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Anatomy & Physiology Review I > Chapter 27 - Fluid, Electrolytes, and Acid-Base Homeostasis > Flashcards

Chapter 27 - Fluid, Electrolytes, and Acid-Base Homeostasis Flashcards

1
Q

What is Body Fluids?

A

Between 55-65% of total body mass
2/3 inside cells
1/3 outside cells

1- Intracellular Fluid (ICF):
Cytosol

2- Extracellular Fluid (ECF):
Interstitial Fluid 80%
Blood Plasma 20%

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2
Q

What divides Body Fluids and how do they Interact?

A

Plasma Membrane:
Separates ICF from Interstitial Fluid

Blood Vessel Walls:
Divide the Interstitial Fluid from Blood Plasma

Capillary Walls:
Thin enough to allow exchange of water and solutes between Blood Plasma and Interstitial Fluid

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3
Q

What allows Continuous Exchange of Water and Solutes among Body Fluid Compartments?

A

Filtration, Reabsorption, Diffusion, and Osmosis:
Allow continuous exchange of water and solutes among body fluid compartments:

1- Balance of inorganic compounds that dissociate into ions (Electrolytes) is closely related to fluid balance

2- Body gains water by ingestion and metabolic synthesis

3- Body loses water via urination, perspiration, exhalation, and in feces

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4
Q

What determines Volume of Metabolic Water Formed?

A

Level of Aerobic Respiration determines volume of metabolic water formed:

Amount of water formed is directly proportional to the amount of ATP produced

When water loss is greater than water gain, dehydration occurs, leading to increased thirst

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5
Q

What is the Thirst Response?

A

1- Increased blood osmolarity:
Stimulates osmoreceptors in Hypothalamus

2- Decrease blood volume:
Decreased activity of Atrial Volume Receptors

3- Decrease BP:
Decreased activity of Baroreceptors in blood vessels
Increase release of Renin from Kidneys -> increased Angiotensin II formed

4- Dry Mouth

5- All of that stimulates Thirst Center in Hypothalamus

6- Increase Thirst

7- Increase water intake

8- Increased water intake:
Decrease blood osmolarity
Increase BP and Blood Volume
Relieves mouth dryness

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6
Q

What is Excess Body Water Elimination?

A

Elimination of excess body water occurs through urine production
Amount of Urinary salt loss is main factor determining body fluid volume

The 2 Main Solutes in urine:
1- Na+
2- Cl-

Wherever solutes go, water follows

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7
Q

What are the 3 Major Hormones that Control Renal Na+ and Cl-?

A

1- Angiotensin II
2- Aldosterone
3- Atrial Natriuretic Peptide (ANP)

The major hormone that regulates water loss is ADH

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8
Q

What is Regulation of Water and Solute Loss by ADH?

A

1- Increased blood osmolarity:
Stimulates osmoreceptors in Hypothalamus

2- Decrease blood volume:
Decreased activity of Atrial Volume Receptors

3- Decrease BP:
Decreased activity of Baroreceptors in blood vessels

4- Other factors such as pain, nausea, and stress

5- All of these increase synthesis of ADH by Neurosecretory Cells in Hypothalamus

6- Increased release of ADH from Posterior Pituitary Gland

7- Late DCT and CD of Kidneys become more permeable to water, which increases water reabsorption

8- The increase of water reabsorption in turn:
Decrease blood osmolarity
Increase BP and Blood Volume

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9
Q

What is Regulation of Water and Solute Loss by Aldosterone?

A

1- Decrease BP and Na+ deficiency in Plasma

2- Increased release of Renin by Kidneys

3- Increased Aldosterone formation

4- Aldosterone:
Increase Na+ reabsorption in late DCT and CD of Kidneys
Water reabsorption accompanies Na+ reabsorption via Osmosis because ADH is also released when there is decrease in BP

5- Increased Na+ reabsorption relives the Na+ deficiency in Plasma
The accompanying water reabsorption increase BP and Blood Volume

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10
Q

What is Regulation of Water and Solute Loss by ANP?

A

1- Increased Blood Volume

2- Increased stretch of Atria

3- Release of ANP

4- Increase excretion of Na+ into urine (Natriuresis)
Water excretion into urine also increases due to Osmosis

5- Increase water in excretion causes a decrease in BP and Blood Volume

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11
Q

What is Mechanism and Effect of Thirst Center in Hypothalamus?

