Neuroscience and Behavior Neural Communication Neurons How Neurons Communicate How Neurotransmitters Influence Us The Nervous System The Peripheral Nervous System The Central Nervous System ID: 784546
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Slide1
Neural and Hormonal Systems
Slide2Neuroscience and Behavior
Neural Communication
Neurons
How Neurons Communicate
How Neurotransmitters Influence Us
The
Nervous System
The Peripheral Nervous System
The Central Nervous
System
THE ENDOCRINE SYSTEM
Slide3History of Mind
In 1800,
German physician Franz
Gall suggested that bumps of the skull represented mental abilities. His theory, though incorrect, nevertheless proposed that
various brain regions have particular functions.
Phrenology
Bettman
/ Corbis
Slide4Neural Communication
The body’s information system is built from billions of interconnected cells called
neurons
or nerve cells.
Slide5Neural Communication
Note the similarities in the above brain regions, which are all
engaged in information processing.
Neurobiologists and other investigators understand that humans and animals operate similarly when processing information.
Slide6Neuron
A nerve cell, or a neuron, consists of many different parts.
Slide7Parts of a Neuron
Cell Body:
Life support center of the neuron.
Dendrites
: (tree)
Branching extensions at the cell body. Receive messages from other neurons
. DENDRITES LISTEN
Axon
:
Long single extension of a neuron, covered with
myelin [MY-uh-
lin
] sheath
to insulate and speed up messages through neurons
.
AXONS SPEAK
Terminal
Branches of axon:
Branched endings of an axon that transmit
messages (in neurotransmitters)
to other neurons
.
Soma:
the cell body of the neuron.
Slide8Kinds of Neurons
Sensory Neurons
carry incoming information from the sense receptors to the CNS.
Motor Neurons
carry outgoing information from the CNS to muscles and glands.
Interneurons connect the two neurons.
Sensory Neuron
(Bipolar)
Interneuron Neuron (Unipolar)
Motor Neuron
(Multipolar)
Slide9Action Potential
A neural impulse. A brief electrical charge that travels down an axon and is generated by the movement of positively charged atoms in and out of channels in the axon’s membrane.
Slide10Neurons
Depending on the type of fiber, the neural impulses travel at speeds ranging from a sluggish 2 miles an hour to 200 miles per hour.
Even this top speed is still 3 million times slower than that of electricity through a wire.
Brain is vastly more complicated than a computer, but not faster at executing simple responses.
Slide11Threshold
Threshold:
Each neuron receives
excitatory (like pushing the accelerator) and inhibitory (like pushing the brake)
signals from many neurons. When the excitatory signals minus the inhibitory signals exceed a minimum intensity (threshold) the neuron fires an action potential.
Slide12Action Potential Properties
All-or-None Response
: A neuron always fires with the same intensity.
A strong stimulus can trigger more neurons to fire, and to fire more often, but it does not affect the action potentials strength or speed.Intensity
of an action potential remains the same throughout the length of the axon.**Toilet flushing example
The idea that either the neuron fires or it does not- no part way firing.
Like a gun
Slide13Steps of Action Potential
Dendrites receive neurotransmitter from another neuron across the synapse.
Reached its
threshold
- then fires based on the all-or-none response.Opens up a portal in axon, and lets in positive ions (Sodium) which mix with negative ions (Potassium) that is already inside the axon (thus Neurons at rest have a slightly negative charge).The mixing of + and –
ions causes an electrical charge that opens up the next portal (letting in more K) while closing the original portal.Process continues down axon to the axon terminal.Terminal buttons turns electrical charge into chemical (neurotransmitter) and shoots message to next neuron across the synapse.
Slide14Synapse
Synapse [SIN-aps]
a
junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. This tiny gap is called the synaptic gap or
cleft.
Slide15Neurotransmitters
Neurotransmitters (chemicals) released from the sending neuron travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing it to generate an action potential.
Slide16Reuptake
Neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of reuptake. This process applies the brakes on neurotransmitter action.
Slide17How Neurotransmitters Influence Us
Serotonin pathways are involved with mood regulation.
