kaitlyn PHR 936 Block 1 - Neuroanatomy and Neurobiology

lobes of the brain

frontal, parietal, occipital, temporal

frontal lobe

thinking

memory

behavior

movement

attention

impulse control

parietal lobe

somatosensation (touch)

language

occipital lobe

vision

reading

temporal lobe

hearing

learning

emotions

memory

visual processing

insula

5th cortical lobe deep within the brain

subconscious

sulcus

grooves between the gyri

gyrus

outwardly rounded ridges of the cortex

encephalization

the evolutionary process which results in increased brain mass, without corresponding changes in body size

- folds and grooves increase brain surface area

primary somatosensory cortex

the region of the anterior parietal lobe whose primary input is from the somatosensory system

primary motor cortex

the section of the frontal lobe responsible for voluntary movement (precentral gyrus)

limbic system

emotion center + learning/ memory

- means "border"

- contains: extended amygdala, hippocampus, pituitary, olfactory gland

extended amygdala

response and memory of emotions, especially fear

- located at the end of the hippocampus

- means "almond"

hippocampus

consolidation of new memories, short -> long term; emotions, navigation, spatial orientation, learning

- located in each temporal lobe

- means "seahorse"

basal ganglia

voluntary motor movements, procedural learning, habit learning, emotion, eye movement, cognition, addiction

- located at the base of the forebrain (middle of the brain)

connected to the cerebral cortex, thalamus, and brainstem

- means "pedestal knot"

- contains many parts

substantia nigra

eye movement, motor planning, reward-seeking, learning, addiction

- part of the basal ganglia

- means "black substance"

- nucleus consists of Pars Compacta (dopaminergic) and Pars Reticulata (GABAergic)

thalamus

relays information from all sensory receptors (not olfactory) to brain areas to be processed, regulation of sleep/wake

- located below the corpus callosum in the forebrain

- means "chamber"

- has 2 symmetrical halves on each side

hypothalamus

coordination center for: autonomic NS, pituitary activity, hunger, thirst, body temp regulation, sleep, emotional activity, maternal behavior

- located above the pituitary gland and below the thalamus

reaches in each temporal lobe

- means "under the chamber"

pituitary gland

endocrine gland at the base of the brain

hypothalamus talks to pituitary -> pituitary release appropriate hormone

- located below the hypothalamus

suprachiasmatic nucleus

circadian pacemaker "master oscillator", regulates pineal gland

- located in hypothalamus, above optic chasm

- means "nucleus above the optic chasm)

- consists of 20,000 neurons

pineal gland

secretion of melatonin, circadian rhythmicity

- located on midline of brain

- means "pine cone"

- only one!

- consists of pinealocytes

brain stem

connects the brain and spinal cord

- consists of the midbrain, pons, and medulla oblongata

midbrain

(brain stem)

sensory and motor information, eye movement

pons

(brain stem)

REM sleep, autonomic regulation

medulla oblongata

(brain stem)

blood pressure, breathing, heart rate, swallowing

cerebellum

motor control system, balance, posture, coordination of muscles, finely adjusted movement

- lower area of the brain , close to pons

- means "little brain"

- consists of 2 hemispheres, tightly folded layers of gray matter

corpus callosum

communication between hemispheres

- located between the left and right hemispheres; above thalamus, under cortex

- means "tough body"

- largest white matter structure

- consists of 200-250 million axonal projections

cerebroventricular system

controls the synthesis, release, internal circulation, and drainage of cerebrospinal fluid (CSF)

- lateral ventricles (pair) - largest surface area

- third ventricle - diencephalon

- fourth ventricle - between the pons and medulla/ cerebellum

cerebrospinal fluid (CSF)

a highly modified filtrate of plasma that is produced and released by epithelial cells in the choroid plexus

- the brain circulates a total volume of about 150 mL

- 700 mL is secreted each day in humans

- entire volume turns over every 5-7 hours

functions:

1. cushion and support the brain

2. regulation of ion composition/ hormone distribution

blood brain barrier

blood vessels (capillaries) that selectively let certain substances enter the brain tissue and keep other substances out

- 100 billion capillaries

- 100% of large molecule drugs and 98% of small molecules do NOT cross the BBB

functions:

- provide brain with O2/ glucose, clear waste, prevent xenobiotic entry, maintain brain homeostasis, protect from abrupt changes in peripheral blood

neurovascular unit

an active barrier consisting of influx transporters, efflux transporters, and metabolic enzymes in endothelial cells

cirumventricular organs

brain regions that are in close contact with CSF and must respond quickly to factors present in systemic circulation (fluid/ electrolyte balance, endocrine feedback, emesis)

- lack an organized BBB

what do all neurons do?

