Exam 2: Endocrine System Flashcards by Emily Owens

What happens in a nonneural endocrine cell/what does it look like?

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What happens in a neurosecretory cell/what does it look like?

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What happens in local paracrine and autocrine signals/ what do they look like?

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What is an exocrine? Give examples.

An exocrine is secreted into a free system, as opposed to blood.

Examples:

sweat
tears
bile
mammary glands
poison/venom
spider silk

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chemical signals that carry information from one individual to another member of the same species. These include sex attractants, trail marking compounds, alarm substances, and many other intraspecific messages.

Pheromones

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signals that travel from one animal to some member of a different species. These include defensive signals such as repellents, compounds used to locate suitable host plants, and a vast array of other substances that regulate interspecific behaviors.

allelochemicals

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benefit the sender - such as a repellent, or defensive compound that deters predation (like Cantharidin).

allomones

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benefit the receiver - such as an odor that a parasite uses to find its host.

kairomones

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benefit both sender and receiver - such as plant volatiles that attract insect pollinators.

synomones

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Know this table!

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Synthesized on the rough ER
Stored in vesicles
Leave signaling cell via exocytosis
Soluble in aqueous solutions and travel to the target cell dissolved in the extracellular fluid
Hydrophilic: cannot cross the target cell membrane
Bind to transmembrane receptors
Rapid effects on the target cell

Peptide hormones

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Hydrophobic
Cannot be stored within the cell
Synthesized on demand
Transported to target cell by carrier proteins
Slow effects on the target cell

Steroid Hormones

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Steroid hormones are derived from:

cholesterol

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Describe synthesis of sex hormones

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What are the three classes of steroid hormones? Give examples for each.

Mineralocorticoids:
- electrolyte balance
- ex: aldosterone
Glucocorticoids:
- stress hormones
- ex: cortisol
Reproductive hormones:
- regulate sex-specific characteristics and reproduction
- ex: estrogen, progesterone, testosterone

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Possess amine (-NH2)
Biogenic amines
- ex: acetylcholine, catecholamines (dopamine, norepinephrine, epinephrine), serotonin, melatonin, histamine, thyroid hormones
Diverse effects

amine hormones

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Locations of major endocrine glands

1 - 9

PTPAPTPGH

Pituitary gland
Thyroid gland
Parathyroid glands
Adrenal glands
Pineal gland
Thymus gland
Pancreas
Gonads (Ovaries and Testes)
Hypothalamus

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The hypothalamus sends endocrine signals to the

pituitary gland

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Posterior Pituatary vs. Anterior Pituitary:

Which secretes which hormones?

Posterior Pituitary:

Oxytocin (uterine muscles, mammary glands)
ADH (kidney tubules)

Anterior Pituitary:

TSH → thyroid
ACTH → adrenal cortex
FSH and LH → testes or ovaries
Growth hormone (GH) → entire body
Prolactin (PRL) → mammary glands
Endorphins → pain receptors in brain

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two-lobed organ that secretes nine major hormones

pituitary gland

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posterior lobe (neural tissue) and the infundibulum
- receives, stores, and releases hormones from the hypothalamus

Neurohypophysis

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anterior lobe, made up of glandular tissue
- synthesizes and secretes a number of hormones

Adenohypophysis

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Just understand this diagram.

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Understand the effects of hormones from the anterior pituitary:

TSH

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Understand the effects of hormones from the anterior pituitary: ACTH

Understand the effects of hormones from the anterior pituitary: Growth Hormone

Understand the effects of hormones from the anterior pituitary: LH and FSH

Understand the effects of hormones from the anterior pituitary: MSH in some animals

Understand the effects of hormones from the anterior pituitary: Prolactin

Characteristics of all anterior pituitary hormones:

1. Proteins (or peptides) 2. Act through second-messenger systems 3. Regulated by hormonal stimuli, mostly negative feedback

Hormones of the Anterior Pituitary: * General metabolic hormone * Major effects are directed to growth of skeletal muscles and long bones * Plays a role in determining final body size * Causes amino acids to be built into proteins * Causes fats to be broken down for a source of energy

Growth Hormone

* Antagonistic hypothalamic hormones regulate GH * Which hormone stimulates GH release? * Which hormone inhibits GH release?

