UROGENITAL (PART 3) Flashcards
What is the body water content of newborns?
Over two-thirds of body weight
Why do active adults have more body water content?
Muscle and metabolically active cells are high in water content
How can body fat content affect body water percentage?
Fat tissue has lower water content that muscle tissue, so an increase in body fat can decrease overall body water percentage
What factors can decrease body water content in older adults?
Lower muscle mass
Decreased kidney function
How does increased plasma osmolality stimulate ADH release?
Osmoreceptors in the hypothalamus sense the increase and signal the posterior pituitary
What triggers the release of ADH?
Increased plasma osmolality (blood concentration)
Decreased blood volume or blood pressure
What are the effects of ADH on the kidneys?
Increase water reabsorption in the distal convoluted tubule and collecting duct
Water moves back into the bloodstream
How does ADH indirectly affect blood volume and pressure?
Increased water reabsorption occurs alongside:
Release of aldosterone (promotes sodium and water reabsorption)
Angiotensin II mediated vasoconstriction (increases blood pressure)
What is the overall effect of ADH on urine output?
ADH increases water reabsorption, reducing urine output
What is the normal body water content at birth?
Majority of body weight (over 60%)
How does body water content differ between adult males and females?
Males have more muscle mass, leading to higher body water content
Females have more fat tissue, leading to lower body water content due to lower water content in fat
Why are newborns susceptible to dehydration?
High metabolic rate and body surface area lead to larger fluid shifts
Immature kidneys reabsorb less water, leading to more excretion
How do ageing kidneys affect hydration?
Reduced kidney mass can lead to dehydration if not careful about fluid intake
Decreased ability to concentrate urine may require increased water intake
Why are older adults more susceptible to electrolyte imbalances?
Reduced ability to regulate sodium and water balance
Increased sensitivity to ANP (increases sodium and water loss)
Reduced renin and aldosterone response (can lead to sodium loss)
Reduced kidney mass limits potassium excretion (risk of hyperkalemia)
