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152 Cards in this Set

  • Front
  • Back
When did the universe begin?
13.7 Billion Years ago
When did the solar system form?
4.6 billion years ago
When did earth develop a solid crust?
4 billion years ago
The history of the earth can be divided into how many stages?
What are the 6 stages of the history of the earth?
What is characteristic of the Hadean Era?
4.6-4 BYA
Prior to the formation of a solid crust
What happened in the Archean Era?
4-2 BYA
Orgin of life.
Single celled bacteria
No Oxygen
What happened in the Proterozoic Era?
2BYA - 550MYA
What happened in the Paleozoic Era?
550 - 250 MYA
Plants and Animals
What happened in the Mesozoic Era?
Appearance of mammals
Dominated by dinos
What Era are we currently in?
The Cenozoic Era
What is Characteristic of the Cenozoic Era?
Land is dominated by mammals and flowering plants. 65MYA to present.
What marked that start of the Cenozic Era?
The disappearance of the Dinos.
What is Panspermia?
Theory that life did not originate on earth but rather drifted here through space.
What are the requirements of life?
1) Way to harness energy
2) Way of storing and reproducing energy
3) Way to keep inside separate from the outside.
What are the two main views on how life originated?
1) Genetic View - Template replicators came first
2) Metabolic View - First organisms were metabolic systems
What is the main idea behind the Genetic View?
RNA can store information and it can act as an enzyme. Perhaps there was a stage in the development of life with nothing but self replicating RNA molecules
What is the main idea behind the Metabolic View?
Naturall occuring iron sulfide (pyrite) crystals which can catalyze oxidation-reduction reactions and polymerization of amino acids.
What were the environmental conditions of young earth?
No Free Oxygen
Free Hydrogen and saturated hydrides
Energy; electric discharge and soalr
Much hotter
What was the Oparin-Haldane Hypothesis?
Oparin: organic molecules undergo a series of reactions leading to more and more complex molecules.
Haldane: Primordial Soup
What was the Miller-Urey Experiment?
Early atm conditions heated and sparked.
What were the main results of the Miller -Urey Experiment?
After 1 week 15 amino acids were found in the mixture.
Also: ethanoic acid, lactic acid, and urea.
Later: similar experiments with CO2 and produced nucleotides.
Synthesis of organic rom inorganic!
Explain the relationship between polynucleotides and polypeptides?
Polynucleotides are very good at storing and transmitting information but lacked the ability to carry out cell functions. Polypeptides are better at complex cell functions.
What is the endosymbiotic hyppthesis?
mitochondria were once free living bacteria that developed an intra cellular symbiosis with a primative eukaryote.
What happened near the end of the Proterozoic Era? Effects?
Massive Ice Age. Everything was frozen for several years. Caused a mass extinction which killed off most edicarian forma and lead to the cambrian explosion.
How did the ice age end?
The greenhouse effect. CO2 from valcanos built up trapping suns warmth and eventually raising the temperature.
What is the Cambrian Explosion?
About 550 MYA there was a sudden appearance of fossils.
What was the Permian Extinction?
Largest mass extinction event in the earths history. 95% die out.
How did the Dinosaurs become extinct?
Large collion with earth. Proposed by Alvarez and his son. Very controvercial. But a iridium rich layer has been found everywhere on earth. Also there is the chixulub crater, 100miles wide.
What are the major findings of the Cenozoic Era?
65 MYA to Present
Modern Humans branched off from neanderthals 200-400 years ago in africa.
What are the two approaches to thermoregulation?
Thermal Conformity and Thermoregulation.
What is thermal conformity?
Allowing ones body temperature to fluctuate with the environmental temperature.
What is thermoregulation or homeothermy?
Maintain body temperature at relatively constant levels largely independent of mean environmental temperature.
Ware are some of the neural responses for thermoregulation?
Modification of blood flow to the skin, sweating, panting, shivering.
What are the long term acclimatization responses for thermoregulation?
Changes in insulation, increased capacity for metabolic heat generation.
What are the main problems associated with Low temperatures?
Thermal inactivation of enzymes
Inadequate oxygen to meet metabolic demands
Membrane structure alterations.
What changes occur in the membrane phospholipids to better acclimitize for the cold?
Decreased saturation with fatty acids
What is Ectothermy?
Obtain body heat from the external environment.
Adaptations to cold fall in two main categories..
Freeze avoidance
Freeze tolerance
What happens when water freezes?
drastic reduction in gas diffusion.
What happens when cells freeze?
