Verified Answers
Endocrine System Ans: System composed of various glands that can synthesize and
release special chemical messengers called hormones.
System works closely with the Nervous System and the Immune system to regulate
and integrate body functions.
Functions:
Growth and development
Sexual differentiation
Metabolism
Adaptation to an ever-changing environment
Regulation of digestion
Use and storage of nutrients
Electrolyte and water metabolism
Reproductive functions
,Hormones Ans: Endocrine system uses chemical substances called hormones as a
means of regulating and integrating body functions.
Hormones are thought of as chemical messengers produced to target a specific cell.
They do NOT initiate reactions but function as a modulator of cellular and systemic
responses.
Function as chemical messengers
Move through the blood to distant target sites of action
Or, act more locally as paracrine or autocrine messengers that incite more local
effects
Most are present in body fluids at all times in greater or lesser amounts as needed.
Characteristics
A single hormone can exert various effects in different tissues.
A single function can be regulated by several hormones.
Types of Hormone Actions Ans: Hormones are released in one location but can have
the biologic effect either in that location of release or somewhere else
Endocrine
Paracrine
© Get it right 2025 Getaway - Stuvia US All rights reserved
,Autocrine
Intracrine
Endocrine Ans: Hormones are released in the circulation to act on a target organ
(between remote cells)
Paracrine Ans: Hormones acts locally in cells other than that produced the hormones
Ex: sex steroids in ovary (between local cells)
Hormones acting locally on cells other than those that produced the hormone
For example, the action of sex steroids on the ovary
Autocrine Ans: Hormones exert action on the cells from which they are produced ex:
insulin (on the cell that produced them)
Hormones exerting action on the cells from which they were produced
For example, the release of insulin from pancreatic beta cells can inhibit its release
from the same cells
Intracrine Ans: Hormone action is within the cell that produced the hormone
Mechanisms of Hormone Action Ans: Hormones interact with high-affinity receptors.
These are linked to one or more effector system in the cell.
© Get it right 2025 Getaway - Stuvia US All rights reserved
, Hormone receptors may be located in the plasma membrane of the cell (surface of the
cell) or in the intracellular compartment (inside the cell) of the target cell.
The vesicle mediated pathway Ans: Protein and polypeptide hormones are synthesized
and stored in vesicles in the cytoplasm of the endocrine cell until secretion is required.
Stimulation of the endocrine cell causes the vesicles to move to the cell membrane and
release their hormones.
Non-vesicle mediated pathway Ans: Hormones are synthesized in the smooth
endoplasmic reticulum and released upon synthesis. Ex.: Steroid hormones
Actions of Hormones Released
into the Bloodstream Ans: Circulate as free, unbound molecules
Peptide hormones and protein hormones usually circulate unbound in the blood.
Circulate as hormones attached to transport carriers
Steroid hormones and thyroid hormone are carried by specific carrier proteins
synthesized in the liver.
Intracellular and extracellular mechanisms participate in the termination of hormone
function.
Only free hormones can signal a target cell.
Important Thoughts on Transport
Carrier Hormones Ans: The extent of hormone binding to it's transport carrier
influences the rate at which hormones leave the blood and enter the cells.
Pause and read Transport at the bottom of page 1265 through mid-page 1267.
Understand the correlation between hormone binding and half-life.
© Get it right 2025 Getaway - Stuvia US All rights reserved