1. The Endocrine System

2. introduction

3. Endocrine v Nervous Endocrine system
Releases hormones into interstitial fluid  blood  general circulation
Effectors: virtually any type of body cell; can have widespread effects on diverse aspects of metabolism
Slower, longer-lasting responses as hormones linger in blood

4. Hormone Action Hormones are carried in blood stream
Only certain cells can be affected by hormones
These target cells have 1000’s of receptors specific for a particular hormone.
Response determined by target cell: different cells may respond differently to the same hormone.

5. Location of Endocrine Glands

6. Hormone chemistry

7. Lipid-Soluble Hormones
Steroids, such as testosterone, estrogens
Thyroid hormones: T3 and T4
Nitric oxide (NO)

8. Lipid-Soluble Hormones1
Lipid-soluble
hormone
diffuses into cell
Blood capillary
Activated
receptor-hormone
complex alters
gene expression
Nucleus
Receptor
mRNA
Newly formed
mRNA directs
synthesis of
specific proteins
on ribosomes
DNA
Cytosol
Target cell
Transport
protein
Free hormone
Ribosome 2 3

9. Water Soluble Hormones
Amino acid derivatives, such as epinephrine, norepinephrine
Peptides: antidiuretic hormone (ADH), oxytocin
Proteins: insulin and growth hormone

10. Water Soluble Hormones
Receptor
cAMP serves as a
second messenger
to activate protein
kinases
G protein
Protein kinases
cAMP
Activated
protein
Protein—
Second messenger
Phosphodiesterase
inactivates cAMP
Activated adenylate
cyclase converts
ATP to cAMP
Activated protein
phosphorylate
cellular proteins
Millions of phosphorylated
proteins cause reactions that
produce physiological responses
Blood capillary
Binding of hormone (first messenger)
to its receptor activates G protein,
which activates adenylate cyclase
Adenylate cyclase
Target cell P
ADP
Protein
ATP 1 2 6 4 3 5

11. Control of Secretions Release occurs in short bursts Regulated by
Signals from nervous system
Example: epinephrine
Chemical changes in blood
Example: blood Ca2+ affects PTH
Other hormones
Example: ACTH from pituitary stimulates release of cortisol from adrenal cortex

12. Hypothalamus & pituitary

14. Anterior Pituitary Also called the adenohypophysis; it produces:
hGH (somatotropin)
IGF (Insulinlike Growth Factor)
TSH – Thyroid Stimulating Hormone
FSH – Follicle Stimulating Hormone

15. Anterior Pituitary LH – Luteinizing Hormone PRL – Prolactin
ACTH – Adrenocorticotropic Hormone
MSH – Melanocyte Stimulating Hormone
These are all regulated by release factors made in the hypothalamus

16. Posterior Pituitary
Also called the neurohypophysis; it stores and releases:
Oxytocin
ADH – Antidiuretic Hormone
These substances are produced by the hypothalamus

18. Glands of the body

19. The Thyroid Gland Produces thyroxin (T4) and triiodothyronine (T3)
Actions: Increases BMR (rate of O2 consumption) → body temp
Body growth and development
Also produces calcitonin
Lowers blood levels of Ca, P

21. The Parathyroid Glands
Produces Parathyroid Hormone (PTH)
Increases blood levels of Ca, P, Mg

22. The Pancreas
Pancreas is both endocrine and exocrine (digestive enzymes)
Islets of Langerhans produce glucagon and insulin
Glucagon increases blood levels of glucose
Insulin decreases blood glucose levels

24. The Adrenal Glands Adrenal Cortex
Mineralocorticoids such as Aldosterone – regulates Na+ (reabsorption) and K+ (excretion)
Glucocorticoids such as Cortisol – breaks down proteins and triglycerides; anti-inflammatory

25. The Adrenal Glands Adrenal Medulla
Produces epinephrine and norepinephrine
Stress response;
Fight-or-flight

27. The Pineal Gland Produces melatonin Biological clock
Levels increase in darkness and during sleep
Levels high in infants and young children; lower in adults