Mod 3 & 4: The Biology of Behavior Flashcards
Neurons
Nerve cells. Communicators of the brain, continually sending and receiving messages in the form of electrochemical signals.
What are the three types of neurons?
Sensory, Motor and Interneurons
Sensory neurons
Carry messages from the body tissues and sensory receptors inward toward the brain and spinal cord for processing. We have a few million of these
Motor Neurons
Carry instructions from the central nervous system to outward to the body’s muscles. We have a few million of these
Interneurons
process sensory input and motor output. We have billions of these
The main structures of neurons
Cell bodies, dendrites, axons (axon terminals), myelin sheaths, glial cells
Cell Body
Houses of the nucleus of the cell, all the cell’s life support functions occur here.
Dendrites
receive information from other neurons. And move it toward the cell body.
Axon
delivers messages from neuron to other neurons, muscles or glands, through its terminal branches
Axon Terminal (aka presynaptic terminal, end foot, terminal branches of axon)
end of axon, forms junctions with other neurons, release neurotransmitters.
May be several feet long through the body
Myelin Sheath
layers of supportive cells which act to insulate axon and speed up the signal.
• as it is laid down (up to age 25) neural efficiency, judgement, and self-control all increase
• if it degenerates multiple sclerosis occurs
Glial Cells
provide nutrients and insulating myelin, guide neural connections and clean up after neurons send messages to each other
Neural Impulse
When stimulated by senses or triggered by chemical response, neurons transmit messages to each other. In response to that neurons fire impulses
Action potential
a brief electrical charge that travels down its axon
-2 to 180 mph – this is still 3 million times slower than electricity through wire
excitatory and inhibitory signals
Some signals are excitatory (like pushing an accelerator) some are inhibitory (like pushing a brake)
• If excitatory minus inhibitory exceeds a minimum intensity (threshold) the combined signals trigger an action potential.
• Increasing the level of stimulation above the threshold will not increase the neural impulses intensity. It’s an all or none response.
Synapses
the junction between the axon tip and the sending neuron and the dendrite or cell body of the receiving junction discovered by Sir Charles Sherrington
synaptic gap or cleft
the gap between the synapses and the dendrite or cell body
neurotransmitters
When action potentials meet the end of the axon it releases the chemical messengers
Within one ten thousandth of a second the neurotransmitter molecules cross the synaptic gap and bind to receptor sites on the receiving neuron. It locks on for a split second and unlocks tiny channels at the receiving site and electrically charged atoms flow in exciting or inhibiting the receiving neurons readiness to fire reuptake occurs the sending neuron reabsorbs the neurotransmitters from the synapsis
Acetylcholine (ACh)
- Enables muscles action, learning and memory
- Is the messenger at every junction between motor neurons and skeletal neurons
- When released to our muscle cell receptors the muscle contract
Endorphins
The brains own naturally produced opiates
endogens [produced within] morphine
Why not just create artificial opiates to intensify the brains ‘feel good’ chemistry?
o When flooded with opiate drugs such as morphine and heroine the brain may stop creating its own natural opiates
o When the drugs are withdrawn the brain has no opiates left leaving you with intense discomfort.
Formed by the brain and spinal cord, the ____ is the body’s decision maker
Central Nervous System (CNS)
The brains neurons cluster into work groups called ____
neural networks
Peripheral Nervous System (PNS)
Responsible for gathering information and transmitting CNS data to other body parts
The two components of the PNS
Somatic Nervous System (skeletal nervous system) & Autonomic nervous system ANS
Somatic Nervous System (skeletal nervous system)
Responsible for all voluntary actions
Autonomic nervous system ANS
Part of the PNS
Controls involuntary or automatic actions such as breathing and heartbeat
Can further be broken down into the sympathetic and parasympathetic nervous systems
Sympathetic Nervous system
Part of the ANS which is a part of the PNS
Arouses and expends engergy
Parasympathetic Nervous system
Part of the ANS which is a part of the PNS
Calms- Conserves energy
If the body is stressed what will the sympathetic nervous system do?
o Increase in heart rate
o Speed up Breathing
o Increase Blood pressure
o Raise Blood sugar levels
The endocrine system glands secrete chemical messengers called what?
