3.2 nervous system Flashcards
structure of neurons
- soma
- dendrites
- axon
- myelin sheath
- axon terminals
neurons job is to fire or not to fire
-firing decreses the chance the adjacent neurons will fire
soma
cell body
houses cell nuceleus
neurons receive messages from other neurons
dendrites
-tiny branches projecting from cell body
as dendrites recieve messages
they send them to the rest of the cells which travel to the base of the cell body called axon hillock with enough stimulation chemical reactions happen here and flows through the rest of the neuron to the axon
axon
when the chemical reaction reaches the end of the axon they reach the axon terminals which are little bulbs filled with molecules called neurotransmitters, activity reaching the axon terminals will stimulate the release of neurotransmitters which react with the dendrites of other neurons
diff types of neurons
motor- send messages from brain down spinal cord to limbs to muscles
sensory-receive neurons from the senses, and deliver messages to the brain for farther processing, pressure signals, or pain
glial cells
responsible for maintenance activities
-ex activating immune response, facilitate neurons
10* the amount of neurons
-to coat neurons that are responsible for sending rapid messages throughout the brain
-they coat the axon in myelin (insulates axons so that the activity travels much faster)
M S
is a debilitating neurological disorder that produces a range of symptoms
-happens because of lack of myelin
neural firing
- resting potential (not firing) (-vely charged)
- positively charged ions rush into the cell during an action potential
- after the nerve has fired, the positively charged ions are pumped back out of the cell
electrostatic gradient
the inside and outside of the neuron have different charges
concentration gradient
there are different types of ions dominating the inside vs.outside of the neuron
-thee imbalances keep the neuron in a state of tension
when stimulated, a neuron…
ion channels open and positive ions rush in and may result in the neuron firing
AKA as generating an action potential
back to resting potential the +ve ions are pumped out
hyper polarization occurs and the neuron is more negatively charged than before the action potential
-this means that the neuron is briefly unable to fire, which is a phase called, the refractory period
once the action potential reaches an axon terminal is stimulates a release of neural transmitters into a gap b/w the axon terminal and of the firing neuron and the dendrite of an adjacent neuron
gap is called the synapse
presynaptic sends the message
post synaptic receives messages
postsynapitic cell has special receptors for
receiving neurons
excitatory neurotransmitters
increase the chance that the postsynaptic neuron will fire by causing the charge inside the neuron to be less negative
inhibitory neurotransmitters
decrease the chance that the postsynaptic neuron will fire by causing the charge inside the neuron to be more negative
all or non principle
a neuron either generates an action potential or doesn’t generate one, but the magnitude of the action potential is the same every time
a neuron can represent higher intensity stimulation by firing more…
frequently over time rather than how strongly they fire each time
synaptic cleft
reuptake
neurotransmitters get reabsorbed into the axon terminal
common neurotransmitters
glutamate-responsible for brain functions (excitatory)
GABA-inhibitory for sleep, reducing arousal
acetylcholine-control voluntary movement
drug effects on neural activity
agonist-stimulate receptor sites for a particular neurotransmittor
-increase stimulation for post synaptic neurons
- bind to receptor
antagonist-block receptor
-prevent production
(look up direct and indirect)
the endocrine system
hormones are secreted from structures called endocrine glands and enter the blood stream
-delivers hormones to modify physiological processes and maintaining body homeostasis
hypthatlamus is the control system in the endocrine system
brain structure that delivers messages about out biological needs to the pituitary gland
pituitary gland
brain structure that releases hormones and stimulates the production of hormones by the other glands that form the endocrine system
arousal glands
stimulates the production of hormones, such as cortisol and epinephrin,that generate arousal responses
pituitary glands also release endorphins
stimulate pleasure centers in the brain and inhibit signals of pain and displeasure
central nervous system
brain
spinal cord
peripheral nervous system
somatic nervous stystem
autonomic nervous system
somatic nervous system
consists of nerves that control the muscles and others that receive signals from sensory organs
autonomic nervous system
consists of the sympathetic nervous system and the parasympathetic nervous system
sympathetic nervous system
generates heightened arousal to prepare the body to respond to threats
parasympathetic nervous stystem
maintains balance in body systems when there is no need to respond to a threat and suppresses arousal responses after a state of heightened arousal
cells that form structure of brains
thoughts actions and feelings and life sustaining functions rely on the function of neurons