Disruption of the cellular membrances.
Osmotic dehydration due to freezing of extracellular water.
What is the theoretical limit for freeze avoidance?
What is supercooling?
Removal of all crystalizing agents from the extracellular space. Water does not usually freeze at 0, can occur spontaneously, but can also remain liquid.
Water can supercool to -20 or lower in absense of nucleating agents.
What are colligative antifreezes? What do they do?
Sugar, Polyols (glycerol, trehalose.
More stuff = lower freeze point.
1moll= -1.86c
What are non-colligative antifreezes? What do they do?
Antifreeze proteins and glycoproteins. This will be an active process. proteins must directly interfere with crystalization. Smaller amounts are required.
What are Cryoprotectants?
Substances that help animals avoid damage from freexing of body tissue (Glycerol)
What are ice-nuclearing agents and how do they work?
they are substances that promote ice crystal formation in the extracellular fluid. Draws water out of the cells, increases intracelular concentration and decreases intracellular freezing point.
Dictates where the ice can form
What is the Wood Frog? Interesting facts?
Rana Sylvatica
70% of body water converted into ice when frozen
can survive frozen for over 4 weeks.
How does the wood frog tolerate freezing?
Blood Glucose rises 5 to 200-400nM
Glucose is triggered by ice formation
Suppress metabolic rate
What is counter current heat exchange?
Placemetn of the arteries and veins in parallel to facilitate heat exchange. Less heat is lost to outside and less energy is needed to re heat the blood.
What is regional homeothermy?
Exposed body parts are often allowed to cool more than core temperatures. Energy and heat conservation.
What role does the hypothalamus play in temperature regulation?
It is the site of the Set point to which the body temperature is controlled and regulated.
How does the bodies response to heat differ to that of cold?
Responses to cold are generated before there is a decrease in body temperature where responses to heat occur slightly after there is an increase in body temperature.
Peripheral thermoreceptors are primarily concerned with what?
Cold. We have many more cold receptors then warm ones.
What are two physiological adaptations that suggest we are better cold adapted?
1) more peripheral cold receptors
2) response to cold occurs before there is actually a drop in core body temperature.
How do thermoreceptors sense a change in temperature?
1. temp change stimulates a change in the metabolic rate of the receptor
2. cold decreases the activity, warm increases it.
this change in enzyme activity is reflected in the discharge rate of the thermoreceptor afferent neurons
If the peripheral cold receptors sense cold, relay it to the hypothalamus, what happens next?
1. Shivering via activation of the skeletal muscles
2. Increase sympa NS output will decrease peripheral blood flow.
3. Increase BMR through NST
How is BMR increased in response to cold?
Increased levels of thyroid hormone and epinephrine increase the BMR x5. THis is know as Non shivering thermogenesis.
What happens to cardiac output in the cold?
It will be elevated, increases heart rate.
Why does the heart have to work harder in the cold?
Increase in total peripheral resistance, increase in afterload.
What metabolic changes take place in the cold?
T3 stimulates andrenergic receptors thereby potentiating the effects of the SNS release of NE
What is the Hunting Reflex?
reflex designed to prevent damage to the peripheral tissue. Transient dilations in blood vessels send warm blood to restricted areas. This can be conditioned to occur earlier and stronger.
What happend in Hibernation?
Decrease in body temerature
Reduced heart rate
apnoic breating
Long periods of torpor
What happens to the turn over of ATP during hibernation?
Decreases to 5% of normal
What are some of the differences between brown and white fat?
Brown has more mitochrondia.
Brown has lots of little fat dropplets where as white is one big one.
Where is Brown Adipose tissue derived from?
Muscle cells
What is the difference between Bruscle and Birte?
Bruscle is brown adipose cell, having derived from muscle. Brite is a phenotype of a white adipose cell that will have multiple fat droplets but still mostly function as a white adipose cell
What happens to NST with initial and prolonged exposure?
Initially shivering > NST
Prolonged NST > Shivering
Why might brown adipose tissue have increased vascularization?
Due to its high metabolic rate, need for oxygen.
Why is having multiple little fat droplets an advantage?
Greater surface area allow the BAT to mobilize its fuel source quicker.
Where do we find an abundance of BAT?
Small animals, Cold adapted mammals, hibernators, newborns.
Why do small animals have so much BAT?
They have a large surface area to volume ratio.
What is the first step in how BAT creates heat?
CNS stimulates sympathetic nerve endings in BAT to release nor-epinephrine
How does bat make heat?
