BIO Chapter 27 - Lecture notes 27 PDF

Preview

Summary

notes are created based off study guide for the course. BIO 235 course ...

Description

chapter 27

17-02-11 1:20 PM

Compare the location of intracellular fluid (ICF) and extracellular fluid (ECF), and describe the various fluid compartments of the body. fluid compartments and fluid balance •

intracellular fluid (ICF) or cytosol o

Fluid within the cells

•

extracellular fluid (ECF) : fluid outside the cell

•

interstitial fluid : ECF that occupies the microscopic apc b/w tissue cells

•

plasma : liquid portion of the blood

•

fluid balance : body is in fluid balance when the reuired amount of water and solute are present and are correctly proportioned among various compartment.

•

electrolytes :inorganic compounds that dissociate into ions, fluid balance is closely related to it.

Describe the sources of water and solute loss and gain, and explain how each is regulated. sources of body water gain and loss •

Body can gain water by ingestion and by metabolic syntheses , main source are ingested liquids, moist food absorbed from GI tract

•

Other source is metabolic water that is produced in the body mainly when electrons are accepted by oxygen during aerobic respirations

•

Daily water gain is about 2500ml

•

Water loss is through urine, skin evaporates, lungs exhale and the GI tract eliminates about 100ml in feces

regulation of water gain •

volume of metabolic water formed in the body depends entirely on the level of aerobic respiration, which reflects the demand for ATP in body cells. More ATP= MORE water

•

dehydration: when water loss is greater than water gain

regulation of water and solute loss—hormones •

•

Angiotensin II: o

Reduced loss of water in urine

o

stimulates secretion of aldosterone

Aldosterone: o

Reduced loss of water in urine

o

By promoting urinary reabsorption of Na+ and Cl−, increases water reabsorption via osmosis.

•

Atrial natriuretic peptide (ANP) o

Increase loss of water in urine

o

Promotes natriuresis, elevated urinary excretion of Na+ (and Cl−), accompanied by water.

•

Antidiuretic hormone (ADH), also known as vasopressin o

Reduced loss of water in urine

o

Promotes insertion of water-channel proteins (aquaporin-2) into apical membranes of principal cells in collecting ducts of kidneys. As a result, water permeability of these cells increases and more water is reabsorbed.

Explain how fluids move between compartments. A. movement of water between fluid compartments •

changes in osmolality of interstitial fluid causes fluid imbalance , changes is usually because of NA concentration

•

increase osmolality draws water out of the cell causing it to shrink

•

decrease osmolarity causes cell to swell

•

decrease in osmolarity occurs after drinking large amount of water , inhibits secretion of ADH

•

When a person drinks water faster than the kidney can excrete it, the result is water intoxication

•

water intoxication: a state in which excessive body water causes cells to swell dangerously. If the body water and Na+ lost during blood loss or excessive sweating, is replaced with just drinking water, the body fluid becomes more dilute, the Na concentration falls , which causes the osmolarity to fall

•

water entering the cells causes them to swell, which can lead to convulsion, coma and possibly death

Compare the electrolyte composition of plasma, interstitial fluid and intracellular fluid. •

ions formed when electrolytes dissolve and dissociate serve four general functions in the body.

•

Ions control the osmosis of water between fluid compartments

•

(2) Ions help maintain the acid–base balance required for normal cellular activities

•

(3) Ions carry electrical current, which allows production of action potentials and graded potentials

•

(4) Several ions serve as cofactors needed for optimal activity of enzymes.

electrolytes in body fluids •

plasma: contains many protein anion compared to interstitial fluid ( has a few anion)

•

only few plasma protein leak out of blood vessels into the interstitial fluid

•

diff protein concentration is largely responsible for the blood colloid osmotic pressure exerted by blood plasma

•

extracellular fluid, the most abundant cation is Na+, and the most abundant anion is Cl−

•

In intracellular fluid, the most abundant cation is K+, and the most abundant anions are proteins and phosphates (HPO42−)

Discuss the functions and explain how their concentrations are regulated. sodium

•

role in fluid and electrolyte balance because it accounts for almost half of the osmolarity of extracellular fluid (

•

The flow of Na+ through voltage-gated channels in the plasma membrane also is necessary for the generation and conduction of action potentials

•

Na+ level in the blood is controlled by aldosterone, antidiuretic hormone (ADH), and atrial natriuretic peptide (ANP).

