PNB Quiz 10 - Central Nervous System

CNS

brain and spinal cord (97%)

PNS

all other nervous tissue

groups of neuronal cell bodies - CNS

nuclei (gray matter)

groups of neuronal cell bodies - PNS

ganglia

bundles of axons - CNS

tracts/fibers (white matter)

bundles of axons - PNS

nerves

4 protections of the brain

skin, cranial bones, cranial meninges, cerebrospinal fluid

cranial meninges description

protective layer of tissue that surrounds brain and spinal cord

cranial meninges functions

provide support, cushion CNS, help circulate CSF

3 cranial meninges

dura mater, arachnoid mater, pia mater

dura mater

tough durable outer layer, just beneath skull — provides strong protection

arachnoid mater

thin fibrous, filamentous mesh, web-like middle layer - contains subarachnoid space, which holds CSF

pia mater

very thin and soft layer, sticks tightly to brain/spinal cord — warps around bumps and grooves of CNS

3 functions of CSF

homeostatic regulation of ions and nutrients, support, immune functions

CSF - homeostatic regulation description

CSF delivers nutrients (glucose) and maintains proper ion balance for neurons to function

CSF - support description

cushions and protects the brain and spinal cord from impact and injury

CSF - immune functions

helps remove waste and contains immune cells to protect the CNS from infection

ventricles description

cavities within the brain that produce and store CSF

ventricles flow path

1. CSF moves through subarachnoid space around the brain and spinal cord

2. excess CSF drains through arachnoid villi into the dural venous sinuses

CSF production and location

produced by the ependymal cells in the chloroid plexus, which is located in the brain’s ventricles

ependymal cells

type of glial cell that lines the ventricles of the brain and central canal of spinal cord - produce CSF and help it circulate

choroid plexus

network of ependymal cells and blood vessels found inside each ventricle of the brain - main site where CSF is produced

blood-brain barrier structure

endothelial cells of brain microvessels with tight junctions

allows - lipophilic, nonpolar, gases, water

blood-brain barrier function

control molecular traffic (block toxins/harmful substances), ion homeostasis (maintain proper ion balance for neurons), low protein environment (prevents unwanted cell growth and proliferation)

blood-brain barrier purpose

separates the blood from the brain’s extracellular fluid, keeping harmful substances out while allowing essential nutrients in

metabolic needs of the brain - 2

oxygen and glucose

metabolic needs of the brain - oxygen

• transported: through blood supply - receives 15% of blood pumped by heart at rest

• purpose: supports high energy demand for neuronal activity

metabolic needs of the brain - glucose

• transported: membrane transporters move from plasma into brain interstitial fluid

• purpose: main energy source - consumes 50% of body’s glucose

importance: low glucose (hypoglycemia) can cause confusion, unconsciousness, and deth

blood movement to/from brain - 2 types

arterial - supply, venous - return

arterial supply - 3 parts

internal carotid arteries, vertebral arteries, circle of willis

internal carotid arteries

main arteries supplying the anterior and middle portions of the brain

vertebral arteries

travel up the spine and supply the posterior brain, including brainstem and cerebellum

circle of willis

circular arterial network at the base of the brain that provides backup routes for blood flow in case of blockage

venous return - jugular veins

major veins that drain deoxygenated blood from the brain back to the heart

important regions of the brain

cerebrum, cerebellum, brainstem, diencephalon

cerebrum

responsible for higher brain functions (thinking, reasoning, memory)

diencephalon

controls homeostasis (hunger, thirst, temp, hormone regulation)

brainstem

acts as autonomic/reflex center (breathing, heart rate, reflexes)

cerebellum

coordinates movement and balance

gyrus (gyri)

raised ridges or folds on the brain surface

sulcus (sulci)

shallow grooves between the gyri

why is the brain organized with sulci and gyri?

to increase SA of the cerebral cortex, allowing more neurons in a limited space

longitudinal fissure

deep groove that separates the left and right cerebral hemisphere

cerebral hemispheres

two halves of the cerebrum, each controlling opposite sides of the body

transverse fissure

separates the cerebrum from the cerebellum

lateral fissure

separates the frontal and parietal lobes from the temporal lobe

central sulcus

groove separating the parietal lobe from the frontal lobe - important landmark for motor and sensory areas

lobes of the cerebrum

frontal, parietal, occipital, temporal

frontal lobe function

hypothesis generation + problem-solving, planning and organizing strategies, personality and emotional regulation, motor control

parietal lobe function

somatosensory processing (touch, temp, pain) and integration, spatial awareness + perception

occipital lobe function

processing/integration/interpretation of vision, interprets visual stimuli/stores visual memories

