Metabolism

Question 1

Physiology

Answer 1

• study of function as related to structure
• systems approach vs. environmental approach
• pyschiological systems are selected for in terrestrial environment - coded for in genome, variability in physiology

Question 2

Claude Bernard and Water Canon

Answer 2

• Claude Bernard - father of physiology
• looked at BG and bp and sodium in humans and found about the same - consistency of internal enviornment
• Walter Canon - homeostasis - maintain consistency of internal environment

Question 3

Framework for looking at System

Answer 3

1. what is the nature of the physiological problem?
2. what are the mechanisms to solve the problem?
3. how is the system regulated?

Question 4

Metabolic Rate - Organismal Metabolism

Answer 4

1. generally the best index of total physiological state - rate of energy utilization
2. tells how hard an organims is working to meet both internal demands (run physiology) and external demands

MR = BMR + Activity + biological processes (reproduction, shivering) + TER

BMR - basal metabolic rate

TEF - thermal effect of food - effect of digestion on metabolism

Question 5

Metabolize Glucose Completely

Answer 5

6O₂ + C₆H₁₂O₆ –> 6CO₂ + 6H₂O + 686 kcal(direct heat production - generates heat via anaerobic and aerobic)

• 6O₂ can be measured w/indirect calorimetry and is only aerobic in LO₂/time (liters of O₂)
• most of our metabolism is aerobic
• can measure O2 consumption and heat production to follow metabolic rate

Question 6

To measure Metabolism

Answer 6

• bomb calorimetry - w/animal in chamber within chamber w/inner chamber surrounded by water
  
  • as animal metabolizes it gives off heat and heats jacket of water
  • calculate heat given off by specific animal
  • T1 - T2 = deltaT
  • volume of H2O; specific heat of water
• System Indirect Calorimetry
  
  • air flow [O₂]
  • delta[O₂] x flow rate = O₂/time
  • capture = 90% of this
  • Cal = kcal

Question 7

To stabilize your MR

Answer 7

• subject @ complete rest, fasted, no thermal stress in TNZ
• human data reported as SMR (standard MR) - rested
  
  • BMR - in humans need them sleeping - harder to do
• SMR humans - women: 1900-2400 Cal/day
  
  • men: 2000-2900 Cal/day

Question 8

Endotherms

Answer 8

• endotherms - regulate body temp @ constant level
• Ta = ambient temperature
• series of Ta w/in TNZ where can make adjustments of body posture and blood to skin w/out > in MR
  
  • MR increases at LCT and UCT
• LCT - lower critical temp
• UCT - upper critical temp (evaporative cooling)
• TNZ - thermal neutral zone

Question 9

UCT - upper critical temp

Answer 9

• evaporative cooling - gets rid of thermal stress from environment
  
  • ex sweating
  • many animals pant - rapid breathing, shallow breaths, air in respiratory tract is saturated w/water vapor
    
    • evaporative cooling of upper respiratory tract
    • at resonant frequency of chest cavity - large structure vibrates w/out lot of energy

Question 10

LCT - lower critical temp

Answer 10

• cold exposure - shivering and nonshivering thermogenesis, > MR - generate heat for constant body temp
• shivering thermogenesis - asymmetric muscle contraction (signal nervous system to contract skeletal system) -> generate heat (> MR, get heat to keep warm) –> directed to body core –> decrease blood flow to extremeties
• nonshivering thermogenesis w/brown adipose tissue (BAT) in babies at neck when born
  
  • sympathetic nervous system sends neurotransmitter: Norepinephrine to BAT tissue where B3 Adrenergic Receptor and temp increases
  • proteins called UCP1 - uncoupling protein #1 (stimulates receptor to turn BAT on)
  • UCP1 is expressed in inner mito membrane and uncouples oxidative phosphorylation
    
    • H+ cross membrane w/out coupling to ATP so tissue gets warm when stimulated
  • blood flow warmed by BAT and use blood circulation to spread heat

Question 11

White Adipose Tissue (WAT) as adults

Answer 11

• clavical area have retroperitoneal area where > in “beige fat” which is BAT that can be turned on to increase MR and > heat production
• “recruitable” - take WAT cells to recruit to generate heat like BAT
• in rodents w/cold exposure they recruited beige fat
• humans have active beige cells - and number varies inversely w/obesity
• possible to recruit/stimulate beige fat cells to treat obesity? B3 adrenegic receptor could be key

Question 12

What influences MR?

Answer 12

• activity
• diet
• overall body size
• highest MR of individual due to activity
• RMR - resting MR
  
  • 12,000 Cal/day
  • 6x more in phelps

Question 13

Endotherms Graph MR vs. Time

Answer 13

• MR (lO₂/hr) vs. Time
• • first is RMR then activity
    
    • see oxidative metabolic scope at 4.3 times
    • see total metabolic scope is aerobic and anaerobic in kcal/hr
• in body skeletal muscle has creatine phosphate which creates ATP from ADP and creatine phosphate; body trying to maintain ATP
  
  • make ATP fast via glycolysis
  • make lots of ATP via oxidative phosphorylation in ETC
  • hit the wall when run out of ability for glycolysis so ATP not fast enough

Question 14

Ectotherms Graph MR vs. Time

Answer 14

• Alligator
• no endurance of oxidative metabolic scope but fast w/glycolysis
• doesn’t have to regulate body temp but MR > by change in body temp a bit
• SMR then has activity and way more anaerobic than oxidative metabolic scope