After NE. NE will bind to the beta3 adrenergic receptors to make cAMP and activate Protein Kinase A. PKA activated hormone sensitive lipase to breakdown TG into FFA. FFA binds to uncoupling protein 1 to allow the mitochrondria to produce heat.
What are the two hypothesis on how UCP1 makes heat?
Fatty acid cycling hypothesis - UCP1 flips FA ions from the matrix to the intermembrane space where they acquire a proton and flip back to release it in the matrix.
Proton Buffering Model - FAs bind to the side of UCP1 to act as a bridge allowing protons to bypass ATP which blocks the channel
What happens if UCP1 is blocked out in mice?
They will have no capacity to increase oxygen consumption in response to NE
How/Where does BAT exist in humans
Newborns will have it in the thorax
BAT will decline at 6 months
Adults will have it in the subclavical, aorta, spine, kidneys approx 60-80g
How much of the metabolic rate doea BAT account for?
Do men or women have more BAT?
How does obesity effect BAT?
obesity is associated with a decrease in the level of BAT.
What are the genetic polymorphisms associated with BAT?
polymorphism in UCP1 is associated with weight gain, reistance to weight loss, susceptability to obesity, anddecreased expression of UCP1.
25% of people have this
What are the current drugs being tested to activate BAT?
TZD which enduces UCP1 expression
Ephedrine - sympathomimetic
Beta 3 agonists
thyroid hormone mimic - not so bad.
To what degree can the body maintain a water balance?
What are the main functions of fluid in the body?
Stabilize temperature, carry nutrients to and from
What are some of the early signs of dehydration?
Fatigue, loss of appetite, flushed skin, heat intolerance, light headed, dark urine
What are some of the late signs of dehydration?
Difficulty swallowing, clumsiness, delirium, shrivelled skin, sunken eyes, numb skin, muscle spasms, painful urination.
How is dehydration measured?
1lb loss = 450mL
1kg = 1L
What will occur with a 2% water loss of BW?
Impaired thermoregulatory ability
What will occur with a 3% water loss of BW?
Reduced muscular endurance.
What will occur with a 4-6% water loss of BW?
reduced strength, endurance, heat cramps
What will occur with a >6% water loss of BW?
Severe heat cramps, heat exhaustion, heat stroke, coma, death.
What will dehydration do to blood volume?
Cause a decrease in plasma volume. this will reduce stroke volume and therefore cardiac output. Must increase HR to maintain CO
What happens to peipheral blood when dehydrated? and Increased core temp?
it will actually decrease.
Where in the body does most of the water loss occur?
In the cells. causes cell stress and seriously effects signalling
How long does sweat take to acclimatize?
2 weeks
How does the sweat of trained vs untained people compare?
trained people sweat more but they dont lose as much solute.
What are the general hydration guidelines?
240-720mL before exercise by 1 hour
120-240 immediatly prior
120-240 every 15 min + 6-g CHO during
450mL for every lB lost
What suggests that thermophiles might actially be one of the first organisms?
Carls Woese's tree.
thermophiles are at the base of the tree thus perhaps arrived first.
What are some of the typical thermophile habitats?
Desert, compost, deep biosphere, geothermal systems
At what temperature does photosynthesis stop?
75 deg c
What are the main fuel sources of thermophiles
H2 and then sulfur compounds
Why is the Mushroom spring so important?
the discovery of TAQ polymerase, used to replicate DNA.
What happend to chemical reactions with increasing temperatire?
increased number of collisions and increased energy of collisions.
What are the main negative efects of high temperatures?
Protein denaturation
Lipid/membrane fluidity
DNA RNA instability
What exactly happens as proteins denature?
first the quatrenary bonds break followed by the tertiary to undergo an unfolding of the protein. primary and secondary can also break but requires upwards of 150C
Why is heat an issue for membranes?
increase in heat causes increased fluiity, movement, increased permeability. Cant keep things in or out. Cant hold a membrane potential. Death.
Is DNA or RNA more susceptible to heat?
RNA because its structure is critical to its function
What changes occur within proteins to prevent denaturation?
increase in internal bonds
increase in charged residues to attract water.
increase in disulphur bridges
increase in monomers vs polymers
smaller compact
more stabilizers and chaperones
What changes in DNA/RNA allow them to be more stable in heat?
More GC bonds in RNA as they are more stable due to h bonding.
What types of bonds and molecules allow for membranes to be more resistant to heat?
ether bonds, esp tetra ether. creates a solid monolayer.
Replace the proton motive force with a sodium motive force.
How does pressure change with increasing depth?
