Human Physiology Vocab 1

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Diffusion

Back 1

the net movement of a certain type of molecule (or atom) that results from the combination of random molecular motion and a concentration gradient. Specifically, net movement tends to go with the concentration gradient (that is, from high to low) due to the higher probability of a molecule moving from a region of higher concentration to one of lower concentration than vice versa.

Front 2

Convection

Back 2

a mass migration of molecules within a fluid (that is, a liquid or gas) that is powered by a pressure gradient

Front 3

Epithelium

Back 3

a sheet-like arrangement of cells, where the cells are held together by strong connections (typically desmosomes).

Front 4

Interstitial Space

Back 4

the space in any animal that is inside (must pass through) an epithelium, but outside any cells.

Front 5

Endoderm

Back 5

the epithelium that lines the gut cavity or gut tube of a two- or three-layered animal.

Front 6

Homeostasis

Back 6

the act of maintaining similar conditions despite constant disruptive fluctuations.

Front 7

Sensor

Back 7

any device that adjusts a processor’s rate as a response to detecting some change in conditions.

Front 8

Counter-Acting Response

Back 8

when a sensor that detects some trend of change initiates rate adjustments that act to reverse the trend.

Front 9

Hormone

Back 9

any chemical signal that uses the circulatory system to travel between the monitor that released it and whatever effectors respond to it.

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Neurotransmitter

Back 10

any chemical signal released from the end of a nerve cell that has a direct effect on whether the postsynaptic cell will fire an action potential.

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Solute

Back 11

any chemical that is dissolved (suspended within) a solvent

Front 12

Osmolarity

Back 12

the osmoles per liter of solution, where an osmole is the total number of particles (in terms of moles) suspended within the solution. (Note: the size of the particle is irrelevant, which means an atomic ion or a very large dissolved molecule both count as one particle.)

Front 13

Buffer

Back 13

omething that minimizes changes in pH by associating with (binding with) hydrogen ions when their concentration increases, and dissociating with (releasing) hydrogen ions when their concentration decreases.

Front 14

Enzyme

Back 14

any protein that acts as a catalyst for a specific chemical reaction.

Front 15

Permease

Back 15

any protein that aids in the movement of a specific type of molecule across a cell membrane.

Front 16

Tight Junction

Back 16

a connection between two cells that forms a sufficiently tight seal that even most small molecules are prevented from moving from one side of an epithelium to the other by leaking through the spaces between cells.

Front 17

Gap Junction

Back 17

small tube like structures made of protein (a channel protein) that create a direct connection between the cytoplasm of adjacent cells.

Front 18

Connective Tissue

Back 18

regions of interstitial space with few cells and lots of extracellular matrix. (Note: the extracellular matrix typically contains a network of molecules involved in providing structural support to the organism.)

Front 19

Higher Phosphorylation Potential

Back 19

a molecule (base-group) that in comparison to another molecule does not hold onto certain phosphates as tightly, so (during a chemical reaction) more readily donates a phosphate (to this other molecule) than accepts a phosphate (from this other molecule).

Front 20

Protein Kinase

Back 20

the generic name given to any of the enzymes that catalyzes the transfer of a phosphate from ATP to a protein.

Front 21

Protein Phosphatase

Back 21

the generic name given to any of the enzymes that catalyzes the transfer of a phosphate from a protein to water.

Front 22

Creatine

Back 22

a molecule with similar phosphorylation potential as ADP that is used to store high-energy (or weakly held) phosphates whenever ATP is currently in excess (by accepting a phosphate to become phosphocreatine) and releasing that stored energy whenever ATP is currently scarce ( by donating the phosphate back to an ADP to form ATP).

Front 23

Deamination

Back 23

when the amine group is removed from a molecule (commonly an amino acid) and converted to ammonia.

Front 24

Metabolic Water

Back 24

he name given to water molecules formed whenever molecular oxygen acts as a final acceptor in a respiratory electron transport chain. In other words, it is the water formed as oxygen accepts electrons (accompanied
by protons, or in total hydrogen atoms) out of the final step of the electron transport chain, which is part of aerobic respiration.

Front 25

Concentration Gradient

Back 25

a change in concentration across distance (In biology, the term is often used to discuss a change in concentration across a membrane).

Front 26

Simple Diffusion

Back 26

net directional movement of some type of molecule across a membrane, where the movement is powered by the presence of a concentration gradient (movement from high to low), and the molecules cross simply because the membrane is permeable to this type of molecule.

Front 27

Facilitated Diffusion

Back 27

net directional movement of some type of molecule across a membrane, where the movement
is powered by the presence of a concentration gradient (movement from high to low), and the molecules cross the membrane with the aid of a channel protein or a permease.

Front 28

Active Transport

Back 28

net directional movement of some type of molecule across a membrane, where the movement goes against a concentration gradient so the movement is powered by a usable energy source supplied by the cell (specifically ATP), and the molecules cross the membrane with the aid of a permease.

Front 29

Secondary Active Transport

Back 29

a two-stage transport mechanism where first a concentration gradient of some chemical (commonly sodium ions) is established by active transport, and then the transmembrane flow of this same chemical
with its concentration gradient is used as the energy source to power transmembrane movement of some other molecule against its concentration gradient.

Front 30

Receptor-Mediated Endocytosis

Back 30

the endocytosis of a certain molecule type occurs due to the molecule binding to a membrane-bound protein , which in turn triggers the chain of events leading to endocytosis.

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Secretory Vesicle

Back 31

a membrane bound compartment within a cell that contains molecules destined to be released outside the cell by exocytosis.

Front 32

Osmosis

Back 32

the diffusion of solvent molecules (water molecules) towards regions of higher osmolarity (hence regions of lower water concentration).

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Tonicity

Back 33

the relative osmolarity of the solution surrounding the cell in comparison with the solution inside the cell.

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Membrane Potential

Back 34

a separation of charge (in the form of different types of ions) between the two sides of a cell membrane.

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Depolarization

Back 35

the reduction of a cell’s membrane potential—that is, a reduction is the overall separation of charge.

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Ligand

Back 36

the generic name for a molecule that has the right shape to bind with a protein.

Front 37

Ligand-Gated Ion Channel

Back 37

(ion-channel-linked receptor, chemically activated ion channel) – a membrane-bound channel protein that opens via the binding of a specific type of molecule (a ligand) to some part of the channel.

Front 38

Enzyme-Linked Receptor

Back 38

a membrane-bound receptor that upon binding to its ligand (on the outside of the cell) activates an enzyme on the cytosolic or inside of the cell that is part of same membrane-spanning complex (as the receptor).

Front 39

G-Protein-Linked Receptor

Back 39

a membrane-bound receptor that upon binding to its ligand (on the outside of the cell) activates a G-protein on the cytosolic or inside of the cell.

Front 40

Second Messenger

Back 40

an intracellular chemical whose formation is triggered by the binding of a ligand to a membrane- bound receptor, and once formed triggers changes (often a whole series of changes) within the workings of the cell.

Front 41

Adenylate Cyclase

Back 41

an enzyme that catalyzes the conversion of ATP to cyclic AMP (cAMP).

Front 42

Phospholipase C

Back 42

an enzyme that catalyzes the splitting of a specific type of phospholipid into IP3 and DAG (both of which act as second messenger molecules).

Front 43

Trophic Hormone

Back 43

a hormone that stimulates the release of another hormone.