Lecture 7 Flashcards
Learn Lecture 7
What are the Factors which affect the rate of
diffusion through membrane (Fick’s
Law of Diffusion):
*Concentration gradient
* Area of the membrane
* Molecular weight
* Permeability
* The distance through which
diffusion must take place
* Temperature: Kinetic energy
increases with temperature
What is Osmosis
diffusion of water
through the semi-permeable
membrane down its own
concentration gradient
When Does Osmosis occur?
when the solute is
unable to move down its
concentration gradient
When does osmosis stop?
when
equilibrium is reached.
What is Osmotic pressure or the pulling pressure
the measure of tendency of a
solution to pull water into it by
osmosis because of the relative
concentration of non-penetrating
solute and water
What is Tonicity (tono = tension)?
the ability of a solution to change the shape ofcells by altering the cells’ internal water volume.
What are the 3 states of Tonicity?
Isotonic solution, Hypotonic solutions, Hypertonic solutions
What is an isotonic solution
have the same concentrations of solutes in the cells
Example: 0.9% saline or 5% glucose.
What is a Hypotonic solution
are more dilute than cells
Cells placed in it, plump up as
example, distilled water
What is a hypertonic solution?
have a higher
concentration than the cell
Cells immersed in it → lose water and
crenate.
Example, a strong saline solution.
An intravenous hypertonic solution
may help relieve swelling in the brain in
patients with head trauma. How does this work?
Hypertonic solution absorbs water from the
brain swelling by the process of osmosis
What is Cell Membrane Potential
Is the presence of different
charges on both sides of the
cell membrane.
why is the inside of the cell negative?
due to negative proteins which makes the outside of the cell positive
What is polarization?
when inside of the cell is negative and outside of the cell is positive
What is the actual amount of restinge potential energy?
–70 mV
Where are K+ and Na+ inside or outside?
Na+ → is more outside the cell
(in ECF)
* K+ → is more inside the cell (in
ICF)
What are electrolytes
Electrolytes are atoms and
molecules that are able to ionize
and carry an electrical current.
What are the electrolytes in plasma
sodium (Na+), chloride
(Cl−), and bicarbonate (HCO3−).
What are the electrolytes in intracellular fluid:
potassium
(K+) and phosphate (PO4−3).
cations (positively charged)
Na+
and K+.
Anions: (negatively charged)
Cl−,
HCO3−, and PO4−3
what happens when when electrolytes dissolve
Ions are formed
What are the functions of ions
- (1) certain ions control the
osmosis of water between fluid
compartments. - (2) help maintain the acid–base
balance. - (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.
What is the sodium Potassium Pump
(Na+ /K+ ATPase)
maintains the resting
membrane potential
It ejects 3 Na+ → from
the cell out
And 2 K+ → back into the
cell
T/F
Sodium Potassium Pump It is an active transport,
that requires ATP energy
True
What is the purpose of the What is the sodium Potassium Pump
It constantly “recharges”
the cell, keeping its
polarity.
What % of body does body fluid make up in males and females
55% of total body mass in
females
60% of total body mass in males
Why do females have less body fluid?
Because they have more fat
What are the two compartments of the body that fluid lives?
Intracellular fluid (inside of cells) and extracellular fluid (outside of cells)
What is the breakdown of extracellular and intracellular fluid in the body?
Intracellular is 2/3 - 63%
Extracellular is 1/3 - 37%
What is the breakdown of extracellular fluid
80% is interstitial fluid (inter- =
between), between tissue cells
– 20% is blood plasma, lymph &
others
True or False?
water is less present in obese people
true
true or false
Water is highest in Infants & reaches 75% of body mass
True
What are the ways water enters the body?
in liquids, foods, and as a byproduct of metabolism.
What are the ways water exits the body
in urine,
sweat, exhaled air, and feces.
True or false
we loose exactly the same
amount of water we gain
true
the reabsorption of salt (NaCl)
→ automatically leads to the
reabsorption of water by
osmosis
True or false?
Urine is hypertonic
True
osmolarity is higher than the
osmolarity of blood
What does Regulation of volume of metabolic
water depends on the level of
aerobic respiration, which reflects
the demand for ATP
When more ATP is produced →
more water is formed.
What part of the brain does the thirst center live in
hypothalamus
what are four signals that stimulate the thirst center
(1) volume receptors in the atria →
detect the decrease in blood volume
* (2) baroreceptors in blood vessels →
detect the decrease in blood
pressure
* (3) angiotensin II → that is formed
due to activation of the reninangiotensin- aldosterone pathway by
the decrease in blood pressure
* (4) neurons in the mouth that detect
dryness due to a decreased flow of
saliva
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What happens when water loss is greater than water gain
dehydration → a decrease in blood volume and an increase in osmolarity of body fluids → blood pressure fall → increased blood osmolarity →stimulates thirst center (osmoreceptors) in the hypothalamus
What are the four ways water is lost
- kidneys excrete about 1500 mL
in urine - skin evaporates about 600 mL
(400 mL through insensible
perspiration— sweat that
evaporates before it is
perceived as moisture—and 200
mL as sweat) - lungs exhale about 300 mL as
water vapor - gastrointestinal tract eliminates
about 100 mL in feces.
How many ml of water are lost per day
2500 mL.
Which of the following
statements about body
water is correct?
a. Males have a higher
percentage of body water
by weight than females.
– b. Most of the body’s
water is found inside cells.
– c. Water can be lost from
the body in exhaled air.
– d. A portion of daily water
intake comes from water
produced during
metabolism.
– e. All of these statements
are correct.
E. all
*
osmolarity is regulated by?
urinary
water loss
urinary water loss is regulated by?
antidiuretic hormone (ADH =
vasopressin).
Where is ADH (vasopressin) produced and stored?
produced by the hypothalamus and stored in the posterior pituitary gland
What happens when osmolarity increases?
osmoreceptors in the
hypothalamus stimulate thirst →
also increase the synthesis and
release of ADH.
osmoreceptors in the hypothalamus stimulate thirst and increase the synthesis and
release of ADH.
