Endocrine ENDOCRINE SYSTEM
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Endocrine
ENDOCRINE SYSTEM
Function
• Help regulate internal functions
• Use chemical messengers
• Recall: Endocrine vs. Exocrine glands
• Nervous System vs Endocrine System
Target Specificity
• Lock ‘n Key action
• Hormone-Receptor Complex
Hormone
Receptor
Glands
ENDOCRINE GLANDS & HORMONES
Hypothalamus
• Functions both as an Endocrine Gland and nervous tissue.
• Location
• Hormones
– Tropic Hormones
Pituitary Gland
• Two Parts: Anterior and Posterior
• Anterior Pituitary Gland (APG)
– Growth Hormone (GH)
– Prolactin
– Thyroid Stimulating Hormone (TSH)
– Adrenocorticotropic Hormone (ACTH)
– Follicle-Stimulating Hormone (FSH)
– Luteinizing Hormone (LH)
Pituitary Cont’d
• Posterior Pituitary (PPG)
– Oxytocin (OT)
– Antidiuretic Hormone (ADH)
• Hypothalamic control:
– APG: stimulated by hormones from hypothalamus
– PPG: modified axons
Fig. 17.4
Third ventricle of brain
Median eminence
Hypothalamo–hypophyseal tract
Stalk (infundibulum)
Neurohypophysis:
Posterior lobe
Pars tuberalis
Anterior lobe
Adenohypophysis:
(a)
Optic chiasm
Nuclei of hypothalamus:
Paraventricular nucleus
Supraoptic nucleus
Oxytocin
Antidiuretic hormone
(b)
Portal venules
Posterior lobe
Anterior lobe
Hypothalamic hormones
Anterior lobe hormones
Pineal gland
Cerebral aqueduct
Mammillary body
Anterior Posterior
Primary capillaries
Neuron
cell body
Axons to
primary
capillaries
Floor of
hypothalamus
Gonadotropin-releasing hormone
Thyrotropin-releasing hormone
Corticotropin-releasing hormone
Prolactin-inhibiting hormone
Growth hormone–releasing hormone
Somatostatin
Follicle-stimulating hormone
Luteinizing hormone
Thyroid-stimulating hormone (thyrotropin)
Adrenocorticotropic hormone
Prolactin
Growth hormone
Superior hypophyseal
artery
Secondary
capillaries
Hypophyseal
portal system:
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Thyroid
Follicles: Produce Hormones
• Hormones
▫ Thyroxine (T4)
▫ Triiodothryonine (T3)
▫ Both used iodine and have nonspecific target cells
▫ Calorigenic effect
• Colloid: Stores Hormones, jelly-like structure
• Parafollicular Cells: Cells found between follicles produce Calcitonin
▫ Calcitonin
Fig. 17.9
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Follicle
TracheaInferior thyroid vein
(b)
Isthmus
(a)
Superior thyroid
artery and veinThyroid
cartilage
Thyroid
gland
Follicular
cells
Colloid of
thyroglobulin
C (parafollicular)
cells
b: © Robert Calentine/Visuals Unlimited
Fig. 17.7
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
TRH
TSH
Target organs
Thyroid hormone
Stimulatory effect
Inhibitory effect
2
3
4
1
5
6
+
+
+
+
Negative feedback
inhibition
–
-
-
• Location
• Parathyroid Hormone (PTH)
Parathyroid Gland
Adrenal Glands
• Sits on top of each Kidney
• Receives a lot of Blood from Renal Artery
• 2 sections:
– Medulla: Inner layer
– Cortex: Outer layer, has sub-layers or zones.
Adrenal Cortex
• Aldosterone
– Produced in outer zone
– Regulates Electrolytes
• Cortisol
– Produced in middle zone
– Regulates metabolism and glucose
• Androgens
– Produced in inner zone
– Sex steroids
Adrenal medulla
• Produces and releases epinephrine and noreprinephrine.
• Functions:
– Gluconeogenesis
– Glycogenolysis
– Increased cardiac function
– Increased blood flow to muscles
– Increased pulmonary ventilation
Pancreas
• Exocrine and Endocrine Gland
• Acinar Cells produce pancreatic juices
• Islet cells produce hormones
– Beta Cells
• Produce insulin
• Lowers Blood Glucose levels and stores glucose in cells
– Alpha Cells
• Produce glucagon
• Increase Blood Glucose levels by releasing glucose into blood stream
– Antagonistic Effect
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