Chapter 8: Hormones

endocrinology

hormone (traditional definition)

chemical messengers secreted into the blood by specialized epithelial cells

• responsible for many functions that we think of as long-term, ongoing functions of the body.

• Processes that fall mostly under hormonal control include metabolism, regulation of the internal environment (temperature, water balance, ions), and reproduction, growth, and development.

• Hormones act on their target cells in one of three basic ways:

(1) by controlling the rates of enzymatic reactions,

(2) by controlling the transport of ions or molecules across cell membranes, or

(3) by controlling gene expression and the synthesis of proteins.

half-life

rate of hormone breakdown is indicated by a hormone’s half-life in the circulation, the amount of time required to reduce the concentration of hormone by one-half.

• one indicator of how long a hormone is active in the body

prohormone

As the inactive preprohormone moves through the endoplasmic reticulum, the signal sequence is removed, creating a smaller, still-inactive molecule called a prohormone

In the Golgi complex, the prohormone is packaged into secretory vesicles along with proteolytic, rupture enzymes that chop the prohormone into active hormone and other fragments. This process is called post-translational modification

trophic hormone

hypersecretion/hyposecretion

anterior pituitary gland & posterior pituitary gland

Describe several broad processes (e.g. growth, reproduction) regulated by hormones

Recognize that hormones exert their effects at very low concentrations; explain how this is possible

Identify or describe how hormone activity is typically terminated

Identify or provide the major structural (chemical class) categories of hormones

Recognize that steroid hormones are all derived from cholesterol

Apply your understanding of differences in signaling between lipophilic and lipophobic molecules (chapter 6) to the actions of different classes of hormones

Differentiate between the synthesis, storage, and major/typical mechanism of action of peptide/protein hormones and steroid hormone

Recognize, and explain why, effects of peptide hormone action typically occur more quickly than those of steroid hormones

Give examples of hormones that operate independently of the nervous system (simple endocrine reflexes)

Given the components of an endocrine reflex, including one that operates by antagonistic control, predict the effect of a change in any component on the other elements of the system

Differentiate between the roles of the anterior and posterior pituitary gland and their connections to the hypothalamus

Recognize or identify the role of the anterior pituitary as a source of trophic hormones that stimulate other endocrine organs

Describe how negative feedback loops work in a hypothalamic-pituitary-target organ system

Given the components of a hypothalamic-anterior pituitary-target organ system, real or invented, predict the effect of a change in any hormone or its receptors on any other hormone in the same system

Given the levels of the component hormones of a system compared to normal levels, form a hypothesis about the location and direction of the problem (e.g. see Fig 8.14)

Provide or identify the major function of each of the trophic hormones of the anterior pituitary gland