Transcript Nervous System

Nervous System
Functions of the Nervous System
1.
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3.
4.
sensory input (monitor stimuli)
integration
motor output (respond to stimuli)
mental activity (consciousness, memory
thinking)
5. control of muscles and glands
Divisions of Nervous System
1. central nervous system (CNS)
• brain and spinal cord
• command center of body
• integrates response based on past
experiences and conditions
Divisions of the Nervous System
2. peripheral nervous system (PNS)
• nerves leading into/out of brain and spinal
cord, including ganglia
• communication lines to the body
– sensory (afferent) neurons – carry info from
sensory receptors to CNS
– motor (efferent) neurons – carry info to viscera
and/or muscles and glands
– association neurons – connect sensory and motor
pathways
Divisions of Nervous System
• Motor division of PNS can be divided into two
parts.
1. somatic nervous system
– nerves leading from CNS to skeletal muscles
2. autonomic nervous system
– nerves leading from CNS to smooth muscle, cardiac
muscle, and viscera (glands / internal organs)
– sympathetic division of autonomic
• concerned with increasing overall body activities during
excitement, danger, or times of heightened awareness
– parasympathetic division of autonomic
• slows down body functions and diverts energy to basic tasks,
in times of low stimulus
The Brain
• regions
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brainstem
cerebrum
diencephalon
cerebellum
The Brain
• white matter and gray matter
• gray: areas dominated by cell bodies
– composes cortex
• white: areas dominated by axons
– comes from the myelin sheath that cover the
axons
• gray: information processing centers in the
brain
• white: connections between processing
centers
The Brain
• meninges – membranes layered between
skull bones and brain tissue
• ventricles – communicating cavities of
brain, continuous with central canal of the
spinal cord
ventricles of brain
Brainstem
connects spinal column to
brain
• medulla oblongata
– reflex centers for
respiration and
cardiovascular functions
– complex reflexes
(coughing, vomiting);
– sleeping/waking;
– conscious control of
skeletal muscles
Brainstem
• pons
– provides bridge to CNS
– control of breathing, swallowing, balance,
chewing and salivation
• midbrain – tectum and tegumentum
– coordination center for reflex response to
auditory, visual, tactile responses
Brainstem
• reticular formation
– regulates respiration, walking, chewing
– controls consciousness, sleep/wake cycle
– where anesthesia acts on brain
– damage can result in coma
Diencephalon
• between brainstem and cerebrum
1. thalamus – largest part
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coordinating center for sensory signals
influences mood
perceives sensation as pleasant or unpleasant
2. epithalamus
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emotional and visceral response to odors
contains pineal body – endocrine gland
could signal onset of puberty
3. hypothalamus – homeostatic control
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body temp, hunger, thirst
controls secretions of hormones from pituitary glands
Cerebrum
• largest part of brain
• has 2 hemispheres
with gyri (folds) and
sulci (grooves) that
increase surface area
• center for
coordinating sensory
and motor functions,
memory and for
abstract thought
Lobes of Cerebrum
• frontal
– voluntary motor functions
– intellect and behavior
– aggression/personality
– concentration, planning, problem solving
– olfactory reception
– Broca’s area - only on left side
• language production
Lobes of Cerebrum
• parietal
– reception of conscious perception of sensory
impulses (pain, temp, touch, balance, taste)
– Wernicke’s Area
• language comprehension
• occipital
– visual input reception and perception
Lobes of Cerebrum
• temporal
– olfactory and auditory sensations
– important role in memory
– abstract thought and judgment
– facial recognition
Hemispheres of Cerebrum
• right – sensory input and control of
muscular activity for left side of body
– functional skills
– spatial perception
– music
– abstract thinking
• left – control for right side of body
– analytical skills like math, speech
Corpus Callosum
• connects the right and left hemispheres of
the cerebrum
• coordinates the functions of the two halves
• over 200 million axons
• develops in 5th-16th week of gestation
Corpus Callosum
• https://www.youtube.c
om/watch?v=82tlVcq6
E7A
• Split brain with Alan
Alda
Cerebellum
• “little brain”
• smaller folds and grooves than cerebrum
• balance and posture, maintenance of muscle
tone
• coordinated fine motor movement
• manual dexterity
• spatial orientation
• some language
• alcohol inhibits the functions of the
cerebellum
Blood/Brain Barrier
• Capillaries have tight
junctions so
everything has to go
through cell
membranes.
• protects brain from
harmful substances
• prevents medications
from getting to brain
Limbic System
• scattered brain centers in the middle of
cerebral hemispheres
• controls emotions and emotional
responses
• hormonal secretions
• mood
• motivation
• pain and pleasure sensations
Structures of Limbic System
amygdala
• involved in emotions and motivations
(survival)
• processes fear, anger and pleasure
• determines what memories are stored and
where based on degree of emotional
response
• lesions: remember person but not if you
like him or not
Structures of Limbic System
cingulate cortex
• forms collar around corpus callosum
• anterior portion: cognitive and emotional
responses
• dorsal portion: motor and eye fields
• ventral: emotions and motivation
Structures of Limbic System
hippocampus - left and right
• forms new memories
• connecting emotions and senses to
memories
• storage and retrieval of memories
• damage to both: no memory
Structures of Limbic System
nucleus accumbens
• pleasure center; sexual arousal
• important role in reward, pleasure,
laughter, addiction, aggression, fear, and
the placebo effect
• damage: lack of motivation,
impulsiveness, ADHD, inhibited addictive
behavior
Structures of Limbic System
ventral tegmental area
• sends messages on how needs are being satisfied
• forms reward circuit with nucleus accumbens
• lesions: no gratification from common pleasures
– become alcoholics, gamble, eat sweets compulsively
septum – anterior to thalamus
• center for sexual satisfaction (4 for women; 1 for men)
parts of thalamus – mood, pleasant/unpleasant sensations
hypothalamus – homeostasis; appropriate emotional response