Ch 5 The Endocrine System

glands

organs in the endocrine system that secrete hormones

hormones

molecules that are secreted directly into the bloodstream to distant target tissues

peptide hormones

made up of amino acids; they can be really small or really large; they are charged so they can’t pass through the cell membrane; must bind to an extracellular receptor; rapid effects, but short lived

first messenger

the name for a peptide hormone because it cannot pass through the cell membrane

second messenger

the second signal that is initiated after the first messenger binds to a receptor

signaling cascade

the connection between the hormone at the surface and the effect brough about by second messengers within the cell

amplification

making a signal larger in intensity because, for example, one hormone may bind to multiple receptors which may activate multiple enzymes… so on and so on

cAMP, IP₃, and calcium

What are some common examples of second messengers?

steroid hormones

derived from cholesterol and produced by gonads and adrenal cortex; can easily cross the cell membrane; slower effects, but longer lived; acts directly on DNA

dimerization

pairing of two receptor-hormone complexes

albumin

an example of a protein that carries a steroid hormone around in the bloodstream because steroid hormones are nonpolar; found in egg whites

amino acid-derivative hormones

less common than peptide and steroid hormones; epinephrine, norepinephrine, triiodothyronine, and thyroxine are examples of this

catecholamines

epinephrine and norepinephrine; they bind to G protein-coupled receptors

direct hormones

hormones that are secreted and then act directly on a target tissue

tropic hormones

hormones that require an intermediary to act (gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH))

the brain and anterior pituitary gland

Where do tropic hormones usually originate?

by modifying amino acids (ex: adding iodine to tyrosine)

How are amino acid-derivative hormones made?

hypothalamus

an organ in the endocrine system that regulates the pituitary gland through paracrine release of hormones into a portal system that connects the two

hypophyseal portal system

a blood vessel system that directly connects the hypothalamus with the anterior pituitary

hypophysis

What is another name for the pituitary?

pituitary stalk

hormones travel through the ____________ after they are released from the hypothalamus into the portal bloodstream and are ready to bine to receptors in the anterior pituitary

release of CRF from hypothalamus stimulates release of ACTH in anterior pituitary, which stimulates release of cortisol in adrenal cortex

What is the pathway for making cortisol?

axes

a three organ system that regulates release of stuff (HPA axis = hypothalamus-pituitary-adrenal _______)

oxytocin

hormone produced by hypothalamus and released by posterior pituitary that stimulates uterine contractions during labor and milk letdown during lactation

antidiuretic hormone (ADH) (vasopressin)

a hormone released by the hypothalamus into the posterior pituitary to regulate the body’s water balance by signaling the kidneys to reabsorb water

What are the seven products that the anterior pituitary produces and secretes?

1. Follicle-stimulating hormone (FSH)

2. Luteinizing hormone (LH)

3. Adrenocorticotropic hormone (ACTH)

4. Thyroid-stimulating hormone (TSH)

5. Prolactin

6. Endorphins

7. Growth hormone (GH)

FLAT PEG is the mnemonic, where FLAT is the tropic hormones and PEG is the direct hormones

What are the four tropic hormones that the hypothalamus secrets?

1. Gonadotropin-releasing hormone (GnRH)

2. Growth hormone-releasing hormone (GHRH)

3. Corticotropin-releasing factor (CRF)

4. Thyroid-releasing hormone (TRH)

prolactin

secreted by the anterior pituitary gland that stimulates milk production in the mammary glands

decreases its production

Does dopamine increase or decrease prolactin production?

endorphins

a product of the anterior pituitary that decreases the perception of pain

growth hormone (GH)

a product of the anterior pituitary that promotes the growth of bone and muscle

gigantism

a condition caused by excess release of GH released in childhood

dwarfism

a condition caused by low release of GH during childhood

acromegaly

a condition where too much GH is secreted during adulthood

positive feedback in regards to uterine contractions

What type of feedback is oxytocin release?

False: The hypothalamus PRODUCES these hormones, but they are simply RELEASED in the posterior pituitary

True or False: The posterior pituitary produces the hormones ADH and oxytocin.

thyroid-stimulating hormone

the hormone that controls the thyroid

setting basal metabolic rate and promoting calcium homeostasis

What are the two functions of the thyroid?

triiodothyronine (T₃) and thyroxine (T₄)

hormones produced by the iodination of the amino acid tyrosine in the follicular cells of the thyroid

follicular cells

cells found in the thyroid that produce T₃ and T₄

hypothyroidism

condition caused by low levels of iodine or inflammation of the thyroid where not enough thyroid hormones are released

cretinism

a condition where low levels of thyroid hormones will cause children to have intellectual disabilities and developmental delay

hyperthyroidism

a condition of excess thyroid hormone

C-cells (parafollicular cells)

one of the two cell types found in the thyroid that produces calcitonin

calcitonin

a hormone released by the thyroid that tones down calcium levels in the blood; is antagonistic to PTH

parathyroid hormone (PTH)

the hormone produced by the parathyroid that raises calcium levels; is antagonistic to calcitonin

vitamin D

required for the absorption of calcium and phosphate in the gut

adrenal glands

located on top of the kidneys

adrenal cortex

found in one of each of the adrenal glands; secretes corticosteroids

glucocorticoids

one of the three classes of corticosteroids secreted by the adrenal cortex; they regulate glucose levels and affect protein metabolism; the two types of glucocorticoids are cortisol and cortisone

mineralocorticoids

one of the three classes of corticosteroids that are used in salt and water homeostasis; aldosterone is an example

cortical sex hormones

one of the three classes of corticosteroids that the adrenal glands secrete; includes androgens and estrogens

epinephrine and norepinephrine

the two sympathetic hormones that the adrenal medulla produces

islets of Langerhans

the location of hormone-producing cells in the pancreas

glucagon

the hormone that alpha cells release in the islets of Langerhans in the pancreas

insulin

the hormone that beta cells release in the islets of Langerhans in the pancreas

somatostatin

the hormone that delta cells release in the islets of Langerhans in the pancreas

glucagon

released by alpha cells in the islets of Langerhans in the pancreas. Is secreted when glucose is low

insulin

released by beta cells in the islets of Langerhans in the pancreas when glucose levels are high

hypoglycemia

low blood glucose concentration

hyperglycemia

high blood glucose concentration

polyuria

increased frequency of urination

polydipsia

increased thirst

Type 1 diabetes mellitus

autoimmune destruction of the beta cells in the pancreas which causes low insulin production

somatostatin

secreted when high blood gluose and amino acid concentrations; is an inhibitor of both insulin and glucagon secretion; produced by the delta cells of the islets of Langerhans in the pancreas

pineal gland

organ in the endocrine system located deep within the brain that secretes the hormone melatonin

circadian rhythms

controlled by the secretion of melatonin