Bio 322 Exam 1 Study Guide Topic 1C

Total Body Water

• body fluids compose 60% of total body weight

• 2/3rd of the body H2O is in the ICF

• 1/3rd of the body H2O is in the ECF

• affected by gender and age (decrease as we age)

Interstitial fluid and plasma

nearly identical because they care constantly mixing

Edema

• excess retention of interstitial fluid resulting in swelling

• can be anywhere but most noticeable in extremeities 

• localized - due to trauma or around an organ

• generalized - uniform distribution of fluid 

Capillary Hydrostatic Pressure (CHP)

pushes fluid out of capillary (BP)

Capillary Osmotic Pressure (COP)

pulls fluid into capillary (albumin)

Interstitial Fluid Hydrostatic Pressure (IFHP)

pushes fluid into capillary

Interstitial Fluid Osmotic Pressure (IFOP)

pulls fluid into interstitial space

Causes of Edema

• increased capillary filtration

• decreased capillary reabsorption

• increased capillary permeability (caused by histamine, allows leakage)

• lymphatic obstruction

Net filtration

(CHP + IFOP) - (IFHP + COP)

Consequences of Edema

• tissue necrosis

  • oxygen delivery and waste removal imparied

• pulmonary edem

  • hypoxia

• cerebral edema

  • headaches, nausea, seizures, coma, death 

• circulatory shock

  • excess fluid in tissue spaces causes low blood volume and low BP

Left Heart Failure

• inability of left side to pump into systemic circulation

• congestion in lungs

• pulmonary edema

Right Heart Failure

• inability of right side to adequately pump venous blood into pulmonary circulation

• congestion in the body 

• pitting edema, ascites 

Ascites

• accumulation of fluid in peritoneal space

• MCC: liver cirrhosis → portal hypertension

• pathophysiology - decrease albumin, decreased cop, edema 

Lymphedema

• localized edema 

• accumulation of lymphatic fluid

• often due to lymph node removal 

Decreased water loss leads to

increased blood volume

Anti-diuretic hormone

decrease water loss due to H2O reabsorption in the kidney

Aldosterone

• renal reabsorb sodium (H2O follow)

• excrete potassium

ANP and BNP stimulate

renal elimination of Sodium (H2O follows Na+)

What triggers release of ANP and BNP

increase blood volume/blood pressure

What effect does the release of ANP and BNP have

• decrease sodium

• decrease blood volume

• decrease blood pressure

Hypovolemia

decrease blood volume

hypervolemia

increase blood volume

Kidney releases renin when it detects

• decreased blood volume

• decreased blood pressure

• decrease sodium

effect of kidney releasing renin

• increase ADH (vasopressin)

• increased thirst → increased blood volume

• sympathetic nervous system 

  • vasoconstriction → increased blood pressure

  • increase aldosterone

ADH / Vasopressin

• made in hypothalamus

• stored in posterior pituitary

• targets DCT and CD in the kidney 

• reabsorbs H2O back into circulation

What triggers release of ADH

• increase osmolarity

• decrease BV/ decreased BP

Hypernatremia 

• increase sodium

• decreased water intake

• increased water loss

• diuretics, vomiting, diarrhea

• sweating, dehydration

• hyper secretion of aldosterone

• Diabetes insipidus

Hyponatremia

• decrease sodium

• increased water intake

• water intoxication

• diuretics, vomiting, diarrhea

• SIADH

• kidney, heart, liver dysfunction

Syndrome of Inappropriate ADH Secretion (SIADH)

• increase ADH

• hyponatremia

• causes: idiopathic, brain trauma, paraneoplastic syndrome, Medication SE

• pathophysiology

  • increased H2O Reabsorption → decreased sodium

  • decreased serum osmolarity 

  • increased urine osmolarity 

  • decreased urine volume 

• “Water intoxication”

Paraneoplastic Syndrome

the consequence of cancer in the body, but unlike mass effect, is not due to the local presence of cancer cells

