Body systems 11.4-7 Flashcards
Axon Hillock
where axon is connected to cell body, summation of graded potentials
myelian sheath
fatty insulation that speeds up action potential propagation by stopping ion exchange
oligodendrocytes
central nervous system part of myelian sheath
Schwann cells
Peripheral nervous system part of myelian sheath
Nodes of Ranvier
gaps between myelian sheaths where ion exchange occurs, propagation of action potential occurs here jumping from gap to gap
action potential steps
1) resting: -70 maintained by Na+ and K+ where three Na+ are pumped out and 2 K+ are pumped in
2) Stimulus causes threshold to -55, which causes NA+ ion channels to open allowing NA to flow in and depolarize neuron
3) repolarization of neuron through letting K+ out
4) When potential is less negative that normal threshold, it is hyperpolarizatoin and another potential cannot be fired
5) back to normal
Absolute refractory period
after initiation where another potential cannot be fired no matter how strong the stimulus is
Relative refractory
stronger than normal stimulus can cause another action potential to be fired
Synapse
space between two neurons
synaptic transmission
1) action potential reaches end of presynaptic neuron, causing voltage gated calcium channels to release Ca 2+ into neuron
2) Ca2+ causes synaptic vesicles to fuse and release neurotransmitter into the synapse
3) neurotransmitters bind to ligand-gated ion Chanels in post synaptic neuron, producing graded potentials
4) Graded potentials summate at axon hillock, and action will fire if summation of graded potentials is greater than threshold of neurons
Excitatory postsynaptic potential
graded potential that depolarizes membrane, NA+ ions flow into cell
Inhibitory postsynaptic potential
hyper polarizes membrane, K+ gates open letting K+ flow out, also allows influx of cl-
Microglial cells
macrophages that protect CNS
Macroglial cells (types)
1) Astrocytes- recylce neurotransmitters + provide blood supply to CNS
2) Schwann cells- myelian sheath in PNS
3) Oligodendrocytes- myelian sheath in CNS
4) Satellite cells- provide blood supply to PNS
5) Ependymal cells- produce cerebrospinal fluid which protects CNS
Frontal lobe functions
decision making, long term planning, problem solving, emotions
temporal lobe
speech/language, hearing
Occupital lobe
sight
Parietal lobe
spatial/visual perception, touch, pain, temperature
Thalamus
“relay center” between cerebellum and midbrain
limbic system
next to thalamus, composed of hypothalamus, hippocampus, and amygdala. Responsible for emotion, memory. learning+ motivation
dorsal roots
how signals get sent to spinal cord then to brain
ventral roots
sending signals back out to muscles
Meninges
protect CNS, 3 layers: Dura, arachnoid, Pia “DAP”
Somatic nervous system
voluntary, motor action and sensory input part of PNS. Skeletal muscles
Autonomic
involuntary, sympathies (fight or flight) Parasympathetic(rest+digest)
Ganglion
cluster of nerve bodies in PNS
Sympathetic: short preganglionic nerves and long postganglionic nerves
Parasympathetic: opposite
Cochlea
uses fluids+hairs to convert mechanical signal into neuronal signal known as transduction
Olfactory receptor cells
sense molecules and send them to olfactory cortex which gives us sense of smell
Smooth muscle
Involuntary, not striated, 1 nucleus per cell
cardiac muscle
Involuntary, striated, 1 nucleus per cell
Skeletal muscle
Voluntary, many nuclei per cell, striated
Muscle structure
Muscle, muscle fascicles, muscle fibers, myofibrils
sarcolemma
muscle fibers cell membrane
sarcomeres
functional unit of muscle and shorten to cause contraction
Stimulation of muscle contraction
1) action potential reaches end of neuron axon
2) Acetlycholine is released as neurotransmitter between presynaptic and postsynaptic skeletal muscle at neuromuscular junction
3) Acetylcholine binds to ligand gated ion channels, allowing Na to flow into the cell creating graded potentials
4) graded potential triggers opening of voltage gated ions channels which may produce action potentials on the muscle.
sarcoplasmic reticulum
releases stored calcium cells into sarcoplasm through voltage gated ion Chanels when triggered by depolarization
Troponin
calcium ions bind to this which removes tropomyosin from myosin binding sites on actin, allowing myosin to interact with actin
Cross bridge cycling
1) calcium ions expose myosin binding sites on actin
2) cocked back, high energy myosin head (ADP + P) forms a cross bridge with the actin.
3) myosin head contract and power stroke occurs, bringing myosin her back to low energy, releasing ADP + P.
4) New ATP molecule binds to myosin causing detachment of myosin head from actin filament
5) myosin hydrolyzes ATP to ADP + P and goes back to high energy state
6) sarcoplasmic reticulum pumps Ca back into itself causing trop non to bind back with tropomyosin.
Z lines
end of sarcomeres, acton filaments branch from here
M lines
midpoints were thich myosin filaments branch from
I band
only actin filaments are present
A band
where actin+myosin overlap
H zone
only myosin present
Summation
twitches add up to create a larger overall contraciton
wave summation
depolarization of a motor unit again during a relaxation phase, may cause tetanus
motor unit summation
different motor units simulated at different times to produce intended amount of contraction
endoskeleton
axial- core bones
appendicular
skeleton- limbs
long bones
made of cortical bones+ pockets of cancellous bone
diaphysis
long hollow shaft in center of bone
medullary cavity
within diaphysis+ had red and yellow bone marrow
metaphysis
similar to epiphysis and found between medullary cavity and epiphyseal plates
epiphyseal plate
growth plate between epiphysis and metaphysic, works to lengthen diaphysis through ossification
sesamoid bones
found within tendons to help muscles pull
cortical bone
dense outer layer that supports weight of bodies
osteons
cortical bones functional unit, composed of tiny multi layered cylinders
Haversian canals
tubes that contain blood vessels for nutrient supply
Lamellae
layers of osteon
Lacunae
small spaces between lamellae that hold cells + interconnect through canaliculi
canaliculi
small channels that connect lacunae and Haversian canal
volksmann canals
connect Haversian canals to periosteum which provides nutrients. Interconnects osteons with each other and with periosteum
Osteoprogenitors
immature precursor cells that differentiate into osteoblasts
Osteocytes
live in lacunae in osteons to maintain bone
parathyroid hormone
increases blood Ca by stimulating osteoclasts
Vitamin D
increase blood calcium by raising intestinal calcium absorption
calcitonin
decreases blood calcium, activates osteoblasts
osteoid
organic component of bone containing many proteins such as collagen
hydroxyapatite
inorganic material and component of bone that gives its density and strength
Intramembraneous ossification
bone created directly within fibrous membranes, mainly for flat bones. eventually created cortical bone
endochronal ossification
bone created indirectly through a cartilage model, daily for long bones. Cartilage model calcifies during fetal development
tendons
muscles to bones
ligaments
bone to bone
periosteum
membrane that covers cortical bone with an outer fibrous layer (vascularized) and an inner/ cambium layer (collagen for attachment to cortical bone)
chondroblasts
build cartilage through collagen and elastin
hyaline cartilage
slightly flexible and important in providing support to joints
fibrous cartilage
high rigidity and resists tension
elastic cartilage
highly flex
synarthroses
dense, fibrous joints that don’t move
amphiarthroses
cartilaginous joints that partially move
diarthroses
synovial joints that fully move (hyaline cartilage)
