ANHB1102 Study Guide - Final Guide: Parathyroid Gland, Triiodothyronine, Blood Sugar
3 Jun 2018
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TOPIC EIGHT: Endocrines and Homeostasis
Homeostasis:
Homeostasis can be defined as the maintenance of a constant internal
environment despite variable external environments. Homeostasis can have
short term (minute-to-minute), medium term (hours-to-days) or long term
(months-to-years) effects on the human body.
Homeostasis requires communication and this occurs through both nervous and
endocrine input. The nervous system communicates and regulates homeostasis
through action potential while endocrine organs will secrete organs.
Hormones:
Hormones are ligands that to bind specific receptors on target organs. There are
two classes of hormones – steroid and peptide hormones.
Peptide hormones bind to specific
receptors on the cell membrane, and
their signals are mediated via second
messengers. Second messenger systems
are made up of G proteins that activate a
cascade of intracellular mechanisms that
change the calcium concentration of a
cell. This change in calcium
concentration will alter the function of
the cell, for example, it will activate
specific enzymes.
Steroid hormones are lipophilic with a
small molecular weight, being able to
pass directly into a cell without the use
of second messengers. Steroid hormones
can access the nucleus to bind to its
specific receptor through molecular
chaperones that disengage when the
hormone binds to its receptor. When the
receptor-hormone complex is achieved a
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Document Summary
Homeostasis can be defined as the maintenance of a constant internal environment despite variable external environments. Homeostasis can have short term (minute-to-minute), medium term (hours-to-days) or long term (months-to-years) effects on the human body. Homeostasis requires communication and this occurs through both nervous and endocrine input. The nervous system communicates and regulates homeostasis through action potential while endocrine organs will secrete organs. Hormones are ligands that to bind specific receptors on target organs. There are two classes of hormones steroid and peptide hormones. Peptide hormones bind to specific receptors on the cell membrane, and their signals are mediated via (cid:494)second messengers(cid:495). Second messenger systems are made up of g proteins that activate a cascade of intracellular mechanisms that change the calcium concentration of a cell. This change in calcium concentration will alter the function of the cell, for example, it will activate specific enzymes.
