Stress 101 Module 1 Flashcards
What is neuron?
Brain cells specialized to send electric signals.
S-re of neuron on picture.
What are the parts of neuron?
- Cell body
Contains the nucleus and cellular organelles - Dendrites
Branches from cell body that receive signals - Axon
Extends from cell body to transmit signals to others
What are the kinds of brain cells? How most of brain cells called?
- Neurons vary in size and shape, depending on their location and function.
- Most brain cells aren’t neurons. Most are glial cells that help support the neurons.
How neurons send and receive signals? Define nerves?
Neurons receive signals at dendrites
* If enough signals are received, the neuron sends signals to other neurons.
* Signals are sent down the axon, which can be very long.
* Bundles of axons are called nerves.
How do neurons communicate?
- Neurons do not touch one another
- Neurons communicate across small gaps
Called synapses - Neurons communicate by sending chemical messages
Called neurotransmitters
How occurs the process of synaptic connection?
Neurotransmitters bind to receptors on the receiving neuron (the post-synaptic neuron)
* When binding occurs the neuron becomes either more or less likely to fire.
Neurotransmitters can be
- Excitatory – increase rate of fire.
- Inhibitory – decrease rate of fire.
Neurons can send and receive messages to and from hundreds of other neurons. - A single neuron can excite some neurons while also inhibiting others
What is an action potential and how it’s triggered? What is its strength?
- Neurotransmitters in the synapse can trigger an action potential.
- The action potential is a temporary change in polarity
- The neuron shifts from being negatively charged (-) to being positively charged (+)
- The Action Potentials are “All or Nothing”, which either fires or doesn’t.
- The strength of the action potential is always the same
Describe the process of action potential and its stages
1) Resting potential
* Maintains equilibrium of positive (+) and negative (-) ions inside and outside of the cell.
* At rest, the inside has a negative (-) charge
2) Depolarization
* Ion channels active
* Positive (Na +) ions enter
* Creates net positive (+) charge
3) Repolarization
* Positive (K+) ions get “kicked out”
* Begins return to negative (–) charge
4) Hyperpolarization
* Temporarily too much negative (-) charge
* Unable to fire again until returning to resting potential
Describe the passage of voltage-gated ion channels?
Each ion has specific ion channels to move in or out the cell * Positive ions: Na+ (sodium), K+ (potassium), Ca+ (calcium)
* Negative ions: Cl- (chlorine)
* Additional negative charge from proteins inside the cell
* A resting potential of -70 millivolts maintained by keeping a higher concentration of Na+ outside the cell than inside
* Na+/K+ pumps move 3 Na+ ions outside (out) for 2 K+ ions that move inside (in)
Describe the travel of action potential
What are the types of ion channels?
1) Leak channels
- Open all the time
- Allow ions to move freely in or out of the cell
2) Gated channels
- Open in response to specific signals
- Chemically Gated: open when neurotransmitters bind
- Voltage Gated: open due to change in electric potential
When the action potential occurs?
Action potential occurs when excitatory neurotransmitters open enough chemically gated channels to then cause the voltage-gated channels to open.
An action potential is a rapid rise (depolarization) and fall (repolarization) in voltage or membrane potential across a cellular membrane caused by the opening and closing of ion channels.
Excitatory vs inhibitory neurotransmitters: kinds and function
Neurotransmitters speed up or slow down how neurons fire by binding receptors that activate ion channels
* Excitatory (like glutamate, norepinephrine, dopamine) – open more Na+ channels
* Inhibition (like GABA, serotonin, dopamine) – open more Cl- channels
Chemical Messengers - how neurotransmitters are distributed?
1) The most common neurotransmitters are distributed through the entire brain and nervous system
* Glutamate(Excitatory)
* GABA(inhibitory)
2) Other neurotransmitters used more selectively in connections between different regions
* serotonin (speak between different brain regions)
* dopamine
* acetylcholine
* norepinephrine
Organization and kinds of the Nervous System
1) Central Nervous system: Brain and spinal cord
2) Peripheral nervous system:
1. Somatic (muscles, senses)
** Sensory system (sensations)
** Motor system
2. Autonomic (guts)
* Sympathetic (keep attention)
** “Fight or Flight”
* Parasympathetic
** “Rest and Digest” (relax)
Navigating the brain: parts
Lateral < Medial (to middle) > Lateral (outside)
Slicing the Brain
The Diencephalon contains
First info goes to thalamus and then to other parts of the brain
1) Thalamus
* “Relay station” for sensory information (such as vision, some goes to amygdala)
* Sensory info “sorted and shipped out” from here
2) Hypothalamus (mental cycle and sexual orientation)
* Connected to pituitary gland
* Allows brain to regulate hormones in the body
* Maintains the body’s homeostasis
* Controls activity of autonomic nervous system
What are the major parts of the brain?
1) cerebrum: made up an outer layer, called the cortex, which is responsible for thinking, learning, memory, and emotions.
2) brain stem (or medulla): begins underneath the brain and extends downward until it becomes part of the spinal cord. (It is very important because it handles automatic functions like breathing, heart rate, and wakefulness). Messages from spinal cord and peripheral nervous system enter and exit the brain thru the brain stem.
The reticular activating system:
- the part of the brain stem that responsible for wakefulness.
- screens incoming information
- is responsible for alertness
3) cerebellum
- Helps process sensory information used to maintain balance
- Name means “little brain”
The hypothalamic-pituitary-adrenal axis (HPA)? Its function?
the main stress response system. It is the neuroendocrine link between perceived stress and physiological reactions to stress.
* Hypothalamus releases corticotropin releasing hormone (CRH).
* CRH causes the pituitary to release adrenocorticotropic
hormone (ACTH).
* ACTH in blood causes the adrenal glands to release cortisol.
Describe two pathways of stress response
