Lecture 7

Question 1

What are the Factors which affect the rate of
diffusion through membrane (Fick’s
Law of Diffusion):

Answer 1

*Concentration gradient
* Area of the membrane
* Molecular weight
* Permeability
* The distance through which
diffusion must take place
* Temperature: Kinetic energy
increases with temperature

Question 2

What is Osmosis

Answer 2

diffusion of water
through the semi-permeable
membrane down its own
concentration gradient

Question 3

When Does Osmosis occur?

Answer 3

when the solute is
unable to move down its
concentration gradient

Question 4

When does osmosis stop?

Answer 4

when
equilibrium is reached.

Question 5

What is Osmotic pressure or the pulling pressure

Answer 5

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

Question 6

What is Tonicity (tono = tension)?

Answer 6

the ability of a solution to change the shape ofcells by altering the cells’ internal water volume.

Question 7

What are the 3 states of Tonicity?

Answer 7

Isotonic solution, Hypotonic solutions, Hypertonic solutions

Question 8

What is an isotonic solution

Answer 8

have the same concentrations of solutes in the cells

Example: 0.9% saline or 5% glucose.

Question 9

What is a Hypotonic solution

Answer 9

are more dilute than cells

Cells placed in it, plump up as

example, distilled water

Question 10

What is a hypertonic solution?

Answer 10

have a higher
concentration than the cell

Cells immersed in it → lose water and
crenate.

Example, a strong saline solution.

Question 11

An intravenous hypertonic solution
may help relieve swelling in the brain in
patients with head trauma. How does this work?

Answer 11

Hypertonic solution absorbs water from the
brain swelling by the process of osmosis

Question 12

What is Cell Membrane Potential

Answer 12

Is the presence of different
charges on both sides of the
cell membrane.

Question 13

why is the inside of the cell negative?

Answer 13

due to negative proteins which makes the outside of the cell positive

Question 14

What is polarization?

Answer 14

when inside of the cell is negative and outside of the cell is positive

Question 15

What is the actual amount of restinge potential energy?

Answer 15

–70 mV

Question 16

Where are K+ and Na+ inside or outside?

Answer 16

Na+ → is more outside the cell
(in ECF)
* K+ → is more inside the cell (in
ICF)

Question 17

What are electrolytes

Answer 17

Electrolytes are atoms and
molecules that are able to ionize
and carry an electrical current.

Question 18

What are the electrolytes in plasma

Answer 18

sodium (Na+), chloride
(Cl−), and bicarbonate (HCO3−).

Question 19

What are the electrolytes in intracellular fluid:

Answer 19

potassium
(K+) and phosphate (PO4−3).

Question 20

cations (positively charged)

Answer 20

Na+
and K+.

Question 21

Anions: (negatively charged)

Answer 21

Cl−,
HCO3−, and PO4−3

Question 22

what happens when when electrolytes dissolve

Answer 22

Ions are formed

Question 23

What are the functions of ions

Answer 23

• (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.

Question 24

What is the sodium Potassium Pump

Answer 24

(Na+ /K+ ATPase)
maintains the resting
membrane potential

It ejects 3 Na+ → from
the cell out
And 2 K+ → back into the
cell

Question 25

# T/F Sodium Potassium Pump It is an active transport, that requires ATP energy

Answer 25

True

Question 26

What is the purpose of the What is the sodium Potassium Pump

Answer 26

It constantly “recharges” the cell, keeping its polarity.

Question 27

What % of body does body fluid make up in males and females

Answer 27

55% of total body mass in females 60% of total body mass in males

Question 28

Why do females have less body fluid?

Answer 28

Because they have more fat

Question 29

What are the two compartments of the body that fluid lives?

Answer 29

Intracellular fluid (inside of cells) and extracellular fluid (outside of cells)

Question 30

What is the breakdown of extracellular and intracellular fluid in the body?

Answer 30

Intracellular is 2/3 - 63% Extracellular is 1/3 - 37%

Question 31

What is the breakdown of extracellular fluid

Answer 31

80% is interstitial fluid (inter- = between), between tissue cells – 20% is blood plasma, lymph & others

Question 32

# True or False? water is less present in obese people

Answer 32

true

Question 33

# true or false Water is highest in Infants & reaches 75% of body mass

Answer 33

True

Question 34

What are the ways water enters the body?

Answer 34

in liquids, foods, and as a byproduct of metabolism.

Question 35

What are the ways water exits the body

Answer 35

in urine, sweat, exhaled air, and feces.

Question 36

# True or false we loose exactly the same amount of water we gain

Answer 36

true

Question 37

the reabsorption of salt (NaCl) → automatically leads to the reabsorption of water by

Answer 37

osmosis

Question 38

# True or false? Urine is hypertonic

Answer 38

True | osmolarity is higher than the osmolarity of blood

Question 39

What does Regulation of volume of metabolic water depends on the level of

Answer 39

aerobic respiration, which reflects the demand for ATP | When more ATP is produced → more water is formed.

Question 40

What part of the brain does the thirst center live in

Answer 40

hypothalamus

Question 41

what are four signals that stimulate the thirst center

Answer 41

(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

Question 42

# ``` What happens when water loss is greater than water gain

Answer 42

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

Question 43

What are the four ways water is lost

Answer 43

1. kidneys excrete about 1500 mL in urine 2. skin evaporates about 600 mL (400 mL through insensible perspiration— sweat that evaporates before it is perceived as moisture—and 200 mL as sweat) 3. lungs exhale about 300 mL as water vapor 4. gastrointestinal tract eliminates about 100 mL in feces.

Question 44

How many ml of water are lost per day

Answer 44

2500 mL.

Question 45

# 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.

Answer 45

E. all

Question 46

# * osmolarity is regulated by?

Answer 46

urinary water loss

Question 47

urinary water loss is regulated by?

Answer 47

antidiuretic hormone (ADH = vasopressin).

Question 48

Where is ADH (vasopressin) produced and stored?

Answer 48

produced by the hypothalamus and stored in the posterior pituitary gland

Question 49

What happens when osmolarity increases? osmoreceptors in the hypothalamus stimulate thirst → also increase the synthesis and release of ADH.

Answer 49

osmoreceptors in the hypothalamus stimulate thirst and increase the synthesis and release of ADH.