37.3 Regulation of Body Processes

A G-protein is activated by a hormone binding to the receptor.

cAMP is broken down by an enzyme called phosphodiesterase.

CAMP is a very important second messenger.

The G-protein is inactive when a hormone is not bound to the receptor.

The G-protein is activated when a hormone is binding to the receptor.
GTP becomes inactive after hydrolysing into GDP.

The conversion of ATP to cAMP is done by adenylyl cyclase.

The structural orientation of a molecule is changed by the phosphorylation of it.
The activated molecule can change cellular processes.

As the signaling pathway progresses, the effect of a hormone is amplified.

The binding of a hormone at a singlereceptor causes many G-proteins to be activated.
The formation of many molecule of cAMP is triggered by each molecule of adenyl cyclylase.
Once activated by cAMP, there are many reactions.
The formation of a large amount of cellular product can be triggered by a small amount of hormone.
PDE is present in the cell and breaks down cAMP to prevent overproduction of cellular products.

The specific response of a cell to a lipid insoluble hormone depends on the type ofreceptors that are present on the cell membranes and the substrate molecule present in the cell cytoplasm.

Alteration of the hormone binding of a receptor can be accomplished by altering the pathways of metabolism and synthesis.

Many different body processes are affected by hormones.

The excretory system, reproductive system, metabolism, blood calcium concentrations, growth, and the stress response are some of the key regulatory processes that will be examined here.

It is important to maintain a proper water balance in the body.

When there is water loss caused by excessive perspiration, inadequate water intake, or low blood volume, the concentration of electrolytes in the blood rises.
There is a signal being sent from the osmoreceptors in the hypothalamic nucleus.
The anterior and posterior parts of the pituitary gland are present.
The anterior pituitary is made of glandular cells.
The hypothalamus is an extension of the pituitary.
The majority of it is composed of neurons that are in the hypothalamus.

The amount of water the kidneys excrete is regulated by ADH.

Salts and waste are concentrated in what will eventually be excreted as urine as a result of ADH.
The concentration of water in the blood is controlled by the hypothalamus.
Dehydration can cause an increase of osmolarity above 300 mOsm/L, which in turn raises ADH secretion and water will be retained, causing an increase in blood pressure.
The ADH changes the kidneys to become more permeable to water by putting water channels into the tubules.
The water moves out of the tubules through the aquaporins.
Blood osmolarity is lowered when the water is absorbed into the capillaries.
A negative feedback mechanism reduces osmoreceptor activity in the hypothalamus when blood osmolarity decreases.
Alcohol and other substances can cause increased urine production and dehydration.

Water can't be retained by the kidneys if the pituitary doesn't release enough ADH.

Increased thirst is caused by the fact that water is lost again and must be consumed.
Severe cases of dehydration can lead to electrolyte imbalances if the condition is not severe.

Aldosterone release can be stimulated by a decrease in blood pressure, or an increase in blood potassium levels.

It prevents sweat, saliva, and gastric juice from being Na+.
The reabsorption of Na+ results in the osmotic reabsorption of water, which affects blood volume and blood pressure.

The renin-angiotensin-aldosterone system is activated when blood pressure drops.

Renin circulates in the blood and reacts with the angiotensinogen in the body.
Angiotensin I is cleaved by renin and converted into angiotensin II in the lungs.

Increased Na+ reabsorption, water retention, and an increase in blood pressure can be caused by the release of the hormone aldosterone by the adrenal cortex.

Angiotensin II causes an increase in ADH and increased thirst, both of which help to raise blood pressure.

Angiotensin II stimulates the release of hormones.

Angiotensin II is formed when renin cleaves angiotensinogen.
The reproductive system is regulated by the action of hormones from the pituitary, adrenal cortex, and gonads.
In both males and females, FSH stimulates gamete production.
Gonad hormone levels increase when there is a negative feedback loop.

FSH stimulates the growth of sperm cells in males.

The hormone inhibin is released by the testes.

testosterone is the most common androgen in males.

Testosterone makes men produce sperm and masculine characteristics.
The role of testosterone production in the adrenal cortex is not fully understood.

The baseball player apologized and admitted to using steroids supplied by a trainer.

Athletes try to boost their performance by using artificial hormones.

One of the most popular performance enhancing drugs is anabolic steroids.

Steroids are used to build strength.

Erythropoietin, which stimulates the production of red blood cells, and human growth hormone, which can help in building muscle mass, are two hormones that are used to enhance athletic performance.
Performance enhancing drugs are not allowed for medical purposes.
The International Olympic Committee, the U.S. Olympic Committee, the Major League Baseball, and the National Football League all banned them.