* **Growth hormone–releasing hormone (GHRH)** stimulates GH release * **Growth hormone–inhibiting hormone (GHIH)** inhibits GH release

* Triggered by the hypothalamic prolactin-releasing hormone (PRH) * Stimulates and maintains milk production following childbirth * Function in males is unknown

Prolactin (PRL)

* Triggered by hypothalamic corticotropin-releasing hormone (CRH) in a daily rhythm * Regulates endocrine activity of the adrenal cortex

Adrenocorticotropic hormone (ACTH)

* Triggered by hypothalamic peptide thyrotropin-releasing hormone (TRH) * Influences growth and activity of the thyroid gland

Thyroid-stimulating hormone (TSH)

* Regulate hormonal activity of the gonads * Triggered by the hypothalamic gonadotropin-releasing hormone (GnRH) during and after puberty

Gonadotropic hormones

* Stimulates follicle development in ovaries * Stimulates sperm development in testes

Follcle-stimulating hormone (FSH)

* Triggers ovulation of an egg in females * Stimulates testosterone production in males

Luteinizing hormone (LH)

Hormones of the Posterior Pituitary: * Stimulates contractions of the uterus during labor, sexual relations, and breastfeeding * Causes milk ejection in a nursing woman

Oxytocin

Hormones of the Posterior Pituitary: * Inhibits urine production by promoting water reabsorption by the kidneys * In large amounts, causes vasoconstriction leading to increased blood pressure * Also known as vasopressin

Antidiuretic hormone (ADH)

The thyroid gland consists of two lobes and a

connecting isthmus

The thyroid gland is composed of follicles that produce the

glycoprotein thyroglobulin

Colloid (thyroglobulin + iodine) fills the lumen of the follicles in the thyroid gland and is the

precursor of thyroid hormone

Other endocrine cells, the parafollicular cells, produce the hormone:

calcitonin

* Major metabolic hormone * increases rate of energy release from carbohydrates * increases rate of protein synthesis * accelerates growth * Heat production

Thyroid hormone

The thyroid hormone is composed of two active iodine-containing hormones:

* **Thyroxine (T4)**—secreted by thyroid follicles, four iodine atoms, inactive form, 95% of hormone produced * **Triiodothyronine (T3)**—conversion of T4 at target tissues, active form

* Decreases blood calcium levels by causing its deposition on bone * Antagonistic to parathyroid hormone * Produced by parafollicular cells

Calcitonin

The parathyroid glands are tiny masses on the posterior of the thyroid that secrete .

parathyroid hormone (PTH)

* Stimulate osteoclasts to remove calcium from bone * Stimulate the kidneys and intestine to absorb more calcium * Raise calcium levels in the blood

parathyroid hormone (PTH)

Synthesizes and releases steroid hormones called corticosteroids

adrenal cortex

* Different corticosteroids are produced in each of the three layers * Zona glomerulosa: * Zona fasciculata: * Zona reticularis:

* Zona glomerulosa: **mineralocorticoids (chiefly aldosterone)** * Zona fasciculata: **glucocorticoids (chiefly cortisol)** * Zona reticularis: **gonadocorticoids (chiefly androgens)**

Hormones of the Adrenal Medulla: * Produces two similar hormones (catecholamines): * These hormones prepare the body to deal with short-term stress (“fight or flight”) by * Increasing heart rate, blood pressure, blood glucose levels * Dilating small passageways of lungs

* Epinephrine → potent stimulator of the heart and metabolic activities * Norepinephrine → more influential on peripheral vasoconstriction and blood pressure

A triangular gland, which has both exocrine and endocrine cells, located behind the stomach

the pancreas

produce an enzyme-rich juice used for digestion (exocrine product)

acinar cells

what is the function of the pancreatic islets (islets of Langerhans)?

to produce hormones (endocrine products)

