Option D: Nutrition

Question 1

What is digestion?

Answer 1

Digestion is the breakdown of food into small molecules which are then absorbed into the body

Question 2

What are the 2 groups you can group the features of the digestive system into?

Answer 2

->

Question 3

What 7 processes occurr in the digestive system during the treatment of food?

Answer 3

1. Ingestion- process of eating/intaking food
2. Propulsion- movement of food along digestice tract. Peristalsis: series of alternating contractions & relaxations of smooth muscle, lining walls of digestive organs, which forces food to move forward
3. Secretion- of enzymes & other substances liquifies, adjusts pH & chemically breaks down food
4. Mechanical digestion- process of physically breaking down food into smaller pieces. Chewing food, muscular churning of stomach, additional churning in small intestine via muscular constriction of intestinal wall
5. Chemical digestion- process of chemically breaking down food into simpler molecules, carried out w/ enzymes in stomach & small intestines
6. Absorption- movement of molecules (by passive diffusion, active transport) from digestive tract -> adjecent blood & lymphatic vessels. Entrance of digested food, now nutrients, into body
7. Defecation- process of eliminating undigested material through anus

Question 4

Outline the features of the principal components of the digestive system.

1.1

Answer 4

mouth- mechanical digestion and chemical digestion
esophagus- peristalsis action
stomach- rugae, lumen, mucous coating
small intestine- villi and microvilli increase area for absorption
large intestine- water balance, vitamin absorption
pancreas- production of enzymes
liver- production of bile
gall bladder- storage of bile

Question 5

1.1

Explain the role of the mouth in the digestive system

Answer 5

Mechanical digestion & chemical digestion

Beginning of digestive process: chewing. Salivary glands make saliva (digestive juice), moisten food to simplify movement through esophagus into stomach. Saliva also has an enzyme (amylase) that begins to break down starches in your food. Food starts to move through GI tract (gastrointestional tract) when you eat. Swallow: tongue pushes food into throat. Epiglottis folds over trachea to prevent choking & the food passes into your esophagus.

Question 6

1.1

Explain the role of the esophagus in the digestive system

Answer 6

Peristalsis action

Swallowing: process is automatic. Brain signals muscles of the esophagus-> peristalsis begins. When food reaches end of esophagus, ringlike muscle – lower esophageal sphincter – relaxes & lets food pass into stomach. Sphincter usually stays closed to keep what’s in your stomach from flowing back into your esophagus

Question 7

1.1

Explain the role of the stomach in the digestive system

Answer 7

Rugae- series of ridges produced by folding wall of organ – gastric rugae in stomach. Allows stomach to expand when needed.

Mucous coating– protects gastric mucosa from autodigestion by pepsin and erosion by acids. After food enters stomach, stomach muscles mix food & liquid w/ digestive juices. Stomach slowly empties its contents, called chyme, into your small intestine

Question 8

1.1

Explain the role of the small intestine in the digestive system

Answer 8

Absorption

Villi and microvilli increase area for absorption. Muscles of small intestine mix food w/ digestive juices from pancreas, liver and intestine. Push mixture forward for further digestion of proteins, carbohydrates and fats. Walls of small intestine absorb water & digested nutrients into bloodstream. As peristalsis continues, waste products of the digestive process move into the large intestine.

Question 9

1.1

Explain the role of the large intestine in the digestive system

Answer 9

Water balance and vitamin absorption

Waste products from digestive process include undigested parts of food, fluid, older cells from lining of GI (gastrointestinal) tract. The large intestine absorbs water & changes waste from liquid into stool- the water moves from GI tract into bloodstream. Bacteria in large intestine help break down remaining nutrients and make vitamin K. Peristalsis helps move the stool into your rectum.

Question 10

1.1

Explain the role of the pancreas in the digestive system

Answer 10

Pancreas makes digestive juice that has enzymes that break down carbohydrate, fats and proteins. Delivers the digestive juice to the small intestine through small tubes called ducts.

