Exercise Physiology Exam 1

What is homeostasis compared to steady-state to allostasis (Lec1)

homeostasis→ self regulation to maintain steadiness

steady-state→ adjusting to stimuli/temporary instability

allostasis→ recalibration to create new homeostasis conditions

What is the difference between exercise and physical activity (Lec1)

exercise→ repetitive, planned, structured

physical activity→ any body movement that increases EE

Give 2 biological examples of homeostasis. Also, describe what happens when there is “failure” (Lec1)

↑ blood glc → B cells release insulin → ↓HGP & ↓ blood glc

↓ blood glc → a cells release glucagon → ↑HGP

failure: T1D/T2D

Define metabolism and explain the role of enzymes in metabolism (Lec1)

metabolism→ sum or rxn in human body

enzymes→ accelerate rxns to occur; lower E activation barrier

What are 2 important biologic regulators of enzyme activity (Lec1)

temperature (warmer = faster)

pH

also: allostatic regulators (principle driver of enzymes)(includes: ATP & ADP)

What are the 3 basic goals of digestion and absorption? (Lec2)

nutrient breakdown

nutrient extraction

filter toxins

What processes occur in the mouth (Lec2)

chewing

CHO breakdown→ salivary amylase

fat breakdown→ lingual lipase

↑ contact time for enzymes

What nutrient is mainly digested in the stomach (Lec2)

protein (pepsin)

What route does the liver take to make glycogen from dietary carbohydrate (Lec2)

glc→ SI→ portal vein→ liver

or?

liver→ general circulation→ muscle→ liver via hepatic artery

What is emulsification and how does it impact fat digestion (Lec2)

bile emulsifies fat globules

this breaks down the fat into smaller pieces and helps isolate the small pieces and prevents them from sticking to one another

allows lipase to stick to the larger surface area and act more efficiently

How does insulin favor fat storage (Lec2)

• ↓HSL (which is a hormone that breaks down fat)

• ↑synthesis IMTG

• ↑glycolysis → G6P → TCA or adipocytes

• LPL →breakdown TG → FFA + glycerol → FFA stored as fat

What is bile and what does it do (Lec2)

emulsifies the fat

breaks it down into smaller parts

isolates broken down pieces for increased surface area to allow lipase to work

made by liver, stored in GB

How are fats digested (Lec2)

mouth→ lingual lipase

SI→ duodenum (neutralized by sodium bicarbonate), jejunum (absorbed via diffusion, into lymphatic system then into blood via subclavian vein into general circulation

Where does most nutrient absorption take place (CHALLENGE QUESTION; not on the slides but discussed) (Lec2)

SI→ jejunum

Name the 3 stages of the cell being able to provide ATP for biological work (Lec3)

• ATP (stored in muscle; ~4-5 sec)

• PCr (ADP+Pi=ATP; ~15sec)

• glycolysis (glc[6C]→ 2pyruvate[3C] →2lactate[3C])

What is the enzyme involved in the CP/ATP reaction (Lec3) (ATP/PCr)

CK (creatine kynase)

PCr + ADP = ATP + creatine

What are 2 by-products of oxidative glycolysis (Lec3)

pyruvate (product outside the mitoch.) + ATP (product post TCA within the mitoch.)

What are the 3 ways in which CHO in the body contributes to ATP generation? (Lec3)

1. stored in muscle (primary depot)(~300-400g)

2. blood glc (~5g)(used by brain and RBCs)

3. liver lc storage (~70-100g)(secondary depot)(main supply 85%, kidneys 5-10%, SI 0-5%)

What is contribution of muscle glycogen to exercise energy expenditure across exercise intensities (Lec4)

CHO use increases with intensity

CHO main source of E in MVPA

40%-100% use from walk→jog→run

What are 3 metabolic states the body needs energy (Lec4)

basic maintenance

digestion/absorption

PA

What are 3 key enzymes in glycolysis that “push” glucose to pyruvate (Lec4)

HK→ locks glc in cell

PFK→ forces glc downstream (rate limiting step)

