Unit 2: Biological Bases of Behavior

Neurons

the basic building block of our nervous system, also known as a nerve cell

dendrites

a neuron’s bushy branching extensions that recieve messages/info and conduct impulses toward the cell body

axon

the neuron extension that passes the message recieved from dendrites through its branches to other neurons/muscles/glands

What recieves the message in our nervous system?

Dendrites

What passes the message in our nervous system?

Axons

myelin sheath

a fatty tissue layer which holds axons and speeds up their imuplses

degeneration of the myelin sheath can cause:

multiple scolorisis as communication to muscles slows down and leads to loss of muscle control

nuerons fire impulses which are called:

the action potential

action potential

a nueral impulse, or a brief electrical charge which travels down an axon

when do neurons transmit messages?

when stimulated by signals from our sense or triggered by chemical signals from neighboring neurons

the terminal branches of an axon…

forms junctions with other cells

neural impulse

the electrical signal traveling down the axon otherwise known as the action potential

axons pass messages….

away from the cell body to other neurons/muscles/glands

the fluid outside an axon’s membrane consists of ____ charged ions

postive

the resting axon’s fluid interior consists of ___________ ions.

negative

resting potential

the positive outside and negative inside charge ions

the axons surface is…..

selectivley permeable

refractory period

the period of inactivity after a neuron has fired where the neuron pumps positive charged sdodium ions back outside

increasing the level of stimulation above the threshold will not _________ the neural pulse’s intensity

increase

a neurons reaction is

an all or nothing response

how does a strong stimulus affect a neural impulse?

it doesn’t change the strength or speed but it can trigger MORE neurons to activate

what are the main components of a neuron?

the cell body, dendrites, axons, myelin sheaths, terminal branches

threshold

the level of stimulation required to trigger a neural impulse

all or nothing reponse

a neurons reacitino is either full strength firing or not firing at all

synapse

the meeting point between two neurons

synaptic gap/cleft

the tiny gap between the meeting point of two neurons (synpases)

neurotransmitters

chemical messengers which cross between the synaptic gap between two neurons and bind to the receptor site

reputake

when the sending neurons reabsorbs excess neurotransmitters

how many neurotransmitters can a particular brain pathway use?

one or two

endorphins

(morphine within), natural opiate like neutrotrasmittors linked to pain control and pleasure

what can overflooding the brain with artifical opiates do?

cause the brain to stop producing their own natural endorphins

agonist

molecules that are similar enough to a neurotransmittor to simtulte a response by binding to a receptor site

antagonists

molecuels that blocks a neurotransmitter response by binding to receptors

neurotransmitters are produced

in the body

drugs and chemicals can have what effects on a neurotransmittor?

angonistic or antagonisitc

How do neurons communit with each other?

What happen if received neuron signal exceed a maximum threshold?

the neuron fires and trasmits an electrical impulse down its axon by a chemistry to electricity process

when action potentials reach the end of an axon they…

stimulate the release of neurotransmitters

what happens if incoming signals from one axon to another are strong enough?

the receiving neuron generates its own action potential and relays the message to other cells

agonists ________ by mimikicing neurotransimiter or blocking their reputake

excite

nervous system

the body’s speedy, electrochemical communication enetwork which consists of all of the nerve cells for the peripheral and central nervous system

central nervous system (CNS)

the brain and spinal cord

peripheral nervous system (PNS)

the sensory and motto neurons that connect the central nervous

synapse

the meeting point between two neurons

synaptic gap

the gap between two neurons

reputake

the reabsorbtion of neurotransmitters back into the sending neuron

function of Serotonin

MOOD

affects mood, hunger, sleep, and arousal

contributes to well-being and happiness

undersupply of serotonin can cause:

depression

Function of Dopamine

PLEASURE

influences movement, learning, attention, addiction, motivation and emotion

causes people to repeat behaviors

Oversupply of Dopamine

schiozphrenia

Undersupply of Dopamine

tremors and decreased mobility in Parkinson’s disease and ADHD

Function of Acetylcholine (ACh)

LEARNING
activates muscle action, learning, and memory

What happens when ACh neurons detoriate?

