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enzymes - 2 principal roles
speed chemical reactions (as catalysts), often regulate reactions
how enzymes participate in teh regulation of cell function (2)
- 1. the types and amounts of enzymes synthesized by a cell determine the metabolic pathways that are functional in the cell
- 2. the catalytic activities of the enzymes that actually exist in a cell at any given time can be modulated to control the rates at which teh functional metabolic pathways operate
conformity vs. regulation
- conformity: internal property of the animal changes when teh environment changes (less energy required)
- regulation: internal property of the animal is held constant despite changes in teh environment --> homeostasis (allows you to move from environment to environment though without being bothered)
The five time frames that physiology changes
- acute (immediate - first minutes/hour after affected)
- chronic (expressed following prolonged exposure to new environmental conditions) (acclimation vs. acclimatization)
- evolutionary changes: involving changes of genotypes (a population rather than individual change)
- Developmental changes: different genes are internally programmed to be expressed at different stages of development
- Periodic/clock-controlled changes in animal's phenotype: teh internal capability to keep track of the passage of time - internally programmed, repeating cycles in their physiological states
acclimation vs acclimatization
- acclimation: responses to changes in one environmental variable (lab usually)
- acclimatization: response to new natural environment where several differences might arise simultaneously
- both are types of phenotypic plasticity (ability of an animal to express two or more genetically controlled phenotypes)
why a trait could exist other than being adaptive?
- pleiotropy - control by an allele of a single gene of two or more distinct and seemingly unrelated traits
- genetic drift - gene frequencies shift in chance directions (random mutation or dominance in isolated population)
- could have been effective in the past and there is not enough pressure to get rid of it
- principle constituents of the matrix in which proteins are embedded in cell membranes and intracellular membranes
- can be fluid or not
- vary among animals (number of unsaturated vs saturated will differ in animals living in different temps -- more cold = more unsaturated?)
isozymes in animals
- the different forms of enzymes in different animals - many forms of different enzymes that contribute to animal's adaptiveness (like LDH)
- variations in: affinity for substrate/affinity for allosteric regulators/turnover number/ph and temp dependence/stability
isozymes vs. interspecific enzyme homologs
- isozymes - different molecular forms of an enzyme produced by a single species
- interspecific enzyme homologs - different molecular forms of an enzyme coded by homologous gene loci in different species
- modulation of the catalytic properties of an enzyme by the binding of nonsubstrate ligands to specific nonsubstrate-binding sites (can be inhibiting or activating)
- principal way in which cell function is regulated
phosphofructokinase allosteric enzyme regulation
citrate - when lots of O2, citrate increases, downregulation
AMP - when AMP high (ATP is low), upregulation
- major class of cells in the body - critical to body function
- acts as a barrier from inside (basal) to outside (apical)
- responsible for transport, secretion of hormones, barrier function
- because the apical and basal surfaces have different channels/pumps --> specialized for secretion or absorption
- separate the apical and basal membranes
- surrounds the epithelia
junction at which mutually adhering glycoprotein filaments from two adjacent cells intermingle
open pores between the cells
primary vs secondary active transport vs. facilitated diffusion
- primary: ATP is used directly, the energy comes from teh breakage of the high energy phosphate bond
- secondary: energy comes from a gradient that was created by a primary active transport
- faciliatated: type of passive transport that is dependent on single transport carrier proteins
examples of cnidaria/ctenophora/lophotrochozoans/ecdysozoans/deuterostomes
- cnidaria: jellyfish
- ctenophora: comb jellies
- lophotrochozoans: worms? roundworms? mollusca - squids
- ecdysozoans: insects - arthropoda
- deuterostomes: like us, chordates
- first to have complete digestive system
- radial symmetry
- ciliated combs for propulsion
- only 2 cellular layers (ectoderm and endoderm)
protostomes vs. deuterostomes
- defined by what happens to teh blastopore
- the development origin of the coelem also differs
- protostomes: first opening in the body is the mouth
- deuterostomes: second opening is the mouth, first is the anus
- both have a complete gut!
coelom and the mesoderm (and the different types)
- acoelomate - no space at all - not a coelomate (like a flatworm)
- pseudocoelomate - a fake coelomate (no layer for the internal part) - like roundworms
- coelomate - the red mesoderm leaves space for a complete compartment (fluid filled space)
whats the advantage of being a coelomate?
