DAT Nervous System, Muscular System, Skeletal System Flashcards
responsibility of nervous system
for coordinating our
sensory and motor functions by transmitting
signals around our body.
where all does the nervous system include
brain, spinal
cord, nerves, neural support cells, and certain
sensory organs (eye, ear).
functional unit of nervous system
neuron
Neuron
consists of several dendrites,
a single branched axon, and cell body
(soma). Neurons are highly specialized,
aren’t able to divide, and are highly
dependent on glucose for chemical
energy.
Axon hillock
where the soma connects
to the axon; action potentials are
generated here
Dendrites
receive information and
transfer it to the cell body
Axon
- transfers impulses away from the
cell body
Myelinated axons appear what color
white
neuronal cell bodies are what color
grey
Glial cells
nervous tissue support cells
that are capable of cell division
Oligodendrocytes
produce myelin
in the central nervous system (CNS)
Schwann cells
produce myelin in
the peripheral nervous system (PNS)
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
Microglia
phagocytes of the
CNS
Ependymal cells
use cilia to
circulate cerebrospinal fluid
Satellite cells
groups of cell
bodies in the PNS that serve as
support cells
Astrocytes
provide physical
support to neurons of the CNS
and maintain the mineral and
nutrient balance
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)
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 what
interneurons
Motor (efferent) neurons
- travel from
the brain and stimulate effectors, which
are target cells that elicit some response
nerve impulse
electrical signal that is
transmitted along a nerve fiber, allowing us to
send signals to perform actions like raising an
arm to catch a ball
The resting membrane potential, the normal
unstimulated state of a neuron, is what?
negative
Steps of Nerve Impulse Transmission
Resting potential, action potential, repolarization, Hyperpolarization, Refractory period,
signal is transmitted across a synapse by…
traveling from the pre-synaptic neuron to the
post-synaptic neuron.
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
Chemical transmission
a unidirectional action
potential that is most typical in animal
cells
Steps of Transmission Across Chemical
Synapse
- Ca2+ gates open, 2. Synaptic vessels release
neurotransmitter, 3. Neurotransmitter binds with
postsynaptic receptors, 4. Postsynaptic membrane is excited or
inhibited, 5. Neurotransmitter is degraded/
recycled/diffused away -
Diameter factor
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
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
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)
Epinephrine, norepinephrine,
dopamine, and serotonin (5HT) -
secreted between neurons of the
CNS
Neuropeptides
short chains of amino
acids and are a diverse group including
substance P and endorphins
Gases
Unlike most neurotransmitters, these
are not stored in vesicles and are
actually synthesized and released on
demand! Example: nitric oxide (NO)
Central Nervous System (CNS)
Consists of the interneurons, brain, and spinal
cord.
Meninges include…
Dura mater, Arachnoid mater, Space between arachnoid and pia
mater, Pia mater
Dura mater
outermost layer; thick,
protects brain and spinal cord, has
vein-like structures to carry blood
from brain back to heart
Arachnoid mater
middle layer with
a spiderweb-like appearance
Space between arachnoid and pia
mater
space filled with
cerebrospinal fluid (CSF) which is
produced by tissue called choroid
plexus in fluid-filled compartments in
the CNS called ventricles
Pia mater
a delicate innermost
membrane covering the brain and
spinal cord
Brain
has outer grey matter (cell bodies)
and inner white matter (axons); consists
of forebrain, midbrain, and hindbrain
Forebrain
- largest and most
important brain region;
cerebrum, which includes the what??
Cerebral cortex, Olfactory bulb, Thalamus, Hypothalamus, Basal ganglia, 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
Midbrain -
relay center for visual
and auditory impulses, and motor
control
Hindbrain
posterior part of the brain
hindbrain contains what?