Hormones
Hormones
Influence our interest in sex, food and our aggression
Some are chemically identical to neurotransmitters
Tend to outlast the effects of neural messages
Explains why feelings linger beyond our awareness of what upset us
What is the Master Gland and why?
Pituitary Gland can trigger the other glands to release their hormones
The oldest and most innermost region of the brain
The Brainstem
What does the medulla control?
Heartbeat and breathing
Above the medulla is the ___ which helps coordinate movement
Pons.
The ___ is located where the spinal cord swells slightly after entering the skull
Medulla
Thalamus
The topmost part of the brainstem
What does the thalamus do?
o It receives all sense information except for smell, and reroutes it to higher brain regions
o It also receives some replies which it reroutes to the medulla and cerebellum
Reticular formation
Net-like, can be found between the ears, filters incoming stimuli, relays important information, and controls arousal
Cerebellum or “little brain”
o Enables nonverbal learning and memory. Also helps judge time modulate our emotions and discriminate sound and textures, as well as coordinates voluntary movement
The Limbic System controls what
emotion and motivation
What had the amygdala been linked to?
fear and agression
Hypothalamus
• Located just below (hypo) the thalamus
• Controls body maintenance
o Hunger, thirst, body temp, and sexual behavior. Together they help maintain a steady (homeostatic) internal state.
• Monitors your body, secreting hormones when needed
• Olds and Milner placed an electrode on a rats and accidently found a “pleasure center”
o Came to be known as reward centers
o Area of the hypothalamus
o Rats would press the pedals to trigger the stimulation in these areas up to 7000 per hour sometimes until they fainted
o Humans also have pleasure centers. Though not as addictive as rats.
Where is the “pleasure center” located?
The Hypothalamus
Processes conscious memories, people who lose this part of their brain lose the ability to form new memories
Hippocampus
Primitive animals, lower mammals, advanced mammals brain functions.
- -Primitive animals (like sharks): not-so-complex brain primarily regulates basic survival functions
- -Lower mammals (Rodents): more complex brain: enables emotion and greater memory
- -Advanced mammal (humans): a brain that processes more information enables increased foresight as well
Which part of the brain is extremely sensitive to alcohol?
The Cerebellum
The two cerebral hemispheres contributing 85% of the brains weight makes up ___
The Cerebrum
Cerebral Cortex
A thin surface layer of interconnected neural cells. “ultimate control and information processing center” without its wrinkles it would be the size of a large pizza!
The larger cortex of mammals offers larger or smaller capacities for learning and thinking?
Larger.
The 4 lobes of the brain
Frontal lobe- behind the forehead
Parietal lobes- top to the rear
Occipital lobes – at the back of the head
Temporal lobes – just above the ears
Frontal Lobe Location
Behind the Forehead
Parietal Lobe Location
Top to the Rear
Occipital Lobe Location
At the Back of the Head
Temporal Lobe Location
Just Above the Ears
Who discovered the Motor Cortex and why?
Gustav Fritsch and Eduard Hitzig discovered electrical stimulation when applied on an arch-shaped region at the back of the frontal lobe, to parts of animal’s brain made parts of their bodies move. They discovered the Motor Cortex:
Motor Cortex
An area at the rear of the frontal lobes that controls voluntary movement
Sensory Cortex
located at the front of the parietal lobes parallel to and just behind the motor cortex- receives information from the skin senses and from the movement body parts
The more sensitive the body region the larger the sensory cortex area devoted to it.
Areas that are not involved in sensory functions but rather in higher functions such as learning, remembering, thing and speaking are called what?
Association areas
Association Areas in the four lobes
• Frontal lobe
o Enables judgment, planning and processing of new memories
o If damaged may have intact memories and high intelligence but lack scheduling abilities.
o Can also alter personality if damaged.
♣ Phineas Gage
• Parietal Lobes
o Enable mathematical and spatial reasoning
o Einstein had large and unusually shaped parietal lobes
• Right Temporal Lobe (underside)
o Ability to recognize faces
o If this area is destroyed you could still describe facial features, recognize sex, and approximate age but be unable to identify the person
Plasticity
the ability to change or modify itself after damage has occurred, especially during childhood
The wide band of axon fibers connecting the two hemispheres and carrying messages between the two
Corpus Callosum
Split brain
The splitting of the Corpus Callosum and thus the division of the two hemispheres of the brain
