chapter 24: hormones mood, emotion, growth, and more: hormones as master regulators lecture by...

Chapter 24: Hormones

Mood, emotion, growth, and more: hormones as master regulators

Lecture by Danielle DuCharme, Waubonsee Community College; clicker questions by Kristen Curran, University of Wisconsin-Whitewater

Hormones as Master Regulators

Hormones are chemical messengers that regulate cell functioning.

24.1 The “cuddle” chemical: oxytocin increases trust and enhances pair bonding.

Oxytocin influences, in humans, a propensity for trust.

This is demonstrated in the double-blind, investor-trustee experiment.

OxytocinThis hormone also plays roles in facilitating birth, making milk available to nursing babies, and increasing the propensity to form social attachments.

Consider the effects of oxytocin (emotions, birth faciliatation, making milk, etc.). What types of cell or cells does this hormone influence?

1. only neurons2. neurons and glia (supportive cells)3. neurons and cells of other female

reproductive organs4. cells of female reproductive organs

only5. only glia (supportive cells)

Take-home message 24.1

Complex emotions and behaviors can be influenced by chemical signals produced in the body.


Exposure to oxytocin, for example, causes humans to be more trusting of others, as well as facilitating birth, making milk available to nursing babies, and increasing the propensity to form social attachments.

24.2 Hormones are chemical messengers that travel through extracellular fluids to influence cells elsewhere in the body.

Animals have two systems for carrying out internal communication in response to external conditions.

Hormones

Hormones are a type of chemical messenger, secreted by cells into the extracellular fluid, including the bloodstream, and influencing the actions of cells elsewhere in the body as part of an internal communication and regulation system.

Endocrine and Target Cells

Cells that secrete hormones are called endocrine cells.

The cells that receive their signals are called target cells.

Endocrine Glands and System

Larger collections of hormone-secreting cells are called endocrine glands.

Together, all of the hormone-secreting cells in an animal make up its endocrine system.

Organizationof the Endocrine System

When a Hormone Reaches a Target Cell, It Elicits a

Response

Commonly, the hormone’s effect on a target cell is to alter the animal’s physiology in a way that helps the organism maintain homeostasis.

Another Type of Chemical Messenger

Pheromones are transported to the outside of an animal, and can cause a behavioral or physiological change in another individual.

Pheromone Categories

These chemical signals include:

Alarm pheromones Territorial pheromones Trail-marking pheromones Sex pheromones

Oxytocin is produced in the hypothalmus and secreted by the pituitary. It then binds to muscle cells in the breast to stimulate lactation. The hypothalmus is composed of ______, while the muscle cells act as ________.

1. hormones; target cells2. target cells; endocrine

cells3. endocrine cells; target

cells4. endocrine cells; hormones


Hormones are chemical messengers—secreted by endocrine cells and endocrine glands into the extracellular fluid—that influence the action of cells, called target cells, elsewhere in the body as part of an internal communication and regulation system.

24.3. Hormones can regulate target tissues in different ways.

The process by which hormones affect a particular cell is as follows:

1) signal is sent2) signal is received 3) cell responds

Hormones Come in Two Types

1) Peptide and protein hormones (water-soluble)

Example: Insulin

2) Steroid hormones (lipid-soluble)Example: Estrogen and testosterone

Differences in Hormone Types

The Chemical Structure of the Hormone Determines How It Regulates Activity in the Target Tissue

Peptide or protein hormones must align with a receptor to get through the phospholipid bilayer, altering it and causing action.

Steroid hormones pass directly through the cell membrane and meet a receptor in the cytoplasm or nucleus of target cells to take action.

Paracrine Regulators

These molecules generally diffuse from the tissue in which they are produced, through intracellular fluid, and into nearby tissue, binding to receptors in or on neighboring cells.

Both peptide and steroid hormones:

1. can diffuse across the cell membrane.

2. need to bind to their specific receptors.

3. only travel short distances through the body.

4. form a hormone-receptor complex that binds to DNA.

