t=1224331639_7247750-Medical-Surgical-Nursing-by-Banny -...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: MEDICAL-SURGICAL NURSING By: Anthony T. Villegas R.N. Overview of structures and functions: NERVOUS SYSTEM • The functional unit of the nervous system is the nerve cells or neurons • The nervous system is composed of the ff: Central Nervous System • Brain • Spinal Cord – serves as a connecting link between the brain & the periphery. Peripheral Nervous System • Cranial Nerves –12 pairs; carry impulses to & from the brain. • Spinal Nerves – 31 pairs; carry impulses to & from spinal cord. Autonomic Nervous System subdivision of the PNS that automatically controls body function such as breathing & heart beat. Special senses of vision and hearing are also covered in this section • Sympathetic nervous system – generally accelerate some body functions in response to stress. • Parasympathetic nervous system – controls normal body functioning. CELLS A. NEURONS • Primary component of nervous system • Composed of cell body (gray matter) , axon, and dendrites • Basic cells for nerve impulse and conduction. Axon • Elongated process or fiber extending from the cell body • Transmits impulses (messages) away from the cell body to dendrites or directly to the cell bodies of other neurons • Neurons usually has only one axon Dendrites • Short, blanching fibers that receives impulses and conducts them toward the nerve cell body. • Neurons may have many dendrites. Synapse • Junction between neurons where an impulse is transmitted Neurotransmitter • Chemical agent (ex. Acetylcholine, norepinephrine) involved in the transmission of impulse across synapse. Myelin Sheath • A wrapping of myelin (whitish, fatty material) that protects and insulates nerve fibers and enhances the speed of impulse conduction. o Both axons and dendrites may or may not have a myelin sheath (myelinated/unmyelinated) o Most axons leaving the CNS are heavily myelinated by schwann cells Functional Classification 1. Afferent (sensory) neurons • Transmit impulses from peripheral receptors to the CNS 2. Efferent (motor) neurons • Conduct impulses from CNS to muscle and glands 3. Internuncial neurons (interneurons) • Connecting links between afferent and efferent neurons Properties 1. Excitability – ability of neuron to be affected by changes in external environment. 2. Conductility – ability of neuron to transmit a wave of excitetation from one cell to another. 3. Permanent Cell – once destroyed not capable of regeneration. TYPES OF CELLS BASED ON REGENERATIVE CAPACITY 1. Labile • Capable of regeneration. • Epidermal cells, GIT cells, GUT cells, cells of lungs. 2. Stable • Capable of regeneration with limited time, survival period. • Kidney cells, Liver cells, Salivary cells, pancreas....
View Full Document

This note was uploaded on 02/10/2010 for the course ADN 105 taught by Professor Aaa during the Spring '07 term at 東京大学.

Page1 / 107

t=1224331639_7247750-Medical-Surgical-Nursing-by-Banny -...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online