D5: Hormones and Metabolism
Mission 1: Hormones
Mission Objectives. You should be able to...
1. Compare and contrast peptide and steroid hormones.
2. Identify the 10 major glands and what they secrete.
Endocrine glands are structures that secrete hormones (chemical messages) directly into the blood. These messages are transported to specific target cells. Hormones can be steroid, proteins, glycoproteins, polypeptides amines or tyrosine derivatives.
The following is from Bioninja.
Mission Objectives. You should be able to...
1. Compare and contrast peptide and steroid hormones.
2. Identify the 10 major glands and what they secrete.
Endocrine glands are structures that secrete hormones (chemical messages) directly into the blood. These messages are transported to specific target cells. Hormones can be steroid, proteins, glycoproteins, polypeptides amines or tyrosine derivatives.
The following is from Bioninja.
Steroid hormones can cross directly through the plasma membrane and the nuclear membrane and bind to receptors. Estrogen is a hormone that can do this. The receptor-hormone complex then serves as a transcription factor, promoting or inhibiting the transcription of a certain gene.
Calciferol, a steroid hormone, crosses the intestinal cell membrane and binds to a receptor within the nucleus of the cell. The receptor-hormone complex effects expression of the calcium transport protein calbindin in the small intestine which then allows for the absorption of calcium from the intestine. Cortisol, a steroid hormone, bind to receptors in the cytoplasm and the receptor-hormone complex then passes through the nuclear membrane into the nucleus to effect transcription. The hormone may have different effects in different cells and it may even have an inhibitory effect. When cortisol binds to its receptor in the cytoplasm of a liver cell and enters the nucleus, it activates many of the genes needed for gluconeogenesis. At the same time, cortisol decreases the expression of the insulin receptor gene, preventing glucose from being stored in the cells and also raising blood glucose. In the pancreas, the cortisol-receptor complex inhibits transcription of insulin genes (Oxford, 2014).
Second messengers are small water-soluble molecules that can quickly spread throughout the cytoplasm and relay signals throughout the cells. Calcium ions and cyclic AMP are two of the most common second messengers. A large number of proteins are sensitive to the concentration of second messengers (Oxford 2014). Read about epinephrine on page 696 in your text.
Paul Andersen of Bozeman Science gives a rundown of the major glands and the hormones they secrete.
Second messengers are small water-soluble molecules that can quickly spread throughout the cytoplasm and relay signals throughout the cells. Calcium ions and cyclic AMP are two of the most common second messengers. A large number of proteins are sensitive to the concentration of second messengers (Oxford 2014). Read about epinephrine on page 696 in your text.
Paul Andersen of Bozeman Science gives a rundown of the major glands and the hormones they secrete.
Mission 2: The Cost to Be the Boss
Mission Objectives. You should be able to...
1. Explain the functions of the hypothalamus and the pituitary gland.
2. Describe the structure of the pituitary gland.
3. List the hormones produced by the pituitary gland.
4. Explain the role ADH has on blood solute concentration.
The Hypothalamus and Pituitary Gland. Both the nervous system and the endocrine system play a role in homeostasis and in the control of other processes including reproduction. The hypothalamus links the the nervous system and the endocrine system via the pituitary gland. The role of the hypothalamus is to secrete releasing factors which stimulate the secretion of the anterior pituitary gland's hormones. The releasing factors are carried from the hypothalamus to the anterior pituitary gland by a portal vein (Oxford 2014).
The following is from Bioninja.
Mission Objectives. You should be able to...
1. Explain the functions of the hypothalamus and the pituitary gland.
2. Describe the structure of the pituitary gland.
3. List the hormones produced by the pituitary gland.
4. Explain the role ADH has on blood solute concentration.
The Hypothalamus and Pituitary Gland. Both the nervous system and the endocrine system play a role in homeostasis and in the control of other processes including reproduction. The hypothalamus links the the nervous system and the endocrine system via the pituitary gland. The role of the hypothalamus is to secrete releasing factors which stimulate the secretion of the anterior pituitary gland's hormones. The releasing factors are carried from the hypothalamus to the anterior pituitary gland by a portal vein (Oxford 2014).
The following is from Bioninja.
Hormones secreted by the pituitary gland control growth, developmental changes, reproduction and homeostasis. The pituitary has two parts: the anterior lobe and the posterior lobe. These are actually quite different glands and have different modes of operation. Below is an image from Bioninja showing the two halves of the pituitary gland.
Negative feedback is involved in the control of secretion of many pituitary hormones. ADH is an example. Blood solute concentration is monitored by osmoreceptors in the hypothalamus. If these receptors detect that the solute concentration is too high, impulses are sent along the axons of neurosecretory cells, causing ADH secretion to increase. ADH acts on the kidney and causes blood solute concentration to decrease. If blood solute concentrations decrease too much, the osmoreceptors pick that up also. Fewer or no impulses are sent via the neurosecretory cells so ADH secretion reduces or stops, which allows blood solute concentration to rise (Oxford 2014).
