Chapter 40: Nervous System Flashcards
Big structural differences between nervous systems of invertebrates verses vertebrates?
invertebrates contain fewer neurons arranged in less complex networks
What is feedforward excitation?
excitement on a chain of neurons in one direction, transmitting information forward from sense organs through the brain
What is feedback excitation?
excitatory neurons communicate with neurons at earlier steps in neural pathways—-positive feedback
What is feedback inhibition?
Excitatory neurons activate neurons that inhibit the excitatory neurons, preventing neural circuits from becoming too active—negative feedback
How do PET scans work?
tracks brains usage of glucose and uses radioactivity
How do fMRIs work?
shows changes conformational of O2 binding to hemoglobin in the blood, uses large magnets, no radioactivity
What type of neural systems do Cnidarians and echinoderms have?
nerve nets – loose meshes of neurons organized within their radial symmetry, give sense of orientation, easy to replace
Their neurons lack clearly differentiated dendrites and axons
no brain, but nerve cells may be more concentrated in some regions
immobile organisms
What type of neural systems do echinoderms (ex. sea stars) have?
some nerves – bundles of axons enclosed in connective tissue and following the same pathway
nerve ring: center point
If the radial nerve serving an arm is cut, the arm can still move, but not in coordination with the other arms
—allows for fragmentations, mobility
uses chemical synapses—slow responses
What is Cephalization?
the formation of a distinct head region containing a control center (ganglia or brain) and major sensory structures – is a key evolutionary development
speeds up response time
What are nerve cords?
extend from the central ganglia to the rest of the body – connected to smaller nerves
What type of neural systems do flatworms have?
small brain (consisting of a pair of ganglia at the anterior end) is connected by 2 or more longitudinal nerve cords to nerve nets in the rest of the body
has CNS, PNS, eyespots
What type of neural systems do arthropods have?
insects have a head region that contains a brain (consisting of dorsal and ventral pairs of ganglia) and major sensory structures, usually eyes and antennae
In arthropods with fused body segments, as in the thorax of insects, ganglia are fused into larger masses forming secondary control centers
multi-lobed brain, cord runs in duality
ex) grasshopper
What type of neural systems do mollusks have?
(e.g., clams, snails, octopuses) also have neurons clustered into paired ganglia and connected by major nerves
What type of neural systems do octopuses have?
The octopus has a complex, lobed brain with clearly defined sensory and motor regions
nerve ring design similar to star fish which was found to be able to do computations independently of the brain
What does the CNS consist of?
brain and spinal cord
What does the PNS consist of?
consists of all the nerves and ganglia that connect the brain and spinal cord to the rest of the body
What is the structure of nerve cords in vertebrate?
hollow and fluid-filled
Where are ganglia greatly reduced in vertebrates?
gut, contains extensive interneurons networks instead
How does the neural tube develop into the human brain?
the anterior end develops into the brain, and the rest develops into the spinal cord
The cavity of the neural tube becomes the fluid-filled ventricles of the brain and the central canal through the spinal cord
Formation of neural tube?
neural plate in between ectoderm
neural plate expands, curls up, folds in on itself to form tube
How does the anterior neural tube develop?
develops into the hindbrain, midbrain, and forebrain
What is the development of the hindbrain?
gives rise to the cerebellum and medulla oblongata
What does the cerebellum do?
integrates sensory signals from eyes, ears, and muscle with motor signals from the telencephalon and pons
What is the pons?
major traffic center for information passing between the cerebellum and the higher integrating centers of the adult telencephalon
What does the medulla oblongata do?
controls vital involuntary tasks such as respiration and blood circulation
What is the development of the midbrain? role?
adult midbrain = brain stem
role–centers for coordinating reflex responses (involuntary reactions) to visual and auditory input and relays signals to the telencephalon
What is the structure of the brain stem?
pons and medulla and midbrain
What is the development of the forebrain? role?
develops into the cerebrum (telencephalon) = largest part of brain
role—Controls higher functions such as thought, memory, language, and emotions, and voluntary movements
Where are the hypothalamus and thalamus located?
forebrain
Role of thalamus?
receives sensory input and relays it to the regions of the cerebral cortex
Role of hypothalamus?
primary center for homeostatic control over the internal environment
How many spinal nerves are in the human body?
31 pairs
How many cranial nerves are in the human body?
