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exam 2 metabolism Flashcards

1
Q

the usefulness of metabolic rate

A
  1. quantitative measure of the total activity of the total activity of all an individual’s physiological processes
  2. Determines energy ( or food) requirements
  3. estimate of the drain an animal places on the physiologically useful energy supplies of an environment
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2
Q

BMR vs SMR

A
  1. basal metabolic rate- metabolic rate when an animal is in its thermal neutral zone, fasting, and resting. This applies to only homeotherms and endotherms
  2. standard metabolic rate- metabolic rate when an animal fasting and resting at a specific temperature. Applies to only poikilotherms and ectotherms
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3
Q

Respirometry assumptions

A
  1. most if not all chemical reactions are aerobic
  2. the amount of heat produced when a given volume of O2 is consumed is assumed to be constant irrespective of the metabolic substrate
  3. The O2 stores in the bodies of most mammals are small, so real-time oxygen consumption is assumed to represent metabolic rate accurately
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4
Q

Energy used by an animal

A

Because energy is needed for biosynthesis, maintenance, and the generation of work, because ATP is not stored and must be made as needed, and because in most conditions aerobic metabolism dominates the measurement of respiratory gases is an appropriate method to determine the metabolic rate and changes in O2 consumption can be used interchangeably with energy values

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5
Q

Facts about energy in cell biology and physiology

A
  1. ATP is the energy currency of the cell. The energy stored in its chemical bonds is what provides energy for most cellular processes
  2. ATP is hydrolyzed to ADP plus P, releasing energy from the broken chemical bond, via one of many ATPases
  3. ATP is not stored by cells
  4. ATP is not transported between cells
  5. Each cell must make ATP in “real” time when it needs it.
    - usually via cellular respiration
  6. The mechanisms of ATP production are important because they impact the physiology and performance of cells, tissues, organs, and individuals
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6
Q

Glycolysis

A
  1. glucose to pyruvic acid
  2. 2 NAD are reduced to NADH
  3. Net gain of 2 ATP
  4. No O2 is used
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7
Q

Citric acid cycle

A
  1. Pyruvate diffuses into the mitochondria via a transport protein and is made in to acetyl coA
  2. 8 NADH and 2 FADH2 are formed
  3. 2 ATP are formed
  4. No O2 is used
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8
Q

Electron Transport Chain

A
  1. Sequence of reversible redox reactions ( passing of electrons)
  2. Oxygen is the final electron acceptor
    - oxygen is the only electron acceptor not limited in supple ( supplied continuously to the cell)
    - Reduced to H2O and removed from the cell
  3. Regenerates NAD and FAD to be used again in glycolysis and the krebs cycle
    - Complex 1, 111, and IV all pump protons into the intermembrane space
  4. Coupling the ETC and ATP production
    - ETC creates a proton gradient between the intermembrane space and the inner matrix of the mitochondria
    - energy lost from the molecules in the ETC is harnessed to make ATP from ADP (oxidative phosphorylation)
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9
Q

Oxidative phosphorylation

A
  1. Protons diffuse back into the mitochondrial matrix through a carrier protein, ATP synthase ( a nano turbine that couples ADP with a phosphate)
  2. P/O= number of ATP produced per atom of oxygen reduced to water.
    - The P/O ratio is tightly tied to the proton gradient. Membrane leakage of protons reduces the P/O ratio. 2.3 is as good as P/O gets but can be lower. (maximum ATP yield per molecule of glucose is 25).
  3. In some cells, ATP synthase is bypassed or offset by UCP1 ( uncoupling protein) which allows the flow of protons but without the creation of ATP (P/O=0). UCP1 creates heat
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10
Q

Composition of the adult human body

A

In order of weight ( highest to lowest)
1. proteins (18-20 kj/gram)
2. lipids ( 39-40 kj/gram)
3. minerals
4. nucleic acids
5. carbohydrates (17 kj/ gram)
Proteins and Lipids can be converted into glucose to be used for energy