motor control of the internal organs are independent of the body wall - independent control of digestion
acoelomate protostome phyla importance
- first excretory system that is spearate from other organs in teh body
- real organs appear
- begin to see complexity/specialization
- multiorgan digestive system
are all deuterostomes coelmate?
sum of the processes by which animals acquire energy, channel energy into useful functions, and dissipate energy from their bodies
what are substrates for energy and anabolic processes?
carbohydrates, lipids, proteins
what is the energy gotten from catabolism used for in the body?
- anabolism (to make RNA, DNA, proteins, glycogenesis)
- transport (maintenance)
- motor activity
fed vs. fasting states
- fed (absorptive) - taking in/processing substrate
- fasting (post-absorptive) - when animal is using primarily stored substrate
efficiency of catabolic/anabolic processes
- all are inefficient! heat is realeased!
- metabolic rate is calculated by how much energy is there at the start (not how much you actually use, just the amount of energy in the bonds of hte food you eat!)
- total daily energy expenditure
- (basal metabolic rate + activity + SDA)
- the metabolic rate per day!
Basal metabolic rate vs Standard Metabolic Rate
Basal Metabolic Rate: applies to homeotherms only, whatever you need for lying down, sleeping, fasting, and in thermoneutral zones (range of temps within which the metabolic rate is minimal)
Standard Metabolic Rate : applies to poikilotherms (ectotherms), while it is fasting and resting
- specific dynamic action - the amount of energy you use to digest your food
- increase in metabolic rate because of food ingestion
- roughly proportional to the amount of food eaten
also called TEF - thermoeffect of food
metabolic rate and oxygen consumption
- kcal/day and O2 consumption are related
- oxidative metabolism uses up oxygen as well as substrate so metabolism an also be given in L O2/time
efficiency of metabolism?
- roughly 40% for oxidative metabolism
- Energy captured in ATP/Energy available from glucose
- BUT the overall efficiency of actually moving, producing work, i slower than 40% because of heat loss
- diet-induced thermogenesis - also included in SDA (TEF)
- food stimulated increase in metabolic rate unrelated to actual digestion and storage
- long-term increase in metabolic rate induced by persistent overeating is dubbed DIT
- glucose storage is limited, but it is very important!
- we can make glucose by gluconeogenesis (amino acids, lactate, glycerol, NOT FATTY ACIDS)
- some tissues do it all the time not just when we have a shortage of glucose
how do you use fats then for energy and stuff?
- must go through acetyl coA and oxidation
- break them down by turning it back to acetyl coA
- excess fat breakdown leads to ketones that the brain can use in severe fasting
- must be broken down first into amino acids (requires deamination, y getting rid of NH3)
- no protein is stored for later purposes of energy - so excess protein is used immediately
- net catabolism of stored protein = starvation
gluconeogenesis only takes place where?
can you convert fatty acids to glucose?
the incorrect hypothesis to why their is an allometric relationship between weight and metabolic rate (i.e. why metabolic rate doesn't double with weight doubling)
- the idea that all animals want the same body temperature --> so heat production must equal heat loss
- heat loss is proportional to surface area (as you double weight you don't double surface area so MR won't double)
- MR is proportional to SA not weight!
bigger animals have a lower/higher specific metabolic rate? and allometric equation for it!
- MR = a W ^.7
- MR/kg = a W^-.3
- a tends to change from animal to animal - shifts the curve up or down
- a is the y-intercept - changes the curve up or donw
- b is the slope on the log log graph --> refers to the curvature
how is constant Tb hypothesis for allometric MR relationship proven wrong?
plants show this same type of allometric relationship but they don't regulate their temperatures!