temporal lobe function

hearing (processes auditory info), language comprehension (understanding spoken + written language), memory formation and retrieval (helps store + recall memories)

contralateral control

each cerebral hemisphere controls the opposite side of the body

where is gray matter located - 2 main

cerebral cortex and the basal (nuclei) ganglia

cerebral cortex (gray matter)

outer layer of the cerebrum, involved in higher brain functions

basal (nuclei) ganglia (gray matter)

clusters of neurons inside the brain that help control movement

white matter - 3 types of fibers

commissural, projection, association

commissural fibers (white matter)

connect the two cerebral hemispheres

projection fibers (white matter)

connect the cerebrum to other regions of the CNS

association fibers (white matter)

connect areas within the same cerebral hemisphere

frontal lobe key parts

precentral motor cortex (precentral gyrus), broca’s area, olfactory bulb

precentral motor cortex (precentral gyrus) - frontal lobe

just anterior to central sulcus - when stimulated, specific body parts move (controls voluntary movement)

broca’s area - frontal lobe

usually in left frontal lobe - controls speech production

olfactory bulb - frontal lobe

at the base of the frontal lobe - odor perception (smell)

parietal lobe key parts

primary somatosensory cortex (postcentral gyrus), somatosensory association cortex

primary somatosensory cortex (postcentral gyrus) - parietal lobe

processes incoming sensory stimuli

somatosensory association cortex - parietal lobe

integrates + interprets sensory information

motor + sensory cortex homunculus

each part of the body has a specific area (“real estate”) in the motor + sensory cortex

relationship of motor + sensory cortex homunculus

the size of the cortical area reflects the level of fine motor control or sensory sensitivity, not the physical size of the body part

temporal lobe key parts

primary auditory cortex and wernicke’s area

primary auditory cortex - temporal lobe

receives and processes sound information

wernicke’s area - temporal lobe

critical for language comprehension

occipital lobe key parts

primary visual cortex and visual association area

primary visual cortex - occipital lobe

receives and processes raw visual input

visual association area - occipital lobe

interprets information from the primary visual cortex (2-D sketches, shapes, objects)

subcortical structures

basal nuclei, limbic components (hippocampus, amygdala)

basal nuclei (ganglia) function

motor control - modulate and refine motor movements; support semiautomatic end subconscious motions

parts of basal nuclei - 3

caudate nucleus, putamen, globus pallidus

caudate nucleus - basal nuclei

helps plan and execute smooth voluntary movements

putamen - basal nuclei

regulates movement amplitude and preparation

globus pallidus - basal nuclei

sends inhibitory signals to control unwanted movements

limbic components function

emotions and memory

limbic components parts

hippocampus and amygdala

hippocampus - limbic components

critical for memory formation and retrieval

amygdala - limbic components

processes emotion, especially fear and pleasure responses

diencephalon location

between cerebral hemispheres and brainstem

diencephalon function

sensory relay, autonomic control, endocrine regulation

diencephalon parts

epithalamus, thalamus, hypothalamus

epithalamus - diencephalon

posterior/superior - pineal gland - secretes melatonin to regulate circadian rhythm — connects limbic system with other brain regions

thalamus - diencephalon

superior - sensory relay (except smell), process motor signals + contributes to consciousness, principal + final relay for sensory info to the cerebral cortex — “switchboard”

hypothalamus - diencephalon

inferior/anterior - maintains homeostasis, controls endocrine system via pituitary gland, coordinates autonomic nervous system

hypothalamus 6 functions

• master control of autonomic nervous system

• master control of the endocrine system

• regulation of body temperature

• control of emotional behavior

• control of food/water intake

• regulation of sleep-wake (circadian) rhythms

brainstem broad functions

contains autonomic and reflex center essential for survival, acts as bidirectional passageway for all tracts between the cerebrum + spinal cord, houses nuclei of many cranial nerves

brainstem key structures

midbrain (mesencephalon), pons, medulla

midbrain key parts

cerebral peduncles and corpora quadrigemina (superior and inferior colliculi)

cerebral peduncles (pyramidal tracts) (midbrain)

carry descending motor information from the cerebrum to the spinal cord

corpora quadrigemina (midbrain)

• superior colliculi - visual reflexes (ie. tracking movement)

• inferior colliculi - auditory reflexes (ie. startle response to sound)

medulla key parts

cardiovascular + respiratory centers, cranial nerve nuclei, pyramids

cardiovascular + respiratory centers (medulla)

regulate heart rate, blood pressure, and breathing

cranial nerve nuclei (medulla)

nuclei for cranial nerves passing through the medulla