Chapter 16-Endocrine System Flashcards
Mechanisms for Intercellular Communication
Direct communication Paracrine Communication Autocrine communication Endocrine communication Sympathetic communication
Explain direct communication
Transmitted through gap junctions
Chemical signals are ions, lipid-soluble
Distributed to adjacent cells via connexons
Explain paracrine communication
Transmitted via extra cellular fluid
Chemical signal are paracrines
Limited to local area and cells with proper receptors
Explain autocrine communication
Transmitted via extra cellular fluid
Chemical signals are autocrines
Distributed to the cell that actually secretes the chemical signal
Explain endocrine communication
Transmitted via bloodstream
Chemical signal : hormones
Distributed to target cells with proper receptors
Explain sympathetic communication
Transmitted via neurotransmitters across synapses
Distributed to very specific area with proper receptors.
How are the endocrine and nervous systems similar?
Both release chemicals to bind to receptors on target cells.
They share common chemical messengers (like E and NE)
Both mainly use negative feedback
Both want to preserve homeostasis by regulating activities of other cells organs tissues and systems
What are the three chemical structures of hormones?
Acid derivatives
Peptide hormones
Lipid derivatives
What group of hormones are considered acid derivatives? Give an example of each.
Thyroid hormones (T4) Catecholamines (E) Tryptophan derivatives (Melatonin)
Explain peptide hormones
Synthesized as prohormones
Short polypeptide chains of amino acids (like ADH) to small peptones like insulin.
What is a pro hormone
Inactive precursor molecules that are converted to active hormones
What organs or glands secrete polypeptide hormones?
Hypothalamus Thymus Heart Digestive Tract Pancreas Pituitary Glans
Glycoproteins are considered peptide hormones. Describe them and give examples.
They are polypeptides with carb side chains that function as hormones.
Examples: TSH, LH, FSH
Explain lipid derivatives
Carbon rings and side chains built either from eicosanoids (fatty acids) or cholesterol (sterilize hormones
Eicosanoids
Paracrines that coordinate cellular activities and affect Enzymatic processes
Leukotriens
An eicosanoid that has a secondary role as a hormone
Prostaglandins
A second group of eicosanoids involved in coordinating local cellular activities. (Proglandin E)
What organs release Steroid Hormones?
Reproductive organs
Cortex of adrenal glands
Kidneys
What steroid hormone do reproductive organs release?
Androgens (male)
Estrogen and progesterone (female)
What steroid hormone does the cortex of the adrenal gland release?
Corticosteroids
What steroid does the kidneys release?
Calcitriol
Why do steroids remain in circulation longer than secreted peptide hormones?
Because steroids are bound to specific transport proteins in blood.
What is the endocrine system
Organs whose primary function is the production of hormones or paracrines
What are the primary organs in the endocrine system?
Hypothalamus Pituitary gland Thyroid gland Parathyroid Adrenal gland Pancreas Pineal gland
Purpose of hypothalamus
“Control center”
Fluid Balance
Muscle contraction
Controls hormone secretion of anterior lobe pituitary gland
What hormones are produced in hypothalamus?
Antidiuretic (ADH)
Oxytocin (OXT)
Regularities Hormones
What pituitary lobe does ADH and OXT travel to from hypothalamus?
Posterior lobe
What pituitary lobe does regulatory hormones From hypothalamus travel?
Anterior lobe
What are fenestrated capillaries?
Vessles that allow relatively large molecules to enter or leave the blood stream.
Hypophyseal Portal System
Portal system from hypothalamus to pituitary gland.
How do regulating hormones get from hypothalamus to pituitary gland arteriorlobe.
Via hypophyseal portals
What are two classes of regulatory hormones?
Releasing Hormones(RH) Inhibiting hormones (IH)
What are releasing hormones
Hormones that stimulate synthesis and secretion or one or more hormones in the anterior lobe
What are inhibiting hormones?
Prevents synthesis and secretion of hormones from the anterior lobe.
Purpose and functions of the pituitary gland
Direct chemicals from hypothalamus to other glands thereby regulating exocrine activities of glands.
What are the two lobes of the pituitary gland?
The anterior and posterior lobe
How many tropic hormones does the anterior lobe produce
7
How many hormones does the anterior lobe produce
2
What are tropic hormones?
Hormones that “turn on” endocrine glands or support the function of other organs
What is another name for the pituitary gland ?
Hypophysis
Where is the pituitary gland located?
Within the shell turcica (a small depression in the sphenoid bone)
What is another name for the anterior lobe of the pituitary gland?
Adenohypophysis
What kind of cells do the anterior lobe of the pituitary gland contain?
Endocrine cells
What’s another name for the posterior lobe of the pituitary gland?
Neurophypophysis
What kind of cells does the posterior of the pituitary contain?
Axons of hypothalamic neurons
What hormones are produced in the anterior lobe of the pituitary gland?
TSH (thyroid stimulating hormone) PRL (prolactin) FHS (follicle stimulating hormone) LH (Luteinizing hormone) ACTH (adrenocorticotropic hormone) GH (growth hormone) MSH (melanocyte-stimulating hormone)
What hormones are in the posterior lobe of the pituitary gland?
ADH
OXT
What does TSH (thyroid Stimulating hormone) target?
Thyroid gland to trigger release of thyroid hormones.
How is TSH released?
It is released in response to thyrotropin-releasing hormone (TRH) coming from hypothalamus.
What cells does ACTH target?
The cells in the cortex or the adrenal glands
What does ACTH do?
Simulate release of steroid hormones by adrenal cortex
How is ACTH released?
From corticotropin-releasing hormone (CRH) from hypothalamus
What are gonadotropins?
Hormones that regulate the activity of gonads.
What are the two gonadotropins?
FSH (follicle stimulating hormone)
LH (luteinizing hormone)
What is the purpose of FHS
Promotes ovary follicle development
Works with LH stimulate secretion of estrogen.
Promotes maturation of sperm.
What is the purpose of LH (luteinizing hormone)?
Induces ovulation
Promotes secretion of estrogens and pro estrogens
Promotes secretion of androgens (like testosterone)
What is the purpose of PRL (prolactin)?
Stimulate mammary gland development
Stimulates milk production
What is the purpose of MHS (melanocyte stimulating hormone?
Produce melanin
