Option D unit D2

Question 1

Why humans cannot live without water for a prolonged period of time:

Answer 1

• Possible to last three days without water
  Basic substance for all metabolic processes in the body
  –> Catabolic → condensation
  –> Anabolic → hydrolysis
• Regulates body temperature
• Enables transport of substances essential for growth → blood plasma
• Allows for the exchange of nutrients and metabolic end products

Question 2

Comparing water distribution in a Trained vs Untrained person: (similarities - 4, diferences - 5)

Answer 2

Similarities:
* water distributed in the same places of their body (intra and extracellularly)
* the water content of the various tissues remains relatively constant
* Glycogen is stored with about 3g of water for every gram of glycogen
* Fat = low H2O , muscle = high H2O

Differences:
* Trained will have higher water content in plasma - better thermoregulation
* Trained have a lower % of their body composition as adipose tissue/fat which has low water content «10%»
* Trained have higher amounts of muscle glycogen which increase water content
* Trained will have a higher muscle mass which has a high water content «76%»
* Athletes have higher proportion of fat free mass, which contains water = higher water content

Question 3

Maintaining water levels:

Answer 3

water intake has to be equal to water loss ex. water loss = 2.5 L, water intake = 2.5 L

Negative feedback maintains water levels:
Negative feedback - action causes a return to baseline levels → turns off the trigger when returned to normal

Homeostasis
Condition of optimal functioning for the organisms and includes many variables, such as body temp and fluid balance, being kept within certain pre-set limits

Question 4

the kidney - function + structure (6)

Answer 4

• the main organ responsible for water regulation

structure:

Question 5

role of the medulla, loop of Henle, ADH and collecting dust in maintaining water balance of the blood

Answer 5

medulla: high solute to drive osmosis from loop of Henle to body

loop of henle: can absorb H20 and has aquaphorins

collecting dust: can absorb H20 back to body, aquaphorins

Question 6

How hydration status of athletes can be monitored:

Answer 6

1. Urine based
   * Compare urine color (more yellow = less hydrated)
   * Measure urine osmolarity (dilution of level of urine)
   –> High = dehydrated
2. Body mass based
   * How much weight (body mass) was lost during working out - due to sweating and water loss
   –> This assumes no urination
   * Measure mass before and after workout

Question 7

Why endurance athletes (in relation to non endurance athletes) require a greater water intake: (5)

Answer 7

• Ex. of endurance athletes = marathon, ex. Of non endurance athletes = sprint
• Endurance athletes produce and burn a lot of energy (ATP) to undertake their exercise, this creates heat energy
• Heat created is managed through the evaporation of sweat
• Water in sweat comes from body fluids and this needs to be replaced via the consumption of water
• Health risks from dehydration is higher in endurance athletes as their activity lasts longer = higher chance of performing while dehydrated
  –> Higher risk of: cramps, cognitive function, injury

Question 8

Regulation of electrolyte balance during acute and chronic exercise:

Answer 8

1. Acute exercise:
   Acute = single activity
   * Renal excretion: kidneys adjust filtration rates and reabsorption to maintain electrolyte concentrations within acceptable ranges
   * Osmotic pressure: hormone release helps control water reabsorption in response to changes in osmolarity, thereby affecting electrolyte balance
   * Perception of thirst: thirst prompts individuals to consume fluids containing essential electrolytes such as sodium
   * Central nervous system (CNS): Neural signals influence water intake and help maintain overall body fluid balance
2. Chronic exercise:
   Chronic= multiple training sessions in short time / long training sessions
   Increased sweating and potential nutrient losses
   * Enhanced sweat rate: prolonged physical activity leads to higher sweat volumes, increasing the risk of electrolyte imbalances
   * Altered renal function: long term exercise may cause adaptive changes in kidney function (impacting kidneys ability to filter and reabsorb water)
   * Adaptive neural and hormonal responses: over time, the CNS and related regulatory systems may develop altered sensitivity to electrolyte fluctuations

Athletes need to replenish lost electrolytes, primarily sodium, alongside adequate fluid intake

Question 9

where extracellular fluid can be found in body: (6)

Answer 9

• blood plasma and lympth
• saliva
• fluid in the eyes
• fluid secreted by glands and the digestive tract
• fluid surrounding the nerves and spinal cord
• fluid secreted from the skin and kindeys