Fluid Electrolyte Acids & Bases HAN 202

Body water content infants

73% or more water (low body fat, low bone mass)

Body water content adult males

60% water

Body water content adult females

~50% water (higher fat content, less skeletal muscle mass).

Water content declines to ____ in old age

45%

Daily recommended amount of water

8 cups

intracellular fluid is how much percent of body weight

40%

Interstitial fluid is how much percent of ECF

80%

Plasma is how much percent of ECF

20%

The total body water is what and what combined

ICF and ECF

Extracellular fluid is how much percent body weight

20%

Major cation of ICF

K+

Major anion of ICF

HPO4(2-)

Major cation of ECF

Na+

Major anion of ECF

Cl-

Each fluid compartment has distinctive patterns of

electrolytes

What regulates fluid movement among compartments

osmotic and hydrostatic pressures

Water moves freely by what

osmosis

Osmolarities of all body fluids are almost always

equal

What leads to net water flow

change in solute concentration of any compartment

An increase in ECF solute causes water to

move out of cells

A decrease in ECF solute causes water to

move into cells

During osmosis water flows from

lower solute concentration to higher solute concentration

Water gain is caused by

metabolic water, cellular respiration, food, drinks

Water loss is caused by

urine, feces, cutaneous transpiration, expired air, sweat

cutaneous transpiration

water evaporates from skin

what mechanism is the driving force for water intake

thirst mechanism

Hypothalamic osmoreceptors

trigger or inhibit ADH release

ADH

antidiuretic hormone

function of antidiuretic hormone

promotes retention of water by kidneys

ADH is a regulator of

water output

renin-angiotensin-aldosterone system

a hormone cascade pathway that helps regulate blood pressure and blood volume

What does an increase in osmolality of 1-2% do

stimulate the hypothalamic thirst center osmoreceptors

What does angiotensin II do?

-Increases aldosterone production in adrenal cortex

What is aldosterone?

Secreted from the adrenal cortex and promotes sodium, chloride, and water reabsorption in the kidneys.

Angiotensin II or baroreceptor input stimulates what

hypothalamic thirst center osmoreceptors

Dry mouth causing less saliva stimulates what

hypothalamic thirst center osmoreceptors

What does a substantial blood volume or pressure stimulate

hypothalamic thirst center osmoreceptors

What hormone regulates water output

antidiuretic hormone (ADH)

What is renin

enzyme that converts angiotensinogen to angiotensin I

The first step in the renin-angiotensin mechanism is:

blood pressure falls, renin is released by the kidneys into the bloodstream

Second step in Renin Angiotensin System

Renin splits angiotensin ( a protien made in the liver) into angiotensin I and angiotensin II

angiotensin I

Inactive. Converted in lung capillaries to Angtiotensis II (active) by ACE (made in lungs).

ACE

Angiotensin Converting Enzyme Inhibitor, converts inactive angiotensin I to angiotensin II

Angiotensin II

increases blood pressure by stimulating kidneys to reabsorb more water and by releasing aldosterone

What releases aldosterone?

adrenal glands

What releases ADH?

pituitary gland

Together what do aldosterone and ADH do

cause your kidneys to retain sodium. Aldosterone also causes your kidneys to release (excrete) potassium through your urine.

The last step in renin angiotensin system

aldosterone and ADH cause your kidneys to retain sodium, which causes water retention

What is the purpose of renin angiotensin

increases blood volume and blood pressure in response to low blood pressure

Hypothalamic osmoreceptors trigger or inhibit the release of what

ADH

What does a decrease in ADH cause

dilute urine and decrease of the volume of body fluids

What does an increase in ADH cause

concentrated urine

What is the purpose of antidiuretic hormone (ADH)

it helps prevent diuresis (too much urination) and conserves water in body

Electrolytes are

salts, acids, bases

Examples of electrolytes

sodium, potassium, chloride, calcium, magnesium, phosphates

Eating a meal high in salt (NaCl) will cause what

a temporary increase in blood volume

What is the most abundant cation in the ECF

sodium (Na) 90-95%

What cation is responsible for resting membrane potential

sodium (Na+)

