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Consists of all the nerve cells. It is the body's speed, electrochemical communication system
Central Nervous System (CNS)
brain and spinal cord
Peripheral nervous system (PNS)
the sensory and motor neurons that connect the CNS to the rest of the body
consist of neural "cable"containing many axons. They are part of the PNS and connect muscles, glands, and sense organs to the CNS
Basic unit of the nervous system. Allow communication between the brain and sensory organs, internal organs, and muscles.
Sensory Neurons (Afferent)
Conduct sensory impulses from eyes, ears, and other sense organs to the CNS.
Conduct motor impulse out from the CNS to muscles and organs
Connect one neuron to an other
the cell's life support center
receive messages from other cells
passes messages away fro the cell body to other neurons, muscles, or glands
action potential electrical signal traveling down teh axon
Terminal branches of axon
from junction with other cells
covers the axon of some neurons and helps speed neural impulses
How neurons communicate signals
Electrical-conduction of impulse within neuron
Chemical- transmission of impulse between neurons
Conduction of Impulse
each neuron receives excitatory and inhibitory signals from many neurons. When the excitatory signals minus the inhibitory signals exceed a minimum intensity(threshold) the neurons fires and action potential i.e. electrical impulse passes down the axon with constant intensity
Conduction of impulse
once fires, resting potential returns
Conduction of impulse
Absolute Refractory Period
brief period of time after firing when neuron won't fire
Conduction of impulse
all or none law
Neuron either firing with full intensity of resting (resting potential.) Increases in intensity of stimulation don't cause stronger impulse but lead to more rapid firing or to activation of more neurons.
conduction of impulse
relative refractory period
period of time after firing when neuron will only fire in response to strong stimulation
Transmission of message
small gap between axon of one neuron and the dendrite of another through which chemical messages are transmitted
transmission of message
The end of the axon. Contains synaptic vesicles.
transmission of message
causes vesicle to open and release neurotransmitters(chemicals that have specific different shapes) which travel across synapse and bind to matching receptor sites on receiving neuron, thereby influencing it to generate an action potential
Neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of reuptake.
This process applies the brakes on neurotransmitter action.
Lock and key Mechanism
Neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism
How some drugs work
the agonist molecule excites. It is similar enough in structure to the neurotransmitter molecule that it mimics its effects on the receiving neuron.
Morphine- mimics the actions of endorphins by stimulating receptors in brain areas involved in mood and pain sensations
how some drugs work
this molecule inhibits. it has a structure similar enough to the neurotransmitter to occupy its receptor site and block its action, but not similar enough to stimulate the receptor.
curare poisoning- paralyzes its victims by blocking ach receptors involved in muscle movement
involved in movement, attention, emotion, and learning.
involved with mood, sleep, hunger, and arousal regulation
Enables muscle action, learning, and memory
Alzheimer's desease, ach producing neurons deteriorate
influences movement, learning, attention, and emotion
excess dopamine receptor activity linked to schizophrenia
affects mood, hunger, sleep, and arousal
undersupply linked to depression prozac and some other antidepressant drugs raise serotonin levels
helps control alertness and arousal
undersupply can depress mood
a major inhibitory neurotransmitter
undersupply linked to seizures, tremors, and insomnia
a major excitatory neurotransmitter involved in memory
The body's slow chemical communication system
Consists of glands distributed around body that release hormones into bloodstream.
chemical messengers that influence behavior. ex. epinephrine (adrenaline) increases heart rate & blood pressure during emergency
- Hormones travel longer distances and their effects slower & more prolonged than neurotransmitters (some chemicals can be both.)
brain region controlling the pituitary gland
sit above kidneys, secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.
secretes male sex hormones
secretes female hormones
- secretes many different hormones, some of which affect other glands
- regulates growth.
help regulate teh level of calcium in the blood
regulates the level of sugar in the blood
The spinal cord and reflexes
- 1. information is carried from skin receptors along a sensory neuron to the spinal cord. From here it is passes via interneurons to motor neurons that lead to muscles in the hand and arm
- 2. this reflex involves or spinal cord, the hand jerks away from candle flame even before informing it about the event has reached the point of causing the experience of pain
Computerized Axial Tomography (CT or CAT scan)
a series of x-ray photographs taken from different angles and combined by computer into a 3d composite representation of the brain
- used to detect tumors and stroke damage
- CTs have been useful in identifying schizophrenia patients. In these patients' brains: the ventricles (fluid- filled open spaces), are significantly larger than in normal individuals, which means that they have less brain tissue to process cognitive functions.
- Instead of a flat, two-dimensional X-ray picture, CT scanners produce a series of successive images. Taken as the patient, lying down, moves through a scanning ring, these "slices" can be combined to create the illusion of a 3-D image.