Cerebellum, Pons, Medulla oblongata, Brainstem,
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
sensory info enters
here
Ventral horn
motor information
exits here
Brain lobes
divides cerebrum
Frontal lobe
responsible for
conscious thought (attention),
initiates voluntary skeletal muscle
movement via motor cortex,
contains olfactory bulb for smell,
Broca’s area for forming speech is
found here, and contains the
prefrontal cortex for decision
making and planning
Parietal lobe
Somatosensation, Proprioception, 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
Temporal lobe
processes and
interprets sounds
Wernicke’s area
understanding speech
Hippocampus
memory
formation
Auditory cortex
processes
auditory information in humans
Occipital lobe
processes and
interprets visual input, responsible
for object recognition, responds to
visual stimuli
Visual association cortex
processes vision
Peripheral Nervous System (PNS)
Consists of the somatic and autonomic branches,
Somatic nervous system
innervates
skeletal muscle and can be voluntary
(raising hand) or involuntary (knee jerk
reflex)
Autonomic nervous system
responsible
for involuntary movement and innervates
cardiac and smooth muscle; divided into
sympathetic and parasympathetic
branches:
Sympathetic branch
responsible for fight or
flight response by doing the following:
a. Increasing blood pressure and
heart rate
b. Ejaculating
c. Generating energy (liver converts
glycogen → glucose)
d. Inhibiting digestion, urination, and
salivary secretion
Parasympathetic
responsible for rest
and digest activities by doing the
following:
a. Lowering heart rate
b. Increasing digestion, relaxation, sexual arousal
Nerves of sympathetic nervous
system -
Preganglionic, postganglionic
Preganglionic sympathetic
originate in and
exit the CNS midway through
the spinal cord and form
synapses in ganglia (with
postganglionic nerves) just
outside the spinal cord; release
acetylcholine
Postganglionic sympathetic
release
epinephrine/norepinephrine
Preganglionic parasympathetic
originate and
exit the CNS from the base of
the brain and upper spinal cord
and form synapses with ganglia
in or near effectors; release
acetylcholine
Postganglionic
release
acetylcholine as well (sometimes
nitric oxide)
Nicotinic Acetylcholine receptors
- found on skeletal
muscle and on postganglionic
nerves at the ganglia
Muscarinic acetylcholine receptors
found on effectors
for the parasympathetic nervous
system
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
Supraorbital nerve
serves structures
surrounding the eyes and scalp
path of vision
cornea, pupil, lense, retina
sclera,
connective tissue layer of the eye
choroid,
vascular layer providing blood and
nutrition to the retina.
Cones
responsible for perceiving high-
intensity illumination and are sensitive to
color
Rods
receptive to low-intensity light;
are important in night vision and do not
perceive color
Fovea
an area with the most dense
concentration of cones and is important
for high acuity vision
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
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
- nearsightedness
Hyperopia
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
contains the auricle/pinna
(what we think of as the ear) and auditory
canal; directs sound into the external
auditory canal → middle ear
Middle ear
amplifies sound; the
tympanic membrane (eardrum) begins in
the middle ear and vibrates at the same
frequency as the incoming sound →
three tiny bones, ossicles, (malleus, incus,
and stapes) → inner ear
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
Protozoans and primitive algae unicellular locomotion
use
cilia or flagella by means of a power
stroke and recovery stroke
Amoeba locomotion
extend pseudopodia, in
which the advancing cell membrane
extends forward
flatworms locomotion
- contain longitudinal
and circular bi-layered muscles that
contract agains the hydrostatic
skeleton
Annelids (segmented worms) locomotion
advance by action of muscles on
hydrostatic skeletons
Skeletal muscle (striated muscle)
are
involved in voluntary movement and
contain fibers with multinucleate cells.
Myofibrils
contain microfilaments
divided into sarcomeres
Sarcomeres
individual contractile
units separated by a border (Z-line)
Sarcoplasm reticulum
stores Ca2+
and surrounds myofibrils
Sarcoplasm
same thing as
cytoplasm, but referred to as
sarcoplasm in muscles
Sarcolemma
plasma membrane of
muscle cells that can propagate
action potentials
sarcomere
the structural unit of a myofibril
in striated muscle and is composed of thin
filaments (made of actin polymers) and thick
filaments (made of the protein myosin)
Z-line
boundary of a single sarcomere
and anchors thin filaments
M-line
center of sarcomere
I-band
region containing thin
filaments (actin) only (on the ends)
H-zone
region containing thick
filaments (myosin) only (in middle)
A-band
area where actin and myosin
overlap
contraction occurs via the
sliding filament model
Sliding Filament Model
- ATP binds to the myosin head, 2. Ca2+ exposes binding sites on actin, 3. Cross bridges between myosin heads
and actin filaments form, 4. ADP + Pi are released, 5. New ATP attaches to the myosin head,
causing cross bridges to unbind
motor unit
a neuron and the muscle fibers it
innervates.
Smaller motor units tend to be activated…
first
Recruitment occurs when
a greater quantity of
muscle fibers are activated by the brain rather
than an increase in frequency of action
potentials that stimulate muscle fiber
contraction.
Simple twitch
response of a single
muscle fiber to brief stimulus; the steps
are the latent period, contraction, and
relaxation
Latent period
time between
stimulation and onset of contraction;
lag
Contraction
contracts following
sliding filament model
Relaxation
- time where muscle
returns to resting position. This
occurs during the absolute
refractory period, where the
muscle is unresponsive to a stimulus
Summation
contractions combine
and become stronger and more
prolonged
Tetanus
continuous sustained
contraction where a muscle cannot
relax
Tonus
state of partial contraction
where the muscle is never completely
relaxed
Sub-threshold stimuli
no motor units
respond
Threshold
one motor unit responds
Sub-maximal
- an increasing number of
motor units respond
Type I muscle fiber
Slow twitch
ii. Lots of myoglobin
iii. Lots of mitochondria
iv. Aerobic endurance
Appear red
vi. Small diameter
Type IIA muscle siber
Fast twitch
ii. Lots of myoglobin
iii. Less endurance than type I
iv. Appear reddish pink
v. Intermediate in diameter
Type IIB muscle fiber
Fast twitch
ii. Low myoglobin - use glycolysis
(primarily use anaerobic)
iii. Lots of glycogen - generates power
iv. Split ATP at a fast rate
v. Fastest to fatigue
vi. Appear white
vii. Large diameter
Single-unit smooth muscle
visceral; connected by gap
junctions, contract as a single unit
(found in stomach, uterus, and urinary
bladder)
Multi-unit
each fiber is directly
attached to the neuron; can contract
independently (found in iris and
bronchioles)
Cardiac Muscle
Has a striated appearance due to sarcomeres,
has one or two central nuclei, has cells separated
by intercalated discs that have gap junctions to
allow action potentials to chain flow via electrical
synapse, contract involuntarily, and have lots of
mitochondria. Cardiac muscle is not connected
to bone, rather it forms a net that contracts
upon itself and grows via hypertrophy.