Vo2max can often be __x as high as BMR
how much fat you use for energy depends on intensity - more intense = equal use more/less fats?
more intense --> use less fats as energy
but we tend to balance substrate use over time
the more fit the person - the more they are able to use fats instead of carbs as energy
oxygen deficit and how we make up for it
- the time at the very beginning of your workout when your actual O2 uptake from teh environment does not match the needed ATP
- make up for it through anaerobic glycolysis (lactic acid production), high energy phoshagens, and use of O2 stores (myoglobin) in muscle
how do you get to the pay as you go phase for exercise?
increased ventilation, more oxygen blood flow
pay back phase
- even tho you went through pay as you go, there is still the oxygen deficit that caused you to have lactic acid around
- at the end of your exercise you have an excess of oxygen consumption
- pyruvate must metabolize lactic acid
- must refuel phosphagen sotres
- put O2 back into the myoglobin
some people are better at glycolytic metabolism and othesr are better at oxidative
- differences in muscle types
- dark = more myogloin - more oxidative capable muscles - longer stuff
- white - more glycolytic muscle, better for sprinting, b/c can gear up a lot faster
so is it genetic differences or training differences in the differences between sprint and distance muscle?
- mostly genetic
- training increases capacity of existing muscle
is oxygen or substrate usually teh limiting factor in exercise?
responses to low environental oxygen
- regulate to keep O2 normal
- short term: increase heart rate, dilate blood vessels
- longer: more red blood cells, larger lungs
- or reduce metabolism to match available oxygen (metabolic depression)
- turn down rates of active pumping and ionic currents
perform anaerobic ATP production instead (lactate, ethanol, or produce another end product like acetic acid, other acids)
- teh sequence of reactions that converts glucose to lactic acid
- requires LDH (the substance that reduces the pyruvic acid)
- doesn't release much ATP because lactic acid itself is an energy rich molecule (the reduction to it doens't release much) (this is why we do not get rid of lactate b/c it is such a high energy compound)
metabolism of lactic acid
- requires O2 (must be converted back to pyruvic acid first)
- it can then be converted to glucose (gluconeogensis)
- or it can be fully oxidized by Krebs and electron transport chain
- temporary sotres of high energy phosphate bonds
- provide an additional way to make ATP without O2
- occur in muscles, like creatine phosphtae
internal stores of O2 can also be used to make ATP
- preexisting O2 stores in a cell or tissue
- muscle cells have more O2 storage capacity because of their myoglobin!
slow oxidative fibers vs. fast glycolytic fibers
- SO - oxidative, make ATP by aerobic catabolism
- FG - glycolytic, make ATP anaerobically
- they differ in how they can take up and store O2 (SO - lots of myoglobin, so O2 used easily and stored well)
- hypoxia: low level of O2 in tissues
- anoxia: absence of O2 in tissues
cost of transport
energy cost per unit of distance traveled
endotherms vs ectotherms
- endotherms - burn enough food so that internal heat gnereation keeps Hs high (heat stored in body) - very good regulators (keep Tb relatively constant --> homeotherms)
- ectotherms - expend little energy and rely on environmental heat sources for Hs
equation for body temp
- Tb = Hs/(M*C)
- Hs = heat stored in teh body
- M = mass
- C = heat capacity (usually 0.7 for most animals)
keep Tb constant - Hs is large (endothermu) and change in Hs is zero (homeothermy)
Tb varies, ectotherms (variable temps)
what determines stored heat?
Hs = Hm - Hcond - Hconv - Hr - He
- Hm = metabolic heat generation
- Hcond = conductive heat gain or loss
- Hconv = convective heat gain/loss
- Hr = radiative heat gain/loss
- He = evaporative heat loss (never a gain)
radiation heat transfer
- does not require direct contact
- we radiate temeprature in both directions - what really matters is the net which depends on the temperature difference (between temp of animals surface and temp of object, not Ta)
- we lose a lot of heat by radiation
- does not depend on temp difference directly
- depends on the amount of water that evaporates from your surface (which depends on vapor pressure of water on skin and in world)
- vapor pressure changes with temperature
- metabolic heat production
- metabolic rate = metabolic heat production + external energy
thermal neutral zone (TNZ)
- where Hm and Tb are constant, outside the TNZ Tb only remains constant if Hm increases
- if hotter - Hm goes up because it takes energy to sweat, etc.
