late night finds AUG 8th Flashcards
glial cells
cells that support the neurons
- structurally and support - astrocytes (BBB), microglia (phagocytic), oligodendrocytes (produce mylein), ependymal ( produce spinal fluid)
potassium equilibrium in and out of the cell?
140mM inside and 4mM outside
so due to concentration gradient K leaks out, but then bc inside is negative, K+ is also pulled in —> this finds a equilibrium so overall no net movement
equilibrium potential of potassium
-90mV (negative bc + ion is leaving)
equilibrium potential of sodium
12mM inside and 145mM outside so concentration leaks Na into the cell (positive ion inside) —> 60mV
net resting potencial is
70mV`
two types of summation
temporal (one neuron) and spatial (many neurons)
temporal summation
several from one neuron over time
spatial summation
several impulses from many different neurons
after threshold is met what ion flows in
Na+ influx
after action potencial isreached what repolarizes it
K+ flows out
what casues sodium to go into the cell if threshold is reached
strong electrochemcal gradient - voltage gated channels open
- electrical - inside is more negative
- chemical - flows down concentration gradient ( there is less sodium inside the cell)
impulse propagation
when an action potencial travels down anaxon
if an axon is wider what is the resulting impulse propagation speed?
it is faster!! bc greater cross-sectional area means less resitence
does length or area affect impulse propagation speed more sigificantly?
area! bigger area= faster impulse
longer length= higher resistence= slower conduction
why does myelien speed up transduction
bc it insulates the axons so well to prevent dissapation of electric energy- so well that the membrane is only permeable at nodes de ravier- thus signal hops = saltatory conduction
incereased intensity of stimuli results in ?
increase f of firing
whats the dif between electrical and chemical transmission
electrical is down a neuron in AP and chemical is across a synapse - with NT
how at NT released
when AP reaches, voltage-gated Ca open and let in Ca- triggers release of vesicles- eocytosis
spinal cord is protected with
vertebral column
spinal crd divided into ( from top to bottom)
cervical, thoracic, lumbar, sacral
dorsal root ganglia
contains the cell bodies of sensory neurons - in the spinal cord - so central NS
- pain, mechanical stim, first order neurons, reflex arch
- The term ‘ganglion’ means a collection of neuronal cell bodies present in the peripheral nervous system. A ganglion consists of cell bodies of neurons present in the peripheral parts of the body. Hence, a ganglion is a part of the peripheral nervous system.
- One of the several types of ganglia present in the peripheral nervous system is dorsal root ganglion.
somatic NS
joints, skin and muscle- sensory and motor neurons/opposite of autonomic
the main difference between to somatic and the autonomic NS
is that the autonomic NS contains two neurons and a synapse in the peripheral part
- first is the preganglionic neuron (soma is in CNS)
- second is postganglionic
but inthe somatic, motor neurons go directly from spinal cord to muscle without synapsing
which system has 2 neurons in PNS
the autonomic NS