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Endocrine System - Nurses Revision

The endocrine system consists of ductless glands that secrete hormones into the bloodstream, influencing target cells and regulating various bodily functions. Key components include the pituitary gland, which is controlled by the hypothalamus, and hormones that maintain homeostasis through feedback mechanisms. Hormones can act locally or at distant sites, and their levels are self-regulating, responding to specific stimuli.

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TAMBAKI EDMOND
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16 views4 pages

Endocrine System - Nurses Revision

The endocrine system consists of ductless glands that secrete hormones into the bloodstream, influencing target cells and regulating various bodily functions. Key components include the pituitary gland, which is controlled by the hypothalamus, and hormones that maintain homeostasis through feedback mechanisms. Hormones can act locally or at distant sites, and their levels are self-regulating, responding to specific stimuli.

Uploaded by

TAMBAKI EDMOND
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Endocrine System - Nurses Revision

REVIEW OF ANATOMY AND PHYSIOLOGY OF


ENDOCRINE SYSTEM
Endocrine system is a system of ductless glands, which secrete
hormones that are pored in the blood stream to be transported to
the target cells.
The endocrine system is composed of the following

Hormones secreted by these glands act on the specific target


tissue away from their site of secretion. Some hormones are
protein in nature while others are not.

They act by interacting with specific cell membrane receptors to


stimulate the intra cellular Adenylyl cyclase system (membrane-
bound enzyme that catalyzes the conversion of Adenosine
triphosphate (ATP)-organic compound that provides energy to
drive many processes in living cells, such as muscle contraction,
nerve impulse to Cyclic adenosine monophosphate (cAMP) –
messenger used for intracellular signal induction, which in turn
forms ATP to stimulate protein synthesis.

Hormones regulate their own production through a feedback


(negative feedback mechanism) system where the increase in
concentration of the hormone suppresses its own production.

Pituitary gland
The pituitary gland secretes hormones like; (Anterior lobe)

The Posterior lobe secretes

Secretion of the anterior lobe is under the control of


Hypothalamus which secretes regulatory hormones.

Growth hormone stimulates muscular and skeletal growth either


by regulating synthesis of somatomedins by the liver or by
directly stimulating incorporation of amino acids into proteins.
Hypoglycemia is a potent stimulant of growth hormone release;
obesity blunts its release.
Excess secretion of growth hormone after epiphyseal fusion
produces acromegaly where as before epiphyseal fusion
causes gigantism

Image showing hormones produced by the anterior lobe.


Overview of the Endocrine System
The endocrine system consists of glands widely separated from
each other with no physical connections . Endocrine glands are
groups of secretory cells surrounded by an extensive network of
capillaries that facilitates diffusion of hormones (chemical
messengers) from the secretory cells into the bloodstream. They
are commonly referred to as ductless glands because hormones
diffuse directly into the bloodstream. Hormones are then carried
in the bloodstream to target tissues and organs that may be
quite distant, where they influence cellular growth and
metabolism.

Homeostasis of the internal environment is maintained partly by


the autonomic nervous system and partly by the endocrine
system. The autonomic nervous system is concerned with rapid
changes, while endocrine control is mainly involved in slower and
more precise adjustments.
Although the hypothalamus is classified as a part of the brain
rather than an endocrine gland, it controls the pituitary gland and
has an indirect effect on many others.

The ovaries and the testes secrete hormones associated with


the reproductive system after puberty. The placenta that
develops to nourish the developing fetus during pregnancy also
has an endocrine function. In addition there are also other
hormones that do not travel to remote target organs but act
locally.

Overview of hormones
When a hormone arrives at its target cell, it binds to a specific
receptor, where it acts as a switch influencing chemical or
metabolic reactions inside the cell.

The level of a hormone in the blood is variable and self-


regulating within its normal range. A hormone is released in
response to a specific stimulus and usually its action reverses or
negates the stimulus through a negative feedback mechanism.
This may be controlled either indirectly through the release of
hormones by the hypothalamus and the anterior pituitary gland,
e.g. steroid and
thyroid hormones, or directly by blood levels of the stimulus, e.g.
insulin and glucagon.

The effect of a positive feedback mechanism is amplification of


the stimulus and increasing release of the hormone until a
particular process is complete and the stimulus ceases, e.g.
release of oxytocin during labour

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