Download Hole`s Human Anatomy and Physiology

PowerPoint Presentation
to accompany
Hole’s Human Anatomy
and Physiology, 9/e
by
Shier, Butler, and Lewis
Chapter 13
Endocrine System
Endocrine Secretion
• A hormone is a biochemical a cell secretes
into interstitial fluid that travels in the blood
and acts on target cells
• This is endocrine secretion
• Exocrine secretion releases substances into
ducts or tube
• Hormones help regulate metabolic
processes
Hormone Chemistry
• Steroid or
steroidlike
compounds
– derived from
cholesterol
Figure 13.3a
Hormone Chemistry
• Amines, peptides,
proteins,
glycoproteins
Figure 13.3b
Figure 13.3c
Figure 13.3d
Hormone Chemistry
• Prostaglandins
– paracrine
substances
– derived from
arachidonic acid
• Hormones can
stimulate target
cells even if very
low concentrations
Figure 13.3e
Hormone Action
• Hormones reach all cells but bind only
those that have specific receptors.
• Hormone receptors are proteins or
glycoproteins with a hormone binding site.
• Hormones bind to the receptors.
• The more receptors, the greater the
response.
Steroid Hormones
•
•
•
•
Soluble in the lipids of the cell membrane.
Easily diffuse into target cells.
Combine with specific protein receptors.
Hormone-receptor complex binds to a
specific region of DNA and activates genes.
• The mRNA directs synthesis of a particular
protein.
• The protein brings about cellular changes.
Figure 13.4
Nonsteroid Hormones
• Amines, peptides, and proteins combine
with receptors on the target cell membrane.
• Hormones bind at receptor binding sites.
• The activity site of the receptor interacts
with other membrane proteins.
• Receptor binding can trigger a cascade of
biochemical activity (second messengers).
Figure 13.5
Second Messengers
• The hormone is the first messenger.
• Cyclic AMP is a second messenger.
• Hormone-receptor complex activates a G
protein which activates adenylate cyclase
which converts ATP to cAMP.
• cAMP activates proteins kinases that
transfer phosphate groups from ATP to
proteins and activate them.
Figure 13.6
Second Messenger Responses
• Cellular responses
–
–
–
–
–
–
altering membrane permeabilities
activating enzymes
promoting protein synthesis
stimulating/inhibiting metabolic pathways
promoting cellular movements
initiating secretion of biochemicals
• Phosphodiesterase deactivates cAMP
Second Messengers
• Hormones whose actions depend upon
cAMP include TSH, ACTH, FSH, LH,
ADH, PTH, epinephrine, norepinephrine,
calcitonin, and glucagon.
• Other second messengers include cGMP,
diacylglycerol, and inositol phosphate
which releases calcium ions which combine
with calmodulin.
Prostaglandins
• Local acting paracrine substances
• Synthesized and released quickly and
inactivated quickly
• Can activate or inactivate adenylate cyclase
• Can relax or contract smooth muscle
• Stimulate hormone secretion
• Influence sodium ion movement
• Affect inflammation
Control of Hormone Secretion
• The hypothalamus
controls the anterior
pituitary through
release of tropic
hormones
• Glands can respond
directly to changes in
the composition of
the internal
environment
Figure
13.7
• The nervous system
can stimulate glands
Figure 13.8
• Two portions
Pituitary Gland
– anterior lobe
(adenohypophysis)
• TSH, GH, ACTH, FSH, LH,
PRL
• hypothalamic releasing
hormones affect secretion
– posterior lobe
(neurohypophysis)
• does not produce hormones
• secretes hormones
synthesized in neurosecretory
cell bodies in the
hypothalamus
Pituitary Gland
• Hypophyseal
portal veins
carry substances
from the
hypothalamus to
the pituitary
Growth Hormone
• GH
• Stimulates increase in size and mitotic rate
of body cells, increases fat utilization
• Enhances amino acid movement through
membranes and promotes protein synthesis
• Promotes long bone growth
• Growth hormone releasing hormone
(GHRH) stimulates secretion
• Somatostatin (SS) inhibits secretion
Prolactin
•
•
•
•
PRL
Sustains milk production after birth
Decreases LH secretion in men
Secretion stimulated by prolactin-releasing
hormone from the hypothalamus
• Secretion inhibited by prolactin-inhibiting
hormone from the hypothalamus
Thyroid-stimulating Hormone
• TSH, Thyrotropin
• Controls secretion of hormones from the
thyroid gland
• Thyrotropin-releasing hormone (TRH) from
the hypothalamus stimulates secretion
• High levels lead to goiter
Adrenocorticotropic Hormone
• ACTH
• Controls secretion of hormones from the
adrenal cortex
• Corticotropin-releasing hormone (CRH)
from the hypothalamus stimulates secretion
• Stress can stimulate CRH secretion
Follicle-stimulating Hormone
• FSH, glycoprotein gonadotropin
• Development of ovarian follicles,
stimulates follicular cells to secrete estrogen
• In men, stimulation of sperm production
• Gonadotropin-releasing hormone (GnRH)
from the hypothalamus stimulates secretion
Luteinizing Hormone
• LH or ICSH in men, glycoprotein
gonadotropin
• Promotes secretion of sex hormones
• In women, promotes egg release
• Gonadotropin-releasing hormone from the
hypothalamus stimulates secretion
Antidiuretic Hormone
•
•
•
•
ADH
Causes kidneys to reduce water excretion
In high concentration, raises blood pressure
Hypothalamus produces and neurosecretory
cells in the posterior pituitary release ADH
in response to blood water concentrations
and blood volume
Oxytocin
• OT
• Contracts muscles in uterine wall and those
associated with milk-secreting glands
• Produced by the hypothalamus and secreted
by neurosecretory cells in the posterior
pituitary in response to uterine and vaginal
wall stretching and stimulation of breasts