The Endocrine System

Chemicals control m[blank_start]etabolic[blank_end] processes, helping the body to maintain and sustain l[blank_start]ife[blank_end]. All cells have special receptor m[blank_start]olecules[blank_end] embedded into their membranes and their cytoplasm. Different types of cells have different types of r[blank_start]eceptors[blank_end] and will only respond to specific c[blank_start]hemical[blank_end] messengers in their environment. For a cell to respond to a stimulus signal t[blank_start]ransduction[blank_end] must occur. This is where a hormone will attach to the m[blank_start]embrane[blank_end] receptor on the outside of the cell and cause a set of reactions to occur inside the cell (the signal from the hormone is carried across into the cell).

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

[blank_start]Paracrine[blank_end] hormones bind to receptors on neighbouring cells. [blank_start]Endocrine[blank_end] 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. [blank_start]Autocrine[blank_end] hormones bind to receptors in the same cell that produced them.

- There are two main types of hormones: 1. [blank_start]Water[blank_end]-soluble hormones (proteins and amino acid derivatives): these can influence the passage of ions through the cell membrane and can repress or facilitate enzyme function. [blank_start]Fat[blank_end]-soluble hormones (steroids): these are able to pass through the cell membrane and can change gene expression - meaning they can cause or stop enzymes from being produced.

What is the order of the signal transduction pathway? A hormone must bind to a specific receptor. [blank_start]The receptor then rearranges its shape[blank_end] [blank_start]This change of shape then sends a messag[blank_end][blank_start]e through the cell membrane to other mo[blank_end][blank_start]lecules inside the cell (secondary[blank_end] [blank_start]messengers) to change their function.[blank_end] [blank_start]The change in their function then causes[blank_end] [blank_start]changes in the chemical pathways through[blank_end][blank_start]out the cell until these result in a[blank_end] [blank_start]final response to the hormone message.[blank_end] - 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 [blank_start]recycled[blank_end]. If these receptors are [blank_start]removed[blank_end], there are [blank_start]fewer[blank_end] receptors present which makes the cell less sensitive to that specific message. (Like tolerance). - When a cell [blank_start]reduces[blank_end] the amount of receptors present to a specific hormone, the process is called [blank_start]down-regulation[blank_end]. Insulin resistance is an example of this. - Conversely, if a cell receives [blank_start]weak[blank_end] signals, it can create more receptors to [blank_start]increase[blank_end] the cell's sensitivity to the message. The increase in the number of receptors is called [blank_start]up-regulation[blank_end]. An example of this is the sensitivity of the uterus to the oxytocin during pregnancy.

Where are hormones produced in mammals?

Where is the Pituitary Gland located?

What are the two lobes of the pituitary gland?

The pituitary gland is the master controlling gland of the endocrine system

The Neurohypophysis houses hormones produced by the...

The neurohypophysis is also known as the...

The neurohypophysis releases [blank_start]ADH[blank_end] and o[blank_start]xytocin[blank_end] which affect the kidneys and uterus respectively.

The Adenohypophysis is also known as the...

How many hormones does the Adenohypophysis produce?

What are some of the functions of the hormones produced by the Adenohypophysis?

The production of the hormones in the adenohypophysis is controlled by the...

The Pituitary is called the m[blank_start]aster gland[blank_end] The Hypothalamus is called the c[blank_start]ontrol centre[blank_end]

All endocrine glands are under the control of the pituitary or the hypothalamus

[blank_start]Adrenal Medulla[blank_end] - Fight, flight, freeze [blank_start]Hypothalamus via neurohypophysis[blank_end] - Stimulates release of milk and uterine contractions. - Stimulates reabsorption of water in kidney [blank_start]Adenohypophysis[blank_end] - Stimulates adrenal cortex. Progesterone and testosterone production. Maintains lactation after pregnancy. Stimulates thyroid gland. Promotes growth. Stimulates ovulation. [blank_start]Thyroid[blank_end] - Increase metabolic rate by stimulating cellular respiration; play an important role in growth, tissue development, and differentiation. [blank_start]Hypothalamus[blank_end] - Control release of hormones from anterior pituitary [blank_start]Parathyroid[blank_end] - Acts in opposition to calcitonin - removes calcium from bone, increases reabsorption of calcium in kidney, raises blood calcium levels. [blank_start]Adrenal Cortex[blank_end] - Regulate carbohydrate, salt, and water metabolism [blank_start]Testis[blank_end] - Initiates and maintains male secondary sexual characteristics [blank_start]Pancreas[blank_end] - Increases blood sugar levels by converting glycogen to glucose. - Decreases blood sugar levels by stimulating the formation of glycogen. [blank_start]Glands in stomach lining[blank_end] - Maintains flow of gastric juice [blank_start]Glands in duodenum lining[blank_end] - Stimulates secretion of intestinal juices and pancreatic juice, and stimulates release of bile from gall bladder. [blank_start]Ovary[blank_end] - Initiate and maintain female secondary sexual characteristics; maintains thickening of uterus lining; inhibits FSH and LH