Chapter 5: Hormones and Behavior Flashcards
Do hormones have one effect on different systems, or a variety of effects?
Variety
How do hormones affect the body?
In myriad ways.
What system do hormones interact with the most?
The Nervous System
Hormones
Chemicals secreted by one cell group, that travel through the bloodstream to act on targets.
Endocrine Glands
Release Hormones within the body
Exocrine Glands
Use ducts to secrete fluids such as tears and sweat outside the body
What are the 6 forms of chemical communication?
- Synaptic
- Endocrine
- Autocrine
- Paracrine
- Pheromone
- Allomone
Synaptic Communication
Involves chemical release and diffusion across a synapse
Endocrine Communication
A hormone is release into the bloodstream to act on target tissues.
Autocrine Communication
A released chemical acts on the releasing cell
Paracrine Communication
The released chemical diffuses to nearby target cells
Pheromone Communication
Hormones can be used to communicate between individuals of the same species
- Pheromones are released into the environment
Allomone Communication
Allomones are chemicals released by one species to affect the behavior of another species
What was the first major experiment on the endocrine system?
Arnold Berthold in 1800s
What did Berthold’s experiment examine?
The role of testes in roosters
Castration
Removal of the gonads (testes), resulting in behavioral and physiological changes.
What was Bertholds major findings in his experiment?
Testes release a chemical into the bloodstream that affects male behavior and body structure.
How did Berthold come to his findings?
He removed the testes of a rooster while it was young, and replaced the testes in adulthood.
Did the replacement of the testes in the rooster allow it to develop normally?
No - The rooster did not restore back to normal size, functioning, or behavior.
What did the replacement of the testes in the rooster indicate?
Hormones released by the testes must organize the body in a developmental manner.
What are the 8 general principles of hormone actions?
- Hormones act in a gradual fashion.
- Hormones act by changing the probability/intensity of a behavior (do not switch on and off).
- The relationship between behavior and hormones is reciprocal (influence each other)
- A hormone may have multiple effects, and one behavior can be affected by several hormones.
- Hormones often have a pulsatile secretion pattern (it bursts).
- Some hormones are controlled by circadian clocks.
- Hormones can interact with other hormones and change their effects.
- Hormones can only affect cells with a receptor protein for their hormone.
Neurons influence _______.
Hormone systems
What can both neurotransmitters and hormone do?
Bind to receptors and activate second messengers, which bring about changed in cellular function.
Neurosecretory Cells
Neurons that release hormones into the blood
What are Neurosecretory Cells crucial for?
Brain control of the hormone systems
What can some peptides serve as?
Neurotransmitters (neuropeptides) and hormones
What is the 1st difference of neural and hormonal communication?
- Neural communication travels to precise destinations.
- Hormonal communication spreads throughout the body and is picked up by cells with the proper receptor.
What is the 2nd difference of neural and hormonal communication?
- Neural messages are rapid
- Hormonal messages are slower
What is the 3rd difference of neural and hormonal communication?
- Neural messages travel short distance over the synaptic cleft.
- Hormonal messages may travel over a meter
What is the 4th difference of neural and hormonal communication?
- Neural messages are usually digital (all or none)
- Hormonal messages are analog (graded in strength)
What is the 5th difference of neural and hormonal communication?
- Neural communications are sometimes under voluntary control.
- Hormone messages are involuntary
What are the 3 major classes of hormones based on their structure?
- Protein
- Amine
- Steroid
Protein Hormones
A string of amino acids
- called peptide hormones
Amine Hormone
Modified amino acids
- called monoamine hormones
Steroid Hormones
4 rings of carbon atoms
- based on a cholesterol backbone
How do hormones exert effects on cells and tissues in the body?
- Promoting proliferation, growth, and differentiation of cells.
- Modulating cell activity
What is the 1st way hormones produce their physiological effects?
Protein and amine hormones bind to specific receptors on the surface of a cell. Causes release of a second messenger in the cell.
What is the 2nd way hormones produce their physiological effects?
Steroid hormones pass through the cell membrane and bind to receptors inside the cell.
- Steroid receptor complex binds to DNA and acts as a transcription factor (control gene expression)
= genomic effects of the steroid hormones
Protein and amine hormones act ____.
Rapidly
What happens when protein and amine hormones bind to the extracellular part of a receptor?
The receptor changes shape and the intracellular part activates a second messenger.
