Nervous system Flashcards
Bootcamp + booster
neuron
is the most basic unit of the nervous system.
-contains three parts: the soma, Dendrites, and the axon
Soma
Cell body
Dendrites
receive information and
transfer it to the cell body
Axon
sends signals out
Axon hillock
where the soma connects
to the axon; action potentials are generated here
Glial cells
nervous tissue support cells
that are capable of cell division
Oligodendrocytes
produce myelin sheath in the central nervous system (CNS)
Schwann cell
produce myelin sheath in the peripheral nervous system (PNS)
Mnemonic: COPS
CO: central nervous system (CNS)/Oligodendrocytes
PS: peripheral nervous system (PNS)/Schwann cell
Myelin sheath
fatty sheaths that act as insulators and are separated by Nodes of Ranvier that allow the action potential to travel continuously down the axon, jumping from node to node, a process known as saltatory conduction, that speeds up the impulse
saltatory conduction
are separated by Nodes of Ranvier that allow the action potential to travel continuously down the axon, jumping from node to node
Nodes of Ranvier
gaps between myelin sheaths where ion exchange occurs.
Microglial
- phagocytes of the CNS
- are macrophages that protect the central nervous system (CNS).
Ependymal cells
use cilia to circulate cerebrospinal fluid, which cushions the CNS
Satellite cell
groups of cell bodies in the PNS that serve as support cells
Sensory (afferent) neurons
receive stimulus from the environment and send the stimulus to the brain for processing (e.g., neurons in the retina of the eye)
- send signals to the spinal cord and subsequently the brain through dorsal roots.
Astrocytes
provide physical support to neurons of the CNS and maintain the mineral and
nutrient balance
- form the blood-brain barrier
Association (interneuron) neurons
located in the spinal cord and brain; receive impulses from sensory neurons and send impulses to motor neurons.
- 99% of nerves are interneurons
- Are found in reflex arcs but some do not require an interneuron
Motor (efferent) neurons
send signals back out to the muscles through ventral roots.
- May stimulate muscles, sweat glands, or cells in the stomach to secrete gastrin
Electrical transmission
a bidirectional action potential that travels along membranes of gap junctions; is less common in the body, fast, and found in cardiac and visceral smooth muscle
Steps of Nerve Impulse Transmission
- Resting potential
- Action potential
- Repolarization
- Hyperpolarization
- Refractory period: Absolute refractory period, and Relative refractory period
Chemical transmission
a unidirectional action potential that is most typical in animal cells
synapse
is the space between two neurons.
presynaptic
neuron sends the signal and releases neurotransmitters into the synapse
postsynaptic
neuron receives the signal by interacting with the released neurotransmitters.
Steps of Transmission Across Chemical Synapse
- Ca2+ gates open
- Synaptic vessels release
neurotransmitter - Neurotransmitter binds with
postsynaptic receptors - Postsynaptic membrane is excited or inhibited: Excitatory postsynaptic potential (EPSP) and Inhibitory postsynaptic potential (IPSP)
- Neurotransmitter is degraded/recycled/diffused away
Diameter
greater diameter allows an
impulse to propagate faster since a larger diameter results in a less resistance to the flow of ions (think of passing water
through a large pipe vs. a small one)
Myelination
heavily myelinated axons
allow impulses to propagate faster since Na+ ions can’t leak out, thereby driving saltatory conduction to occur faster
excitatory postsynaptic potential (EPSP)
(EPSP) is a graded potential that depolarizes the membrane.
In an EPSP, excitatory neurotransmitters cause Na+
ion gates to open and let Na+ ions flow into the cell.
inhibitory postsynaptic potential (IPSP)
is a graded potential that hyperpolarizes the membrane. Inhibitory neurotransmitters cause K+ ion gates to open and let K+ ions flow out of the cell. Another IPSP type allows influx of Cl- ,allowing negative Cl- ions in.
Acetylcholine (Ach)
secreted at neuromuscular junctions and cause muscle contraction or relaxation
Glutamate
neurotransmitter at the
neuromuscular junction in
invertebrates, and is the most
common CNS neurotransmitter in vertebrates
types of Amino acids neurotransmitters
Glutamate, gamma aminobutyric Acid (GABA), and Glycine
Gamma aminobutyric acid (GABA)
inhibitory neurotransmitter among brain neurons
Glycine
inhibitory neurotransmitter
among synapses of the CNS outside the brain
Amino acid derived (biogenic amines) Neurotransmitters
Epinephrine, norepinephrine,
dopamine, and serotonin (5HT) -
secreted between neurons of the CNS
- Epinephrine/norepinephrine act in the sympathetic nervous
system and are released from
post ganglionic nerves
Gases neurotransmitters
Unlike most neurotransmitters, these are not stored in vesicles and are actually synthesized and released on demand! Example: nitric oxide (NO)
Neuropeptides neurotransmitters
short chains of amino acids and are a diverse group including substance P and endorphins
central nervous system (CNS)
is composed of the brain and spinal cord.
peripheral nervous system (PNS)
is composed of nerves branching off the CNS.
what three areas can the brain divide to during embryonic development?
