Lecture 3

Question 1

Fluid Intake Methods (3)

Answer 1

Metabolism - 10%
Food - 30%
Beverages - 60%

Question 2

Fluid Excretion Methods (4)

Answer 2

Feces - 4%
Sweat - 8%
Insensible Loss (Skin/Lungs) - 28%
Urine - 60%

Question 3

Triggers of Thirst (3)

Answer 3

1. Osmolarity
2. Volumetric
3. Angiotensin

Question 4

Osmolarity

Answer 4

Increased osmolarity from increased salt intake or decreased water volume triggers thirst response to try and fix the osmolarity of the blood.

Question 5

Volumetric

Answer 5

Decreased blood volume. Limited vascular restriction assistance. Need to increase intake and volume to offset the imbalance.

Question 6

Receptors to Detect Volumetric Imbalance

Answer 6

1. Low Pressure - baroreceptors in great veins, pulmonary vessels, and right atrium
2. High Pressure - baroreceptors in carotid sinus & aorta

Question 7

Angiotensin II Effects (5)

Answer 7

1. Thirst
2. More Water/Na+ absorption
3. Releases aldosterone
4. Vasoconstriction
5. ADH Secretion

Question 8

ADH Mechanism

Answer 8

Released by hypothalamus. Causes blood vessels to constrict and makes the collecting duct highly permeable to water to allow for lots of its reabsorption (doesn’t affect salt). Increases blood pressure and volume

Question 9

Aldosterone Mechanism

Answer 9

Acts on Na+/K+ pumps and increases their numbers in the kidneys. Pulls more sodium out of cell and increases amount of sodium in blood stream that causes water to follow it.

Question 10

Other ways to Intake Fluids (3)

Answer 10

1. IV
2. Gastric Tubes
3. Subcutaneously

Question 11

Body Fluid Compartments (3)

Answer 11

1. Vascular - blood vessels
2. Interstitial - in between vessels and cells
3. Intracellular - inside cells

Question 12

Fluid Forces (3)

Answer 12

1. Hydrostatic pressure - pushes fluid from inside the vessel out, decreases in pressure the farther away from the heart you get
2. Osmotic pressure - pushes fluid from outside the vessel in, constant throughout the body
   (net out closer to the heart, net in farther away)
3. Osmosis - driven by osmolarity, water moves towards hypertonic solutions

Question 13

Types of Fluid Imbalances (2)

Answer 13

1. Extracellular fluid

2. Body fluid concentrations

Question 14

Extracellular Imbalances (aka Saline Imbalances)

Answer 14

Impacts vascular and interstitial fluid volumes. Caused by too little or too much fluid. Concentration is right, just not the right volume.

Question 15

How do extracellular imbalances occur? (too little volume) (5)

Answer 15

1. Loss of salt water from the body (vomiting, diarrhea)
2. Excess renal excretion of salt & water (excess use of diuretics or aldosterone deficiency)
3. Hemorrhaging
4. Excessive sweating (diaphoresis)
5. Burns

Question 16

Thiazide Mechanism

Answer 16

Block Na+/Cl- transporter in distal tubule, preventing Na+ absorption, decreasing blood volume due to Na+ and H2O excretion

Question 17

Potassium-Sparing Diuretic Types

Answer 17

1. Sodium Channel Inhibitors

2. Mineral Corticoid receptor antagonist

Question 18

Sodium Channel Inhibitors Mechanism

Answer 18

Block sodium channels in collecting duct, decreases Na+ reabsorption and subsequent excretion of potassium. Water follows the Na+

Question 19

Mineral Corticoid Receptor Antagonist Mechanism

Answer 19

Competes with aldosterone receptor, decreases sodium reabsorption of sodium channels

Question 20

Loop Diuretics Mechanism

Answer 20

Block Na+/K+/2Cl- transport in thick, ascending loop of Henle preventing Na+ absorption. Leads to PROFOUND Na+ & H2O loss

Question 21

Volume Deficient Clinical Manifestations (6)

Answer 21

1. Sudden weight loss (2+ lbs in 24 hours)
2. Flat neck veins (lying down, no JVD)
3. Decreased Skin Turgor
4. Sunken eyeballs
5. Deeper longitudinal furrows in tongue
6. Sunken fontanels in infants

Question 22

Causes of Excess Volume (4)

Answer 22

Excessive intake or retention of salt water

1. Excessive IV infusion
2. Excessive aldosterone
3. Corticosteroid therapy
4. Cushing Disease

Question 23

Excess Volume Clinical Manifestations (5)

Answer 23

1. Sudden weight gain
2. Circulatory overload - bounding pulse, hypertension, JVD when upright
3. Edema - swelling
4. Bulging fontanel in infants
5. Dyspnea and orthopnea

Question 24

Hyponatremia

Answer 24

“Hypotonic Syndrome,” gain more water than salt, causes cells to swell with fluid and risk bursting.

