Download Lecture 15 - Intro to Endocrine - Linn

5/7/2010
Objectives
To define the endocrine system and associated
terminology.
To identify the different organs recognized as
being part of the End. System.
To identify the different ways that hormones may
be classified.
To describe the action of hormones.
To list the different hormones produced by the
pituitary gland and their respective actions.
Regulates
Metabolism
Growth
Water Regulation
Reproductive Cycles & Seasons
Response to Stress
Metamorphosis
Stimulates blood cell production
Lactation
Anatomy of the Endocrine System
Role of the Endocrine System
Communication & Regulation
Consists of the hormones and the various
cells and glands that secrete them, as well
as the target cells receiving the message.
Gland
An organ that synthesizes a specific
chemical substance.
Then secretes this substance either through a
duct or onto the surface of the body or directly
into the bloodstream.
Endocrine vs. Exocrine
Hormones
A chemical messenger liberated by a certain type of gland
and transported in the blood to a specific (target) organ.
“…..molecular triggers”
Types:
Based on composition (a.a., protein, lipid)
Based on speed (fast vs. slow acting).
Seconds days
Free vs. Bound
Effect on target cells
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Target Cell Specificity
Mechanisms of Hormone Action
Generalizations about receiving cells.
> Must have a specific protein receptor to accept
the Hormone.
> Binding Hormone with the receptor “turns on”
some genegene-determined function.
Cell activation depends upon:
1) Blood levels of the hormone.
2) Relative numbers of receptor sites.
3) Affinity (strength) of the bond
Hormone action on target cells
1.
2.
3.
4.
5.
Action of Hormones
Alter plasma membrane permeability of
membrane potential by opening or closing
ion channels
Stimulate synthesis of proteins or regulatory
molecules
Activate or deactivate enzyme systems
Induce secretory activity
Stimulate action e.g. mitosis
Steroid
hormone
Extracellular fluid
Slow acting – long lasting e.g. steroid
Cytoplasm
Fast acting – short duration e.g. peptide
hormones like thyroxine.
thyroxine.
Nucleus
Plasma
membrane
Receptor
protein
1 The steroid hormone
diffuses through the plasma
membrane and binds an
intracellular receptor.
Receptorhormone
complex
Figure 16.3, step 1
Steroid
hormone
Extracellular fluid
Cytoplasm
Receptor
protein
Nucleus
Plasma
membrane
Steroid
hormone
1 The steroid hormone
diffuses through the plasma
membrane and binds an
intracellular receptor.
Extracellular fluid
Plasma
membrane
Cytoplasm
Receptor
protein
Receptorhormone
complex
2 The receptorhormone complex enters
the nucleus.
Nucleus
Receptorhormone
complex
Hormone
response
elements
DNA
Figure 16.3, step 2
1 The steroid hormone
diffuses through the plasma
membrane and binds an
intracellular receptor.
2 The receptorhormone complex enters
the nucleus.
3 The receptor- hormone
complex binds a hormone
response element (a
specific DNA sequence).
Figure 16.3, step 3
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Steroid
hormone
Extracellular fluid
Receptor
protein
Cytoplasm
Receptor
protein
Receptorhormone
complex
2 The receptorhormone complex enters
the nucleus.
Hormone
response
elements
DNA
4 Binding initiates
transcription of the
gene to mRNA.
mRNA
1 The steroid hormone
diffuses through the plasma
membrane and binds an
intracellular receptor.
Receptorhormone
complex
Hormone
response
elements
Nucleus
3 The receptor- hormone
complex binds a hormone
response element (a
specific DNA sequence).
DNA
Plasma
membrane
Extracellular fluid
1 The steroid hormone
diffuses through the plasma
membrane and binds an
intracellular receptor.
Cytoplasm
Nucleus
Steroid
hormone
Plasma
membrane
mRNA
2 The receptorhormone complex enters
the nucleus.
3 The receptor- hormone
complex binds a hormone
response element (a
specific DNA sequence).
4 Binding initiates
transcription of the
gene to mRNA.
5 The mRNA directs
protein synthesis.
New protein
Figure 16.3, step 4
Figure 16.3, step 5
Other tissues and organs
Pituitary
Formerly known as “Master Gland”
a.k.a. Hypophysis
2 parts
Anterior Pituitary = adenohypophysis
…That produce hormones include:
- Adipose cells
- Thymus
- Cells in the walls of
the small intestine
& stomach
- Kidneys
- Heart
Glandular tissue
Posterior Pituitary = neurohypophysis
(H’s produced in hypothalamus)
Pituicytes (glialglial-like supporting cells) & nerve fibers
Pituitary-Hypothalamic
PituitaryRelationships
(c) Hormonal Stimulus
1 The hypothalamus secretes
hormones that…
Hypothalamus
Posterior lobe
2 …stimulate
the anterior
pituitary gland
to secrete
hormones
that…
Thyroid
gland
Adrenal
cortex
Pituitary
gland
Gonad
(Testis)
A down growth of hypothalamic neural tissue
Neural connection to the hypothalamus
Nuclei of the hypothalamus synthesize the
neurohormones oxytocin and antidiuretic
hormone (ADH)
Neurohormones are transported to the
posterior pituitary
3 …stimulate other endocrine
glands to secrete hormones
Figure 16.4c
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Hormones of the Pituitary
Anterior
-
(all are peptide H’s)
Growth hormone GH
Thyroid Stimulating TSH
Adrenocorticotropic ACTH
Follicle Stimulating FSH
Lutenizing LH
Prolactin
Posterior
(neurohormones)
- Antidiuretic ADH
- Oxytocin
- Melanocyte stimulating MSH
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