The Nervous System: Structure and Function

Central Nervous System

located within the skull and spine

Peripheral Nervous System

outside the skull and spine

Somatic Nervous System

-division of the PNS

-interacts with environment

-efferent and afferent nerves

Autonomic Nervous System

-division of the PNS

-regulates body's internal environment

-two types of efferent nerves (sympathetic and parasympathetic)

Sympathetic Nerves

-ANS efferent nerve

-Stimulate, organize, mobilize energy

-Arousal

-Synapse far from target organ

-Project from CNS in lumber and thoratic region of spinal cord

-two stage neural path

Parasympathetic

-ANS efferent nerve

-conserve energy, relaxation

-synapse close to target

-project from brain and sacral

-two stage neural path

Three Important Principles of Para and Sym Nerves

1.) Para = conserve energy

Sym = stimulate/use

energy

2.) Target organs get input from both types to regulate functioning

3.) Para = relaxation

Sym = arousal

Cranial Nerves

12 pairs of nerves that extending from the brain instead of the spine like the rest of PNS efferent nerves

Vagus Nerves

longest cranial nerves and contain both motor and sensory nerves traveling two and from the gut

Afferent Nerve

carry sensory info from sensory organs to the CNS

Efferent Nerves

care motor signals from CNS to skeletal muscles

Anterior

Head: towards the face

Body: towards head

(contrast = posterior)

Posterior

Head: back of head

Body: towards the booty

(contrast = anterior)

Dorsal

Head: top of skull

Body: towards the back

(contrast = ventral)

Ventral

Head: towards brain stem

Body: towards chest

(contrast = dorsal)

lateral

From the center of the body out

Medial

Going towards the midline of the body

Ipsilateral

belonging to or occurring on the same side of the body

Contralateral

On the opposite side of the body

Spinal Cord Structure

Composed of two diff areas:

1.) inner H shaped core of gray matter

2.) surrounding area of white matter

Gray Matter

composed largely of cell bodies and unmyelinated interneurons

White Matter

composed largely of myelinated axons

Meninges

3 protective membranes that encase brain and spinal cord (dura mater, archnoid, pia mater)

Dura Mater

outer most, tough membrane of meninges

tough mother

Arachnoid

fine, spider like membrane in the meninges that follows the dura mater

Superarachnoid Space

space under arachoid containing large blood vessels and cerebrospinal fluid

Pia Mater

delicate membrane that adheres to surface of CNS and innermost layer of meninges

pious mother

Cerebrospinal Fluid

protects brain and spinal cord

fills central canal and cerebral ventricles of the brain

Ventricles

four large chambers in the brain

5 Major Brain Divisions

1.) Telencephalon

2.) Diencephalon

3.) Mesencephalone

4.) Metencephalon

5.) Myelencephalon

*T on top and the rest in alphabetical order

Myelencephalone or Medulla (hindbrain)

Most posterior of brain regions

Composed of:

-Large tracts carrying signals bw rest of brain

-Reticular Formation

-Role in sleep, arousal, attention, movement, muscle tone, reflexes

Reticular Formation

-complex network of approx. 100 tiny nuclei that occupy central core of brain stem from posterior of myelencephalon to anterior of midbrain

-role in arousal, sleep, attention, movement, maintenance of muscle tone, and various reflexes

Metencephalon (hindbrain)

Composed of:

-ascending/descending tracts

-Pons

-Cerebellum

-helps regulate breathing, heart and blood vessel function, digestion, sneezing, and swallowing.

-center for respiration and circulation.

Pons

-anterior bulge of metencephalon

- communications and coordination center between the two hemispheres of the brain

-helps in the transferring of messages between various parts of the brain and the spinal cord

Cerebellum

-posterior bigger bulge and its important to sensorimotor functions

-damage = loss precise movements, adapting to changing conditions, cognitive deficits, use of language

Mesencephalon (midbrain)

two major divisions:

-tectum

-tegmentum

Tectum (roof)

dorsal surface roof of midbrain

audio and visual-motor functions

composed of two bumps

-inferior colliculi

-superior colliculi

Tegmentum

ventral to tectum

contains reticular formation, tracts, periaqueductal gray, substantia nigra, red nucleus

Diencephalon (forebrain)

Thalamus

Hypothalamus

Thalamus

large, two lobed structure in brain stem

lobes joined by massa intermedia

white lamina of myelinated axons cover surface

Hypothalamus

just below thalamus

major role in regulation of motivation behaviors (eat, sleep, sex)

Telencepholon (forebrain)

largest brain division

mediates most complex functioning (voluntary movement, sensory input, learning, speaking, problem solving)

crebral cortex

diff lobes

Cerebral Cortex

layer of tissue that covers cerebral hemisphere

gray matter

deepy convoluted (furrowed)

Corpus Callosum

largest cerebral commissure (tract that directly connects cerebral hemispheres)

Longitudinal Fissure

separation of cerebral hemispheres

Frontal Lobe

primary motor cortex

planning, executive functioning, language/grammar, working memory

Parietal Lobe

somatosensory cortex

space/body awareness, math, reading/writing

Postcentral Gyrus

analyzes sensations from the body

Temporal Lobe

auditory cortex

object recognition, face recognition, audio processing, word processing

Occipital Lobe

visual cortex

Limbic System

circuit of midline structures that circle the thalamus

regulation of motivation (fleeing, feeding, fighting, ****ing)