Bio Chapter 45

Steroids

Receptors

False; Lipid-insoluble hormones cannot cross the plasma membrane and get into the cell, so they must bind to receptors on the cell surface and transduce their signals through signal transduction pathways.

They act by affecting the transcription of genes

Zinc finger; A zinc finger is a distinctive DNA-binding domain on some hormone receptors that is exposed when hormone-receptor complexes are formed.

It binds to and activates protein kinase A, which then phosphorylates other enzymes; cAMP binds to and activates protein kinase A, which then phosphorylates other enzymes in the signal transduction pathway.

False; Only low concentrations of hormones are needed in the bloodstream to activate a signal transduction pathway, which works by producing second messengers inside the cell that amplify the hormonal signal.

Association with a cell's plasma membrane

Epinephrine and oxytocin

nonsteroid hormones act via signal transduction pathways; steroid hormones do not act via signal transduction pathways

Estrogen

they turn genes on or off and it takes time for gene products to build up or become depleted

The nucleus; they effect transcription

each set of target cells has different receptor-transduction mechanisms; Look at the epinephrine example in your text. That hormone can trigger different responses in different target cells. Epinephrine can trigger vasodilation responses (blood vessels in skeletal muscles used for fight-or-flight) and vasoconstriction responses (gut vasculature) in an emergency that evokes its secretion.

high levels of ecdysteroids and reduced levels of juvenile hormone; The ecdysteroids are produced by the prothoracic gland and the juvenile hormone is secreted by the corpora allata.

lipid-soluble hormones bind to an intracellular receptor and this hormone-receptor complex binds to DNA; Most water-soluble signals bind to plasma membrane proteins, initiating signal-transduction pathways. In contrast, the lipid-soluble hormones enter target cells and bind with intracellular receptors; the hormone-receptor complexes act as transcription factors, thus altering gene expression.

the physical sensation of the baby sucking at the nipple; The milk-release response system was given as an example of a neuroendocrine pathway with positive feedback leading to milk release from the nursing mother to the sucking baby. The "neuro" part includes the baby's activation of the mother's mechanoreceptor neurons in the breast.

releases one hormone that reduces glucose levels in the blood and another that increases them; The counter-regulatory hormones and their actions are insulin, which decreases glucose levels in the blood, and glucagon, which increases glucose levels in the blood.

Type I diabetes mellitus; Type I diabetes mellitus is also known as childhood-onset diabetes. Hypoactivity of the pancreas' secretion of insulin disturbs the homeostasis of glucose levels in the blood, and these are corrected by administering injections of insulin.

They release hormones into the bloodstream for distribution around the body

True

Neurosecretory cells produce hormones that are stored in the anterior pituitary; This statement is false; neurosecretory cells produce hormones that are stored in the posterior pituitary.

True; The pancreas produces two hormones, insulin and glucagon, which work together to maintain the homeostatic levels of glucose in the blood.

The hypothalamus directs the anterior pituitary to produce hormones that then stimulate or inhibit the production of these hormones; The hypothalamus directs the anterior pituitary to produce hormones that regulate other hormones in a variety of endocrine organs, including the thyroid gland and ovaries.

Aldosterone produced by the adrenal glands controls the reabsorption of sodium ions by the kidneys; The adrenal glands sit atop the kidneys and secrete a variety of hormones, including aldosterone, which controls the reabsorption of sodium ions by the kidneys.

Pituitary gland

Hypothalamus; The hypothalamus secretes both releasing and inhibiting hormones

E and NRE

Glucocorticoids; in response to stress, ACTH stimulates the adrenal cortex to secrete glucocorticoids.

Androgens (testosterone)

Antidiuretic hormone (ADH)

Calcitonin; Parathyroid hormone increases blood calcium levels; calcitonin lowers blood calcium levels

Luteinizing hormone (LH)

Prolactin; Prolactin, secreted by the anterior pituitary, stimulates milk production by the mammary glands.

their requirement for travel through the bloodstream.

High insulin, low glucagon