Unit 4 Test Flashcards
signal transduction pathway
A series of steps linking a mechanical, chemical, or electrical stimulus to a specific cellular response.
reception
In cellular communication, the first step of a signaling pathway in which a signaling molecule is detected by a receptor molecule on or in the cell.
transduction
The linkage of a mechanical, chemical, or electromagnetic stimulus to a specific cellular response.
response
(1) In cellular communication, the change in a specific cellular activity brought about by a transduced signal from outside the cell. (2) In feedback regulation, a physiological activity triggered by a change in a variable.
ligand
A molecule that binds specifically to another molecule, usually a larger one.
G-protein
A GTP-binding protein that relays signals from a plasma membrane signal receptor, known as a G protein-coupled receptor, to other signal transduction proteins inside the cell.
receptor tyrosine kinases
A receptor protein spanning the plasma membrane, the cytoplasmic (intracellular) part of which can catalyze the transfer of a phosphate group from ATP to a tyrosine on another protein. Receptor tyrosine kinases often respond to the binding of a signaling molecule by dimerizing and then phosphorylating a tyrosine on the cytoplasmic portion of the other receptor in the dimer.
protein kinases
An enzyme that transfers phosphate groups from ATP to a protein, thus phosphorylating the protein.
cascades
A series of chemical reactions during cell signaling mediated by enzymes (kinases), in which each kinase in turn phosphorylates and activates another, ultimately leading to phosphorylation of many proteins.
secondary messenger
A molecule that relays messages in a cell from a receptor to a target where an action within the cell takes place.
cyclic AMP
Cyclic adenosine monophosphate, named because of its ring structure, is a common chemical signal that has a diversity of roles, including as a second messenger in many eukaryotic cells, and as a regulator of some bacterial operons.
amplification
The strengthening of stimulus energy during transduction.
apoptosis
programmed cell death
regulator
An animal for which mechanisms of homeostasis moderate internal changes in a particular variable in the face of external fluctuation of that variable.
conformer
An animal for which an internal condition conforms to (changes in accordance with) changes in an environmental variable.
homeostasis
The steady-state physiological condition of the body.
thermoregulation
The maintenance of internal body temperature within a tolerable range.
endothermic
Referring to organisms that are warmed by heat generated by their own metabolism. This heat usually maintains a relatively stable body temperature higher than that of the external environment.
ectothermic
Referring to organisms for which external sources provide most of the heat for temperature regulation.
negative feedback
A form of regulation in which accumulation of an end product of a process slows the process; in physiology, a primary mechanism of homeostasis, whereby a change in a variable triggers a response that counteracts the initial change.
positive feedback
A form of regulation in which an end product of a process speeds up that process; in physiology, a control mechanism in which a change in a variable triggers a response that reinforces or amplifies the change.
endocrine system
In animals, the internal system of communication involving hormones, the ductless glands that secrete hormones, and the molecular receptors on or in target cells that respond to hormones; functions in concert with the nervous system to effect internal regulation and maintain homeostasis.
nervous system
In animals, the fast-acting internal system of communication involving sensory receptors, networks of nerve cells, and connections to muscles and glands that respond to nerve signals; functions in concert with the endocrine system to effect internal regulation and maintain homeostasis.
endocrine gland
A ductless gland that secretes hormones directly into the interstitial fluid, from which they diffuse into the bloodstream.
hormone
In multicellular organisms, one of many types of secreted chemicals that are formed in specialized cells, travel in body fluids, and act on specific target cells in other parts of the organism, changing the target cells’ functioning.
local regulators
A secreted molecule that influences cells near where it is secreted.
autocrine
Referring to a secreted molecule that acts on the cell that secreted it.
paracrine
Referring to a secreted molecule that acts on a neighboring cell.
insulin/glucagon
lowers blood glucose levels/raises blood glucose level
hypothalamus
The ventral part of the vertebrate forebrain; functions in maintaining homeostasis, especially in coordinating the endocrine and nervous systems; secretes hormones of the posterior pituitary and releasing factors that regulate the anterior pituitary.
pituitary gland
An endocrine gland at the base of the hypothalamus; consists of a posterior lobe, which stores and releases two hormones produced by the hypothalamus, and an anterior lobe, which produces and secretes many hormones that regulate diverse body functions.
thyroid gland
An endocrine gland, located on the ventral surface of the trachea, that secretes two iodine-containing hormones, triiodothyronine (T3) and thyroxine (T4), as well as calcitonin.