• most common types

  • humoral hypercalcemia of malignancy in squamous cell carcinoma 

  • syndrome of inappropriate antidiuretic hormone in small cell lung cancer

Diabetes Insipidus

insufficiency of ADH

Cause of Neurogenic Diabetes Insipidus

• absence of ADH

• pituitary problem such as brain tumor, hypophysectomy, aneurysm, thrombus, infection

• result of TBI

Cause of Nephrogenic diabetes insipidus

• inadequate response of renal tubules to ADH

• Pyelonephritis, PKD, amyloidosis

• Meds - Lithium, Colchicine, Amphotericitin B, loop diuretics, general anesthetics

Gestational Diabetes Insipidus

• increase levels of vasopressinase 

• ADH gets broken down

• rare and usually no treatment necessary

Signs and Symptoms of Diabetes Insipidus

• excessive urination and thirst 

  • polyuria and polydipsia

• excretion of large volume dilute urine, dehydration → 8-12 L/day vs 1-2 L/day (normal)

Testing for Diabetes Insipidus

• increased serum osmolarity vs decreased urine osmolarity

• plasma ADH levels 

• CT scan 

Dehydration

• s/s : hypotension and tachycardia 

• diagnosis

  • decreased skin turgor

  • decreased urine output

  • increased urine osmolarity 

  • blood 

    • increased HCT

    • increased serum osmolarity 

    • increased BUN: Cr ration

• treatment 

  • PO rehydration

  • IV rehydration

Sodium

• major cation outside of the cell (90%)

• 136-145 mEq/L

• maintains ECF osmotic balance - water follows salt 

• function

  • maintain tonicity of ECF

  • facilitate nerve conduction and glandular secretions

• Organs and hormones involved 

  • kidney 

  • aldosterone, ANP/BNP

• most often goes hand in hand with chloride 

Osmolality 

concentration of stuff in the blood 

Hypertonic solution

• concentrated blood

• Na: H2O ratio is high 

• hypernatremia 

• decreased water intake increased water loss

Hypotonic Solution

• dilute blood 

• Na : H2O ratio is low 

• hyponatremia 

• increased water intake or decreased water loss

• SIADH

signs and symptoms of hyponatremia

• headache, lethargy 

• N/;V

• confusion, disorientation

• seizures, come

• muscle weakness, cramps

• hyporeflexia

signs and symptoms of hypernatremia

• headache, restlessness

• N/V, thirsty, tachycardia

• confusion, disorientation

• seizures, come

• muscle twitching, spasms

• hyperreflexia

Potassium (K+)

• major cation inside of the cell (98%)

• greatest contributor to intracellular osmosis and cell volume

• plays a role in blood pH by affecting the plasma concentration 

Hypokalemia

• reduced intake of potassium

• increased entry of potassium into cells

• alkalosis

• increased entry of body potassium

• diarrhea, vomiting 

Hyperkalemia

• increased intake of potassium

• acidosis 

• increased exit of potassium from cells 

• decreased renal excretion of potassium

Hypokalemia s/s and EKG

• muscle weakness, cramps

• depressed/flattened t waves

• prominent U wave

Hyperkalemia s/s and EKG

• muscle weakness, spasticity 

• wide QRS w/ tall peaked T waves

Calcitriol

• activated in the kidney 

• increased Ca2+ absorption in GI

• increased Ca2+ reabsorption in kidney 

Hypocalcemia

• parathyroid hormone 

• easier for Na+ to enter the cell

• increased excitability 

• hyperreflexia

• convulsions/seizures

• Long QT interval

Hypercalcemia

• hyperparathyroidism

• short ST segment 

• decrease Na+ entry into cell

• decreased excitability

Acidosis

• hyperkalemia

• hypercalcemia 

• decreased excitability of CNS

Alkalosis

• over excitability of the CNS

• hypokalemia

• hypocalcemia