SF: Chapter 27pt1

total body water percentage: infants

75%

total body water percentage: males

60%

total body water percentage: females

50%

total body water percentage: elderly

45%

total body water is counted in

function of age, body mass, sex, and amount of body fat

What happens to our total water content throughout our lifetime?

decreases

Infants weight composition

low body fat, low bone mass, mostly water

males weight composition

more skeletal muscle with less fat

females weight composition

high body fat and smaller skeletal muscles

adipose tissue water content

least hydrated tissue; 20%

What are the fluid compartments of the body?

intracellular and extracellular

intracellular fluid compartment: volume amount

2/3 vol

What is the total amount of fluid in the body (L)

40L

intracellular fluid compartment: # liters

28L

ICF compartment is looking at all fluid found where?

inside body cells (cytoplasm)

extracellular fluid compartment: volume amount

1/3 vol

extracellular fluid compartment: # liters

12L

ECF is further broken down into?

plasma, IF, other ECF

ECF: plasma is

blood fluid that connects internal to external environments

ECF: IF is found?

between cells

ECF: other ECF ex (6)

lymph, CSF, eye humors, synovial fluid, serous fluid, GI secretions

compartmental exchange between plasma and IF occurs where?

capillary walls

compartmental exchange between IF and ICF occurs where

plasma membrane

water balance def.

water intake equals water output to maintain hydration

water balance: alteration in total water vol has an effect on what? (3)

body fluid solute concentration, BP, IF pressure

water balance: intake

~2500 ml/day

Water balance intake: where water is coming from in diet

60% fluids, 30% foods, 10% cell metabolism

water balance output: insensible water loss def

water loss that we can't really measure; expired air vapor

Where do we have most of our expired air vapor coming from

lungs and skin

What is the estimated percentage of how much water balance is insensible water loss

28%

water balance output: sensible water loss

measurable water loss

water balance output: sensible water loss ex

urine (60%), perspiration (8%), feces (4%)

regulation of fluid intake: what is the thirst center

hypothalamus

regulation of fluid intake: what triggers the thirst mechanism

osmoreceptors, dry mouth, decreased bv/bp

regulation of fluid intake: osmoreceptors

detect ecf osmolality via pm stretch changes from a gain/loss of water

regulation of fluid intake: dry mouth

blood osmotic pressures increase causing there to be less saliva and less water from blood into ducts

regulation of fluid intake: decreased bv/bp

5% decrease/hemorrhage triggers thirst by baroreceptors detecting changes in volume or pressure

regulation of fluid intake: problematic patient ex (3)

1. athletes

2. elderly/confused don't recognize signals

3. renal/CV patients with fluid overload that are still thirsty

regulation of fluid intake: why do we need to do this

need intake to survive and they kidney cannot compensate for long

regulation of fluid intake: obligatory water losses come from

insensible and sensible water loss (500cc/day in urine)

regulation of fluid intake: what do we need to flush out?

metabolism end products/urine solutes

how long does it take the kidneys to excrete excess water out after ingestion

about 30mins

Why is there not an immediate release of excess water after we drink it

delayed response because we need to inhibit ADH release

When does diuresis peak when regulating fluid output

about 1 hour after drinking

When does diuresis decrease to its lowest point

after 3 hours since drinking

Low ADH =

adequate diluted urine

High ADH =

small amount of concentrated urine produced

what other hormones play a role in fluid output regulation

angiotensin, aldosterone, anf

water balance disorders (3) ex

dehydration, edema, and hypotonic hydration

what can cause increase water loss

profuse sweating for a long time and excess alcohol consumption

dehydration, water loss exceeds?

water intake

dehydration creates what fluid balance

negative fluid balance

when does dehydration occur

after hemorrhage, severe burns, excessive diarrhea, vomiting, profuse sweating, water deprivation, diuretic abuse, diabetes I&M

early signs of dehydration

cottony oral mucosa, thirsty, dry flushed skin and decreased urinary output

later signs of dehydration

weight loss, fever, mental confusion, hypovolemic shock

hypotonic hydration def.

water intoxication (overconsumption of water and electrolytes become excessively diluted)

when does hypotonic hydration occur

after overexertion in hot conditions

what is an example of someone who might experience hypotonic hydration

marathon runners

in hypotonic hydration, even plain water causes?

sodium plasma to drop = sudden and severe hyponatremia

hypotonic hydration, if unconscious, what do we give someone

IV hypertonic fluids (saline)

What is necessary to consider with hypotonic hydration when someone is experiencing excessive vomiting or diarrhea

we need to replace those lost fluids

How do cells present in hypotonic hydration

water goes into cells = SWELLING

swollen cells in hypotonic hydration causes

increased intracranial pressure

symptoms of hypotonic hydration

severe H/A, confusion, nausea, muscle cramps, seizure, coma, death

how to prevent hypotonic hydration

drink fluids that contain electrolytes (gatorade or powerade)

how to treat hypotonic hydration

administer hypertonic saline to reverse osmotic gradient/pull water out of the cells

in dehydration, how does water move?

OUT OF THE CELL

In hypotonic hydration, how does water move?

INTO THE CELL

In fluid balance, how does water move?

equally in and out of the cell

dehydrated cells appearance

shriveled

overhydrated cells appearance

swollen