Unit III - Biological Bases of Behavior Flashcards
Why are psychologists concerned with human biology?
Psychologists from the biological perspective study the links between our biology and our behavior and mental processes.
What is a neuron?
A nerve cell - basic building block of the nervous system
What is the cell body or soma?
Part of the neuron - contains the nucleus, the cell’s life-support center
What are the dendrites?
Bushy, branching extensions
Receive & integrate messages,
Conducting impulses toward cell body
What is the axon?
Attached to the soma,
Neuron extension that passes messages through its branches to other neurons or to muscles or glands.
What is the myelin sheath?
Fatty tissue layer segmentally encasing the axons of some neurons
Increases transmission speed and provides insulation
What is myelin and why is it important?
Babies- no myelinated axons
Development not complete until age 25
Deterioration can lead to motor impairments (e.g. multiple sclerosis)
What are the terminal branches?
Ends of axon containing terminal buttons
Hold synaptic vesicles that store neurotransmitters
What are glial cells?
Cells that support, nourish, and protect neurons
Role in learning, thinking, and memory
Neurons are like…
Glial cells are like
(hint:bee)
Queen bee- can’t perform any tasks
Worker bees- provide nutrients, insulation, guiding neural connections, clean up chemicals
How is a neural impulse generated?
Combined received chemical signals exceed a minimum threshold, neuron fires transmitting an electrical impulse down axon
What is a threshold?
The level of stimulation required to trigger a neural impulse.
Neurotransmitters received by the dendrites build up to initiate the action potential
What is the all-or-none response?
More stimulation does not produce a more intense neural transmission
Neural rxn is all or nothing
Similar to gun, fire or don’t - squeezing trigger does not make bullet go faster
Neural impulses can be…
excitatory or inhibitory
What is an excitatory signal?
Like gas pedal on car
Signals trigger action
What is an inhibitory signal?
Like the brake pedal on car
Signals depress action
When excitatory impulses outnumber the inhibitory impulses,
threshold has been reached and an action potential occurs
What is the resting state of an axon?
Polarized
Outside of axon’s membrane- positively charged sodium (Na+) ions
Inside of membrane- negatively charged proteins and small amount of positively charged (K+) ions
What does it mean that an axon membrane is selectively permeable?
Membrane contains voltage gated ion channels that either open to allow ion exchange or close to prevent ion exchange
What is the first step in an action potential?
first section of semipermeable axon opens its gates once threshold is met
Na+ ions flood in through the channels
Why do Na+ ions rush in?
Since the inside of the membrane is slightly more negative, the Na+ ions try to balance the charge.
This causes a slight depolarization
What is the second step in an action potential?
The depolarization changes the electrical charge of the next part of the axon.
Gates in this second area now open, allowing even more Na+ ions to flow in
When Na+ ions move in, what happens to the K+ ions?
Gates open in first part of axon to allow K+ ions to flow out to repolarizes that section
What is the third step in an action potential?
Sodium/potassium pump continues to depolarize new sections of axons/re-polarize the previous sections
How does impulse move?
The influx of the positive ions is the neural impulse.
The impulse moves down the axon like dominos falling one after the other.
What happens after the action potential moves to the end of the neuron??
Neurons need short breaks
REFRACTORY period- subsequent action potential can’t occur until axon reaches resting state
What is polarization?
the resting state of the neuron, charge is more positive outside the membrane and more negative inside.
What is depolarization?
the action potential; the rushing in and out of positively charged ions
What is repolarization?
the refractory period; the closing of the membrane and reestablishing a more negative charge inside
How do neurons communicate with each other?
The sending neuron releases neurotransmitters across a synapse to the receiving neuron.
What is a neurotransmitter?
Chemical messengers that travel acorss the synapse and bind to the receptor sites on the receiving neuron
What is a synapse?
the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron
What is the synaptic gap/cleft?
