Regulation of Carbohydrate/Fat Metabolism and Exercise Effects Flashcards
What body systems does exercise involve?
musculoskeletal, cardiovascular, respiratory, endocrine, and immune system
exercise causes:
-increased breathing & heart rate
-increased contraction of muscles
what is caused by increased breathing and heart rate?
provides increased O2 and nutrients, eliminate CO2 and metabolic waste products, transport hormones, maintain body temperature and acid-base balance
what happens with increased muscle contraction?
in response to demand, muscles change in ability to extract O2, choose energy sources and eliminate metabolic waste
Steps of skeletal muscle contraction:
-action potential arrives at neuromuscular junction
-motor neuron is signalled to release Ach
-Ach is released and binds to receptors on muscle cells
-Na ion channels opening leading to action potential in sarcolemma
-action potential travels along T-tubules
-Ca release from SR into cytosol
-Ca binds to troponin, exposing the myosin binding site on actin filament
-myosin binds to the actin to make a cross bridge
-myosin pulls and then detaches from actin (small pulls at a time)
-keeps attaching pulling and then detaching
What is the cross bridge cycle?
-myosin binds to actin with ADP & phosphate molecule
-myosin pulls its head back & releases ADP and phosphate molecule
-ADP turns to ATP and binds to myosin causing it to detach from actin
-ATP–>ADP & phosphate molecule and myosin can rebind and pull again
What regulates muscle contraction?
Ca and ATP
what happens if there is no ATP available during muscle contraction?
myosin cannot detach from actin
*causes rigidity in muscle
Is there only one cross bridge during a muscle contraction?
No. There are many myosin heads on the thick filament
-many cross bridges form and break continuously during muscle contraction
-multiple sarcomeres in one myofibril, multiple myofibrils in one muscle fiber, and multiple muscle fibers in one muscle
What is muscle strength directly related to?
the amount of myofibrils and sarcomeres within each fiber
Type 1 fibers
-slow twitch
-redder in color due to increase in myoglobin
-many mitochondria
-surrounded by more capillaries
-aerobic metabolism for high resistance to fatigue
-postural muscles and used for endurance
-uses aerobic metabolism to make ATP
Type 2 fibers
-fast twitch
Type 2A fibers
-fast oxidative fibers
-hybrid of 1 and 2 fibers
-use both aerobic and anaerobic metabolism to make ATP
Type 2B fibers
-fast glycolytic fibers
-white in color
-low levels of myoglobin
-few mitochondria
-anaerobic metabolism to make ATP
more myosin cross-bridges=
greater force
which muscle type has more myosin cross bridges?
type 2
Are muscles just made of one type of fiber?
No, most muscles are a combination of the two types
-genetics and training can influence the composition
What is sarcopenia?
loss of muscle mass with age
What is atrophy?
muscle loss due to disuse
Sources of ATP required for muscle contraction:
Glycogenolysis, glycolysis, Krebs (TCA) cycle and respiration, and fatty acid oxidation
What is glycogen?
glycoprotein that has a core of glycogenin
-highly branched structure made of glucose molecules connected through 1,6- and 1,4-glycosidic bonds
How is glycogen broken down?
*glycogenolysis
-terminal residue is released as glucose-1-phosphate
-converted into glucose 6-phosphate
-glycogen structure affects the rate at which glucose can be released and used for fuel
advantages to glycogen branching
-allows for better solubility
-allow molecule to fit in smaller spaces
-multiple glucose can be released at the same time
How many molecules of ATP and pyruvate are made with each molecule of glucose in glycolysis?
2 ATP and 2 pyruvate
What is pyruvate converted into in anaerobic respiration?
lactic acid
what does lactic acid contribute to when it accumulates?
muscle fatigue
Why is it necessary that pyruvate be turned into lactate?
to make NAD+ to go electron transport chain
How many ATP can one molecule of glucose make?
32
What determines the capacity of a muscle to do long term heavy exercise?
muscle glycogen
What can affect the amount of glycogen?
diet
-high in carbs before strenuous exercise
What is the cori cycle?
the process of turning lactate back to glucose in the liver
(gluconeogenesis)
How are fatty acids stored most commonly in the body?
triglycerides
kcal/g of fat yield from oxidation
9
kcal/g of carb yield from oxidation
4
how much more energy is stored in fat than glycogen?
6x as much
muscles burning fatty acids must do so….
aerobically
*slower than burning glucose anaerobically & using Cori cycle
What is acetyl CoA made into if there are not enough metabolites for the Kreb’s cycle?
ketones
What are the 4 steps of beta oxidation?
oxidation
hydration
oxidation
thiolysis
*2 C’s removed each cycle
How many ATP can be made by the oxidation of one palmitate?
106
Energy providers during the first hour of exercise?
50% from glycogen, 25% from triglycerides, and 25% from free fatty acids
Energy provider during the second hour of exercise?
glycogen and triglycerides are being depleted faster than they can be replaced
-blood glucose and free fatty acids provide greater percentage
Energy provider during hour three of exercise?
over 70% comes from blood glucose and free fatty acids
Energy provider after 4 hours of exercise?
over 90% of energy made by blood glucose and free fatty acid
-triglycerides provide less than 10%
What does erythriopoietin do?
increases the production of RBC
-this is what Lance Armstrong used to be a fake ass cheater
Which of the following produced during anaerobic glycolysis?
lactate
