1. Endocrine System Chapter 16
Human Anatomy & Physiology 8/e, Marieb & Hoehn. (Pearson 2010)

2. Today’s class Endocrine glands and hormones
Mechanisms of hormone action
Hypothalamus and pituitary gland
Adrenal gland
Thyroid and parathyroid glands
Pancreas

3. Nervous and endocrine systems
Two systems of internal communication and regulation
act individually or together
Nervous system
high-speed electrical signals via neurons
Endocrine system
endocrine glands secrete hormones
slower, longer-acting responses

4. Endocrine glands Ductless Secrete hormones into bloodstream
hormones affect target with receptor
some prehormones and prohormones
fig 16.1

5. Types of chemical signals
pheromones
endocrine
paracrine
Human Reproductive Biology, 3/e. by S. Mader. McGraw Hill publishers fig 5A

6. Hormones trigger cell signalling
Three stages:
reception
signal transduction
response

7. Structural categories of hormones
Polypeptides and proteins
Amino acid derivatives (amines)
Steroids
(Eicosanoids)

8. Examples (autocrine regulator)
Struture determines if they find the receptor in/ out cell
(autocrine regulator)
(Anatomy and Physiology, 8/e, Seeley, Stephens and Tate, 2008, McGraw Hill, fig 17.3)

9. General hormone effects
Interactions
Synergistic (effect of 2 combine better than one)
Permissive
Antagonistic
Concentration
half-life (how long in the blood stream)
Target cell specificity
receptor type, number and affinity
upregulation, desensitization/downregulation
Affinity: how well the receptors will bind with the hormones.
-Can change the number of receptors

10. testosterone synthesized but no functional receptor
Importance of receptors e.g. complete androgen insensitivity syndrome (AIS)
XY individual
testes present
no ovaries or uterus
testosterone synthesized but no functional receptor
Human Reproductive Biology, 3/e. by S. Mader. McGraw Hill publishers fig 3.14

11. Mechanisms of hormone action
Peptide/protein/amines: receptors in Plasma membrane (cuz the molecules are too big)
different mechanisms, between from getting point A to B e.g.
cAMP – second message. 1st message in hormone
DAG/IP3 (phospholipase C) – cut the phosphol
tyrosine kinase
Activate “premade” proteins
Lipids: intracellular receptors
reach target via carrier proteins in plasma
why the need for carrier? Need a carrier cuz there hydrphobic and direct to the right tissue
nuclear hormone receptors as transcription factors
They create protein with transcription, translation, termination.

12. Recall cAMP as second messenger
Signal transduction
fig 16.2

13. Phospholipase C system
PIP IP3 + DAG
phospholipase C
Human Physiology, 10e, by Fox, McGraw Hill publishers, 2008, fig 11.9

14. Insulin and its tyrosine kinase receptor
Phosphorylates
no second messenger required
Human Physiology, 10e, by Fox, McGraw Hill publishers, 2008, fig 11.11

15. Lipid-soluble hormones
Last longer compare to premade protein
fig 16.3

16. Control of hormone release
Endocrine gland stimuli
Humoral
Neural
Hormonal
Nervous system modulation

17. Control of hormone release
Chemical control hormonal release
-Low calcium stimulates PTH (stimulates osteoclast)
fig 16.4

18. Hypothalamus and pituitary
Control much of endocrine system
Integrate nervous and endocrine systems
receives nerve signals from body
initiates appropriate responses
Neurosecretory cells
Posterior pituitary – not true (keeper and releaser of hyperthalmus)
stores and releases hormones made by hypothalamus
Anterior pituitary
Hypthalmus when to make/ nt make the hormones
true endocrine gland makes 6 trophic hormones

19. Hypothalamus and posterior pituitary
Oxytocin releasing milk
What are functions of oxytocin and ADH?
fig 16.5a

20. Hypothalamus and anterior pituitary
Dual capillary bed – rare
Anterior makes and release under the direction o the hypothalmus
fig 16.5b

