Animal Behavior Unit 2

neuron

a specialized cell that allows animals to detect environmental stimuli and produce a motor or behavioral response to that stimuli; a unilateral communication portal

nerve net

a system of few, sparsely-distributed neurons

nervous system

a system of many, densely-distributed neurons

glia cells

nervous system cell that is smaller and more numerous than neurons; support neuron function and metabolic clean up

interneurons

nervous system cell that assists with neuron function

dendrites

branches off a neuron cell body that receives information from either the environment or another neuron

cell body

the metabolic center of the cell

axon

a neuron’s long branch emanating from the cell body that send information to other neurons or motor neurons in the form of an electrical signal

action potential

an electrical signal that neurons use to send information

axon terminal

communication junction of a neuron where a chemical messenger/neurotransmitter is released

biological clock

mechanisms that produce rhythms/cyclic activity that occurs on a predictable basis (hourly, daily, monthly, yearly, etc); present for all processes in the animal’s body

circadian rhythm

daily biological clock

endogenous

the controlling factor of a behavior is internal to the organism

actogram

record of activity

free running

the drift that occurs in rhythmic behavior when placed under constant conditions; creates a phase delay or advance

phase delay

periods greater than 24 hours occurring in circadian rhythms

phase advance

period lesser than 24 hours occurring in circadian rhythms

free running/endogenous rhythms

an animal’s inherent circadian period which does not align with the exact 24 hour day cycle (e.g. 23.9 hours, 24.1 hours, etc); occurs under free run

zeitgeber

time-giver, or any cue an animal can use to synchronize it’s biological clock; light is a common one, but not the only one

Suprachiasmatic Nucleus (SCN)

the major pacemaker in mammals; collection of specialized cells in the hypothalamus

chiasma

the point where the two optic nerves cross

hormones

organic molecules that are secreted by ductless glands (enters bodily fluid to reach target tissues); typically act in minute quantities

peptide and protein hormones

a string of amino acids (short for peptides, longer for proteins)

steroid hormones

more evolutionarily conserved; majority derived from cholesterol

sex steroid hormones

includes androgens, estrogens, and progestins

adrenal steroid hormones

hormones from the adrenal gland that affect stress responses, metabolism, and blood pressure regulation

preprohormone

the most immature version of a peptide/protein hormone; eventually becomes prohormone then hormone

aromatase

an enzyme involved in enzymatic conversion of many androgens into estrogens; cannot act upon Dihydrotestosterone (DHT)

5 alpha-reductase

an enzyme involved in enzymatic conversion of weak androgens into more potent androgens

hormone response element (HRE)

the specific DNA element(s) that a steroid hormone binds to

positive feedback loop

increased stimulus causes an increase in hormone release

negative feedback

increased stimulus causes a decrease in hormone release

anterior pituitary gland

releases a tropic factor after receiving a release factor; tropic factor targets endocrine gland

posterior pituitary gland

contains neurosecretory cell terminals that store and release oxytocin and vasopressin (produced in the hypothalamus); neural signal triggers release of oxytocin and vasopressin

dimorphism

when a trait is expressed differently in males and females of a species

critical period

specific window(s) of time where hormones act to impact behavior

activational effects

hormones act on structures that were previously organized to elicit behavior; transient effects, only effective as long as the hormone is present

social play

animals interacting with others of a similar age

sexual play

mounting or pinning behavior without sexual purpose

locomotor play

movement around the environment without purpose

object play

manipulation of an object