1. Chapter 45 Hormones and the Endocrine System
A hormone called ecdysteroid regulates the timing of metamorphosis in this anise swallowtail butterfly.

2. You must know: Two ways hormones affect target organs.
The secretion, target, action, and regulation of at least 3 hormones.
An illustration of both positive and negative feedback in the regulation of homeostasis by hormones.

3. Types of Intercellular Signaling
Endocrine Signaling: utilizes a blood vessel
Paracrine Signaling: convey messages between cells
Autocrine Signaling: convey message within the same cell
Synaptic Signaling: synaptic cleft and neurotransmitters
Neuroendocrine Signaling: Epinephrine, functions in the vertebrate body as the so-called “fight or flight” hormone (produced by the adrenal medulla, an endocrine gland) and as a neurotransmitter, a local chemical signal that conveys messages in the nervous system.

4. Endocrine System = Hormone-secreting cells + Tissues
Endocrine glands: ductless, secrete hormones directly into body fluids
Hormones: chemical signals that cause a response in target cells (receptor proteins for specific hormones)
Affects 1 tissue, a few, or most tissues in body
Or affect other endocrine glands (tropic hormones)
Regulation by Positive & Negative Feedback
Hormone is a chemical signal that is secreted into the extracellular fluid, is carried by the circulatory system (in the blood) and communicates regulatory messages within the body.
Hormone is Greek for “to arouse activity”

5. Pheromones Hormones Local Regulators
Chemical signal from 1 individual to another individual
Chemical signal from endocrine gland through blood to target cell
Chemical signal from one cell to an adjacent cell
Eg. ant trail; sex pheromones
Eg. peptide, steroid hormones
Eg. cytokines, growth factors, nitric oxide (NO)

7. Types of Hormones Peptide Steroid Water-soluble
Bind to receptors on plasma membrane & triggers signal transduction pathway
Affects protein activity already present in cell
Rapid response
Short-lived
Eg. oxytocin, insulin, epinephrine
Lipid-soluble
Enters cell & binds to intracellular receptors
Causes change in gene expression (protein synthesis)
Slower response
Longer life
Eg. androgens (testosterone), estrogen, progesterone, cortisol

9. Epinephrine: one hormone  many effects
Liver cells break down glycogen and release glucose
Blood vessels to skeletal muscles dilate
Blood vessels to intestines constrict

10. Master Glands
Hypothalamus
Pituitary Gland

11. Master Glands Hypothalamus Pituitary Gland
Receives info from nerves and brain
Initiates endocrine signals
Hypothalamus
Posterior pituitary gland:
Oxytocin: contract uterine muscles, eject milk in nursing
Antidiuretic Hormone (ADH): promote H2O retention by kidneys
Pituitary Gland
In the Brain
Hypothalamus: influences the pituitary gland - Makes hormones that tell other glands what hormones to make
Pituitary Gland: is the liaison between the endocrine and nervous system
Posterior Pituitary Gland runs concurrent with the hypothalamus
PG : Oxytocin – also responsible for social recognition and anxiety
AG: Growth Hormone which stimulates Cell Division and Growth
Anterior pituitary gland:
Follicle-stimulating hormone (FSH): development of ovarian follicles (eggs); promote sperm production
Luteinizing hormone (LH): trigger ovulation; stimulate testosterone production in testes

12. Hypothalamus regulation of Posterior Pituitary gland

13. Hypothalamus regulation of Anterior Pituitary gland

14. Thyroid: T3/ T4 to speed up metabolism
Calcitonin > Lowers blood Calcium – too much excreted by kidneys and moves back into the bones
Parathyroid: PTH – Raises blood Calcium

15. Pancreas:
Insulin > Lowers Blood Sugar > Cells take in Sugar > Liver and Muscle cells convert glucose to glycogen for storage > adipose cells convert glucose to fat
Glucagon: Raises blood sugar > Breaks up glycogen and fat to release glucose
Adrenal Glands: On top of your kidneys
Medulla: Epinephrine “fight or flight”
Cortex: Glucocorticoids – Anti-inflammatory
ACTH – Adrenaline: Increases heart rate & cuts off blood supply to digestive system & holds blood in organs
Ovaries: Estrogen and Progesterone > Female secondary sex characteristics
Testes: Androgens > Male secondary sex characteristics

16. Negative feedback systems: Thyroid hormones Blood Ca2+ levels
Blood glucose levels
Positive feedback system:
Oxytocin (birthing process; release of milk/suckling)
Thyroid Hormones:
PTH – Raises Blood Calcium
Calcitonin – Lowers Blood Calcium
Oxytocin:
Auditory Stimulus > Comes to the Hypothalamus from the nervous system > Hypothalamus nudges the pituitary glans which releases hormones to stimulate milk production & secretion

17. BIOFLIX: HOMEOSTASIS – BLOOD SUGAR
BIOFLIX: HOMEOSTASIS – BLOOD SUGAR

18. Control of Blood Glucose
High blood glucose
Liver breaks down glycogen and releases glucose into blood
Insulin released from pancreas
Body cells take up glucose
Liver stores glucose as glycogen
Glucagon released from pancreas
Blood glucose drops

19. Diabetes Mellitus Type I diabetes (10%):deficiency of insulin
Insulin-dependent
Autoimmune disorder  beta cells of pancreas destroyed
Type II diabetes (90%): failure of target cells to respond to insulin
Non-insulin dependent
Insulin produced  cells don’t respond (defect in insulin receptor or response pathway)
Risk factors: obesity, lack of exercise
There are two main types but each is marked by high blood glucose levels.
In people with diabetes, elevated blood glucose exceeds the reabsorption capacity of the kidneys, causing them to excrete glucose. This explains the presence of sugar in urine.
As glucose is concentrated in the urine, more water is excreted along with it, resulting in persistent thirst.
Without sufficient glucose available to meet the needs of most body cells, fat becomes the main substrate for cellular respiration.
Type One: Childhood Diabetes: Destroys the person’s ability to produce insulin. Insulin injections were taken from animal pancreases. Now use of genetically engineered bacteria.
Type Two: A reduced responsiveness of target cells due to some change in the insulin receptors.
More than 90% of people with diabetes have type two.

20. Thyroid Gland Graves’ Disease: Autoimmune disorder
Hypothalamus
TRH
Anterior
pituitary
TSH
Thyroid T3 T4
Graves’ Disease:
Autoimmune disorder
Antibodies bind to TSH receptor
Hyperthyroidism
High temp, sweating, weight loss, high BP
Grave’s Disease is the most common form of hyperthyroidism: protruding eyes, caused by fluid accumulation behind the eyes.

21. Stress and the Adrenal Gland

22. Ch. 45 Questions to Consider
Compare peptide hormones to steroids.
Explain how insulin and glucagon work to regulate blood sugar levels.
Which glands and hormones respond when your body is under stress?