Pendahuluan
1.Ruanglingkup Endokrinologi
2.Penggolongan hormon
3.Mekanisme umum biosintesis hormon
4.Mekanisme umum kerja hormon
Ruanglingkup
Endocrinology = a course about biological
communication systems and information transfer
between cells and tissues .
• Membahas tentang konsep-konsep
endokrinologi, biosintesis, mekanisme kerja dan
metabolisme hormon; mekanisme umpan balik,
koordinasi dan integrasi sistem endokrin pada
hewan dalam proses perkembangan,
pertumbuhan, reproduksi dan osmoregulasi;
interaksi antara faktor-faktor lingkungan dengan
sistem endokrin.
The Endocrine System
• This system is subject to complex regulatory
mechanisms that govern hormone synthesis,
release, transport, metabolism and delivery to the
interior of the target cells, and expression and
activity of the hormone receptor itself and its
downstream signaling machinery. The endocrine
system also has complex relationships with the
other major system of communication between
cells, the nervous system, as well as with the
immune system. It exerts widespread effects on
development, growth, and metabolism.
Human Endocrine Organs
In the brain:
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Anterior pituitary gland produces corticotropin (ACTH), thyroid-stimulating hormone (TSH), luteinizing
hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), and prolactin (PRL);
Posterior pituitary gland produces antidiuretic hormone (ADH) and oxytocin;
Hypothalamus produces releasing and inhibitory factors that regulate secretion of the anterior pituitary
hormones;
Pineal gland produces melatonin.
In the periphery
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Thyroid gland (thyroid hormones),
Parathyroid gland (parathyroid hormone [PTH]),
Adrenal gland (corticosteroids, epinephrine),
Ovaries and testis (sex steroids), and
Pancreas (insulin, glucagon and somatostatin).
Organs that are not traditionally considered to be part of the endocrine system also produce hormones.
• Kidney produces renin that converts angiotensinogen to angiotensin I and erythropoietin that stimulates
blood cell production.
• Adipose tissue produces several hormones, including leptin, an important mediator of body weight, and
resistin, which regulates sensitivity to insulin and may be involved in the pathology of type 2 diabetes.
• Heart produces natriuretic peptides. Some molecules traditionally thought to be metabolic
intermediates, such as fatty acids and bile acids, are now known to function as hormones.
Pusat Endokrin pada
Serangga (After Gullan
and Cranstorn 2000)
Elements of an Endocrine System
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Sender = Sending Cell
Signal = Hormone
Nondestructive Medium = Serum & Hormone Binders
Selective Receiver = Receptor Protein
Transducer = Transducer Proteins & 2ndary
Messengers
• Amplifier = Transducer/Effector Enzymes
• Effector = Effector Proteins
• Response (2ndary signal) = Cellular Response (2ndary
hormones)
Hormone
• A molecule that functions as a message within an
organism; its only function is to convey
information.
• Because of this function, physical descriptions of
a chemical suspected of being a hormone are
inadequate to indicate the molecule's role in a
biological system. A molecule is a hormone only
when described in the context of its role in a
biological communication system. Definition of a
hormone requires testing of that molecule in a
biological response system, running a bioassay.
Chemical Composition of Hormones
Target Organs
• Target organs mount a response to a given hormone. They must
express an appropriate cognate hormone receptor protein and
molecules that mediate the receptors' downstream effects.
Hormone Receptors
• Hormone receptors are proteins with bifunctional properties of
recognition of the hormone (ie, ability to distinguish the hormone
from other molecules to which they are exposed) and
transduction of the information from binding to downstream
receptor effects. The hormone acts as an allosteric effector that
alters receptor conformation, and this conformational alteration
transmits (transduces) binding information into postreceptor
events that influence cellular function. Some hormones (eg,
insulin, GH, PRL, leptin, catecholamines) bind cell surface
receptors, whereas others (eg, steroids, thyroid hormones) bind
intracellular receptors that act in the nucleus. Some hormones
(eg, estrogens and progestins) bind multiple receptors, which are
present on both the cell surface and inside the cell.
Komunikasi
Antar Sel
Kerja sebuah sinyal dimulai
ketika sinyal tersebut
berikatan dengan sebuah
reseptor spesifik. Protein
reseptor itu bisa tertanam di
dalam membran plasma sel
target itu atau bisa juga
berada di dalam sel target itu.
Forms of Intercellular Communication
1. Endocrine: secretion of a hormone by one cell
with transmission via the blood, lymph, or
intercellular fluid to a second, target, cell.
2. Paracrine: secretion of a hormone by one cell
with transmission via intercellular fluid to a
second, nearby cell.
3. Autocrine: secretion of a hormone by one cell
with reception and response by the same cell.
4. Pheromonal: secretion by one organism and
sensation and response by a second.
• http://highered.mcgrawhill.com/sites/0072943696/student_view0/ch
apter10/animation__mechanism_of_steroid_
hormone_action__quiz_1_.html