Take home message 24.3

Hormones can regulate the activities of a target tissue only if the cells have a receptor for the hormone.


Most hormones are one of two types: 1) peptide and protein hormones, which cannot

pass through cell membranes, and interact with receptors embedded in the membrane, or

2) steroid hormones, which can diffuse through cell membranes, then interact with their receptors in the cytoplasm or nucleus of the target cell.


Both types of hormones, once bound to a receptor, cause changes in the target cell, including influencing the rate of transcription of genes.

24.4 Where do hormones come from? 1. The hypothalamus controls the pituitary.

The hypothalamus, a structure on the underside of the brain, functions as a liaison between the nervous and endocrine systems.

The Pituitary Gland

Attached to the hypothalamus by a thin stalk is a gland about the size of a pea, called the pituitary gland.

Signals from the hypothalamus directly influence the pituitary gland.

The Hypothalamus and Pituitary Gland

The Pituitary Gland is Actually Two Glands Fused

TogetherThe posterior pituitary is developed from nervous tissue, and releases oxytocin and antidiuretic hormone (ADH).

The Pituitary Gland Is Actually Two Glands Fused

TogetherThe anterior pituitary is developed from epithelial cells, and produces numerous hormones.

Anterior Pituitary

The anterior pituitary gland produces:Thyroid-stimulating hormone (TSH) Follicle-stimulating hormone (FSH)ProlactinAdrenocorticotropic hormone (ACTH)Growth hormone

Improper Pituitary Function

Improper functioning of the pituitary can lead to some anomalies in growth and development.

Hormone Regulation

It is important to remember that the hypothalamus and pituitary don’t necessarily control all of the hormone secretions; they are, in turn, regulated by the glands that they regulated, through numerous feedback loops.

Which organ below acts as a liaison between the nervous system and endocrine system?

1. hypothalmus2. anterior

pituitary3. posterior

pituitary4. All of the above.

Classroom Catalyst

Gigantism

I would be happier if I was taller than I am now.

1. Strongly agree2. Agree3. Neutral4. Disagree5. Strongly

disagree

Some parents ask that their children be treated with growth hormone, even if they do not have the diseases we discussed. This is okay because this will make the children taller, and they’ll be able to enjoy some of the social advantages to being tall.


disagree


The hypothalamus functions as a liaison between the nervous and the endocrine system.


It receives input from the neurons throughout the brain and the rest of the body, and using this information about the internal and external environments, it sends out the appropriate hormones (and nervous signals), often directing the pituitary gland to release hormones with important regulatory control over body tissues.

24.5 Where do hormones come from? 2. Other endocrine glands also produce and secrete hormones.

The most important endocrine glands include:

Adrenal glands Pineal gland Thyroid gland Pancreas Gonads

Function of the Endocrine System Glands

Adrenal Glands

Regulating an organism’s response to stress is largely a function of the secretions of the two adrenal glands.

Adrenal Glands

They sit above the kidneys and secrete the hormones cortisol and adrenaline, among others, driving actions like the “fight-or-flight” response.

Pineal Gland

This gland has neuron connections with the retina of the eye and controls the secretions of the hormone melatonin, which is derived from the amino acid tryptophan and affects diurnal-nocturnal wake and sleep patterns, called circadian cycles.

Thyroid Gland

One of the largest endocrine glands in humans, the thyroid gland, is found in the neck, just below the Adam’s apple in men.

Thyroid Gland

It secretes hormones—including thyroxine—that influence the speed and efficiency at which body cells break down macromolecules in the diet and use the energy released from food to produce proteins.

Thyroid Gland

This gland controls most of what we think of as metabolism.

Goiter is a common health problem caused by the enlargement of the thyroid gland.

Thyroid Gland

The thyroid is also responsible for regulating levels of calcium in the blood.

It does this by regulating release of

calcitonin.

Thyroid Gland

Also, the embedded parathyroid glands play a central role in regulating calcium levels in adults.

