Lecture 3 + Textbook ch6 module 4-7 Flashcards
Define Neurons
cells that receive, integrate and transmit information
What are the 2 types of cells the nervous system is comprised of?
neurons and glial cells
Define Glial cells
cells that support neurons, the glue
How do glial cells support neurons?
provide nourishment, remove waste products, and provide insulation around axons
How many neurons are in the human brain?
about 60 billion
The neuron features:
soma, dendrites, axons, myelin sheath, and terminal branches
What % of brain’s total cells are glial cells?
about 90%
Which replaces itself more: neurons or glial cells?
glial cells
Define Dendrites
receives messages from other cells and conducts it towards cell body (soma)
Define Cell Body
the cell’s life-support center
Define Axons
Passes messages away from the cell body to other neurons, muscles, or glands
Define Terminal Branches of Axon
form junctions with other cells
Define Action Potential
electrical signal travelling down the axon
Define Myelin Sheath
covers the axon of some neurons and helps speed neural impulses
What are the 3 main parts of the neuron?
Cell Body, Dendrites, Axons
What does the terminal buttons do?
transmit the messages to thee dendrites of other cells at meeting points synapses
Define Nodes of Ranvier
intervals where myelin is thin or absent
Why is the myelin sheath important?
the insulation protects the axons from accidentally receiving messages from other cells around them
Are all neurons covered in myelin?
no
What is the excitatory signal?
it allows the neuron to fire, the “gas”, causes depolarization
What is the inhibitory signal?
it prevents the neuron from firing, the “brake”, causes hyperpolarization
What charge does neurons “at rest” have?
negative charge
What is resting potential?
positive outside and negative inside state
Define Depolarization
the shift from negative to positive voltage
What happens during the resting stage?
the sodium channels that opened, close in less than a millisecond and the potassium channels + the positively charged potassium items are pumped out of the cell
Define All-or-None Response
the neurons fire or they don’t
Define Synapse
the junction between the terminal button of one neuron (pre-synaptic) and either:
the dendrite of another (post-synaptic)
the membrane of a muscle gland
or a gland
Define Synaptic Cleft
the gap between the terminal button of the pre-synaptic neuron and the cell membrane of the post-synaptic neuron
What are neurotransmitters responsible for?
transmitting info from one neuron to another through the synaptic cleft
Define Receptor Sites
in the post-synaptic neuron where neurotransmitters bind to the neuron
What is the lock and Key Mechanism?
there are different receptor sites for different neurotransmitters, and they fit like a key in a lock
What happens to the excess neurotransmitters?
they either drift away, are broken down by an enzyme, or are re-absorbed by the pre-synaptic neuron
Define Reuptake
When neurotransmitters are reused and recycled for future use
Define Neurotransmitters
the chemicals that are released by terminal buttons to communicate with other neurons across the synaptic cleft
What is Hyperpolarization?
when positive ions flow out and negative ions flow in
Define Agonist
A chemical that increases the action of a neurotransmitter
Define Antagonist
A chemical that opposes/blocks the action of a neurotransmitter
What are some common neurotransmitters?
acetylcholine, dopamine, endorphins, serotonin, norepinephrine, GABA, glutamate
Define Nervous System
the body’s speedy electrochemical communication network, which consists of all nerve cells of CNS and PNS
Define Central Nervous System
comprised of the brain and spinal cord which are the body’s decision-makers
What does the Spinal Cord do?
transmits info between the brain to the rest of the body through the PNS, handles simple reflexes
the brain is 3lbs of…
protein, fat, and fluid
Define Peripheral Nervous System
comprised of the nerves that lie outside the brain and spinal cord
What are the two subareas of PNS?
somatic nervous system and autonomic nervous system
Define Somatic Nervous System
also called skeletal system. Nerves that connect to voluntary skeletal muscles and sensory receptors
The Somatic Nervous System is further subdivided into:
Sensory Neurons, Motor Neurons, and Interneurons
Define Sensory Neurons
Carry information from the body’s tissues and sensory receptors to the CNS
Define Motor Neurons
Carry outgoing information from CNS to the muscles and glands
Define Interneurons
Sensory-motor relay within the CNS
Define Autonomic Nervous System
Nerves that connect to the heart, blood vessels, smooth muscles and glands
Autonomic Nervous System is further subdivided into:
Sympathetic Nervous System and Parasympathetic Nervous System
Define Sympathetic NS
Stimulates energy resources to deal with threatening situations e.g., fight or flight
Define Parasympathetic NS
acts to conserve energy, calms you down
What are the 3 main divisions of vertebrae brains?
