1. ENDOCRINE SYSTEM Karen Lancour Patty Palmietto
National Bio Rules National Event
Committee Chairman Supervisor – A&P

2. Endocrine System Major Endocrine Organs Hypothalamus Pituitary gland
Pineal gland
Thyroid gland
Parathyroid gland
Thymus
Adrenal gland
Pancreas
Ovaries
Testes

3. ENDOCRINE SYSTEM AND HOMEOSTASIS

4. Feedback Mechanisms Stimulus Response
change in homeostatic environment
signal sent to CNS
Response
signal sent from CNS
produce effect
body returns to homeostasis

5. GLAND TYPES Exocrine gland Ducts Lumen and surfaces Endocrine gland
Chemical messengers
Blood stream

6. Hormones specific chemical compound
produced by a specific tissue of the body
released in the body fluids
carried to a distant target tissue
affects a pre-existing mechanism
effective is small amounts.

7. Hormones Chemical messenger Secreted by endocrine gland
Specific to target
Activate cellular change
Of 4 different chemical types

8. Classes of Hormones:
peptides – short chains of amino acids (most hormones) pituitary, parathyroid, heart, stomach, liver & kidneys
amines - derived from tyrosine and secreted by thyroid and adrenal cortex
steroids - lipids derived from cholesterol secreted by the gonads, adrenal cortex, and placenta
eicosanoid - Produced from 20-carbon fatty acid, arachadonic acid, produced in all cells except RBCs -
Prostaglandins and leukotrienes

9. Peptide/Protein Hormones
Most common hormone
translated, packaged, & sent
Hydrophilic/Lipophobic
Bind surface receptors at target
Binding mediates signal transduction/2nd messenger system

10. Protein/Peptide Hormones
Hydrophilic
Large
Can't fit through membrane
Second messenger mechanism of action
Most hormones
Example: Insulin

11. peptide and amines
Protein hormones (1st messengers) - bind to receptor on target cell triggering 2nd messenger to affect cell’s activity
hormone (1st messenger) does not enter the cell but
binds to receptor on the plasma membrane receptors
hormone-receptor complex activates G protein
generates chemical signal (2nd messenger) – most common is cAMP and IP3
2nd messenger chemical signal activates other intracellular chemicals to produce response in target cell

12. Amine Synthesized from a single amino acid Melatonin from tryptophan
Thyroid hormone from tyrosine
Catecholamines (EPI, DA) from tyrosine

13. Eicosanoid Produced from 20-carbon fatty acid, arachadonic acid
Produced in all cells except RBCs
2nd messenger
Prostaglandins and leukotrienes
inflammation

14. Hormone + Receptor

15. Steroid Hormones Small Hydrophobic/Lipophilic
Travel in blood w/carrier
Cytoplasmic or nuclear receptors
change protein synthesis
Example: estradiol

16. Steroid Hormones
Steroid hormones - bind to receptors within target cell and influence cell activity by acting on specific genes
hormone diffuses freely into cell where cytoplasmic and/ or nuclear proteins serve as receptors
hormone binds to receptor (hormone-receptor complex)
complex bonds to steroid response element (sections of DNA receptive to the hormone-receptor complex
hormone-receptor complex acts as transcription factor to turn target genes “on” or “off”

17. Hormone + Receptor

18. The H-P-A Hypothalamic-Pituitary Axis
Most feedback loops run through this axis
HPA mediates growth, metabolism, stress response, reproduction.
is secondarily in charge of almost everything else.

19. Neurosecretory Cells Specialized neurons
Synthesize and secrete hormones
Extend from HYPOTHALAMUS to POSTERIOR PITUITARY

20. Neurosecretory cells in Hypothalamus
Nuclei synthesize and secrete hormones
Neuronal connection to POSTERIOR pituitary
Antidiuretic Hormone (ADH), Oxytocin

21. Hypothalamus (general)
Connection to pituitary
Neuronal to POSTERIOR PITUITARY
Endocrine to ANTERIOR PITUITARY
RH = Pituitary releasing hormones
RIH = Pituitary release inhibiting hormones

22. Hypothalamus
Secretes regulatory homones RH
RIH
"Directs" pituitary

23. (Release-Inhibiting Hormone)
STIMULUS
Hypothalamus
Releasing Hormone
(Release-Inhibiting Hormone)
Pituitary
Stimulating Hormone
Gland
Hormone
Target

