unit 3 Flashcards
Ependymal cells
Neural support cells in the CNS. Neural cells that form a barrier between brain cells and the actual fluid cavities in the brain (ventricles) some secrete cerebrospinal fluid
Oligodendrocytes
Neural support cells in the CNS. They create the myelin sheaths. They can myelinate a few axions with its multiple arms.
Microglia (modified immune cells)
Neural support cells in the CNS. They are a so-so defense not great at defending brain from pathogens. They are good at being scavengers during brain development. they refine or prune the brain connections and refine circuitry.
Astrocytes
Neural support cells in the CNS. Physical cells that stand between blood supply and irreplaceable neurons (blood brain barrier). they synthesize substrates for ATP and pass substrates. Body guard and pass good stuff from the blood and prevent bad things from passing. they tend to the environment of the neuron.
Schwann cells (neurolemmocytes)
Neural support cells in the PNS. They create myelin sheaths for the PNS. one cell makes one myelin.
Satellite cells
Neural support cells in the PNS. Protect the neuron that are outside the CNS (outside the physical brain or spinal cord)
interneurons
Communicate within the CNS. They typically have lots of dendrites and look like coral.
Sensory neurons structure/look
They typically have a cell body in the middle with the axon and the dendrites coming out of the other two ends.
These cells are the functional unit of the nervous system
Neurons
These cells are the only part of the immune system that has access to the nervous system.
Microglia CNS
These cells form the myelin sheaths in the Peripheral nervous system
Schwann cells or neurolemmocytes. They are the 1:1 myelin creators in the PNS
These support cells provide neurons with essential bio-molecules for ATP production and form the blood- brain barrier.
Astrocytes of the CNS.
These cells line the walls of the fluid filled chambers of the brain (ventricles)
Ependymal cells of the CNS
These cells can myelinate more than one neuron.
The microglia of the CNS.
What mV do neurons typically rest at. What do they need to reach to generate an action potential?
They rest at -70mV and they need to reach -55mV or at least a +15 mV change.
What influxes at an excitatory synapse in the neuron
Na+ or Ca2+ influx. Creating a more + environment or depolarizing the cell.
What influxes in the inhibitory synapse?
Cl- influx, repolarizing the cell or creating a more - environment.
What is an EPSP
Excitatory post-synaptic potential. They increase the likelihood of an action potential. They depolarize the cell with an influx of Na+ or Ca+.
What is an IPSP
Inhibitory post-synaptic potential. The decrease the likelihood of an action potential. They repolarize or hyperpolarize the cell by Cl- influx or sometimes K+ efflux.
What are graded potentials?
Changes in the membrane potential in the dendrites and cell body upon binding a neurotransmitter. The more signal molecules that are received by either an excitatory or inhibitory synapse then dictates how strong the stimulus is. The faster/higher rate of signal molecules that are received the greater the change in a neuron’s membrane potential.
How the graded potentials happen in a little flow chart.
More signal molecules received –> more binding to receptors –> more channels open –> more ions move –> greater graded potential in target cell
What is the “trigger zone”
The area where the sum of the EPSPs and IPSPs is recognized and it is determined if there is enough voltage change to generate an action potential (at least +15mV). The trigger zone in a neuron is the Axon Hillock.
Sub/Supra graded potential
Sub means no action potential will be generated. Supra means it will.
What is integration (in terms of action potentials)
The sums of excitatory and inhibitory potentials. Integration is through spatial and temporal summation.
Spatial summation
When more than one neuron is stimulating the cell body at the same time. All over the Space of the neuron.
Temporal summation
Relates to the time the neurons are firing on the cell body. If they are close together they may add to create a larger depolarization. If they are farther apart they may act as individual waves.
What is propagation on the axon
the conduction of action potential on non-myelinated parts of the axon. This is slower movement.
What is Saltatory conduction on the axon
The conduction of action potential along the myelinated sheaths. Faster movement 100x faster than without the sheaths.
what happens when myelin is lost
the action potential cannot reach the next node of ranvier. The current is lost through the “empty” areas where the myelin once was. This happens in multiple sclerosis.
How does synaptic transmission occur
When the action potential reaches the axon terminal: Voltage gated Ca2+ channels are opened by the charge of the action potential. The influx of Ca2+ triggers the exocytosis of the neurocrine signal molecules into the synaptic cleft. Receptors on the post-synaptic cell (target cell) bind to the secreted molecule and trigger some form of response.
What happens on the post-synaptic cell?
