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Neurons and Nervous System
Terms in this set (67)
In simple animals such as sponges; is composed of neurons in contact with one another and with contractile cells in the body wall
Ladderlike Nervous System
Planarians have a __________ ____________ ____________, with two ventrally located lateral or longitudinal nerve cords (bundles of nerves) that extend from the cerebral ganglia to the posterior end of their body
A concentration of neurons and sensory receptors in a head region
A cluster of neurons is called a _______, and the anterior cerebral "these" receive sensory information from photoreceptors in the eyespots and sensory cells in the auricles
Central Nervous System
Consists of a spinal cord and brain; develops from an embryonic dorsal neural tube. The spinal cord is continuous with the brain because the embryonic neural tube becomes the spinal cord posteriorly, while the vertebrate brain is derived from the enlarged anterior end of the neural tube
Most ancient part of the brain. Nearly all vertebrates have a well-developed _________ that regulates motor activity below the level of consciousness.
The optic lobes are part of the __________, which was originally a center for coordinating reflexes involving the eyes and ears
Starting with the amphibians and continuing in the other vertebrates, the ________ processes sensory information. Originally, it was concerned mainly with the sense of smell. Later, the thalamus evolved to receive sensory input from the midbrain and the hindbrain and to pass it on to the cerebrum
Highly developed in mammals; integrates sensory and motor input and is particularly associated with higher mental capabilities.
Outer layer of the cerebrum; extremely large and complex
Human Nervous System
Has three specific functions:
1) Receives sensory input
2) Performs integration (the CNS sumps up the input it receives from all over the body
3) Generates motor output
Peripheral Nervous System
Consists of all the nerves and ganglia that lie outside the central nervous system. The paired cranial and spinal nerves are part of the _______. Somatic nervous system has sensory and motor functions that control the skeletal muscles
Also known as nerve cells, these are the functional units of the nervous system. They receive sensory information, convey the information to an integration such as the brain, and conduct signals from the integration center to effector structures such as the glands and muscles.
Serve as supporting cells, providing support and nourishment to the neurons
Contains a nucleus and a variety of organelles
Short, highly branched processes that receive signals from the sensory receptors or other neurons an transmit them to the cell body
This is the portion of the neuron that conveys information to another neuron or to other cells.
Axons can be bundled together to form nerves. For this reason, axons are often called _______ ________.
Take nerve impulses from the CNS to muscles or glands. They are said to have a multipolar shape because they have many dendrites and a single axon. They also cause muscle fibers to contract or glands to secrete, and therefore they are said to innervate these structures
Occur entirely within the CNS. Are typically multipolar in shape and convey nerve impulses between various parts of the CNS.
Time during which an axon is not conducting an impulse
Rapid change in polarity across a portion of an axonal membrane as the nerve impulse occurs
The action potential "jumps" from node to node across the myelin sheath
The sodium ion gates are unable to open as soon as an action potential has moved on
Excites skeletal muscle but inhibits cardiac muscle. Has either an excitatory or inhibitory effect on smooth muscle or glands, depending on their location
Important to dreaming, waking, and mood
Involved in emotions, learning, and attention
Involved in thermoregulation, sleeping, emotions, and perception
Breaks down acetylcholine
Molecules that block the release of a neurotransmitter or modify a neuron's response to a neurotransmitter.
Summing up of excitatory and inhibitory signals
Three protective membranes that wrap the brain and spinal cord
Cushions and protects the CNS
Contains cerebrospinal fluid; are interconnecting spaces that produce and serve as reservoirs for cerebrospinal fluid
Bundle of Nervous tissue enclosed in the vertebral column; extends from the base of the brain to the vertebrae below the rib cage. Has 2 main functions: center for reflex actions, and provides a means of communication between brain and spinal nerves
Consists of cell bodies and unmyelinated fibers. Is shaped like a butterfly, or the letter H. Contains portions of sensory neurons and motor neurons, as well as short interneurons that connect sensory and motor neurons
Contains four interconnected chambers called ventricles.
Largest portion of the brain in humans. Last center to receive sensory input and carry out integration before commanding voluntary motor responses.
Each receives information from and controls the opposite side of the body
Lie posterior to the frontal lobe and are concerned with sensory reception and integration, as well as taste.
Located laterally. A primary auditory area here receives information from our ears
The most posterior lobe.
A thin but highly convoluted outer layer of gray matter that covers the cerebral hemispheres.
Primary Motor Area
In the frontal lobe just ventral to the central sulcus. Voluntary commands to skeletal muscles begin here, and each part of the body is controlled by a certain section
Primary Somatosensory Area
Just dorsal to the central sulcus in the parietal lobe. Sensory information from the skin and skeletal muscles arrives here, where each part of the body is sequentially represented in a way similar to the primary motor area
Masses of gray matter that are located deep within site matter; integrate motor commands, ensuring that proper muscle groups are activated or inhibited
A region that encircles the third ventricle; the hypothalamus and thalamus are here.
Forms the floor of the third ventricle. It is an integrating center that helps maintain homeostasis by regulating hunger, sleep, thirst, body temperature, and water balance
Consists of two masses of gray matter located in the sides and roof of the third ventricle. It is on the receiving end for all sensory input except smell
Secretes the hormone melatonin; located in the diencephalon
Largest part of the hindbrain and has two portions; each is primarily composed of white matter
Contains the midbrain, the pons, and the medulla oblongata
Acts as a relay station for tracts passing between the cerebrum and the spinal cord or cerebellum
Contains bundles of axons traveling between the cerebellum and the rest of the CNS. Functions with the medulla oblongata to regulate breathing rate, and has reflex centers concerned with head movements
Contains a number of reflex centers for regulating breathing, heartbeat, and blood pressure. Also contains the reflex centers for vomiting, coughing, sneezing, hiccuping, and swallowing
Complex network of tracts and nuclei that incorporates medial portions of the cerebral lobes, the basal nuclei, and the diencephalon. Blends higher mental functions and primitive emotions into a united whole
The ability to hold a thought in mind or recall events from the past
An enhanced response at synapses seen particularly within the hippocampus
Some are sensory nerves, she are motor nerves, and others are mixed nerves. Largely concerned with the head, neck, and facial regions of the body.
Emerge from the spinal cord by two short branches, or roots. The dorsal root contains the axons of sensory neurons, which conduct impulses to the spinal cord from sensory receptors
Dorsal Root Ganglion
Cell body of a sensory neuron
In this system, the nerves serve the skin, joins, and skeletal muscles. Therefore, the system includes nerves that take sensory information to the CNS, and motor commands away from the CNS to the skeletal muscles
Generate nerve impulses that move along sensory axons through a dorsal root ganglion toward the spinal cord
Nerve impulses travel along motor axons to a(n) _________, which brings about a response to a stimulus, such as stepping on a pin
In the PNS, it regulates the activity of cardiac and smooth muscle and glands; it carries out its duties without our awareness or tin tent. Divided into sympathetic and parasympathetic divisions
Especially important during emergency situations and is associated with "fight or flight." If you need to fend off a foe or flee from danger, this division supplies you with a ready supply of glucose
This division is often referred to as the craniosacral portion of the autonomic system. Sometimes called the "housekeeper" or "rest and digest division;" promotes digestion of food, slows the heartbeat, and contracts the pupil. USES ACETYLCHOLINE
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