Central Nervous System

Divisions of the Brain Brainstem

Medulla oblongata extension of spinal cord Contains the cardiac, respiratory and vasomotor

centers (control heartbeat, blood vessel diameter) Consists of white and gray matter intermingled

Pons Midbrain

Diencephalon Small, located above midbrain, below cerebrum Consists of 2 major structures: hypothalmus and

thalmus Hypothamus:

Pituitary gland is an extension of hypothalmus Major control over most major organs Make hormones secreted by pituitary gland Secrete releasing hormones into blood to the anterior

pituitary gland Helps regulate water balance, body temperature, sleep

cycles and appetite and many emotions

Diencephalon Thalmus

Dumb bell shaped gray matter, above hypothalmus

Axons go into cerebellum Helps produce sensations, associates

sensations with emotions and plays a role in the arousal or alerting mechanism

Cerebellum Second largest part of human brain Arbor vitae – tree of life, gray matter on

outside, white matter inside Produce smooth, coordinated movements,

maintain equilibrium and sustain normal postures.

cerebrum Largest and upper most part of brain Ridges – convolutions or gyri Grooves – sulci, deep grooves – fissures

Longitudinal fissure – divides into left and right

Find also the central sulcus, lateral fissure Corpus callosum – connects left and

right hemisphere of the brain

cerebrum 4 major lobes of the brain named for

bones Frontal, Occipital, Temporal, parietal

Cerebral cortex – gray matter, surface of cerebrum White matter (tracts) makes up most of

cerebrum exception is basal ganglia (produce automatic

movements and posture, ex. Parkinson disease

Brain disorders Cerebrovascular accident (CVA) – stroke –

hemorrhage or cessation of blood flow through vessels in brain, neurons die If damage occurs in a motor control section of brain,

movement ceases Cerebral palsy – damage to brain tissue

Prenatal infections, trauma to the head before, during, after birth, reduced oxygen to brain

Spastic paralysis – involuntary contractions of affected muscles

Hemiplegia – 1 side of body Paraplegia – both legs Triplegia – both legs, 1 arm Quadriplegia – all 4 appendages

Degenerative brain disorders Destruction of neurons in the brain Affects memory, attention span,

intellectual capacity, personality and motor control = dementia

Alzheimer Disease (AD) – lesions on cerebral cortex

Huntington disease (HD) – chorea – involutary purposeless movements

Seizure Seizure – sudden bursts of abnormal

neuron activity Range from mild to severe

Epilepsy – recurring or chronic seizures Can be caused by tumors, trauma, or chemical

imbalances, most idiopathic Medications block neurotransmitters in

affected areas of the brain.

Spinal cord Average of 17 – 18 inches From occipital bone to L1 vertebrae core is made up of gray matter Outer part is white matter – spinal tracts

Spinal cord 2 way conduction

Ascending tracts – to brain Descending tracts – from the brain

Primary reflex center Cut in the spinal cord results in no

communication Anesthesia – loss of sensation Paralysis – loss of the ability to make

voluntary movements

Coverings Meninges – touch, fluid-containing

membrane 3 layers

Dura mater – tough outer layer Pia mater – innermost membrane, covers

spinal cord Arachnoid mater – between dura and pia

mater, cob web like Meningitis – infection or inflammation of

meninges

Fluids Cerebrospinal fluid (CSF) – fills

subarachnoid spaces in brain and spinal cord and ventricles in brain 2 lateral ventricles and third ventricle

CSF is continuously begin made from fluid filtering out of choroid plexus and into ventricles and continues to circulate around the brain and spinal cord

Hydrocephalus – water on the brain – accumulation of CSF in ventricles