Energy Balance (B) Part 2 Flashcards

Question

what is hibernation? Are there periods of arousal during hibernation even when the metabolic rate drops?

Answer 1

a profound and SEASONAL (longer than torpor bouts) drop in Tb to just over the ambient temperature. results in a drop in metabolic rate of up to 95%. Hibernators must store up large amounts of unsaturated fats (which do not turn hard like butter at cold body temperatures) to serve as energy reserves. There are periodic arousal bouts during hibernation, but shivering and non-shivering thermogenesis powers them. the blue lines on the graph indicate the bouts of periodic arousal

Answer 2

- true hibernators are small animals. bears cannot truly hibernate because they can't get their body temps to lower enough (because of the low SA:vol ratio) the large mass is also expensive to rewarm afterwards. they cannot periodically arouse if they were to drop to Ta temp levels. But, this slight decrease in Tb still saves energy

Answer 3

1) reproduction. MR lowers so much that female animals cannot lactate. there is also delayed parturition (delyaed birth), and slower offspring growth 2) risk of predation 3) physiological costs. sleep deprivation, accumulation of nitrogenous wastes. ex chipmunks do not increase fat stores, they build food stores. Chipmunks with extra food remained NORMOTHERMIC more often (less torpor). They may have not slept much because of nitrogenous waste accumulation.

Answer 4

1) freeze tolerance 2) freeze avoidance

Answer 5

freezing is bad because it causes dehydration and crystallization.Ice crystals form in the ECF and reduce the concentration of water, resulting in water leaving the ICF, causing cellular dehydration 1) ice nucleaors like phospholipids and calcium salts ensure prevent freezing by aggregating in the ECF and reducing the ability to form large "normal" ice crystals in the ECF, thus preventing the movement of water outside of the cell and preventing dehydration 2) intracellular solutes from liver glycogen stores are seen 450 times the normal in wood frogs. this is an **anti-freeze** by lowering the freezing point through simple colligative properties, and creates am osmotic gradient that prevents dehydration: **compatible cryoprotectant.** The cryoprotectant acts as an osmolyte to help keep the cells in osmotic balance with the increasing osmotic pressure in the ECF. prevents water from leaving the cell to form ice crystals.

Answer 6

1) antifreeze proteins or glycoproteins 2) super cooling

Answer 7

These proteins are effective at much **lower concentrations** than the compatible cryoprotectants. They generally contain very **hydrophilic amino acids** and sugar side chains that are thought to bind to growing ice crystals and thus **prevent their growth.** this is seen in numerous species of fish, insects and plants.

Answer 8

Supercooling is a state of water in which the temperature is well below the freezing point but there is no nucleation site to begin ice formation. Supercooling is a dangerous strategy, however, because any encounter with external ice can trigger a catastrophically rapid crystallization of body fluids.

Answer 9

because of the reduced gradient.

Answer 10

They allow their body temp to rise during the day and allows it to decrease at night. With a 6 degree temp fluctuation, a 500kg camen saves approx 4.5 L water a day not maintaining a constant body temperature. it also has the ability to store urea and avoid necesssity to urinate.

Answer 11

1) tolerance; temporal heterothermy 2) heat exchangers 3) active heat loss

Answer 12

1) they have a **temporal countercurrent system** in the nasal cavity which cools arterial blood and conserves water. ## Footnote The inhalation of drier air from the external environment evaporates this water produced by a prior condensation of air and **cools** the surface of the **maxilloturbinal surface** in the nose in preparation for the next breath cycle. In a temporal countercurrent exchanger, the opposing flows of a fluid are separated in **time** (using one tube) rather than in space (using two separate tubes). Mammals on average reclaim as much as 45% of the water (and its heat content) from the exhaled air 2) The **carotid rete COUNTER CURRENT EXCHANGER** that runs parallel to cool venous drainage from the nasal cavity and skin.

Answer 13

1) cools brain 2) prevents brain from shutting down muscles 3) prevents brain from activating evaporation and prevents water loss.

