Chapter 2: Biological Basis of Behaviour

instinctual behaviours

behaviours that are hard-coded and shaped by genetics

adaptive traits

traits or behaviours that have been selected for because they promote reproductive success

heritability

the proportion of variation in a trait/phenotype that is due to variation in the genotype

epigenetics

changes that affect how genes work that don’t involve changing the actual nucleotide content

methylation

mechanism of epigenetics in which a methyl group is added to nucleotides, which silences the gene (shuts down expression)

first trimester

stage of pregnancy in which the major structures of the fetus are forming

second trimester

stage of pregnancy in which the fetus’s major organs/structures have formed and growing is the main priority

third trimester

stage of pregnancy in which the fetus grows and finalizes preparations for the outside world

patellar reflex

reflex in which your leg will jerk in response to your knee being hit

palmar grasp reflex

reflex in babies where if you stroke the palm of their hand, they will grab onto your finger

rooting reflex

feeding reflex in babies where if a baby’s mouth or cheek is touched by something, it will search for the object that brushed by it

sucking reflex

feeding reflex in babies where if something grazes a baby’s mouth, it will automatically start making sucking motions

Moro reflex

reflex in babies in which they startle in response to sudden movement or loud sounds by extending their arms and legs, pulling them back in, and throwing their head back before crying

Babinski reflex

reflex in babies in which if the bottom of their foot is stroked, they will extend their toes outward

adolescence

transition from childhood to adulthood

puberty

process of biological changes that happen during adolescence

endocrine system

network of organs distributed throughout the body that secrete signalling molecules (hormones) into the bloodstream

direct hormones

signalling molecules that cause their target cells to make direct changes in some physiological function

tropic hormones

signalling molecules that cause their target cells to release hormones

hypothalamus

structure in the endocrine system that converts input from the nervous system into endocrine signals, also releases various tropic hormones

\*\*releases GnRH, CRF, and TRH

GnRH

tropic hormone that travels from the hypothalamus to the anterior pituitary to trigger the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) → tropic hormone that stimulates the release of the hormones that regulate reproduction

CRF

tropic hormone that travels from the hypothalamus to the anterior pituitary to trigger the release of adrenocorticotropic hormone (ACTH)

ACTH

tropic hormone that travels from the anterior pituitary to the adrenal glands to trigger the release of cortisol

TRH

tropic hormone that travels from the hypothalamus to the anterior pituitary to trigger the release of thyroid-stimulating hormone (TSH), which promotes thyroid hormone to be released by the thyroid gland

anterior pituitary gland

structure in the endocrine system that is located below the hypothalamus and receives hypothalamic hormonal input through the hypophyseal portal system

\*\*releases LH, FSH, ACTH, TSH, prolactin, endorphins, and growth hormone

hypophyseal portal system

system of blood vessels connecting the hypothalamus to the anterior pituitary in the endocrine system

posterior pituitary gland

structure in the endocrine system that receives input from the hypothalamus in the form of neuronal signals

\*\*releases ADH and oxytocin

thyroid gland

structure in the endocrine system found in the throat that releases calcitonin and thyroid hormone

adrenal glands

structures in the endocrine system found on top of the kidneys and divided into two distinct portions (cortex and medulla)

adrenal cortex

portion of the adrenal gland that secretes steroid hormones such as glucocorticoids and cortisol

adrenal medulla

portion of the adrenal gland that secretes epinephrine and norepinephrine, which are involved in the acute stress response

ovaries

structures in the endocrine system that release estrogen

testes

structures in the endocrine system that release testosterone

oxytocin

hormone secreted by the posterior pituitary gland that has roles in uterine contractions, social bonding, and mood

prolactin

hormone secreted by the anterior pituitary gland that has roles in lactation and modulating the stress response, anxiety, and depression

melatonin

hormone secreted by the pineal gland of the brain that has roles in inducing sleep

leptin

hormone involved in hunger that reduces hunger and tells the body to stop eating → primarily released by adipose/fat cells and acts on the hypothalamus

ghrelin

hormone involved in hunger that promotes hunger → released by cells in the gastrointestinal tract and acts on the hypothalamis

neuropeptide Y

hormone involved in hunger that stimulated appetite to increase food intake

epinephrine

hormones secreted by the adrenal medulla that are responsible for the acute stress (fight or flight) response

cortisol

hormone secreted by the adrenal cortex that is responsible for the chromic/long-term stress response

thyroid hormone

hormone released by the thyroid gland that has roles in metabolism and neurological development

hypothyroidism

condition in which abnormally low levels of thyroid hormone cause fatigue and depression

hyperthyroidism

condition in which abnormally high levels of thyroid hormone cause irritability

reflex arcs

simple neural pathways that control reflexes

neurons

cells of the nervous system

depolarization

increase in electric potential (potential becomes less negative)