Question 11

1.1

Explain the role of the liver in the digestive system

Answer 11

Liver makes digestive juice called bile that helps digest fats and some vitamins. Bile ducts carry bile from your gallbladder for storage, or to the small intestine for use.

Question 12

1.1

Explain the role of the gall bladder in the digestive system

Answer 12

Gallbladder stores bile between meals. When you eat, your gallbladder squeezes bile through the bile ducts into your small intestine

Question 13

State the typical pH values found throughout the digestive system.

1.2

Answer 13

Mouth: 5.5 to 7.5
Stomach: 1.0 to less than 4.0
Small intestine: 6.0 to 8.0

->Different organs function at their optimal level of pH

Question 14

Describe the function of enzymes in the context of macronutrient digestion.

1.3

Answer 14

Enzyme- protein that acts as a biological catalysts to break down macronutrients/speed up the metabolism
Biological Catalyst- substance that enables chemical reactions to proceed at a usually faster rate or under different conditions (as at a lower temperature) than otherwise possible.

Body temperature & digestion:

D. can occur at body temperature at slow rate. For rate of digestion to increase, body temperature would have to increase accordingly, however this would interfere w/ other body functions
Enzymes vital:
1. Lowering activation eneryg required for reaction to occur to speed up chemical reactions (at body temp.)
2. Specific to substrate they act on
3. Function best at optimum temp. & pH (pH different in diff. areas of digestive tract)

Question 15

Explain the need for enzymes in digestion

1.4

Answer 15

• Enzymes break down large food molecules into smaller ones (for absorbtion)
• Speed up the process of digestion by lowering the activation energy for the reaction.
• at normal body temp. digestion works at a slow rate. Body cannot increase overall temp. bcus it would interfere w/ other bodily functions -> enzymes lower activation energy required for reaction (at body temp.) to speed up digestion

Question 16

List enzymes responsible for digestion of macronutrients
1.5

Answer 16

Carbohydrates: salivary amylase, pancreatic amylase

Fats: pancreatic lipase
* bile produced by liver & also involved in digestion

Proteins: pepsin, trypsin

Question 17

Describe the absorption of glucose, amino acids & fatty acids from the intestinal lumen to the capillary network.

1.6

Answer 17

Absorption of amino acids & glucose absorbed:
* lumen found in small intestine
* cross brush-border membrane (microvili), pass through cytosol of absorptive cell, cross basolateral membrane, enter capillary network

How are fatty acids absorbed?
* Intestinal cells absorb fats
* Cross brush-border membrane (microvili), pass through cytosol of absorptive cell, cross basolateral membrane, enter lympathic system
* Long chain fatty acids form large lipoprotein structure called: chylomicron- transport fats through lymph system
* Short & medium fatty chains absorbed directly into bloodstream from intestinal microvillus (they’re water-soluble)

Question 18

State the reasons why humans cannot live without water for a prolonged period of time.

2.1

Answer 18

Water is:

basic substance for all metabolic processes in body
* chemical reactions take place in aqeous solutions
* make up large amount of human body

regulates body temp.
* e.g. sweating

enables transport of substances essential for growth
* water makes up plasma, cells & extracellular areas

allows exchange of nutrients & metabolic end products
* concentration gradients, solute concentrations
* allow for movement of materials/water

Question 19

State where extracellular fluid can be located throughout the body

2.2

Answer 19

Extracellular fluid includes:
* blood plasma & lymph
* saliva
* eye fluid
* fluids secreted by glands & digestive tract
* fluid surrounding nerves & spinal cord
* fluid secreted from skin & kidneys

Question 20

Compare water distribution in trained and untrained individuals

2.3

Answer 20

Water distribution dependent on body composition

1. Trained athlete has greater water content in body, intra & extracellularly
   * Muscle contains 65–75 % water (glycogen stores -> store more water) : Fat mass is 5–20 % water
   * Exercise training increases & water distributed within the intracellular compartment
2. Trained athlete’s sweat is more dilute than untrained, affects water distribution during exercise
3. Trained athlete has improved temperature regulatory process
4. Trained athlete has increased blood plasma volume

Question 21

Explain that homeostasis involves monitoring levels of variables and correcting changes in levels by negative feedback mechanisms.