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11
Q

Stored energy

A
  1. Stored fats in the form of triglycerides are the largest energy stored in the body
    When accessing stored energy:
  2. carbohydrates are catabolized first, followed by fat. Proteins are only catabolized in starved or emaciated animals
  3. Energy available depends on what is catabolized
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12
Q

summary of reactions in fuel metabolism

A
  1. Glycogenesis: glucose to glycogen, lowers blood glucose
  2. Glycogenolysis: glycogen to glucose, increases blood glucose
  3. Gluconeogenesis: Amino acids to glucose, increases blood glucose
  4. Protein synthesis: amino acids to proteins, decreases blood amino acids
  5. Protein degradation: protein to amino acids, increases blood amino acids
  6. Lipogenesis/ Triglyceride synthesis: fatty acids and glycerol to triglycerides, decreases blood fatty acids
  7. Lipolysis: triglycerides to fatty acids and glycerol, increases blood fatty acids
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13
Q

respirometry

A
  1. Estimates heat production indirectly from respiratory gases
    Oxygen consumption and carbon dioxide are used for two measurements
  2. oxygen consumption (ml/hr/kg) can used to calculate rate (kcal/hr/kg)
  3. Carbon dioxide and oxygen ratio are used to determine respiratory quotient- a number that can indicate fuel type metabolized
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14
Q

Respiratory quotient !!!

A

RQ= CO2 eliminated/ O2 consumed
Glucose: 1
Lipids: 0.7
Proteins: 0.8
Assumptions
1. The only substrates metabolized are carbohydrates, lipids, or proteins
2. All reactions are catabolic. No synthesis (anabolism) takes place alongside breakdown (catabolism)
3. The amount of CO2 exhaled in a given time equals the CO2 produced by the tissues in that interval

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15
Q

Reasons for fastings

A
  1. reduce the impact of diet-induced thermogenesis or SDA (specific dynamic action)
  2. Reduce the anabolic reactions ( post-absorptive state)
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16
Q

Factors that affect the metabolic rates of individual animals

A

Large effects
1. Physical activity ( increases)
2. environmental temperature: mammals and homeotherms: ( increases above and below thermoneutral)
Fish and other poikilotherms:
( increases with increasing temperature, decreases with decreasing temperature)
Smaller effects
1. Ingestion of a meal ( increases for several hours)
2. Body size (weight-specific rate increases as body size decreases)
3. Gender( higher in males)
4. Environmental O2 level ( decreases as O2 decreases below a threshold)
5. Hormonal status: variable
6. Time of day: In humans increases in daytime
7. Salinity of water: variable

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17
Q

Specific dynamic action

A

An increase in MR due to digestion of a meal
1. If a resting animal that has not eaten for a while consumes a meal but then remains at rest, its metabolic rate rises afterward- the SDA

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18
Q

Post-absorptive vs absorptive

A
  1. Absorptive state is characterized by anabolic reactions to store blood-based fuel until later
  2. post-absorptive state is characterized by catabolic reactions to increase blood-based fuels
  3. Animals may have regular periods of hyperphagia and fasting results in large internal changes in the digestive tract
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19
Q

Temperature effects on MR in poikilotherms

A
  • approximately exponential, but not quite
  • increases with increasing temperature
  • decreases with decreasing temperature
  • often used in poikilotherms is temperature coefficient Q10, which equals Mrt/MR(t-10). Q10 is between 2-3
20
Q

Metabolic Scaling

A
  1. Smaller mammals have higher weight-specific BMRs than big ones
    - traditionally this relationship was thought to be largely due to heat loss and SA:V ratio
    - likely due to constraints of circulation
  2. The general relationship or power is consistent across phyla, even between poikilotherms
  3. Metabolic rate of a 1 gram animal varies between phyla and between poikilotherms and homeotherms
  4. can log this allometric relationship to linear
21
Q

The effect of body size on weekly food requirements

A
  1. BMR is directly related to daily food requirements
  2. To maintain mass (caloric reservoir), input must equal output
  3. Because relative heart and lung size are similar across animals, small endotherms must also have higher heart and ventilation rates.
  4. Each kg of a small animal requires more foods than each kg of a large animal
22
Q

telemetry

A

modern telemetry devices permit information on O2 consumption to be radioed from a freely moving subject
- determining MR of active animals
- telemetry
- data loggers
- double-labeled water ( helps determine loss of these molecules to eliminate CO2 production)
- works well for wild animals in natural conditions

23
Q

Important physiological trends

A
  1. The maximum metabolic rate in ectotherms is similar to the BMR of a similarly sized endotherm
  2. Maximum MR is roughly 5-10 fold higher than BMR or resting SMR for both endotherms and ectotherms
24
Q

VO2 max

A
  1. VO2 max like BMR shows an allometric relationship with body size
  2. Some animals are capable of higher VO2 max than predicted by mass (pronghorn bc of elevation)
25
Q

