Download Hypothalamus

Chapter 19
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ENDOCRINE SYSTEM
Compare the basic organization and function of the ES and
the NS
Describe the structural and functional organization of the
hypothalamus and the pituitary and explain their relationship
Discuss the locations and structures of the thyroid,
parathyroid, and adrenal glands as well as the thymus and
the endocrine part of the pancreas.
List the hormones (and their function) produced by these
glands.
Briefly review the results of abnormal hormone production
Endocrine System Overview
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Ductless glands produce
hormones
Gland may be entire organ or
interspersed bits of tissue
Chemical classification of
hormones
Target tissues are identified
by receptors
Hypothalamus
Control Center for
internal environment
Regulates nervous and endocrine systems via
3 mechanisms:
1.
2.
3.
ANS centers exert nervous control on adrenal
medulla
ADH and Oxytocin production
Regulatory hormone production (RH and IH)
controls pituitary gland directly and all other
endocrine glands indirectly
Fig 19-3
Pituitary Gland (= Hypophysis)
Structure:
Infundibulum - connection to hypothalamus
In the sella turcica
Two parts with an embryonic double origin
Posterior Pituitary = neurohypophysis Storage shed for
ADH and Oxytocin (produced in ?)
Anterior Pituitary = adenohypophysis production of 7
peptide hormones, see fig 19.5
Histology
Fig 19-4
Hypophyseal Portal System

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Portal systems:
two capillary networks
in serial arrangement
Advantage?
Named after their
destination: . . .
Portal veins: blood
vessels that link two
capillary networks
Fig 19-6
Thyroid Gland
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Anterior surface of trachea
just inferior of thyroid
cartilage (or Adam’s apple)
Two lobes connected by
isthmus
Microscopic thyroid follicles
produce thyroid hormone
C Cells - produce calcitonin
(Ca2+)
Fig 19-7
Thyroid Gland Function

Goiter

Thyroxin (T4) and
triiodothyronine (T3)
 speed up metabolic
rate
Calcitonin  lowers
blood Ca2+ levels
Exophthalmus

Thyroid pathologies:
Hyper- and
Hypothyroidism
Hyperthyroidism
Hypothyroidism
Slowing of mind
and body
Four Parathyroid Glands
4 tiny glands embedded in the back of the thyroid
(superior and inferior)
Parathyroid hormone
(PTH; sometimes
also called
parathormone)
Function: antagonist
to Calcitonin
Fig 19-9
Thymus Gland


Inside thoracic cavity
immediately
posterior to sternum
above the heart
Most active in
infancy and
childhood - Largest
just before puberty

Thymosin - enhances
lymphocyte
production and
competence.
(important for immune
system)
Adrenal or Suprarenal Gland
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Cortex: corticosteroid production
aldosterone, cortisol, sexhormone
Medulla: modified sympathetic ganglion
produces adrenaline and noradrenaline
(parallels sympathetic division of ANS)
Histology
Fig 19-10
Pancreas

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Part of endocrine and
digestive systems.
(99% exocrine)
Pancreatic islets or islets of Langerhans

 cells: glucagon ( blood sugar levels by
stimulating liver to convert glycogen to glucose)
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 cells: insulin ( blood sugar levels by causing the
cells to take up glucose for use by the mitochondria)
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 cells: somatostatin