivels
109
increasing the concentration gradient of an ion across the membrane increases the membrane permeability to that ion
false
| -transport equation
110
carrier protein
- escorts it through the membrane
- never creates a channel
- ex. uniport- facilitates the movement of a single molecule
- ex. symport- carries two molecules (glucose & sodium)
- ex. antiport- carries substrates in opposite directions (sodium potassium)
- can be passive or active
- can hydrolyze atp
111
active transport membranes
- not a transmembrane channel
- requires energy
- sodium potassium pump
- antiport
- requires some enzyme system
112
osmoregulator
- an animal that maintains a stable BFOC despite osmotic stress (mammals)
- can only be ionoregulator
113
osmoconformer
- an animal whose BFOC tracks environmental osmotic concentration
- hypoosmotic cant be osmoconformer
- can be either ionoconformer or ionoregulator
- advantages- conserves energy, wont lose or gain water (maintaining size)
114
euryhaline
-an animal that can survive over a wise range of environmental osmotic concentrations
115
stenohaline
-an animal that can tolerate only a limited range of environmental osmotic concentrations
116
ionoconformer
-distribution of solutes (ions) is similar to environment
117
ionoregulator
-maintaining a different distribution of solutes (ions) than the environment
118
osmoconformer, ionregulator
why is this advantageous?
- hemoeostasis
- different distribution is good for the cells
119
are all osmoregulators ionoregulators
yes!
120
water budget
- IN- passive, regulated
- OUT- passive regulated
- maintains a constant internal environment and volume IN = OUT
- goes hand and hand with ion concentration
121
water in
- drinking
- food (5%-95% water)
- metabolic water- aerobic
- uptake from body surface
122
water out
- urine
- feces
- evaporation
- > respiratory
123
BFOC
-body fluid osmotic concentration
124
water and ion regulation are linked because...
- osmolarity depends on the amount of ions and the volume of water
- movements of solutes typically leads to H2O movement
- water always moves passively but solutes can be moved in a way so that water can be moved down its gradient
125
factors to consider in terms of H2O/Ion balance
- affect passive gain/loss and maintain balance that needs to be dealt with using regulated gain/loss
- availability of H2O and salts
- respiration/temperature (terrestrial animal)
- permeability of integument (cutaneous evaporation)
- diet (affects salt uptake)
- excretion (regulated loss)
126
availability of H2O salts
- aquatic vs terrestrial animal
- seawater vs freshwater
- terrestrial: desert vs humid environment
127
respiration/temperature (terrestrial animal)
- respiration- passive H2O loss from respiratory surface
- higher temp- higher water content
- sweating/panting
- water is lost when we exhale
128
permeability of integument (cutaneous evaporation)
- frogs/amphibians- high permeable skins
- reptiles, desert amphibians, birds and most mammals- skin is highly impermeable to water
- ex. cow hide is so impermeable it can be used to carry liquid
129
excretion (regulated loss)
- all osmoregulators have some mechanism to excrete excess H2O/ions
- vertebrates-kidney- major organ of water/ionic balance
- many other species have additional organs or take advantage of other systems:
- salt glands in marine birds and reptiles
- gut and gills in fishes
- skin and bladder in amphibians
- malpighian tubules in insects
130
osmoregulator eating marine osmoconformers
- they are salty
- they must find a way to get rid of excess salt
- ex. seagulls
131
fresh water fish
- challenge: water is always gaining water and losing ions bc it is so hyperosmotic to its environment
- solution:
- does not drink water
- kidneys produce large amounts of diluted urine
- eat salty foods
- pump salts (Cl) from the water through specialized cells in gills (chloride cells) to the ECF- acid secreting cells (PNA-) import Na+ and base secreting cells (PNA+) import Cl
- chloride cell- transport chloride in for exchange with bicarbon
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salt water fish
- challenge: loses water through gills to environment and has too much salt bc they are so hypoosmotic
- solution:
- drinks a large amount of water
- absorbs ions actively into the interstitial space (ECF) to create a gradient for water to be absorbed passively across gut wall
- its urine is about the same osmolarity as body (not that sufficient)
- actively secretes chloride across gills through specialized cells (chloride cells) -> export Cl and Na follows passively, sodium potassium pump is present
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general functions of transport epithelia
- asymetrical distribution of transporters within the cell (basal vs apical membranes)
- epithelial cells are connected by tight junctions- form an impermeable sheet
- many type of epithelial cells
- abundant mitochondria to meet energy demands of ion transport
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transport epithelial cells
- specialized
- interface between the outside and inside of the body
- polarized
- apical- outside
- basal lateral- inside
- pumping substaces
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vectoral transport
-things move in a particular direction
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transcellular transport
- movement of solutes (or water) through epithelial cells
- highly regulated
- generally active
137
paracellular transport
- movement of solutes (or water) between adjacent cells
- small enough
- diffuse
- gradient
- passive
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coupling reactions
-basolateral membrane- primary active transport- contains the sodium potassium pump- maintains a low intracellular sodium concentration -> allows glucose to enter cell (at the apical surface) against its concentration gradient bc the sodium gradient made by the pump
apical membrane- cotransporter- secondary active transport even though it doesnt produce ATP bc its taking advantage of the sodium gradient being produced
-uniporter- facilitated diffusion- allows glucose to leave the cell on the basolateral surface
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channel protein
- creates a pore through the membrane
- can be open or closed (gated or not)
- gated channels open and close in response to signals
- always passive
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salt-exreting gland in birds
- they eat and drink things with a lot of salt so they need a mechanism to excrete it
- salt gland in seagulls
- circulatory system runs parallel to the salt gland tubules which has transport epithelium
- chloride from the blood transported to the interstitial fluid (some water is lost)
- counter current exchange
- blood is going up and salts are moving down
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why would it be more difficult for a small terrestrial mammal to be active during the day ans allow its body temp to fluctuate than a large terrestrial mammal such as a cammel
- small animal has a large surface area to volume ratio -> gains heat very quickly
- larger animal, per unit mass, gains heat a lot slower
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kangaroo rat
- gets all its water from metabolism (aerobic)
- needs to retain water
- behavioral strats- avoid heat so it doesnt undergo evaporative cooling -> active at night -> avoidance
- kidney is adapted to concentrate urine (not a lot of water loss)
- temporal counter current exchange to minimize respiratory H2O loss
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temporal counter current exchange
- inhales dry air
- as the air travels down the air become humidified by the airways
- when the air gets to the lungs there is low driving force for water loss to respiratory surface
- as we exhale the dry air ways absorb the water back up (dehumidify)
- all terrestrial animals
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camel
- thermocapacity is large -> due to its size and ratio
- body temperature rises slowly
- does not want to evaporative cool
- the less water is has access to the more it lets its body temp fluctuate ->avoidance
- avoids thermoregulation, specifically evaporative cooling* bc it can due to its large thermocapacity and small SA/V ratio
- drinks a lot of water when it can
- active during day and uses strats to minimize heat gain
- temporal counter current exchange
- doesnt try to make high concentrated urine- stores urea in tissue and doesnt need to urinate
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the metabolic rate of a hibernating is independent of ambient temperature
-false
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when salmon migrate from fresh water to salt water they generate new chloride cells in their gills that actively transport Cl out to the environment
true
- creates new chloride cells (different types)
- cellular composition changes
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Osmolarity of the average mammal
300 mOsm