2.4

Answer 21

Question 22

Explain the roles of the loop of Henlé, medulla, collecting duct and ADH in maintaining the water balance of the blood.

2.5

Answer 22

Question 23

Describe how the hydration status of athletes can be monitored

2.6

Answer 23

Urine Color
- urinalysis: observing urine colour & using colour scale to compare

Urine Osmolarity (amount of solute per unit volume)
- medical test: Measurement of urine osmolality (concentration of particles in urine)

Variation in Body Mass Loss
- measuring body weight in morning to show pattern of hydration overtime
- can be measured in endurance events, before & after -> provide indication of hydration status of athlete

Question 24

Explain why endurance athletes require a greater water intake.

2.7

Answer 24

The more energy athlete expends = the greater are their fluid needs. Heat is byproduct of energy production & excess heat must be transferred from body to environment to maintain normal body temperature -> Sweat. Evaporation of sweat from the athlete’s body is the primary way of dissipating excess heat.
Sweat loss varies among athletes and can exceed 1.5 liters per hour.

Water intake helps:
- maintain hydration/avoid dehydration
- maintain body temperature/thermoregulation
- maintain plasma volume

Water loss during prolonged exercise:
May lead to:
- decline in athletic performance
- serious medical problems (heat exhaustion, heat stroke)
- stress on the cardiovascular system
- inadequate heat transfer to skin and environment

Is associated w/:
- increased plasma osmolality
- decreased plasma volume
- may affect intracellular & extracellular electrolyte balance

Question 25

Discuss the regulation of electrolyte balance during acute and chronic exercise.
2.8

Answer 25

acute exercise- exercise of relatively short duration/single session of exercise
chronic exercise- very demanding workout routine, can involve intense exercise on a daily basis
* exerction over 60min (or in hot/humidity): water & sodium loss via sweat put antletes at risk for: hypovolemia, dehydration, imbalances in serum sodium & potassium

Sports induced fluid & electrolyte imbalances:

hypohydration:
- loss of min. 2% body water w/o replacement during exercise >20min
- water loss>electrolyte loss (hot conditions)
- accelerates muscle fatigue during exercise & impairs cooling

hyponatremia:
- excessive water intake
- large water amounts (>2-3L) are used alone as replacement fluid -> risk for hemodilution of electrolytes
- symptoms: alteration mental status (e.g. coma & generalized tonic-clonic seiizures)
- sodium fall associated w/ onset of altered mentation

hypokalemia:
- lower than normal potassium level in your bloodstream
- potassium lost in sweat difficult to determine, likely negligible for acute exercise (<30min)
- During exercise, skeletal muscle loses potassium during repetitive action potentials -> most athletes dont require K+ replacement (unless prolonged, hot/humid environment)
- Symptoms: weakness, myalgia of weightbearing muscle, irregular/rapid heartbeat, nausia

Question 26

Discuss the regulation of electrolyte balance during acute and chronic exercise: THERMOREGULATION

2.8

Answer 26

Regulation of water balance required to control body temp. Sweating = cooling mechanism, due to the evapooration of sweat on skin. Sweating needs to be compensated w/ water otherwise hypohydrated state & body temp. increases. Repeated exposure to hot environment: body adapts.

Question 27

Define the term basal metabolic rate (BMR).

3.1

Answer 27

Minimum energy requirement for maintenance of biological activity in the body.

Question 28

State the components of daily energy expenditure.

3.2

Answer 28

Basal Metabolic Rate (BMR)
Thermic Effect of Physical Activity
Thermic Effect of Feeding

Question 29

Explain the relationship between energy expenditure and intake.