Pancreas

Located next to the stomach and connected to the small intestine via a short duct, the pancreas is an endocrine gland that is most important in controlling the levels of blood glucose.

Pancreas

The pancreas maintains blood glucose within narrow ranges through the coordinated secretions of insulin and glucagon.

Gonads

The sex steroids, including testosterone, estrogen, and progesterone, are produced largely by the gonads—the testes in males, and the ovaries in females.

Gonads

The hormones produced here are responsible for numerous physical, behavioral, and emotional features, including much sexual behavior and growth, sexual development, and maintenance of gamete production.


Endocrine glands throughout the body are responsible for detecting and responding to signals reflecting an organism’s internal and external environments.


The adrenal glands regulate responses to stress.

The pineal gland regulates sleep and wake cycles.

The thyroid gland influences the speed and efficiency of cellular metabolism.


The pancreas maintains blood glucose within a narrow range.

The gonads produce hormones responsible for numerous physical, behavioral, and emotional features, including much of sexual behavior, development, and growth.

24.6 Hormones Can Affect Physique and Physical

Performance

Athletes seek out ways to increase the amount of certain hormones in their bodies.

One of these hormones is testosterone.

Effects of Testosteron

e

Use of performance-enhancing drugs in sports should be allowed.


disagree


Hormones affect a person’s physique and physical performance.

Testosterone, for example, increases muscle mass while reducing fat storage, and can increase speed and stamina.


It produces these changes by influencing gene expression and protein synthesis in cells with testosterone receptors.

24.7 Hormones can affect mood.

Many hormones have pronounced effects on moods, defined as relatively long-lasting emotional states.

These include: estrogen, testosterone, melatonin, and cortisol.

Estrogen

In women, the levels of estrogen in the bloodstream change throughout life.

And, the incidence of depression follows a similar pattern.

Testosterone

Testosterone can cause increased ratings of a variety of feelings.

This hormone can cause men to become energetic, euphoric, confident, and charismatic.

Testosterone

Studies of male athletes in a variety of competitive settings have documented that testosterone levels—and the mood changes they influence—rise in competitors prior to a competition.

Melatonin

Oral melatonin can induce hypnotic, sedative-like effects and improve sleep efficiency.

Melatonin supplementation can reduce vigor and increase fatigue and confusion.

Cortisol

Large amounts of cortisol can trigger depression and anxiety.

Cortisol

Rodents exposed to cortisol in drinking water exhibited anxiety-like behavior.

1. melatonin.2. estrogen.3. testosterone.4. cortisol.

While taking an exam you might experience increased levels of:


Many hormones, including estrogen, testosterone, melatonin, and cortisol, have pronounced effects on moods.

24.8 Hormones can affect behavior.

Animal behavior can be altered by the presence, absence, or change in the amount of a hormone.

This is seen in genetic manipulation of hormone levels and physiological supplementation of hormone levels.

Hormones and Human Behavior

Should sex offenders be castrated to modify their dangerous behavior?

This issue is hotly debated.

Using what you know about hormones, what do you think?

Which effect below is caused by increased levels of testosterone?

1. increase in muscle mass2. increase in aggressive behavior3. increase in obsessive-

compulsive behaviors4. All of the above.

Sex offenders should be castrated to modify their behavior.1. Strongly agree2. Agree3. Neutral4. Disagree5. Strongly

disagree

Take-home message 24.8 Many studies—including genetic

manipulations and physiological alterations of hormone levels—describe laboratory and field research demonstrating hormone influences on the development and expression of behaviors.

24.9 Hormones can affect cognitive performance.

Studies have been designed to evaluate whether or not cognitive abilities are influenced by hormones, with particular emphasis on the reproductive hormones estrogen and testosterone.

Effects of Hormones on Cognitive Tasks

Studies on the effects of hormones on cognitive performance have focused on two primary types of measures, designed to reflect different aspects of cognition:

Motor and verbal tasks Spatial tasks

Difference in Ability Due to Abundance or Lack of

Hormones

Boys vs. Girls On average, men

may have better spatial understanding . . .

but, women remain more likely to make the honor roll and perform well in school!