21. Targets of anterior pituitary hormones
Prolactin – make the milk
Human Physiology, 10e, by Fox, McGraw Hill publishers, 2008, fig 11.15

22. Hypothalamus and anterior pituitary
Hypothalamic-releasing hormones stimulate anterior pituitary
gonadotropin-releasing hormone (GnRH)
prolactin-releasing hormone (PRH)
growth hormone-releasing hormone (GHRH)
corticotropin-releasing hormone (CRH)
thyrotropin-releasing hormone (TRH)

23. Hypothalamus-pituitary-target axis
Hypothalamus  anterior pituitary  target
GnRH  FSH, LH  gonads  sex hormones
PRH  prolactin  mammary glands
GHRH  growth hormone  various
CRH  ACTH  adrenal cortex  corticosteroids (stress response)
TRH  TSH  thyroid  metabolism hormones
Axis: Feedback loops – homeostasis

24. Feedback examples hypothalmus-pituitary-thyroid
hypothalmus-pituitary-gonad
axis
hypothalmus-pituitary-thyroid
axis
Human Physiology, 10e, by Fox, McGraw Hill publishers, 2008, figs 11.17, 11.18

25. Thyroid gland Located just inferior to larynx Follicles
follicular cells
thyroxine
colloid fluid
Parafollicular cells
calcitonin
metabolism
fig 16.8

26. Thyroid hormones T3 and T4 (thyroxine) Calcitonin
elevate basal metabolic rate
stimulate protein synthesis, increase respiration, etc
Calcitonin
lowers blood calcium concentrations
inhibits dissolution of calcium phosphate in bone
stimulates excretion of calcium in urine

27. Synthesis of thyroid hormone
Need iodine>> transport to cell> send both iodine thoridglobin >> to co
fig 16.9

28. Diseases of thyroid: hypothroidism
Hypothyroidism:  thyroid function
slower than normal metabolism
myxedama (fluid/mucoprotein accumulation in subcutaneous tissue)
Causes
Gland defect (e.g. by Hashimoto’s thyroiditis)
Too little TRH and/or TSH for trophic effects
Endemic goiter: by iodine deficiency
Hyperthyroidism:  thyroid function
more rapid than normal metabolism
e.g. by Grave’s disease (autoimmune)
autoantibodies are TSH receptor agonists
fig 16.10

29. Parathyroid glands 4 glands embedded in lateral lobes of thyroid gland
Secrete parathyroid hormone (PTH)
control of blood Ca2+ levels
fig 16.11

30. Recall
fig 16.12

31. Adrenal gland Outer cortex Medulla no neural innervation
steroid hormones
corticosteroids (corticoids)
aldosterone effects will be covered in more detail with urinary system
Medulla
preganglionic sympathetic neurons
catecholamines
epinephrine (mainly)
norepinephrine

32. Adrenal gland
Each zone make different hormones
fig 16.13

33. Cushing’s syndrome: excess glucocorticoid
Excess carocoid
fig 16.15

34. Stress and adrenal gland
Medulla make corticoamines
fig 16.16

35. Aldosterone release from adrenal cortex
* Aldosterone targets kidneys
fig 16.4

36. Pancreas Exocrine and endocrine Islets alpha cells: glucagon
in response to  blood glucose
stimulates liver: glycogen  glucose, fat hydrolysis
beta cells: insulin
in response to blood glucose
promotes entry of glucose into tissue
glucose  glycogen, fat
feeding versus fasting?

37. Pancreas and blood glucose homeostasis
Human Physiology, 10e, by Fox, McGraw Hill publishers, 2008, fig 11.31
fig 16.18

38. Other hormones Pineal gland: melatonin
Gonads (testes and ovaries): sex hormones
will be covered with reproductive system
Other organs (non-endocrine glands) secrete hormones
heart, GI tract, kidneys, skin, adipose tissue, skeleton, thymus

39. Up next December office hours Exam (cumulative)
Monday, December 6: 10-12, 2-4
Monday, December 13, 2-5
Exam (cumulative)
Tuesday, December 14, 9-11