Osmosis and Membrane Process

Question 1

Osmolality

Answer 1

measurement of solute concentration in fluid
High osmolality = high solute concentration
Range of serum osmolality varies in species

Question 2

Increased osmolality of blood triggers

Answer 2

Desire to drink
Release of antidiuretic hormone

Question 3

Decreased osmolality of blood

Answer 3

Inhibits desire to drink
Inhibits release of antidiuretic hormone

Question 4

Serum osmolality tests may be ordered to asses

Answer 4

Hydration status
High osmolality if dehydrated
Hyperglycaemia
Functioning of hypothalamus
Poisoning by ethylene glycol

Question 5

Antifreeze poisoning

Answer 5

Series of oxidation reactions in liver and kidneys metabolize ethylene glycol
Toxic metabolites cause metabolic acidocis and nephrotoxosis
Oxalate is cytotoxic

Question 6

Isotonic fluid therapy

Answer 6

Osmolality comparable to that of normal blood
extracellular fluid has same concentration of dissolved substances as intracellular fluid
Example : 0.9% NaCl (normal saline)

Question 7

Hypertonic fluids

Answer 7

Osmolality is greater than that of blood
Extracellular fluid has higher concentration of solutes than the cytoplasm
Water leaves the cell, causing the cell to shrink and become shrivelled

Question 8

Hypotonic fluids

Answer 8

Osmolality is less than that of blood
Higher concentration of solutes in the cytoplasm than in the extracellular fluid
Water flows into the cell and causes it to swell and possibly to break

Question 9

Electrolytes are

Answer 9

Small and most abundant solute in body
Greatest ability to cause fluid shifts between compartments
Concentration in body fluids is expressed as milliequivalents per litre

Question 10

Osmolality and water

Answer 10

Any change in the concentration of any solute incurs movement of water from one compartment to another
Water crosses cell membrane
or
Water crosses capillary walls

Question 11

Edema is a

Answer 11

Abnormal, excess accumulation of fluid in tissue
Common sign of abnormal movement of fluid from vascular space into interstitial space
Pulmonary edema
Fluid leaking into lungs
Cutaneous edema
Leaking into skin

Question 12

Crystalloid fluid

Answer 12

Composed of water rich with electrolytes
hypotonic or isotonic
Solutes are small
Able to cross the vascular wall
Good for rehydrating extravascular spaces and correcting acid/base imbalances

Question 13

Colloid fluid

Answer 13

Heavy molecules suspended in isotonic crystalloid
Solutes too large to cross vascular wall
“hold” fluid in intravascular space

Question 14

Passive process

Answer 14

Requires no energy

Question 15

Active process

Answer 15

Require energy to be used

Question 16

Three types of membrane permeability

Answer 16

Freely permeable
Impermeable
Selectively permeable

Question 17

Diffusion

Answer 17

Kinetic movement of molecules from higher to lower concentration
Concentration gradient
Factors determining whether molecule may pass through cell membrane:
Molecular size
Lipid solubility
Molecular charge
Channels allow certain ions to pass through

Question 18

Facilitated diffusion

Answer 18

Selective carrier proteins assist in movement of molecules from higher to lower concentration
Process limited by the number of carrier proteins available
Passive processes
Requires no energy from cell
Example
Glucose moves into muscle and fat cells

Question 19

Osmosis

Answer 19

Passive movement of water through a semipermeable membrane from area of low solute concentration to higher solute concentration
Example
water moves from stomach into bloodstream
Concentration balance = equilibrium
Osmotic pressure – force of water moving from one side of membrane to the other because of differences in solute concentration
Normally extracellular fluid has the same concentration of dissolved solutes as intracellular fluid

Question 20

Oncotic pressure

Answer 20

Difference between:
osmotic pressure of blood
osmotic pressure of interstitial fluid or lymph
Important force in maintaining fluid balance

Question 21

Filtration

Answer 21

Based on a pressure gradient
Liquids may be pushed through membrane if pressure on one side is greater than that on the other side
Hydrostatic pressure – caused by beating heart
Example: filtration of blood in kidneys

