The Nervous System 6 Lesson 6.1: Overview of the Nervous System Lesson 6.2: Transmission of Nerve Impulses Lesson 6.3: Functional Anatomy of the Central Nervous System Lesson 6.4: Functional Anatomy of the Peripheral Nervous System Lesson 6.5: Injuries and Disorders of the Nervous System

Overview of the Nervous System Chapter 6: The Nervous System Lesson 6.1 Overview of the Nervous System

Nervous System Overview organization of the nervous system two major divisions the efferent nerves nervous tissues neuroglia neurons

Organization of the Nervous System two major divisions central nervous system (CNS) peripheral nervous system (PNS) sensory receptors afferent (sensory) nerves efferent (motor) nerves

Two Major Divisions

The Efferent Nerves somatic nervous system autonomic nervous system voluntary autonomic nervous system involuntary sympathetic parasympathetic

Nervous Tissues neuroglia neurons also known as glial cells support the neurons protect the neurons neurons transmit nerve impulses

Neuroglia central nervous system astrocytes microglia ependymal oligodendrocytes

Neuroglia peripheral nervous system Schwann cells satellite cells

Neurons dendrites cell bodies axons send information to cell body send information away from cell body

Neuron Types by Function sensory neurons send impulses toward CNS motor neurons send impulses away from CNS interneurons bridges between neurons

Neuron Structures bipolar unipolar multipolar one axon and one dendrite unipolar one axon multipolar one axon and many dendrites

Review and Assessment Match these words with 1–4 below: sympathetic nervous system, myelin, synapse, axon. 1. high alert 2. transmits impulses away from cell body 3. fatty insulating material 4. gap between neurons

Transmission of Nerve Impulses Chapter 6: The Nervous System Lesson 6.2 Transmission of Nerve Impulses

Transmission of Nerve Impulses action potentials change in cell membrane charge impulse transmission charge change travels along axon reflexes involuntary response to stimulus

Action Potentials polarized depolarized repolarized refractory period

Impulse Transmission saltatory conduction transmission at synapses gap junctions neurotransmitter excitatory effect inhibitory effect

Reflexes somatic autonomic stimulate skeletal muscles stimulate involuntary muscles

Review and Assessment Fill in the blanks with: reflexes, saltatory conduction, neurotransmitter, or action potential. 1. A(n) _______________ is an all or none response. 2. _______________ occurs only in myelinated axons. 3. _______________ are rapid, involuntary responses. 4. The axon terminal has tiny vesicles filled with _______________.

Functional Anatomy of the Central Nervous System Chapter 6: The Nervous System Lesson 6.3 Functional Anatomy of the Central Nervous System

The Brain Cerebrum Diencephalon brain stem cerebellum meninges blood-brain barrier

Cerebrum Cerebrum Associated with sensory (interpret impulses) and motor functions (control muscular movement) Provides higher mental functions of memory and reasoning Seat of intelligence and personality Functions to control skeletal muscles, vision, hearing, taste, and skin sensations

Cerebrum cerebral cortex lobes primary motor cortex gyrus sulcus fissure lobes Frontal – Motor. Association areas- high intellectual processes. Parietal – Sensory. Association- speech, thoughts feelings. Occipital – Sensory- Vision. Association – Combine visual images with other senses Temporal – Sensory – Hearing and smelling. Assoc – visual senses, music, complex sensory primary motor cortex primary somatic sensory cortex

Cerebrum

Diencephalon Thalamus – Pain, touch, and temperature Hypothalamus – Controls and integrates autonomic NS Epithalamus – Connects limbic system to other parts of the brain

Brain Stem Midbrain – relay station for sensory and motor impulses Relays info over vision, hearing, motor activity, sleep/wake cycles, alertness, and temp regulation Pons – regulates breathing medulla oblongata – regulates heart rate, blood pressure, and breathing. Controls reflexes for coughing, sneezing, and vomiting.

