Foundations of physiology

Question 1

Almost all measurements in medicine are based on the _____ system.

Answer 1

Almost all measurements in medicine are based on the metric system.

Although some commonly used measures are “quirky” – and do not conform to conventional physics (e.g. blood pressure measured in millimeters of mercury: mmHg instead of pascals: Pa), measurements are reported using metric conversion from base units. For example, short durations of time may be reported as “xyz” milliseconds as opposed to “zero point x-y-z” seconds. A list of unit prefixes is provided in Table 1.1.

Question 2

WHAT IS PHYSIOLOGY?

Answer 2

Physiology (Fizz-ee-ol-uh-jee): the branch of biology dealing with the functions and activities of living organisms and their parts.

Therefore, the discipline of physiology has been closely intertwined with medicine. Although physiology is not primarily concerned with structure—as is the case for anatomy, histology, and structural biology—structure and function are inextricably linked because the living structures perform the functions. In addition, physiologic principles are applied to maintain the organism in homeostasis.

Question 3

homeostasis def

Answer 3

the tendency of a system to maintain internal stability, owing to the coordinated response of its parts to any stimulus that disturbs its normal condition or function

Question 4

equilibrium **

Answer 4

a state in which opposing forces or influences are balanced. A system at equilibrium is stable over time, but no energy or work is required to maintain that condition. No free energy will be entering or leaving a system in equilibrium.

Question 5

Steady state: **

Answer 5

a condition where the behavior of the system is unchanging in time. A system that is in a steady state remains constant over time, but requires continual work.

Question 6

negative feedback

Answer 6

where the disturbance to a regulated parameter (response) caused by a certain stimulus is sensed (sensor) and compared to a set point and a signal (feedback) takes action to correct for the initial disturbance (effector). For example, an increase in skin temperature can result in sweating which attempts to reduce body temperature by evaporative cooling.

Question 7

positive feedback occurs. when

Answer 7

the output enhances the original disturbing stimulus.

Question 8

positive feedback examples

Answer 8

Good things don’t usually happen as a result of positive feedback. An example of positive feedback is the progressive increase in atomic breakdown that causes a nuclear explosion. However, there are a few interesting conditions in the body that rely on positive feedback: blood clotting (Figure 1.2), ovulation, urination, and child birth are some examples.

Question 9

The human body is composed of ______ % water (Total Body Water: TBW) of body weight.

Answer 9

The human body is composed of ~50 to 70% water (Total Body Water: TBW) of body weight.

Question 10

Males vs females TBWs.

Answer 10

Males tend to have slightly more TBW than females because males have a lower percentage of adipose tissue than females.

Question 11

Understand homeostasis in terms of negative and positive feedback in physiological
systems **

Answer 11

Homeostasis keeps any given factor within strict operating norms.
One of the most common ways the body accomplishes this is through negative feedback control- where the disturbance to a regulated parameter (response) caused by a certain stimulus is sensed (sensor) and compared to a set point and a signal (feedback) takes action to correct for the initial disturbance (effector).

Question 12

micro

Answer 12

10^-6

Question 13

pico

Answer 13

p

10^-12

Question 14

femto

Answer 14

f

10^-15

Question 15

holding your hand in the air is an example of ?

Answer 15

the steady state

Question 16

homeostasis examples

Answer 16

There are a number of factors that the body strives to maintain within strict margins. Examples include blood pressure, body temperature, blood glucose levels, K+ levels, etc.

Question 17

describe the general steps of negative feedback

Answer 17

Stimulus -> sensor -> control -> effector —->return to impact Stimulus

Question 18

things that go BOOM are an example of ???

Answer 18

IDK ??

Question 19

Describe the importance of water in the body*****

Answer 19

• water acts as a buffer to the body against fluctuations of temperature in the environment.
• water is used to cool the body by evaporation of sweat. this is due to the characteristic high temperature required to vaporize water molecules

Question 20

Describe the importance of water in the body*****

Answer 20

• The human body is composed of ~50 to 70% water. about 2/3 of the water is ICF and 1/3 is ECF. the 1/3 ECF is composed of 3/4 ISF and 1/4 Plasma
• water acts as a buffer to the body against fluctuations of temperature in the environment.
• water is used to cool the body by evaporation of sweat. this is due to the characteristic high temperature required to vaporize water molecules

Question 21

explain why nonpolar molecules like oils and fats do not interact well with water.

Answer 21

nonpolar molecules like oils and fats do not interact well with water.

They separate from water rather than dissolve in it and are called hydrophobic. The hydrophobic effect is particularly important in the formation of cell membranes. The best description is to say that water “squeezes”, or forces, the nonpolar molecules together (Figure 1.6).

Question 22

Mutations of ____ have been shown to result in diabetes insipidus.

Answer 22

Mutations of AQP2 have been shown to result in diabetes insipidus.