Tiny gap at this junction
When an action potential reaches an axon terminal branch,…
it stimulates the release of neurotransmitter molecules which cross the synaptic gap/bind to receptor sites on receiving neuron
Once a neuron receives neurotransmitters from another neuron’s terminal branch,
this will either excite or inhibit a new action potential
What is reuptake?
A neurotransmitter’s reabsorption by the sending neuron
Neurotransmitters have different
neutral pathways
Examples of neural pathways
serotonin pathway
dopamine pathway
Acetylcholine neurotransmitter
Learning and memory
Messenger b/t motor neurons/skeletal muscles
Release causes muscle contractions
Blocked transmission causes paralysis
Dopamine Neurotransmitter
Undersupply of dopamine is linked to Parkinson’s (suffered by Muhammad Ali)
Movement/learning/attention/emotion
Rewards/ addiction/ may lead to schizophrenia when in excess
What are endorphins?
Endogenous morphine
“Morphine within”
Natural opiate like neurotransmitters linked to pain control/pleasure
How do drugs alter neurotransmission ?
Drugs and chemicals from outside the body alter our brain chemistry.
Drugs act as agonists (exciting neuron firing) or as antagonists(inhibiting neuron firing).
How does an agonist work?
An agonist is a drug molecule that increases a neurotransmitter’s action.
How does an antagonist work?
An antagonist is a drug molecule that inhibits or blocks a neurotransmitter’s action.
Antagonists can also work by blocking reuptake
What is the nervous system?
body’s speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems
What are nerves?
bundled axons of many neurons that form neural cables connecting the central nervous system with muscles, glands, and sense organs.
What is an example of nerve?
Optic nerve bundles a million axons into a single cable carrying messages from the eye to the brain
What are the three types of neurons?
sensory (afferent), motor(efferent) and interneurons.
What are sensory neurons?
contain afferent nerve fibers
carry information from the sense organs to the CNS
What are motor neurons?
contain efferent neurons
carry messages from the CNS to the muscles and glands
How is the nervous system divided?
Peripheral
Central
What systems are under the peripheral NS?
Autonomic
Somatic
What is the Central Nervous System (CNS) and what does it do?
Brain and spinal cord.
The CNS is the decision maker responsible for coordinating incoming sensory messages and outgoing motor messages
What is the Peripheral Nervous System (PNS) and what does it do?
Sensory and motor neurons.
The PNS connects the body to the CNS by gathering information from the senses and transmitting messages from the CNS.
What does the somatic part of the PNS do?
controls the body’s skeletal muscles
also called the skeletal nervous system
What does the autonomic part of the PNS do?
controls the glands and the muscles of the internal organs (such as the heart)
operates automatically
What two parts are in the autonomic divsion?
Sympathetic
Parasympathetic
What does the sympathetic nervous system do?
arouses the body, mobilizing its energy
fight, flight or freeze
The gas pedal of a car.
What does the parasympathetic nervous system do?
calms the body, conserving its energy
rest or digest
The brake pedal of a car
The sympathetic nervous system…
HBDSC
accelerates heartbeat raise blood pressure slows digestion raises blood sugar cools the body
The parasympathetic nervous system…
HBDWC
decelerates heartbeat lowers blood pressure stimulates digestion processes waste calms the body
What are the two parts of the CNS?
Brain
Spinal cord
What and how does the brain function?
Comprised of the cortex and subcortical structures carrying out various functions
Nerves arranged into neural networks
Like people grouping in cities
What and how does the spinal cord function?
2-way connection between PNS and brain
Oversees the sensory and motor pathways of reflexes.
What is the first step in a reflex?
Sense receptors in the skin send signals up through the spinal cord via sensory (afferent) neurons.
What is the second step in a reflex?
Interneurons in the spinal cord receive the information from the sensory neurons and send signals back through motor neurons.
What is the third step in a reflex?
Motor (efferent) neurons connect to muscles in the body and direct movement.
How does a simple reflex occur?
A simple reflex … like that to pain… occurs only in the spinal cord before information reaches the brain.
What is the endocrine system?
body’s “slow” chemical communication system
a set of glands that secrete hormones into the bloodstream