Chapter 38
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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, midbrain, cerebellum, pons, medulla oblongata, basal nucleii, amygdala and hippocampus of the limbic system

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Chapter 38

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Chapter 38

Chapter 38

Nervous System


Learning objectives

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


Learning objectives1

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


Invertebrate nervous systems 1

Invertebrate Nervous Systems (1)

  • Simplest nervous systems: The nerve nets of cnidarians

  • Echinoderms have modified nerve nets, with some neurons grouped into nerves


Invertebrate nervous systems 2

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


Chapter 38

c. Planarian (flatworm)

Eyespot

Ganglia

Longitudinal nerve cords

Fig. 38.1c, p. 869


Chapter 38

d. Arthropod (grasshopper)

Dorsal ganglia

Ventral ganglion

Ganglia of ventral nerve cord

Fig. 38.1d, p. 869


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e. Mollusk (octopus)

Ganglia associated with internal organs

Optic lobe

Frontal lobes

Lobed brain

Eye

Fig. 38.1e, p. 869


Chordate nervous systems

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


Development in vertebrates

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


Chapter 38

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

Center for homeostatic control of internal environment

Hypothalamus

Coordinates involuntary reactions and relays signals to telencephalon

Mesencephalon

Midbrain

Midbrain

Integrates signals for muscle movement

Cerebellum

Metencephalon

Hindbrain

Pons

Center for information flow between cerebellum and telencephalon

Medulla oblongata

Controls many involuntary tasks

Myelencephalon

Fig. 38.2a, p. 870


Chapter 38

Hypothalamus

Hemisphere of cerebrum

Thalamus

Brain stem: Midbrain

Pons

Cerebellum

Medulla oblongata

Spinal cord

Central canal

Adult brain regions

Fig. 38.2e, p. 870


The peripheral nervous system

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


Chapter 38

Parasympathetic Division

Sympathetic Division

Constricts pupil; adjusts eye for near vision

Dilates pupil; adjusts eye for far vision

Optic nerve

Eyes

Eyes

Cranial nerves

Salivary glands

Stimulates secretion

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


The spinal cord

The Spinal Cord

  • Carries signals between the brain and the PNS

  • Its neuron circuits control reflex muscular movements and some autonomicreflexes


Chapter 38

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 (flexor) 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 flexor contracts, withdrawing the hand from the pain.

Fig. 38.5, p. 873


Major brain structures

Major Brain Structures

  • Cerebrum

  • Brain stem

    • Medulla

    • Pons

    • Midbrain

  • Thalamus and hypothalamus


Structures of the cerebrum

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


Protecting the cns

Protecting the CNS

  • Cerebrospinal fluid provides nutrients and cushions the CNS

  • A blood-brain barrier allows only selected substances to enter the cerebrospinal fluid


Chapter 38

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


Functions of the brain stem

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


Chapter 38

Midbrain

Cerebellum

Pons

Medulla

Reticular formation

Fig. 38.8, p. 875


Chapter 38

Front of brain

Fig. 38.7, p. 875


Functions of the cerebellum

Functions of the Cerebellum

  • Integrates sensory inputs to coordinate body movements

    • Positions of muscles and joints

    • Visual and auditory information


The telencephalon s subcortical gray matter centers

The Telencephalon’s 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


The limbic system

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


Chapter 38

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


The cerebral cortex

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


  • Chapter 38

    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


    Association areas of cerebral cortex

    Association Areas of Cerebral Cortex

    • Integrate sensory information and formulate responses passed on to primary motor areas

    • Wernicke’s area

      • Integrates visual, auditory, other sensory information into comprehension of language

    • Broca’s area

      • Coordinates movements of lips, tongue, jaws, other structures to produce sounds of speech


    Chapter 38

    General motor association area

    Primary motor area

    Frontal

    Association area

    (planning,personality)

    Primary somatosensory area

    General sensory association area

    Parietal lobe

    Wernicke’s area (understanding language)

    Frontal lobe

    Taste

    Visual association area

    Occipital lobe

    Smell

    Temporal lobe

    Broca’s 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


    Lateralization of the cerebral hemispheres

    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


    Memory

    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


    Learning

    Learning

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


    Consciousness

    Consciousness

    • Awareness of ourselves, our identity, and our surroundings

    • Varies through states from full alertness to sleep

    • Controlled by the reticular activating system


    Chapter 38

    Awake

    (beta waves)

    Eyes closed, relaxed (alpha waves)

    Dozing

    (theta waves)

    Deep sleep (delta waves)

    Time (sec)

    Fig. 38.13, p. 882


    Major diseases of the brain

    Major Diseases of the Brain

    • Autism Spectrum Disorder

    • ADHD

    • Alzheimer’s Disease/Dementia

    • Schizophrenia


    Autism spectrum disorder

    Autism Spectrum Disorder

    • In 2006, 1% or one child in every 110 was classified as having an ASD

    • Males: 1:70; females: 1:315.

    • Increased 57% from 2002

      (Rice, December 18, 2009 / 58(SS10);1-20).


    Chapter 38

    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.


    Chapter 38

    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)


    Types of adhd

    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


    Alzheimer s disease dementia

    Alzheimer’s Disease/Dementia

    • About 5% ages 65-74 year old

    • About 50% over 80 years old

    • An estimated 5 million Americans have Alzheimer’s disease.

    • This number has doubled since 1980

    • It is expected to be as high as 13.4 million by 2050

    • Individuals with Alzheimer’s 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?


    Schizophrenia

    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


    Symptoms

    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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