- if colder -Hm goes up to be warmer
how do we increase our metabolic rate when the ambient temp is below our lower critical temp?
non-shivering thermogenesis and shivering thermogenesis
endocrine stimulation of metabolism, brown fat (adipose tissue, generates heat but not ATP_
- somatic muscle contraction, not autonomic
- generates heat but not work
difference in thermal relations from ont time to another, from one body region to another (temporal or regional)
- transfer of heat through a material substance that is macroscopically motionaless (by atomic-molecular interactions)
- rate increases as temp difference increases
- rate decreases as thickness increases
- transfer of heat rhougha material substance by macroscopic motion of the substance (fluid flow needed)
- faster than conduction
- rate depends on temp difference between surface of object and the fluid
eurythermal vs. stenothermal pokilothermy
- eurythermal - can function over a wide range of body temps
- stenothermal - have narrow ranges of body temp over which they can function
how do animals cope with freezing conditions?
- production of antifreeze compounds (increase concentration of solutes or antifreezes that prevent water from joining any crystals that start to form)
- tolerance of freezing
how insulation is modulated
- pelage or plumage (hairs/feathers)
- vasomotor responses (altar rate of blood flow to skin surfaces)
- postural responses - altar amoutn of body surface area exposed to ambient temp
allows body temp to fall close to ambient temp during winter
like hibernation but in the summer
allows body temp to fall to ambient temp for only part of each day
controlled hypothermia methods
- hibernation, estvation, daily torpor,
- allows teh escape of energy demands of homeothermy!
temperature is controlled by which brain region?
teh hypothalamus! it keeps track of actual and desired temperature (mostly sympathetic system control)
knows this by temperature sensors all over your body to determine what your actual temp is
equation for conduction
Hc = (Kc/L) (Tb-Ta)
- where Kc is conductive heat transfer coefficient
- and L is the thickness of insulating layer between Tb and Ta
physiological temp regulation if too warm
vasodilation (increase blood flow) in skin --> reduces L, increases Ts , which causes Hc and Hr to increase (to lose heat!!)
physiological temp regulation if too cold
- vasoconstriction (blood out of the layer by the skin, decrease the skin temperature, and increases L, so then Hc and Hr decrease) (try to keep heat)
- cool expired air
- a physiological response to being too cold
- make hair stand up! makes fur thickness larger = more insulation = larger L so Hc is smaller
the increase in metabolic heat production when ambient temp is below lower critical limit
countercurrent heat exchange
allows for selective restriction of heat flow to the appendages
if close to each other - can promote heat conservation (transfer of heat rom arterial blood to venous blood rather than heat loss from the blood
two sets of arteries --> so countercurrent heat can be activated or deactivated
people don't have this!
countercurrent exhange importance in the cold (not just the usual for heat)
running animals - dont want the brain to cook if its too warm!
venous blood goes around by the nose --> cooled by evaporation, and then goes by the arterial blood to the brain and cools it!
a cold nose is important to cool teh blood to the brain, but what else does it do?
- minimizes evaporation
- a lowered temp lowers the vapor pressure - less water evaporates - less heat is lost
compensation in thermal relations for poikilotherms
after a physiological rate has been raised/lowered by an abrupt change in body temp, any subsequent, long-term tendency for the rate to return to its original elvel even though the new temp continues
2 reasons that temperature and heat are important for animal tissues
- affect rates of tissue processs (metabolic rates, rates of biochem reactions, rates of biophysical processes)
- affect molecular confirmations --> the functional states of molecules --> specialized for certain temps (molecular adaptation)
maintenance of a relatively constant membrane fluidity regardless of tissue temperature
in hibernation - do they turn of thermoregulation or turn of metabolism?
they probably turn off their metabolism but keep track of where their temp is (they can't really stop regulating their temp)
what type of hibernation to bears do?
