Neuro Review Flashcards
Neuro Review
What is a Nervous System
Because we are not a plant, we are animals. We use the nervous system to process information about the environment and then respond with behavior. We do it with electricity.
Neuron
Brain cells are specialized to send electric signals.
Cell Body
Contains the nucleus and cellular organelles.
Dendrite
Branches from the cell body that receive signals.
Axon
Extension of the cell body to transmit signals to others.
Glial Cells
Most brain cells are not neurons but are glial cells. Glial cells help support neurons.
Where do neurons receive signals from?
Received at the dendrites and if enough signals are received, the neuron will send signals to other neurons.
Where are the signals sent down?
They are sent down the axon. Axons can be very long.
What are bundles of axons?
Nerves.
How do Neurons Communicate?
They communicate through the synapses, which are small gaps. They communicate by sending chemical messages called neurotransmitters.
What do neurotransmitters bind to?
They bind to receptors on the receiving neuron which is called the post-synaptic neuron.
Neurotransmitters can be …?
Excitatory- increase the rate of fire
Inhibitory- decrease the rate of fire
How do chemical messages turn into electric signals?
The action potential
How is an action potential triggered?
It is triggered by neurotransmitters in the synapse.
Action Potential
It is a temporary change in polarity. The neuron goes from being negatively charged to being positively charged.
Action potentials are “All or Nothing”- it either fires or doesn’t. The strength of the action potential is always the same.
What is the firs step of Action Potential?
Resting Potential. Maintaining equilibrium of positive and negative ions inside the outside of the cell. At rest, the inside has negative charge.
What is the second step of Action Potential?
Depolarization. Ion channels are active. Positive ions enter. Net charge becomes positive.
What is the third step of Action Potential?
Repolarization. Positive ions get kicked out and return to being negatively charged.
What is the 4th step of Action Potential?
Hyperpolarization. Temporarily too much negative charge. Unable to fire again until returning to resting potential.
Ion Channels
Each ion has specific ion channels to move in or out of the cell.
Positive ions
Sodium(Na+)
Potassium(K+)
Calcium(Ca+)
Negative Ions
Chlorine(Cl-)
Na+/K+ pumps
3Na+ ions move outside for every 2K+ move inside
Resting Potential
-70 millivolts maintained by keeping a higher concentration of Na+ outside the cell than inside.
Leak Channels
Always open
allow ions to move freely in or out of the cell
Gated Channels
open in response to specific channels. Two types, chemically gated and voltage gated.
Chemically gated
open when neurotransmitters bind
Voltage-Gated
open due to a change in electric potential
When does an Action Potential occur?
Excitatory neurotransmitters open enough chemically gated channels to then cause voltage-gated channels to open. Sodium (Na+) rushes in to depolarize the axon.
Excitatory Neurotransmitters
Glutamate
Norepinephrine
Dopamine
Open more Na+ channels
Inhibitory Neurotransmitters
Serotonin
Dopamine
GABA
Open more Cl- channels
What are the most common neurotransmitters through the brain and the nervous system?
Glutamate (Excitatory) and GABA (Inhibitory)
Which neurotransmitters create specific “circuits between brain regions?
Serotonin
Dopamine
Norepinephrine
Whats the difference between a neurotransmitter and a hormone?
Neurotransmitters are chemical messages that allow communication between neurons.
Hormones are chemical messages that allow communication between different brain and body regions.
What are hormones produced by?
They are produced by different endocrine glands:
pituitary gland
pineal gland
adrenal gland
ovaries and testes
what are parts of the Nervous System?
Central Nervous System and Peripheral Nervous System.
Central Nervous System
Brain and the spinal cord.
Peripheral Nervous System
Autonomic(guts) and Somatic(senses, muscles) System.The autonomic system has two parts: sympathetic and parasympathetic.
Sympathetic Nervous System
“Fight or Flight”
Parasympathetic Nervous System
“Rest and Digest”
Grey Matter
This is where cell bodies of neurons are most concentrated and where the “processing happens”. A lot of bodies are working.
White Matter
This is where neurons are most concentrated and it connects the different areas of the brain. They are white because of the fat (myelin). They send stuff from city to city.
Cerebrum
Cerebal Cortex which is the wrinkly outer area, is relatively thin and has 4 lobes. The frontal, parietal, occipital, and temporal lobes.
Hippocampus
Involved in forming long term memory.
Amygdala
Involved in emotional processing
Salience Detector
Basal Ganglia
Involved in coordinating voluntary movement.
What does the Diencephalon contain?
It contains that the Thalamus which is the relay station for sensory info. The information gets “sorted and shipped” out of here.
It also contains the Hypothalamus. It is connected to the pituitary gland, allows brain to regulate hormones in the body, maintains the body’s homeostasis, and controls activity of an autonomic nervous system.
Cerebellum
Helps process sensory information used to maintain balance. Name means “little brain”.
Reticular Activating System (RAS)
screens incoming information, is responsible for alertness.
Brain Stem or Medulla
Messages from the spinal cord and the peripheral nervous system enter and exit from here.
How does the Nervous System Respond to Stress?
The hypothalamus responds by triggering a stress response.
What are the two pathways for a stress response?
The activation of the sympathetic nervous system so “fight or flight” or the activation of the hypothalamic-pituitary-adrenal axis (HPA).
What is the pathway for the sympathetic nervous system?
Hypothalamus -> sympathetic nervous system->adrenal medulla(inner part of the adrenal gland)-> secretes epinephrine and norepinephrine.
What is the pathway for HPA Axis?
Hypothalamus ->Pituitary ->Adrenal Cortex(outer part of the adrenal gland->secretes cortisol.
The HPA Axis
The hypothalamus release corticotropin-releasing hormone (CRH)
CRH causes the pituitary to release adrenocorticotropic hormone (ACTH)
ACTH in blood causes the adrenal gland to release cortisol.
Why are there two different types of stress responses?
Activation of the “flight or fight” response is associated with adrenaline(epinephrine) and useful for fast responses to immediate threats.
Activation of the HPA allows for a sustained stress response. Cortisol regulates metabolism and immune functioning.
