BIOL 1120 Lecture Notes - Lecture 7: Blood Sugar, Antidiuretic, Ketone

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31 May 2016
Chapter 45: The Endocrine System
I. The Endocrine System
A. A system of hormones and the cells that secrete (endocrine glands) and receive them (target cells).
B. Gland types :
1. Endocrine Glands (ductless glands) - hormones diffuse from gland cells directly into the capillaries (Fig. 45.2,
p. 939)
2. _______________ (duct glands) – secretions are released through a duct that leads to the outside of the body
C. Hormones and Other Signaling Molecules
1. Signaling molecules are hormones and secretions that can bind to target cells and cause a response.
2. There are 4 main types of signaling molecules:
a. Hormones are secreted from endocrine sources and some neurons and are then trans ported by the blood
to remote targets.
b. Neurotransmitters are secreted from neurons and act on immediately adjacent target cells for a short
c. Local Signaling Molecules are secreted from cells of many different tissues; they act locally and are
swiftly degraded.
d. Pheromones , which are secreted by exocrine glands, have targets outside the body; they integrate social
activities between animals.
3. Control and regulate body function and has a direct effect on homeostasis .
D. Hormone sources
1. Glands (Table 45.1, p. 940 & 941)
a. Pituitary gland & hypothalamus
b. Adrenal glands
c. Pancreas
d. Thyroid & parathyroid glands
e. Pineal gland
f. Thymus gland
g. Gonads (i.e. ovaries & testes)
2. Organs
a. Stomach
b. Small intestine
c. Liver
d. Kidneys
e. Heart
f. Placenta
II. Hormone Action (Fig. 45.1, p. 938)
A. The Nature of Hormonal Action
1. Different hormones activate different cellular response mechanisms.
2. Not all cells have receptors for all hormones.
3. Cells that respond are selected by means of the type of receptor they possess.
4. No receptor No response
B. Steroid Hormones (Fig. 45.5, p. 944)
1. Derived from cholesterol, are lipid-soluble and cross plasma membranes readily.
2. Steroids stimulate or inhibit protein (especially enzyme) synthesis by switching certain genes on or off.
a. They bind to chromo somal proteins in the nucleus and then activate transcription.
b. Testosterone is the male hormone with receptors throughout the body.
i. Hair follicles
ii. Larynx
iii. Muscle tissue
C. Peptide Hormones (Fig. 45.6, p. 945)
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