Steroid hormones act ___.
Slowly
What happens when steroid receptor complexes form?
They alter protein production with long lasting effects.
What do some steroids act on?
More than one receptor (receptor isoforms) with functional differences.
Receptor Isoforms
More than one receptor
What is necessary for the cell to respond to the steroid receptor complexes?
Steroid receptor cofactors
What do different cells express?
Different cofactors
What does the expression of different cofactors lead to?
Different effects on the same steroid receptor complex depending on the cofactor present.
What steroid has a non genomic effect?
Estradiol
Non Genomic Effect
A rapid, brief effect involving neuronal membrane receptors
What is an example of a non genomic effect?
Testosterone has rapid effects on receptors located in axons and other sites distant from the nucleus.
Sometimes the brain…
- Breaks down its own steroids
- Transforms one steroid into another
How is the release of hormones controlled?
Feedback systems
Negative Feedback
Output feeds back and inhibits further secretion.
Autocrine Response
An endocrine gland releasing hormone and feeding it back onto itself
Target Cell Feedback
The hormone acts on its target cells and had a biological effect
Biological Effect
Detected by the endocrine gland and inhibits further release
What do more complex endocrine systems involve?
Brain (usually hypothalamus)
Hypothalamus
Can direct hormone release
- The brain detects the hormone’s effects and exerts negative feedback onto the hypothalamus
What is the anterior pituitary gland involved with?
- Tropic Hormones
- Releasing Hormones
Tropic Hormones
Pituitary hormones that affect other endocrine glands
Releasing Hormones
Used by the hypothalamus to control the pituitary release of tropic hormones.
What are the 2 parts of the pituitary gland (hypophysis)?
- Anterior Pituitary
- Posterior Pituitary
The two parts of the pituitary are thought of as _____ _____.
Separate structures
Pituitary Stalk (infundibulum)
Connects the pituitary to the hypothalamus
What does the stalk contain?
Blood vessels and many axons (only extend to the posterior pituitary)
What two hormones does the posterior pituitary secrete?
- Oxytocin
- Vasopressin or Arginine Vasopressin (AVP)
Oxytocin
Involved in reproductive and parenting behavior
- also in uterine contraction and milk letdown reflex
Milk Letdown Reflex
Sucking stimulates a reflex which produces the milk
AVP / Vasopressin
Increases blood pressure and inhibits urine formation
What do vasopressin and oxytocin serve as?
Neurotransmitters in the hypothalamus
Hypothalamic Neurons
Synthesize releasing hormones
Median Eminence
Where the axons from releasing hormones converge
- Above the pituitary stalk
What are releasing hormones secreted into?
Local blood vessels called the hypophyseal portal system
What is released when the releasing hormones are carried into the anterior pituitary?
Tropic hormones
What is the hypothalamus influenced by?
- Circulating messages (other hormones)
- Synaptic inputs from other brain areas
What 6 tropic hormones does the anterior pituitary release?
- Adrenocorticotropic (ACTH)
- Thyroid Stimulating (TSH)
- Follicle Stimulating (FSH)
- Luteinizing (LH)
- Prolactin
- Growth (GH)
Adrenocorticotropic Hormone (ACTH)
Controls adrenal cortex and its steroid hormone release
Thyroid Stimulating Hormone (TSH)
Increases thyroid hormone release
Gonadotropins
Influence the gonads (testes)
Follicle Stimulating Hormone (FSH)
Stimulates egg containing follicles or sperm production
Luteinizing Hormone (LH)
-Stimulates the follicles to form the corpora lutea
- Promotes testosterone release
What 2 tropic hormones are gonadotropins?
- Follicle Stimulating Hormone
- Luteinizing Hormone
Prolactin
Stimulates lactation in females and is involved in parental behavior
Growth Hormone (GH)
Influences growth mostly during sleep.
What other hormone also evokes Growth Hormone release?
Ghrelin (stomach hormone)
What can alterations in hormone systems produce?
Profound effects on the individual
What is an example of an alteration in the hormone system?
Stress
Psychosocial Dwarfism
A failure to grow caused by stress in early life
Somatomedins
Hormones that normally aid growth
What are somatomedins released by?
The liver in response to growth hormones
What can interfere with growth hormone release?
- Stress
- Sleep deprivation
= negative effects on normal growth
Who normally shows psychosocial dwarfism?