- detect and summate all incoming stimuli

- process and integrate the information received

- conduct an electrical signal along the cell

- transfer chemical information to other cells

dendrites

a neuron's bushy, branching extensions that receive messages and conduct impulses toward the cell body

- detect and summate all incoming stimuli

cell body (soma)

contains the nucleus and other parts of the cell needed to sustain its life

- process and integrate information receieved

axon

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands

- conduct an electrical signal along the cell

myelin sheath

covers the axon of some neurons and helps speed neural impulses

synapse

the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron

- transfer chemical information to other cells or tissues

gray matter

consists of the cell bodies and dendrites of neurons and glia

- pink outer layer

- sensory perception, muscle control, self-control, decision making, memory, data processing

white matter

consists of neuronal axons ensheathed in myelin

- learning and cognition

4 basic types of neurons

1. multipolar - motor neuron, most common in CNS

2. bipolar - eyes & ears, processes precise info

3. pseudo-unipolar - sensory neurons in PNS, important in pain

4. unipolar - mostly in invertebrates

ganglion

a collection of nerve cell bodies that are located outside the CNS

- autonomic ganglia, Trigeminal ganglia

nucleus

a collection of neuronal cell bodies that are located inside the CNS

- suprachiasmatic nucleus, nucleus acumbens

upper motor neurons

NCBs (nerve conduction bundles) in the motor control areas of the cerebral cortex or brainstem

- damage to upper motor neurons leads to excess muscular movement (spasticity)

lower motor neurons

neurons that directly innervate skeletal muscles

- somatic - NCBs in the spinal cord + presynaptic nerve terminals on skeletal muscle

> damage leads to muscular weakness and paralysis

- autonomic - NCBs in the spinal column + presynaptic nerve terminals on smooth muscle (vascular, glandular, lining of hollow organs)

- special visceral motor neurons - cranial nerves (facial movement)

motor neuron

location: motor cortex, brain stem, and spinal cord

composed of: long axons and dendrites

functions: project to spinal cord or effector organs (muscles, glands) and movement of muscles

sensory neuron

location: dorsal root ganglia, peripheral axons that extend to receptors in the periphery, central axon projections into the spinal cord

composed of: short axons, receptors, dendrites receiving information straight from the source, cell body is on the side

functions: response to external stimuli (touch, odor, taste, vision) and activate motor neurons

pyramidal neurons

location: hippocampus, cerebral cortex, amygdala

composed of: neuron with apical and basal dendritic branches

functions: synaptic integration and neuroplasticity

purkinje cells

GABAinergic neurons

location: cerebellum

composed of: neuron with many branching extensions

function: motor movement control

- needs to be very precise = many branches

action potential

a neural impulse; a brief electrical charge that travels down an axon

electrical neurotransmission

following sufficient excitatory stimulation of the neuron, an action potential is generated at the origin of the axon

chemical neurotransmission

when the action potential reaches the axon terminal, it stimulates the release of chemical neurotransmitters

sodium potassium ATPase

powered by ATP

carries 3 Na+ out and 2 K+ in

balances passive forces of diffusion

what is calcium's role in neurotransmission?

triggers neurotransmitter release

voltage-gated ion channels

transmembrane proteins important in electrical signaling of cells

- activity is regulated by the membrane potential of a cell

- open channels allow the movement of ions along an electrochemical gradient across cellular membranes

voltage-gated sodium channels

membrane proteins that open sodium channels in response to a sufficient voltage change, and initiate and transmit the action potential as Na+ enters through the channel

neuroglia

cells that support and protect neurons

can be in the CNS and PNS

CNS:

- ectodermal origin: astrocytes (BBB formation) and oligodendrocytes (myelin sheath)

- mesodermal origin: microglia (neuro-immune)

PNS:

- Schwann cells (myelin sheath)

astrocytes

glia cells (CNS)

"star-shaped cells"

location: whole brain

functions: part of the neurovascular unit (BBB), provide nutrients to nervous tissue, maintain ion balance, repair/ scarring process following traumatic injuries, synthesis and degradation of glutamate

microglia

glia cell (CNS)

primary immune cells of the CNS

location: whole brain

functions: overall brain maintenance, scavenge plaques/ damaged cells/ infectious agents

- they become activated when they detect pathogens

oligodentrocytes

glia cell (CNS)

"cells with a few branches"

location: whole brain

functions: support for axons, create myelin sheath for axons

Schwann cells

glia cell (PNS)

functions: create myelin sheath for axons

- can only wrap around ONE axon

mast cells

immune cell (WBC)

"master regulator" of the immune system

location: brain

functions: interact with astrocytes/ microglia/ BBB, neuroinflammation, brain injury, stress

leukocytes

immune cells (WBC)

location: brain

- enter brain through the BBB

functions: immune surveillance of the CNS, neuroinflammation