1. Endocrine and Reproductive systems
I decided to combine these two systems as they are very closely related. We will start with the Endocrine system.
Terms to look for in the material:
Hormone
Target cell
Endocrine gland
Exocrine gland
Prostaglandin

2. The Endocrine system or ‘hormones ‘r us’
When you want to contact friends or associates, you can either call them directly and have a one-on-one conversation.
You can also use Social Media to disseminate your message to a larger audience.
Your cells can do the same thing: either target other individual cells or send out a ‘broadcast’ to other groups of cells.

3. As we have already seen, your nervous system works very much little a telephone.
Information (impulses) is sent out through the system of neurons, and these messages are spread rapidly from one cell to the next.
But the Endocrine system is more like a radio, broadcasting chemical messages.
These chemical messengers are called hormones, and are released from one part of the body to travel through the blood stream to another part of the body.
Much like radio broadcasts, hormones can affect almost every cell in the body.

4. Hormones act by binding to specific receptors on cell membranes or within cells.
Cells that have receptors for a particular hormone are called target cells.
If a cell lacks those specific receptors, the hormone will have no effect on it.
In general, cells react slower to the effects of hormones, and these effects last longer than nerve impulses.
It may take several minutes, hours, or days for the full impact of the hormones to be felt.
Many endocrine functions depend on two opposing hormones to work properly.

5. An example of these two opposing hormones would be insulin and glucagon.
Insulin prompts the liver to convert blood glucose into glycogen and store it.
Glucagon, on the other hand, signals the liver to convert glycogen to glucose and release it into the blood stream.
The opposing actions of these two hormones maintain homeostasis by keeping blood sugar levels within a narrow range.

6. Glands
A gland is an organ that produces and release a substance, or secretion.
Exocrine glands release their secretions through ducts either out of the body or directly into the digestive system.
Examples of exocrine glands include those that release tears, sweat, and digestive enzymes.
Endocrine glands usually secrete hormones directly into the blood stream.

7. Examples of endocrine glands are adrenal glands or the Islets of Langerhans in the pancreas.
Although not usually considered as endocrine glands, other body structures like bones, fat tissue, and the heart also produce and release hormones.

8. Diagram of endocrine systems

9. Like we noted in an earlier slide, the endocrine system was, at one time, to be the organ system that produced hormones.
Weirdly enough, nearly all cells have been shown to produce small amounts of hormonelike substances called Prostaglandins.
Prostaglandins are modified fatty acids that are produced by a wide ranges of cells
They generally effect only the cells and tissues that are nearby, and are sometimes called local hormones.
One class of prostaglandins causes the sensation of pain during a headache. Aspirin helps to stop this pain by interfering with the synthesis of these prostaglandins. (Here’s another weird side note – prostaglandins are names after the prostate gland, in which they were first discovered)

10. How do hormones affect cells?
Hormones fall into two general groups:
The steriods
The non-steriods
Steroids are produced from the lipid cholesterol
Non-steroids include proteins, small peptides, and modified amino acids.
Each type of hormone acts on a target cell in a different way.

11. Steroids Because they are lipids, steroids can easily cross cell membranes. Once through the cell membrane, steroids can enter the nucleus and change the pattern of gene expression of the target cell. This ability to alter gene expression makes steroids very powerful and long acting. An example of a steroid with long term consequences is Testosterone (responsible for secondary sexual characteristics in males.) Testosterone is produced from progesterone!

12. Non-steroid hormones
This group of hormones generally can’t cross cell membranes so they bind to receptors on the outside of the cell membrane.
The binding to the receptor sites causes the release of secondary messengers within the cell.
These secondary messengers affect cell activities.

13. Glands of the endocrine system (kinda sounds like a sequel to Penguins of Madagascar, doesn’t it?)
We will now look at the bits and bobs of the endocrine system. We will start at the top of the body and work our way down.
The Pituitary gland – this is a structure that dangles from a slender stalk of tissue from the base of the brain.
It is divided into 2 parts: the anterior part and the posterior part.
Proper functioning of this gland is critical for proper development as it secretes HGH.
Too much HGH during childhood and gigantism is the result. Andre the Giant would be an example.

14. Too little HGH will result in pituitary dwarfism – Verne Troyer is an example.
The hypothalamus – this is attached to the posterior pituitary, and is the link between the CNS and the endocrine system.
The hypothalamus controls the secretions of the pituitary system.
The activities of the hypothalamus are controlled by the levels of hormones and other substances in the blood, and by sensory information collected by other parts of the CNS.

15. Anterior Pituitary Hormones released by the indirect action of the hypothalamus
Follicle-stimulating hormone (FSH)
Stimulates the production of mature eggs in the ovaries and mature sperm in the testes
Luteinizing hormone (LH)
Stimulates ovaries and testes; prepares the uterus for the implantation of fertilized eggs
Thyroid-stimulating hormone (TSH)
Stimulates the synthesis and release of thyroxine from the thyroid gland
Adreno-corticotropic hormone (ACTH)
Stimulates the release of some hormones from the adrenal glands
Human Growth hormone (HGH)
Stimulates protein synthesis and growth in cells
Prolactin
Stimulates milk production in nursing mothers
Melanocyte-stimulating hormone (MSH)
Stimulates melanocytes in the skin to increase the production of melanin

16. Adrenal Glands and the Pancreas
Adrenal glands are the pyramid shaped structures that sit atop the kidneys.
These glands release hormones – adrenaline and cortisol – that assist the body to prepare for and deal with stress.
The Pancreas is unique in that it is both an exocrine gland and an endocrine gland.
As an exocrine gland, the pancreas releases digestive hormones.
As an endocrine gland, the pancreas is home to the ‘Islets of Langerhans’ – this cluster of cells releases insulin(beta cells) and glucagon(alpha cells) into the blood stream.

17. Insulin is released to lower the rise in blood sugar levels after eating.
If the blood sugar levels drop too low, glucagon is released to break down glycogen (stored in the liver).
Both of these hormones are necessary for the maintenance of the body’s state of homeostasis.
Type I diabetes is an auto-immune disease resulting from the immune system destroying the beta cells. Insulin must be supplied by external means.
Type II diabetes is when the pancreas produces low or normal amounts of insulin but there is a problem with the insulin receptors on the target cells. High percentages of body fat can lead to this insulin resistance.

18. The thyroid and parathyroid glands
The thyroid gland is at the base of the neck but wraps around the upper part of the trachea.
This gland is instrumental in regulating the body’s metabolism through the actions of the hormone thyroxin.
Thyroxin acts to speed up the metabolic rate. NOTE: Iodine is required to synthesize thyroxin. A lack of iodine will result in goiters, and can cause cretinism.

19. The thyroid also secretes calcitonin – a hormone that reduces blood calcium levels so the calcium is more readily absorbed into the bones.
The 4 parathyroid glands – located on the back side of the thyroid – secrete parathyroid hormone(PTH). This hormone does the opposite of calcitonin and signals the increase of blood calcium levels. The increased calcium requirements come from the bones.
PTH also signals the reabsorption of calcium by the kidneys, and the uptake of calcium from the digestive system.
PTH is necessary to promote the proper functioning of nerves and muscles, and proper bone structure.

20. Reproductive glands (aka the gonads)
The gonads – the ovaries and testes – are the reproductive glands.
The gonads have 2 important functions:
the production of gametes (eggs in females and sperm in males).
The secretion of the sex hormones (testosterone for males and the class of sex hormones called estrogens for females).