Ch 42 Flashcards
nerve net
interconnected neurons with no central control organ (a few neurons that go talk to other neurons), found in invertebrates with radial nervous systems
radial symmetry (radial nervous system in invertebrates)
creatures with radial symmetry have nerve nets, they also have things that go out from all directions, these animals are often circular shaped, but not always, but no matter which direction you go, you get the same “piece of pie”, example: starfish, hydra, don’t have a brain or ganglia
bilateral symmetry (bilateral nervous system in invertebrates)
these animals can be split down the middle and have perfect symmetry on both sides, they have an increased number of nerve cells, a concentration of cells into a ganglia or brain, they have specialization of function into afferent, efferent, and CNS, they have more synapses, and they have cephalization, or a head
cerebral ganglia
serve as a primitive brain in some creatures with bilateral nervous systems
“ladder type” nervous system
when two solid, ventral, longitudinal nerve cords extend from the ganglia to the posterior end of the body, transverse nerves connect the two nerve cords and connect the brain with the eyespots, this arrangement is found in some bilateral nervous systems
What does the CNS consist of?
the brain and spinal cord
What does the PNS consist of?
sensory receptors and nerves
What are the two divisions of the PNS?
the somatic division and the autonomic division
What is the somatic division?
somatic responds to changes in the EXTERNAL environment, consists of receptors, afferent nerves, and efferent nerves
What is the autonomic division?
autonomic helps maintain homeostasis in the INTERNAL environment, consists of receptors, afferent nerves, efferent sympathetic nerves, and efferent parasympathetic nerves
What do the afferent (sensory) nerves of the somatic division do?
transmit information from receptors to the CNS, example: senses things on the skin
What do the efferent (motor) nerves of the somatic division do?
transmit information from the CNS to skeletal muscles, example: muscle information
What do the afferent (sensory) nerves of the autonomic division do?
transmit information from receptors in internal organs to CNS, example: stomach information
What do the efferent (motor) nerves of the autonomic division do?
transmit information from CNS to glands and involuntary muscle in organs, example: heart rate
What are the two types of nerves of the efferent nerves of the autonomic division?
sympathetic nerves and parasympathetic nerves
What do efferent sympathetic nerves do?
sympathetic nerves generally stimulate activity that results in mobilization of energy, example: speeds heartbeat, sympathetic helps the body respond to stressful situations
What do efferent parasympathetic nerves do?
action results in energy conservation or restoration, example: slows heartbeat but speeds digestion, parasympathetic helps body relax (parasympathetic paralyzes)
What does the vagus nerve do? What part of the PNS is it involved with?
slows heart, speeds digestion, autonomic efferent parasympathetic
What is the forebrain (in embryos) responsible for?
higher thought processes
What is the midbrain (in embryos) responsible for?
it’s the reflex center, responsible for blinking or flinching for example
What is the hindbrain (in embryos) responsible for?
it’s in charge of efferent, autonomic signals, example: blood pressure
What is dual innervation of the internal organs?
dual innervation: one organ can recieve impulses from both the sympathetic and parasympathetic motor neurons; one division increases the activity of an organ, one division decreases activity of an organ, the vagus nerve demonstrates dual innervation of the heart and stomach
What does the forebrain in embryos develop into in adults?
cerebrum, olfactory bulbs, thalamus, hypothalamus
cerebrum
largest, most prominent part of human brain; longitudinal fissure divides cerebrum into right and left hemispheres, each divided into lobes: frontal, parietal, temporal, and occipital lobes, it is the center of intellect, memory, consciousness, and language where higher thought processes occur, it also controls sensation and motor functions
olfactory bulbs
in charge of smelling things, found on bottom of brain
thalamus
connects forebrain to hindbrain, works as a relay switch, is an important relay center for sensory information, found in midbrain at the top of the brain stem, main sensory relay center for conducting information between spinal cord and cerebrum; neurons in thalamus sort and interpret all incoming sensory information (except olfaction) before relaying messages to appropriate neurons in cerebrum
hypothalamus
located just below the thalamus, the pituitary gland is connected to the hypothalamus by stalk of neural tissue; contains centers for control of body temperature, appetite, and fat metabolism; regulate pituitary gland; important in emotional and sexual responses, and in sleep-wake cycle, links the nervous to the endocrine system and regulates temperature, hunger, and thirst, “thermostat”
What do the midbrain and hindbrain in embryos become in adults?
