Module 4 Flashcards
Hormones play a huge role in ________.
Digestive
What is the number one killer to hormones?
Stress
The nervous system is built for speed, it uses nerve impulses to prod the muscles and glands into immediate action so that rapid adjustments can be made in response to changes occurring both inside and outside the body. On the other hand what does the endocrine system do?
It moves slowly and uses chemical messengers called hormones, which are released into the blood to be transported leisurely throughout the body.
Although hormones have widespread and varied effects, the major processes controlled by hormones are:
Reproductions, growth and development, mobilizing body defences against stressors, maintain electrolyte, water and nutrient balance of blood, regulating metabolism and energy balance.
The endocrine system regulates processes that go on for _____ ____ _______ and, in some cases ___________.
Relatively long periods, continuously
What may hormones be defined as?
A chemical substance secreted by cells into the extracellular fluids, that regulate the metabolic activity of other cells in the body.
Although many different hormones are produced, nearly all of them can be classified chemicallas as either _____ ___-____ _____ (including _______, _______, and ______) or ________.
Amino Acid-Base Molecule (protiens, peptides and amines) steroids.
If we consider the local hormones called prostaglandins we must add a third chemical class why?
Because the prostaglandins are made from highly active lipids found in the cells of plasma membranes.
Where do steroids come from?
Made by the gonads and the hormones produced by the adrenal cortex.
What needs to be in order for a target cells to respond to a hormone?
Specific protein receptors must be present on its plasma membrane or in its interior, to which that hormone can attach.
Only when binding occurs, can the hormone influence the workings of a cell. True or False
True
What do hormones do to the body? Think Greek
They arouse or bring about their effects on the body’s cells primarily by altering cellular activity, by increasing or decreasing the rate of a stimulating a new one.
The precise changes that follow hormone binding depend on the specific hormone and the target cell type, buy typically one or more of the following occurs:
- Changes in the plasma membrane permeability or electrical state
- Synthesis of proteins or certain regulatory molecules (such as enzymes) in the cell.
- Activation or inactivation of enzymes
- Stimulation or mitosis
Despite the huge variety of hormones, there are really only two mechanisms by which hormones trigger changes in cells are?
Steroidal hormones and non-steroidal hormones
Steroidal hormones, being lipid-soluble molecules, the steroid hormones can do 6 things:
- Diffuse though the plasma membranes of their target cells.
- Once inside the steroid hormone enters the nucleus.
- Binds to a specific receptor protein there.
- The hormone receptor complex then binds to specific sites on the cell’s DNA
- Then activating certain genes to transcribe mRNA (messenger RNA).
- The mRNA is translated in the cytoplasm, resulting in the synthesis of new proteins.
Non-steroidal hormones, protein and peptide hormones, are unable to enter the target cells and instead bind to receptors situated on the target cell’s plasma membrane. How does this happen? 4 spets.
- The hormone binds to the membrane receptor
- Setting off a series of reactions that activates an enzyme.
- The enzyme, in turn, catalyzes a reaction that produces a second messenger molecule.
- That oversees additional intracellular changes that promote the typical response of the target cell to the hormone.
What prompts the endocrine system to release or not to release their hormones?
Negative Feedback Mechanisms.
What are negative feedback mechanisms?
The chief means of regulating blood levels of nearly all hormones.
In such systems, hormone secretion is triggered by some internal or external stimulus; then rising hormone levels inhibit further hormone release, even while doing what? And the result is?
Promoting responses in their target organs. As a result, blood levels of many hormones vary only within a very narrow range.
The stimuli that activate the endocrine system fall into three major categories, what are they?
Hormonal, Humoral and Neural
4 points of Hormonal
- is most common
- endocrine organs are prodded into action by other hormones
- hormones produced by the final target glands increase in the blood, they “feed back” inhibit the release of anterior pituitary hormones and thus their own release
- tend to be rhythmic, with hormone blood levels rising and falling again and again
2 points of Humoral
- changing blood levels of certain ions and nutrients stimulated humoral
- chemicals or elements in the blood that simulated the endocrine glands to function.
1 point of Neural
- this is isolated cases, nerve fibres stimulate hormone releases.
All though those three mechanisms (Hormonal, humoral and neural) typify most systems that control hormone release, they by no means explain all of them, and some endocrine organs respond to many different stimuli. True or False.
True