Exoskeleton
- a hard covering on the
outer surface
Endoskeleton
- the vertebrate skeleton is
comprised of an internal skeleton under
soft tissue. The two major components
are cartilage and bone:
Cartilage
an avascular connective
tissue that is soft and flexible, and
can be found in the ear, nose,
larynx, trachea, and joints
3 types of cartilage
hyaline
(most common, reduces friction
and absorbs shock in joints),
fibrocartilage, and elastic
Development cartilage
arises from
mesenchyme tissue that
differentiates into chondrocytes.
Collagen
present in tissue as a
triple helix with special amino
acids hydroxyproline and
hydroxylysine, ground
substance, and elastin fibers
cartilage Composition
cartilage is
composed primarily of collagen
fibers embedded in chondroitin
sulfate, and receives nutrients
via diffusion
cartilage surroundings
- cartilage is
surrounded by a dense fibrous
connective tissue called
perichondrium
Bone
living connective tissue that is
hard and strong while also elastic and
lightweight
bone Functions
support soft tissue,
protect internal organs, assist in
body movement, mineral storage,
blood cell production, and energy
storage in the form of adipose
cells in bone marrow
bone types
mature or immatire
Axial skeleton
basic framework of the
skeleton that includes the skull, vertebral
column, and rib cage
Appendicular skeleton
bones of
appendages, pectoral and pelvic girdles,
and everything else that isn’t in the axial
skeleton
Sutures
immoveable joins that hold
together the bones of the skull
Moveable joints
bones that move
relative to each other
Ligaments
- bone to bone
connectors that strengthen joints
Tendons
dense connective tissue
that connect muscle to bone and
bend skeleton at moveable joints
Origin
point of attachment of
muscle to stationary bone
Insertion
- point of attachment
of muscle to bone that moves
Extension
straightening of
joint
Flexion
bending of joint
Foramen
- an opening in the
bone that allows for the passage
of nerves (foramen magnum in
the skull allows for the passage
of the spinal cord)
Osteoarthritis
the cartilage
that covers the bone ends of
freely moveable joints begins to
wear away due to aging
Rheumatoid arthritis
a
degenerative cartilage disorder
with a genetic basis
Fibrous joint
connects bones without
allowing any movement (e.g., skull,
pelvis, and vertebrae)
Cartilaginous joint
bones are attached by
cartilage and allow little movement (e.g.,
spine and ribs)
Synovial joint
most common type of joint
that allows for much more movement as
it is filled with synovial fluid that acts as a
lubricant
Osteoprogenitor/osteogenic bone cells
cells
that are part of the mesenchymal stem
cell lineage that differentiate into
osteoblasts
Osteoblasts
secrete collagen and
organic compounds upon which bone is
formed.
Osteocytes
- are incapable of mitosis
and exchange nutrients and waste
material with the blood
Osteoclasts
- resorb (destroy) bone
matrix and release minerals back to the
blood.
Compact bone
highly organized,
dense bone that doesn’t appear to have
cavities from outside.
Haversian canals
osteoclasts
burrow tunnels that form these
canals
Lamellae
concentric rings
Lacunae
osteocytes trapped
between the lamellae reside in a
space called the lacunae
Volkmann’s canals
the Haversian
canal contains nerves, blood vessels,
and lymph vessels, which are
connected by Volkmann’s canals
Osteon
the entire system of
lamellae + Haversian canals
Medullary cavity
- compact bone
surrounds the medullary cavity which
is filled with yellow bone marrow that
contains adipose cells for fat storage
Spongy (cancellous) bone
less
dense bone that consists of an
interconnecting lattice of bony spicules
called trabeculae.
Long bone
typically has a long shaft
(diaphysis) and two ends, each
composed of a metaphysis and
epiphysis.
Endochrondral ossification
cartilage
turns into bone
Intramembranous ossification
undifferentiated connective tissue is
replaced by bone
Osteoporosis
causes bone density to
decrease, and the bone becomes easier
to break and fracture.