Forebrain, Midbrain and Hindbrain
Forebrain
largest and most
important brain region; contains the
cerebrum, which includes the
following: Cerebral Cortex, Olfactory blub, thalamus, hypothalamus, Basal ganglia, adn Hippocampus
Cerebral Cortex
processes sensory input, important for perception, memory, voluntary movement, and learning
Olfactory bulb
smell
Thalamus
relays sensory information between spinal cord and cerebral cortex
Hypothalamus
responsible for visceral function such as water balance, blood pressure regulation, temperature regulation, hunger, thirst, sex drive, circadian rhythms — circadian rhythms coordinated by suprachiasmatic nucleus
Basal ganglia
centers for planning/learning movement sequences
Hippocampus
memory consolidation and spatial navigation
Hindbrain
posterior part of the
brain that contains the following: Cerebellum, pons, Medulla oblongata, Brainstem
Midbrain
relay center for visual and auditory impulses, and motor control
Cerebellum
maintains balance, hand-eye coordination, timing of rapid movements, and motor skills
Pons
relay center to allow communication between the
cortex and cerebellum
Medulla oblongata
regulates breathing, heart rate, and gastrointestinal activity
Brainstem
consists of the midbrain, medulla oblongata, and
pons; connects the cerebrum with the spinal cord and is part of the reticular formation, which is a network of neurons within the brainstem that regulates sleep and arousal
Spinal cord
a bundle of nerves (does not include the bony spine/ vertebral column) with the outer area of the cord consisting of white matter and the inner consisting of gray matter;
contains two horns: Dorsal horn Ventral horn
Dorsal horn
sensory info enters here
Ventral horn
motor information
exits here
Brain lobes
the cerebrum, the largest part of the brain with two hemispheres and connected by the corpus callosum (thick nerve bundle) is divided by lobes: Frontal lobe, Temporal lobe, occipital lobe, and parietal lobe
temporal lobe
- known for speech and
hearing. - also the location for: Wernickes area, Hippocampus and Auditory cortex
Wernickes area
understanding speech
Hippocampus
memory formation
Auditory Cortex
processes auditor information in humans
Parietal lobe
contains the sensory
areas: Somatosensation, proprioception, and somatosensory cortex
Somatosensation
temperature, touch, pressure,
and pain
Proprioception
orientation of body parts in space
Somatosensory cortex
receives and processes sensory
information from entire body
Frontal lobe
known for higher function
processes such as decision making, problem solving, attention and concentration.
Occipital lobe
known for vision.
contains: Visual association cortex
Visual association cortex
processes vision
Amygdala
Responsible for the emotional
reaction to certain scents.
limbic system
thalamus, hypothalamus, hippocampus, and amygdala. It
is responsible for emotion, memory, learning, and motivation.
meninges
protect the CNS and have three
layers: Dura Mater, arachnoid, and pia mater
Types of Sensory Receptors
- Mechanoreceptors
- Thermoreceptors
- nociceptors
- Electromagnetic Receptors
- Chemoreceptors
Mechanoreceptors
touch
Thermoreceptors
temperature
Nociceptors
pain
Electromagnetic receptors
light
Chemoreceptors
taste, smell, blood
chemistry
Vagus nerve
extends from medulla oblongata and innervates parts of the heart, lungs, stomach, intestines, and liver
Sciatic nerve
innervates lower limbs and pelvis
Abducens nerve
serves the somatic muscles surrounding the eyes
Path of Vision
Cornea (focuses light) → pupil (diameter controlled by the pigmented iris) → lens
(thickness controlled by ciliary muscles; responsible for focusing images) → retina
(light sensitive cells)
Supraorbital nerve
serves structures surrounding the eyes and scalp
Cornea
focuses light and protects the eye.
Pupil
- controls how much light enters the eye.
Lens
focuses images on retina.
Retina
back of the eye that has
photoreceptors (rods + cones).
Rods
function at low levels of light
and are responsible for low-light perception.
Cones
function at high levels of
light and are responsible for color perception.
Fovea
highest concentration of
photoreceptors in the retina and responsible
Iris
controls the size of the pupil.
Amacrine and bipolar cells
take information from rods and cones, transmitting the information to ganglion cells of the optic nerve fibers.
Optic nerve
bundle of axons that transmits
visual information to the brain.
Optic disk
the blind spot of the eye, where
the optic nerve passes through to reach the brain.
Sclera
protective connective tissue that
surrounds the eye, the “white part” of the eye.
Choroid
vascular connective tissue.
Vitreous humor
jelly-like liquid between the lens and retina that maintains eye shape and has optical properties; makes up most of the eye volume
- inside the eye
Aqueous humor
watery liquid that fills anterior chamber between the lens and cornea; the eye produces this in order to maintain intraocular pressure and provide nutrients to the avascular ocular tissues
Myopia
eye disorder: nearsightedness
Hyperopia
eye disorder: farsightedness
Astigmatism
irregularly shaped
cornea
Cataracts
lens becomes opaque and
light cannot enter
Glaucoma
an increase in pressure of
the eye due to blocking of outflow of aqueous humor
Outer ear
takes in sound waves, and the
tympanic membrane transfers the sound from outer ear to middle ear.
Middle ear
- is composed of three bony
ossicles the malleus, incus, & stapes. - The ossicles transfer vibrations through the middle ear and amplify the signal.
- The stapes transfers the vibrations from the middle to the inner ear via the oval window.
Inner ear
waves move through the
cochlea (vibration of ossicles exert pressure on the fluid). As the wave moves through alternating pressures, motion is
creating along the basilar membrane. This movement is detected by hair cells (not actual hair cells, but specialized stereocilia cells) of the organ of Corti → transduced neural signal → action potential
transduction.
The cochlea uses fluid and hairs to convert the mechanical signal into a neuronal signal
semicircular canal
has fluid and hairs just like the cochlea but gives information about the person’s movement. It is also the reason we get dizzy.
the tongue has Five taste receptor cells
- sensing salty, sweet, bitter, sour, and umami.
- Taste information is sent to the thalamus and subsequently the gustatory cortex.
