PHYSIOLOGY

4. DAFINITION
The word hormone is derived from the Greek
word bormaein which means to execute or
to arouse. In the classic definition hormones
are secretory products of the ductless
glands, which are released in catalytic
amounts into blood stream and transported
to specific target cells(or organs), where
they elicit physiologic, morphologic and
biochemical responses. The chemical
messengers which perform hormonal
functions are defined as Pic.

6. Endocrine hormones.
These are the chemical messengers
whose function is the transmission of a
molecular signal from a classic
endocrinal cell through the blood
stream to a distant target cell.
Neurocrine hormones.
Neurohormones or peptides are released
from a neurosecretory neuron into the
blood stream and then carried to a
distant target cells Example of such
neurocrine substances are oxytocin
and antidiuretic hormone (ADH).

7. Paracrine hormones.
These are chemical messengers which after
getting secreted by a cell are carried over
short distance by diffusion through the
interstitial spaces (extra cellular fluid) to act
on the neighboring different cell types. For
example, in islets of Langerhans
somatostatin secreted by the delta cells
acts on the alpha and beta cells.
Autocrine hormones.
These refer to those chemical messengers
which regulate the activity of neighboring
similar type of cells. Examples of autocrine
hormones are prostaglandins.

8. Typesofgroupiihormonesbasedonthechemicalnatureof
secondmessengerinvolvedintheirmechanismofaction

9. MCQ
 The following hormones increase the level of
intracellular cAMP except?
 a) vasopressin
 b) glucagon
 c) parathyroid hormone
 d) 1,25-DHCC

10. A. Depending upon the chemical natuere

12. Hormone transport

17. 1. Feedback control

25. SPECIFICITY OF HORMONE ACTION IS BECAUSE OF SPECIFIC
RCEPTORS.

29. The main mechanisms of hormone actions are:

40. Mechanism of action of hormone via
tyrosine kinase activation

42. Mechanism of action of hormone via tyrosine kinase activity: A,
by receptors that possess intrinsic tyrosine activity: and B, by
receptors that do not possess intrinsic tyrosine activity.

44. MEASUREMENT OF HORMONES

46. Enzyme- linked immunosorbent assay
method

48. THE END