This document provides an introduction to the endocrine system and hormonal responses to exercise. It discusses the nervous and endocrine systems, the structures of the endocrine system including various glands, and an overview of different types of hormones including proteins, peptides, steroids, and derivatives of tyrosine. It also describes autocrine, paracrine and endocrine signaling and the pathways of action for steroid and protein hormones.

1. Introduction to the
Endocrine System
Hormonal Responses and Adaptation to Exercise

2. Coverage
 Nervous System and Endocrine System
 Structures of the Endocrine system
 Overview of Hormones
 Pathways of Hormone Action

3. Nervous System &
Endocrine System

4. Nervous
System
 The nervous system uses two types of intercellular
communication either by the direct action of an electrical
potential, or in the latter case, through the action of
chemical neurotransmitters such as serotonin or
norepinephrine.
 Neural communication enables body functions that
involve quick, brief actions, such as movement,
sensation, and cognition.

5. Endocrine
System
 The endocrine system consists of cells, tissues, and
organs that secrete hormones as a primary or secondary
function.
 Uses just one method of communication: chemical
signaling.
 These signals are sent by the endocrine organs, which
secrete chemicals—the hormone—into the extracellular
fluid.
 Endocrine signaling requires more time than neural
signaling to prompt a response in target cells, though the
precise amount of time varies with different hormones.
 Endocrine signaling is typically less specific than neural
signaling.

7. Structures of
the Endocrine
 Endocrine gland
 Ductless glands
 Primary function is to secrete hormones into the
surrounding fluid (interstitial fluid, blood).
 Endocrine System:
 pituitary, thyroid, parathyroid, adrenal, and pineal
glands
 Organs with Endocrine Functions:
 hypothalamus, thymus, heart, kidneys, stomach,
small intestine, liver, skin, female ovaries, and male
testes

9. Autocrine &
Paracrine
Signaling
 Autocrine
 Glands secrete hormones to affect self (same cell) into
producing more hormones.
 Interleukin-1
 Paracrine
 Glands secrete hormones to affect neighboring cells, tissue,
and organs.
 Histamine

10. Overview of
Hormones
Types & Functions

11. General
Types/Classes
of Hormones
 Proteins & Peptides
 Including hormones secreted by the anterior and posterior
pituitary gland, the pancreas (insulin and glucagon), the
parathyroid gland (parathyroid hormone), and many others.
 Steroids
 Secreted by the adrenal cortex (cortisol and aldosterone),
the ovaries (estrogen and progesterone), the testes
(testosterone), and the placenta (estrogen and
progesterone).
 Derivatives of the amino acid tyrosine
 Secreted by the thyroid (thyroxine and triiodothyronine) and
the adrenal medullae (epinephrine and norepinephrine).
 There are no known polysaccharides or nucleic acid
hormones.

16. Pathways of
Hormone Action
Steroid and Protein Hormones

17. Steroid
Hormones

18. Protein
Hormones

19. References:
Rice University. Anatomy & Physiology. Openstax
Howley, E., & Powers, S. (2015). Exercise physiology: Theory and application to fitness and
performance (10th ed.). McGraw-Hill Education.
Hall, J. E., & Hall, M. E. (2015). Guyton and hall textbook of medical physiology E-book:
Guyton and hall textbook of medical physiology E-book (13th ed.). Elsevier Health Sciences.