Quiz 3: water and salt pt 1 Flashcards
food sources of water
all foods
most essential nutrient
water
most water comes from
beverages
osmolarity =
conc of solute/1L
functions of water
- chemical rxns
- body temp regulation
- lube + protection
- solvent + transport medium
- maintenance of fluid volume
- acid-base balance
water output depends on
physical activity
methods of water output
insensible - skin
insensible - lungs (breathing out)
sweat
urine
feces
prolonged heavy exercise =
more excretion via sweat so we excrete less via other methods
where in metabolism do we make water
- FA oxidation
- cellular respiration
normal person what happens to most of the water they ingest and make
it is excreted
water intake
food:
bevs:
water intake
food: 25-35%
bevs: 65-75%
in the US do we get enough water
no
water intake for
men
women
water intake for
men: 3.7 L
women: 2.7 L
water intake needs vary based on (2)
activity level
energy intake
water recommendation
25-40 mL per kg of body weight
body is __% water
newborns are __% water
body is 50% water
newborns are 75% water
__ is way in and way out for water
plasma is way in and way out for water
which has more water: IC or EC
IC
in order, pools of water
IC > interstitial fluid > plasma
EC fluid = __ + __
EC fluid = plasma + interstitial fluid
volume of EC and IC must be in
perfect balance
__ and __ are highly regulated
water and osmolarity are highly regulated
isotonic =
hypotonic =
hypertonic =
isotonic = happy
hypotonic = cell swells
hypertonic = cell shrinks
hypotonic can occur during
parenteral nutrition
swelling of cells causes
edema
hypertonic cells occurs with
too many electrolytes
to fix hypotonic, we need
increased excretion, but keep electrolytes (rly hard to do)
to fix hypertonic, we need
hydration!
__ membrane is barrier btwn plasma and intestitial fluid
capillary membrane is barrier btwn plasma and intestitial fluid
bidirectional flow of water depends on
needs of cell
osmotic pressure balance steps
- blood brings oxygenated blood into artery, out of vein
- capillary membrane removes CO2
- heart makes hydrostatic pressure (pushes plasma)
- hydrostatic P offsets osmotic P of particles in circulation
- net passage of water to EC compartment
- OR, as blood goes through it loses BP, enough to bring water into circulation
main electrolytes
Na, Cl, K
2 electrolyte functions
- control of EC fluid volume
- control membrane potential in excitable cell
main sodium dietary source
sodium chloride
__% of sodium in typical US diet is from processed foods
70% of sodium in typical US diet is from processed foods
no natural, unprocessed foods rich in sodium
high sodium =
low sodium =
high sodium = processed foods
low sodium = meats, fruits and veg
table salt =
sea salt = himalayan salt
in % sodium
main dietary source of potassium
vegetables!
all foods though
is potassium a nutrient of concern
yes, intake in US is low
intestine sodium absorption 2 options
- passive paracellular (by solvent drag, absorbed with water)
- facilitated transport
- Na-glucose cotransporter (SGLT)
- electroneutral absorption of Na and Cl (Na/H: NHE, Cl/HCO3: DRA)
- electrogenic absorption: ENaC (colon!)
main water transporter
SGLT1
SGLT steps
- SGLT moves Na and glucose in
- glucose out by GLUT2
- Na out by NaK ATPase
electroneutral absorption of Na and Cl
- NHE –> Na in, H out, DRA: Cl in, HCO3 out
- Cl- leaves via channels
- Na+ leaves via ATPase
electrogenic absorption of Na steps
- Na in via ENaC
- Na out via NaK ATPase
electrogenic absorption is increased by
aldosterone
main absorption ofNa in colon
electrogenic absorption
ENaC
__% potassium absorbed, but it is not abundant
85% potassium absorbed, but it is not abundant
potassium intestinal absorption options
- passive transport at high conc
- active at low conc by:
- K H ATPase
- K channels
__% of Na, K, Cl absorbed
85-99% of Na, K, Cl absorbed
where are Na, K, Cl mainly absorbed
small intestine
when there is excess K, there is net
when there is excess K, there is net secretion of K in colon
2 roles of Na, K, Cl
- EC fluid volume
- membrane potentials
main osmotic particle
Na
most abundant cation and anion in EC
Na+
Cl-
also Ca2+, HCO3-
most abundant cation and anion in IC
K+
PO4 3-
also Mg
non-electrolytes in plasma contribute little
EX
phospholipids
cholesterol
fat
what controls electric potential
Na K ATPase
Na K ATPase steps
- transporter picks up 3 Na+ inside
- ATP binds + phos 1 aa –> 3 Na+ out
- picks up 2 K outside
- phosphate hydrolyzed release
resting potential =
-70 mV
action potential
- stimulus –> open Na channels, Na in
- depolarization (+) to +30 mV
- Na close, K+ opens –> K+ out
- repolarization (-)
cholride in gastric acid secretion steps
- Cl- in, HCO3- out
- K+ in, H+ out
- Cl- crosses out
chloride functions
- phagocytosis in WBC
- exchange Cl for HCO3- in RBC (chloride shift) –> allows transport of CO2 back to lungs in form of plasma HCO3-