Download
1 / 17
170 likes | 253 Views
Learn about hormones, how they travel in the body, target vs. nontarget hormones, connection to other systems, action of steroid and protein hormones, and the two-messenger system. Discover how the endocrine system regulates cell activity with examples and the role of negative feedback in hormone production regulation.
E N D
1. What are hormones? • Hormones are chemicals that regulate cells in the body. They are usually produced in one place but affect cells in another area.
2. How do hormones travel? • Hormones are secreted into the blood and the circulatory system carries them to other body organs.
3. Nontarget vs target hormones? • Nontarget hormones affect many different types of cells. • Examples: growth hormone, insulin, epinephrine (adrenalin) • Target hormones have a target, a specific type of cell that they act upon. • Examples: parathyroid hormone, gastrin
4. NS vs Endocrine System • Nervous system allows the body to adjust very quickly to changes in the environment. • Endocrine system maintains control over a longer period of time.
5. Connection between systems? • The hypothalamus in the brain controls the pituitary gland with nerve impulses. • The pituitary gland stimulates other glands to produce hormones that affect the nerve activity of the hypothalamus.
6. Hormones affect all cells? • Hormones do not affect all cells. It depends on the type of receptors the cell has and the number of them. • Ex. A cell can have a receptor for hormone A, but not hormone B, A will affect that cell but B wouldn’t. • Ex. Liver and muscle cells have lots of receptors for insulin; bone cells have few receptors for insulin, insulin has a greater effect on liver and muscle than on bone.
7. Two types of hormones • Steroid hormones – made of cholesterol and soluble in fat. • Examples are sex hormones (estrogen, testosterone) and cortisol • Protein hormones – made of chains of amino acids and soluble in water. • Examples are insulin, growth hormone, epinephrine
8. Action of Steroid Hormones • Hormone diffuses through cell membrane (because they are soluble in fat) of target cell • Hormone combines with receptor molecule • They move into the nucleus and attach to DNA • DNA activates a gene to produce a specific protein to cause the desired hormonal effect.
9. Action of Protein Hormones • Hormone attaches to receptor on cell membrane of target cell (can’t pass through membrane because not fat soluble) • This causes cyclic AMP to be formed • Cyclic AMP activates enzymes in the cytoplasm which triggers ribosomes to create a specific protein to cause the desired hormonal effect
10. Two messenger system • The action of protein hormones is often referred to as a “two messenger system”. • The hormone that arrived at the cell is the first messenger. • The Cyclic AMP within the cell is the second messenger.
Negative Feedback Is a type of control system that regulates hormone production Works similar to a thermostat on your furnace When the desired change is detected, the original action is inhibited