10m depth = +1atm
What happens with the bends?
partial pressure of nitrogen in the lungs will be greater than that in the tissues at depth so it will move to the tisses. with decomp the nitrogen will exit solution causing bubbles to form in the joints. painful.
What determines how deep one can dive with a snorkel?
max insp pressure and the transmural pressure. Max insp pressure is 82.6 torr, transmural pressure on chest is this at 112cm. so you wont be able to take a breath.
What is another factor other than transmural pressure that will effect your ability to take a breath at depth?
increased dead space in the lungs
What are the AMA divers?
divers who dive 90-120x a day to 20min and hold for up to 5 min
Why were ama divers women?
because women are more tolerant to increased CO2 levels and also have mroe body fat to keep warm
What are the CVD responses to diving?
Decreased HR
Reduced peripheral blood clow
overall less oxygen utilization
How does BP change with diving?
There will be a progressive increase in BP with depth
What factors mediate the dive response?
Facial immersion, cold water,
What are some of the chronic adaptations to breath holdin?
higher body weight
higher upper arm and leg girth
higher grip strength
What are the main ways to conserve oxygen?
Peripheral vasoconstriction
hypoperfusion of visceral organs
brain and retina remain normoxic
Heart lung and brain become a seperate compartment.
What adaptations do mammals have to allow them to deal with waste? CO2
High blood buffering capacity
reduced ventilatory response to CO2
post dive hyperventilation
Why dont seals get the bends?
Because air is compressed out of gas exchange areas so N2 cant diffuse into the bloodstream
What and how does pulmonary barotrauma occur?
occurs when air is not expired when ascending.
What is nitrogen narcosis?
high levels of nitrogen in the tissues leads to abnormal neural function. 60m = 3 drinks
What is oxygen toxicity?
high o2 will iritate the sir passages
constricts cerebral blood flow and alters CNS function
can become toxic at 25m
What does decompression sickness include?
DCS (decompression sickness) AGE (arterial gas exchange)
What is AGE?
bubble formation in the arterial circulation secondary to pulmonary barotrauma
What are the two alternative gas mixtures for divers?
Nitrox - higher o2 and lower n2
Heliox - helium instead of n2. fire risk.
How does having a patent formen ovale effect divers?
major cause of decompression sickness. mix of blood.
What is the height for high altitude?
Very high altitude? Etreme HA?
What is the death zone?
What is the altitude cut off for permament habituation?
What are the main risks at high altitude?
hypoxia, cold, UV Radiation, Arid
What are the physiological changes that occur in acclimitization to altitude?
increased ventilation
increased hemoglobin
increased hemoglobin affinity
increased tissue o2 extraction
decreased CO
What is the HVR?
Hypoxic ventilatory Response
When does the HVR start?
first few hours greater than 1500m
What is the main problem with increasing our resp rate?
respiratory acidosis.
How is a higher rate of ventilation maintained despite decreasing pH?
Overridden by the central (medulary) chemoreceptors.
What hapens to the oxyhemoglobin dissociation curve with altitude?
Shifts left so that with less oxygen available one can use it to a better extent.
What happens to hematocrit with increasing altitude?
Increase in RBC and viscosity.
What are cheyne stokes respirations?
Central apneas and hypoapneas with periods of hyperventilations.
What happens to lung diffusion with altitude?
reduced diffusion of air from the outside into the lungs.
What are the three main altitude syndromes?
AMS - acute mountain sickness
HAPE = high altitude pulmonary edema
HACE - High altitude cerebral edema
At what level will AMS onset?
>2000m, usually 3000
Insidence and severity of AMS depend on?
Rate of ascent, altitude attained, length of time at altitude, degree o physical exertion, individuals physiological susceptibility.
What are the main ways AMS is prevented?
Ascend to a sleeping elevation no more than 500m/day.
Rest every 3-4 days
What are the two pharmacological interventions for AMS?
Acetazolamide - which will acidify the blood and act as a diuretic
Dexamethathasone - antinflamatory that will prevent symptoms
What is HACE and what are the symptoms?
High altitude cerebral edema - occurs when AMS does not redise. Occurs >4000m. Symptoms: Confusion, ataxia, coma, death.
What are the main treatments for ASM or HACE?
Decent, Supplementary o2, portable hyperbaric chamber, pharmacology.
What is HAPE? How does it present?
It is vasoconstriction of the pulmonary capillaries, leading to increased pressure and then edema. Presents similar to pneumonia. Must get down as fast as possible, o2 and CPAP