DAT BIOL - the nervous system

neuron

The funtional unit of the nervous system

soma

the neuron cell body, the nucleated region

Dendrites

processes for receiving signals from neighboring atoms

Axon

process for sending signals to neighboring neurons

Axon terminals

Site of signal transmission

Axon hillock

Site of connection between the soma and the axon

Myelin sheath

Fatty insulation of the acon which accelerates action potential propegation

Nodes of ranvier

gaps in the myelin sheath in whoch action potential can jump from gap to gap

Oligodendrocytes

create the myelin sheath in the CNS

Schwann cells

create myelin sheath in PNS

action potential

a rapid change in the membrane potential that exists across a membrane

action potential

a rapid change in the membrane potential that exists across a membrane

goverened by relative ion ratios in the intracellular and extracellular spaces

What ions are involved in neuron action potentials

sodium and potasium,

What is the resting state potential

-70mV, voltage is more negative inside than it is outside

What ions are being pumped in the resting state

SALTED BANANAS

3 Na+ out 2K+ in

using sodium potassium ATPase pumps

What is the neuron threshold

-55mV, stimulus causes some Na+ to go back into the cell

Depolarization

-55 mV results in a voltage gates Na+ channel opening, allowing a large influx of NA+ into the cell, with K+ channels closing

repolarization

Transition from a more positive depolarized membrane potential to a more negative repolarized membrane potential

What happens in the cell during repolarization

a volatge gated K+ channgel allows K+ out of the cell

Na+ IONS CLOSE AND ARE INNACTIVE

Hyper polarization

a membrane potential is even more negative than the resting potential

what happens during Hyper polarization

The sodium potastium atpase starts taking over to counter the voltage gated potassium channels

Refractory period

during hyperpolarization, phase where it is very diffiult or imposible to trigger another action potential

Why does hyperpolarization go so negative

Due to the fact that voltage gated potassium ion channels take a while to close

Absolute refractory period

Na+ channels are innactivated as K+ channels continue to repolarize the membranes

Relative refractory period

DURING HYPERPOLARIZATION

Very difficult to trigger a second action potential , in which Na+ channels are closed but not inactivated

Synaptic transmission

The transmission of chemical signals from one neuron to another across an interneuron space called a synapse using teurotransmitters

Synapse

The space between two neurons, including the presynaptic and postsynaptic neurons

Presynaptic neurons

responsible for sending the signal and releasing NTs into the synaptic cleft (AKA SYNAPTIC TERMINAL)

Synaptic cleft

The zone that exists between two neurons, not including either neurons

Postsynaptic neurons

responsible for signal reception and interacting with NTs

synaptic vesicles

Responsible for the transport of NTs from the axon to the synaptic cleft

Neurotransmitters

messenger molecules that are released by the presynaptic neuron and received by the postsynaptic neuron

Post synaptic ligand gated Ion channels

Directly responsible for the binding of free NTs at the post synaptic neuron

How are neurotransmitters released

Upon receiving an action potential, a large influx in Ca2+ by voltage gated Ion channels triggers exocytosis of synaptic vescicles

how are NTs receieved

NTs cross the synapse and are received at ligand gated ion channels of the postsynaptic neuron , causing graded potentials

Graded potentials

produced at the post-synaptic membrane, can be excitatory (depolarization) or inhibitory (hyperpolarization)

Exitatory postsynaptic potentials

graded potential that depolarizes the membrane and opens Na+ channels

inhibitory postsynaptic potentials

graded potential that polarizes the membrane and opens K+ channels

Summation of Graded potentiaals

all graded potentials summate at the axon hillock, potentially reaching that -55 threshold

Glutamate

the main ENT of the CNS

ENT

Dopamine

ENT

that is involved in reward of motivated behavior

Epinephrine and norepinephrine

Involved in the fight or flight response

reroute blood flow to the most critical parts of the body

ENT

Catecholamines

dopamine, epinephrine, and norepinephrine

Acetylcholine

The most common NT in the muscular system, signals to muscle fibers by binding to ligand gated sodium channels

ENT

Mnemonic to remember ENTs

good dogs eat apples IN ORDER OF PREVAENCE (not really, only glutamate)

