Physiology Chapter 4: Principles of Neural and Hormonal Communication BIOL 2305-017 (23314)
Terms in this set (95)
Use neurons and neurotransmitters to control the body's muscular and glandular activities. Also controls body's higher functions.
Uses chemical messengers to produce slow but long-lasting results.
These tissues, when stimulated, produce electrical signals.
A change in potential that goes away from 0 mV.
A change in potential that goes toward 0 mV.
The membrane goes back to its resting potential after being depolarized.
An increase in negative potential that goes past resting membrane potential. More charges are separated than at resting potential.
These channels are open all the time and allow unregulated passage of the specific molecules.
Can be open and closed. Thus, their molecules can be let in some times but not others. Changes in shape of protein receptors depends on status. 4 types: (1) Voltage-gated channels, (2) chemically gated channels, (3) mechanically gated channels, and (4) thermally gated channels.
Open and close in response to changes in membrane potential.
Chemically gated channels
Open and close in response to the binding of a specific chemical messenger with a membrane receptor in close association with the channel.
Mechanically gated channels
Open and close in response to mechanical deformation.
Thermally gated channels
Open and close in response to local changes in temperature.
Local changes in membrane potential that occur in varying grades or degrees of magnitude or strength.
Any flow of electrical charges.
The hindrance of the movement of electrical charge.
Brief, rapid, large (100 mV) changes in membrane potential during which potential switches. Outside becomes more positive than the inside. Nondecremental.
At this level (typically -50 to -55 mV) explosive depolarization takes place, resulting in a temporary membrane potential of 30 mV.
After the membrane potential reaches 30 mV, it often depolarizes too much. Basically the membrane potential overshoots the resting membrane potential of -70 mV.
The portion of the action potential that goes positive 90-30 mV).
Action potentials are referred to as this because of their appearance of graphs.
Neurons do this when they are triggered to undergo an action potential.
A single nerve cell that consists of 3 parts, the dendrites, cell body, and axon.
These extend from the cell body receive signals from other neurons and have protein receptors for neurotransmitters.
Houses the neuron's nucleus and organelles.
"Nerve Fiber" A single, tubular, elongated extension that sends signals away from the cell body and toward other cells.
Side branches of the axon.
The axon and the part of the cell body from which the axon leaves.
Located at the end of the axon. Release chemical messengers that influence other cells.
The spread of the action potential down every patch of the membrane of the neuron's axon.
A period of time when part of the neuron cannot be activated. Has two parts, absolute refractory period and relative refractory period.
Absolute Refractory Period
The time period when a patch of membrane is totally unresponsive to stimulation. Voltage-gated Na channels cannot be reopened until resting potential is restored. Only one activation potential can occur at a time.
Relative Refractory Period
Occurs after the absolute refractory period. Allows another action potential to occur if there is a significantly stronger triggering event than necessary.
In order for an action potential to take place, the membrane potential must be depolarized to the threshold potential. Otherwise, no action potential will take place.
These neuron fibers are covered with myelin at regular intervals.
Composed primarily of lipids. Consists of myelin-producing cells, oligodendrocytes in the CNS and Schwann cells in the PNS.
Produce myelin in the CNS.
Produce myelin in the PNS.
Nodes of Ranvier
These are intervals in the neuron that are not covered in myelin.
Local current "jumps" over each segment of myelin. When one node of Ranvier is depolarized, the next node's Na channels are opening as well. Good example of positive feedback system.
When nerve fiber is damaged, the Schwann cell phagocytize the debris, form a tunnel to guide the tunnel, and secretes a chemical for the fiber to follow.
When a nerve supplies a structure.
The junction between two neurons.
The axon terminal ends the signal toward the synapse.
The slight swelling toward the end of the neuron. Contains the synaptic vesicles.
Contain the neurotransmitters.
Chemical transmitters which bind to protein receptors on the postsynaptic neurons. Activated by action potentials
Receive the neurotransmitters and send action potentials away from the synapse.