•

Aldosterone increases renal reabsorption of Na+

•

In hyponatremia, ADH release ceases

•

In hypernatremia, ANP increases NA excretion

potassium •

in intracellular fluid

•

role in establishing the resting membrane potential and in the repolarization phase of action potentials in neurons and muscle fibers

•

helps maintain normal intracellular fluid volume

•

also regulates PH of body fluids

•

concentration regulated by aldosterone

•

K+ concentration is high, more aldosterone is secreted into the blood

•

when blood plasma K+ concentration is low, aldosterone secretion decreases and less K+ is excreted in urine.

bicarbonate •

concentration increases as blood flows through systemic capillaries

•

concentration decrease as blood flows through pulmonary capillaries, as carbon dioxide is exhaled.

•

helps maintain the correct balance of anions in extracellular fluid and intracellular fluid.

•

kidneys are the main regulators of blood HCO3− concentration.

•

cells of the renal tubule can either form HCO3− and release it into the blood when the blood level is low or excrete excess HCO3− in the urine when the level in blood is too high

calcium •

contributing to the hardness of bones and teeth

•

roles in blood clotting, neurotransmitter release, maintenance of muscle tone, and excitability of nervous and muscle tissue.

•

most important regulator of Ca2+ is parathyroid hormone (PTH)

•

calcitriol ( increases calcium absorption)

•

calcitonin lowers blood calcium level

phosphate •

structural component of bone and teeth

•

important buffer of H+

•

regulated by PTH and Calcitriol,

•

Fibroblast growth factor 23 ( decrease levels by excretion by the kidney and decreasing absorption by GI tract).

Compare the role of buffers, exhalation of carbon dioxide and kidney excretion of H+ in maintaining the pH of body fluids. acid-base balance •

actions of buffer systems

•

protein buffer system

•

carbonic acid-bicarbonate buffer system

•

phosphate buffer system

•

exhalation of carbon dioxide

•

kidney excretion of H+

7. Describe the various types of acid-base imbalances, their effects on the body and how they are treated acid-base imbalances •

normal PH is between 7.35-7.45

•

acidosis or academia: PH below 7.35

•

alkalosis or alkalemia : PH above 7.45

compensation •

the physiological response to an acid–base imbalance that acts to normalize arterial blood pH.

respiratory compensation •

form of compensation that brings blood Ph back toward normal range through the help of hyperventilation or hypoventilation

renal compensation •

changes in secretion of H+ and reabsorption of HCO3− by the kidney tubules— this can help reverse the change.

respiratory acidosis •

PCO2 in systemic arterial blood—above 45 mmHg.

•

inadequate exhalation of CO2 causes the blood pH to drop

•

caused by conditions include emphysema, pulmonary edema, injury to the respiratory center of the medulla oblongata, airway obstruction, or disorders of the muscles involved in breathing.

•

treatment is to increase the exhalation of CO2 and intravenous administration of HCO3

respiratory alkalosis •

PCO2 falls below 35 mmHg

•

Cause is Hyperventilation due to oxygen deficiency

•

Renal compensation will bring PH to normal range

•

Treatment aimed at increasing the level of CO2 in the body ex inhale and exhale into a paper bag for a short period

metabolic acidosis •

HCO3 (below 22 mEq/liter) and cause blood PH to decrease

•

Causes are Loss of bicarbonate ions due to diarrhea, accumulation of acid (ketosis), renal dysfunction.

•

if the problem is not too severe, hyperventilation can help bring blood pH into the normal range (respiratory compensation).

•

Treatment include intravenous solutions of sodium bicarbonate and correcting the cause of the acidosis.

metabolic alkalosis •

HCO3 above 26 mEq/liter

•

pH (above 7.45)

•

Come causes are Loss of acid due to vomiting, gastric suctioning, or use of certain diuretics; excessive intake of alkaline drugs

•

Respiratory compensation through hypoventilation may bring blood pH into the normal range.

•

Treatment consists of giving fluid solutions to correct Cl−, K+, and other electrolyte deficiencies plus correcting the cause of alkalosis.

•...