Basic Principles of Physiology I

Question 1

Body composition of water for men, women, and neonates

Answer 1

Men: 60%
Women: 50% (reflects increased body fat)
Neonates: 70%

Question 2

Body fluids can be divided into two categories based on their location relative to the cell membrane

Answer 2

Intracellular (40% of body weight) and extracellular fluid (20% of body weight)

Question 3

Extracellular fluid is composed of what?

Answer 3

Interstitial fluid (15%): present in the spaces between cells
Blood plasma (5%)

Question 4

Normal daily intake of water

Answer 4

2. 5L

1. 5L is excreted as urine, 100mL is lost in sweat, and 100mL is present in feces

Question 5

Average blood volume

Answer 5

5L (3L of plasma and 2L of erythrocytes)

Question 6

Normal hematocrit (HCT) for men/women

Answer 6

45% for men and postmenopausal women

38% for menstruating women +/-5%

Question 7

An unequal distribution of ions results in the establishment of ____ differences across cell membranes

Answer 7

voltage

Question 8

Trauma is associated with progressive loss of…?

Answer 8

Potassium through the kidneys d/t increased secretion of vasopressin, and in part (depending on surgery) due to NGT suctioning and direct K+ loss

Question 9

Movement of water (solvent molecules) across a semipermeable membrane from a compartment of lower solute concentration to an area of higher solute concentration

Answer 9

osmosis

Question 10

D5W

Answer 10

Initially isotonic when infused, but glucose is metabolized so the net effect is that of infusing a HYPOtonic solution

Question 11

LR in 5% dextrose

Answer 11

Initially HYPERtonic but as glucose is metabolized, the solution becomes less hypertonic

Question 12

The role of crystalloids in restoring perfusion in microcirculation

Answer 12

After 20-30m, an estimated 75-80% of isotonic NS or LR solution will have distributed outside the confines of the circulation, thus limiting the efficacy of these solutions in treating HYPOvolemia

Question 13

Ratio of extracellular to intracellular fluid

Answer 13

In infants, this is greater than adults (dehydration develops more rapidly and is often more severe in the young)

Question 14

Cell membrane and solubility

Answer 14

Each cell is surrounded by a lipid bilayer that acts as a permeable barrier, allowing the cell to maintain a cytoplasmic composition different from the extracellular fluid. Lipid bilayers are nearly impermeable to water-soluble substances (ions, glucose, etc.). Conversely, fat-soluble substances (steroids) and gases readily cross cell membranes.

Question 15

Simple diffusion

Answer 15

O2, CO2, and nitrogen move through cell membranes by simple diffusion

Question 16

Exocytosis

Answer 16

Neurotransmitters are ejected from cells via exocytosis, a process that requires Ca++ and resembles endocytosis in reverse.

Question 17

Na/K ATPase

Answer 17

ATP-dependent sodium and potassium transporter on the cell membrane that ejects three sodium ions from the cell in exchange for the import of two potassium ions

Question 18

Ion channels

Answer 18

Transmembrane proteins that generate electrical signals in the brain, nerve, heart, and skeletal muscles

Question 19

Phagocytosis and pinocytosis

Answer 19

Phagocytosis: Ingestion of solid particles
Pinocytosis: Ingestion of dissolved particles

Question 20

Genes encoding the protein ion channels may be defecting leading to…

Answer 20

Diseases such as cystic fibrosis (chloride channel defect) and long QT syndrome (mutant K channels or less commonly Na channels)

Question 21

Nucleus

Answer 21

Made up of 46 chromosomes except for the nucleus of an egg cell, which contains 23

Question 22

Cytoplasm

Answer 22

Consists of water, electrolytes, and proteins (including enzymes, lipids, carbs) and also contains numerous organelles

Question 23

Mitochondria

Answer 23

Power-generating unit of cells containing both enzymes and substrates of the tricarboxylic acid cycle (Krebs cycle) and the electron transport chain

Question 24

Endoplasmic Reticulum (ER)

Answer 24

A complex lipid bilayer that folds and creates vesicles in the cytoplasm. The portion of the membrane containing ribosomes is the RER, and the part that lacks is the SER. The smooth portion of the ER functions in the synthesis of lipids, metabolism of carbs, and other enzymatic processes. The sarcoplasmic reticulum is found in muscle cells, where it serves as a reservoir for Ca++

Question 25

5 major types of protein ion channels

Answer 25

Ca++, Na+, Nonselective, Cl-, and K+

*Flow of ions through these channels (Ca++ and Na+ IN, K+ OUT) determines the transmembrane potential