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Nursing Reference: Introduction to Nervous System Slide Transcript
Slide 1: NERVOUS SYSTEM Divisisons of Nervous System

Slide 2: WHAT ARE NERVE CELLS? • Neurons are similar to other cells in the body – S urrounded by cell membrane – Have a nucleus that contains genes – Contain cytoplasm, mitochondria and other organelles – Carry out basic cellular processes such as protein synthesis and A TP production • Neurons are different by – S pecialized extensions called dendrites and axons – Communicate with each other by electrochemical process – Contain some specialized structures (synapses) and chemicals (neurotransmitters)

Slide 3: Neurons • Most neurons consist of a cell body and extensions called dendrites and axons. • Cell B ody contains the nucleus • Dendrites carry impulses towards cell body • A xons carry impulses away from the cell body

Slide 4: Types of Neurons • Sensory neurons – Carry nerve impulses from a receptor to the CNS – Have long dendrites and short axons • Motor neurons – Carry nerve impulses from the CNS to an effector (ex. muscle or gland) – Have short dendrites and long axons • Interneurons – Found completely within the CNS – Provide a link within the CNS between sensory neurons and motor neurons – Have short dendrites and long or short axons

Slide 5: Reflex Arc • S implest nerve pathway • Occurs without brain coordination • F ive components – Receptor – S ensory neuron – Interneuron in spinal cord – Motor neuron – Effector

Slide 6: REFLEX ARC

Slide 8: Nerves • Consist of many fibers (neurons) wrapped in myelin • 3 Types of nerves – S ensory nerves contain only the long dendrites of sensory neurons wrapped in myelin • Carry impulses from a receptor to the CNS – Motor nerves contain only the long axons of motor neurons wrapped in myelin • Carry impulses from the CNS to an effector – Mixed nerves contain both the long dendrites of sensory neurons and the long axons of motor neurons wrapped in myelin • Conduct impulses to and from CNS

Slide 9: A ll nerves within the PNS contain a thin membrane called the neurilemma • Neurilemma promotes the regeneration of damaged axons • Grey M atter – Nerves in the brain and spinal cord (CNS )that lack myelin and neurilemma • White matter – Nerves in the brain and spinal cord (CNS ) that contain myelin and neurilemma

Slide 10: Ganglia • Groups of neuron cell bodies that lie within the PNS • Not included with nerves since nerves only contain axons and dendrites

Slide 11: Central Nervous System (CNS) • Contains the nerves of the brain and spinal cord – Function = coordinating center of incoming/outgoing information

Slide 12: • B rain is found in the skull & serves as overall control center for the nervous system • S pinal Cord is surrounded by vertebrae and extends down the back of the neck, thorax and abdomen – Center of many reflex actions – Provides a link between sensory and motor nerves • B oth are enclosed in 3 protective membranes called the meninge • S pace between meninge contains cerebrospinal fluid which protects and cushions the CNS

Slide 13: Spinal VS Epidural

Slide 14: Peripheral Nervous System (PNS) • A ll parts of the nervous system lying outside the brain and spinal cord. • The sensory and motor neurons that connect to the CNS – Function = to carry info between organs of the body and the CNS • Humans have – 12 paris of cranial nerves (sensory/motor/mixed) which control the head, face, neck, shoulders • Except V A GUS nerve – controls internal organs – 31 pairs of spinal nerves (mixed) which take impulses to and from the spinal cord

Slide 15: Cranial nerves

Slide 16: Spinal Nerves

Slide 17: Innervated Body Spinal Nerve(s) Symptom(s) of SCI Part(s) C1 Head and Neck Quadriplegia C2-C4 Diaphragm Breathing problem No control at wrist or C5 Deltoids, biceps hand C6 Wrist extenders No hand function dexterity problems with C7-T1 Triceps, hand hand and fingers Paraplegia, poor trunk T2-T8 Chest muscles control T9-T12 Abdominal muscles Paraplegia Decreasing control of Leg muscles, bowel, hip flexors and legs, Lumbar and Sacral bladder, sexual organs dysfunction of bowel, bladder, and sex Table 04 Symptom(s) of Spinal Cord Injury Note: Other effects of S CI may include low blood pressure, inability to regulate blood pressure effectively, reduced control of body temperature, inability to sweat below the level of injury, and chronic pain.

Slide 19: PNS Somatic & Autonomic Nerves • S omatic nerves control skeletal muscle, bones, skin that a person can control – S ensory neurons which relay info about environment to CNS Reflex Arc – Motor neurons which initiate appropriate response • A utonomic nerves control the muscles of the glands and internal organs which we can’t control – S ympathetic & parasympathetic components

Slide 20: “FLIGHT OR FIGHT RESPONSE” S ympathetic component prepares body for stress [neurotransmitter used=norepinephrine] • Diverts blood from internal organs to skeletal muscles, heart & brain Parasympathetic brings things back to normal [neurotransmitter used=acetylcholine] • Work in conjunction/opposition to each other – Ex. “ on” /“ off” switches

Slide 23: You come across a bear on your walk to school…what happens? • S ympathetic nervous system does what? • Increases heart rate • Increases breathing rate • Dilates bronchioles • Dilates pupils • Inhibits digestion

Slide 24: ADRENALIN (epinephrine) • S ympathetic nervous system also stimulates secretion of epinephrine and nor-epinephrine from the medulla of the adrenal glands • Prepares body for “ flight or fight” response • “ E pi-pen” given in allergic reactions as it relaxes constricted airways

Slide 25: PL O RE CA P S tudents will be able to: • Identify and give functions for each of the following: dendrite, cell body, axon • Distinguish among sensory, motor and interneuron with respect to structure and function • Contrast the locations and functions of the central and peripheral nervous systems • Differentiate between the functions of the sympathetivd and parasympathetic divisions fo the autonomic nervous system • Identify the source gland for adrenalin and explain its role in the “ fight or flight response





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