Biology 1107 Exam 3

Signaling Cell

A cell that releases/secretes signaling molecules

Signaling Molecule

A substance that is released by a signaling cell; acts as a carrier of information; also known as a first messenger or ligand

Receptor Protein

The molecule on the responding cell that binds to the signaling molecule

Responding Cell

The cell that receives information from the signaling molecule

Receptor Activation

The ‘turning on’ of a receptor, which often occurs when a signaling molecule binds to a receptor on a responding cell and triggers a change in the receptor’s shape

Signal Transduction

The process in which an extracellular molecule acts as a signal to activate a receptor, which transmits information to the cell through the cytoplasm

Response

A change in cell behavior, such as division, DNA replication, DNA expression, protein synthesis, change in enzyme activation, motility, etc, following a signal

Termination

In cell communication, the stopping of the response of a cell triggered by a signal

Endocrine Signaling

Long-distance signaling by molecules that travel through the bloodstream

Paracrine Signaling

Signaling by a molecule that travels a short distance to the nearest neighboring cell to bind its receptor and lead to a response

Autocrine Signaling

Signaling between different parts of the same cell; the cell is both the signaling cell and the responding cell

Contact-Dependent Signaling

Signaling that involves direct contact between two cells, typically a ligand on one cell with a receptor on the other cell

Second Messenger

An intermediate, cytosolic signaling molecule that transmits signals from a receptor to a target within the cell; produced downstream of receptor activation

Essential Nutrients

Nutrients required for life that cannot be synthesized by the organism; include vitamins, some amino acids, fatty acids, and dietary minerals

Essential Amino Acid

An amino acid that cannot be synthesized by cellular biochemical pathways and must be obtained through food instead

Dietary Minerals

In animals, a chemical element other than carbon, hydrogen, oxygen, or nitrogen that is required in the diet and must be obtained in food

Vitamins

Organic molecules that are required in very small amounts in the diet

Amylase

An enzyme that breaks down starch; produced by the salivary glands and the pancreas

Lipase

A type of enzyme produced by the tongue, stomach, and pancreas that breaks apart lipids, thus enabling their more effective digestion

Gastrin

A peptide hormone produced in the stomach that stimulates cells lining the stomach to increase their production of HCl

Pepsinogen

An enzyme produced by chief cells in the gastric pits of the stomach

Pepsin

An enzyme produced by the interaction between pepsinogen and HCl in the stomach that breaks down proteins

Trypsin

A digestive enzyme produced by the pancreas that breaks down protein

Secretin

A hormone released by cells lining the duodenum in response to the acidic pH of the stomach contents entering the small intestine and that stimulates the pancreas to secrete bicarbonate ions

Bile

A fluid produced by the liver, stored in the gallbladder, and released into the small intestine that aids in fat digestion by emulsifying lipids in food

Cholecystokinin

A peptide hormone that causes the gallbladder to contract and release bile into the duodenum

Homeostasis

The active regulation and maintenance of a stable internal physiological state in the face of a changing internal environment

Negative Feedback

A process in which the output or product of a pathway opposes the initial stimulus, so that steady conditions are maintained; often underlies homeostasis in a cell or organism

Set Point

A steady-state value in homeostatic regulation