IB 131 Final Exam

What make up the CNS?

brain and spinal cord

What makes up the PNS

cranial nerves, spinal nerves, ganglia

What are three attributes of neurons

Longevity: live for a lifetime
Do not divide: fetal neurons lose ability to undergo mitosis
High metabolic rate: require abundant O2 and glucose

What is the cell body called in the CNS vs the PNS?

Nuclei (CNS)
Ganglia (PNS)

What are characteristics of sensory neurons?

Unipolar
Cell bodies in ganglia outside the CNS
Peripheral process: extends from sensory receptors
Central process: terminates in the CNS

What are characteristics of motor neurons?

Multipolar
Cell body in CNS
Form junctions with effector cells

What are characteristics of interneurons?

Multipolar
Confined to CNS
Link in chains

Oligodendrocytes

glial cell in the CNS that wrap axons in a myelin sheath
have multiple processes, each of which can wrap multiple axons

Schwann cells

glial cell in the PNS that wrap axons in concentric layers

Trigeminal neuralgia (tic douloureux)

recurring episodes of intense stabbing pain in forehead/top of skull, maxillary/cheek, lower jaw

Caused by demyelination of axons in sensory root of CN V

What is gray matter made of?

neuron cell bodies, dendrites, and unmyelinated axons, neuroglia

where synapses occur

centrally located

What is white matter made of?

myelinated axons

Endoneurium

surrounds individual axons and myelin, made from delicate CT

Perineurium

surround nerve fascicles, made from CT

Epineuronium

surround whole nerve, made frmo a tough fibrous sheath

What are the 4 regions of the brain?

cerebrum, diencephalon, brainstem (midbrain, pons, medulla), cerebellum

What are the 3 vesicles of the brain in a 4 week old embryo?

Prosencephalon: forebrain
Mesencephalon: midbrain
Rhombencephalon: hindbrain

What are the 5 vesicles of the brain in a 5 week old embryo?

Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myelencephalon

Telencephalon

cerebral hemispheres

Diencephalon

thalamus, hypothalamus, epithalamus

Mesencephalon

midbrain

Metencephalon

pons and cerebellum

Myelencephalon

medulla oblangata

Brain cortex

outer shell of gray matter of brain covering a core of white matter

Forebrain

telencephalon (cerebrum); diencephalon (thalamus, hypothalamus, epithalamus)

Hindbrain

medulla, pons, cerebellum

Lateral ventricles

A set of paired ventricles lying within the cerebral hemispheres

Third ventricle

the ventricle located in the center of the diencephalon

Fourth ventricle

the ventricle in the hindbrain, connects to the central canal of the spinal cord

Interventricular foramen

connects lateral ventricles to third ventricle

Cerebral aqueduct

connects the third and fourth ventricles, in the midbrain

What is the role of the brain stem?

passage way for all fiber tracts running between the cerebrum and spinal cord
10/12 CN attach to it
automatic behaviors for survival
integrates auditory and visual reflexes

Pyramids

in medulla oblongata
holds pyramidal tracts from cerebrum, control voluntary motor

Decussation of pyramids

crossover of corticospinal (motor) tracts

explains why motor control is contralateral

Olive

found in medulla oblongata

contains the inferior olivary nucleus

relay nuclei for proprioceptive to cerebellum

Reticular formation

contained in the core of the medulla

neurons that have long, branching axons, that spread to widely separated regions

nuclei centers that influence autonomic functions, such as cardiac, vasomotor, respiratory, hiccuping, sneezing, swallowing, coughing

ventral respiratory group (VRG)

A portion of the medulla oblongata that is responsible for modulating breathing

What CN travel through the medulla oblongata?

VIII, IX, X, XII

Inferior cerebellar peduncles

connect medulla to cerebellum

Middle cerebellar peduncles

connect pons to cerebellum

Fibers from the cerebellum to the cerebrum, coordinating fine motor movement

Pontine nuclei

the clusters of neurons that relay information from the cerebral cortex to the cerebellum

What CN pass through the pons?

V, VI, VII

Tectum

roof of the midbrain

Cerebral peduncles

connects midbrain and cerebrum
contains pyramidal tracts

Superior cerebral peduncles

connect midbrain to cerebellum

What CN pass through the midbrain?

