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Nervous System

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Chapter 38 Nervous System Learning Objectives Describe the evolution of nervous system List the functions and location of the cerebrum, thalamus, hypothalamus ... – PowerPoint PPT presentation

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Title: Nervous System


1
Chapter 38
  • Nervous System

2
Learning Objectives
  • Describe the evolution of nervous system
  • List the functions and location of the cerebrum,
    thalamus, hypothalamus, midbrain, cerebellum,
    pons, medulla oblongata, basal nucleii, amygdala
    and hippocampus of the limbic system
  • Differentiate the somatic and autonomic systems
  • Diagram the spinal reflex circuit
  • Differentiate functions of the left and right
    hemisphere

3
Learning Objectives
  • Diagram the lobes of the cerebrum according to
    function and anatomy
  • Discuss the process of memory
  • Debate the existence of consciousness
  • Explain the various types of neurological
    disorder incidence and symptoms

4
Invertebrate Nervous Systems (1)
  • Simplest nervous systems The nerve nets of
    cnidarians
  • Echinoderms have modified nerve nets, with some
    neurons grouped into nerves

5
Invertebrate Nervous Systems (2)
  • Flatworms, arthropods, and mollusks have a simple
    central nervous system (CNS)
  • Ganglia in the head region (brain)
  • Peripheral nervous system (PNS)
  • Nerve cords from central ganglia to rest of body

6

c. Planarian (?atworm)
Eyespot
Ganglia
Longitudinal nerve cords
Fig. 38.1c, p. 869
7

d. Arthropod (grasshopper)
Dorsal ganglia
Ventral ganglion
Ganglia of ventral nerve cord
Fig. 38.1d, p. 869
8

e. Mollusk (octopus)
Ganglia associated with internal organs
Optic lobe
Frontal lobes
Lobed brain
Eye
Fig. 38.1e, p. 869
9
Chordate Nervous Systems
  • CNS
  • Large brain located in the head
  • Hollow spinal cord
  • PNS
  • All the nerves and ganglia connecting CNS to the
    rest of the body

10
Development in Vertebrates
  • Vertebrate embryo
  • Anterior end of neural tube develops into brain
  • Rest develops into spinal cord
  • Embryonic brain enlarges into forebrain,
    midbrain, and hindbrain
  • Develop into adult structures

11

Regions in 4-week embryo
Regions in adult
Regions in 5-week embryo
Functions in adult
Neural tube
Higher functions, such as thought, action, and
communication
Telencephalon (cerebrum)
Telencephalon
Coordinates sensory input and relays it to
cerebellum
Forebrain
Thalamus
Diencephalon
Hypothalamus
Center for homeostatic control of internal
environment
Coordinates involuntary reactions and relays
signals to telencephalon
Midbrain
Mesencephalon
Midbrain
Integrates signals for muscle movement
Cerebellum
Hindbrain
Metencephalon
Pons
Center for information flow between cerebellum
and telencephalon
Medulla oblongata
Controls many involuntary tasks
Myelencephalon
Fig. 38.2a, p. 870
12

Hypothalamus
Hemisphere of cerebrum
Thalamus
Brain stem Midbrain
Pons
Cerebellum
Medulla oblongata
Spinal cord
Central canal
Adult brain regions
Fig. 38.2e, p. 870
13
The Peripheral Nervous System
  • Somatic system controls skeletal muscles
  • Voluntary body movements
  • Involuntary muscle contractions that maintain
    balance, posture, muscle tone
  • Autonomic system controls involuntary functions
  • Sympathetic system
  • Parasympathetic system

14

Parasympathetic Division
Sympathetic Division
Constricts pupil adjusts eye for near vision
Dilates pupil adjusts eye for far vision
Optic nerve
Eyes
Eyes
Cranial nerves
Stimulates secretion
Salivary glands
Salivary glands
Inhibits secretion
Vagus nerve
Decreases heart rate
Increases heart rate
Heart
Heart
Constricts bronchioles (airways)
Lungs
Dilates bronchioles
Lungs
Stimulates stomach activity
Stomach
Inhibits stomach activity
Stomach
Inhibits glucose release
Liver
Stimulates glucose release
Liver
Stimulates activity
Intestines
Intestines
Inhibits activity
Stimulates contraction (emptying)
Relaxes bladder muscles
Bladder
Bladder
Inhibits penile or clitoral arousal
Stimulates penile or clitoral arousal
Chain of sympathetic ganglia
Genitals
Genitals
Spinal nerves
Fig. 38.4, p. 872
15
The Spinal Cord
  • Carries signals between the brain and the PNS
  • Its neuron circuits control reflex muscular
    movements and some autonomic reflexes

