Functions Of The Nervous System

Submitted By Sequoia2007
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Pages: 20


The Nervous System
Controls and integrates sensory, motor and autonomic functions
Maintains internal homeostasis
Enables connection and response to external environment

Divisions of the Nervous System
Central Nervous System (CNS)
Peripheral Nervous System (PNS)

The Brain
Control Center of the nervous system
About 1400 grams/3 lbs
Protected by the skull
3 protective membranes (Meninges)
Dura Mater – Outter Layer
Arachnoid – Middle Layer
Pia Mater – Inner Layer
Epidural Space – Where arterial blood vessels are located between the skull and dura mater
Subarchnoid Space – Cerebrospinal Fluid (CSF) are located between the arachnoid and the pia mater

Regions of the Brain
Largest region of the brain
2 Hemispheres; Left & Right
Corpus Collosum – Thick band of nerve fibers that connects the 2 hemispheres
Fissures – Deep grooves, separate the hemispheres and separate the cerebrum from the cerebellum
Contra-Lateral Concept – Each hemisphere receives sensory and motor impulses from the opposite side of the body

Left Hemisphere
Right Hemisphere
Visual-Spatial Information (Art/Music)
Surrounding Physical Environment (Faces/Patterns)

Cerebral Cortex – The outer layer contains the gray matter which is made up of neurons
The rest of the cerebrum is made up of myelinated nerve fibers called whiter matter.

Hemisphere has 4 lobes
Frontal – Conscious thoughts, intelligence, predict future and its benefits
Parietal – Touch, Taste, Temp
Occipital – Analyzes sensory info about vision
Temporal – Analyzes sensory info about hearing/smell

Thalamus – Relay center receiving sensory information (5 Senses) to midbrains and cerebrum. Deals with emotions
Hypothalamus – Regulates body temp, heart rate, respiratory rate and BP, sensations of hunger and thirst, circadian rhythm, emotions an sex drive.

Brain Stem
Consists of the midbrain, pons and medulla oblongata
Medulla Oblongata – Respiratory center and regulates heart rate, BP, couching swallowing and vomiting. It is located at the base of the brain stem
Midbrain – the center for auditory and visual reflexes
Pons – Controls respiration

It is responsible for balance, posture and locomotion

*Broca’s area promotes speaking ability; Wernicke’s area promotes understanding of the spoken and written word.

Cerebrospinal Fluid (CSF)
Makes/Circulates by the ventricles of the brain
Circulates with in the subarachnoid space and spinal cord
Clear, colorless liquid protect the brain and spinal cord
125-150 mL produced daily – HIGH glucose, very FEW WBC and NO RBC

Blood Supply of the Brain
Receives 750 mL/Min
Uses 20% of body’s cardiac output
Circles of Willis – This circle protects the brain by providing alternative blood flow routes when an artery is blocked
The brain cannot store oxygen or glucose so it needs a constant supply
2 arterial systems supply blood to the brain
Internal Carotid Arteries
Vertebral Arteries

Blood-Brain Barrier
Composed of astrocytes that are joined by tight junctions
Decreased permeability so that harmful substances in the blood cannot enter the brain
Substance such as urea, some toxins and most antibiotics cannot pass this barrier

The Spinal Cord
Surround and protected by the vertebral column
The column consists of 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 4 fused coccyx
The inside of the spinal cord is H shaped and consists of gray matter surrounded by white matter
The gray matter contains 3 specialized areas called horns:
Ventral Horn - Motor Neurons
Dorsal Horn – Sensory Neurons
Lateral Horn – Sympathetic Neurons
The white matter forms ascending and descending pathways known as spinal tracts

The Peripheral Nervous System
Links the CNS with the rest of the body
Receives and conducts information from the external environment and transmits signals to muscles and organs of the body
Consists of:
Spinal Nerves
Cranial Nerves
The PNS is divided into the somatic