Question 22

Dialysis

Answer 22

Example of use of basic scientific principles to help resolve a clinical problem
Dialysis is a type of diffusion used most commonly in animals with acute kidney failure
To remove toxins the animal’s blood is circulated through an artificial kidney with semipermeable filaments
An electrolyte solution called dialysate is driven through the artificial kidney in the opposite direction of the blood
Small solutes move out of the blood into the dialysate
Move from higher solute concentration to a lower one

Question 23

Reasons why molecules can’t enter cells by passive root

Answer 23

Not lipid soluble
Too large to pass through a membrane pore
Going against the concentration gradient

Question 24

Active transport 2 types

Answer 24

Synport system
Antiport system

Question 25

Cytosis two types

Answer 25

Endocytosis Exocytosis

Question 26

All cells actively carry these electrolytes

Answer 26

Na+ K+ Ca2+ Mg2+

Question 27

Symport system

Answer 27

All substances are moved in the same direction

Question 28

Antiport system

Answer 28

some substances moved in one direction others moved in the opposite direction

Question 29

Cytosis

Answer 29

Mechanism for bringing nutrients into the cell and ejecting waste

Question 30

Endocytosis

Answer 30

Transports large particles or liquids into the cell by engulfing them Phagocytosis Pinocytosis Receptor-mediated endocytosis

Question 31

Phagocytosis

Answer 31

Cells engulf solid material Vesicle formed called a phagosome Macrophage – debris, dead cells, invaders Phagosome fuses with lysosomes for digestion White blood cell – bacteria, viruses Macrophages and WBC can move by ameboid motion Pseudopodia

Question 32

Pinocytosis

Answer 32

Cells engulf liquid material Involves only minute infolding of plasma membrane Important in cells lining small intestine and renal tubules

Question 33

Receptor mediated endocytosis

Answer 33

Very specific process Occurs in cells with specific proteins in their plasma membranes Ligands bind to specific receptors Vesicle is formed = coated pit Insulin binding to insulin receptors

Question 34

Exocytosis

Answer 34

Cells export intracellular substances into the _extracellular_ space Substances packaged in vesicles by ER and Golgi body Vesicles move through cytoplasm to cell surface, fuse with plasma membrane, and release contents into extracellular fluid Excretion – waste products Secretion – manufactured molecules Neurons release packages of acetylcholine Endothelial cells lining trachea secrete mucus Mass cells release thousands of granules of histamine during allergic reactions

Question 35

Principle ions of membrane potential

Answer 35

K+ and Na+

Question 36

Normally more what inside cell

Answer 36

K+

Question 37

What is more concentrated outside of the cell

Answer 37

Na+

Question 38

Every cycle of active trasnport

Answer 38

3 Na+ exit for every 2 K+ entering

Question 39

changes that can alter resting membrane potential

Answer 39

Environmental tonicity Osmotic pressure Temperature Contact with neighboring cells

Question 40

Changes that alter resting membrane potential can alter the flow of

Answer 40

metabolites Alters behavior of some structural and enzymatic proteins Example = muscle cells – contract due to changes in membrane potential

Question 41

Treatment for anti freeze poisoning

Answer 41

IV fluid therapy to restore hydration, correct electroyte imbalances, promote kidney function and excretion of ethylene glycol Sodium bicarbonate often included to counteract excessive acid levels Solution of diluted ethanol often given as treatment Works by competing with ethylene glycol for binding site on the enzyme that converts ethylene glycol into toxic metabolites Ethylene glycol can be eliminated from the body unchanged

Question 42

Elements in electrolytes

Answer 42

Calcium Chloride Magnesium Phosphorus Potassium Sodium

Question 43

What happens if oncotic pressure is disturbed

Answer 43

If levels of protein in plasma decrease, balance is disrupted Subcutaneous edema Fluid leaks into skin Ascites Fluid leaks into abdomen

Question 44

Factors determining whether molecules may pass through the cell membrane

Answer 44

Molecular size Lipid solubility Molecular charge Channels allow certain ions to pass through