3.3

Answer 29

Energy Intake- occurs intermittently through food consumption
- energy stores comprise fats, stored in adipose tissues under skin & carbs in mucles + liver
- protein can be used for energy, but aren’t stored for energy -> have distinct biological role, therefore not used to not disrupt other bodily functions

Energy Expenditure- occurs constantly yet expend rate is variable
* Basal Metabolic Rate (BMR)
* Thermic Effect of Physical Activity
* Thermic Effect of Feeding

Energy Balance
- Energy intake & energy expenditure in healthy adults are balanced
- if energy balance disturbed causes either net gain or loss in body mass

Question 30

Discuss the association between body composition and athletic performance.

3.4

Answer 30

Body composition- body’s amount of fat mass (FM) relative to fat-free mass (FFM)

• FFM mass: lean mass & skeletal muscle mass
• FM mass: simply fat mass stored in adipose tissue

Body shape, size, composition linked w/ sport success-> optimal body morphology for success in diff. types of effort

Typical levels of FM & FFM:

• varies w/ age, gender, genetics, diet, physical activity level
• women tend to have higher FM than men
• competitors in range of sports, gender difference persists but there is variation in FM & FFM across different sport
• too low FM (<5per cent for men or <12 per cent for women), or too high= health threatened

How can FM and FFM be measured?
Expressing amount of FM & FFM in kg/% of body mass= simple idea, difficult measurement
- need to directly quantifying the amount of tissue in the body via cadaveric dissection
- indirect approaches are used but they are less accurate

Accurate:
- Skinfold caliper measures
- Bioelectrical impedance
- Underwater weighing
- Dual x-ray absorptiometry (DEXA)

Strength & Power sports
- body mass isn’t limiting factor -> athletes may have high levels of adipose tissue
- muscular

Endurance athletes:
- small and slender tendency due to increased energy expenditure

Question 31

What physiques are typically associated w/ different sports?

3.4

Answer 31

Question 32

Discuss dietary practices employed by athletes to manipulate body composition

3.5

Answer 32

1. Gaining Muscle Mass (FFM)
   - adequate protein intake (high protein diet) must be consumed in addition w/ correct strength training
   - change in body composition occur slowly over time as result of this strategy
   - excess protein cannot be stored in body & is excreted
   - risks associated w/ excessive protein intake: damaging kidneys, causing dehydration & constipation
2. Reducing Fat Mass (FM)
   - low energy intake/negative energy balance causes body to metabolize stores of fat -> causing weight loss
   - associated w/ lean athletes & women
   - risks w/ loosing excessive levels of body fat: can prevent normal body functioning (e.g. amenorrhea, electrolyte imbalance, gall stone development)
3. Dehydration
   - participants may deliberately avoid/restrict food & fluid intake to remain weight category or gain lower weight category (e.g. boxing/MMA)
   - risks: impact on functioning of cardiorespiratory system

Controversial methods:
- weight bulking powders
- Diet pills
- Fad diets
- Crash diets

Question 33

State the approximate glycogen content of specific skeletal muscle fibre types

4.1

Answer 33

1. slow twitch (type I)—low-glycogen content
2. fast twitch (type IIa)—medium-glycogen content
3. fast twitch (type IIb)—high-glycogen content.

*Type IIa and type IIb are high in glycogen content depending on training status.

Question 34

Describe, with reference to exercise intensity, typical athletic activities requiring high rates of muscle glycogen utilization.

4.2

Answer 34

As exercise intensity increases, muscle glycogen constitutes greater protion of energy source

High intensity (e.g. requiring energy bursts)
- uses fast twitch fibers
- anaerobic metabolism
- Glycolysis will demand high glycogen rates

Low intensity (e.g. training run)
- uses slow twitch fibers (type 1)
- Resynthesis of ATP, will be aerobic -> Krebs Cycle

Question 35

Discuss the pattern of muscle glycogen use in skeletal muscle fibre types during exercise of various intensities.

4.3

Answer 35

As exercise intensity increases, there’s increased contribution to overall energy supply provided by glycogen

Glycogen used aerobic & anaerobic activities to synthesize ATP
- Continuous moderate exercise uses slow twitch muscle fibers ->low rate of glycolysis
- High intensity exercise uses fast twitch fibers -> high glycogen rates
- High intensity: 75% VO2max , 85% max HR

Question 36

Define the term glycemic index (GI).