16

2 The afferent neuron transmits the impulses to
the spinal cord.
3 Interneurons integrate the information.
1 A pain receptor in the finger stimulates an
afferent neuron.
Interneuron connections leading to brain
Integrating interneurons in spinal cord
Stimulus
Ganglion
Spinal nerve
Central canal
Gray matter
White matter
Biceps muscle (?exor) contracts
Response
4 One efferent neuron stimulates the flexor
muscle to contract.
Hand withdrawn
5 The other efferent neuron sends inhibitory
signals that keep the extensor muscle from
contracting.
Effector
Triceps muscle (extensor) relaxes
6 The ?exor contracts, withdrawing the hand from
the pain.
Fig. 38.5, p. 873
17
Major Brain Structures
  • Cerebrum
  • Brain stem
  • Medulla
  • Pons
  • Midbrain
  • Thalamus and hypothalamus

18
Structures of the Cerebrum
  • Right and left cerebral hemispheres
  • Connected by corpus callosum
  • Cerebral cortex
  • Thin gray matter covering core of white matter
  • Basal nuclei
  • Collections of gray matter deep in telencephalon

19
Protecting the CNS
  • Cerebrospinal fluid provides nutrients and
    cushions the CNS
  • A blood-brain barrier allows only selected
    substances to enter the cerebrospinal fluid

20

Layer of cerebrospinal fluid between meninges
Ventricles
Central canal of spinal cord
Cerebral cortex (gray matter)
White matter
Corpus callosum
Basal nuclei (gray matter)
Thalamus
Ventricles
Right cerebral hemisphere
Left cerebral hemisphere
Fig. 38.6, p. 874
21
Functions of the Brain Stem
  • Gray-matter centers in pons and medulla control
    involuntary functions
  • Centers in midbrain coordinate responses to
    visual and auditory sensory inputs
  • Reticular formation
  • Receives sensory inputs from the body
  • Sends outputs to cerebral cortex that help
    maintain balance, posture, muscle tone
  • Regulates states of wakefulness and sleep

22

Midbrain
Cerebellum
Pons
Medulla
Reticular formation
Fig. 38.8, p. 875
23

Front of brain
Fig. 38.7, p. 875
24
Functions of the Cerebellum
  • Integrates sensory inputs to coordinate body
    movements
  • Positions of muscles and joints
  • Visual and auditory information

25
The Telencephalons Subcortical Gray-Matter
Centers
  • Thalamus
  • Receives, filters, and relays sensory and motor
    information to/from regions of cerebral cortex
  • Hypothalamus
  • Regulates basic homeostatic functions of body
  • Contributes to endocrine control of body
    functions
  • Basal nuclei
  • Affect fine-tuning of body movements

26
The Limbic System
  • Structures
  • Parts of thalamus, hypothalamus, basal nuclei
  • Amygdala and hippocampus
  • Functions
  • Controls emotions
  • Influences basic body functions controlled by
    hypothalamus and brain stem

27

Cerebrum
Thalamus Gathers sensory information before
distribution to higher areas
Basal nuclei
Hippocampus Involved mainly with memory
Olfactory bulbs
Hypothalamus
Amygdala Controls emotions, activates fight or
flight self-preservation reactions
Fig. 38.9, p. 876
28
The Cerebral Cortex
  • Primary somatosensory areas
  • Register information on touch, pain, temperature,
    and pressure from all parts of the body
  • Right cerebral hemisphere receives sensory
    information from left side of body and vice versa
  • Primary motor areas control voluntary movements
    of skeletal muscles

29

Front
Primary somatosensory area of left hemisphere
Primary motor area of left hemisphere
Back
Left hemisphere
Left hemisphere
Cross-sectional view
Cross-sectional view
Fig. 38.11, p. 878
30
Association Areas of Cerebral Cortex
  • Integrate sensory information and formulate
    responses passed on to primary motor areas
  • Wernickes area
  • Integrates visual, auditory, other sensory
    information into comprehension of language
  • Brocas area
  • Coordinates movements of lips, tongue, jaws,
    other structures to produce sounds of speech