the brainstem and cerebellum which encompasses the pons, medulla, and superior/inferior colliculi
What structures are included in the brain stem?
medulla, pons, and midbrain
medulla oblongata
continuous with spinal cord, primarily made up of nerves passing from spinal cord to rest of brain; contains vital centers (clusters of neuron cell bodies) that control heartbeat, respiration, and blood pressure, contains centers that control swallowing, coughing, and vomiting
What is the main association area in fish and amphibians?
the brainstem
superior and inferior colliculi
receive and integrate auditory and visual information before sending it on to the forebrain
What are the five functions of the cerebral cortex?
reasoning, motor, sensory, visual, and auditory
What is a sulcus?
a groove in the brain
What is a fissure?
a deep groove in the brain (deeper than sulcus)
What does the central sulcus separate?
frontal and parietal lobes
What is directly behind the central sulcus?
an area called the sensory area which is the 1st row of cells in parietal lobe
pons
forms bulge on anterior surface of brain stem; connects various parts of brain with one another; contains respiratory and sleep centers
midbrain (function, location)
just above the pons, it is a center for visual and auditory reflexes (ex. pupil reflex, blinking, adjusting ear to volume of sound)
cerebellum
second-largest division of brain, in charge of muscle coordination and refinement of movements, muscle tone, posture, equilibrium, helps plan and initiate voluntary activity, stores implicit memories
What is the name of the area of the cerebral cortex that is sensory?
humunculus
How is gray matter arranged?
into folds or convolutions
What do the sensory areas of the cerebrum do?
receive incoming information from eyes, ears, pressure and touch receptors, etc (recieve incoming sensory information)
What do the motor areas of the cerebrum do?
control movement of voluntary muscles
What do the association areas of the cerebrum do?
they are sites of intellect, memory, language, and emotion; they interpret incoming sensory information; they link the sensory and motor areas, learning, language, thought, judgment
What does the cerebrum consist of?
the lobes (frontal, parietal, temporal, occipital)
Where is the primary motor area located in the brain? The primary sensory area?
The motor area is right in front of the central sulcus, it is the last line of cells before the central sulcus, the sensory area is right behind the central sulcus, it is the first row of cells behind the central sulcus
Where is white matter found in the brain? What is its function?
it lies beneath the cerebral cortex, it consists of myelinated axons of neurons that connect various regions of the brain; axons are arranged into budles or tracts, it connects the following: 1) neurons within the same hemispheres, 2) right and left hemispheres, and 3) cerebrum with other parts of brain and spinal cord
corpus callosum
large band of white matter, connects right and left hemispheres
occipital lobes
contain the visual centers, stimulation of these areas, even by a blow on the head, causes the sensation of light, their removal causes blindness
temporal lobes
are the centers for hearing, stimulation by a blow causes a sensation of noise, removal of both auditory areas causes deafness, removal of one does not cause deafness in one ear, instead it produces a decrease in the auditory acuity of both ears
frontal lobes
have important motor and association areas
prefrontal cortex
is an association area in each frontal lobe that is crucial in evaluating information, making judgments and decisions, planning, and organizing responses
somatosensory area
in the anterior region of the parietal lobes, it recieves information regarding touch, pressur, heat, cold, and pain from sense organs in the skin, this region also recieves information regarding position of the body
reticular activating system (RAS) of the brainstem and thalamus
is a neural pathway within the brain stem and thalamus, the RAS receives messages from neurons in the spinal cord and from many other parts of the nervous system, and communicates with the cerebral cortex by complex neural circuts, when certain neurons of the RAS bombard the cerebral cortex with stimuli, an individual feels alert and can focus on specific thoughts, if the RAS is severely damaged the person may pass into a deep, permanent coma; (is the wakefulness/arousal system, the neurons filter the sensory input to it and the RAS selects which information is transmitted to the cerebrum)
Suprachiasmatic nucleus of the hypothalamus