From
Mapping the Mind,
Rita Carter, © 1989 University of California Press
Slide18Dopamine Pathways
Dopamine pathways are involved with diseases such as schizophrenia and Parkinson’s disease.
From
Mapping the Mind,
Rita Carter, © 1989 University of California Press
Slide19Neurotransmitters
Slide20Lock & Key Mechanism
Neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism.
Slide21Agonists-a drug that boosts the effects of a neurotransmitter
Slide22Antagonists-drug that blocks the effect of a neurotransmitter
Slide23Plasticity
Neurons
have the ability to change—to make new connections and strengthen old ones.
They can adapt/modify as a result of experience.
Ex. Violin player—motor area linked to fingers in left had becomes bigger with experience.
Slide24Glial Cells
A
support group for neurons.
They provide the structural support for the neurons.
They also help in forming new synapsesFound to be crucial to learningThey are what form the myelin sheath.
Slide25Nervous System
Central
Nervous
System
(CNS)PeripheralNervous
System(PNS)
Slide26The Nervous System
Nervous System:
Consists of all the nerve cells. It is the body’s speedy, electrochemical communication system
.
2 Major Parts
Central Nervous System (CNS):
the brain and spinal cord.
Peripheral Nervous System (PNS):
the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.
Slide27The Nervous System
Slide28Peripheral Nervous System
Its like the “pick up and delivery” service for the Central Nervous System. It connects it with the rest of the body through bundles of sensory/motor nerves.
Slide29The Nerves
Nerves consist of neural
“cables”
containing many axons. They are part of the
peripheral nervous system and connect muscles, glands, and sense organs to the central nervous system.
Slide30TWO PARTS TO THE PNS
Somatic Nervous System:
The division of the peripheral nervous system that controls the body’s skeletal muscles
.Afferent: sensory componentEfferent: Motor component
Autonomic Nervous System: Part of the PNS that controls the glands and other muscles. Fight/flight—self-regulating
Slide31Autonomic Nervous System (ANS)
Sympathetic Nervous System:
Division of the ANS that arouses the body, mobilizing its energy in stressful situations
.
AROUSES
Parasympathetic Nervous System: Division of the ANS that calms the body, conserving its energy.
CALMS
Opponent Process System: they work in opposition create homeostasis.
Slide32Autonomic Nervous System (ANS)
Sympathetic NS
“Arouses”
(fight-or-flight)
Parasympathetic NS
“Calms”
(rest and digest)
Slide33Central Nervous System
The Brain and Neural
Networks:
Complex Neural Network
Interconnected neurons form networks in the brain. Theses networks are complex and modify with growth and experience
.
Slide34Central Nervous System
The Spinal Cord and Reflexes
Simple Reflex
Slide35The Endocrine System
The
Endocrine System
is
the body’s “slow” chemical communication system. Communication is carried out by hormones synthesized by a set of glands.
Slide36Hormones
Hormones
are chemicals synthesized by the endocrine glands that are secreted in the
bloodstream. Hormones affect the brain and many other tissues of the body.
These hormones are the same chemical messengers that are used in the nervous system (neurotransmitters)
For
example, epinephrine (
adrenaline)
increases heart rate, blood pressure, blood sugar, and feelings of excitement during emergency situations
. Fight or flight!
Slide37Pituitary Gland
Is called the “master gland.” The anterior pituitary lobe releases hormones that regulate other glands. The posterior lobe regulates water and salt
balance. It is at the base of your brain.
HoweHo
Slide38Pituitary Gland
Although it is the “master gland” of the endocrine system, it is really only a mid-level manager.
It takes its orders from the brain…in particular the Hypothalamus. More on this soon
Slide39Thyroid & Parathyroid Glands
Regulate metabolic and calcium rate.
Slide40Adrenal Glands
Adrenal glands consist of the adrenal medulla and the cortex. The medulla secretes hormones (epinephrine and norepinephrine) during stressful and emotional situations, while the adrenal cortex regulates salt and carbohydrate metabolism.
Slide41Gonads
Sex glands are located in different places in men and women. They regulate bodily development and maintain reproductive organs in adults.