lesson 4 and 5 Flashcards
neuronal junction
the site of transmission of electric nerve impulses between two nerve cells (neurons) or between a neuron and a gland or muscle cell (effector).
it is a specialized gap between neurons
SYNAPSE
anatomically demonstrated a narrow gap separating a neuron from another neuron
Ramon y Cajal
introduced the term SYNAPSE
Charles Scott Sherrington
-automatic muscular responses to stimuli.
-action that your body does in response to something — without you even having to think about .
Reflexes
- The circuit from sensory neuron to muscle response
- neurological and sensory mechanism that controls a reflex, an immediate response to a particular stimulus.
Reflex Arc
The simplest arrangement of a reflex arc consists of the___________; together, these units form a functional group.
receptor, an interneuron (or adjustor), and an effector
the speed of conduction through the reflex arc varied but was never more than about 15 meters per second (m/s). In contrast, previous research had measured action potential velocities along sensory or motor nerves at about 40 m/s.
Sherrington concluded that some process was
slowing conduction through the reflex, and he inferred that the delay must occur where one neuron communicates with another
Speed of a reflex and delayed transmission of a response
- is a phenomenon in which repeated stimuli within a brief time creates cumulative effect
- Temporal summation occurs when a series of subthreshold EPSPs in one excitatory fiber produce an AP in the postsynaptic cell
Temporal Summation (Summation over time)
- Synaptic inputs from separate locations combine their effects on a neuron.
- ________ is critical to brain functioning. Sensory input to the brain arrives at synapses that individually produce weak effects. However, each neuron receives many incoming axons, which are synchronized during sensory stimulation (Bruno & Sakmann, 2006). Spatial summation assures that a sensory stimulus will stimulate the cortical cells enough to activate them
Spatial Summation (Summation over space)
The bulk of the brain’s neurons are_________ — when they fire, they activate other neurons and propagate electrical signals throughout the brain. Inhibitory neurons do the opposite. The volley of chemical messages restrain, or inhibit, other neurons, making them less likely to fire messages of their own
excitatory
_____ also allows neurons to synchronize their firing, giving rise to rhythmic oscillations of activity, or brain waves.
Inhibition
In 1921, _____ devised a classical experiment, the outline of which came to him in several dreams. He awoke on the night of Easter Saturday in 1921 and wrote a few notes on a scrap of paper. To his horror, the next morning he could not decipher his own scrawl. He spent the rest of Easter Sunday in a desperate and unsuccessful attempt to reconstruct his dream. He was finally able to fall asleep that night, and he again dreamt of an epochal experiment. He again awoke from his dream, but this time he trusted his handwriting. He immediately repaired to his laboratory and conducted the experiment that had come to him in his dream, which he finished by the end of Easter Monday.
Otto Loewi
acids containing an amine group (NH2)
Amino acids
chains of amino acids
Neuropeptides
(a one-member “family”) a chemical similar to an amino acid, except that the NH2 group has been replaced by an N(CH3)3group
Acetylcholine
neurotransmitters containing one amine group (NH2), formed by a metabolic change in certain amino acids
monoamines
a category of chemicals including adenosine and several of its derivativesgases nitric oxide and possibly others
purines
—release of neurotransmitter in bursts from the presynaptic neuron into the synaptic cleft that separates this neuron from the postsynaptic neuron. An action potential often fails to release any transmitter, and even when it does, the amount varies
Exocytosis
, a neurotransmitter attaches to a receptor that opens the gates to allow a particular ion, such as sodium, to cross the membrane more readily.
ionotropic synapses
, a neurotransmitter activates a second messenger inside the postsynaptic cell, leading to slower but longer lasting changes. Neuropeptides diff use widely, affecting many neurons.
metabotropic synapses
After a neurotransmitter (other than a neuropeptide) has activated its receptor, many of the transmitter molecules reenter the presynaptic cell through transporter molecules in the membrane. This process, known as
reuptake
—receptors that detect the amount of transmitter released and inhibit further synthesis and release after it reaches a certain level. That is, they provide negative feedback (Kubista & Boehm, 2006).
autoreceptors
transmits signals between the brain and the rest of the body, including internal organs.
It is your body’s command center
The nervous system
2 main parts of the nervous system
central nervous system
peripheral nervous system
is made up of the brain and spinal cord.
The central nervous system
is made up of nerves that branch off from the spinal cord and extend to all parts of the body.
The peripheral nervous system
consists of peripheral nerve fibers that carry sensory information or sensations from peripheral organs to the CNS. The ____ also includes motor nerve fibers that exit the brain to carry commands for movement to the skeletal muscles.
The somatic nervous system (SNS)
controls the nerves of the body’s inner organs that cannot be controlled consciously. The ___ can be further subdivided into the sympathetic, parasympathetic, and enteric nervous systems. Some of the different activities controlled by the ___ include the heartbeat, digestion, subconscious breathing, blood pressure, and sexual arousal.
The autonomic nervous system (ANS)
Toward the back, away from the ventral
(stomach) side. The top of the brain is
considered dorsal because it has that
position in four-legged animals.
Dorsal
Toward the stomach, away from the
dorsal (back) side
Ventral
Toward the front end
Anterior
