Unit 3 Behavioral Neuroscience

Hormones

chemicals secreted by cells in one part of the body that travel through the bloodstream to act on targets in other parts of the body

Endocrine glands

release hormones within the body

Exocrine glands

use ducts to secrete fluids such as tears and sweat outside the body

Endocrine

a hormone is released into the bloodstream to act on target tissues

Synaptic (neurocrine)

chemical release and diffusion across a synapse

Autocrine

released chemical acts on the releasing cell

Paracrine

the released chemical diffuses to nearby target cells

Pheromone

hormones used to communicate between individuals of the same species; released into the enviroment

Allomone communication

chemicals released by one species to affect the behavior of another species.

Neuroendocrine cells

neurons that release hormones into the blood

Neuropeptides

can act as neuromodulators and alter sensitivity to transmitters

Neuromodulators

can modify the reactivity of cells to specific transmitters—they act more slowly than neurotransmitters and have longer-lasting effects.

Peptide hormone

short string of amino acids

amine hormones

modified amino acid (monoamine hormone)

Steroid hormones

four rings of carbon atoms (derivatives of cholesterol)

Second messengers

Cyclic adenosine monophosphate (cyclic AMP or cAMP), Cyclic guanosine monophosphate (cyclic GMP or cGMP), and inositol triphosphate

transcription factor

The steroid-receptor complex binds to DNA and controls gene expression

Steroid receptor cofactors

may be necessary for the cell to respond to the steroid-receptor complexes

nongenomic effect

a rapid, brief effect involving neuronal membrane receptors that steroids such as estradiol have

Neurosteroids

steroids made in the brain, including testosterone and estrogens

aromatase

an enzyme that the brain produces that can convert testosterone into estrogens

Negative feedback

output feeds back and inhibits further secretion

Autocrine feedback loop

endocrine cells release a hormone whose presence feeds back on the endocrine cells to inhibit further secretion

Target cell feedback

hormone acts on its target cells; the biological effect is detected by the endocrine gland and further release is inhibited

tropic hormones

released by the anterior pituitary gland and affects other endocrine glands

releasing hormones

used by the hypothalamus to regulate the pituitary’s release of tropic hormones

pituitary gland

releases important hormones and has two main parts (anterior and posterior) which develop from different embryonic tissues and are separate in function

pituitary stalk

connects the pituitary to the hypothalamus; contains many axons that extend only to the posterior pituitary

Oxytocin

is involved in reproductive and parenting behavior, uterine contraction, and the milk letdown reflex

supraoptic & paraventricular nuclei

synthesize oxytocin and arginine vasopressin (AVP) and transport them along their axons to the axon terminals

Arginine vasopressin (AVP)

or vasopressin, or antidiuretic hormone (ADH), increases blood pressure and inhibits urine formation

median eminence

axons of neuroendocrine cells converge; just above the pituitary stalk

hypophyseal portal system

blood vessels that secrete releasing hormones form a _____ and are carried to the anterior pituitary, which then releases tropic hormones

Adrenocorticotropic hormone (ACTH)

controls production and release of adrenal cortex steroid hormones (six main tropic hormones)

Thyroid-stimulating hormone (TSH)

increases thyroid hormone release (six main tropic hormones)

Follicle-stimulating hormone (FSH)

stimulates egg-containing follicles in ovaries or sperm production in males (six main tropic hormones)

Luteinizing hormone (LH)

stimulates follicles to form the corpora lutea in ovaries and testosterone production by the testes (six main tropic hormones)

rolactin

stimulates lactation in females and is involved in parental behavior (six main tropic hormones)

Growth hormone (GH)

somatotropin) influences growth, mostly during sleep. The stomach hormone ghrelin also evokes GH release (six main tropic hormones)

Adrenal glands

located on the top of each kidney, releases the amine hormones epinephrine (adrenaline) and norepinephrine (noradrenaline) which are controlled by the sympathetic nervous system

adrenocorticoids

steroid hormones secreted by the adrenal cortex

Glucocorticoids

subgroup involved with glucose metabolism

Cortisol

is a glucocorticoid stress hormone that increases blood glucose and breaks down protein

Mineralocorticoids

subgroup that affect ion concentrations in tissues

Aldosterone

acts on the kidneys to retain sodium

androstenedione

sex steroids that contribute to the adult pattern of body hair in men and women

thyroid hormones

thyroid stimulating hormone (TSH) causes the thyroid gland to produce _____ (thyroxine

(tetraiodothyronine) and triiodothyronine)

thyrotropin-releasing hormone (TRH)

stimulates the pituitary to secrete TSH and is released from the hypothalamus by negative feedback from blood levels

Goiter

a swelling of the thyroid gland resulting from iodine deficiency

congenital hypothyroidism

Early thyroid deficiency can result in cretinism, _________, accompanied by intellectual disability.