Answer 14

at the upper end of the thermoneutral zone, beofre Ta= Tb, MR BEGINS TO INCREASE. If the heat is not lost, the Tb will rise (bad), so heat must be lost before Ta exceeds Tb. This occurs by INCREASING CAPACITANCE (reducing insulation) Q(heatloss)= C(Tb-ta)

Answer 15

Respiratory panting and insensible CURTANEOUS LOSS through the skin

Answer 16

rapid fluttering of the well-vascularized esophageal region. This rhythmic inflation of the hyoid apparatus is termed gular fluttering.

Answer 17

respiratory alklosis is avoided in part by the rapid and VERY shallow breathing. It uses the DEAD SPACE of the respiratory tract. Panting involves inhaling through the nose and ehaling through the mouth, where condensation is evaporated from the tongue, and allows for the **one-way flow over non-exchange surfaces, so no blood O2/CO2 concentration imbalances occur** **the resonant frequency of the thorax is alos limited, minimizing muscular activity.**

Answer 18

**behavior.** ectothermic individuals select a desired ambient temperature that their body temp works functionally at. this implies the existence of temperature-sensitive neurons in the brain. There are also some cardiovascular adaptations to obtain/retain heat, but behavior modification is the primary source.

Answer 19

they implement diel migration. In order to prevent predation when the juveniles are feeding on surface insects, the optimize forgaing time that gives them enough light to see bugs but prevents them from being seen by a bird. During dawn: they feed at the surface, and in the day, the LOWER THEIR MR and go to the bottom (LOW TEMP) of the thermocline to chill out of sight from predators. at night, they rest above the thermocline in order to have optimum growing temperature.

Answer 20

teleosts are able to maintain a somewhat constant temperature becaused of evolved endothermy, primarily in their **red or aerobic swimming muscles**. These animals migrate over long distances, **swimming continuously with these muscles and generating constant heat output**. But it is not enough to heat the entire body, because too much heat is lost at the gills through CONDUCTION (gills are a limiting factor). A **countercurrent rete system** between the aerobic muscle and the gills prevents most of the loss

Answer 21

during preflight warm-up, some species **shiver their flight muscles before takeoff**. During flight they can keep their thoraxes at **relatively constant** and high temperatures by controlling hemolymph flow between the thorax and abdomen, which are connected by countercurrent flow channels . The abdomen has a thin ventral surface, the **thermal window,** through which excessive heat can be lost. Some insects may also keep warm because of chitin for insulation

Answer 22

In addition to birds and mammals, many other animals (exhibit some form of endothermy, but unlike birds and mammals, **they do not heat all their cores.** Furthermore, some animals including many small birds and mammals **cannot maintain high core tem- peratures continuously,** because of their high ratios of sur- face area to volume, coupled with insufficient food supply. Such animals are called heterotherms, falling into **two broad categories: regional and temporal.**

Answer 23

Regional heterothermy occurs in endothermic animals that heat only certain organs or body regions, not their entire bodies. Temporal heterothermy is manifested in endotherms that regularly shift from a regulated high body temperature to a low body temperature, most commonly in **daily torpor and seasonal hibernatio**n.

Answer 24

hypothalamis

Answer 25

solar radiation, other environmental sources like rocks, muscle activity

Answer 26

shivering has evolved in pythons. This allows for the Tb to increase in order to incubate eggs. Therefore, like many endotherms, the metabolic rate of a python actually goes UP when the ambient temperature FALLS this graph shows that as temp decreases, the number of contractions and the body temperature increases when brooding.

Answer 27

during non breeding, they are pretty ectothermic, Tb= Ta. When they're brooding, there is an increase in heat production, like in pythons, Tb may exceed Ta for some species.

Answer 28

1) avoidance behavior 2) cardiovascular activity 3) gular flutter (like in birds, allows for evaporative heat loss like panting) 4) habitat features: radiation, conduction, convection.

Answer 29

1) avoidance of lethal temperatures 2) greater activity at low ta than conforming Tb's would permit. 3) maintain optimum Tb for efficient enzyme performance. 4) different species may occupy different preferred temperaturees, allows for proper resource partitioning! Occupation of a variety of different ecological niches can reduce competition.

Answer 30

These lizards are able to remain active in high temperatures, and can even tolerate 47 degree temperatures because of special HEAT SHOCK PROTEINS. The 3 D strcuture of proteins help maintain enzyme function.