Children growing up in severely abusive/stressful households
What does psychosocial dwarfism illustrate?
Interactions between “environment” and basic body functioning
Adrenal Glands
Located at the top of each kidney and secrete hormones
Adrenal Gland in mammals
Outer 80%
Adrenal Medulla in mammals
Core 20%
What two amine hormones does the Adrenal Medulla release?
- Epinephrine (adrenaline)
- Norepinephrine (non-adrenaline)
What are epinephrine and norepinephrine controlled by?
The sympathetic NS
Adrenocorticoids
Steroid hormones secreted by the adrenal cortex
Glucocorticoids
A subgroup involved with glucose metabolism
Cortisol
A glucocorticoid stress hormone that increases blood glucose and breaks down protein
HPA Axis
The system from the hypothalamus -> anterior pituitary -> adrenal gland
Mineralcorticoids
Adrenal steroids that affect ion concentrations in tissues
What is an example of a mineralocorticoid?
Aldosterone
Aldosterone
Acts on the kidneys to retain sodium
Sex Steroids
Steroid hormones produced in the adrenal cortex
What is an example of a sex steroid?
Androstenedione
Androstenedione
Affects patterns of body hair in men and women
What do the thyroid gland produce?
Thyroid hormones
What is the thyroid stimulating hormone (TSH) secreted by?
The pituitary gland
What is the release of thyroid stimulating hormone (TSH) controlled by?
- Negative feedback from blood levels
- Thyrotropin releasing hormone (TRH) from the hypothalamus
Thyrotropin Releasing Hormone (TRH)
Located in the hypothalamus and controls TSH
Thyroid Hormones
General effects on growth and basic nervous system functioning
What do thyroid hormones contain?
Iodine - dependent on its supply
Goiter
A swelling of the thyroid gland resulting from iodine deficiency
What can early thyroid deficiency result in?
- Congenital Hypothyroidism
- Cognitive impairments
Gonads
Ovaries and testes
- produce sex steroids
Gonadotropin Releasing Hormone (GnRH)
Released by the hypothalamus to control gonadal hormone production.
What does GnRH stimluate?
The anterior pituitary
- releases Follicle Stimulating Hormone (FSH) or Luteinizing Hormone (LH)
Kisspeptin
A hypothalamic peptide that stimulates GnRH
- involved in the onset of puberty
Gonadotropin Inhibiting Hormone (GnIH)
Released by the hypothalamus to inhibit gonadotropic secretion
What do testes produce?
Testosterone
Androgens
Male hormones
What is an example of an andorgen?
Testosterone
What does Gonadotropin Releasing Hormone (GnRH) regulate?
Luteinizing Hormone -> regulates testosterone
Ovaries
Produce hormones in cycles, called progestins
What is an example of a progestin?
Progesterone
What are example of estrogens?
- 17B Estradiol
- Estradiol
What controls ovarian hormone release?
- Luteinizing Hormone (LH)
2.Follicle Stimulating Hormone (FSH)
- Those are both controlled by GnRH
Oral Contraceptives
Contain synthetic steroids that inhibit the release of GnRH
What occurs when there is a lack of GnRH?
- Prevents the release of FSH and LH
= No egg is released by the ovary
Pineal Gland
A single gland on top of the brainstem
What does the pineal gland secrete?
Melatonin (amine hormone)
- almost exclusively at night
Melatonin
Provides a signal that tracks day length and the seasons
How does oxytocin play a role in social behavior?
Oxytocin is released during nursing interaction and orgasm
- promotes pair bonds in prairie voles
How does vasopressin play a role in social behavior?
In male prairie voles, it facilitates the formation of pair-bonds with females.
Prairie Voles are _____.
Monogamous
Meadow Voles are ____.
Not monogamous
Monogamous
One sexual relationship to one parter at a given time.
What does endocrine pathology resemble?
Psychiatric Disorders
What is are 2 examples of endocrine pathology resembling a psychiatric disorder?
- One type of ADHD involves decreased sensitivity to thyroid hormone
- Cushing’s Disease results from long term excess of glucorticoids, with symptoms of fatigue and depression.
What are the 4 ways the hormonal and neural system communicate?
- Neural to neural
- Neural to endocrine
- Endocrine to endocrine
- Endocrine to neural
What does experience affect?
Hormone secretion, which affects behavior, which affects future experiences
