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
Toward the rear end
Posterior
Above another part
Superior
Below another part
Inferior
Toward the side, away from the midline
Lateral
Toward the midline, away from the side
Medial
Located close (approximate) to the point
of origin or attachment
Proximal
Located more distant from the point of
origin or attachment
Distal
On the same side of the body (e.g, two
parts on the left or two on the right)
Ipsilateral
On the opposite side of the body (one
on the left and one on the right)
Contralateral
A plane that shows brain structures as
seen from the front (or frontal plane)
Coronal plane
A plane that shows brain structures as
seen from the side
Sagittal plane
A plane that shows brain structures as
seen from above (or transverse plane)
Horizontal plane
________________ consists of neurons that receive information from and send commands to the heart, intestines, and other organs.
The autonomic nervous system
2 parts of the autonomic nervous system
the sympathetic and parasympathetic nervous system
It prepares the organs for vigorous activity, consists of chains of ganglia just to the left and right of the spinal cord’s central regions (the thoracic and lumbar areas).
These ganglia are connected by axons to the spinal cord. Sympathetic axons prepare the organs for “fight or flight”—increasing breathing and heart rate and decreasing digestive activity
The Sympathetic
It facilitates vegetative, nonemergency responses. The term para means “beside” or “related to,” and parasympathetic activities are related to, and generally the opposite of, sympathetic activities.
For example, the sympathetic nervous system increases heart rate, but the parasympathetic nervous system decreases it.The parasympathetic nervous system increases digestive activity, whereas the sympathetic nervous system decreases it.
Although the sympathetic and parasympathetic systems act in opposition, both are constantly active to varying degrees, and many stimuli arouse parts of both systems
The Parasympathetic/craniosacral system
_______, the posterior part of the brain, consists of the medulla, the pons, and the cerebellum. Th e medulla and pons, the midbrain, and certain central structures of the forebrain constitute the brainstem
The hindbrain
cranial nerves
I. Olfactory
II. Optic
II. Oculomotor
IV. Trochlear
V. Trigeminal
VI. Abducens
VIl. Facial
VIll. Statoacoustic
IX. Glossopharynge
X. Vagus
XI. Accessory
XII. Hypoglossal
I. Olfactory
Smell
II. Optic
Vision
III. Oculomotor
Control of eye movements; pupil constriction
IV. Trochlear
Control of eye movements
V. Trigeminal
Skin sensations from most of the face; control of jaw muscles for chewing and swallowing
VI. Abducens
Control of eye movements
VIl. Facial
Taste from the anterior two thirds of the tongue; control of facial expressions, crying, salivation, and dilation of the head’s blood vessels
VIll. Statoacoustic
Hearing; equilibrium
IX. Glossopharynge
Taste and other sensations from throat and posterior third of the tongue; control of swallowing, salivation, throat movements during speech
X. Vagus
Sensations from neck and thorax; control of throat, esophagus, and larynx; parasympathetic nerves to stomach, intestines, and other organs
XI. Accessory
Control of neck and shoulder movements
XII. Hypoglossal
Control of muscles of the tongue
_________ is in the middle of the brain
The topmost part of the brainstem, the connection central between the brain and the spinal cord.
There are three main parts of the midbrain - the colliculi, thetegmentum, and tectum
The midbrain
_________ is the most anterior and most prominent part of the mammalian brain. It consists of two cerebral hemispheres (left and right hemispheres)
Each hemisphere is organized to receive sensory information, mostly from the contralateral (opposite) side of the body, and to control muscles, mostly on the contralateral side, by way of axons to the spinal cord and the cranial nerve nuclei
The forebrain
________ of the brain are a communicating network of cavities filled with cerebrospinal fluid (CSF) and located within the brain parenchyma.
The ventricles
___________ cushions the brain against mechanical shock when the head moves. It also provides buoyancy. Just as a person weighs less in water than on land, cerebrospinal fluid helps support the weight of the brain. It also provides a reservoir of hormones and nutrition for the brain and spinal cord.
Cerebrospinal fluid
The ___________ (from a Latin word meaning “seahorse,” a shape suggested by the _________) is a large structure between the thalamus and the cerebral cortex. The gist of that discussion is that the ___________ is critical for storing certain kinds of memories. People with hippocampal damage have trouble storing new memories, but they do not lose the memories they had before the damage occurred
hippocampus
Several structures lie on the ventral surface of the forebrain, including the nucleus basalis, which receives input from the hypothalamus and basal ganglia and sends axons that release acetylcholine to widespread areas in the cerebral cortex The nucleus basalis is a key part of the brain’s system fors. Patients with Parkinson’s disease and Alzheimer’s disease have impairments of attention and intellect because of inactivity or deterioration of their nucleus basalis.
Basal Ganglia
__________is an endocrine (hormone-producing) gland attached to the base of the hypothalamus by a stalk that contains neurons, blood vessels, and connective tissue
In response to messages from the hypothalamus, the pituitary synthesizes and releases hormones into the bloodstream, which carries them to other organs.
pituitary gland
a structure deep in your brain, acts as your body’s smart control coordinating center. Its main function is to keep your body in a stable state called homeostasis. It does its job by directly influencing your autonomic nervous system or by managing hormones.
hypothalamus
It is a pair of structures (left and right) in the center of the forebrain.
The term is derived from a Greek word meaning “anteroom,” “inner chamber,” or “bridal bed.”
Most sensory information goes first to the thalamus, which processes it and sends output to the cerebral cortex. An exception to this rule is olfactory information, which progresses from the olfactory receptors to the olfactory bulbs and then directly to the cerebral cortex
Thalamus
– outer portion of the forebrain
Cerebral Cortex
- intermediate level of the midbrain; covers several other midbrain structures, although it is covered by the tectum; nuclei for the third and fourth cranial nerves, parts of the reticular formation, and extensions of the pathways between the forebrain and the spinal cord or hindbrain.
Tegmentum
– the roof of the midbrain
Tectum
The _________is a large hindbrain structure with many deep folds. It has long been known for its contributions to the control of movement, and many older textbooks describe the cerebellum as important for “balance and coordination.”
cerebellum
- the swellings on each side of the tectum; both are important for sensory processing
Superior and inferior colliculus
colliculus for hearing
the inferior colliculus
colliculus that is mainly for vision
superior colliculus
lies anterior and ventral to the medulla; like
the medulla, it contains nuclei for several cranial nerves. Theterm pons is Latin for “bridge”; the name reflects the fact that many axons in the pons cross from one side of the brain to the other. Th is is in fact the location where axons from each half of the brain cross to the opposite side of the spinal cord so that the left hemisphere controls the muscles of the right side
of the body and the right hemisphere controls the left side.
pons
