Osmoregulation and Acid-Base Balance

Flashcards covering Osmolarity, body fluids, osmoregulation, and physiological buffers.

Intracellular Fluid (ICF)

Fluid inside the cells, making up approximately 55% of total body water.

Extracellular Fluid (ECF)

Fluid outside the cells, making up approximately 45% of total body water.

Plasma Membrane

Separates ICF from surrounding interstitial fluid.

Blood Vessel Wall

Separates interstitial fluid from plasma.

Organic Substances in Body Fluids

Include glucose, amino acids, fatty acids, hormones, and enzymes.

Inorganic Substances in Body Fluids

Include sodium, potassium, calcium, magnesium, chloride, phosphate, and sulphate.

Sodium (Na+)

Most abundant cation in ECF, important for transports and osmolarity pressure.

Potassium (K+)

Most abundant cation in ICF, important for osmolarity pressure and resting membrane potential.

Calcium (Ca2+)

Low ICF concentration, involved in regulation processes of cells such as exocytosis and muscle contraction.

Magnesium (Mg2+)

Found in ICF and ECF, cofactor of enzymes and involved in synaptic transmission.

Chloride (Cl-)

Most abundant anion in ECF, moves easily between ECF and ICF due to leakage channels.

Electrolytes

ions in body fluid

ECF Cation Abundance

Na+ is most abundant.

ECF Anion Abundance

Cl- is most abundant.

ICF Cation Abundance

K+ is most abundant.

ICF Anions

Proteins and phosphates (HPO4 2-).

Na+/K+ Pumps

Play a major role in keeping K+ high inside cells and Na+ high outside cells.

Interstitial Fluid

Approximately 80% of ECF, present between the cells.

Plasma

Approximately 20% of ECF, present in blood.

Transcellular Fluid

Special extracellular fluid including saliva, chyme, cerebrospinal fluid, synovial fluid, etc.

Cerebrospinal Fluid (CSF)

Clear, colorless liquid formed within the cavities of the brain and around the spinal cord.

Synovial Fluid

Produced by synovial membranes in joints.

Lymph

Clear and colorless fluid, returns protein from tissue spaces into blood.

Milk

Secreted by mammary glands, a complete natural food.

Amniotic Fluid

Liquid produced by membranes and fetus, provides physical protection to the fetus.

Aqueous Humor

Fluid that fills the interior chamber of the eye, secreted by the ciliary body.

Sweat

Secretion of sweat gland, regulates body temperature by cooling and evaporation.

Tears

Produced by lachrymal glands, lubricate the surface of the cornea.

Osmoregulation

Regulates solute concentrations and balances the gain and loss of water.

Excretion

Gets rid of nitrogenous metabolites and other waste products.

Osmolarity

The solute concentration of a solution, determines the movement of water across a selectively permeable membrane.

Isoosmotic

When two solutions have equal water movement in both directions.

Water Movement

Water moves from hypoosmotic (low solute) to hyperosmotic (high solute) solutions.

Osmoconformers

Marine animals that are isoosmotic with their surroundings and do not regulate their osmolarity.

Osmoregulators

Expend energy to control water uptake and loss in a hyperosmotic or hypoosmotic environment.

Stenohaline

Animals that cannot tolerate substantial changes in external osmolarity.

Euryhaline

Animals that can survive large fluctuations in external osmolarity.

Marine Bony Fishes

Hypoosmotic to sea water, lose water by osmosis and gain salt.

Marine Invertebrates

Extracellular ionic & osmotic concentrations close to sea water with conserved intracellular ionic concentration.

Elasmobranchs

Cartilaginous fishes with low extracellular ionic concentration; solute gap filled by urea.

Trimethylamine N-oxide (TMAO)

Stabilizes the destabilizing effect of urea on proteins.

Freshwater Animals

Constantly take in water by osmosis from their hypoosmotic environment and lose salts by diffusion.

Anadromous Fishes

Migrate from sea to freshwater to spawn (e.g., salmon).