Locomotion

A
  1. The cost of locomotion depends on the speed of locomotion ( but the relationship of speed and metabolic cost depends on the type of metabolic cost
  2. The minimum cost of locomotion is lower in large animals than in small animals, regardless of the type of locomotion
  3. The minimum cost of locomotion depends on locomotion type: swimming < flying < walking/running
    - running: linear relationship
    -swimming: J-shaped curve due to drag ( increases in proportion to the square of the swimming speed)
    - flying: due to aerodynamics, flying speed in flapping birds produces a U- shaped curve
    - Optimal speed depends on goal of locomotion : maximize time aloft or distance travelled
26
Q

heat exchange

A
  1. Animals can maintain body temperature by:
    - changing the relative impacts of heat loss/gain by
    - changing resistances to heat loss
    • changing the driving force for heat exchange
      - change metabolic heat production
27
Q

key temperatures

A
  1. Body temperatures can vary from region to region
  2. Even in homeotherms, core temperature and surface temperature are not the same
  3. Some animals have regional heterothermy: maintaining temperatures of specific tissues at different temperatures
28
Q

Blood flow

A
  1. Without countercurrent heat exchange: with this arrangement of blood vessels, blood loses heat steadily to the environment as flows in and out of the limb, and the temperature of the blood steadily declines
  2. With countercurrent heat exchange: when the arteries and veins are close together, allowing countercurrent heat exchange to occur, some of the heat lost from the arterial blood enters the venous blood. The temperature of the venous blood thus rises as the blood travels toward the body
29
Q

endotherms

A
  1. Narrow thermal neutral zones, with tightly regulated body temperatures
  2. regulate through many physiological mechanisms, but also behavioral changes
  3. Acutely respond to temperature changes with metabolic rates that typically oppose the temperature (at least in the lower range in resistance)
  4. Acclimatize to temperature changes through changes in heat production and resistance to heat exchange
  5. May escape the costs of homeothermy through controlled hypothermia (torpor, hibernation) or migration
30
Q

Thermoregulation symptoms

A
  1. Lower critical limit: piloerection, vasoconstriction, warming behaviors, increased thermogenesis
  2. Lower lethal limit: CNS depression, frostbite, decreased metabolism, coma or death
  3. Upper critical limit: sweating or panting, increased water intake, vasodilation, cooling behaviors
  4. Upper lethal limits: dehydration, CNS impairment, convulsions, seizures, coma or death
31
Q

Thermoregulation mechanisms

A
  1. Change in skin temperature
    - peripheral thermoreceptors in skin
    |
    - hypothalamic centers for thermoregulation (body’s thermostats)
    |
    - motor neurons stimulate skeletal muscles: muscle tone, shivering ( adjustments in muscle activity- metabolic heat production)
    - sympathetic nerves: smooth muscle in arterioles in skin: vasoconstriction, vasodilation ) adjustment in loss or conservation of heat
    - sympathetic nerves: sweat glands, sweating, adjustment in heat loss
    - sympathetic nerves: brown adipose tissue: uncoupling of ATP and H+ gradient, adjustments in heat production
32
Q

Newborn rabbits

A
  1. Non-shivering thermogenesis linked to UCP-1
    - UCP-1 is upregulated in BAT by sympathetic stimulation
    - increases in lipid catabolism
    - increases in lipid uptake in cells
    - UCP-1 allows proton flow in ETC without ATP production ( releases more heat)
33
Q

Body temperature

A
  1. Body temperature (Tb) is impacted by MR, but may also influence MR. So variable Tb could in theory explain the relationship between mass-specific MR and mass
  2. When controlled for phylogeny, no consistent relationships emerge between Tb and body mass. Some groups show positive (+) relationships others negative and some no relationship.
34
Q

SA/V

A
  1. As an organism grow its SA/V ratio decreases
  2. Or if comparing animals of two different sizes, the larger animal always has a lower SA/V ratio
  3. SA increases the exchange or flow of materials and heat
  4. Volume, like diffusion distance, decreases exchange or flow
  5. A higher SA/V ratio allows for better exchange or flow
  6. Increasing SA/V ratio creates more heat loss that needs to be replaced metabolically
35
Q

