Central Nervous System Organization & Function

Central Nervous System

brain + spinal cord

- integrating center

- inter & projecting neurons

Peripheral Nervous System

afferent + efferent

- neurons

Afferent

PNS: info in

- somatic sensory

- visceral sensory

- special sensory

Efferent

PNS: output

- somatic motor

- autonomic motor

(sympathetic, parasympathetic, enteric)

Afferent Neurons

project into CNS

Efferent Neurons

project out of CNS

Nuclei

groups of neuron cell bodies in CNS

Ganglia

groups of neuron cell bodies in PNS

Tracts

groups/bundles of axons in CNS

Nerves

groups/bundles of axons in PNS

Spinal cord gray matter

nuclei

Spinal cord white matter

tracts / fibers / columns

Brain gray matter

cortical layers, nuclei

Brain white matter

tracts / fibers

Protective elements

- meninges

- cerebrospinal fluid

- blood-brain barrier

Meninges

3 layers between bone & CNS tissue

- protect soft tissue

Meninges layers

1. dura mater

2. arachnoid membrane

3. pia mater

Dura matter

closest to bone skull

Arachnoid mater

along brain

Pia mater

closest to brain

- sticky

- blood vessels

Cerebrospinal fluid (CSF) functions

- provides buoyancy

- circulate nutrients

- removes waste

- buffers temp

Ventricular system (CSF)

mechanical protection

- 2 lateral ventricles

- third ventricle

- cerebral aqueduct

- fourth ventricle

Blood-brain barrier

- capillaries

- endothelial cells

- astrocyte

- tight junction

Astrocyte

type of glial cell for protection

- support tight junction (more restrictive)

- avoid leakage

(can be hard to get medicine across BBB)

Sulci

grooves/depressions in cortex

Gyri

folds/ridges in cortex

Cerebral cortex

- sensory area

- motor areas

- association areas

Sensory area

cerebral cortex

- perception

Motor areas

cerebral cortex

- skeletal muscle movement

cerebral cortex

- skeletal & muscle movement

Association areas

integrate info & direction of voluntary movement

Basal ganglia

movement

Limbic system

- amygdala (emotion, memory)

- hippocampus (learning, memory)

Functions of cerebrum (CNS)

- cerebral cortex

- basal ganglia

- limbic system

Functions of cerebellum (CNS)

movement coordination

Functions of diencephalon (CNS)

- thalamus

- pineal gland

- hypothalamus

- pituitary gland

Thalmus

diencephalon

- integrating center

- relay station for sensory & motor info

Pineal gland

diencephalon

- melatonin secretion

Hypothalamus

diencephalon

- homeostasis

- behavior drives (emotions)

- autonomic functions

Pituitary gland

diencephalon

- hormone secretion

Brain stem function (1)

pathway of tracts between cerebral cortex & spinal cord

Brain stem function (2)

site of origin of nuclei of cranial nerves

(3rd to 12th)

Brain stem function (3)

Site of emergence of cranial nerves

(3rd to 12th)

Brain stem function (4)

Contains groups of nuclei & related fibers known as reticular formation

Reticular formation (brainstem)

- control level of consciousness

- perception of pain

- regulation of cardiovascular & respiratory systems

Brain stem strucuture

- diencephalon (thalamus, hypothalamus)

- midbrain

- pons

- medulla oblongata

Midbrain

brain stem

- process visual & auditory data

- generation of reflexive somatic motor responses

- maintenance of consciousness

Pons

brain stem

- relays sensory info to cerebellum & thalamus

- subconscious somatic & visceral motor centers

Medulla oblongata

brain stem

- relay sensory info to thalamus & other parts of brain stem

- autonomic centers for reg of visceral function

Visceral function (brain stem)

cardiovascular, respiratory, digestive system activities

Cerebellum function (CNS)

- coordination of movement (reflex & voluntary)

- plan & generate movement

- motor learning

- maintain balance & equilibrium

Cerebellum function examples

- athletics

- playing musical instruments

- speaking

- writing

Signs of cerebellar pathology

- ataxia (tremor, deficits in gait, speech, swallowing, eye movement)

- difficulties walking & balance

- dizziness

Diencephalon thalamus (CNS)

- pathway for all sensory info to cerebral cortex (except smell)

- important for directing attention

- provides feedback for controlling movement

Diencephalon hypothalamus (CNS)

major endocrine gland / integrating center

- regulates homeostasis

- links endocrine & nervous systems

- affects behaviors (hunger, satiety, thirst)

- thermoregulation

- communicates with autonomic

Functional divisions of the cortex

- sensory areas

- motor areas

- association areas

Sensory areas

sensory input translated into perception

- awareness

Motor areas

direct skeletal muscle movement

Association areas

integrate information from sensory & motor areas

- can direct involuntary behaviors

Cerebral cortex (CNS)

outermost layer of cerebrum

- cognitive & behavioral networks

Examples of integrated functions

- voluntary motor control

- language

- sleep

- emotions & motivation

- learning & memory

Integrated function

- association cortex

- limbic system

- learning & memory

Limbic system functions

- learning

- emotion

- appetite

- sex drive

- endocrine integration

Hippocampus

limbic system

- involved in learning & memory

Amygdala

limbic system

- involved in emotion & memory

Memory

retention of info, skills, or thoughts

Short-term

aka working memory

- lasts seconds to minutes

- may be consolidated into long-term memory

Long-term

- procedural (learning motor skills & behaviors)

- declarative (learned experiences, facts, events)

Posterior hippocampus

structural plasticity & adaptation

- spatial navigation

Reflex

automatic response to stimulus that does not require brain