Endocrine System Review

Which organ is considered a "neuroendocrine" organ? [blank_start]hypothalamus[blank_end]

Which organ system works with the endocrine system to control or regulate body function? [blank_start]nervous system[blank_end]

The endocrine system controls, regulates, and maintains [blank_start]homeostasis[blank_end]

What glands have both exocrine and endocrine functions? [blank_start]pancreas[blank_end], [blank_start]gonads[blank_end], [blank_start]placenta[blank_end]

[blank_start]Hormones[blank_end] - travel in blood or lymph over long distances [blank_start]Autocrines[blank_end] - exert effects on same cells that secrete them [blank_start]Paracrines[blank_end] - affect local cells but not those that secrete them

Autocrines and Paracrines are considered part of the endocrine system

What are the three types of chemical messengers? [blank_start]hormones[blank_end], [blank_start]autocrines[blank_end], [blank_start]paracrines[blank_end]

Which cells are affected by hormones?

What are the two main chemical classes of hormones? [blank_start]amino acid-based[blank_end] [blank_start]steroids[blank_end]

What chemical class are most hormones?

Steroids are synthesized from [blank_start]cholesterol[blank_end].

Gonadal (sex) hormones and Adrenocortical hormones are considered what chemical class? [blank_start]steroid[blank_end]

Hormones circulate through blood to all body cells, but only cells with [blank_start]receptors[blank_end] for a specific hormone will respond to that hormone.

The two mechanisms of hormone action are [blank_start]water[blank_end]-[blank_start]soluble[blank_end] hormones and [blank_start]lipid[blank_end]-[blank_start]soluble[blank_end] hormones.

All amino-acid based hormones except thyroid hormone are [blank_start]water-soluble hormones[blank_end].

Steroids and thyroid hormones are [blank_start]lipid-soluble hormones[blank_end].

Characterize the Nervous System vs. Endocrine System: messenger: [blank_start]electrochemical impulses[blank_end] vs. [blank_start]chemical messengers[blank_end] response time: [blank_start]quick[blank_end] vs. [blank_start]slow[blank_end] duration of response: [blank_start]short[blank_end] vs. [blank_start]long[blank_end] target location: [blank_start]local[blank_end] vs. [blank_start]distant[blank_end]

Synthesis/release of most hormones is controlled by [blank_start]negative[blank_end] feedback mechanism.

Amino acid hormones (except thyroid hormones) bind to [blank_start]receptors[blank_end] in the plasma membrane and then act via intracellular [blank_start]second[blank_end] messengers. This is called the [blank_start]Cyclic[blank_end] [blank_start]AMP[blank_end] [blank_start]signaling[blank_end] mechanism.

Cyclic AMP signaling mechanism steps 1. [blank_start]Hormone binds to membr. receptor[blank_end] 2. [blank_start]Recptr binds & actv G protein @ cell mem[blank_end] 3. [blank_start]G protein actv. adenylate cyclase[blank_end] 4. [blank_start]Adenylate cyclase conv ATP to cyclic AMP[blank_end] 5. [blank_start]cAMP activates protein kinases[blank_end] 6. [blank_start]Protein kinases phosphorylate proteins[blank_end]

The Cyclic AMP signaling mechanism has a [blank_start]hormone[blank_end] first messenger and a [blank_start]cAMP[blank_end] second messenger.

The cyclic AMP signaling mechanism starts with a [blank_start]hormone[blank_end] (first messenger) binding to a [blank_start]membrane[blank_end] receptor. The receptor binds and activates [blank_start]G protein[blank_end] at the cell [blank_start]membrane[blank_end]. This activates [blank_start]adenylate cyclase[blank_end] (enzyme), which converts ATP to [blank_start]cyclic AMP[blank_end] (second messenger). The second messenger activates [blank_start]protein kinases[blank_end] which then [blank_start]phosphorylate[blank_end] proteins.