synapse

space between one neuron and another neuron or its target cell

sensory neurons

neurons that carry information about stimuli to the central nervous system

afferent neurons

sensory neurons

motor neurons

neurons that carry signals to react from the central nervous system to the target cell

efferent neurons

motor neurons

excitatory neurotransmitters

neurotransmitters that depolarize the target neuron → making it more likely to generate an action potential

inhibitory neurotransmitters

neurotransmitters that hyperpolarize the target neuron → making it less likely to generate an action potential

acetylcholine

neurotransmitter responsible for activating muscle contraction at the neuromuscular junction and has a role in the ‘rest-digest’ functions of the parasympathetic nervous system

glutamate

excitatory neurotransmitter → depolarizes postsynaptic neurons to push them closer to the action potential threshold

GABA

inhibitory neurotransmitter → hyperpolarizes postsynaptic neurons to push them further away from the action potential threshold

dopamine

neurotransmitter involved in reward pathways and mediating certain motor functions

serotonin

neurotransmitter involved in mood regulation, appetite, sleep, and regulation of intenstinal movement in the gastrointestinal tract

endorphins

neurotransmitters that suppress pain and can cause a euphoric response

norepinephrine

neurotransmitter involved in the acute stress (fight or flight) response, allowing the heart rate and blood pressure to elevate → involved in the autonomic nervous system

epinephrine

neurotransmitter with similar roles and effects to norepinephrine

\*\*also called adrenaline

agonist

compound that activates a certain receptor, causing some kind of response

antagonist

compound that bind to a receptor, blocking it, so that it is not activated and no response is triggered

central nervous system

system that consists of the brain and spinal cord

peripheral nervous system

section of the nervous system containing everything but the brain and spinal cord

somatic nervous system

section of the peripheral nervous system that is responsible for carrying out voluntary activities

autonomic nervous system

section of the peripheral nervous system that is responsible for unconscious activities

sympathetic nervous system

section of the autonomic nervous system that is responsible for the fight or flight (acute stress) response

\*\*dilates pupils and bronchioles, raises heart rate, and inhibits the activity of the digestive organs

parasympathetic nervous system

section of the autonomic nervous system that is responsible for the rest and digest response

\*\*constricts pupils and bronchioles, reduces heart rate, and stimulates the activity of the digestive organs

enteric nervous system

section of the autonomic nervous system that regulates the activity of the gut

hindbrain

part of the central nervous system consisting of the cerebellum, pons, and medulla oblongata

midbrain

part of the central nervous system consisting of the substantia nigra, superior colliculus, and inferior colliculus

brainstem

part of the central nervous system consisting of the midbran, medulla oblongata, and pons

forebrain

part of the central nervous system consisting of the diencephalon and the telencephalon

diencephalon

part of the central nervous system consisting of the thalamus, hypothalamus, posterior pituitary gland, and pineal gland

cerebellum

structure in the hindbrain responsible for coordinated movement

medulla oblongata

structure in the hindbrain responsible for autonomic functions (ie. breathing, heart rate, and blood pressure)

pons

structure in the hindbrain that acts as a relay station to coordinate signals from the hindbrain and the rest of the brain → also involved in sleep, respiration, swallowing, taste, bladder control, and balance

inferior colliculus

structure in the midbrain that helps process auditory information

superior colliculus

structure in the midbrain that helps process visual input

substantia nigra

structure in the midbrain responsible for using dopamine to help coordinate voluntary movements

reticular activating system

complex set of structures in the brain stem that is responsible for alertness and arousal

thalamus

structure in the forebrain that relays sensory and motor signals and regulates sleep and alertness

hypothalamus

bridge between the nervous and endocrine systems

hippocampus

structure in the brain that consolidates short term memory into long term memory

basal ganglia

group of subcortical nuclei that is involves in procedural and habitual learning as well as eye and other voluntary movements

limbic system

group of structures involved in emotion, memory, and motivation → made of the hypothalamus, thalamus, hippocampus, and amygdala

amygdala

structure in the brain that is involved in episodic memory, attention, and emotion

nucleus accumbens

structure in the brain that is involved in reward, motivation, and learning

frontal lobe

lobe involved in voluntary movement, memory processing, planning, motivation, and attention

parietal lobe

lobe involved in sensory processing

occipital lobe

lobe involved in vision

temporal lobe

lobe involved in meaning, making visual memories, attaching meaning to information, and language

broca’s area

structure in the frontal lobe of the brain that is involved in language production

wernicke’s area

structure in the temporal lobe that is involved in language comprehension

ventral

side of the spine that motor/efferent neurons are found

dorsal

side of the spine that sensory/afferent neurons are found

cervical spine

seven vertebrae in your neck

thoracic spine

twelve vertebrae in your middle back