Midterm 2: Chapter 5/6/7 Flashcards
Stretch sense activated channels (2)
The anatomy+what happens
- The base of each hair is wrapped in a dendrite of a touch neuron. When you bend a hair or otherwise mechanically displace it, the encircling dendrite is stretched
- The displacement opens stretch activated channels in the dendrite’s membrane. When open, these channels allow an influx of sodium ions sufficient to depolarize the dendrite to threshold. At threshold, the voltage-activated sodium and potassium channels initiate a nerve impulse that conveys touch information to your brain.
end plate
The axon terminal contacts a specialized area of the muscle membrane called an end plate, where the axon terminal releases the chemical transmitter acetylcholine
Explain to me muscle contraction
When a motor neuron’s axon collaterals contact a muscle fiber end plate, acetylcholine attaches to receptor sites on the end plate’s transmitter-activated channels, opening them. These large membrane channels allownsimultaneous influx of Na and efflux of K. Acetylcholine does not enter the muscle but rather attaches to
transmitter-activated channels on the end plate to depolarize the muscle to the threshold for its action potential.
myasthenia gravis
the thymus, an immune system gland that normally produces antibodies that bind to foreign material like viruses, makes antibodies that bind to the acetylcholine receptors on muscles, causing weakness and fatigue
Sensory stimuli activate channels on neurons to initiate a nerve impulse, and the nerve impulse eventually ——-
activates channels on
motor neurons to produce muscle contractions.
adrenaline/epiniephrine (2)
Produced where+ what it did
- produced by the adrenal glands located atop the kidneys
- speed up heart rate
In mammals, the chemical that accelerates heart rate is
norepinephrine
Acetacholine (3)
What it does+ what is it made from?
- inhibits heart rate
- activates skeletal muscle
- Made from acetate (found in acidic foods) and choline (found in fats)
neurotransmitters
Chemical messengers released by a neuron onto a target to cause an excitatory or inhibitory effect
the real difference between neurotransmitters and hormones is
the distances they travel
Excitatory neurotransmitter ex+ what happens (2)
- glutamate, acetacholine
- Nat+ channel causes depolarization
inhibitory neurotransmitter+what happens (2)
- GABA, Glycine
- related to Cl- channel or efflux of K+
Structure/sequence of the synapse
axon->dendrite->soma-> axon->dendrite etc
the upper part of the synapse is
the axon terminal, or end foot
the lower part of the synpase is
the receiving dendrite
synaptic vesicles
- Contain neurotransmitter molecules
Storage granules
stores synpatic vesicles
synaptic cleft (2)
What must neurotransmitter do?
- The small gap that seperate the terminal and the dendrite
- neurotransmitter chemicals must bridge this gap to carry a message from one neuron to the next
The surrounding astrocyte contributes to chemical neurotransmission in several ways (3)
- supplying the building blocks for neurotransmitter synthesis
- by confining the movement of neurotransmitters to the synapse
- by mopping up excess neurotransmitter molecules
tripartite synapse
functional integration and physical proximity of the presynaptic membrane, postsynaptic membrane, and their intimate association with surrounding astrocytes
presynaptic membrane
- axon terminal: Neurotrasmitter is stored in synaptic vesicles, contain mitochondria
Neurotransmitter is released…
on the presynpatic membrane side of the synpase
microtubules
transport structure that carriers substances to the axon terminal
Postsynpatic membrane
- the dendritic spine: contain receptors
Gap junction
Fused prejunction and postjunction cell membrane in which connected ion channels form a pore that allows ions to pass directly from one neuron to the next. Constitute a regulated gate between cells because they can
either be open or closed. Allow no such plasticity and are built for speed
and efficient communication
Gap junction elimnates
delay in synpatic cleft
4 steps of neurotransmission
- neurotransmitter synthesized and stored in the axon terminal
- Transported to the presynpatic membrane and released in respinse to an action potential
- Able to activate the receptors on the target cell membrane located on the postsynpatic membrane
- Inactivated or will contine to indefinetly
First way in how neurotransmitters are made
synthesized in the axon terminal from building blocks that are often derived from food
Transporters
are protein molecules that move building blocks across cell membranes (to make transmitters), and they are responsible for packaging some
neurotransmitter classes into vesicles.
Mitochondria in the axon
terminal
provide the energy needed both to synthesize precursor chemicals into the transmitter and to power transporters.
Tryptophan
Precursor for seretonin (found in most protein based foods)
Second way of how neurotransmitters are made
- Synthesized in the cell body acording to DNA instructions and transported on microtubules to axon terminal
The three places neurotransmitters are stored:
- Stored in granules
- Attached to microfilaments
- Attached to the presynpatic membrane