Question 23

why is maintaining osmolality across the membrane essential for the cell?

Answer 23

Maintaining osmolality across the membrane is essential for the maintenance of cell volume.

Question 24

1. Understand the general concepts of homeostasis and the principles of positive and negative feedback in physiological systems

Answer 24

1. Understand the general concepts of homeostasis and the principles of positive and negative feedback in physiological systems
   a. Positive feedback (feed forward) - the response to a stimulus triggers further of the same response to the stimulus
   i. ex) tear in blood vessel; contractions during child birth
   b. Negative feedback - response to stimulus to bring back to normal levels
   i. ex) temp control and BP control

Question 25

2. Describe the polar structure of water, and explain how the formation of H-bonds permits the dissociation of salts (such as NaCl) saccharides, and other polar molecules

Answer 25

2. Describe the polar structure of water, and explain how the formation of H-bonds permits the dissociation of salts (such as NaCl) saccharides, and other polar molecules
   a. Water has 2H on one side(ish) of giant electronegative O which pulls electron density toward itself, resulting in d- for O and d+ for Hs.
   b. The formation of H-bonds permits the dissociation of salts and other polar molecules because water can “steal” the H-bonds, forming a shell around it
3. Contrast the definitions of hydrophobic and hydrophilic related to water polarity
   a. Hydrophobic is nonpolar and will not form H-bonds with the polar water molecules, while hydrophilic is polar and will form H-bonds with water

Question 26

3. Contrast the definitions of hydrophobic and hydrophilic related to water polarity

Answer 26

3. Contrast the definitions of hydrophobic and hydrophilic related to water polarity
   a. Hydrophobic is nonpolar and will not form H-bonds with the polar water molecules, while hydrophilic is polar and will form H-bonds with water

Question 27

4. Contrast the following units used to describe concentration: mM, mEq/L, mg/dL, mg%
   * **

Answer 27

4. Contrast the following units used to describe concentration: mM, mEq/L, mg/dL, mg%
   a. mM - 1 mole of substance in 1 L of solution (divided by 1000)
   b. mEq/L - amount of charged solute in solution (Equivalency)
   i. 1 mol KCl → 1 Eq K and 1 Cl
   ii. 1 mol CaCl2 → 1 Eq Ca2+ and 2 Eq Cl-
   c. mg/dl or mg% (same) - concentration used in medicine

Question 28

5. List the typical relative values for plasma, interstitial, and intracellular concentrations of Na, K, H+, HCO3, Cl, Ca, and Glc

Answer 28

5. List the typical relative values for plasma, interstitial, and intracellular concentrations of Na, K, H+, HCO3, Cl, Ca, and Glc
   a. Na - high outside, low inside
   b. K - low outside, high inside
   c. H+ - pH is 7.4
   d. HCO3 - low outside, even lower inside
   e. Cl - high outside, low inside
   f. Ca - low outside, veryyyy low inside
   g. Glc - low outside, lower inside

Remarkably, given all the concentration differences for individual solutes, the total solute concentration (osmolality) is the same in ICF and ECF.

Question 29

6. Differentiate between the terms osmole, osmolarity, osmolality, and tonicity; list the typical values for plasma osmolality

Answer 29

6. Differentiate between the terms osmole, osmolarity, osmolality, and tonicity; list the typical values for plasma osmolality
   a. Osmole - number of particles when measuring osmolarity or osmolality
   b. Osmolarity - number of particles into which a solute dissociates into
   i. Number of osmoles in 1 L of solvent
   c. Osmolality - number of osmoles in 1 kg of solvent
   d. Tonicity - relative difference in osmolality across membrane
   i. Hypertonic, isotonic, hypotonic
   e. Plasma osmolality usually 290 across the board

Question 30

7. Compute the anion gap

Answer 30

7. Compute the anion gap
   a. Difference between concentration of major cations and major anions and represents concentration of unmeasured anions and plasma proteins
   i. ([Na] + [K]) - ([HCO3] + [Cl])
   ii. [Na] - ([HCO3] + [Cl])

Question 31

8. Contrast the osmotic pressure generated across a cell membrane by a solution of particles that freely cross the membrane with that of a solution with the same osmolality, but cannot cross the cell membrane

Answer 31

8. Contrast the osmotic pressure generated across a cell membrane by a solution of particles that freely cross the membrane with that of a solution with the same osmolality, but cannot cross the cell membrane
   a. Osmotic pressure would be greater with the semipermeable membrane because in the former, the solute would be more evenly distributed and the water would have less “incentive” to cross.

Question 32

9. Define water movement across the cell membrane through aquaporins

Answer 32

9. Define water movement across the cell membrane through aquaporins
   a. Water is small, but not permeable because it is polar. So aquaporins are polar protein channels that are open channels and allow water to pass through membrane