Question 25

Hyponatremia Causes (6)

Answer 25

1. Water Intoxication 2. Excessive ADH 3. Psychogenic Polydipsia- compulsive drinking of water from psychogenic drugs like ecstasy 4. Forced Water consumption - hazing 5. Excessive beer intoxication - needs to be a LOT, VERY QUICKLY to overcome the ADH inhibition that occurs when drinking alcohol 6. Near drowning in fresh water

Question 26

Hyponatremia Clinical Manifestations (7)

Answer 26

1. Neurological - brain swelling 2. Nausea 3. Vomiting 4. Headache 5. Confusion 6. Seizures 7. Coma

Question 27

Hypernatremia

Answer 27

"Hypertonic Syndrome," water deficit. Can occur from gaining more salt than water or losing more water than salt.

Question 28

Hypernatremia Causes (5)

Answer 28

1. Limited access to water 2. Hypertonic IV solution 3. Near drowning in salt water 4. Diabetes insipidus - low ADH 5. Prolonged diarrhea and/or vomiting without intaking water

Question 29

Hypernatremia Clinical Manifestations

Answer 29

Similar to hyponatremia manifestations except causes brain cells to shrivel and shrink instead of swell.

Question 30

Hypokalemia

Answer 30

Decrease in interstitial potassium levels

Question 31

Hypokalemia Causes

Answer 31

Many etiologies but diuretics can be a potential cause

Question 32

Hypokalemia's Effect on Cells

Answer 32

- Makes intracellular charges mores negative - Hyperpolarized muscle cells (cardiac, skeletal, heart) - Requires stronger signals to depolarize

Question 33

Hypokalemia Clinical Manifestations (5)

Answer 33

1. Skeletal & muscle weakness 2. Flaccid paralysis 3. Respiratory paralysis 4. Cardiac dysfunction 5. Gastrointestinal problems

Question 34

Liquorice Poisoning

Answer 34

Blocks an enzyme that converts cortisol to cortisone. Stimulates aldosterone receptors and leads to sodium retention (hypertension) and potassium excretion (hypokalemia)

Question 35

Hyperkalemia

Answer 35

Increase in interstitial potassium levels

Question 36

Hyperkalemia Causes

Answer 36

Many etiologies including potassium injections, blood transfusions that are potassium rich, or diseases like cancer releasing excess potassium

Question 37

Hyperkalemia's Effect on Cells

Answer 37

Membranes become depolarized and more positive than negative.

Question 38

Hyperkalemia Clinical Manifestations

Answer 38

Similar to Hypokalemia

Question 39

Hypocalcemia

Answer 39

Free calcium ions at below normal serum levels

Question 40

Forms of Calcium in Plasma (3)

Answer 40

1. Ions bound to proteins (albumin) 2. Ions bound to small organic ions (citrate) 3. Free ions

Question 41

Hypocalcemia Etiologies (5 commom)

Answer 41

1. Steatorrhea due to low bile 2. Vitamin D deficiency 3. Massive transfusion 4. Hypoparathyroid 5. Excess phosphate

Question 42

Calcium Pathophysiology

Answer 42

Key for neuromuscular junction response and muscle contractions. The amount of calcium directly correlates with the amount of sodium needed to fire an action potential (less calcium : less sodium needed, more calcium : more sodium needed)

Question 43

Hypocalcemia Clinical Manifestations (6)

Answer 43

- Increased neuromuscular excitability - Muscle twitching & cramping - Tetany - Positive Trousseau - Positive Chvostek - muscles twitching/convulsing when touching muscle on cheek - Cardiac problems

Question 44

Hypercalcemia

Answer 44

Free calcium ions at higher than normal serum levels

Question 45

Hypercalcemia Causes (3)

Answer 45

- Etiologies causing excessive intake and absorption - Shift in storage (hyperparathyroidism, bone cancers) - Decreased excretion

Question 46

Hypercalcemia Clinical Manifestations (4)

Answer 46

* *Need more sodium to fire an action potential due to increased levels of calcium** 1. Decreased muscular excitability 2. Gastrointestinal abnormalities 3. Muscle weakness 4. Cardiac problems

Question 47

Magnesium's Effect on Muscle Contraction

Answer 47

Magnesium depresses acetylcholine release and effects the amount of neuromuscular excitability

Question 48

Hypomagnesemia

Answer 48

Too much acetylcholine released and causes increased neuromuscular excitability.

Question 49

Hypermagnesemia

Answer 49

Too little acetylcholine released and causes decreased neuromuscular excitability.