Synthetic hormones can cause significant and nonreversible side effects.

There are a number of problems caused by androgens, such as infertility, and immune system depression.
The strain on the body caused by these substances is greater than what the body can handle, leading to unpredictable and dangerous effects and linking their use to heart attacks, strokes, and impaired cardiac function.

FSH stimulates the development of egg cells in females.

Follicle cells produce the hormone inhibin.
Estradiol and progesterone are hormones that help a woman get pregnant.
Secondary sex characteristics in females are produced by estradiol and progesterone.

Hormonal regulation of the female reproductive system involves hormones.

The production of milk is stimulated by prolactin.

The release of prolactin is stimulated by PRH.

The uterine smooth muscles are not very sensitive to oxytocin until after the baby is born.

O2 is released during childbirth when the uterus and cervix are stretched.
Contractions increase in intensity as blood levels of oxytocin rise through a positive feedback mechanism until the birth is complete.
The contraction of myoepithelial cells is stimulated by the drug.
As these cells contract, milk is forced from the secretory alveoli into milk ducts and is ejected from the breasts in milk ejection.

During periods of food consumption and periods of fast, the levels of blood sugar in the blood are different.

The hormones are responsible for maintaining blood sugar levels.

Additional regulation is caused by the hormones.

The cells of the body need food in order to function.

The body uses hormones to moderate the amount of energy it stores.

By increasing the rate of glucose absorption and utilization by target cells, lysin lowers blood sugar levels.

It stimulates the body to convert sugar to fuel, which is stored in cells for later use.
There are certain cells in the body that are more likely to be affected by Insulin, such as muscle cells and the liver.
This results from an increase in the number of glucose transporters in the cell.
As it binding to its target cell, it causes the cell to incorporate the transport of sugar into it.
The cell can be used as an energy source with this.
Some cells, including those in the brain and the kidneys, can use their own sugars.
The conversion of sugar to fat in adipocytes is stimulated by Insulin.
The hypoglycemic "low sugar" effect is caused by these actions that cause blood sugar concentrations to fall.

The animation shows the role of the pancreas in diabetes.

It can be caused by low levels of the cells in the pancreas that make the blood sugar-regulating drug, or it can be caused by reduced sensitivity to the drug.

High bloodglucose levels make it difficult for the kidneys to recover all the glucose from the urine.
The dehydration may be caused by the high amount of urine that is produced because of the less water being absorbed by the kidneys.
Nerve damage to the eyes and peripheral body tissues can be caused by high blood sugar levels.
If left unattended, this can cause unconsciousness or death, and can lead to muscle weakness.

The symptoms of diabetes are shown.

Glucose can be utilized as energy by muscle cells.

Glucagon stimulates the absorption of amino acids from the blood and converts them to sugars.

The actions of glucagon result in an increase in blood sugar levels.

There is a negative feedback mechanism that prevents the release of glucagon by the pancreas.

Excess glucagon may be produced by Pancreatic tumors.

The failure of the pancreas to produceinsulin leads to type I diabetes.

Blood sugar levels will not be affected by a pancreatic tumor and type I diabetes.

Hyperglycemia can be caused by a pancreatic tumor and type I diabetes.

Only the adult brain, uterus, testes, blood cells, and spleen are affected by these hormones.

They are transported across the cell's cell surface and bind to the cells' cells' cells' cells' cells' cells' cells' cells' cells' cells' cells' cells' cells' cells' cells' cells' cells' cells' cells' cells' cells' cells' In the nucleus, T3 and T4 are involved in energy production.
The hormone's calorigenic effect results in increased rates of metabolism and body heat production.

With the addition of iodine, thyroglobulin can be converted into hormones in the thyroid.

Iodine is formed from the ion that is transported from the bloodstream.

The tyrannosaurus rex has a peroxidase that attaches the iodine to the tyrannosaurus rex.

T3 and T4 have three and four iodine ion attached, respectively.
T3 and T4 are released into the bloodstream, with T4 being released in larger amounts than T3.
T3 is more active than T4 so tissues of the body convert T4 to T3 by removing an ion from it.
Most of the released T3 and T4 are attached to the bloodstream and unable to cross the cell's cell wall.
When blood levels of the hormone begin to decline, these molecule are released.
A week's worth of reserve hormone is kept in the blood.
Lower T3 and T4 release from the thyroid is caused by increased T3 and T4 levels in the blood.

In order to make T3 and T4 the follicular cells of the thyroid need anions of iodine.

A concentration that is 30 times higher than in blood is caused by the transport of iodides from the diet.

Due to the addition of iodide to table salt, the typical diet in North America provides more iodine than is required.

