Download Electrical Communication (Nervous System) ppt

PARTS OF THE
BRAIN
Parts of the Brain
Cerebrum- higherorder thinkingintelligence,
memory, sensory
processing
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2 halves
connected by
corpus callosum
4 lobes- frontal,
parietal,
temporal,
occipital
Lobes are in the
same location as
corresponding
skull bone
Lobes
◦ Frontal Lobe◦ Consciousness, judgement, language, emotion,
concentration, problem-solving
◦ Broca’s Area- coordinates muscle movement for
speech
◦ Parietal (Par-eye-it-all) Lobe◦ Integrating sensory information, hand-eye
coordination
◦ Temporal (Temp-oral) Lobe◦ Smell and sound, memory of visual and auditory
patterns
◦ Occipital (Ox-ip-it-all) Lobe◦ Vision
Hemisphere Dominance
◦ Each hemisphere controls motor function for
opposite side of body, dominant hemisphere
opposite from dominant hand
◦ Dominant (usually left) controls speech, reading,
writing, analytical
◦ Non-dominant- emotions, intuition, creativity
Diencephalon
◦ Located between cerebrum and midbrain
◦ Glands contained in diencephalon:
◦ Thalamus- receives sensory impulses, general
awareness of touch sensations
◦ Hypothalamus- homeostasis- controls hunger, heart
rate, temperature, sleep, etc
◦ Pituitary gland- endocrine gland, secretes
important hormones
◦ Pineal gland- endocrine gland, produces
melatonin (related to sleep)
Parts of the Brain, cont’d
Cerebellum- Balance, posture, coordinates
muscle movement
BrainstemMidbrain- visual and auditory reflex centers
Pons- regulates breathing, relays nerve impulses
from peripheral nerves to brain
Medulla Oblongata- regulates heart rate,
breathing, blood pressure (sends signals to these
functions, while hypothalamus has more of a
control function)
Brain Check-up...
1. What part of your brain contains your
higher-order thinking skills?
2. If you are trying to recognize
someone’s face, what area of your
brain is going to be active?
3. If you are hungry, what part of your
brain is signaling that?
THE SPINAL CORD
AND NERVES
Meninges-membranes that surround and
protect brain and spinal cord, 3 layers:
◦ Dura mater- outermost, tough connective
tissue, blood vessels and nerves
◦ Arachnoid mater- thin, in middle
◦ Pia mater- very thin, innermost, many nerves
and blood vessels serve brain and spinal cord
Spinal Cord
◦ Thick bundle of nerves passing through
opening at base of skull down through
vertebral column
◦ 31 pairs of spinal nerves branch off, control
limbs and trunk
◦ Two-way communication system:
◦ Ascending tracts: carry sensory info to brain
◦ Descending tracts: carry nerve impulses from brain
to muscles
Peripheral Nervous
System
Nerves that branch
out from CNS and
connect it to body
parts
Two parts:
Somatic Nervous
System- connects to
skin and skeletal
muscle, conscious
activities
Autonomic Nervous
System- connects to
organs such as heart,
stomach, intestines;
unconscious activities
Central Nervous
System
Brain and Spinal Cord
Cranial
Nerves -
originate
from
brainstem,
12 pairs,
control
face and
neck
Nerve Plexus
◦ Spinal nerves organized
into plexuses- complex
network of nerves, sort
and recombine nerve
fibers to correspond to
each body part
Autonomic Nervous System
Controls heart rate, blood pressure, all
unconscious activities
2 PartsSympathetic- response to stress, “fight or flight”speeds up heart, breathing, more blood to skeletal
muscle
Parasympathetic- relaxation, slows down heart,
breathing, more blood to digestive organs
◦ Central nervous system
◦ Peripheral nervous system
Organize these
terms into a
concept map in
your notes...think
about how they
are related
hierarchically
◦ Parasympathetic nervous system
◦ Sympathetic nervous system
◦ Autonomic nervous system
◦ Brain
◦ Spinal cord
◦ Nerve Plexuses
◦ Meninges
◦ Cerebellum
◦ Cerebrum
◦ Frontal Lobe
◦ Occipital Lobe
◦ Parietal Lobe
◦ Temporal Lobe
◦ Brain Stem
ANATOMY OF A
NEURON
Neuron (Nerve Cell)
Parts of the Neuron
Dendrites- receive nerve impulses
Cell Body
Nucleus
Axon- sends nerve impulses, coated in myelin sheath
Axon Terminals- contact receptors of other cells
Myelin- whitish, fatty material that insulates axon and
speeds up signal transmission
◦ Schwann cells- cells wrapped around axon like a jelly
roll, makes up myelin sheath
◦ Nodes of Ranvier- gaps between Schwann cells
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If a cell body were the size of a tennis ball,
the axon would be a mile long
Types of Neurons
1. Sensory Neurons (afferent neurons)- cell
bodies found in a ganglion (group of
cell bodies) outside CNS
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Dendrites are receptors (sense organs, pain
receptors, skin receptors, etc)
2. Motor neurons (efferent neurons)- send
messages from CNS to muscles and
glands
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Cell bodies in CNS, long axons
3. Interneurons- connect motor and
sensory neurons, cell bodies located in
CNS
NEURON ACTION
POTENTIALS
Membrane Potential
◦ Charge difference between inside and outside
of cell (called potential difference)
◦ Larger concentration of Na+ ions outside cell
and K+ ions inside cell causes charge
◦ In a resting nerve cell, potential difference is
called resting potential
◦ Normal resting potential is -70 millivolts (mV)
Action Potential
◦ Change in neuron
membrane polarization
and return to resting state
is called an action
potential
◦ Chain of action potentials
form nerve impulse
Action Potential
◦ Stimuli (temperature, light, pressure, other neurons) decrease
membrane potential
◦ Decrease is called depolarizing
◦ When threshold potential (-55 mV) is reached, stimulus is big
enough to cause neuron to send a signal
◦ Threshold triggers Na+ and K+ channels located in nodes of
Ranvier to open and equalize charges
◦ Na+ channels open faster, causing rapid depolarization
◦ As K+ channels open, membrane becomes negatively charged
once more (becomes repolarized)
◦ Adjacent portions of axon are triggered and action potentials
propagate down length of axon, making a nerve impulse
◦ Signal “jumps” across Schwann cells from one Node of Ranvier
to another
◦ For a short time following impulse (1-2 milliseconds), a refractory
period follows, when membrane returns to resting potential and
no action potential can be triggered
Action Potential Video
◦ https://www.youtube.com/watch?v=7EyhsOewnH4
SYNAPSES AND
NEUROTRANSMITTERS
What is a synapse?
◦ Synapse: gap between two neurons
◦ Presynaptic neuron: neuron sending impulse
◦ Postsynaptic neuron: neuron receiving impulse
Synaptic Transmission
◦ Neurotransmitter: chemicals that carry out synaptic
transmission
◦ When action potentials reach axon terminals,
neurons release neurotransmitters from vesicles
◦ Neurotransmitters travel across synapse, attach to
receptors on postsynaptic neuron dendrites
Neurotransmitters
◦ 2 types:
◦ Excitatory- raise membrane potential
◦ Inhibitory- lower membrane potential
◦ Each neurotransmitter can be EXITATORY and INHIBITORY
depending on what downstream neuron it is impacting.
◦ Examples:
◦ Acetylcholine- excitatory, muscle contraction
◦ Norepinephrine- excitatory, increases sense of well-being,
concentration
◦ Serotonin- inhibitory, causes sleepiness
◦ Dopamine- inhibitory, increases sense of well-being, pleasure