Neuroscience Part 3 Vocab

Endocrine glands

release hormones within the body

Hormones

chemicals that travel through the bloodstream to act on target tissues

Exocrine glands

use ducts to secrete fluid outside the body (e.g. tears and sweat)

Endocrine

hormone, released into the bloodstream, selectively affects distant target tissues

Synapse

chemical release and diffusionP

Pheromone

chemicals released outside the body to affect other individuals of the same species

Allomone

chemicals released outside the body to affect individuals of another species

Peptide hormone

a short string of amino acids

Amine hormones

modified version of a single amino acid, also called monoamine hormonesS

Steroid hormones

derived from cholesterol, made of four rings of carbon atoms

Neuroendocrine cells

neurons that release hormones into the blood — nuclei in the hypothalamus release two hormones, which affect social behaviors, into the media eminence in the posterior pituitary: Oxytocin and Arginine vasopressin (AVP)

Oxytocin

reproductive and parenting behavior, uterine contractions, and the milk letdown reflex (causes milk to be released from breasts)

Arginine vasopressin (AVP)

water conservation, increases blood pressure, pair-bonds

Pituitary gland

releases important hormones and regulates other endocrine glands

Pituitary stalk (dangly bit)

connects the pituitary to the hypothalamus

negative feedback

system output feeds back and inhibits further secretion

hypothalamus

regulates the release of tropic hormones from the anterior pituitary by secreting releasing hormones into the median eminence

tropic hormones

enter the general circulation and affect the secretion of endocrine organs throughout the body

endocrine cells (of the anterior pituitary gland)

synthesize and secrete many different tropic hormones

hypothalamus

controls gonadal hormone production by releasing gonadotrophin releasing-hormone(GnRH) into the median eminence

GnRH

stimulates the anterior pituitary to release one or both gonadotrophins: follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Testes

produce and secrete androgen (a steroid hormone)

Ovaries

produce progestins, such as progesterone, and estrogens, such as estradiol, steroid hormones (both)

Oral contraceptives

exerts negative feedback on the hypothalamus, inhibiting GnRH (e.g. birth control → basically stops whole cycle and does not release an egg for fertilization)

Sexual attraction

• brings males and females together

• may be synchronized with physiological readiness, odors

Appetitive behaviors

• Establish, maintain, or promote sexual interaction

• Proceptive female may approach males

• Males: stay near female, sniffing, singing, and nest-building

Copulation

• one or more intromissions — male penis inserted into female vagina

• Male ejaculation of sperm-bearing semen into the female:

• Refractory phase (male have so many females can override this period)

  • Coolidge effect

• If a female is willing to copulate, she is sexually receptive, or in estrus

Postcopulatory behavior

varies across species

• May include parental behaviors to nurture offspring

• copulatory lock occurs in dogs and some mice

lordosis

the receptive female adopts a posture allowing intromission → without this, no mating can happen

Activational effect

a temporary change in behavior due to the effect of a hormone

centromedial hypothalamus

crucial to the lordosis response

estrogen:

• Increase dendritic trees of neurons

• Stimulates progesterone receptors, which helps mediate lorosis

Periaqueductal gray

VMH sends axons here

located in the midbrain, which projects to other brain regions and to the spinal cord

medial preoptic area (mPOA)

coordinates male copulatory behavior by sending axons to the central midbrain and the spinal cord

Vomeronasal organ (VNO)

detects chemicals called pheromones

Pheromones

activate male arousal

Information from the VNO is sent to the medial amygdala, and then to the mPOA

Parabiotic

this preparation shows the effects of maternal hormones

sex determination

early developmental event that dictates whether a fetus will be male or female

sexual differentiation

the process by which individuals develop male or female bodies and behaviors

indifferent gonads

begin to differentiate in the first month

SRY gene

sex-determining region on the Y chromosome — responsible for the development of testes; without it, ovaries form (default development)

Testosterone

promotes the development of the wolffian system

Anti-muellerian hormone (AMH)

induces the regression of the meullerian system

5a-reducatse

enzyme; converts testosterone into the more powerful dihydrotesterone (DHT); required for male genitalia masculinization

Turner’s syndrome

a person has only one sex chromosome — a single X

• The individual develops as a female — no SRY gene = no masculinizing effects

Congenital adrenal hyperplasia (CAH)

causes developing females to be exposed to excess androgens before birth

• Newborns have normal ovaries; no testes; and may have intersex appearance

Androgen insensitivity syndrome (AIS)

occurs when an XY fetus has a defective gene for the androgen receptor

Sexual dimorphism

marked differences in appearance between males and females (also apparent in the brain)

Psychosocial dwarfism

the brain does not produce the releasing hormones that stimulate GH secretion, and growth is stunted

• results from neglect, abuse, stress in childhood

• Often, removal from situation restores growth

Homeostasis

the maintenance of a stable, balanced, internal environment

motivation

the psychological process that induces or sustains a certain behavior

Endotherms

generate their own heat through internal processes

Ectotherms

get most of their heat from the environment

Negative feedback

systems are the primary homeostatic mechanisms

set zone

refers to the range of tolerance in a system

Intracellular compartment

the fluid part of the body contained within cells

Extracellular compartment

the fluid in the space outside the cells, divided between interstitial fluid and blood plasma

Diffusion

molecules of a substance (solute) dissolved in another substance (solvent) will move until a uniform concentration is achieved

Osmosis

passive movement of solvent through a semipermeable membrane between solutions of different solute concentration until both sides become equal

Osmotic pressure

the force that pushes or pulls water across the membrane

hypovolemic thirst

low extracellular volume from a loss of bodily fluids stimulates this

osmotic thirst

high extracellular solute concentration, or very salty fluids, stimulates this

Baroreceptors

in blood vessels and the heart detect a drop in pressure

vasopressin

induces blood vessel constriction and slow production of urine

Osmosensory neurons

located in the hypothalamus specifically monitor changes in concentration of the extracellular fluid

Aldosterone

released in response to angiotensin II