chap 12 nervous system Flashcards
metazoans
any of a group (Metazoa) that comprises all animals having the body composed of cells differentiated into tissues and organs and usually a digestive cavity lined with specialized cells.
do sponges aka parazoa have a nervous sys?
no but they do have sensory primordia
describe the nerve network of the radiata?
cobweb-like nerve network encircling the mouth.
It projects most densely into tentacles (or comb rows) and aboral surface.
define bilaterian and giv ex
symmetry is a characteristic of certain organisms in which there is regularity in parts on a plane or around an axis.
ex: humans
metameric
relating to or consisting of several similar segments
the body and the nervous system of the bilaterias are
metameric
cephalization
forming head and anus
Annelida (segmented worms) have a nervous system consisting of
ventral nerve cord that travels the length of the body
ganglia, one in each segment (metamere)
nerve collar surrounding the pharynx
arthropods are
invertebrate animals (such as insects, arachnids, and crustaceans)
arthropod cephalic ganglion has what kind of brain
a true brain that is quite complex, allowing
learning complex navigation
memory
Cephalopoda (octopods and squids) have complex brains that allow
solve complex problems like opening pill bottles
and show evidence of cognition
learn and memmory storage
dominant eye
2/3 of neurons in arm which causes each arm to act independently and may have nocireceptors that may signal pain
name the 3 types of chordata and which one has most complex brain?
Cephalochordata (lancelets)
Urochordata (tunicates)
Vertebrata (vertebrates)
vertebrates have the most complex brain
grey matter
-neuron bodies and dendrites
external to white matter in the brain
comprises the brain’s cortex (outer layer)
cerebral cortex houses neurons performing higher brain functions
4 regions of the vertebrate brain
forebrain: telencephalon (cerebral hemispheres) diencephalon (thalamus and hypothalamus)
mesencephalon
(midbrain)
rhombencephalon
(hindbrain)
4 regions of the vertebrate brain
forebrain:
telencephalon
(cerebral hemispheres)
diencephalon
(thalamus and hypothalamus)
mesencephalon
(midbrain) will control processing of auditory and visual movement
rhombencephalon
(hindbrain) of the medulla oblongata, the pons, and the cerebellum.
proto
original or primitive
Protoreptilian” brain
dervied from rhombencephalon and mesencephalon
has: brain stem pons medulla oblongata controls basic homeostatic processes (heartbeat, breathing, etc.)
Paleomammalian” brain (limbic system)
derived from mesencephalon, diencephalon and telencephalon olfactory bulbs thalamus hypothalamus hippocampi amygdalas involved in a variety of processes (olfaction, emotion, behavior, long-term memory, etc.)
Paleomammalian” brain (limbic system)
derived from mesencephalon, diencephalon and telencephalon olfactory bulbs thalamus hypothalamus hippocampi amygdalas involved in a variety of processes (olfaction, emotion, behavior, long-term memory, etc.)
seeks pleasure and avoid pain
neocortex
derived from the telencephalon it is essentially an outgrowth of the limbic system comprises the cerebral cortices controls higher cognitive functions language reason about external world
the reptilian brain is now what of humans had this rumor been true
basal ganglia which is not only part of mammals brain
paul mcclain believes that there is 3 parts and that they are all part of the brain like if we start arguing, that is the reptilian part
somatotopic maps.
Sensory processes are maintained in topographic maps in the brain
Somatotopy
point-for-point correspondence of an area of the body to a specific point on the central nervous system
which brain has more neurons? humans or insects?
humans have billions of neurons because our brains are bigger
insects have thousands
brain homoculus
the the relative sensory space human body parts occupy on the cerebral cortex.
ex: visual or motor cortex are in a certain region
do birds have a neocortex
no but they do have a the avian dorsal ventricular ridge (DVR), also derived from the telencephalon, contains nuclei (neuron clusters) that appear to function as neocortical neurons do.
unique about birds brains
Many bird species have impressive cognitive abilities.