PK→ produces ATP, pulls glc to pyruvate

What are mechanisms used to explain why lactate is useful to human

movement? What is the reason it is “bad”?(Lec4)

1. lactate shuttle (glc → lactate in muscle; lactate → heart etc)

2. cori cycle/lactic acid cycle (glc→ lactate; lactate→ liver; lactate→pyruvate→ glc)

3. oxidative glycolysis

What enzyme is key for making acetyl-CoA? (Lec4)

PDH (pyruvate dehydrogenase)

How do reducing equivalents contribute to ATP? (Lec4)

reducing equivalents = NADH & FADH2

via ETC (electron transport chain)

NADH & FADH2 donate their H+ when interacting with complexes & H+ pumps out & some comes back in, the movement in is an E which is stored in bond of ADP + Pi = ATP

What is the chemiosmotic hypothesis? (Lec4)

explains how reducing equivalents contribute to ATP production

What is the relationship between % heart rate, VO2max and RPE? (Lec5)

they all indicate exercise intensity

increase in HR & VO2max cause increase in RPE

RPE #, add “0”, you get bpm (7→ 70 bpm)

HRmax about = to VO2max

What is the traditional intensity (approximately) for fat “burning” based on % heart rate, VO2max and RPE? (Lec5)

low intensity

60-70% HRmax

50-65% VO2max

Is low intensity exercise best for fat burning during exercise? Describe how it may and may not be (HINT % use vs. total kcal expended). (Lec5)

walking 1hr→ ~50%hrmax→ ~350kcal (50%fat) = 175kcal/9→ ~20g burned

run/jog 1hr→ ~75%hrmax→ ~800kcal (20% fat) = 160kcal/9→ ~19g burned

low intensity not much better

What is EPOC and how does it vary during recovery from light, moderate and high intensity exercise (Lec5)

EPOC = post exercises O2 consumption

↑EPOC = ↑EE

low intensity→ O2 max is lower, SS is lower; recovery is shorter and faster

high intensity→ O2 max is higher, SS is higher; recovery is longer and slower

What metabolic processes explain EPOC (Lec5)

transition/spring: ↑ATP, ↑PCr, ~glycolysis, ↓TCA

800m: ~ATP, ~PCr, ↑glycolysis, ↓TCA

long run: ↓ATP, ↓PCr, ↓glycolysis, ↑TCA

why does EPOC happen? why does it remain higher

1. HR

2. ↑ body temp

3. ↑ lactate

4. ↑epi/norepi

Describe the role of active recovery on lactate metabolism (Lec5)

active recovery happens in period of increase O2 entering body (EPOC) & now we are resting, so the O2 finally able to help the lactate back to pyruvate→acetyl-coa, where before ↓O2 availability prevented pyruvate turning to acetyl-coa

What is the predominate fuel source during rest (fasted) (Lec6)

subcutaneous fat

What is oxygen deficit and how does exercise training change the rate to steady-state (Lec6)

oxygen deficit means that fat cannot enter the mitochondria

What is VO2max and describe the 2 main limitations of oxygen consumption? (Lec6)

What are 3 fat depots in the body? Which abdominal fat depot responds most to exercise? (Lec6)

What are the 5 steps for fat oxidation? (know hormones and enzymes too) (Lec6)

What are the 2 “routes” by which amino acids contribute to ATP production (Lec7)

What factors increase the need for protein compared to most situations (Lec7)

What is the normal amount of protein a sedentary person requires compared to an athlete (Lec7)

Why do athletes require more protein in the diet from a physiologic and metabolic perspective? (Lec7)

What is the difference between gross and net energy expenditure (Lec8)

What are 5 factors that affect energy expenditure during walking (Lec8)

Is fat more economical per oxygen in comparison to CHO? How does the influence of oxygen on metabolism impact fuel selection during high intensity exercise (Lec8)

What are the 3 key components of total daily energy expenditure (Lec8)

What is the difference between obligatory and facultative thermogenesis (Lec8)