NERVOUS SYSTEM

The central nervous system (CNS) comprises the

brain and spinal cord.

The peripheral nervous system (PNS) consists of

all the nerves and ganglia outside the brain and spinal cord

Stimuli

changes inside and outside the body

Integration

processes and interprets the sensory input

Effectors

muscles and glands

Sensory division (afferent)

Conducts action potentials from sensory receptors to the CNS.

Motor division (efferent)

Conducts action potentials to effector organs, such as muscles and glands.

Somatic nervous system

Transmits action potentials from the CNS to skeletal muscles

Autonomic nervous system

Transmits action potentials from the CNS to cardiac muscle, smooth muscle, and glands

The involuntary branch of the nervous system

ANS

Divided into two divisions

Sympathetic division and Parasympathetic division

Sympathetic

"fight or-flight"

Parasympathetic

housekeeping activities

Enteric neurons

can monitor and control the digestive tract independently of the CNS through local reflexes

Neurons

receive stimuli, conduct action potentials, and transmit signals to other neurons or effector organs.

Glial cells

supportive cells of the CNS and PNS. carry out different functions that enhance neuron function and maintain normal conditions within nervous tissue

Schwann cells

provide myelin to axons of neurons in the PNS.

Nodes of Ranvier

gaps in myelin sheath along the axon

Sensory (afferent) neurons

Carry impulses from the sensory receptors

Motor (efferent) neurons

Carry impulses from the central nervous system

Interneurons (association neurons)

Connect sensory and motor neurons

Multipolar neurons

many dendrites and a single axon from the cell body

Bipolar neurons

one axon and one dendrite

Unipolar neurons

have a short single process leaving the cell body

Astrocytes

Abundant, star-shaped cells

Astrocytes function

serve as the major supporting cells in the CNS.

Astrocystes Form barrier between

capillaries and neurons

Microglia (CNS)

Spider-like phagocytes

Microglia function

Dispose of debris

Ependymal cells (CNS)

Line cavities of the brain and spinal cord

Ependymal cells (CNS) Circulate

cerebrospinal fluid

Oligodendrocytes (CNS)

Produce myelin sheath around nerve fibers in the central nervous system

Satellite Cells

Protect neuron cell bodies.

Schwann Cells

Form myelin sheath in the peripheral nervous system

Myelin sheaths are

specialized layers that wrap around the axons of some neurons

Myelin sheaths are formed by

oligodendrocytes in the CNS and Schwann cells in the PNS

Unmyelinated Neurons

Unmyelinated axons lack the myelin sheaths.

Gray matter

neuron cell bodies and their dendrites, very little myelin.

White matter

parallel axons with their whitish myelin sheaths.

4 major regions of the brain

brainstem, cerebellum, diencephalon, cerebrum

Brainstem

Attaches to the spinal cord

Midbrain

Mostly composed of tracts of nerve fibers. Reflex centers for vision and hearing

Pons

The bulging center part of the brain stem. Includes nuclei involved in the control of breathing.

Medulla oblongata

The lowest part of the brain stem. Contains important control centers: Heart rate control; Blood pressure regulation; Breathing; Swallowing.

Reticular Formation

scattered throughout brainstem.

Reticular activating system (RAS)

awake/sleep cycle

Parts of the brain stem

Midbrain, Pons, Medulla oblongata

Cerebellum

Large, cauliflower-like structure

Cerebellum Located

under the occipital lobe of the cerebrum

Cerebellum Processes information from

cerebral motor cortex, proprioceptors, and visual and equilibrium pathways

Cerebellum Outer and Inner

Outer cortex is made up of gray matter and an inner region of white matter.

Cerebellum

Provides "instructions" to cerebral motor cortex and subcortical motor centers, resulting in smooth, coordinated skeletal muscle movements and is Responsible for proper balance and posture

Diencephalon Located between the

brainstem and cerebrum

Components

Thalamus, Hypothalamus, Epithalamus

Thalamus

largest portion of diencephalon. The relay station for sensory impulses. Transfers impulses to the correct part of the cortex for localization and interpretation.

Hypothalamus

below thalamus. Important nervous system center.

Epithalamus

houses the pineal body (an endocrine gland).

Epithalamus includes the

choroid plexus

choroid plexus

forms cerebrospinal fluid

Cerebrum Largest portion of

brain

Divisions of cerebrum

Right hemisphere and Left hemisphere (separated by longitudinal fissure)

Longitudinal fissure

divides cerebrum into left and right hemispheres

Gyri

folds on cerebral cortex that increase surface area

Sulci

shallow indentations

Fissure

deep indentations

Cerebral Cortex

surface of cerebrum, composed of gray matter. controls thinking, communicating. remembering, understanding, and initiates voluntary movements.

Lobes of the Cerebrum

frontal, parietal, temporal, occipital

Frontal lobe Location

anterior

Frontal lobe Function

controls voluntary motor functions, aggression, moods, smell

Parietal lobe Location

top of the brain

Parietal lobe Function

process information about our sense of touch

Occipital lobe Location

posterior

Occipital lobe Function

vision

Temporal lobe Location

lateral

Temporal lobe Function

hearing, smell, memory

Primary sensory areas

where sensations are perceived

Primary somatosensory cortex

general sensory area; in parietal lobe; sensory input such as pain, pressure, temp.

Sensory speech (Wernicke's area)

parietal lobe; where words are heard and comprehended

Primary motor cortex

frontal lobe; control voluntary motor movement

Premotor area

frontal lobe; where motor functions are organized before initiation

Prefrontal area

motivation and foresight to plan and initiate movement

Motor speech (Broca's area)

frontal lobe; where words are formulated

Layers of the Cerebrum Gray matter

outer layer; composed mostly of neuron cell bodies

Layers of the Cerebrum White matter

fiber tracts inside the gray matter; ex. Corpus callosum connects hemispheres.

Layers of the Cerebrum Basal nuclei

internal islands of gray matter. Regulates voluntary motor activities by modifying info sent to the motor cortex. Involved in Huntington's and Parkinson's Diseases.

Brain Waves and Consciousness

Used to diagnose and determine treatment for brain disorders

Electroencephalogram (EEG)

Electrodes are placed on scalp to record brain's electrical activity

Alpha waves

person is awake in quiet state

Beta waves

intense mental activity

Delta waves

deep sleep

Theta waves

in children

Working memory occurs when

the brain briefly stores information required for the immediate performance of a task. It lasts only a few seconds to minutes

Short-term memory lasts longer than

working memory and can be retained for a few minutes to a few days.

Short-term memory is transferred to

long-term memory, where it may be stored for only a few minutes or become permanent, by consolidation.

Declarative memory, or explicit memory

involves the retention of facts, such as names, dates, places, and related emotional undertones.

Procedural memory, or reflexive memory

involves the development of motor skills, such as riding a bicycle

The space between the dura mater and the arachnoid mater is the

subdural space

The CNS contains fluid-filled cavities

ventricles

Each cerebral hemisphere contains a relatively large cavity called the

lateral ventricle.

The third ventricle is a

smaller, midline cavity located in the center of the diencephalon between the two halves of the thalamus and connected by foramina (holes) to the lateral ventricles.