A

1- Mechanism:
Stimulate desire to drink fluids

2- Effect:
Water gained if thirst is quenched

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12
Q

What is Mechanism and Effect of ADH?

A

1- Mechanism:
Promotes insertion of Aquaporin-2 into Apical membranes of Principal Cells in CD of Kidneys
As a result, water permeability of these cells increase and more water is reabsorbed

2- Effect:
Reduce water loss in urine

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13
Q

What is Mechanism and Effect of Aldosterone?

A

1- Mechanism:
By promoting urinary reabsorption of Na+ increases water reabsorption via Osmosis

2- Effect:
Reduce water loss in urine

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14
Q

What is Mechanism and Effect of ANP?

A

1- Mechanism:
Promotes Natriuresis
Elevated urinary excretion of Na+
Accompanied by water

2- Effect:
Increase water loss in urine

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15
Q

What is Water Movement Between Body Fluid Compartments?

A

When the ECF is Isotonic to the cells of body, they do not shrink or swell

However, changes in osmolarity of ECF (as with dehydration or over-hydration) can cause the cells of body to shrink or swell

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16
Q

What is Water Intoxication?

A

Water Intoxication:
Occurs when excess body water causes cells to swell dangerously
This may occur when a person consumes water faster than the Kidneys can excrete it

1- Excessive blood loss, sweating, vomiting, or diarrhea coupled with intake of plain water

2- Decrease Na+ concentration (Hyponatremia) of ECF

3- Decreased osmolarity of ECF

4- Osmosis of water from ECF into ICF

5- Water Intoxication (Cells swell)

6- Mental confusion, seizures, coma, and possible death

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17
Q

What is Electrolytes in Body Fluids?

A

Ions formed when Electrolytes dissociate and dissolve:
1- Control osmosis of water between fluid compartments
2- Help maintain the acid-base balance
3- Carry electrical current
4- Serve as Cofactors

Blood Plasma, Interstitial Fluids, and ICF have different concentrations of Electrolytes and protein ions

Blood Plasma contains more protein ions
Interstitial Fluid contains only a few

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18
Q

What is Na+?

A

Most abundant Cation (+) in ECF

Used for:
Impulse transmission
Muscle contraction
Fluid and Electrolyte balance

Its level controlled by:
Aldosterone
ADH
ANP

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19
Q

What is Cl-?

A

Major ECF Anion (-)

Helps regulate osmotic pressure between compartments
Forms HCL in Stomach

Regulated by:
Aldosterone

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20
Q

What is K+?

A

Most abundant Cation (+) in ICF

Involved in:
Fluid volume
Impulse conduction
Muscle contraction
Regulating pH

Regulated by:
Mineralocorticoids (mainly Aldosterone)

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21
Q

What is HCO3- (Bicarbonate)?

A

Important Plasma ion

Major member of Plasma’s acid-base buffer system

Kidneys reabsorb or secrete it for final acid-base balance

22
Q

What is Ca2+?

A

Most abundant mineral in body

Structural component of Bones and Teeth

Used for:
Blood coagulation
NT release
Muscle tone
Excitability of nerves and muscles

Regulated by:
PTH

23
Q

What is Ca3(PO4)2?

A

Phosphate occurs as Calcium Phosphate Salt

Used in:
Buffer system

Regulated by:
PTH
Calcitriol

24
Q

What is Mg2+?

A

ICF Cation (+)