12 pairs
What are the two divisions of the PNS?
autonomic and somatic
What does the somatic nervous system control?
body movements that are primarily conscious and voluntary – it also controls reflexes and shivering, and maintains posture and balance
What are motor neurons?
carry efferent signals from the CNS to the skeletal muscle
Dendrites and cell bodies of motor neurons are located in the spinal cord (CNS)
voluntary
What do the somatic portions of the cranial and spinal nerves consist of?
axons
What does the autonomic nervous system control?
controls involuntary processes of digestion, sweat glands, and circulation, many functions of reproductive and excretory systems, and contraction of smooth muscles in all parts of the body
What does the sympathetic nervous system control?
increases heart rate and blood pressure, and prepares the body for emergency responses
pupils dilate, salivary glands inhibit secretion, increases HR, dilates bronchioles, inhibits stomach activity, increase glucose release, inhibits digestion, inhibits bladder muscles and sexual arousal
What does the parasympathetic nervous system control?
digestion, rests body after stress
What is the goal of meditation?
turn` of sympathetic nervous system
What is the role of the CNA in the negative feedback pathway?
integration
What is the distribution of grey and white matter in the brain?
white matter centrally located with axon tails arriving with information
grey matter on the outer part of the brain which takes in the information
What is the distribution of grey and white matter in the spinal cord?
grey matter centrally located with axon tails arriving with information—can break though white matter
white matter on the outer part which sends out the information
What does the ventricles in the brain contain?
cerebrospinal fluid
What is the structure and function of the meninges?
surround and protect brain and spinal cord
3 layers: inner most —> outmost (PAD)
Pia matter, arachnoid, dura matter
What is the function of the cerebrospinal fluid?
circulates through the ventricles of the brain, through the central canal of the spinal cord, and between two of the meninges
cushions the brain and spinal cord, nourishes the CNS, and protects it from toxic substances
What is the blood-brain barrier?
Epithelial cells of capillary walls in the brain are sealed together by tight junctions
protects the brain and spinal cord from viruses, bacteria, and toxic substances protects the brain and spinal cord from viruses, bacteria, and toxic substances
prevents blood from entering CSF
What diffuses across the epithelial cell membranes by diffusion?
Oxygen, CO2, alcohol, and anesthetics
What is moved across the epithelial cell membranes by transport proteins?
ketones and glucose
Can neurotransmitters cross the blood-brain barrier?
yes
Why does Benadryl make you drowsy?
b/c it can cross the blood-brain barrier
Where do Pairs of spinal nerves connect with the spinal cord?
at spaces between the vertebrae
Role and function of spinal cord?
The spinal cord carries impulses between the brain and PNS, and contains interneuron circuits that control motor reflexes
What are reflexes?
programmed movements that take place without conscious effort
Where are spinal reflexes located at?
grey matter
What is the patellar tendon reflex?
knee-jerk response, n which a tap to the tendon just below the knee cap causes the leg to kick; this is a classical example of the stretch reflex
How many pairs of cranial nerves originate from the brain stem?
all but 2
What is the role of the grey matter centers in the brain stem?
control heart and respiration rates, blood pressure, constriction and dilation of blood vessels, coughing, and reflex activities of the digestive system (e.g., vomiting) without control by the cerebrum
What is the reticular formation? location?
complex network of interconnected neurons that integrates the information and sends signals to other parts of the CNS
runs from the spinal cord, through the brain stem, to the thalamus
What is the ascending reticular formation?
(reticular activating system) conveys stimulatory signals via the thalamus that activate the cerebral cortex – responsible for the sleep-wake cycle and various levels of alertness and consciousness
What is the descending reticular formation?
conveys information from the hypothalamus to interneurons in the spinal cord that control skeletal muscle contraction – controlling muscle movement and posture
Where does the cerebellum receive sensory input from?
what does it do with this info?
role in feedback system?
muscles and joints, from balance receptors in the inner ear, and from receptors of touch, vision, and hearing
compares them with signals from the cerebrum that control voluntary body movements
integrator
what is the cerebral cortex and composition?
thin outer shell of gray matter (cerebral cortex) covering a thick core of white matter
What is the largest part of the brain in humans?
cerebrum
What is the basal nuclei?
consisting of several regions of gray matter, are located deep within the white matter
are gray- matter centers that surround the thalamus on both sides of the brain
moderate voluntary movements directed by motor centers in the cerebrum
computational centers
What are sulcus?
crevisies
What are gyrus?
outward folding
What are grey matter centers?
route information to and from the cerebral cortex, and between the forebrain, brain stem, and cerebellum
What does the thalamus do?
receives sensory information and relays it to the regions of the cerebral cortex concerned with motor responses to sensory information of that type
also cooperates with reticular formation in sleep/awake
some memory
2—one in each hemisphere
What is the amygdala?
anger—evolutionary advantage
fight with frontal lobe for control
Are the Nuclei of the hypothalamus protected by the blood–brain barrier?
no
What is the role of the hypothalamus?
regulates basic homeostatic functions
of the body
What is the suprachiasmatic nucleus (SCN)?
in the hypothalamus is the main generator of the biological clock that times our daily behavioral and metabolic rhythms
What can damage to the basal nuclei result in?
affect the planning and fine- tuning of body movements (e.g., Parkinson’s disease)
What is the limbic system composed of?
Parts of the thalamus, hypothalamus, and basal nuclei, along with other gray-matter centers (amygdala, hippocampus, and olfactory bulbs) form the “emotional brain” or limbic system
What is the cerebral cortex’s composition?
