Concepts in Human Physiology - Unit 01 Review

Flashcard study set covering introductory human physiology, homeostasis concepts, basic inorganic/organic cell chemistry, organelle functions, plasma membrane transport mechanisms, and electrical potentials.

According to Isaac Asimov, what is the most exciting phrase to hear in science that heralds new discoveries?

"that's funny…"

What contribution did Claude Bernard (1813-1878) make to the concept of homeostasis?

He proposed that the internal environment (blood) is separated from the external environment by the skin/integument and maintained at a relatively constant composition to provide stable conditions for cell function.

Who coined the term "homeostasis" to describe the relative stability of the internal environment?

Walter Cannon (1871-1945).

How is homeostasis defined in physiology?

The maintenance of a stable internal environment, operating as a dynamic state of equilibrium necessary for normal body functioning and sustaining life.

In the homeostatic control system mechanism shown in the diagram, what pathway carries information from the receptor to the control center, and what pathway carries information from the control center to the effector?

The afferent pathway carries input from the receptor to the control center, while the efferent pathway carries output from the control center to the effector.

How do negative feedback mechanisms operate in homeostatic control?

They shut off the original stimulus or reduce its intensity to bring the variable back to its homeostatic set point (e.g., household thermostat or insulin regulation of blood glucose).

In what three specific biological processes does positive feedback occur in the human body?

Blood clotting, before ovulation, and during the birth of a baby.

What is the distinction between anatomy and physiology?

Anatomy is the study of the structure and shape of the body and its parts, whereas physiology is the study of how the body and its parts work or function.

Which four elements account for $96\text{\%}$ of human body mass?

Carbon (C), Oxygen (O), Hydrogen (H), and Nitrogen (N).

What are the four vital physiological properties of water?

High heat capacity, polarity/solvent properties, chemical reactivity (such as hydrolysis), and cushioning.

How are acids and bases chemically defined in terms of hydrogen ions?

Acids release hydrogen ions ($\text{H}^+$) and are proton donors; bases release hydroxyl ions ($\text{OH}^-$) and are proton acceptors.

What building blocks form a triglyceride (neutral fat) molecule?

One molecule of glycerol combined with three fatty acid chains.

What proportion of total body cholesterol is synthesized internally versus acquired through the diet?

Approximately $85\text{\%}$ is synthesized within body tissues, while only $15\text{\%}$ is obtained from diet.

Describe the structural regions of a phospholipid molecule.

It consists of a glycerol backbone attached to a phosphorus-containing polar group ("head") and two nonpolar fatty acid chains ("tails").

How many amino acids make up tissue proteins, and what three structural groups do all amino acids contain?

20 different amino acids; they all contain an amine group ($\text{NH}_2$), an acid group ($\text{COOH}$), and a variable side chain (R group).

What defines the primary, secondary, tertiary, and quaternary levels of protein structure?

Primary is the linear sequence of amino acids; secondary consists of local conformations like \text{\alpha}-helices and pleated sheets; tertiary is the overall folded 3D functional shape; quaternary is the arrangement of multiple folded protein subunits in a multi-subunit complex.

What three chemical components form an adenosine triphosphate (ATP) molecule?

An adenine nitrogenous base, a ribose sugar, and three phosphate groups.

Which nitrogenous base is found in RNA instead of thymine?

Uracil (U).

What are the specific functions of mRNA, rRNA, and tRNA during protein synthesis?

mRNA is a single-stranded copy of a gene that carries instructions to the cytoplasm; rRNA oversees the assembly of the encoded protein at the ribosome; tRNA delivers the required amino acids.

What are the three main types of cell membrane junctions and their primary roles?

Tight (occluding) junctions seal cells to prevent small molecules from leaking between them; desmosomes (anchoring junctions) mechanically attach cells to adjacent cells or ECM; gap (communicating) junctions mediate the direct passage of chemical or electrical signals between cells.

What are the functions of the rough endoplasmic reticulum (RER) and Golgi apparatus in cellular protein production?

The RER synthesizes and folds proteins on its attached ribosomes and packages them into transport vesicles; the Golgi apparatus receives these vesicles, then packages and processes the proteins into secretory vesicles or lysosomes.

What are the respective primary functions of smooth endoplasmic reticulum (SER) and mitochondria?

The SER is the site of steroid synthesis; mitochondria are the sites of ATP formation through nutrient oxidation.

What distinguishes simple diffusion, facilitated diffusion, and filtration?

Simple diffusion moves lipid-soluble or small solutes unassisted down a concentration gradient; facilitated diffusion uses a protein carrier or channel to move lipid-insoluble or large solutes down a gradient; filtration forces water and solutes across a membrane via a hydrostatic pressure gradient.

How many sodium ($\text{Na}^+$) and potassium ($\text{K}^+$) ions are transported by the sodium-potassium pump per ATP molecule consumed?

3 $\text{Na}^+$ ions are ejected out of the cell, and 2 $\text{K}^+$ ions are brought into the cell.

What is the difference between exocytosis and endocytosis, including phagocytosis and pinocytosis?

Exocytosis moves materials out of the cell via membranous vesicles fusing with the plasma membrane; endocytosis engulfs extracellular material into vesicles, divided into phagocytosis ("cell eating") and pinocytosis ("cell drinking").

What creates the resting membrane potential (RMP) of approximately $-70\,\text{mV}$ across cell membranes?

The unequal distribution of $\text{Na}^+$ and $\text{K}^+$ ions across the plasma membrane, leaving the inside of the membrane negatively charged relative to the outside.

What ion shifts cause depolarization and repolarization during an action potential?

Depolarization is caused by the rapid influx of $\text{Na}^+$ into the cell through open sodium channels; repolarization occurs when $\text{K}^+$ channels open and $\text{K}^+$ rushes out of the cell within 1–3 milliseconds.