Unit 4 - Osmosis and Membrane Processes Flashcards
What is osmolality?
Measurement of solute concentration in a fluid
What does high osmolality equal?
High solute concentration
What does increased osmolality in blood tirgger? 2
Desire to drink
Release of antidiuretic hormone
What does decreased osmolality in blood trigger? 2
inhibits desire to drink
Inhibits release of antidiuretic hormone
What does serum osmolality tests assess? 4
Hydration status
hyperglycemia
functioning of hypothalamus
posioning by ethylene glycol
Describe antifreeze poisoning. What happens and how do you treat it?
Oxidation reactions in liver + kidneys metabolize ethylene glycol
Toxic metabolites causes metabolic acidosis and nephrotoxosis. Oxalate is cytotoxic
IV fluid therapy to restore hydration,
correct electrolyte imbalances, promote
kidney function and excretion of ethylene
glycol
Sodium bicarbonate often included to
counteract excessive acid levels 6
How do you treat antifree poisoning
Solution of diluted ethanol often given as
treatment
Works by competing with ethylene
glycol for binding site on enzyme that
converts ethylene glycol into toxic
metabolites
Ethylene glycol can be eliminated from
the body unchanged
Describe Isotonic fluid therapy
- Osmolality comparable to that of normal blood
Extracellular fluid has same conc. of dissolved substances as intracellular fluid
What is an ex of isotonic fluid therapy
0.9 % NaCl (saline)
Describe Hypotonic fluids
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
Describe hypertonic fluids
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 shriveled
Describe Electrolytes
Small and most abundant solute in body
Greatest ability to cause fluid shifts
between compartments
Concentration in body fluids is
expressed as milliequivalents per liter
Describe organic molecules in body fluids. List some examples. 4
Large and not as numerous
Unevenly distributed among fluid
compartments
Examples: soluble proteins,
phospholipids, cholesterol,
triglycerides
What is the relationship between osmolality and water?
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
13
Describe what an edema is. What are common signs?
Abnormal, excess accumulation of
fluid in tissue
Common sign of abnormal movement
of fluid from vascular space into
interstitial space
Pulmonary edema
Cutaneous edema
Describe the type of fluid: Crystalloid
Compo of water rich with electrolytes. Either hypotonic or isotonic
- Solutes are small, can cross vascular wall
- Good for rehydration of extravascular spaces and correcting acid/base imbalances
Describe the type of fluid: Colloid
Heavy molecules suspended in
isotonic crystalloid
Solutes too large to cross vascular
wall
“hold” fluid in intravascular space
Give two specific examples of solutes in the body
Electrolytes, organic molecules
What type of fluid is used for fluid therapy contains large solutes
Hypertonic?
What is membrane processes used for?
Absorption of nutrients or excretion
of waste through plasma membrane
may occur with or without
expenditure of energy (ATP)
What two membrane processes are there?
Passive processses
Active processes
What three ways can a membrane be permeable
freely permeable
impermeable
selectively impermeable
What is diffusion?
Kinetic movement of molecules from higher to lower conc.
= Concentration gradient
What factors determin whether a cell may pass through the cell membrane?
molecular size
lipid solubility
molecular charge
channels allow certain ions to
pass through
What is facilitated diffusion? Give an example
Selective carrier proteins assist in
movement of molecules from higher
to lower concentration
Process limited by number of carrier
proteins available
Requires no energy from cell
EX. glucose moves into muscle
and fat cells
What is osmosis? Give an example
Passive movement of water through a
semipermeable membrane from area
of low solute concentration to higher
solute concentration
EX. water moves from
stomach into bloodstream
What is osmotic pressure?
force of water moving from one
side of membrane to the other because of
differences in solute concentration
The difference between oncotic pressure and osmotic pressure? (not good)
Osmotic pressure is the force that drives the movement of water molecules from a region of low solute concentration to a high solute concentration, while oncotic pressure is the force exerted by proteins in the blood that draws water into the blood vessels.
Oncotic = Pull
What happens when the LVLS of protein in plasma decreased and the balance is disrupted?
SQ edema
ascites
Describe filtration. Give an example
It is based on a pressure gradient
Liquids may be pushed thru membrane if pressure on one side is greater than that of the other side
EX: filtration of blood in kidneys
What is hydrostatic pressure caused by?
beating heart
What is dialysis? What is it used for?
A type of diffusion used for animals with acute kidney failure
to remove toxins the animal’s blood
is circulated through an artificial
kidney with semipermeable
filaments
How does dialysis work?
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
Is diffusion an active or passive membrance process?
Passive. It moves from a high conc. To a low conc. So it has a uniform space
What is another name for hydrostatic pressure in the body?
Capillary blood pressure?
The pushing force of water
What is active membrane processes?
Movement of molecules and substances
across the cell membrane in which the
cell is required to use energy
Why can’t some molecules enter the cell by passive routes? 3
not lipid soluble
too LG to pass membrane pore
Going against conc. gradient
What two things make up active transport? What two things make up Cytosis?
- Symport system
- Antiport system
- Endocytosis
- Exocytosis
Describe active transport and how it works?
Some amino acids and ions must rely
on a carrier protein and energy (ATP)
to move them through the plasma
membrane
What four electrolytes can all cells active transport?
Na+, K+, Ca2+, Mg2+
What is the differences between the symport system and antiport system?
Symport : all substances move in the same direction
Antiport : Some substances move in one directions, other move in opposite direction
What are the differences in ionic concentrations?
Critical in maintaining proper fluid
balances in all cells and tissue types
Important in normal functioning of
irritable cells
Energy from cellular respiration
fuels active transport
Examples: myofibrils and neurons
What is cytosis? How many types and what are they?
Mechanism for bringing nutrients into
the cell and ejecting waste
requires ATP
Two types:
endocytosis
exocytosis
What is endocytosis?
Transports large particles or liquids into
the cell by engulfing them
phagocytosis
pinocytosis
receptor-mediated endocytosis
What is phagocytosis?
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
How do macrophages and WBC move?
Amoeboid motion called pseudopodia
What is pinocytosis?
Cells engulf liquid material
Involves only minute infolding of
plasma membrane
Important in cells lining small
intestine and renal tubules
Describe receptor-mediated endocytosis
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
What is exocytosis?
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
Neurons release packages of
acetylcholine
Endothelial cells lining trachea
secrete mucus
Mast cells release thousands of
granules of histamine during allergic
reactions
What is exocytosis simplified into two parts?
Excretion – waste products
Secretion – manufactured
molecules
Describe what membrane potential = voltage?
Potential electrical energy created by
the separation of opposite charges
Refers to changes in distribution of
charged particles on either side of the
cell membrane
Plasma membrane more permeable
to some molecules than others
What is the normal range of membrane potential?
-20 to -22 millivolts (mV)
What are the principal ions involved in membrane potential? What do they do?
K+ and Na+
Normally more K+ inside cell
K+ moves out of cell by diffusion
Na+ more concentrated outside the cell
Cannot easily enter the cell
Every cycle of active transport:
3 Na+ exit for every 2K+ entering
What changes are included with resting membrane potential? 4
environmental tonicity
osmotic pressure
temperature
contact with neighboring cells
How can a change of membrane potential affect a cell? list an example of it
Alters behaviour of some structural and enzymatic proteins
ex. muscle cells - contract due to changes in membrane potential
Which type of exocytosis involves waste products being released?
excretions