In the cyclic AMP signaling mechanism, each adenylate cyclase generates [blank_start]many[blank_end] cAMP molecules which then activates protein kinases which phosphorylates [blank_start]many[blank_end] proteins triggering a [blank_start]cascade[blank_end] of chemical reactions called the [blank_start]amplification[blank_end] effect.

Action of cAMP is brief because it is rapidly degraded by enzyme [blank_start]phosphodiesterase[blank_end].

It is OK for cAMP to be broken down because of the [blank_start]amplification effect[blank_end].

Intracellular receptors and direct gene activation steps: 1. [blank_start]Diffuse into target cells[blank_end] 2. [blank_start]bind to and actv. intracellular receptor[blank_end] 3. [blank_start]Recp-horm complex enters nucleus[blank_end] & [blank_start]binds to specific region of DNA[blank_end] 4. [blank_start]Binding to DNA "turns on" a gene[blank_end] [blank_start]initiates transcription of DNA to mRNA[blank_end] 5. [blank_start]mRNA exits nucleus & binds to ribosomes[blank_end] 6. [blank_start]mRNA is translated[blank_end] [blank_start]directs protein synthesis on ribosomes[blank_end]

[blank_start]Thyroxin[blank_end] receptors are found on nearly all cells of body and the hormone is the main regulator of cellular [blank_start]metabolism[blank_end].

Target cell activation depends on the three factors: 1. [blank_start]blood levels[blank_end] of hormone 2. [blank_start]number of receptors[blank_end] on or in the target cell 3. [blank_start]affinity of binding[blank_end] between the hormone and receptor

The three types of stimuli that trigger hormone release are: 1. [blank_start]humoral[blank_end] 2. [blank_start]neural[blank_end] 3. [blank_start]hormonal[blank_end]

What is the stimuli? [blank_start]neural[blank_end] - nervous system fibers stimulate adrenal medulla to secrete catecholamines in response to stress [blank_start]humoral[blank_end] - Blood Ca2+ monitored by parathyroid gland (releases PTH when levels are low) [blank_start]hormonal[blank_end] - hypothalamus hormones stimulate release of most anterior pituitary hormones which then stimulate other endocrine glands to release their hormones

What is the cycle which inhibits the release of anterior pituitary hormones due to increasing levels of hormones from the final target organs? [blank_start]hypothalamic[blank_end]-[blank_start]pituitary[blank_end]-[blank_start]target[blank_end] [blank_start]endocrine[blank_end] [blank_start]organ[blank_end] [blank_start]feedback[blank_end] [blank_start]loop[blank_end]

[blank_start]Nervous system[blank_end] can override normal endocrine controls and thus maintain [blank_start]homeostasis[blank_end].

The nervous system will override normal endocrine controls when under [blank_start]severe stress[blank_end]. The [blank_start]hypothalamus[blank_end] and [blank_start]sympathetic[blank_end] nervous system are activated to override insulin control of blood glucose levels. Blood glucose levels rise to be used if needed during fight-or-flight.

Most hormones circulate in the blood as:

Which hormones circulate bound to a protein carrier?

Concentration of circulating hormone reflects the rate of release of the hormone and speed of inactivation and removal from the body.

After hormones have exerted their effects, most hormones are removed from the blood and broken down by the [blank_start]kidneys[blank_end] and [blank_start]liver[blank_end]. The resulting breakdown products are excreted in the [blank_start]urine[blank_end] and [blank_start]feces[blank_end].

Only one hormone may act on the same target cell at the same time.

What are the three types of hormone interaction? 1. [blank_start]permissiveness[blank_end] 2. [blank_start]synergism[blank_end] 3. [blank_start]antagonism[blank_end]

Characterize the following examples: Glucagon from pancreas and epinephrine from adrenal glands cause liver to release glucose to bloodstream - [blank_start]synergism[blank_end] Thyroid hormone is necessary for normal development of reproductive structures - [blank_start]permissiveness[blank_end] insulin lower blood glucose levels while glucagon raises blood glucose levels - [blank_start]antagonism[blank_end]

The pituitary gland (hypophysis) is connected to the hypothalamus by the [blank_start]infundibulum[blank_end].