White-footed mice

A
  1. BAT increases in thermogenic capacity and is maintained until adulthood
  2. Fur grows as they age is maintained until adulthood and can even have seasonal shifts.
  3. Can’t individually thermoregulate until after weeks of developments
    Developmental changes
  4. its ability to produce heat internally (endothermy) increases
  5. its ability to retain body heat increases ( it has a lower thermal conductance)
  6. it can tolerate cooler temperatures
  7. it can spend more time out of the nest, or increase its activity

Young mice are less endothermic than adults, they cannot thermoregulate without parental influence and an appropriate microhabitat ( nest with warm siblings)

36
Q

Marsurpial sugar glider

A

Developmental changes
1. RMR becomes more consistent across a variety of ambient temps
2. Tb increases and becomes more stable despite large changes in Ta
3. Thermal conductance, or heat loss, decreases
young sugar gliders are poikilotherms and can’t thermoregulate without a parent

37
Q

brown, white and beige fat

A

Brown
- positive UCP-1 expression
- high mitochondrial density
- multi-locular
- thermogenesis and endocrine function
White
- UCP1 expression negative
- low mitochondrial density
- uni-locular
- energy storage and endocrine function
Beige
- positive UCP-1 expression
- medium mitochondrial density
- multi-locular
- thermogenesis/ endocrine function

38
Q

Reindeer

A

Development and Thermoregulation
1. At one day old, reindeer calves are fully capable of thermogenesis due to fully functional BAT
2. they are also born with well-developed adult-like pelage
3. Tb= 40 c when Ta= - 20 to -25 C
4. Fast growth rate, partly due to high fat content (20%) of mothers milk
5. Probably the most precocial thermoregulation mammal, but patterns are consistent with other large mammals

39
Q

BAT in humans

A
  1. BAT deposits are more extensive ( larger relative mass) in infants than in humans.
  2. Though not to be present in adults, research in 2000s has shown deposits in humans that vary in function with overall metabolic fitness and long-term differences in ambient temperature
40
Q

Hormone basics

A
  1. Hormones are secreted chemical signals that travel to target cells mainly through blood and to the cardiovascular system
  2. Hormones are effective at extremely low concentrations (picomolar)
  3. The action of hormones is often amplified in target cells due to secondary messengers
  4. Mechanims of Action of Hormones on target cells
    - activates catalytic activity
    - alteration in the levels of intracellular secondary messenger molecules
    - direct effects on gene expression
    - change in membrane potential
    - or a combination of these effects
41
Q

Classifications

A

Peptides: not lipid soluble, bind to receptors on the surface of the target cell
amine: most not lipid soluble, bind to receptors on the surface of the target cell
steroids: lipid soluble, bind to receptors inside target cell

42
Q

Lipid insoluble mechanism

A
  1. Bind to a receptor on the surface of a target cell
  2. This leads to transduction
  3. A second messenger amplifies the signal
  4. Carries it to an effector protein to exact transient effects
43
Q

Circulation

A
  1. Deoxygenated blood (oxygen-poor blood) returns to the right atrium of the heart from systemic circulation
    - empties into the right ventricle and is pumped through the lungs
    - blood picks up oxygen and releases carbon dioxide
    - pulmonary vein delivers the newly oxygenated blood to the left ventricle of the heart to enter systemic circulation
  2. oxygenated blood (oxygen- rich blood) in the left atrium empties into the left ventricle. From here it is pumped throughout the body
    - as blood is pumped through the body, active tissues gain O2 and release CO2, so that the blood becomes increasingly more deoxygenated ( never fully)
    - systemic veins deliver the deoxygenated, or oxygen poor blood to the right atrium of the heart where it enters pulmonary circulation
44
Q

Blood vessels

A
  1. Pulmonary arteries
    - branch off of a main pulmonary artery which exits the right ventricle
    - all carry deoxygenated blood to the lungs
  2. pulmonary veins
    - transport oxygenated blood from the lungs to the left atrium of the heart
    Aorta
    - the largest blood vessel in the body
    - exits the left ventricle and transports oxygenated blood to the body
    - distends with ventricular contraction and recoils with relaxation
    Vena cavae
    - two large veins that carry deoxygenated blood from the upper and lower regions of the body to the right atrium of the heart
    - superior vena cava: returns blood from the head and arms
    - inferor vena cava: returns blood from the legs and lower torso, largest vein in the body
45
Q

Coronary circulation

A

The coronary arteries are a network of blood vessels that carry oxygen and nutrient rich blood to cardiac tissue
- The left and right coronary arteries exit from the ascending aorta, just above the aortic valve

46
Q
A

general physiology (3 decks)

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