Birds have higher forebrain neuron density than mammals.
crow uses short stick to get the stones that will later drop in tube and open the box to get the long tube which will complete total of 8 steps for the first time to get the food that he wants to eat
Primates, and possibly in other mammals, have specialized mirror neurons located
in the primary motor cortex of the cerebrum.
motor neurons are activated when?
when the animal generates a particular movement,
such as reach and grasp
when the animal sees another individual perform a movement
The neuron “mirrors” the behavior of other individual’s action and neuronal activity.
mirror neurons are beneficial when trying to understand movement because?
Mirror neurons appear to code for the abstract concept of the movement,
not just the execution of the movement.
chordata
present during some time of their life cycles are a notochord, a dorsal hollow tubular nerve cord, pharyngeal slits, endostyle/thyroid gland, and a post-anal tail.
Cephalochordata (lancelets) vs
Urochordata (tunicates)
Tunicates are sessile as adults. Lancelets retain the juvenile swimming form of tunicates into adulthood via neotony. Probably happened as a result of some tunicates settling down in the ocean near river mouths and would get suffocated eventually by silt
neuron circuits
- a closed loop network providing a return path for current.
- can elicit a coordinated response in an animal’s effectors.
The vertebrate spinal cord has two types of circuits:
- local
2. ascending/descending
local circuits are
reside within a single spinal cord segment
e.g., simple spinal reflex circuit
relatively primitive
ascending
send information
from spinal cord to brain
descending
send information
from brain to spinal cord
cranial nerves
peripheral nerves
that connect directly to the brain.
Cranial nerves may be made up of sensory neurons autonomic (involuntary) motor neurons somatic (voluntary) motor neurons combinations of both sensory and motor neurons
spinal nerves
are peripheral nerves that connect to the spine.
Input from sensory neurons enters via
dorsal root
Output to motor neurons exits via the
ventral root
when saying that Neuronal connections in the CNS are not “hardwired”.
it means that Connections between neurons adapts to the animal’s experience during
juvenile development
maturation
learning experiences
nerve
a bundle of neuron axons in the PNS that convey information
from a particular source
enteric nervous system
one of the main divisions of the autonomic nervous system (ANS) and consists of a mesh-like system of neurons that governs the function of the gastrointestinal tract.
It appears in the earliest eumetazoans, and is the most primitive nervous sytem.
indep of CNS and called second brain
Autonomic Nervous System (ANS)
controls CONSTANT involuntary functions that can change depending on what is on control of that moment like is it sympathetic or parasympathetic
have ganglia instead of motor neurons
neuromuscular junction.
The point of synaptic contact for somatic motor neurons are
Each muscle fiber is innervated by how many motor neurons?
1
One motor neuron may synapse onto how many muscle fibers?
multiple muscle fibers.
sympathetic originated where?
in thoracolumnar (btwn thoracic and lumbar)
parasympathetic originated where?
sacral spinal cord
cranial
above and below sympathetic
ganglia away from spinal cord b/c it works more with organs
post ganglia are shorter than preganglia
sympathetic has power to
quickly coordinate the functions of many organs at once
ganglia found near spine for wide contact to trigger excitatory ap
preganglia are shorter than postganglia
sympathetic has power to
quickly coordinate the functions of many organs at once to trigger fast response at once
ganglia found near spine for wide contact to trigger excitatory ap
preganglia are shorter than postganglia
autonomic nervous system controls
smooth and cardiac muscle; glands (autonomic/internal effectors)
pacemaker region of the heart and some other cardiac tissue
exocrine glands (empty products out of the body)
some endocrine glands
acid-secreting cells of the stomach
brown adipose tissue metabolism
fish swim bladder
fish, amphibian, some reptile chromatophores
eumetazoan
include true tissues organized into germ layers, and an embryo that goes through a gastrula stage.
except sponges, placozoa, and several other obscure or extinct life forms, such as Dickinsonia.
y is enteric sys indep of CNS and called second brain?
neurons in the enteric nervous system enables us to “feel” the inner world of our gut and its contents. Much of this neural firepower comes to bear in the elaborate daily grind of digestion. Breaking down food, absorbing nutrients, and expelling of waste requires chemical processing, mechanical mixing and rhythmic muscle contractions that move everything on down the line.
acts as reflex as well
