Chapter 6 The Nervous System Our nervous system has the ability to simultaneously direct multiple functions taking place in in our bodies Two major divisions Central nervous system CNS It directs the activity of the entire nervous system ID: 778794
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Slide1
Slide2Lesson 6.1
Overview of the Nervous System
Chapter 6: The Nervous System
Slide3Our nervous system has the ability to simultaneously direct multiple functions taking place in in our bodies.Two major divisions:
Central nervous system (CNS). It directs the activity of the entire nervous system.Brain Spinal
cord
Organization of the Nervous System
Slide4Peripheral nervous system (PNS).Sensory receptors: respond to stimuli such as pain
Afferent (sensory) nerves: transmit impulses from the sensory receptors in the skin, muscles & joints.Efferent (motor) nerves
: carry impulses from the CNS to the muscles and glands
Slide5Human Brain
Slide6Slide7Sheep Brain
Slide8Spinal Cord w/Brain
Slide9Two Major Divisions
Slide10There are two functional subdivisions of the efferent, or motor, nerves:Somatic nervous system (voluntary)
Stimulates our skeletal muscles, causing them to develop tension.Autonomic nervous system (involuntary)Controls the cardiac muscle of the heart and the smooth muscles of the internal organs.Sympathetic
Parasympathetic
The Efferent Nerves
Slide11Two categories of tissues exist within the nervous system: Neuroglia (
glial cells)These are specialized cells that perform support functions within the CNS.Astrocytes
Link the nutrient-supplying capillaries to neurons and control the chemical environment to protect the neurons from any harmful substances in the blood
.
Nervous Tissues
Slide12Microglia
Absorb and dispose of dead cells and bacteriaEpendymal cellsForm a protective covering around the spinal cord and central cavities within the brain.
Oligodendrocytes
Wrap around nerve fibers and produce a fatty insulating material called myelin.
Nervous Tissues
Slide13Slide14Peripheral nervous systemSchwann cells
Form the fatty myelin sheaths around nerve fibers in the PNS.Satellite cellsServe as cushioning support cells.
Neuroglia
Slide15Transmit nerve impulses throughout the bodyDendrites Send information (stimuli) to cell body.
Cell bodiesIncludes a nucleus and mitochondria, like all cell bodies.Axons Send information (impulses) away from cell body.
Neurons
Slide16Slide17Within the PNS, the Schwann cells wrap around the axon, covering most of it with a fatty myelin sheath.
The myelin sheaths insulate the axon fibers, which increases the rate of impulse transmission
.
The myelin sheaths are white
, giving rise to the term
white matter
to describe tracts of
myelinated fibers within the CNS
.
Gray matter
is the term for
unmyelinated nerve fibers
.
Neurons
Slide18Slide19Axon terminals are filled with tiny sacs (vesicles) that contain chemical messengers called
neurotransmitters.Axon terminals are separated from other neurons or muscle by a microscopic gap called the synaptic cleft
https://www.youtube.com/watch?v=DLN1UsvmVvM
Slide20Slide21Sensory (afferent) neurons
Send impulses from the skin and other organs toward CNSMotor (efferent) neuronsSend impulses away from CNS, to the muscles and glands directing body actions.
Interneurons (
association neurons
)
Form bridges between neurons
Neuron Types by Function
Slide22Slide23Slide24Bipolar
one axon and one dendriteNeuron Structures
Multipolar
one axon and many dendrites
Unipolar
one axon
Slide25Match 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 material4. Gap between neurons
Review and Assessment
Sympathetic Nervous system
Axon
Myelin
Synapse
Slide26Lesson 6.2
Transmission of Nerve Impulses
Chapter 6: The Nervous System
Slide27A nerve impulse is a tiny electrical charge (action potential) that transmits information between neurons.Occurs due to a change in cell membrane charge distribution along the axon
.https://www.youtube.com/watch?v=fHRC8SlLcH0Transmission of Nerve Impulses
Slide28Impulse transmissionIs the movement of charge change along axon membrane.The presence or absence of a myelin sheath and the diameter of the axon impact on the speed of the nerve impulse.
Since myelin sheath is an electrical insulator, action potentials “jump over” the myelinated regions of the axon increasing speed of the impulse
Transmission of Nerve Impulses
Slide29Impulse speed is also much faster in axons with a larger diameterImpulses that signal limb position to the brain travel extremely fast, up to 119 m/sthe sensation of pain moves more slowly, at less than 1 m/s.