What regulates Na (sodium) balance

Aldosterone

Aldosterone

"salt-retaining hormone" which promotes the retention of Na+ by the kidneys. na+ retention promotes water retention, which promotes a higher blood volume and pressure

The regulation of sodium is linked to

blood pressure

If you have high blood pressure, what do you need to be aware of

sodium intake because sodium holds water

What is released when BP or blood volume is low

Aldosterone

ANP Atrial Natriuretic Peptide

Secreted in response to excess blood volume in the heart, promotes salt and thus water excretion.

ANP Atrial Natriuretic Peptide is released by

atrial cells in response to stretch (if blood pressure is high)

ANP Atrial Natriuretic Peptide decreases

blood pressure and blood volume

ANP Atrial Natriuretic Peptide decreases the production of

ADH, renin, and aldosterone

ANP Atrial Natriuretic Peptide increases the excretion of

sodium and water

ANP Atrial Natriuretic Peptide promotes

vasodilation

Along with sodium, what produces the RMP and AP of nerve and muscle cells

potassium

RMP (resting membrane potential)

a difference in electrical potential across the membrane of a nerve cell during an inactive period

AP (action potential)

Found in nervous and muscle tissue

Will use RMP to generate an electrical signal (AP) that will travel down a neuron

The most abundant cation of the ICF

potassium

Potassium (K+) balance is controlled by what organ

kidney

What hormone regulates potassium secretion

aldosterone

Potassium is part of the body's _______ system

buffer

A shift in H+ concentration in and out of cells induce corresponding shifts in

potassium (K+) in the opposite direction to maintain cation balance (buffer system)

Sodium is reabsorbed at collecting ducts and never excreted, while ______can be excreted at ducts

K (potassium)

What hormone regulates calcium?

parathyroid hormone (PTH)

Calcium role

neuromuscular excitability, blood clotting, cell membrane permeability, skeleton strength

Hypocalcemia

overexcitation of nerves and muscles, causes muscle tetany

muscle tetany

Spasms or rapid contractions caused by deficiency of calcium in blood

Hypercalcemia

muscle weakness, depressed reflexes, and cardiac arrhythmia

hypercalcemia vs hypocalcemia

excessive calcium in the blood vs deficient calcium in the blood

Calcium balance is controlled by _______ and ________

parathyroid hormone (PTH) and calcitonin

The major anion in the ECF

Cl- (chloride)

Role of Cl- (chloride)

helps maintain osmotic pressure of the blood, follows Na+ ions out of filtrate

An increase in ECF solute content causes

water to move out of the cell

explanation: Water follows high concentration of solutes

ANP

Atrial natriuertic peptide, increases water and sodium removal by the kidney (to decrease blood pressure).

You would expect blood levels of ANP to increase when

blood pressure increases, there is an increase in preload, and the walls of the atria are stretched

Preload

volume of blood in ventricles at end of diastole (precontraction pressure)

If blood pressure rises, what works to reduce it

Atrial Natriuretic peptide

Blood and tissue fluid normally have a pH between

7.35 to 7.45

Alkalosis

The buildup of excess base (lack of acids) in the body fluids, arterial blood pH above 7.45

Acidosis

excessive acidity of body fluids, arterial blood pH less than 7.35

Why does the body use buffer systems

to regulate the pH range and create an acid-base balance

pH means

power of hydrogen

Chemical buffer systems regulate

concentration of hydrogen ions first, are the first line of defense

Brain stem respiratory centers regulate

concentration of hydrogen ions second, acts within 1 to 3 minutes

Renal mechanisms regulate

concentration of hydrogen ions third and are the most potent, but require hours to days to effect pH changes