There is a fluid called colloid that contains thyroglobulin, and stimulation of the TSH results in higher levels of colloid in the thyroid.

In the absence of iodine, colloid is not converted to thyroid hormone and leads to goiter.

Disorders can be caused by underproduction and overproduction of hormones.

Hypothyroidism can cause growth defects in children.
Graves' disease is an example of a hyperthyroid condition.

The generation of muscle contractions and nerve impulses is dependent on the concentration of blood calcium.

If calcium levels get too high, the permeability of the membranes to sodium will decrease.
There can be convulsions or muscle spasms if calcium levels get too low.

PTH is released when there is low blood Ca2+ levels.

Ca2+ levels are increased by targeting the skeleton.
Ca2+ is released from bone into the blood when PTH stimulates osteoclasts.
Ca2+ deposition in bone is reduced by PTH.
PTH increases the absorption of Ca2+ in the gut and in the kidneys.
The effects of PTH on the intestine are not directly related to what it does on the kidneys.
The formation of calcitriol, an active form of vitamin D, is caused by PTH.
PTH release is stopped by rising blood calcium levels.

The parathyroid hormone is released in response to low calcium levels.

It increases blood calcium levels by targeting the bones.

This results in excessive calcium being removed from bones and introduced into blood circulation, which can lead to structural weakness of the bones, as well as nervous system impairment due to high blood calcium levels.

Hypoparathyroidism results in extremely low levels of blood calcium, which causes impaired muscle function and may result in tetany.

Calcitonin decreases blood calcium levels by stimulating osteoclasts, osteoblasts, and calcium excretion.

calcium is added to the bones to promote structural integrity.

When it stimulates bone growth, when it reduces maternal bone loss, and when it reduces bone mass loss, it's important in children.

In healthy adults, the role of calcitonin is unclear.

Most cells in the body are regulated by hormonal regulation.

There are two mechanisms of action for growth hormone.

The stimulation of triglyceride breakdown and release into the blood is the first direct action of GH.
Most tissues switch from using glucose as an energy source to using fatty acids.
In a direct way, GH stimulates the breakdown of glycogen in the body, which is then released into the blood.
The increase in blood sugar levels is due to tissues using more fat for energy needs.

It's important after a meal when the concentration of sugars in the blood are high.

The hormones produced by the hypothalamus regulate GH levels.

Growth hormone increases the rate of synthesis in bones.

The growth factor IGF-1 is activated by growth hormone and also allows formation of new proteins in muscle cells and bone.

Proper development depends on a balanced production of growth hormone.

Symmetrical body formation is the hallmark of pituitary dwarfism.
Some people are under 30 inches in height.
Individuals can reach heights of over eight feet in some cases.

When a threat is perceived, the body releases hormones that make it ready for a fight-or-flight response.

Increased heart rate, dry mouth, and hair standing up are all effects of this response.

The body's internal environment remains stable because of the interactions of the hormones.

Stressors disrupt homeostasis.
The fightor-flight response has evolved from the sympathetic division of the nervous system.
In the initial alarm phase, the sympathetic nervous system stimulates an increase in energy levels.
The body can respond to stress by either fighting for survival or fleeing from danger.

Glycogen reserves are exhausted after several hours and can't meet long-term energy needs.

Neural functioning could not be maintained if the only energy source available was glycogen reserves.
The body has evolved a response to counter long-term stress through the actions of the glucocorticoids, which ensure that long-term energy requirements can be met.
The conserved of salts and water is stimulated by the use of the glucocorticoids.
The human body has mechanisms to maintain its equilibrium.
The fight-or-flight response is present in all animals.

The stress response is regulated by the sympathetic nervous system.

The body responds to stress by releasing hormones that provide a burst of energy.

Epinephrine and norepinephrine increase blood sugar levels by stimulating the body's metabolism and by stimulating the release of blood sugar from the body's cells.
The hormones increase oxygen availability to cells by increasing the heart rate and dilating the bronchioles.

The hormones prioritize body function by increasing blood supply to essential organs such as the heart, brain, and skeletal muscles, while restricting blood flow to organs not in immediate need.

The catecholamines are Epinephrine and norepinephrine.

This Discovery Channel animation describes the flight-or-flight response.

The body can't sustain the bursts of energy.

Other hormones come into play.
The release of ACTH is triggered by the hypothalamus in a long-term stress response.
They affect cellular metabolism.
The hormones target the breakdown of fat in the body.
The fatty acids are released into the bloodstream for other purposes.

Glucocorticoids have anti inflammatory properties.

It can't be used long term as it increases susceptibility to disease due to its immune-suppressing effects.