- Detects such things as tumors & stroke damage.
- - An amplified recording of the electrical waves sweeping across the brain’s surface, measured by electrodes placed on the scalp.
- - Brain activity is plotted as a line (Brain wave).
- - Used in sleep and other kinds of brain research.
MRI Scan Magnetic Resonance Imaging
- - Uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of brain tissue.
- - Allows us to see structures within the brain - Used for diagnosing tumors and epilepsy.
- measures brain function. It tracks brain activity by monitoring changes in how much oxygen the brain cells are consuming. That serves as an indicator of how much blood is flowing to various brain regions, which in turn shows how active the neurons are.
- •Typically, fMR subjects are placed in an MRI machine and asked to perform a mental task such as remembering and repeating words presented to them.
Postion Emission tomography PET
- - A visual display of brain metabolic activity.
- - Detects where a radioactive form of glucose travels while the brain performs a given task.
- - Useful for identifying changes in mental activity & in blood flow.
- A naturally or experimentally caused destruction of brain tissue.
- Researchers study change in behaviors after such destruction.
Attention, arousal, wakefulness
Heartbeat, breathing, digestion, and vital reflexes (sneezing, vomiting, swallowing, coughing, etc.)
Sensory hub. Processes most sensory info to sensory areas in cortex, and transmits replies to cerebellum and medulla.
- The “little brain” attached to the rear of the brainstem
- Helps coordinate voluntary movements and balance, ex. playing the piano, kicking, throwing
- Also coordinates cognitive processes
The Limbic System: Emotions & Drives
Doughnut-shaped system of neural structures at border of brainstem and cerebrum
Hypo (i.e. below) thalamus
- regulates maintenance activities (ex. sleep, body temperature, hunger, thirst, circadian rhythm, salt & water balance) and sexual behavior.
- Helps govern hormone secretion by endocrine system via pituitary gland.
involved in emotional responding (fear, anger). Reads emotional significance of input from all senses. Output influences such functions as heart rate, adrenaline release. If damaged, hard to identify emotion from facial expressions
involved in forming new memories
As the teens got older, the center of activity shifted more toward the frontal cortex which governs reason and analysis and away from the cruder amygdala which governs emotional “gut” reactions
- Two Cerebral Hemispheres identical in appearance & work together but have somewhat differing
Nonverbal, spatial, perceptual, holistic & emotional functions.
Linguistic,mathematical, analytical functions.
cross over in spinal cord
: connects 2 hemispheres • Lateralization is never 100%
- Most advanced, complex functions
- Outer wrinkled part. Body’s ultimate control center.
axon fibers connecting the two cerebral hemispheres
relays messages between lower brain centers and cerebral cortex
- controls maintenance functions such as eating
- helps govern endocrine system
- linked to emotion and reward
master endocrine gland
helps control arousal
controls hearth beat and breathing
- pathway for neural fibers
- traveling to and from brain
- controls simple reflexes
coordinates voluntary movements and balance and supports memories of such
ultimate control and information processing center
linked to emotion
linked to memory
Splitting the Brain
- A procedure in which the two hemispheres of the
- brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them.
Split brain patients
With the corpus callosum severed, objects (apple) presented in the right visual field can be named. Objects (pencil) in the left visual field cannot.
The four lobes of the cortex
Each brain hemisphere is divided into 4 lobes separated by prominent fissures
movement (motor cortex) & thinking
Touch & movement sensations (sensory cortex)
hearing (auditory cortex), emotion, memory
controls voluntary movements.
receives information from skin surface and sense organs.
The functional MRI scan shows the visual cortex is active as the subject looks at faces.
Aphasia is an impairment of language, usually caused by left hemisphere damage either to Broca’s area (impaired speaking) or to Wernicke’s area (impaired understanding). understanding).
recieves written words as visual stimulation
transforms visual representation sinto an auditory code
interprets auditory code
controls speech muscles via the motor cortex
word is pronounced
More intelligent animals have increased “uncommitted” or association areas of the cortex.
auditory cortez and Wernick's area
visual cortex and angular gyrus
broca's area and motor cortex
The brains placidity
- The brain is sculpted by our genes but also by our experiences.
- Plasticity refers to the brain’s ability to modify itself after some types of injury or illness.
Somatic nervous system
The division of the peripheral nervous system that controls the body’s skeletal muscles.
Autonomic Nervous system
Part of the PNS that controls the glands and other muscles.
(ANS) Sympathetic NS
arouses the body, mobilizing its energy in stressful situations (fight-or- flight)
Parasympathetic NS (ANS)
calms the body, conserving its energy (rest and digest)
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