NEURAL AND HORMONAL SYSTEMS MODULE 3 Flashcards
Neuron
a nerve cell, the basic building block of the nervous system
new neurons are born and unused neurons wither away
cell body
the part of the neuron that contains the nucleus; the cell’s life support center
axon
the neuron extension that passes messages through its branches to other neurons or to muscles or glands
dendrites
a neuron’s bushy, branch-like extensions that receive and integrate messages, conducting impulses toward the cell body
Myelin sheath
fatty tissue layer that covers the axons of neurons; speeds up transmission
- if the myelin sheath degenerates MS
- communication to muscles slows and loss of muscle control occurs
Glial cells
cells that support, nourish, and protect neurons; may also play a role in learning, thinking, and memory
-if neurons are the queen bee, glial cells are the worker bees
Action potential
a brief electrical charge that travels down an axon; a neural impulse
-which is faster- your brain or a computer?
excitatory
increases a signal; the gas pedal
inhibitory
decreases a signal; the brake pedal
Threshold
the level of stimulation required to trigger a neural impulse
refractory period
a brief resting pause that occurs after a neuron has fired; no actions can occur until the axon returns to its normal state
neurons needs breaks
All-or-none response
a neuron’s reaction of either firing (with a full strength response) or not at all
-increasing stimulation does not increase neural intensity (a gun doesn’t fire harder or faster just because you squeeze the trigger harder)
-intensity of stimulus is determined by number of neurons triggered
Synapse
the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron; tiny gap at this junction is called the synaptic gap
Neurotransmitters
chemical messengers
- neurotransmitters will cross the synaptic gap and fit into receptor sites like a key in a lock
- they will either excite or inhibit the neuron’s readiness to fire
- excess neurotransmitters are broken down by enzymes or reabsorbed by the sending neuron (reuptake)
- SSRIs
Agonist
a molecule that increases a neurotransmitter’s action
opioids (mimics endorphin- pain reduction/ euphoria)
Antagonist
a molecule that inhibits or blocks a neurotransmitter’s action
botox (blocks Ach-paralyzes fascial muscles)
Nervous system
the body’s speedy electrochemical communication network, consisting of all of the nerve cells of the peripheral nervous system (PNS) and the central nervous system (CNS)
Central nervous system (CNS):
the brain and spinal cord; decision maker
Peripheral nervous system (PNS):
the sensory and motor neurons that connect the CNS to the rest of the body; gatherer and transmitter
Nerves
bundled axons that form neural cables connecting the CNS with muscles, glands, and sense organs
Sensory neurons
neurons that carry incoming information from the body’s tissues and sensory receptors to the brain/ spinal cord;
smell
Motor neurons
neurons that carry outgoing information from the brain/ spinal cord to the muscles and glands
turning a steering wheel
Interneurons
neurons within the brain/ spinal cord; communicate internally and process information between the sensory inputs and motor outputs
-this is where most of the complexity lies
billions and billions of interneurons exist (compared to millions of sensory and motor)
Somatic nervous system
controls the body’s skeletal muscles; also called the skeletal nervous system
Autonomic nervous system (ANS):
controls the glands and muscles of the internal organs (such as the heart, lungs, digestions); automatic; has 2 divisions: sympathetic and parasympathetic
sympathetic nervous system
arouses and expends energy
parasympathetic nervous system
calms and conserves energy
Spinal cord
a two-way information highway connecting the PNS and the brain
reflex
a simple, automatic response to a sensory stimulus; knee-jerk response; touching a hot stove
Endocrine system
the body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream
Hormones
chemical messengers that are made by the endocrine glands that travel through the blood and affect other tissues
Fight or flight
the ANS tells the adrenals glands to secrete epinephrine/ norepinephrine
adrenal glands
a pair of endocrine glands that sit just above the kidneys
effects can linger long after threat is gone
Pituitary gland
the master gland; pea sized; located in the core of the brain, controlled by the hypothalamus
directs other glands to release their hormones