Catadromous Fishes

Migrate from freshwater to sea to spawn (e.g., eel).

Diadromous Fishes

Fishes that migrate between fresh and salt water

Anhydrobiosis

Adaptation where aquatic invertebrates in temporary ponds lose almost all body water and survive in a dormant state.

Land Animals

Manage water budgets by drinking and eating moist foods and using metabolic water.

Transport Epithelia

Specialized epithelial cells that regulate solute movement.

Salt Glands

Remove excess sodium chloride from the blood in marine birds.

Osmolytes

Small solutes used by cells to maintain cell volume.

Compatible Solutes

Osmolytes that do not perturb macromolecules in the cell and are interchangeable.

Trehalose

Carbohydrate osmolytes.

Glycerol

Polyhydric alcohol act as osmolytes.

Alanine

Amino acid derivatives use as osmolytes.

Urea

Methyl amines act as osmolytes.

Metabolic Rate and Osmoregulation

Energetic cost of osmoregulation is 3-7% of resting metabolic rate in fresh water species.

Animal Cells and Osmotic Equilibrium

Must be in osmotic equilibrium with their surrounding environments to prevent rupture

Osmoregulation

balances the uptake and loss of water and solutes.

Bicarbonate buffer system

Important ECF physiological buffer systems

Phosphate buffer

Important ICF physiological buffer systems

Haemoglobin

Important RBC physiological buffer systems

Plasma protein

Important Plasma physiological buffer systems

Carbonic acid formula

H2CO3

Bicarbonate formula

HCO3-

buffer

Response to fluctuations in pH

hydrogen phosphate ions

HPO42-

dihydrogen phosphate

H2PO4-

OH added

H2PO4- is produced

H+ added

HPO4 2- is produced

free and terminal amino acids

proteins in protein buffer systems

pH rises

carboxyl group of amino acid dissociates

amino acid buffer

act as base absorbing H+

hemoglobin buffer system

helps prevent changes in pH when Plasma PCO2 is rising or falling

buffer systems

temporary solution to acid-base imbalance

Acid–Base Disorders

imbalance between CO2 generation in peripheral tissues and CO2 excretion at lungs

Metabolic Acid–Base Disorders

generation of organic or fixed acids or conditions affecting HCO3 concentration

hypoventilation

Primary sign respiratory acidosis, low plasma pH due to hypercapnia

cardiac arrest

causes respiratory acidosis

respiratory rate increases

compensation for Respiratory Acidosis

hyperventilation

Primary sign respiratory alkalosis, high plasma pH due to hypocapnia

stress/panic

causes respiratory alkalosis

Respiratory compensation

decreased respiratory rate in the case of Respiratory Alkalosis

Lactic acidosis

anaerobic cellular respiration, cause metabolic acidosis

ketoacidosis

excess ketone bodies, cause metabolic acidosis

kidney damage

Cause metabolic acidosis

Respiratory compensation metabolic acidosis

increased RR, Renal: secrete H+, reabsorb and generate HCO3

Elevated HCO3 concentrations

Metabolic Alkalosis; Bicarbonate ions interact with H in solution forming H2CO3

Gastric HCL generation

Metabolic Alkalosis; Alkaline tide

Loss of HCL

Metabolic Alkalosis; vomiting

Reduced RR

increased HCO3 loss at kidney, Retention of HCl; Respiratory compensation: metabolic alkalosis causes

Kidney response to alkalosis

H+ secretion, HCO3 reabsorption

Acidosis and Alkalosis Detection

:blood tests for pH, PCO2 and HCO3

Acidosis normal Pco2

Metabolic Acidosis; Not increased

Acidosis Increased Pco2 (>50)

respiratory ACIDOSIS; Primary cause is hypoventilation

Alkalosis increased Pco2 (>45)

Metabolic Alkalosis; HCO3 will be elevated

Alkalosis decreased Pco2

respiratory alkalosis; Primary cause is hyperventilation