Activates enzymes involved in carb and protein metabolism

Used in:
Myocardial function
Transmission in CNS
Operation of Na+ Pump

25
What is Hyponatremia?
Na+ deficiency 1- Cause: Low Na+ intake Increased Na+ loss through vomiting, diarrhea, Aldosterone deficiency, or taking certain Diuretics Excessive water intake 2- Signs/Symptoms: Muscular weakness Dizziness Headache Hypotension Tachycardia Shock Mental confusion Stupor Coma
26
What is Hypernatremia?
Na+ Excess 1- Cause: Dehydration, water deprivation Excessive Na+ in diet or IV fluids Causes Hypertonicity of ECF which pulls water out of cells to ECF causing cellular dehydration 2- Signs/Symptoms: Intense thirst Hypertension Edema Agitation Convulsions
27
What is Hypochloremia?
Cl- Deficiency 1- Cause: Excessive vomiting Overhydration Aldosterone deficiency CHF Therapy with certain Diuretics like Furosemide (Lasix) 2- Signs/Symptoms: Muscle spasms Metabolic Alkalosis Shallow respirations Hypotension Tetany
28
What is Hyperchloremia?
Cl- Excess 1- Cause: Dehydration from water loss or water deprivation Excessive Cl- intake Severe Renal failure Hyperaldosteronism 2- Signs/Symptoms: Lethargy Weakness Metabolic Acidosis Rapid deep breathing
29
What is Hypokalemia?
K+ Deficiency 1- Cause: Excessive vomiting/diarrhea Decreased K+ intake Hyperaldosteronism Kidney disease Therapy with some Diuretics 2- Signs/Symptoms: Muscle fatigue Flaccid paralysis Mental confusion Increased urine output Shallow respirations Changes in EKG including Flattening of T Wave
30
What is Hyerkalemia?
K+ Excess 1- Cause: Excessive K+ intake Renal failure Aldosterone deficiency Crushing injuries to body tissues Transfusion of hemolyzed blood 2- Signs/Symptoms: Irritability Nausea Vomiting Diarrhea Muscular weakness Can cause death by inducing V-Fib
31
What is Hypocalcemia?
Ca2+ Deficiency 1- Cause: Increased Ca2+ loss Reduced Ca2+ intake Elevated Phosphate levels Hyperparathyroidism 2- Signs/Symptoms: Numbness and tingling of fingers Hyperactive reflexes Muscle cramps, Tetany, and Convulsion Bone fractures Spasms of Laryngeal muscles that can cause death by Asphyxiation
32
What is Hypercalcemia?
Ca2+ Excess 1- Cause: Hyperparathyroidism Some cancers Excessive intake of Vitamin D Paget's Disease of Bone 2- Signs/Symptoms: Lethargy Weakness Anorexia Nausea Vomiting Polyuria Itching Bone pain Depression Confusion Paresthesia Stupor Coma
33
What is Hypophosphatemia?
Phosphate Deficiency 1- Cause: Increase urinary loss Increased Intestinal absorption Increased utilization 2- Signs/Symptoms: Confusion Seizures Coma Chest and muscle pain Numbness and tingling of fingers Decreased coordination Memory loss Lethargy
34
What is Hyperphosphatemia?
Phosphate Excess 1- Cause: Kidneys fail to excrete Phosphate (Renal failure) Increased intake of Phosphate Destruction of body cells which releases phosphate into blood 2- Signs/Symptoms: Anorexia Nausea Vomiting Muscular weakness Hyperactive reflexes Tetany Tachycardia
35
What is Hypomagnesemia?
Mg2+ Deficiency 1- Cause: Inadequate intake or excessive loss in urine and feces Alcoholism Malnutrition Diabetes Mellitus Diuretic therapy 2- Signs/Symptoms: Weakness Irritability Tetany Delirium Convulsions Confusion Anorexia Nausea Vomiting Paresthesia Cardiac Arrhythmias
36
What is Hypermagnesemia?
Mg2+ Excess 1- Cause: Renal failure Increased Mg2+ intake (like Mg2+ antiacids) Aldosterone deficiency Hyperthyroidism 2- Signs/Symptoms: Hypotension Muscular weakness or paralysis Nausea Vomiting Altered mental functioning
37
What is Acid-Base Balance?
pH of Arterial Blood ranges from 7.35-7.45 Mechanisms that maintain this range: 1- Buffer Systems 2- Exhalation of CO2 3- Kidney excretion of H+
38
What is a Buffer System?
Most consist of a Weak Acid, and its salt, which function as a Weak Base Prevent drastic changes in body fluid pH
39
What is Protein Buffer System?
Protein Buffer System: Most abundant in ICF and Blood Plasma 1- When pH rises: COOH group dissociates to act like an Acid COOH -----> COO- + H+ 2- When pH falls: The free amino group dissociates to act like a Base NH2 + H+ -----> NH3+
