Exam 2 - Endocrine System Flashcards
What is Autocrine Signaling?
Made by the cell, but stimulate the same cell, “talking to yourself”
Where is Autocrine Signaling important?
Inflammatory cells
What is Paracrine Signaling?
When cells signal to nearby cells “playing telephone”
What is Endocrine Signaling?
Hormones produced by endocrine glands enter the circulation
What are two important functions of the endocrine system?
Communication and regulation
What is endocrinology?
The study of endocrine glands and hormones
Exocrine glands
Have ducts that allow secretions to empty into a lumen (like the intestine) or onto a surface like the skin
Endocrine glands
Ductless glands that secretes directly into blood vessels
Hormones
Chemical messengers produced by specialized cells
______ __________ of hormones needed to have a large effect on organs and tissues
Low concentration
Properties of the endocrine system (6)
Wireless, chemical signal in the blood, slower acting, long duration, specific receptors, hormone
What stimulates humoral release
Hormones release caused by altered levels of certain critical ions or nutrients
What stimulates neural release
Hormone release caused by neural input
What causes hormonal release
Hormone release caused. By another hormone (a tropic hormone)
An example of humoral stimulus
Stimulus: Low concentrations of Ca2+ in capillary blood
Response: Parathyroid glands secrete parathyroid hormone (PTH), which increases blood Ca2+
An example of neural stimulus
Stimulus: action potentials in preganglionic sympathetic fibers to adrenal medulla
Response: Adrenal medulla cells secrete epinephrine and norepinephrine
An example of hormonal stimulus
Stimulus: hormones from hypothalamus
Response: anterior pituitary gland secretes hormones that stimulate other endocrine glands to secrete hormones
Properties of peptide hormones:
Synthesized as ___________, can travel ________ in the blood, utilize _______ _______, have ________ ________
Preprohormones; freely; second messengers; rapid onset
Properties of steroid hormones
Synthesized from ________, require _______ ________ to travel in the blood, change _________ ________ _______, have _______ onset but have a ________ duration
Cholesterol; carrier proteins; gene expression directly; slower; longer
Amine hormones are ________ from _______
Synthesized; tyrosine
Adrenaline amine hormone properties
Adrenaline - like _______, ________ and ________ ________
Adrenaline- peptides; polar; second messengers
Thyroid amine hormone properties
Thyroid hormones - like ________, ______-______, direct action on _______ _______
Thyroid- steroids; protein-bound, nuclear receptors
Examples of peptide hormones
Insulin, glucagon, prolactin, ACTH, gastric PTH
Examples of steroid hormones
Cortisol, aldosterone, estrogen, progesterone, testosterone
Steroid hormones: a change in mRNA results in a change in ________ _________, this change elicits biological response
Protein production
What are eicosanoids?
Chemical derivatives of long-chain fatty acids
Eicosanoids mostly participate as __________ agents, as they are rapidly metabolized
Paracrine
How do eicosanoids differ from true hormones?
Eicosanoids are produced in small quantities by almost all tissues
Some eicosanoids act as ________ ________
Signaling molecules
Prostaglandins
Thromboxane
Leukotrienes
Target organs
How is wireless communication regulated (3 ways)
Disposal of hormones
Degraded inside the cell after action or excess degraded in the liver and kidneys then excreted via the urinary and biliary system
The effect of a hormone is determined by
Availability of receptors and concentration of the hormone in the blood
Concentration of hormone in the blood is determined by
Rate of release and rate of elimination/removal
Rate of release is determined by
Positive and negative feedback regualtion
Peptide hormones and amines are ______ in _______, ‘docking’ for release requires ________
Stored; vesicles; calcium
Steroid hormones are _____ _______ and must be _________ just prior to release
Not stored; synthesized
Negative feedback regulation
Positive feedback regulation
Examples of negative regulation
Example of positive feedback regulation