Answer 31

heatshock protein dissociates and bind to proteins to hold it together to prevent dissociation of other proteins. A portion of the heatshock proteim, HSF1, acts as transcription factor and producs even more HSPs

Answer 32

1) set point regulated in hypothalamus 2) cardiovascular heat gain/retention/loss mechanisms 3) evaporative cooling via gullar flutter 4) capacity for endothermy (limited) ex/ python shivering

Answer 33

1) insulation 2) comparable capacity for aerobic metabolism-- same costs and benefits as mammals and birds.

Answer 34

they are basically completley ectothermic becaues of cutaneous respiration and water dependence. The have even less insulative skin and water loss, which **LIMITS AEROBIC METABOLISM**

Answer 35

the idea that there was selection pressure for a bunch of traits that allowed specieis to run faster and facilitated the production of heat-generating structures and the increased ability to do aerobic respiration. - increased aerobic capacity was a result and allowed subsequent increase in locomotion

Answer 36

the idea that the increased rate of offspring development at higher temperature was beneficial.

Answer 37

the idea that mammals and their therapsid ancestors were around at night when ammales were hunted by dinosaurs. They hi in burrows during day time and came out at night when it was cold. it was beneficial to have HEAT GENERATING MECHANISMS. Even today, most extant mammals are still small and nocturnal. Most mammals can also see better at night than birds or reptiles.

Answer 38

fungi thrive at lower temperature. Upregulating temp via endothermy prevents fungal growth.

Answer 39

the hypothalamus typically controls thermoregulatory proceses. the POSTERIOR hhypothalamus is activated by the cold, and the ANTERIOR hypothalamus is activated by warm temperatures.

Answer 40

1) acclimatization (within lifetime) 2) adaptation (evolutionary time)

Answer 41

1) lipids (esp for membranes 2) proteins

Answer 42

hydrophobic interactions.

Answer 43

physiological systems used to maintain similar levels of membrane viscosity. 1) incrase unsaturation of phospholipids to increase membrane fluidity. hlps with cold temperatures. - this is seenin hibernator diets: they eat polyunsaturated fats because their membranes are kept fluid in the cold 2) de novo synthesis: replace whole regions of membrane 3) in situ synthesis: enzymes modify individual phospholipids

Answer 44

1) shorter chain lenghts = higher fluidity. the longer the phospholipid tails, the more interactions between the tails are possible and the less fluid the membrane will be 2) unsaturation = higher fluidity 3) replacing phosphatidylcholine for phosphatidyletholamine

Answer 45

how fast an enzyme can catalyse a reaction

Answer 46

Enzymes of animals with warm bod- ies, such as mammals, have relatively inefficient (low kcat) enzymes, whereas cold-bodied animals have faster (high kcat) enzymes.

Answer 47

LDH is the final enzyme of anaerobic glycolysis, catalyzing the conversion of pyruvate and NADH to lactate and NAD+. As shownKcat of LDHs is **inversely related** to an animal’s Kcat average body temperature. This is a tradeoff between stability and reaction rate. - high temp endotherms have very stable LDH to resist denaturation. - low temp ectotherms don't need as stable LDH because the risk of denaturation is lower. Warm-adapted LDHs have relatively stiff loops, rigid enough to resist denaturation at higher temperatures. But they are too inflexible to work at cold temperatures. Cold-adapted LDHs have relatively loose loops, able to open and close well in the cold. But they lose their structure more easily at higher temperatures.

Answer 48

in response to microbial invasion, certain white blood cells release a **pyrogen** (espe- cially interleukin-1, IL-1), which acts on the **hypothalamic thermoregulatory center** to raise the setting of the thermostat (see p. 469). The hypothalamus now maintains the **temperature at the new set level** instead of maintaining normal body temperature. some gram-negative (able to be treated with antibiotics) bacteria have exogenous pyrogen (endotoxin) on the cell surface to also induce a fever. the higher Tb may stimulate leukocyte sythesis and phagocytosis. May interfere with bacterial reproduction.

Answer 49

fever is a deliberate attempt to get rid of infection by purposely increasing Tb. this high tb may stimulated leukocyte synthesis and phagocytosis. Hyperthermia is an unintentional displacement of Tb from a fixed set point