Alzhiemers disease

function of norepinephrine

CONCENTRATION
helps control alertness and arousal by contracting blood vessels

undersupply of norepinephrine

depressed moods and ADHD-like attention problems

function of Gamma-Aminobutyric Acid (GABA)

CALMING
a major INHIBATORY neurotrasmitter, calms firing nerves in CNS

undersupply of GABA

linked to sezuires, tremors, and insomnia

is GABA inhibatory or excitatory?

inhibatory

Function of Glutamate

MEMORY

A major EXCITORY neurotrasmitter, very common and involved in memory and learning

oversupply of Glutamate

overstimulates the brain producing migranes and seizures

why do some people avoid MSG

becausde it can overstimulate the brain

function of Substance P

involved in pain perception and immune response

oversupply of Substance p

chronic pain

endorphins

natural opiate like neurotransmitters linked to pain control and pleasure

why can injecting artifical endorphins be bad?

the brain can stop producing neurotransmitters naturally

drugs and chemicals affect brain synpases by

inhibiting or exciting a neurons firing

agonist molecules

stimulates and activates a response by binding to receptors and micking the effects of the neurotransmitter

what types of molecules excite?

agonist molecules

peripheral nervous system

the sensory and motor neurons that connect our CNS to the rest of our body

purpose of PNS

gathers info and transmits CNS decisions to other body parts

central nervous system

the brain and spinal cord

what is our body’s decision maker

CNS

the PNS consists of

the somatic and autonomic nervous system

somatic nervous system

volunatry control of our skeletal muscles

skeletal nervous system

somatic nervous system

autonomic nervous system

controls the autoregulated action of our gland and internal organs

what category consists of sympathetic and parasympathetic

autonomic nervous system

sympathetic nervous system

arouses the body and expends energy in stressful situations

parasympatheic

calms the body down and conserves energy

sensory neurons

afferent neurons, carry incoming info from tissues and sensory receptors to the CNS

motor neurons

efferent neurons, carry outgoing info from CNS to the muscles and glands

what neurons are efferent

motor

which neurons are afferent?

sensory neurons

which neurons receive signals?

sensory or afferent neurons

endocrine system

a set of glands that secretes hormones into the bloodstream

pituitary gland

located in the core of the brain, controlled by the hypothalamus

• influences the release of many hormones, regulates growth, is considered a master gland, and controls all other glands

hypothalamus

region of brain which controls the pituitary gland

parathyroid

helps regulate calcium levels

thyroid

affects metabolism

adrenal glands

sit above the kidneys, triggers flight or fight response, secretes epinephrine and norepinephrine (adrenaline and noadrenaline)

pancreas

regulates sugar levels in blood

testis

secretes male sex hormones

ovary

secretes female sex hormones

adrenaline

secreted by the adrenal glands, responsible for arousal and the fight/flight response, plays a role in emotinoal memory foundation

Cortisol

Secreted by the adrenal glands; helps control blood sugar levels, regulate metabolism, reduce inflammation and assist with memory formation

Melatonin

Secreted by the pineal gland; signals the relaxation and lower body temperature that help with a restful sleep

Neuropeptide Y

Produced by the hypothalamus and acts as a neurotransmitter in the brain

• Stimulates food intake, reduces anxiety and stress, reduces pain perception, affects the circadian rhythm. 

• Higher levels of NPY linked with higher levels of resilience.

Oxytocin

Produced by the hypothalamus and secreted by the pituitary gland.  When it affects the brain, it acts as a neurotransmitter.  Plays a role in mother-child attachment; believed to play a role in social bonding and trust between people.

Testosterone

Produced by the testes; plays a facilitative role in aggressive behaviour -doesn't cause aggression, but higher levels of testosterone result in higher levels of aggression.

lesion

destruction of tissue