Hindbrain, midbrain, and forebrain
Define Hindbrain
contains brainstem structures that direct essential survival functions
Define Midbrain
connects the hindbrain to forebrain, controls some movement and transmit info that enables seeing and hearing
Define Forebrain
manages complex cognitive activities, sensory and associative functions, and voluntary motor activities
Define Brainstem
is central core of brain, beginning where spinal cord swells; responsible for automatic survival functions
Define Medulla
located at the base of the brainstem, controls heartbeat and breathing
Define Pons
Sits above the medulla and helps coordinate movement and controls sleep
Define Cerebellum
the hindbrain’s “little brain” attached to the rear of the brainstem, helps coordinate voluntary movements and balance, enables nonverbal learning and skill memory
What happens when there is damage to the cerebellum?
coordination difficulties
Define Thalamus
located on the top of the brainstem, direct messages to sensory receiving areas in cortex, and transmits replies to cerebellum and medulla
Define Reticular Formation
plays an important role in controlling arousal, and filters information
Define Limbic System
is a doughnut-shaped system of neural structures at the border of the brainstem and cerebrum, associated with emotions
4 Fs of the Limbic System
fight, flight, feeding, and fornication
the limbic system contains…
amygdala, hypothalamus, hippocampus
Define Amygdala
involved in the response of fear and aggression
Define Hypothalamus
regulates body functions like hunger, thirst, body temp. linked to emotion & reward, and the control of the endocrine system and pituitary glands
Define Hippocampus
processes conscious memories, converts short term into long term memory, decreases in size and function with age
What is the Cerebral Cortex?
a thin layer of interconnected neural cells that covers the cerebral hemispheres, body’s ultimate control and info processing centre
The cerebral cortex contains…
20-23 billion nerve cells and 300 trillion synaptic connections
What are the 4 lobes of cerebral cortex?
frontal, temporal, parietal, occipital
Define frontal lobe
receives and coordinates messages from other lobes, motor control, speech production, located right behind the forehead
Define Parietal Lobe
Receives info about pressure, pain, touch and temperature, located on the top, near the back of the head
Define Occipital Lobe
primary visual cortex, input from eyes via optic nerve; output to parietal & temporal lobes, located at the back of the head
Define Temporal Lobe
Primary auditory cortex, memory and some emotion control, input from ears; outputs to limbic system, basal ganglia and brainstem, located almost directly below the parietal lobe
What happens if there is damage to temporal lobe?
inability to store anything in long term memory
Define Motor Cortex
Right hemisphere section controls the body’s left side
Define Somatosensory Cortex
Left hemisphere section receives input from the body’s right side
Define Association Areas
found in all four lobes, responsible for interpreting, integrating and acting on info received and process by sensory info and then linking it with stored memories
Why are Association Areas not involved in primary motor or primary sensory functions?
Association areas are busy with higher mental functions
What happened to Phineas Gage?
an iron rod was pushed through the front of his skull, caused damage to the frontal lobe, changed his personality from mild-mannered and calm to moody and selfish
What does Brain’s Plasticity refer to?
the brain’s ability to modify itself after some types of injury or illness
Define Lateralization
greater localization of function in one hemisphere, but not left vs right hemisphere
Define Corpus Callosum
Mass of neurons that connect the left and right hemisphere, allowing communication between them
What does Splitting the Brain refer to?
a procedure in which two hemispheres of the brain are isolated by cutting the connecting fibers between them
