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