Exam 2: Nervous Systems Flashcards
How do actional potentials differ from hormones?
Rapid and precise signaling
How do steroids differ from action potentials?
Slow, long-lasting, systemic signals
What is a ganglion?
A collection of neurons used for interpreting, receiving, and transmitting signals
How do neuron membranes relate to circuits?
Ions flows through a channel bringing charge and changing charge on either side of the membrane
What charge does the intracellular space near a neuron membrane exhibit during hyperpolarization?
Negative
What charge does the intracellular space near a neuron membrane exhibit at resting potential?
Negative
What charge does the intracellular space near a neuron membrane exhibit during depolarization?
Positive
What are action potentials?
voltage dependent signals created by change in membrane potential
What causes depolarization of neurons?
rapid opening of voltage gated Na+ channels releases Na+ in the cell
What causes repolarization of membranes
Na+ channels are closed and K+ channels out of the cell are opened
How does axon diameter affect the conduction velocity of axon potentials?
Conduction velocity increases with increase is axon diameter
What is patch claming?
laboratory manipulation individual membrane channels in neurons to study membrane potential and electric capabilities
How does temperature affect generation of action potentials?
Generation and transmission occurs faster because voltage-gated ion channel kinetics are faster at higher temperatures
How do myelin sheath speed up action potentials?
The action potential jumps between the nodes of Ranvier
Do endotherms have larger or smaller diameter axons? Why?
Smaller because their higher body temps allow them to still conduct signals quickly
What is the first step in transmitting neurotransmitters across a synapse?
Action potential opens voltages gated Ca2+ channels
What occurs after an action potential open voltage gated Ca2+ channels in a presynaptic neuron?
Vesicle containing neurotransmitters mobilize and adhere to the presynaptic membrane
How do postsynaptic neurons receive neurotransmitters?
neurotransmitters bind to the postsynaptic receptor and triggers opening of ion channels
What are the three kinds of neurotransmitters?
Cholinergic compounds (acetylcholine)
Biogenic Amine compounds (Norepinephrine, dopamine, serotonin, GABA)
Amino Acids (glutamate)
What do ionotropic neurotransmitters do?
Induce a conformational change in postsynaptic receptor that opens ion channel
What do metabotropic neurotransmitters do?
Bind to the postsynaptic receptor and trigger release of a G-coupled protein, which causes ion channels to open
What is an excitatory post synaptic potential?
When a neurotransmitter triggers depolarization of the membrane
What is an inhibitory post synaptic potential?
when a neurotransmitter triggers polarization of the membrane
Why is it important that neurons create both inhibitory and excitatory post synaptic potentials?
Because which neurotransmitters are expresses influences likelihood of action potential being generated
What is synaptic depression?
A gradual decrease in amplitude of post synaptic potentials
What is synaptic facilitation?
Repeated stimulation by presynaptic neuron increases amplitude of postsynaptic potentials
What is the benefit of synaptic facilitation and depression?
They increase or decrease signal intensities based on need
What is the central nervous system (CNS)?
Contains the majority of neurons and is where information processing occurs
What is the peripheral nervous system (PNS)?
Neurons that receive stimuli and bring them to the CNS, and carry information away from the CNS
What is a reflex?
Reception of signal by afferent neuron -> interpretation by CNS interneurons -> PNS motor neurons receive signal from CNS
What is centralization of the nervous system described as?
Localization of integrating neurons in a central area
What is a benefit of centralization?
It is easy to receive messages and distinguish them from one another
What is cephalization of the nervous system?
Integration neurons and structures are concentrated at one end of the body
How is the CNS of insects unique from other animals?
It is located ventral
Describe an arthropod’s CNS
Ganglia extend in a line from the brain and down the abdomen
Describe a vertebrate’s CNS
Segmented nerves run down from the brain and along the spinal cord
What are the five principles of organization in vertebrate brains?
- Brain function is modular - Parts in the brain can change function over a person’s lifetime and areas rely on each other for function
- Brains have integrated maps - Specific areas in the brain can be identified for specific functions
- Size matters - larger brains are more advanced
- Brain evolution relates to expansion of the forebrain
- Neural circuits are plastic
Why does a larger brain mean it is more advanced?
Larger brains have more neurons and can send and receive signals faster
Why is expansion of the forebrain associated with brain evolution?
The forebrain relates to personality and late gratification
Why are neural circuits plastic?
Signal strengths can be manipulated, and synapses can be generated to form new pathways
What are the two divisions of the peripheral nervous system?
The somatic division and the autonomic division
What is the purpose of the somatic nervous system?
To integrate external stimuli and control voluntary movement of skeletal muscle
What is the purpose of the autonomic nervous system?
To integrate internal stimuli and control a wide variety of tissues
What are three major tissues the autonomic nervous system controls?
Smooth muscle, cardiac muscle, and glands
How many motors neurons are used to connect the CNS to skeletal muscle?
One
In the autonomic nervous system, what connects the CNS to target tissues?
a preganglionic neuron, a ganglion, and then a post ganglionic neuron
What are the three divisions of the autonomic nervous system?
Sympathetic, parasympathetic, and enteric
What is the purpose of smooth muscle?
to regulate internal functions
Why is it beneficial for the autonomic nervous system to have multiple neural connections when sending signals?
Allows one signal to trigger many responses
What neurotransmitters are used in the sympathetic nervous system?
Cholinergic and adrenergic
How do the preganglionic and postganglionic neurons compare in the sympathetic nervous system?
Preganglionic neurons are short and postganglionic neurons are long
What neurotransmitters are used in the parasympathetic nervous system?
Cholinergic transmitters?
How do the preganglionic and postganglionic neurons compare in the parasympathetic nervous system?
Preganglionic neurons are long and post ganglionic neurons are short
What kind of neurotransmitters does the enteric nervous system use?
All different kinds
What does the enteric nervous system control?
Gut signaling
What is the vagus nerve?
The longest nerve in the body that conducts 90% of enteric signals
What nervous system sends the strongest signals the CNS?
Enteric
What do four things do biological clocks control?
Temperature, sleep cycle, urine volume, Na+/Ca2+ excretion
What are biological clocks mostly determined by?
Light availability
What is a free running rhythm?
When a natural circadian rhythm occurs in the absence of cues
What do clock genes do? How do they work?
Negative feedback loop where BMAL1 and CLOCK trigger PER expression which is inhibitory to BMAL
How do clock gene pathways regulate circadian rhythms?
Regulate secretion of sleep hormones like melatonin
