Chapter 46: Chemical Signals in Animals

Insulin

________ normally stimulates adipocytes and resting muscle cells to remove glucose from the bloodstream.

Erythropoietin

________ (EPO) is a crucial component in the homeostatic system that maintains the blood oxygen level.

pineal gland

The ________ also regulates sleep- wake cycles.

important estrogen

In humans and other mammals, the most ________ is the molecule estradiol.

Antidiuretic hormone

________ (ADH; also called vasopressin) is a particularly well- studied neuroendocrine signal.

ADH

________ is produced by neurons that have their cell bodies in a brain region called the hypothalamus.

short term reaction

The ________, called the fight- or- flight response, is triggered by the sympathetic nervous system.

Epinephrine

________ and norepinephrine, which differ from one another only by the presence of an additional methyl group on ________, are members of the family of molecules called catecholamines.

Oxytocin

________ stimulates uterine contractions during birthing and subsequent milk release in female mammals.

Estrogens

________ are steroid hormones at direct the development of female secondary sex characteristics in many animal species.

distinct systems

The hypothalamic- pituitary axis forms two anatomically ________ because the pituitary gland has two segments： the anterior pituitary and the posterior pituitary.

neuroendocrine

Even though they are released from neurons, ________ " (nerve- inside- separated) "signals share a key attribute with endocrine signals.

aquatic larva

The process of changing from an immature, ________ to a sexually mature, terrestrial frog, toad, or salamander is an example of metamorphosis.

Organs

________ that secrete a hormone into the bloodstream are called endocrine glands.

Paracrine signals

________ diffuse locally and act on target cells near the source cell.

Positive feedback

________, in contrast, occurs when the product of a process stimulates its production, resulting in greater and greater production of that product.

endocrine signals

The cells that produce ________ may be organized into discrete organs called glands or may be interspersed among the cells of other organs- as are the islets of Langerhans in the pancreas.

negative feedback

In ________, the product of a process inhibits its production.

Exocrine glands

________, in contrast to endocrine glands, deliver their secretions through outlets called ducts into a space other than the circulatory system.

hormone cortisol

The ________ is synthesized in the cortex of the adrenal glands from the steroid cholesterol.

hormone epinephrine

The ________, also known as adrenaline, is synthesized in the medulla of the adrenal glands from the amino acid tyrosine.

pineal gland

The ________ secretes the hormone melatonin, which relays photoperiodic information to the hypothalamus, a brain region at initiates a series of signals directing the production of sex hormones.

pineal gland

In mammals, photoreceptors in the retinas of the eyes send signals to the ________ via a pathway leading through the brain and spinal cord.

46.1 Cell-to-Cell Signaling

An Overview

All three types of signaling pathways

endocrine, neuroendocrine, and neuroendocrine-to-endocrine-are regulated by negative feedback

By purifying components of the liver cell extracts and testing them one by one, researchers eventually found the key ingredient in the activation of phosphorylase

a molecule called cyclic adenosine monophosphate, or cyclic AMP ( cAMP)