6 layers of neurons and is grey matter
What is the corpus callosum?
Thick bundles of axons (corpus callosum) connect the two cerebral hemispheres and coordinate their functions
Which hemisphere controls the right side of the body?
left hemisphere
What are the 4 regions in each hemisphere?
frontal, parietal, temporal, and occipital lobes
What is the somatosensory cortex?
A band across the parietal lobes (somatosensory cortex) registers touch, pain, temperature, and pressure
What is the primary motor cortex?
The primary motor cortex of the cerebral cortex runs in a band just in front of the somatosensory cortex.
Does size of the body part correlate to amount of area in brain?
no, Some body parts, such as lips and fingers, are represented by large regions – others, such as the arms and legs, are represented by relatively small regions
What is the premotor cortex?
frontal lobe controls skeletal muscles in coordinating complex movements
What is the posterior parietal cortex?
This area of the cerebral cortex is guided by sensory input received and processed by the posterior parietal cortex of the parietal lobe
What can damage to the premotor cortex or posterior parietal cortex result in?
inability to process complex sensory information to carry out movements in space, such as working with tools
What is the Prefrontal association cortex?
Prefrontal association cortex of the frontal lobe is the key part of the brain involved in thinking, such as planning for voluntary activity, decision making, and creativity, as well as for personality traits
What is the Parietal–temporal–occipital association cortex
Parietal–temporal–occipital association cortex integrates all sensory input, such as locating objects by sight, touch, and/or sound, and relating the parts of the body to the external environment
What is the Limbic association cortex?
Limbic association cortex of the temporal lobe is important for motivation, emotion, and memory
What is Wernicke’s area?
coordinates inputs from the visual, auditory, and general sensory association areas
What is Broca’s area?
oordinates the lips, tongue, jaws, and other structures producing the sounds of speech, and passes the program to the primary motor area
What is language? what is it composed of?
is a written or spoken form of communication used to convey ideas
Language involves integrating speaking ability (expression) and comprehension
What is memory?
storage and retrieval of a sensory or motor experience, or a thought
What is learning?
change in the response to a stimulus based on information or experiences stored in memory
What is consciousness?
awareness of ourselves and our surroundings, and an understanding of the significance and likely consequences of events that we experience
What is short-term memory?
stores information for seconds, minutes, or at most an hour or so – it involves transient changes in neurons that can be erased relatively easily
What is long-term memory?
stores information for days, years or a lifetime – it involves more or less permanent molecular, biochemical, or structural changes in interneurons
What can be erased is a person experiences a sudden fright, a blow, a surprise, or an electrical shock?
short-term memory
What is long-term potentiation?
increases the strength of synaptic connections in activated neural pathways following brief periods of repeated stimulation
Results in an increase in number of synaptic connections, and increased protein synthesis in interneurons
moves short term memory into long term memory
increases amount of receptors in response to the same stimulus (positive feedback)
What is the pathway for memory storage?
Information is input at the somatosensory cortex
The amygdala relays information to the limbic system
The hippocampus sends information to the frontal lobes, a major site of long-term memory storage
What are the 3 sequential mechanisms for learning?
- Storing memories
- Scanning memories when a
stimulus is encountered - Modifying the response to the stimulus in accordance with the information stored as memory
What is sensitization?
increased responsiveness to mild stimuli after experiencing a strong stimulus (e.g., sea hare experiments)
What does an EEG do?
Changes in neural activity (voltage changes) can be recorded by an electroencephalogram (EEG)
What is the range of human consciousness?
alert wakefulness to daydreaming, dozing, and sleep
Moving between states of consciousness involves changes in neural activity over the entire surface of the?
telencephalon
What does the EEG recored when an individual is fully awake?
pattern of rapid, irregular beta waves
What does the EEG recored when an individual’s mind at rest and eyes closed?
more regular alpha waves
What does the EEG recored when an individual is fully drowsy?
wave trains gradually become larger, slower, and less regular theta waves
What does the EEG recored when an individual transitions from drowsiness to deep sleep?
EEG patterns shift to even slower delta waves
hippocampus gets cleaned out = short term memory
What is REM sleep?
Periodically during deep sleep, the delta wave pattern is replaced by rapid, irregular beta waves characteristic of the waking state
Heartbeat and breathing rate increase, limbs twitch, and the eyes move rapidly behind the closed eyelids
How long does REM sleep last and what can occur during this time?
lasts 10-15 minutes, during which sleepers do most of their dreaming
What is the role of sleep?
sleep has restorative effects on mental and physical functions, the physiological basis is unknown
Which hemisphere is Broca’s area and Wenicke’s area located in?
left
What does lateralization mean?
occurs on only one side of the brain
What is the similarity between alpha and beta waves on an EEG?
they have the same frequency, but not the same amplitude