The actual space between two neurons.
The part of the postsynaptic membrane directly underlying the synaptic knob.
A synapse that results in a neuron brought closer to action potential.
A synapse that results in a neuron brought farther from an action potential.
Excitatory postsynaptic potential (EPSP)
A postsynaptic potential change that occurs at an excitatory synapse.
Conversion of an electrical signal from the presynaptic neuron to the postsynaptic neuron by chemial means results in this.
Inhibitory postynaptic potential (IPSP)
A postsynaptic potential change that occurs at an inhibitory synapse.
Grand Postsynaptic Potential (GPSP)
The total potential in the postsynpatic neuron.
A successive firing of individual action potentials.
A simultaneous or near simultaneous firing of action potentials.
Small, rapid-acting molecules that trigger the opening of specific ion channels to bring about a change in potential in the postsynaptic neuron.
Larger molecules that are made up of anywhere from 2 to approximately 40 amino acids.
Neuropeptides are stored in these.
Chemical messengers that do not bring about EPSPs or IPSPs. Rather, they bring about long-term changes that depress or enhance the action of the synapse.
If a neuron releases less neurotransmitters due to another neuron, this has taken place.
If a neuron releases more neurotransmitters due to another neuron, this has taken place.
When a neuron has many other neurons synapsing onto it. Increases sensitivity in pathway but decreases precision.
When a single neuron branches out and affects many other neurons. Spreads out signal and amplifies it.
Extracellular chemical messengers
The most common way that cells communicate. 4 types: (1) Paracrines, (2) neurotransmitters, (3) hormones, and (4) neurohormones.
The cell that a messengers goes after.
Local chemical messengers that affect only the neighboring cells that are immediately adjacent.
Long-range chemical messengers that are secreted into the bloodstream by endocrine glands. Typically have long-lasting, far-reaching effects.
Hormones that are released into the bloodstream by neurosecretory neurons.
The process by which incoming signals are conveyed to the target cell's interior for execution.
The extracellular messenger that binds to its receptor and brings about inward change.
This is stimulated by the binding of a first messenger to a receptive site. This then activates a particular intracelluar protein that carries out the necessary response.
These synapses use rapid responses.
These synapses use second messengers and are slower but produce longer lasting results.
The study of homeostatic chemical adjustments and other activities accomplished by hormones.
Highly water-soluble and have low solubility.
High lipid solubility and poorly water soluble.
Large precursor proteins that are synthesized by ribosomes on the rough endoplasmic reticulum. Then go to the Golgi complex.
Cyclic Adenosine Monophosphate (Cyclic AMP or CAMP)
One of the major second messengers that hydrophilic hormones use.
Located on the cytoplasmic side of the plasma membrane. Activated by the binding of an extracellular membrane to a membrane receptor. Converts ATP to AMP.
Releases alpha, beta, and gamma subunits. The alpha subunit activates adenylyl cyclase.
Protein kinase A
CAMP activates this. This enzyme phosphorylates a particular protein, which then changes shape and performs the required task.
This enzyme is a protein effector that is bound to the inner side of the membrane. Breaks down phosphatidylinositol biphosphate.
Phosphatidylinositol biphosphate (PIP2)
A component of the tails of the phospholipid of the tails of the phospholipid molecules within the membrane itself.
One of the broken-down products of phosphatidylinositol biphosphate.
Inositol triphosphate (IP3)
One of the broken-down products of phosphatidylinositol biphosphate. Responsible for mobilizing intracellular calcium stores to increase cytosolic calcium.
An intracellular calcium-binding protein. Induces a change in shape for a particular protein.
Cyclic Guanosine Monophosphate (Cyclic GMP)
Serves as a second messenger in a system analogous.
This effect amplifies the signal.
Hormone response element (HRE)
A special attachment site where a hormone binds with DNA.
Quickly transmits signals throughout the body via electrical impulses.
Secretes hormones into the blood for long-distance travel.
The study of the relationship between the nervous and endocrine systems.