40
What is Hemoglobin in RBC as Buffer?
Hg in RBC acts as a Buffer: H2O + CO2 -----> H2CO3 (carbonic acid) H2CO3 (carbonic acid) -----> H+ + HCO3- (bicarbonate) Hb-O2 (oxyhemoglobin) + H+ -----> Hb-H (reduced Hg) + O2
41
What is Carbonic Acid-Bicarbonate Buffer System?
Important regulator of blood pH Most abundant buffer in ECF Based on the: 1- Bicarbonate ion (HCO3-) which acts as a Weak Base 2- Carbonic Acid (H2CO3) which acts as a Weak Acid If pH falls: HCO3- removes excess H+ H+ + HCO3- -----> H2CO3 If pH rises: H2CO3 can provide H+ H2CO3 -----> H+ + HCO3-
42
What is Phosphate Buffer System?
Important buffer in ICF and urine Acts similarly to Carbonic Acid-Bicarbonate Buffer System: 1- Dihydrogen Phosphate (H2PO4-) acts a Weak Acid 2- Monohydrate Phosphate (HPO42-) acts as Weak Base OH- (Hydroxide ion) + H2PO4- -----> H2O + HPO42- H+ + HPO42- -----> H2PO4-
43
What is Exhalation of CO2 Buffer System?
Exhalation of CO2: Mixes CO2 with H2O in blood to form Carbonic Acid (H2CO3) Exhaling CO2 leads to less acid production and a rise in pH Whereas retaining CO2 leads to more acid production and a drop in pH CO2 + H2O <-----> H2CO3 <-----> H+ + HCO3-
44
What is Negative Feedback Loop of Decreased Blood pH?
1- Decrease blood pH (more H+ concentration) 2- Central Chemoreceptors in Medulla Oblongata and Peripheral Chemoreceptors in Aortic and Carotid Bodies send nerve impulses 3- Dorsal Respiratory Group (DRG) in Medulla Oblongata sends nerve impulses 4- Diaphragm contracts more forcefully and frequently, so more CO2 is exhaled 5- As less H2CO3 forms, and fewer H+ are present, Blood pH increases (and H+ concentration decreases)
45
What is Kidney Excretion of H+?
Excreting H+ in urine removes nonvolatile acids PCT and CD of Kidneys secrete H+ into Tubular fluid then Urine Reabsorb HCO3- so it's not lost in Urine Some H+ secreted into Tubular Fluid of CD is buffered by HPO42- and NH3 The buffers are excreted in urine
46
What is Acidosis?
Blood pH < 7.35
47
What is Alkalosis?
Blood pH > 7.45
48
What is Respiratory Acidosis?
Blood pH drops due to: Retention of CO2 which leads to excess H2CO3 (carbonic acid) (and decrease pH) 1- Causes: Hypoventilation due to Emphysema Pulmonary Edema Trauma to Respiratory Center Airways obstructions Dysfunction of muscles of respiration 2- Compensatory Mechanisms: Renal: Increase excretion of H+ Increased reabsorption of HCO3- If complete then pH will be normal but pCO2 high
49
What is Respiratory Alkalosis?
Blood pH rises due to: Excessive loss of CO2 as in Hyperventilation (and increase pH) 1- Causes: Hyperventilation due to oxygen deficiency Pulmonary disease CVA Severe accident 2- Compensatory Mechanisms: Renal: Decreased excretion of H+ Decreased reabsorption of HCO3- If complete then pH normal but pCO2 low
50
What is Metabolic Acidosis?
Arterial Blood levels of HCO3- fall (and decreased pH) 1- Causes: Loss of HCO3- due to diarrhea Accumulation of acid (ketosis) Renal Dysfunction 2- Compensatory Mechanisms: Respiratory: Hypoventilation slows loss of CO2 If complete pH will be normal but HCO3- high
51
What is Metabolic Alkalosis?
Arterial Blood levels of HCO3- rise (and increased pH) 1- Causes: Loss of acid due to vomiting Gastric suctioning Use of certain Diuretics Excessive intake of Alkaline drugs 2- Compensatory Mechanisms: Respiratory: Hypoventilation slows CO2 loss If complete pH will be normal but HCO3- high
52
How does Aging affect Fluid, Electrolytes, and Acid-Base Balance?
Significant diseases exist between adults and infants with respect to fluid distribution, regulation of fluid and electrolyte balance, and acid-base homeostasis Factors that influence distribution: 1- Metabolic Rate 2- Functional Development of Kidneys 3- Body surface area 4- Breathing Rate 5- Ion concentrations Older adults often have impaired ability to maintain balance Often suffer from dehydration, Hypernatremia, Hypokalemia, and Acidosis

Anatomy & Physiology Review I (30 decks)

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