4.4

Answer 36

Glycemic index (GI)- the ranking system for carbohydrates based on the immediate effect of the food on blood glucose concentrations when compared with a reference food such as pure glucose.

Question 37

List food with low and high glycemic indexes.

4.5

Answer 37

High (glucose, dates) =100
Medium (banana, brown rice) = 50
Low ( green vegetables) = less than 15

Question 38

Explain the relevance of GI with regard to carbohydrate consumption by athletes pre- and post-competition.

4.6

Answer 38

Generally

before exercise: Low GI
* slow energy release, stable blood sugar levels, reduced insulin, increase use of fats

during exercise:High GI
* rapid digested & absorbed, fast release to supply energy

after exercise:High GI
* increased rate of muscle glycogen synthesis & restorage, aids refuelling prior future training

usual meals:Low/moderate GI
* Some evidence that lower GI foods may be beneficial prior to exercise & that general diet (for good health) should be based on carbohydrate foods with a low to medium GI

Question 39

Discuss the interaction of carbohydrate loading and training programme modification prior to competition.

4.7

Answer 39

Carb-loading:
- tactic high-intensity endurance exercise athletes -> maximixe body’s glycogen stores up to 300%
- normal glycogen stores unsufficient for such exercise
- glycogen store depletion causes inadequate fueling of muscle, induces fatigue & diminished performance

Steps to take:
- tapering: reduce training intensity & duration by 50% prior competition
- goal: keep physical adaptations of training process, eliminate neg. effects (fatigue, muscle soreness)
- increase carb daily intake to 8-10g per body kg -> 70-80% carb for daily calories
- carbs low in GI index (sweet potatoes, brown rice, quinoa)

Question 40

State the reasons for adding sodium and carbohydrate to water for the endurance athlete.

4.8

(CHO=Physical work capacity and carbohydrate availability)

Answer 40

• CHO best energy yield per mole of oxygen, compared to proteins & fats bcus. improve physical performance by delaying depletion of muscle glycogen
• CHO-electrolyte functional sport drinks (those containing Glc-Fru and sodium) improve athletic performance by sustaining metabolism & optimizing water absorption, electrolytes enhance fluid absorption in gut
• CHO intake has anti-fatigue effect by maintaining high levels of glucose in blood supporting muscle energy production
• Glc-Fru mixture: capacity to absorpt greater amount of exogenous CHO in systemic circulation, immediate energy fuel

Question 41

Discuss the use of nutritional ergogenic aids in sports.

4.9

Answer 41

ergogenic aid: performance enhancer giving mental/physical edge during exercise

1. Sport drinks, bars, gels
   * formulated around macro- & micronutrients
   * convenient means of ingesting fluid/nutrients
   * numerous compounds & supplements not based on essential components of diet, yet still marketed as sport nutrition supplements

see rest in image below

Question 42

State the daily recommended intake of protein for adult male and female non-athletes.

4.10

Answer 42

Per day:

0.8 g/kg of body weight

exercising/training 5+ per week: 1.2-1.7 g/kg

Question 43

List sources of protein for vegetarian and non- vegetarian athletes.

4.11

Answer 43

Question 44

Discuss the significance of strength and endurance training on the recommended protein intake for male and female athletes.

4.12

Answer 44

athlete protein needs > average sedentary human –> exercise effect on metabolism

• endurance athletes, metabolize proteins differently during long-lasting activity: 1.2 to 1.4 g/kg of body weight per day
• strength-training athletes, muscles tear & protein required to repair & rebuild muscles: 1.2 to 1.7 g/kg of body weight per day

Question 45

Outline the possible harmful effects of excessive protein intake

4.13

Answer 45

• high cholesterol & higher risk of cardiovascular disease
• Increased cancer risk
• kidney disease & kidney stones
• weight gain
• constipation, diarrhea