- shallow hypothermia, winter sleep, carnivorean lethargy
- body temp drops but not close to ambient (just a few degrees colder)
why does an animals metabolic rate remain constant at all temps in the thermo neutral zone?
the animal is able to modulate its insulation
brown adipose tissue
brown fat - sites of Non shivering thermogenesis in placental mammals - receive rich supply of blood vessels and are well innervated by teh sympathetic nervous system, lots of mitochondira - capable of high rate of heat production
- metabolic rate goes down a ton! especially for small animals (don't have to turn on shivering or non-shivering thermogenesis)
- as you get to larger weights, the advantages of hibernating decrease (/c small animals have high specific metabolic rates)
how can an animal allow its body temp to go below freezing but not freeze? - really deep hibernation
- supercooling (prevent ice crystals) - not really very important, mammals don't have this ability
- freezing point depression - any solute in teh water will lower the freezing point (the osmaolarity of body fluids allows the body temp to go a little lower than freezing point)
- the process of rewarming the body by metabolic heat production
- they do this to be able to sleep
- if they slept at low temps - parts of their brain would turn off and not be able to rewarm
role of stomach in digestion
largely storage (make sure that stuff doesn't get into the intestine too quickly), some protein digestion, chyme
role of midgut in digestion (and the three parts roles)
- small intestive - digestion and absorption
- duodenum - food
- jejunum - food, water, salts
- ileum - water, salts
role of hindgut in digestion
- the colon
- absorption of water, storage of feces
what are the accessory glands/what is their role in digestion?
- liver and pancreas
- enzyme and fluid secretion
which neurotransmiter for sympathetic and whih for parasympathetic?
and which gets signals from vagus nerve?
- sympathetic - norepinephrine
- parasympathetic - acetylcholine
- parasympathetic gets signals from the vagus nerve!
what are the 3 main layers to the gut wall
- mucous membrane - has the enterocytes (epithelial cell in intestine)
- submucosa - structural, and has some glands, where blood vessels are
- muscular layer
what are the two parts to the muscular layer of the gut?
- circular - lumen gets smaller when contracts
- longitudinal - contracts lengthwise
enteric nervous system
- in teh wall of the gut, controls the muscles of the gut
- sensory and motor cells in it
- can work independently but also controlled by autonomic nervous system (parasymp increases activity, symp decreases activity)
motility part of digestion
- keeps food going in one direction
- achieves this with sphincters - can't have it move continuously downward
- all except anal are under autonomic system (symp constricts, para dilates - relaxes)
- peristalsis and segmentation
peristalsis vs segmentation motility
- peristalsis - circular muscle squeezes behind, longitudinal in front - coordinated movements to get food to move in one direction - in esophagus and small intestine
- segmentation - mixes the food, uses circular motion, in colon
- both are controlled by enteric nervous system but with can be increased with parasymp stimulation and decresased with symp stimulation
why do we secrete so much water into the stomach/top of small intestine?
to make things wet enough to mix things - also puts in fluids that have acids/bases, enzymes
secretions of the salivary glands and pancreas
- similar - tissue surrounds gland made up of epithelial cells (acini projections)
- the blood flow around teh acini --> primary secretions of the filtrates of plasma (enzymes, fluids, salts)
- but then adjustments of the filtrates is made (saliva is neutral but hypoosmotic (adjustments to altar composition to .5 blood concentration) (pancreatic must secrete HCO3 and absorb Cl- --> very basic for buffer in stomach)
zymogen granules in acinus
- in the pancreas and salivary glands - look like little black dots
- contain the enzymes the pancreas is going to secrete
gastric gland secretion
- parietal cells - secrete acids
- chief - secrete pepsinogen (turned to pepsin in presence of acid)
- neck cells - secrete mucus, bicarbonate for buffering
what does the liver secrete
- mainly bile (is an emulsifier to digest fats)
- two input: hepatic portal vein from intestine and hepatic artery from aorta (the first in the path for anything absorbed in small and large intestine)
- one output - hepatic vein to vena cava
- also secretes plasma proteins and lipoproteins?
- gluconeogenesis and ketogenesis?
- immune functions
- storage of metabolic substrates
duodenum's role in digestion and absorption
- big role!
- bile and pancreatic fluid enter duodenum (From pancreas and liver)
- most absorption begins here, continues in jejunum, less in ileum
whats special about the small intestine gut wall that permits it to absorb?
has villi - on which tehre are enterocytes - which have microvilli --> very large surface area!
- there are specific enzymes that break down bonds in polysaccharides (glucose-glucose bonds)
- amylase is from teh salivary gland or pancreas - the rest are from teh small intestine (enterocytes themselves make them)
only 3 monosaccharides to absorb (glucose, galactose, fructose)
use teh same carrier at teh apical membrane - powered from teh Na gradient (cotransported with Na) (active transport)
goes across teh basal membrane by facilitated diffusion --> then goes into the villus and then enteres the blood
this facilitated diffusion is powered by the sodium potassium pump
levels in the cell are very small so it moves across the basal membrane with facilitated diffusion
then also across the apical membrane by facilitated diffusion as well
- requires many enzymes!