Slide30Transmission at synapses
Gap junctionsNeurotransmitter Excitatory effectAcetylcholine, a chemical that activates muscle fibers
Inhibitory effect
Endorphins, inhibit nerve cells from
discharging more pain signals
Impulse Transmission at Axon Terminal
Slide31Reflexes are simple, rapid, involuntary, programmed responses to stimuliSomatic reflexesStimulate skeletal muscles
Autonomic reflexes Stimulate involuntary musclesReflexes
Slide32This is a direct route from a sensory receptor to an effector bypassing the brain
There are five components:Sensory receptorAfferent neuronInterneuron (in spinal cord)
Efferent neuron
Effector (muscle / gland)
Reflex Arc
Slide33https://www.youtube.com/watch?v=fHRC8SlLcH0
Transmission of Nerve Impulses
Slide34Fill in the blanks with: reflexes, or neurotransmitter.
1. _______________ are rapid, involuntary responses.2. The axon terminal has tiny vesicles filled with _______________.
Review and Assessment
Reflexes
neurotransmitter
Slide35Lesson 6.3
Functional Anatomy of the Central Nervous System
Chapter 6: The Nervous System
TURN IN YOUR COLORING SHEET!!!
Slide36The adult human brain weighs between 2¼ and 3¼ pounds and contains approximately 100 billion neurons and even more glial cells.The four major anatomic regions of the brain
areCerebrum Diencephalon brain stem
Cerebellum
Protective layers include:Meninges
Blood-brain barrier
The Brain
Slide37This is the left and right cerebral hemispheres. They make up the largest portion of the brain.
Cerebral cortex (outer surface) is composed of:Nonmyelinated gray matter.Internal tissue is
myelinated
white matter.
Cerebrum
Slide38Slide39Slide40The surface of the brain is not smoothGyrus: raised are of the curves
Sulcus: grooves between the gyriFissure: uniformly positioned deep grooves
Slide41Cerebrum
Slide42The sulci divide the brain into four regions called lobes: Frontal lobe
Problem solving, motor function, memory, judgment, impulse control etcParietal lobeCognition / integrating sensory information (visual)
Occipital
Vision Temporal
Speech, hearing, vision, memory
& emotion.
Cerebrum
Slide43The Story of Phineas Gage
Slide44Primary motor cortexSends
neural impulses to the skeletal muscles to initiate and control the development of muscle tension and movement of our body parts.
Primary somatic
sensory cortex
Interprets sensory impulses
received from the skin, internal organs, muscles, and joints.
Cerebrum
Slide45Also known as the, interbrain, is located deep inside the brain,
enclosed by the cerebral hemispheres. It includes:Thalamus Serves as a relay station for communicating information
between the body and the cerebral cortex.
Also maintains states of alertness
.
Diencephalon
Slide46Hypothalamus Key part of autonomic nervous system, regulating:
metabolism, heart rate, blood pressure, thirst
etc.
Epithalamus
Includes the
pineal gland
and
regulates
the
sleep-cycle hormones
that it secretes
Slide47Approximately the size of a thumb. It includes three structures:
Midbrain Superior end of the brain stem.Serves as a relay station for
sensory and motor impulses
.Pons
Located immediately
below the midbrain
.
Plays a role in
regulating breathing
.
Brain Stem
Slide48Medulla oblongataInferior to the PonsRegulates heart rate
, blood pressure etc. and controls reflexes for coughing,
sneezing
and vomiting.
Slide49Found below the occipital lobe.Serves the important role of coordinating body movements, including balance
.Cerebellum
Slide50Functions of the Brain
Slide51The Brain
Meninges
are the
three protective layers that surround the brain and spinal cord
.
Dura mater
Tough double layer outer membrane.
Located
beneath the skull
and surround the brain.
Slide52Arachnoid materMiddle membrane composed of web-like tissue
Beneath this membrane is the subarachnoid space, filled with cerebrospinal fluid, which cushions the brain and spinal cordPia materInnermost layer that
attaches to the surface of the brain and the spinal cord
Slide53Slide54The Brain
Blood-brain barrier
A rich
network of blood vessels supplies the brain
.
At
any given time,
roughly 20%–25% of the blood in your body is circulating in the region of the brain
.
These blood vessels are
specifically impermeable
to many substances.
