- Hormones are chemical ❌ that are produced by an ❌ to regulate the activity of cells and organs. They are produced in very ❌ quantities and transported to ❌ in other parts of the body.
- Each hormone regulates and controls the ❌ of a specific target structure (cell, muscle, or gland).
- The action of hormones is ❌ but long lasting because they travel long distances but some hormones will still be in the ❌ after the effect has been activated.
- A stimulus causes the production and ❌ of hormones by their generation cell as a result of internal or external ❌ detected by the ❌ system.

❌ hormones bind to receptors on neighbouring cells.

❌ hormones travel long distances through the blood supply of animals to reach the target cells that have receptors that are complementary to the shape of the hormone.

❌ hormones bind to receptors in the same cell that produced them.

What is the order of the signal transduction pathway?
A hormone must bind to a specific receptor.

❌
❌❌❌ ❌

❌ ❌❌ ❌

- Responses as a result of the pathway include: activating or inactivating enzymes, exocytosis, switching on and off genes, and opening or closing protein channels.

- Membrane receptors (which receive hormones) can be removed or ❌. If these receptors are ❌, there are ❌ receptors present which makes the cell less sensitive to that specific message. (Like tolerance).
- When a cell ❌ the amount of receptors present to a specific hormone, the process is called ❌. Insulin resistance is an example of this.
- Conversely, if a cell receives ❌ signals, it can create more receptors to ❌ the cell's sensitivity to the message. The increase in the number of receptors is called ❌. An example of this is the sensitivity of the uterus to the oxytocin during pregnancy.

❌ - Fight, flight, freeze

❌ - Stimulates release of milk and uterine contractions.

- Stimulates reabsorption of water in kidney

❌ - Stimulates adrenal cortex. Progesterone and testosterone production. Maintains lactation after pregnancy. Stimulates thyroid gland. Promotes growth. Stimulates ovulation.

❌ - Increase metabolic rate by stimulating cellular respiration; play an important role in growth, tissue development, and differentiation.

❌ - Control release of hormones from anterior pituitary

❌ - Acts in opposition to calcitonin - removes calcium from bone, increases reabsorption of calcium in kidney, raises blood calcium levels.

❌ - Regulate carbohydrate, salt, and water metabolism

❌ - Initiates and maintains male secondary sexual characteristics

❌ - Increases blood sugar levels by converting glycogen to glucose.

- Decreases blood sugar levels by stimulating the formation of glycogen.

❌ - Maintains flow of gastric juice

❌ - Stimulates secretion of intestinal juices and pancreatic juice, and stimulates release of bile from gall bladder.

❌ - Initiate and maintain female secondary sexual characteristics; maintains thickening of uterus lining; inhibits FSH and LH