III, IV

Corpora quadrigemina

located in the midbrain; contains reflex centers for vision and auditory reflexes

superior and inferior colliculi

Superioir Colliculi

nuclei in the midbrain that act in visual reflexes (peripheral vision)

Inferior Colliculi

nuclei in the midbrain that act in reflexive response to sound

Red nucleus

midbrain nucleus that controls autonomic motor functions (reticular formation)

Substantia nigra

an area of the midbrain that is involved in motor control and contains a large concentration of dopamine-producing neurons

functionally linked to the basal nuclei

Parkinson's disease

degeneration of substantia nigra

Mostly physical symptoms

Lewy bodies

abnormal protein deposits that form within the nucleus of cells in parts of the brain

Lewy body dementia

both physical and cognitive disabilities

Folia

folds of the cerebellum

Anterior and posterior lobes of the cerebellum

control trunk and limb movement

Flocculonodular lobe

division of the cerebellum that adjusts posture to maintain equilibrium, coordinate head and eye movement

Cerebellum Penduncles

thick tracts that link cerebellum with brain stem, cerebrum, and spinal cord

Cerebellum

smoothing and coordinating body movements, equilibrium, motor memory

What is the diencephalon composed of?

gray matter

What are the three paired structures in the diencephalon?

thalamus, hypothalamus, epithalamus

What CN pass through the diencephalon?

I, II

What is the function of the thalamus?

Contains a dozen major nuclei that act as relay center and directs impulses to cerebrum

gateway

VPL

Ventral posterolateral nucleus of the thalamus

General sensory

M. geniculate

nucleus of the thalamus that relays auditory input

L. geniculate

nucleus of the thalamus that relays visual information

What surrounds the hypothalamus?

between the optic chiasm and mammillary bodies
pituitary gland projects inferiorly

What is the function of the hypothalamus?

Contains about a dozen nuclei that serve as the main visceral control center of the body

ANS, emotions, body temperature, hunger, thirst, behavior, sleep/wake, endocrine, memory

Suprachaismatic nucleus

the pair of small nuclei in the hypothalamus above optic chiasma thought to be the regulation point of physiological circadian rhythms

Epithalamus

contains pineal gland
Secretes melatonin under the influence of the hypothalamus to aid in control of circadian rhythm

What percentage of brain mass does the cerebrum compose?

83

Fissures

deep grooves in the cerebrum

Transverse fissure

separates cerebrum from cerebellum

Longitudinal fissure

separates cerebral hemispheres

What are the 4 paired lobes of the cerebrum?

frontal, parietal, occipital temporal

Central sulcus

separates frontal and parietal lobes

Parieto-occipital sulcus

separates parietal and occipital lobes

Lateral sulcus

Separates temporal lobe from parietal and frontal lobes

Precentral gyrus

primary motor cortex
anterior to central sulcus

Postcentral gyrus

primary somatosensory cortex
posterior to central sulcus

What percent of brain mass is the cerebral cortex

40

What is the cerebral cortex composed of?

gray matter: enuron cell bodies, dendrites, short axons

Frontal lobe

primary motor cortex
plan, initiate, enact movement

Not fully developed in teen (decision making)

Parietal lobe

primary somatosensory cortex
conscious awareness, special awareness, understanding speech

Occipital lobe

visual cortex

Temporal lobe

auditory and olfactory cortex
Recognition, comprehension, emotion

Insula

region of the cerebral cortex
visual sensory cortex
taste and general

Primary somatosensory cortex

along the postcentral gyrus of the parietal lobe
conscious awareness of general somatic senses
spatial discrimination
Contralateral projection

Sensory homunculus

Demonstrates that the area of the cortex dedicated to the sensations of various body parts is proportional to how sensitive that part of the body is.

Primary motor cortex

precentral gyrus of the frontal lobe
Contains pyramidal cells that specifically control specific areas of the body

Pyramidal cells

large neurons of primary motor cortex

Somatotopy

Motor homunculus
all muscles of body can be mapped to area on primary motor cortex

Primary visual cortex

receives visual information from retinas contralaterally
first area to process visual input

Where is the primary visual cortex located?

deep within the calcarine sulcus in the occipital lobe

Where is the visual association area located?

surrounds the priamry visual cortex

What is the function of the visual association area?

processes visual information after the primary visual cortex
Analyzes form, color, movement

Ventral stream

"what pathway"; processes what the object is; colour, form; goes toward teh temporal lobe

Dorsal stream

The "where pathway" involved in processing an object's spatial location relative to the viewer
goes toward the parietal lobe

What is the function of the primary auditory cortex?

conscious awareness of sound
Impulses from inner ear transmitted here

Where is the primary auditory cortex located?

superior edge of temporal lobe