Slide55The blood-brain barrier protects the brain against surges in concentrations of hormones, ions, and some nutrients.Substances
allowed to pass through the capillaries include water, glucose, and
essential amino acids
. Other substances that can penetrate the blood-brain barrier are
blood-borne alcohol
,
nicotine
,
fats
,
respiratory gases
, and
anesthetics
.
https://www.youtube.com/watch?v=Fc0a71F5Pgw
The Brain
Slide56Extends from the brain stem down to the beginning of the lumbar region of the spine.Serves as a
major pathway for relaying sensory impulses to the brain and
motor
impulses from
the
brain
.
It provides the
neural connections involved in reflex arcs
Spinal Cord
Slide57True 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.
Review and Assessment
False
True
True
True
False
Slide58Lesson 6.4
Functional Anatomy
of the Peripheral
Nervous System
Chapter 6: The Nervous System
Slide59Each nerve consists of a collection of axons (nerve fibers) and nutrient-supplying blood vessels, all bundled in a series of protective sheaths of connective tissue.Endoneurium
Covers axonsPerineurium Bundles fasciclesEpineurium Wraps nerves (groups of fascicles & blood vessels)
Nerve Structure
Slide60Twelve pairs of cranial nerves relay impulses to and from the left and right sides of the brain.These pairs are referred to by both a name and a number.Some of these nerves contain only afferent (sensory) fibers, some contain only efferent (motor) fibers, and others are mixed.
Cranial Nerves
Slide61Cranial Nerves
Slide62Cranial Nerves
Slide63Thirty-one pairs of spinal nerves branch out from the left and right sides of the spinal cord.Each pair is named for the vertebral level from which it originates.
Dorsal rootVentral rootDorsal ramusVentral ramusPlexuses
Spinal Nerves and Nerve Plexuses
Slide64Sympathetic nervesActivate the fight-or- flight response by stimulating the adrenal gland to release epinephrine, also known as adrenaline
.Parasympathetic nervesControls all of the automatic, day-in-and-day- out functions of the circulatory, respiratory, and digestive systems.Sometimes called the “resting and digesting system”.
Autonomic Nervous System
Slide65Lesson 6.5
Injuries and Disorders of the Nervous System
Chapter 6: The Nervous System
Slide66The brain and spinal cord are well protected in a skull and vertebral column respectively as well as surrounded by the meninges.
Injuries to the Brain and Spinal Cord
Slide67Can occur when the skull is pierced or fractured and bone fragments penetrate the brain.MildPerson may lose consciousness for a short period of time, headache, confusion dizziness etc.
Moderate All listed above including: prolonged headache, repeated nausea or vomiting, convulsions etc.
Traumatic Brain Injury (TBI)
Slide68SevereAll above including: Inability to awaken from sleep, slurred speech, numbness in the extremities, agitation Ex. The case of Phineas Gage
Slide69Group of nervous system disorders caused by damage to the brainBefore birthDuring birth
During infancy The most common symptoms involve:Varying degrees of motor function impairment Including hearing, seeing, and cognitive impairment.
Cerebral Palsy (CP)
Slide70Fractures or displacements of the vertebrae can result in injury to the spinal cord.A complete severing of the spinal cord produces permanent paralysis, with a total lack of sensory and motor function below the point of injury.
C1–C3: usually fatalC1–C4
: quadriplegia
C5–C7
: paralysis of lower
extremities
T
1
–L
5
: paraplegia
Spinal Cord Injuries
Corepics/Shutterstock.com
Slide71MeningitisAn inflammation of the meninges surrounding the brain and spinal cord.Multiple sclerosis
An autoimmune disease in which the body’s own immune system causes inflammation that destroys the myelin sheath of nerve cell axons.EpilepsyA group of brain disorders characterized by repeated seizures over time.
Common Diseases and Disorders of the CNS
Slide72Parkinson’s disease (PD)Characterized by slow but progressive destruction of the brain cells responsible for production of the neurotransmitter dopamine, which plays a role in motor function.
Dementia and Alzheimer’s disease (AD)Dementia can be caused by disruption in the blood supply to the brain, as in stroke or related disorders.AD, is a progressive loss of brain function with major consequences for memory, thinking, and behavior.
Common Diseases and Disorders of the CNS
Slide73Match these words with 1–4 below: quadriplegia, multiple sclerosis, dementia, cerebral palsy.
1. Inflammation destroys myelin sheath2. Loss of memory and thinking3. Loss of function below the neck
4. May begin before birth
Review and Assessment
Multiple sclerosis
Dementia
Quadriplegia
Cerebral palsy