- pepsin, trypsin, chymotrypsin, carboxypeptidase
- most enzymes have a pH optimum near 7
amino acid absorption
- not like carbs in that di and tripeptides can be transported
- some intact proteins can be transported by endocytosis
a similarity to sugar transport - active with Na and then faciliated
other channels coupled with H+ to take in the di and tri amino acids - and then goes through facilitated
the substrate that the brain/heart prefers
- brain - glucose or ketone bodies
- heart - fatty acids
how is fat absorbed?
- the bile acids emulsify the fats (do this by being amphipathic). Along with pancreatic enzymes (lipase) breaks down the fats. These are freely absorbed into the enterocytes.
- Then in the enterocyte they combine with proteins to make lipoproteins called chylomicron
- This chylomicron then is released on the basal side --> too big for blood vessel so goes into lacteal
the composition of bile salts and where made/stored/released
- modified cholesterol (so more hydrophilic) plus a modified amino acid = amphipathic
- made in liver
- stored in gall bladder
- released into small intestine
control of the exocrine secretions - what controls the pancreas, saliva, and stomach secretions?
- there is neural but also endocrine control (hormones)
- saliva - mostly neural
- stomach - half neural half endocrine control
- pancreas - mostly endocrine control
Gastrin - what causes it to be produced, where produced, what are its effects. how is it regulated?
- Parasympathetic activity + lots of amino acids = G cells in stomach to release Gastrin
- Lots of gastrin acts on Chief/parietal cells (secretes pepsinogen and acid)
- THe high pH from the acid causes negative feedback for gastrin to stop being released.
Secretin - what causes it to be released, where released from, what it acts on, how regulated
- low pH in the duodenum causes it to be released from endocrine cells in the duodenum
- acts on the pancreas to secrete high bicarbonate fluid
- this causes the pH of the duodenum to go up. too high of a pH causes negative feedback to secretin
it also stimulates bile production in the liver!
CCK - what causes it to be produced, where it is produced, what it acts on/what it effects, how it is regulated
- fats in the duodenum cause endocrine cells in duodenum to release CCK
- acts on the pancreas to secrete enzymes and acts on the gall bladder to constrict (release bile into duodenum)
- once fats are digested and absorbed, CCK is stopped
hormonal effect on gastric emptying
- GIP, and CCK act on the pyloric sphincter
- if there is too much food the sphincter will close b/c it cannot have all that food there!
3 types of microbes
photosynthetic, chemosynthetic, and heterotrophs (fermenters - b/c no O2)
- Ruminant animals!
- Is before the small intestine (before the stomach too)
- Breaks down the cellulose to SCFA - energy for the cow
- also makes AA from urea and NH3
- the microbes themselves get absorbed - source of AA
- like rabbits, rhinos, zebras, apes, elephants, horses
- have cecum after the small intestine --> this is a problem b/c they don't get the essential nutrients (get SCFA's tho) like the Amino Acids
- they eat their feces!
are there animals that are midgut fermenters?
- yes - but its hard to have it in your small intestine because there are so many enzymes there
- some fish can do this though!
are insects deuterostomes or protostomes?
which are protostomes and which are deuterostomes? For mollusca, arthropoda, chordata?
- mollusca and arthropoda = protostomes
- chordata = deuterostomes
protostomes vs. deuterostomes. whats the difference in how the coelom originated!
- protostomes: originates from split of mesoderm
- deuterostomes: originates from outpouching of gut
- last three are chordatas
which chordate had the first notochord? and what is a notochord
- the urochordatas!
- notochord = flexible rod to support dorsal nerve cord
what things to conductive/convective/radiative/evaporative heat depend on?
- conductive: depends on insulation, body temp and ambient temp
- convective: depends on surface temperature and fluidity flow like wind speed
- radiative: temp of surface and temp of object (depends on difference in temperature)
- evaporation: depends on water vapor pressure