* Glucagon * Forces cells to release glucose

Alpha cells in the pancreas

* Insulin * Forces cells to absorb and utilize glucose * Carbohydrate, fat, protein metabolism

Beta cells in the Pancreas

* Somatostatin * Inhibits insulin and glucagon release

Delta cells in pancreas

* loss of the insulin-producing beta cells of the islets of Langerhans * autoimmune disease * leading to a deficiency of insulin * Insulin injections most common treatment, diet, exercise

Type I Diabetes

* More common * due to insulin resistance or reduced insulin sensitivity, and decreased secretion. * Insulin produced, but not recognized * Age-onset (overweight) * Treatment: diet and exercise

Type II Diabetes

* Lobulated gland located deep to the sternum in the thorax, right above the heart * Major hormonal products are **thymopoietins** and **thymosins** * These hormones are essential for the development of the T lymphocytes (T cells) of the immune system

Thymus

* Found on the third ventricle of the brain * Secretes melatonin * Helps establish the body’s wake and sleep cycles * Believed to coordinate the hormones of fertility in humans

Pineal Gland

* Promote normal cell metabolism * Help resist long-term stressors * Released in response to increased blood levels of ACTH

Glucocorticoids (including cortisone and cortisol)

* Help the body resist stress by: * Keeping blood sugar levels relatively constant * Maintaining blood volume and preventing water shift into tissue * decreases protein synthesis * increases fatty acid release * stimulates glucose synthesis from noncarbohydrates

Glucocorticoids (including cortisone and cortisol) (FROM THE ADRENAL CORTEX)

Regulate the electrolyte concentrations of extracellular fluids

Mineralocorticoids (mainly aldosterone)

* most important mineralocorticoid * Maintains Na+ balance by reducing excretion of sodium from the body * Stimulates reabsorption of Na+ by the kidneys * Increases osmolarity of the blood

aldosterone

the shedding of the old cuticle

Ecdysis

The shed “skin” is called an:

exuvium

* The insect is called from apolysis (they are pale in color and soft) * Sclerotization works toward the outside, so delay in hardening

* pharate

The insect gulps air, water and contracts muscles, resulting in the old cuticle being split along a predetermined .

ecdysial line

Brain neurosecretory cells produce , which was the first insect hormone to be discovered!!!!

Prothoracicotropic hormone (PTTH)

* connected to the brain receives the hormone * controls much of metabolism, heart beat, basic bodily functions

Corpora cardiaca (cc) very similar to the hypothalamus in humans

* in the head and thorax are stimulated by PTTH levels. * Produce a hormone called **ecdysone** which stimulates the epidermis to initiate the molting process. Ecdysone travels thru the hemolymph.

Prothoracic glands

* connected to the brain, receives the hormone as well * produces **juvenille hormone (JH)** which inhibits the differentiation to adult. * As long as JH is high, you stay in the juvenile stage, however you may get larger do to molting. * Each stage of growth in an insect is called an **instar.**

Corpora allata (ca)

Understand this chart

1. Insect grows larger, waves of ecdysone tell it to molt. 2. Juvenile hormone produced as well, early on levels are high, telling the insect to stay in juvenile stage. 3. As juvenile continues to age, JH levels drops with each molt (each wave of molting). 4. When JH reaches a very low level, signals to change to adult stage. 5. This may take another molt to change to adult stage, at which point JH is virtually absent.

egg to an immature stage that molts several times to a sexually mature adult; in all cases there is little difference in the appearance of the insect.

Ametabolous

* egg to an aquatic immature stage (naiad), to a sexually mature adult; naiad and adult differ little in morphology, and often to some degree in habitat. * JH production stops in last instar

Hemimetabolous

* egg to a terrestrial immature stage (nymph), to a sexually mature adult; nymph and adult differ little in morphology as well as habitat. * JH production stops in last instar

Paurometabolous

* egg to a larval stage to a pupal stage, to a sexually mature adult; larva and adult differ greatly in appearance and usually habitat. * JH decreases in last instar to produce pupa; JH disappears in pupa

Holometabolous