Chapter 5 Flashcards
Endocrine signaling involves the
secretion of hormones directly into the bloodstream. The hormones travel to distant target tissues, where they bind to receptors and induce a change in gene expression or cell function.
Peptide hormones are composed of
amino acids and are derived from larger precursor proteins(polypeptides) that are cleaved during post-translational modification.
peptide hormones are all derived from larger precursor polypeptides that are cleaved during post translational modification. these smaller units are transported to the Golgi apparatus for further modifications that activate the hormones and direct them to the correct locations in the cell.
Peptide hormones are ___and cannot ___ through the ___.
polar (charged)
pass
plasma membrane.
Peptide hormones bind to
extracellular receptors, where they trigger the transmission of a second messenger.
Each step of the signaling cascade can induce
amplification of the signal
Peptide hormones exert effects that usually have
rapid onset but are short-lived: Bec these hormones act the secondary messenger cascades, which are transient. It is quicker to turn them on and off, compared w/ steroid hormones, but their effect do not last w/o relatively constant stimulation.
These peptide hormones are water-soluble, so they travel
freely in the bloodstream and do not require a special carrier.
Steroid hormones are derived from ___ and are produced by the ____and _____
cholesterol, gonads, and adrenal cortex
Steroid hormones are minimally
non-polar and can pass through the plasma membrane.
Steroid hormones are little polar but most they are NOT
These (Steroid hormones ) hormones bind to and
One common form of conformational changes is _____?
promote a conformational change in cytosolic (cytosol) or intranuclear (in the nucleus) receptors; the hormone–receptor complex binds to DNA, altering the transcription of a particular gene. Binding of DNA can ether result in increase or decrease transcription of particular genes.
dimerization, or pairing of two receptor-hormone complexes.
Steroid hormones exert effects that usually have
Steroid hormones exert effects that usually have slow onset but are long-lived.
Because these hormones (steroid hormones) are not water soluble they must be?
What about their activeness ?
carried by proteins in the bloodstream to travel around the body.
Hormones are generally inactive while attached to a carrier protein and must dissociate from the carrier to function. levels of carrier proteins can change the levels of active hormone.
Amino acid–derivative hormones are
modified amino acids.
• Their chemistry shares some features with peptide hormones and some features with steroid hormones; different amino acid–derivative hormones share different features with these other hormone classes.
Amino acid–derivative hormones examples
Common examples are epinephrine, norepinephrine, triiodothyronine, and thyroxine.
Hormones can be classified by their
target tissues.
Direct hormones
are secreted and then act directly on a target tissue.
Ex: Insulin released by the pancreas causes increased uptake of glucose by muscles.
Tropic hormones have
req an intermediary to act.
For Ex: GnRH from hypothalamus stimulates LH and FSH. LH then acts on gonads to stimulate testosterone production in the male and estrogen production in females.
GnRH and LH do not cause direct changes in the physiology of muscle, bone, and hair follicles; rather they stimulate the production of another hormone by another endocrine gland that acts on these target tissue.
Endocrine Organs and Hormones START
START
The hypothalamus is the bridge between the
nervous and endocrine systems
release of hormones from the hypothalamus is mediated by a number of factors, including
including projections from other parts of the brain, chemo-and baroreceptors in the blood vessels, and negative feedback from other hormones.
In negative feedback, the final hormone (or product) of a pathway
inhibits hormones (or enzymes) earlier in the pathway, maintaining homeostasis.
The hypothalamus stimulates the?
what’s another name for the pituitary?
What happens once hormones have been released from the hypothalamus?
anterior pituitary gland through paracrine release of hormones into the hypophyseal portal system, which is a blood vessel system that directly connects the hypothalamus with the anterior pituitary.
Hypophysis
Hormones get released from the hypothalamus into this portal bloodstream, they travel down the pituitary talk and bind to receptors in the anterior pituitary, stimulating the release of other hormones.
Gonadotropin-releasing hormone (GnRH) releases ?
Gonadotropin-releasing hormone (GnRH) promotes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
Growth hormone–releasing hormone (GHRH) releases?
Growth hormone–releasing hormone (GHRH) promotes the release of growth hormone.
Thyroid-releasing hormone (TRH) releases?
Thyroid-releasing hormone (TRH) promotes the release of thyroid-stimulating hormone (TSH).
Corticotropin-releasing factor (CRF)
Corticotropin-releasing factor (CRF) promotes the release of adreno-cortico tropic hormone (ACTH).
(PIF(_____) or ______) does what?
Prolactin-inhibiting factor
Dopamine
inhibits the release of prolactin.
Interactions with the posterior pituitary occur via the?
and what hormones are secreted there?
via the axons of nerves projected by the hypothalamus.
Antidiuretic hormone (ADH or vasopressin) and oxytocin are synthesized in the hypothalamus and then travel down these axons to the posterior pituitary, where they are released into the bloodstream.
The anterior pituitary releases hormones in response to
in response to stimulation from the hypothalamus.
Four of these (FSH, LH, ACTH, and TSH) are tropic hormones, while three (prolactin, endorphins, and growth hormone) are direct hormones.
Follicle-stimulating hormone (FSH)
Follicle-stimulating hormone (FSH) promotes the development of ovarian follicles in females and spermatogenesis in males.
Luteinizing hormone (LH)
Luteinizing hormone (LH) promotes ovulation in females and testosterone production in males.
Adrenocorticotropic hormone (ACTH)
Adrenocorticotropic hormone (ACTH) promotes the synthesis and release of glucocorticoids from the adrenal cortex.
Thyroid-stimulating hormone (TSH)
Thyroid-stimulating hormone (TSH) promotes the synthesis and release of triiodothyronine and thyroxine from the thyroid.
Prolactin promotes
milk production.
Endorphins _____ perception of______ and can produce ____.
decrease
pain and can produce euphoria.
Growth hormone (GH)
Growth hormone (GH) promotes growth of bone and muscle and shunts glucose to these tissues. It raises blood glucose concentrations.
The posterior pituitary releases two hormones produced in the hypothalamus.
Antidiuretic hormone (ADH or vasopressin)
Oxytocin
Antidiuretic hormone (ADH or vasopressin) is secreted in response to a
low blood volume or increased blood osmolarity and increases reabsorption of water in the collecting duct of the nephron, increasing blood volume and decreasing blood osmolarity.
Oxytocin is secreted during
Oxytocin is secreted during childbirth and promotes uterine contractions. It also promotes milk ejection and may be involved in bonding behavior. It is unusual in that it has a positive feedback loop, not negative.
The thyroid is located at the
base of the neck in front of the trachea; it produces three key hormones.