is our body’s main biological clock, it receives information about light and dark and trasmits it to other nuclei that regulate sleep, found in the hypothalamus
hippocampus
categorizes information, consolidates memories, part of the limbic system
limbic system
is the “halo” or ring around the brain stem, it consists of a ring of forebrain structures that surround the brain stem and are interconnected by complex neural pathways. This system includes the amygdala, hippocampus, parts of the prefrontal cortex, the cingulate cortex, and areas in the thalamus, and hypothalamus, the limbic system is important in evaluating threat, in emotional expression, sexual behavior, motivation, and learning. (emotional aspects of behavior, motivation, sexual behavior, autonomic responses, biological rhythms)
amygdala
evaluates incoming information, signals danger, found in the limbic system
learning
acquiring information as a result of experience
memory
information is encoded, stored, and retrieved
implicit memory
unconscious memory for perceptual and motor skills (“procedural memory”, ex: remembering how to ride a bike), remembering how to do something, involves repeating the behavior until it becomes routine
explicit memory
factual memory of people, places, or objects, requires conscious recall of the information (hippocampus is critical in forming and retrieving these memories)
short-term memory
recalling information for a few minutes, information can be transferred into long-term memory, lasts for only a few seconds or a few minutes, can typically only hold 7 chunks of info at a time
What does plasticity mean?
changes
synaptic plasticity
the ability of the nervous system to modify synapses during learning and remembering, example: learning to walk, ride a bike–at first you were clumsy but your body adapted to help you after a lot of practice
long-term memory storage
in order for information to stay in the long-term memory, we must process it, the brain rehearses the material and encodes it, we recognize patterns and meaningfully associate the stimuli to past experience or knowledge, (gene activation, long-term functional changes at synapses)
Long-term potentiation (LTP)
increased sensitivity to an action potential by a post-synaptic neuron, potentiation means “to strengthen or make more potent”, this is the strengthening of synaptic connections by repeated electrical stimulation, information storage and forgetting depend on the strengthening and weakening of synaptic connections brought about by LTP and LTD
long-term depression (LTD)
long-lasting decrease in the strength of synaptic connections, after low-frequency stimulations of neurons there is a long-lasting decrease in the strength of the synaptic connections, information storage and forgetting depends on the strengthening and weakening of synaptic connections brought about by LTP and LTD
Layer of meninges on skull
outermost layer to innermost: dura mater, arachnoid mater, subarachnoid space, pia mater
Where does cerebrospinal fluid lie in regards to the meninges?
it lies between the arachnoid and pia mater in the subarachnoid space, the cerebrospinal fluid is secreted by the choroid plexuses that project from pia mater, it has nutrients from the blood, helps with the blood/brain barrier, is a shock absorber, and is found within ventricles and central canal of spinal cord
What is the choroid plexus?
groups of cells that produce fluid and proteins
What does the gray matter in the spinal cord contain?
cell bodies, dendrites, unmyelinated axons, association neurons, and glial cells
What does the central canal contain?
Cerebrospinal fluid
What does white matter contain within the spinal cord?
contains myelinated axons, tracts or pathways carry information up and down the spinal cord
Ascending tracts vs descending tracts
ascending tracts transmit information to the brain, descending tracts transmit information from the brain
What types of neurons does the dorsal horn contain? The ventral horn?
Dorsal=interneurons, ventral=motor neurons
How do drugs work/effect people? (simple explanation)
they alter mood by increasing or decreasing the amount of neurotransmitters within the brain
What three neurons are involved directly with reflex arcs?
sensory neurons, motor neurons, and interneurons
How does a withdrawal reflex work? (reflex arc)
1) a receptor senses pain, 2) a sensory neuron transmits the pain signal, 3) the signal reaches the interneuron and motor neuron, 4) the inter/motor neurons send the signal to the muscle to get away from whatever is causing pain, 5) muscle reacts