Hormones and Memory

Estrogen could boost the memory by increasing the growth of neurons and the connections between them.

Up to a point, cortisol improves memory—but too much of this and other stress hormones reduce performance on tests of memory.


A great number of experimental studies demonstrate that cognitive abilities in humans—primarily in motor and verbal tasks and spatial tasks—are influenced by hormones.


The most influencial hormones are the reproductive hormones—estrogen and testosterone—but also include the stress hormone cortisol.

24.10 Hormones can affect health and longevity.

Human beings, cats, laboratory mice, and fruit flies have been shown to have longer lives when sterilized/castrated.

This suggests that reducing levels of circulating reproductive hormones increases longevity.

Calorie Reduction and Longevity

Researchers found that the amounts of luteinizing hormone, estrogen, and progesterone in the bloodstream were significantly reduced among calorie-restricted females compared to the controls.

Hormones, Longevity, and Cancer

Increased exposure to estrogen is associated with increased cancer risk.

Women taking oral contraceptives, which reduce a woman’s exposure to estrogen, have decreased incidences of ovarian cancer.

Hormones and Longevity

There is similar evidence of increased cancer risk linked to circulating levels of progesterone and testosterone.

Estrogen and Heart Disease

Estrogen reduces circulating levels of cholesterol—so, even in replacement, if this increases the risk of one condition (reproductive cancers) it can decrease another (heart disease).

Estrogen replacement also lowers the rate of bone loss.

Hormones, Health, and Longevity

While there are several strong links between hormones, health, and longevity, the complex and myriad ways in which hormones can affect health make it difficult to make simple predictions about these effects.

A positive effect of high levels of estrogen is:

1. increased memory.2. increased understanding of

spatial relationships.3. increased lifespan.4. decreased risk of cancer.


Hormones affect health and longevity in complex ways.


Sterilization of animals, for example, reduces levels of circulating reproductive hormones and increases longevity, usually due to reduced cancer mortality.


But, in other cases, such as hormone replacement therapy in women, the relationship is reversed, with treatment reducing the annual risk of death by about 50% and increasing longevity.

24.11 Chemicals in the environment can mimic or block hormones, with disastrous results.

The chemical DDT was used to combat insects, but had effects on other organisms as it traveled up the food chain.

Effects of DDT

In birds of prey, the DDT disrupted the development and functioning of reproductive tract.

It also caused the thinning of eggshells in some birds.

DDT Is an Endocrine Disruptor

Endocrine disruptors are chemicals manufactured by humans that, when taken up by organisms, can mimic, block, or otherwise interfere with their hormones, leading to harmful effects.

Effects of Endocrine Disruptors

Other Examples of Endocrine Disruptors

There are several types of endocrine disrupters:Polychlorinated

biphenyls (PCB’s)PhthalatesBisphenol A

Endocrine Disruptors Affect Many Animal Groups

A variety of animal groups seem to be adversely affected by endocrine disruptors, including:

MammalsFishes Invertebrates

Effects on Humans?

Although these effects have been noted in other groups, it remains controversial whether these chemicals cause endocrine disruption and health problems in humans.

Bisphenol A has been shown to mimic estrogen. What effects on animals would you expect from exposure to this chemical?

1. increase of male sexual characteristics in females

2. increase of female sexual characteristics in males

3. increase in the body size of males and females

4. decrease in the body size of males and females


Endocrine disruptors are chemicals manufactured by humans that, when taken up by organisms, can mimic, block, or otherwise interfere with their hormones.


These chemicals can lead to a variety of adverse physiological effects, often related to their feminizing effects.


Although endocrine disruptions have been demonstrated in numerous animal species, it remains controversial whether these chemicals cause endocrine disruption and health problems in humans.

chapter 24: hormones mood, emotion, growth, and more: hormones as master regulators lecture by...

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