ch. 49 Flashcards
what do all animals have
a nervous system
cnidarian examples
jellyfish, hydras, anemones
nervous system of cnidarians
- nerve net
- neurons connected to each other in network
- activation of neurons in one area lead to activation of all or most neurons
simplest of nervous systems
nerve net
nervous system of echinoderms
- nerve ring around mouth connected to larger radial nerves extending to arms
- mouth and arms operate independently
nervous system of planaria
- nerve cords extend by length of animal connected by transverse nerves
- collection of neurons in head form cerebral ganglia
- perform basic integration of sensory input and motor output
nervous system of annelids
- same basic structure as planaria
- more neurons
- ventral nerve cords have ganglia in each segment
- rudimentary brain
nervous system of simple mollusks
- similar to annelids
- pair of anterior ganglia
- paired nerve cords
cephalization
increasingly complex brain in head
brain of drosophila
several subdivisions with separate functions
brain of advanced mollusks
brains with well-developed subdivisions
glial cells/glia function
nourish, support, and regulate neurons
what do embryonic radial glia form
tracks along which newly formed neurons migrate
astrocytes
participate in formation of blood-brain barrier
blood-brain barrier
restricts entry of most substances into the brain
what can radial glial cells and astrocytes both act as
stem cells
where does the CNS develop from
hollow dorsal nerve cord
what does the cavity of the nerve cord give rise to
narrow central canal of the spinal cord and ventricles of the brain
what are the spinal canal and ventricles filled with
cerebrospinal fluid
cerebrospinal fluid
supplies CNS with nutrients and hormones, carries away waste
gray matter
- neuron cell bodies
- dendrites
- unmyelinated axons
white matter
- bundles of myelinated axons
what does the spinal cord do
- convey info to/from brain
- generate basic pattern of locomotion
- produces reflexes independently of the brain
reflex
body’s automatic response to a stimulus
function of PNS
- transmit info to/from CNS
- regulates movement and internal environment
afferent neurons in PNS
transmit info to CNS
efferent neurons in PNS
transmit information away from CNS
divisions of autonomic nervous system
- sympathetic
- parasympathetic
- enteric
2 efferent components of CNS
autonomic nervous system and motor system
motor system
carries signals to skeletal muscles and can be voluntary
autonomic nervous system
regulates smooth and cardiac muscles, generally involuntary
enteric nervous system
exerts direct control over the digestive tract, pancreas, and gallbladder
sympathetic division
regulates arousal and energy generation (fight/flight)
parasympathetic division
antagonistic effects of sympathetic on target organs
- promotes calming and return to rest/digest functions
functions of parasympathetic divison
- constricts eye pupil
- stimulates salivary gland secretion
- constricts bronchi in lungs
- slows heart
- stimulates activity of stomach/intestines/pancreas
- stimulates gallbladder
- promotes emptying of bladder
- promotes erection of genitalia
3 major regions of vertebrate brain
- forebrain
- midbrain
- hindbrain
forebrain
- processing of olfactory input, regulation of sleep, learning, and any complex procesing
midbrain
coordinates routing of sensory input
- receives and integrates sensory information and sends in to specific regions of the brain
hindbrain
controls involuntary activities and coordinates motor activities
what does the difference in size of particular brain regions among vertebrates show
relative importance of particular brain function
how many neurons and synapses in the human brain
- 100 billion neurons
- 100 trillion connections
anterior neural tube
gives rise to the forebrain, midbrain, and hindbrain during embryonic development
what form the brainstem?
midbrain and part of the hindbrain
where is the brainstem
joins with spinal cord at base of brain
what does the rest of the hindbrain give rise to
cerebellum
what does the forebrain divide into
- diencephalon
- telencephalon
diencephalon
forms endocrine tissues in brain