Chapter 3: Nervous System Organization

nuclei

clusters in the cortex that organize neurons

tracts

fiber pathways that form from the long-distance connections between neurons and cells

anatomical reference to body parts

rostrum (beak), caudum (tail), dorsum (superior), and ventrum (inferior)

anterior

structures that are in front

posterior

structures that are behind

lateral

structures that are at the side

medial

structures are at the center/between

coronal

a section that reveals a frontal view

horizontal

a section that reveals a dorsal view

sagittal

a section that reveals a medial view

ipsilateral

structures that lie on the same side of the nervous system and body (e.g. left arm is ipsilateral to the left leg)

contralateral

structures that lie on the opposite side of the nervous system and body (e.g. left arm is contralateral to the right leg)

bilateral

structures that lie in each hemisphere of the nervous system and body (e.g. the lungs are bilateral structures)

proximal

structures close to one another (e.g. the shoulder is proximal to the elbow)

distal

structures far away from one another (e.g. the hand is distal to the shoulder)

afferent

any movement towards a brain structure (e.g. sensory pathways that carry messages from the body towards the brain and spinal cord)

efferent

any movement away from a brain structure (e.g. motor pathways leading to the body from the brain and spinal cord)

precentra gyrus

a part of the brain responsible for motor ability

parasympathetic nerves

calming nerves that tell the organs when to rest and digest

sympathetic nerves

arousing nerves that tell the organs when to fight and flee

meninges

a triple-layered set of membranes within the bony case enclosing the CNS

dura mater

tough layer of tissue enclosing the brain in a loose sack

arachnoid membrane

a very thin sheet of delicate tissue that follows the brain’s contours

pia mater

a moderately tough tissue that clings to the brain’s surface

booid-brain barrier

protects the CNS by limiting the movement of chemicals from the rest of the body into it and by protecting it from toxic substances and infection.

astroglia

glial cells that stimulate the cells of capillaries to form tight junctions with one another to prevent many blood-borne substances from crossing from the capillaries into the CNS tissue

anterior cerebral artery (ACA)

irrigates the medial and dorsal parts of the cortex

middle cerebral artery (MCA)

irrigates the lateral surface of the cortex

posterior cerebral artery (PCA)

irrigates the ventral and posterior surfaces of the cortex

neural stem cell

a germinal cell that the brain originates in

progenitor cells

migrate and act as precursor cells

blasts

non dividing primitive nervous system cells 

sensory receptor

a cell that transduces sensory information into nervous system activity

bipolar neuron

a cell body with a dendrite on one side and an axon on the other (found in the retina)

somatosensory neuron

projects from a sensory receptor in the body into the spinal cord. its dendrite and axon are connected so messages don’t have to pass through the body, speeding up information conduction

interneurons

links up sensory and motor neuron activity in the CNS

motor neurons

located in the brainstem and spinal cord, and project to facial and body muscles (the final common path because all movement is produced through them)

gray matter

color comes from the capillaries and neuronal cell bodies that predominate there; this makes up the cortex

white matter

consists of axons that extend from these cell bodies to form connections with neurons in other brain areas

reticular matter

contains a mixture of cell bodies and axons which gives it a net-like appearance, or mottled gray and white.

ganglia

clusters (layers or nuclei) within the PNS

nerves

fibers and fiber pathways that enter and leave the CNS

ventricles

four prominent pockets of the hollow region in the tube of the brain; where CSF flows through; “lateral ventricles” (first and second) form C-shaped lakes underlying the cerebral cortex and third and fourth ventricles extend into the brainstem and spinal cord, and are connected by the cerebral aqueduct

dermatome

skin cut body segments that encircles the spinal column

posterior root

strands of fiber that converge from information being brought in by the body’s sensory receptors from afferent fibers

anterior root

strands of fiber that converge from information being brought out towards the muscles from the efferent fibers 

reflexes

specific movements elicited by specific forms of sensory stimulation.

flexion

reflexes that bring the limb toward the body and away from injury in response to pain and temperature

extension

reflexes that extend the limb outward, away from the body in response to fine touch and muscle receptors

cranial nerves

12 pairs that convey sensory (s) and motor (m) signals to and from the head. one set controls the left side, the other set controls the right (olfactory, optic, oculomotor, trochlear, trigeminal, abdunces, facial, auditory vestibular, glossopharyngeal, vagus, spinal accessory, and hypoglossal)

referred pain

pain that’s perceived as coming from the outer parts of the dermatome

brain stem

consists of the diencephalon, the midbrain, and the hindbrain

hindbrain

consists of the cerebellum, recticular formation, the pons, and the medulla

cerebellum

plays a role in motor coordination, motor learning, and may coordinate other mental processes

reticular formation

maintains “general arousal” or consciousness (RAS)

pons

bridges inputs from the cerebellum to the rest of the brain through its nuclei

medulla

regulates vital functions like breathing and the functioning of the cardiovascular system

midbrain

consists of the tectum and the tegmentum

tectum

a posterior sensory component, and the roof of the third ventricle.

superior colliculi

structure of the tectum that receives projections from the retina

inferior colliculi

structure of the tectum that receives projections from the ear

tegmentum

an anterior motor structure, and the floor of the third ventricle

substantia nigra

black substance that connects ot the forebrain and rewards behaviors such as approaching desired objects

periacqueductal gray matter (PAG)

controls species-typical behaviors (e.g. sexual) and modulates pain responses

diencephalon

consists of the hypothalamus, thalamus, and the epithalamus

hypothalamus

takes part in nearly all aspects of motivated behavior—feeding, sexual behavior, sleeping, temperature regulation, emotional behavior, and movement.

thalamus

serves as a hub for the cortex, which relays information through it, and other brain regions. lateral geniculate body (LGB) receives visual projections; medial geniculate body (MGB) receives auditory projections; and ventrolateral posterior nuclei (VLP) receives touch, pressure, pain, and temperature projections from the body

epithalamus

secretes melationin, which influences daily and seasonal body rhythms

habenula

regulates hunger and thirst

pineal gland

influences daily and seasonal biorhythms

forebrain

consist of the basal ganglia, the limbic system, and the neocortex

basal ganglia

a collection of nuclei that form a circuit with the cortex thats associated with movement and learning. includes the putamen, the globus pallidus, and the caudate nucleus

limbic system

plays a role in self-regulatory behaviors such as emotion, personal memories, spatial behavior, and social behavior. consists of the amygdala, the hippocampus, and the cingulate cortex

amygdala

participates in emotion

hippocampus

participates in personal memory and spatial navigation

cingulate cortex

invilved in sexual behavior, among other social interactions

neocortex

the heavily wrinkled outer part of the forebrain that contains six layers of cells (gray matter)

primary areas

receives projections from the major sensory systems or send motor projections to the muscles

secondary areas

adjacent to and interconnected with primary areas, and involved in elaborating information received from or sends commands to primary areas

tertiary areas (association cortex)

mediates complex activities such as language, planning, memory, and attention