31

General motor association area
Primary motor area
Frontal Association area (planning,personality)
Primary somatosensory area
General sensory association area
Parietal lobe
Wernickes area (understanding language)
Frontal lobe
Taste
Visual association area
Occipital lobe
Smell
Temporal lobe
Brocas area (expressing language)
Primary visual cortex (visual input)
Auditory area (hearing input)
Cerebellum
Auditory association area
Facial recognition area (on inner side of cortex)
Brain stem
Fig. 38.10, p. 877
32
Lateralization of the Cerebral Hemispheres
  • Left hemisphere functions
  • Spoken and written language, abstract reasoning,
    precise mathematical calculations
  • Right hemisphere functions
  • Nonverbal conceptualizing, mathematical
    estimation, intuitive thinking, spatial
    recognition, artistic and musical abilities
  • Equal functions
  • Long-term memory and consciousness

33
Memory
  • Storage and retrieval of a sensory or motor
    experience or thought
  • Short-term memory involves temporary storage of
    information
  • Long-term memory is essentially permanent

34
Learning
  • Modification of a response through comparisons
    made with information or experiences stored in
    memory

35
Consciousness
  • Awareness of ourselves, our identity, and our
    surroundings
  • Varies through states from full alertness to
    sleep
  • Controlled by the reticular activating system

36

Awake (beta waves)
Eyes closed, relaxed (alpha waves)
Dozing (theta waves)
Deep sleep (delta waves)
Time (sec)
Fig. 38.13, p. 882
37
Major Diseases of the Brain
  • Autism Spectrum Disorder
  • ADHD
  • Alzheimers Disease/Dementia
  • Schizophrenia

38
Autism Spectrum Disorder
  • In 2006, 1 or one child in every 110 was
    classified as having an ASD
  • Males 170 females 1315.
  • Increased 57 from 2002
  • (Rice, December 18, 2009 / 58(SS10)1-20).

39
ASD
  • People with autistic disorder usually have
    significant language delays, social and
    communication challenges, and unusual behaviors
    and interests
  • People with Asperger syndrome usually have some
    milder symptoms of autistic disorder.  They might
    have social challenges and unusual behaviors and
    interests.  However, they typically do not have
    problems with language or intellectual disability.

40
ADHD
  • 4.5 million children 5-17 years of age have ever
    been diagnosed with ADHD as of 2006.
  • 3-7 of school-aged children suffer from ADHD.
    Some studies have estimated higher rates in
    community samples
  • Boys (9.5) are more likely than girls (5.9) to
    have been diagnosed with ADHD. Diagnosis of ADHD
    increased an average of 3 per year from 1997 to
    2006
  • (http//www.cdc.gov/ncbddd/adhd/data.html)

41
Types of ADHD
  • Predominantly Inattentive Type
  • Lack of organization or finish a task,
  • Unable to pay attention to details, or to follow
    instructions or conversations.
  • Easily distracted or forgets details of daily
    routines.  
  • Predominantly Hyperactive-Impulsive Type
  • fidgets and talks a lot.
  • hard to sit still for long (e.g., for a meal or
    while doing homework).
  • Smaller children may run, jump or climb
    constantly.
  • Feels restless and has trouble with impulsivity.
  • May interrupt others a lot, grab things from
    people, or speak at inappropriate times
  •  
  • Combined Type Symptoms of the above two types
    are equally present in the person

42
Alzheimers Disease/Dementia
  • About 5 ages 65-74 year old
  • About 50 over 80 years old
  • An estimated 5 million Americans have Alzheimers
    disease.
  • This number has doubled since 1980
  • It is expected to be as high as 13.4 million by
    2050
  • Individuals with Alzheimers disease make up less
    than 13 percent of the Medicare population, yet
    they account for 34 percent of Medicare
    spending.
  • How old will you be in 2050? Who is paying the
    bill?

43
Schizophrenia
  • Affects 1.1 percent of the population
  • Onset usually after age 18
  • Later in women
  • Often addicted to nicotine and other substances
  • Genetically linked

44
Symptoms
  • Positive
  • Hallucinations (voices are common)
  • Delusions (religious or alien, or authority)
  • Thought disorders
  • Movement disorders
  • Negative
  • Absence of pleasure, planning, enjoyment
    (affect), speaking, etc.
  • Cognitive defects
  • Little understanding, trouble focusing, and
    little memory
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