The posterior pituitary lobe is made of [blank_start]neural[blank_end] tissue containing cells called [blank_start]pituicytes[blank_end]. The anterior pituitary lobe is made of [blank_start]glandular[blank_end] tissue which is a type of [blank_start]epithelial[blank_end] tissue. The tissue contains [blank_start]basophil[blank_end] cells which produce the tropic hormones and [blank_start]acidophil[blank_end] cells which produce non-tropic hormones.

The pituitary gland is located in the [blank_start]hypophyseal[blank_end] [blank_start]fossa[blank_end] of the [blank_start]sella[blank_end] [blank_start]turcica[blank_end] of the sphenoid bone.

The posterior pituitary is considered a true endocrine gland

The posterior pituitary lobe connects to the hypothalamus via the [blank_start]hypothalamic[blank_end]-[blank_start]hypophyseal[blank_end] [blank_start]tract[blank_end].

Steps to release hormones from posterior pituitary: The hypothalamic [blank_start]neurons[blank_end] synthesize [blank_start]neurohormones[blank_end]. They are transported down the [blank_start]axons[blank_end] of the [blank_start]hypothalamic[blank_end]-[blank_start]hypophyseal[blank_end] tract to the posterior pituitary and stored in the [blank_start]axon terminals[blank_end]. In response to hypothalamic neurons firing, [blank_start]action potentials[blank_end] arriving at the posterior pituitary cause the release of the [blank_start]neurohormones[blank_end].

The two neurohormones released by the posterior pituitary are [blank_start]oxytocin[blank_end] and [blank_start]antidiuretic hormone[blank_end] which are [blank_start]amino acid-based[blank_end] hormones.

The anterior pituitary lobe is connect to the hypothalamus which is a [blank_start]vascular[blank_end] connection called the [blank_start]hypophyseal[blank_end] [blank_start]portal[blank_end] [blank_start]system[blank_end].

The hypophyseal portal system consists of a [blank_start]primary capillary plexus[blank_end] located in the [blank_start]infundibulum[blank_end], [blank_start]hypohyseal portal veins[blank_end], and a [blank_start]secondary capillary plexus[blank_end] located in the [blank_start]anterior pituitary lobe[blank_end].

Which gland do the the 6 tropic hormones released from the hypothalamus stimulate? [blank_start]anterior pituitary gland[blank_end]

[blank_start]Osmoreceptors[blank_end] in hypothalamus monitor blood solute (and water) concentration. When there is too much concentrate posterior pituitary secretes [blank_start]ADH[blank_end] (abbreviation) into blood.

Gigantism occurs due to excessive [blank_start]GH[blank_end] (abr) targeting active [blank_start]epiphyseal[blank_end] [blank_start]plates[blank_end] before they close.

Acromegaly is due to an abundance of [blank_start]GH[blank_end] (abr.) and is often caused due to an [blank_start]anterior[blank_end] pituitary [blank_start]tumor[blank_end]. Affects only the [blank_start]hands[blank_end], [blank_start]feet[blank_end], and [blank_start]face[blank_end] due to ephiphyseal plates having already closed.

The [blank_start]anterior pituitary[blank_end] was called the "master endocrine gland" because many of its hormones regulate activity of other endocrine glands.

What disease is indicated by increased urine output, intense thirst, and is premeditated by damage to the head? [blank_start]Diabetes insipidus[blank_end]

What syndrome is marked by retention of fluid, brain edema, headache, and disorientation especially following neurosurgery/general anesthesia, meningitis, hypothalamic injury, or lung cancer? [blank_start]Syndrome[blank_end] of [blank_start]inappropriate[blank_end] [blank_start]ADH[blank_end] [blank_start]secretion[blank_end]

When high concentrations of ADH are released during severe blood loss, blood pressure is [blank_start]raised[blank_end] and [blank_start]vasoconstriction[blank_end] occurs.