24. Hypothalamic Hormomes
Release Inhibiting Hormones
Somatostatin
Prolactin release inhibiting hormone-PIH
Releasing Hormones
Thyrotropin releasing hormone-TRH
Growth hormone releasing hormone-GHRH

25. Posterior Pituitary Hormones
Manufactured in Hypothalamus,
released from Post. Pit.
Oxytocin
Target = smooth ms. Uterus and Breast (&brain)
Function = labor and delivery, milk ejection,(pair bonding)
ADH (Vasopressin AVP)
Target = kidneys
Function = water reabsorption

26. Pituitary gland MASTER GLAND Anterior and posterior portions
Posterior connected to hypothalamus by infundibulum
Anterior connected via blood stream

27. Anterior Pituitary Hormones
TARGET
FUNCTION
Thyroid (TSH) Stimulating
Thyroid gland
TH synthesis &
release
Growth (GH)
Many tissues
growth
Adrenocortico-
Tropin (ACTH)
Adrenal cortex
Cortisol release
(androgens)
Prolactin (Prl)
Breast
Milk production
Follicle (FSH)
Gonads
Egg/sperm prod.
Luteinizing (LH)
Sex hormones

28. Control of Endocrine Function
Positive
or Negative Feedback mechanisms
Self-regulating system

29. (Release-Inhibiting Hormone)
STIMULUS
Hypothalamus
Releasing Hormone
(Release-Inhibiting Hormone)
Pituitary
Stimulating Hormone
Gland
Hormone
Target

30. Positive Feedback Not common Classic example:
Action of OXYTOCIN on uterine muscle during birth.

31. Positive Feedback Baby pushes on cervix Nervous signal to Hypothalamus
Hypothal. manufactures OXY
OXY transported to POSTERIOR PITUITARY & released
OXY stimulates uterine contraction
Loop stops when baby leaves birth canal

32. Negative Feedback Most common control mechanism
Level of hormone in blood or body’s return to homeostasis shuts off loop at hypothalamus and pituitary

33. Negative Feedback: Thyroid

34. Basic Structure of Feedback Loop
Environmental Stimulus
Stimulates Control Center (Brain-hypothalamus)
Hypothalamic hormones stimulate Pituitary
Pituitary hormone stimulate Target area
Target area produces change
Change acts negatively or positively on the cycle.

35. Specific Endocrine Events
Thyroid Hormone
Growth Hormone
Adrenal Cortex Hormones
Sex Steroids

36. Endocrine Disorders
Hyposecretion disorders are caused by too little hormone – they can be treated by addition of the hormone
Hypersecretion disorders are caused by too much hormone – these are much harder to treat

37. Thyroid Hormone  T3 & T4 stim. Or environmental stim. Hypothalamus
TRH stim. Anterior Pituitary
TSH stim. Thyroid
 T3 & T4 shuts off TRH and TSH production

38. Thyroid Problems
What would happen if the thyroid could no longer produce T3 and T4?
No negative feedback to hypothalamus and anterior pituitary

39. Hypersecretion of TSH or TH

40. Hyposecretion of TH

41. Growth Hormone Stimulus = Tissue growth/ repair
Hypothalamus releases GHRH
Anterior Pituitary releases GH
 Protein synthesis, growth, etc.
GH and release of somatostatin shuts off GHRH and GH release

42. GH as Juvenile

43. Adrenal Gland Adrenal gland located atop kidney Outer part = cortex
Secretes Cortisol (stress), Androgens, Aldosterone (electrolytes)
Inner part = medulla
SNS control
Secretes EPI & NEPI (fight or flight)

44. Adrenal Insufficiency
Addison’s disease--hyposecretion of cortisol
JFK
Darkened skin (ACTH mimics MSH)
Weight loss, hypoglycemia
Find the anomaly in the feedback loop.
Inability to handle stress

45. Sex Steroids Stimulus = low circulating T or E Hypothalamus = GnRH
Anterior Pituitary = FSH & LH
Gonads produce T and E
High T and E shut off GnRH and FSH/LH

46. Too many steroids

47. Diseases of the Endocrine System
Diabetes – increased levels of glucose in blood
Hypoglycemia - low blood sugar
Graves Disease – overactive thyroid
Goiter – enlarged thyroid gland