Glutamate

epinephrine/norepinephrine

Acetylcholine

GABA

main INT of the CNS

Glycine

INT of the CNS

serotonin

INT of the brain

mnemonic for INTs

Good Guys Suck

Central nervous system

Brain and spinal cord

Peripheral nervous system

nerves branching off the CNS

cerebral cortex

The largest, outermost, deeply grooved portion of the brain

Frontal lobe

Higher level functioning, decision making, problem solving, attention and concentration

Temporal lobe

responsible for speech and hearing

occipital lobe

responsible for vision

parietal lobe

responsible for spatial perception and sensation

Cerebellum

Responsible for coordination of movement

Brain stem

involved in the control in automatic functions

made up of midbrain, medulla and pons + reticular formations

midbrain

In the brain stem

Responsible for the relay of senses to other parts of the brain

Pons

Responsible for the relay of messages between the forebrain, cerebellum, and medulla

medulla oblongata

part of the brainstem that controls RATES , heart pressure, and senses toxins

Reticular formations

Neurons that exist throughout the brainstem, responsible for cortical arousal and consciousness

Limbic system

Responsible for emotion, memory, learning and motivation

consists of the thalamus, hypothalamus, hippocampus, and amygdyla

Thalamus

in the limbic system, relays sensory and motor signals from the boddy to the brain

Hypothalamus

in the limbic system, regulates bodily hormones

Hippocampus

in the limbic system, responsible for memory

amygdala

resposible for emotion of scents

Spinal cord

nervous tissue that connect the brain to the body

Sensory (afferent) neurons

Relay signals to the spinal cord and eventually the brain via the dorsal roots

AFTER THERE IS A SIGNAL

motor (efferent) neurons

relay signals from the brain to the muscles via ventral roots

EFFECT CHANGE

Somatic nervous system

part of the peripheral nervous system, involved in voluntary actions

Autonomic nervous system

part of the peripheral nervous system, involved in involuntary actions

Mechanoreceptors

Responsible for reception of mechanical stimuli

Nociceptors

Responsible for reception of pain stimuli

Thermoreceptors

Responsible for reception of stimuli related to changes in temperature

Chemoreceptors

chemical stimuli

Electroreceptors

Responsible for reception of light, electrical, and magnetic stimuli

What is the autonomic nervous system split into

the parasympathetic nervous system and the sympathetic nervous system

Sympathetic Nervous System

Responsible for aiding the “fight or flight response”

Effect that SNS has on sugar

Release of sugar into the blood (increased energy)

Effect that SNS has on heart rate

Increased heart rate (increased oxygen delivery to the brain and to muscles)

Effect that SNS has on blood vessels

Vasodilation of skeletal blood vessels, vasoconstriction of the digestive system

Effect that SNS has on lungs

Dilation of bronchi and bronchioles (more oxygen into the lungs)

Effect that SNS has on pupils

Dilation of pupils (more light and visual information for the brain)

Parasympathetic Nervous System

Responsible for relaxing the body out of a sympathetic state (rest and digest)

how do parasympathetic effects occur

via the vagus nerve

Parasympathetic system effect on muscles

Relaxation of muscles

Parasympathetic system effect on heart rate

Decreased heart rate

Parasympathetic system effect on GI activity

Increase in gastrointestinal activity

parasympathetic system effect on homeostasis

it is maintained

Ganglion

a cluster of nerve cell bodies in the Peripheral nervous system synapsing between preganglionic and postganglionic neurons

preganglionic neuron

Neuron coming from the CNS that enters the ganglia

postganglionic neuron

Neuron coming from the ganglia that exits to effector organs

Sympathetic nervous system ganglion lengths

Short preganglionic neuron, long postganglionic neurons

What is released from the preganglionic neuron in the Sympathetic nervous system

Acetylcholine, short

What is released from the postganglionic neuron in the Sympathetic nervous system

norepinephrine and epineprine, long

paraympathetic nervous system ganglion lengths

long preganglionic neuron, short postganglionic neurons

What is released from the preganglionic neuron in the parasympathetic nervous system

acetylcholine

What is released from the postganglionic neuron in the parasympathetic nervous system

acetylcholine

Where can the preganglionic neuron release acetylcholine into in the sympathetic nervous system

into the adrenal medulla