Chapter 11.4 - Nervous System Flashcards
soma
cell body of the neuron, contains nucleus
dendrites
receive signals from previous neurons
Axon
part of the neuron that sends signals to the axon terminal and passed onto next neuron
Axon hillock
connects axon to cell body, summated graded potentials
myelin sheaths are formed by ____ in the CNS
oligodendrocytes
myelin sheaths are formed by ___ in the PNS
Schwann cells
how does myelin sheath allow action potentials to travel faster down the axon?
insulated the axon from undergoing ion exchange, can only occur at nodes of ranvier
saltatory propagation/conduction
action potential jumps from one node of ranvier to the next
When a neuron is stimulated, it is ____ and the membrane becomes ___ ____
depolarized; less negative
When a neuron is stimulated, __ ___ ___ are opened
Na+ gated channels
When the threshold potential is reached,:
more Na+ gated channels open, membrane potential becomes more positive creating action potential
Once the membrane potential reaches its max potential:
the neuron will repolarize
How does neuron repolarize?
K⁺ gated channels open up, causing K⁺ outflow out of the neuron
Hyperpolarization
Membrane potential goes lower than resting state, makes it more challening for another AP to fire
refractory period can be ___ or ___
absolute or relative
Absolute refractory period
a second stimulus cannot generate another action potential no matter how powerful it is. Na+ gated channels remain inactivated
relative refractory period
sufficiently powerful stimulus can cause an action potential to occur - voltage gated sodium channels are no longer inactivated, but the neuron is still hyperpolarized
When an AP reached the end of the presynaptic axon: (4)
- voltage gated calcium channels open
- Ca²⁺ ions to flow into the presynaptic neuron
- triggers synaptic vesicles to fuse with the membrane
- via exocytosis release the neurotransmitters they contain into the synaptic cleft
EPSPs
generated by excitatory nt’s; cause NA+ gated gates to open, neuron fires AP
IPSPs
generated by inhibitory neurotransmitters; cause K⁺ ion gates to open, which results in a K⁺ outflow, more hyperpolarized, harder to fire AP
EPSPs and IPSPs are:
graded potentials
True or false: graded potentials always cause AP to fire
false - they vary in magnitude.
an action potential will fire down the axon if:
the sum of EPSPs and IPSPs is higher (less negative) than the threshold potential
APs are:
all or nothing (either it fires or not at all)
which amino acids act as NTs
glutamate, GABA, glycine
glutamate
main excitatory NT of the CNS, most abundant in the vertebrate nervous system; NT of neuromuscular junction in invertebrates
GABA
inhibitory NT of the brain
glycine
inhibitory NT of the CNS (spinal cord, brainstem, retina)
Amino acid derived NT’s
epinephrine, norepinephrine, dopamine, serotonin (5HT)
epinephrine
excitatory postsynaptic NT of sympathetic nervous system
norepinephrine
excitatory postsynaptic NT of sympathetic nervous system
dopamine
excitatory NT involved in reward motivated behavior
serotonin
inhibitory NT of the brain involved in mood, appetite, sleep, learning, increases contraction of GI tract in response to food intake
what neuropeptide can act as NTs
short chain amino acids, such as substance P, have diverse roles
gasotransmitter NT
nitric oxide
nitric oxide
NT causes smooth muscle relation, in blood vessels causes vasodilation leads to dec BP
true or false: nitric oxide is stored in vesicles
false - synthesized and released on demand
Acetylcholine
excitatory NT of neuromuscular junction in vertebrates; presynaptic NT of PNS and SNS; postsynaptic NT of PNS
glial cells
non-neuronal cells that nourish, support, protect the neurons by making sure the conditions are perfect for neuronal health
microglial cells
specialized macrophages which protect the CNS
macroglia
include astrocytes, Schwann cells, oligodendrocytes, satellite cells, ependymal cells
most abundant type of glial cell
astrocytes
function of astrocytes
- help provide blood supply to CNS neurons
- recycle neurotransmitters
- maintain proper ion levels
- help to form the blood-brain-barrier
blood-brain-barrier
selectively semipermeable membrane that covers the brain and regulates the passage of substances from the blood into the brain
satellite cells
similar function to astrocytes but function in the PNS - support ganglia
ependymal cells
create CSF for CNS
one oligodendrocyte can myelinate:
several neurons
one schwann cell can myelinate:
only a single neuron
during embryonic development, brain can be divided into _ areas:
3; forebrain, midbrain, hindbrain
forebrain develops into:
telencephalon and diencephalon
midbrain develops into:
mesencephalon
hindbrain develops into:
metencephalon, myelencephalon
telencephalon gives rise to:
cerebrum
diencephalon gives rise to:
thalamus, hypothalamus, pineal gland
mesencephalon gives rise to:
midbrain
metencephalon gives rise to:
pons, cerebellum
myelencephalon gives rise to:
medulla oblongata
frontal lobe function
- decision making, problem solving, judgement, planning for future, consequences of actions
- works with limbic system for memories and emotions
- attention/ concentration
temporal lobe function
speech/language, hearing
occipital lobe function
vision
parietal lobe function
spatial/visual perception, toucj/pain/temperature sensation and integration