The signal molecule will bind with a receptor and either open/close an ion channel or bind to a G-protein coupled receptor. They can create IPSP/EPSPs or trigger intracellular responses etc.
How does a signal stop in the synaptic cleft?
The signal molecule will either be: 1. re-uptake into the pre-synaptic cell or glial cells or 2. Diffused away from the cite or 3. broken down by an inactivation enzyme.
What are the seven types of neurocrines
Acetylcholine, Monoamines, amino acids, purines, gases, peptides, and lipids
What is Acetylcholine made up of
Acetyl CoA and choline. The enzyme acetyltransferase makes the molecule and the enzyme acetylcholinesterase breaks it down into acetate (waste) and choline (recycled into more Ach)
What are the cholinergic receptors (the receptors for acetylcholine)
Nicotinic receptors (Nm and Nn) and Muscarinic receptors (there are 5 of them)
What are the monoamine (catecholamines sub group) neurocrines (derived from one amino acid)
Epinephrine and norepinephrine,
also dopamine (do not need to know)
What are the other monoamines (not the catecholamines)
The indolamines: serotonin and melatonin.
Histamine
What are the adrenergic receptors (binding to catecholamines)
There are alpha 1 and 2, as well as beta 1,2,3
alpha 1,2 and beta 3 have affinity for norepinephrine
beta 2 has affinity for epinephrine
beta 1 has affinity equally for both.
What are the amino acid neurotransmitters and where are they located
Glutamine: (excitatory, CNS)
Aspartate: (excitatory, only brain)
Gamma-aminobutyric acid (GABA): (inhibitory, brain)
Glycine: (inhibitory spinal cord, sometimes excitatory)
What are the peptide neurocrines
Substance P and opioid peptides
- part of the pain perception and suppression in nerva system
What are the purine neurocrines
Adenosine, AMP, and ATP
- important in the sleep/wake cycles
What are the gas neurocrines
NO and CO
What are the lipid neurocrines
Cannabinoid (CB1 receptors) and THC
What are the branches of the autonomic nervous system (ANS)
Parasympathetic (rest and digest) and the sympathetic (fight or flight)
What is the ALASKA for the tonic organ systems
A: arterioles/veins
L: lymphoid tissue
A: adipose tissue
S: sweat glands
K: kidneys
A: adrenal medulla
What does the hypothalamus control as an integrating center
Temperature, Water balance, and hunger
What does the medulla oblongata control as an integrating center
The heart, respiration, vomiting, and swallowing
What does the Pons control as an integrating center
secondary respiratory control (modulation of ventilation rate, increases and decreases as needed)
Acetylcholine in skeletal muscles vs organs
Ach is always excitatory in skeletal muscles. But can be both in the organ systems.
What are varicosity
they are able to release neurotransmitters all over the surface of target cells. They kind of look like anal beads
Organs that are stimulated by the sympathetic branch. With norepinephrine or epinephrine/adrenergic receptors
Pupils dilate, salivary glands produce, heart rate and stroke increases, arterioles may dilate for more blood, bronchioles in lungs dilate, increased fat breakdown for more ATP production.
(all these systems are more essential in fight or flight)
Organs that are inhibited by the sympathetic branch. Produced by epinephrine and norepinephrine. Different receptors from the stimulating sympathetic
Digestion will decrease, pancreas will produce less enzymes and insulin, urine production will decrease
(all these systems are less essencial in fight or flight)
What organs does the parasympathetic branch inhibit
Slows heart rate, constricts pupils, constricts bronchioles,
What receptor does the parasympathetic branch use ACH on
It uses muscarinic receptors (M1-5) the odd numbers cause inhibition and the even cause excitation
What organs does the parasympathetic branch stimulate
increase in digestion, salivary glands produce watery secretions, insulin is released, urination is increased, erections
What receptor is ach binding to in the parasympathetic branch
Muscarinic receptors.
Cholinergic
acetylcholine often parasympathetic
Adrenergic
norepinephrine and epinephrine often sympathetic
What are the transverse tubules of the muscle cell
an extension of the sarcolemma where an action potential will travel down
What are the three autonomic pathways
Parasympathetic, sympathetic and adrenal sympathetic pathways
There is only one muscle pathway compared to the autonomic pathways
the somatic motor pathway
What is released from the somatic motor neuron
Always releases ach on nicotinic receptors which is always stimulating a contraction
what is the motor end plate
the region of the muscle that contains high concentrations of Ach receptors
the enzyme that metabolizes acetylcholine on the motor end plate
acetylcholinesterase