Pineal gland

secretes an amine hormone, melatonin, almost exclusively at night

Gonads

The ovaries and testes produce sex steroids

gonadotropin releasing-hormone (GnRH)

releasing these hormones controls gonadal hormone production in the hypothalamus

kisspeptin

GnRH neurons are stimulated by a hypothalamic peptide; involved in the onset of puberty

gonadotropin-inhibiting hormone (GnIH)

used by the hypothalamus to inhibit gonadotropic secretion

testes

produce and secrete testosterone, one of the many male hormones called androgens; regulated by LH which is regulated by gonadotropin releasing-hormone (GnRH)

Ovaries

produce hormones in cycles: progestins, such as progesterone, and estrogens such as 17β-estradiol; controlled by LH and FSH, which are controlled by GnRH

Oral contraceptives

contain synthetic steroids that feed back on the hypothalamus and inhibit release of GnRH; Lack of GnRH prevents release of FSH and LH, so no egg is released by the ovary

Psychosocial dwarfism

growth failure due to stress and neglect in early childhood; mediated through the CNS and its control over endocrine functions

Homeostasis

maintenance of a relatively stable, balanced internal environment

Motivation

psychological process that induces or sustains a particular behavior

Thermoregulation

regulation of body temperature around a set value

Ectotherms

get most of their heat from the environment; regulate body temperature by behavior

Endotherms

produce their own heat by metabolic processes. Enhanced capacity for oxygen utilization sustains greater muscular activity.

Allostasis

many physiological systems shift responses, depending on the nature of the stressors and prior experience, e.g., heart rate and blood pressure are continually shifted to accommodate current or anticipated activity levels

Redundancy

the body has multiple systems for regulating the internal environment; allows for compensation if one monitoring system fails

Intracellular compartment

fluid part of the body contained within the cells

Extracellular compartment

fluid outside the cells

Interstitial fluid

between the cells

Blood plasma

protein-rich fluid that carries red and white blood cells

aquaporins

specialized protein channels where Water moves in and out of cells

Diffusion

passive spread of molecules of one substance among molecules of another substance until uniform concentration is achieved

Osmosis

movement of water molecules through a semipermeable membrane, to equalize the concentration of two solutions

Osmolality

concentration of solute in a solution

isotonic

a salt solution is about 0.9%, (physiological saline); the same as in mammalian fluids.

hypertonic

a solution that has more salt

hypotonic

a solution that has less salt

Osmotic thirst

stimulated by high extracellular solute concentration. Water is pulled out of the cells when extracellular salt concentration is too high.

Hypovolemic thirst

stimulated by low extracellular fluid volume

Osmosensory neurons

in the hypothalamus and are neurons that specifically monitor the concentration of the extracellular fluid

Circumventricular organs

have fenestrated capillaries—lack the usual blood-brain barrier, allowing neurons in these regions to monitor salt concentration and hormones in the bloodstream

Aldosterone

a steroid hormone, is released from the adrenal gland in response to thirst signals

Baroreceptors

in major blood vessels and the heart detect the initial drop; the heart decreases

secretion of atrial natriuretic peptide (ANP)

vasopressin (antidiuretic hormone)

release caused by hypovolemia from the posterior pituitary gland, which induces blood vessel constriction and reduces water flow to the bladder

angiotensin II

To conserve water, the kidneys release an enzyme called renin, which triggers a hormonal cascade resulting in circulation of

Glucose

the principal sugar used for energy, especially in the brain

Glycogen

complex carbohydrate made of glucose molecules; stored for a short term in the liver and muscles

Glycogenesis

converting glucose to glycogen) is regulated by the pancreatic hormone insulin

Glycogenolysis

(converting glycogen to glucose) is controlled by glucagon

Lipids

(fats) for longer-term storage, are deposited in fat storing cells that form adipose tissue.

gluconeogenesis

If food deprivation is prolonged, ______ converts fat and proteins to glucose and ketones, a form of fuel

Basal metabolism

processes of heat production, maintenance of membrane potentials, and all other basic life- sustaining processes

trophic factors

substances that promote cell growth and survival

Glucodetectors

in blood and liver detect glucose and signal the pancreas to release insulin

vagus nerve

information from glucodetectors in the livers travels via

nucleus of the solitary tract (NST)

Information from glucodetectors in the liver travels via the vagus nerve to the brainstem

Diabetes mellitus

is caused by lack of insulin

Ventromedial hypothalamus (VMH)

lesions in this area resulted in animals overeating (is a satiety center)

hyperphagia

overeating

lateral hypothalamus

lesions in this area lead to a cessation of eating (is a hunger center)