Medulla Oblongata

Medulla Oblongata Medulla Oblongata – enlarged continuation of spinal cord All nerve fibers pass through Contains Cardiac center – increases/decreases heart rate Vasomotor center – stimulates smooth muscle in blood vessels to contract. Constriction heart rate increases. (vasoconstriction) Vasodilation Respiratory center – adjusts rate and depth of breathing Works with pons Reflex center – coughing, sneezing, swallowing, vomitting Injuries to the medulla oblongata are often fatal

The Brain Cerebellum – balance Meninges Blood-brain barrier dura mater Blood vessels supply nutrients Meninges dura mater arachnoid mater pia mater

Spinal Cord

Myths

Pain an unpleasant awareness of a noxious stimulus or bodily harm General info highly subjective to person experiencing it pain of some type is the most frequent reason for physician consultation in the US, causing half of all Americans to seek medical care annually pain that stops without treatment or responds to simple measures is called acute pain is part of the body’s defense system pain that becomes pathological rather than beneficial is called chronic

Pain Intensity Localization some have used a numeric scale ranging from 0-10 Localization usually named according to area or region of association(HEADACHE, BACKACHE) Radiating pain occurs when stimulus of a nerve at one site is perceived as pain in the sensory distribution of that nerve Sciatica– involves pain running down the back of the buttock, leg, and bottom of foot (it is caused by compression of the nerve root in the lumbar spine)

Pain Referred pain usually happens when sensory fibers from the viscera enter the same segment of the spinal cord as nerves from superficial tissue heart attack—pain in left arm Phantom pain is the sensation of pain from a limb or organ that has been lost or from which a person no longer receives signals

Review and Assessment True or False? 1. The gyri divide the brain into 4 regions. 2. The hypothalamus regulates blood pressure. 3. The meninges has 3 layers. 4. The cerebellum coordinates balance. 5. The pons is also called the interbrain.

Functional Anatomy of the Peripheral Nervous System Chapter 6: The Nervous System Lesson 6.4 Functional Anatomy of the Peripheral Nervous System

Functional Anatomy of the Peripheral Nervous System nerve structure cranial nerves spinal nerves and nerve plexuses autonomic nervous system

Nerve Structure endoneurium perineurium epineurium covers axons bundles fascicles epineurium wraps nerves

Cranial Nerves

Spinal Nerves and Nerve Plexuses 31 pairs dorsal root ventral root dorsal ramus – carry nerve impulses to muscle and skin of trunk ventral ramus – carry nerve impulses to muscle and skin of trunk Plexuses – complex interconnection of nerves formed by ventral rami

Autonomic Nervous System preganglionic and postganglionic neurons sympathetic nerves fight-or-flight action parasympathetic nerves resting or digesting action

Review and Assessment Match these words with 1–4 below: efferent, ganglion, optic, perineurium. 1. wraps fascicles 2. motor 3. a cranial nerve 4. enlarged junction

Injuries and Disorders of the Nervous System Chapter 6: The Nervous System Lesson 6.5 Injuries and Disorders of the Nervous System

Injuries to the Brain and Spinal Cord traumatic brain injury – occurs during violent impacts to the head cerebral palsy – group of nervous system disorders caused by dmg to the brain early on spinal cord injury – fractures or displacements of the vertebrae can result in injury to the spinal cord

Zika Virus

Traumatic Brain Injury violent impact to head Mild – may remain conscious or lose consciousness for a short bit. Symptoms: headache, confusion, dizziness, disrupted vision, ringing ears, bad taste in mouth, fatigue, abnormal sleep, behaviour changes, trouble with intellectual functions Moderate Same symptoms as above with worse/longer headache, repeated nausea/vomitting, seizures, slurred speech, weakness, numbness in extremities severe 50% require surgical repair

Cerebral Palsy damage to brain motor function impairment before birth during birth during infancy motor function impairment Caused by several conditions Brain infections Head injury Impaired liver function

Spinal Cord Injuries C1–C3: usually fatal C1–C4: quadriplegia – loss of function below neck C5–C7: paralysis of lower extremities T1–L5: paraplegia Loss of function in Trunk and legs Corepics/Shutterstock.com

Common Diseases and Disorders of the CNS Meningitis – inflammation of meninges surrounding brain and spinal cord multiple sclerosis – autoimmune disease that destroys myelin sheaths Epilepsy - group of brain disorders characterized by repeated seizures Parkinson’s disease Common amongst elderly tremors and difficulty moving Dementia and Alzheimer’s disease – loss of function in 2 or more areas of cognition

Review and Assessment Match these words with 1–4 below: quadriplegia, multiple sclerosis, dementia, cerebral palsy. 1. inflammation destroys myelin sheath 2. loss of memory and thinking 3. loss of function below the neck 4. may begin before birth

Brains