Chapter 28: Nervous System Flashcards
Nervous System
the organ system that forms a communication and coordination network among all parts of an animal’s body
What are the 3 functions of the nervous system?
1) Sensory Input
2) Integration
3) Motor Output
Sensory Input
The conduction of signals from sensory receptors to integration centers
What are considered sensory receptors and integration centers?
Sensory Receptors: skin, nose, ears, etc.
Integration Center: Brain, spinal cord
Integration
Interpretation of sensory receptors and the formulation of the response
Motor Output
Conduction of signals from the integration centers to the effectors
Stimulus
any factor that causes a nerve signal to be generated (change in environment)
- changes membrane’s potential by opening it
Effectors
a cell, tissue, or organ capable of carrying out some action in response to a command from the nervous system
What are the two divisions of the nervous system?
1) Central NS
2) Peripheral NS
Central Nervous System
the integration and command center of the nervous system; the brain, and in vertebrates, the spinal cord
Peripheral Nervous System
the network of nerves and ganglia carrying signals into and out of the central nervous system
Nerve
A ropelike bundle of fibers thats tightly wrapped in connective tissue
Neurons
Basic unit of nervous system (nerve cell)
1) Sensory Neurons
2) Interneurons
3) Motor Neurons
Ganglia
a cluster of nerve cell bodies of the cells whose axons and dendrites make up nerves
Sensory Neurons
a nerve cell that receives info from sensory receptors and conveys signals into the central nervous system
Interneurons
a nerve cell, entirely within the central nervous systems, that integrates sensory signals and may relay command signals to motor neurons
- carry impulses up/down the spinal cord and brain
Motor Neurons
a nerve cell that conveys signals from the central nervous system to effector cells, such as muscle cells or gland cells
Cell Body
the part of a cell, such as a neuron, that houses the nucleus
Dendrites
a neuron fiber that conveys signals from its tip inward, toward the rest of the neuron; in a motor neuron, one of several short, branched extensions that convey nerve signals toward the cell body
- Short, numerous, highly branched
- Signals from sensory cell or interneuron
Axon
a single long neuron fiber that conducts signals to another neuron or to an effector cell
Supporting Cells
in the nervous system, a cell that protects, insulates, and reinforces a neuron (ex. Schwann cell)
Myelin Sheath
a series of cells, each wound around, and thus insulating, the axon of a nerve cell in vertebrates. Each pair of cells in the sheath is separated by a space called a node of Ranvier
Nodes of Ranvier
an unmyelinated region on a myelinated axon of a nerve cell, where signal transmission occurs
- Signals will jump from node to node → faster 150 m/sec
Synaptic Knob
the relay point at the tip of transmitting neuron’s axon, where signals are sent to another neuron or to an effector
Resting Neuron
Contains potential energy in form of difference of electrical charge
- used to send info from one part to another
Resting Potential
Voltage across the plasma membrane of a resting neuron
- Caused by the membrane keeping negatively charged dissolved proteins/large organic molecules inside the cell and channels/pumps (made of protein) that regulate passage of inorganic ions
Threshold Potential
Minimum change in a membrane’s collage that must occur to generate an action potential
- all or none effect
Sodium-Potassium (Na+ - K+) Pumps
a membrane protein that transports sodium ions out of, and potassium ions into, a cell against their concentration gradients. The process is powered by ATP.
- Na+ low inside the cell and K+ high inside cell
Action Potential
a self-propagating change in the voltage across the plasma membrane of a neuron; a nerve signal
What are the events of transmission of nerve signals?
Polarized –> stimulus –> depolarized/action potential –> repolarized
Synapse
Junction between two neurons or a neuron and its effector
- Electrical and chemical
Electrical (Synapse)
Direct connection b/w each axon and dendrite
- found where speed is crucial
Chemical (Synapse)
Common type w/ gap b/w axon and dendrite
- make chemical signals
Synaptic Cleft
a narrow gap separating the synaptic knob of a transmitting neuron from a receiving neuron or an effector cell (prevents action potential from spreading directly to receiving neuron)
Neurotransmitter
a chemical messenger that carries information from a transmitting neuron to a receiving cell, either another neuron or an effector cell
- dual role as hormone
Summation
the overall effect of all the information a neuron receives at a particular instant
Acetylcholine
a nitrogen-containing neurotransmitter; among other effects, it slows the heart rate and makes skeletal muscles contract
Biogenic Amines
a nitrogen-containing neurotransmitter that is derived from amino acids and important for the central nervous system to increase heart rate, sleep, mood, attention, learning
- epinephrines, norepinephrine
What are the 3 trends in evolution of brain?
1) Increase in size of brain
2) Subdivision of forebrain
3) Increase in interpretive power of cerebrum
4) Vertebrate develops
What are 3 patterns from evolution?
1) Cephalization
2) Centralization
3) Peripheral Division
Nerve Web
a web like system of neurons, characteristic of radially symmetrical animals such as Hydra
Cephalization
Formation of head, more bilateral symmetry
Centralization
Formation of brain/spinal cord
- CNS is distinct from PNS
Peripheral Division
Outside nervous system develops and ganglia/nerve cords are made along with cell bodies, axons, and dendrites
What are 3 protections of nerve tissue?
1) Bone (cranium and vertebrae)
2) Meninges
3) Cerebrospinal fluid
Spinal Cord
the dorsal hollow nerve cord in vertebrates, located w/in the vertebral column; with the brain, makes up the central nervous system
Brain
master control center that includes homeostatic centers that keep the body functioning smoothly, sensory centers that integrate data from the sense organs, and centers of emotions and intellect (exerts control over spinal cord and sends out own motor commands to muscles)
Blood Brain Barrier
a system of capillaries in the brain that restricts passage of most substances into the brain, thereby preventing large fluctuations in the brain’s environment
Ventricles
a space in the vertebrate brain, filled with cerebrospinal fluid
Cerebrospinal Fluid
blood-derived fluid that surrounds, protects against infection, nourishes, and cushions the brain and spinal cord
Meninges
layers of connective tissue that enwrap and protect the brain and spinal cord
What are the two distinct areas of the CNS?
1) White matter (axons/dendrites)
2) Gray matter (nerve cell bodies)
Cerebral Cortex
a folded sheet of gray matter forming the surface of the cerebrum, it contains integrating centers for higher brain functions such as reasoning, speech, and debate
Cranial Neves
signals to/from the brain
Spinal Nerves
in the vertebrate peripheral nervous system, a nerve that carries signals to or from the spinal cords
Sensory Division (PNS)
has two sets of neurons: one set brings in info about outside environment and other set supplies CNS w/ info about body itself
- Provides brain w/ sensations of pain → warning for body of tissue damage
Referred Pain
pain that issues form an internal organ but that is felt on the body surface
Motor Division (PNS)
- two parts: Somatic NS and Autonomic NS
Somatic Nervous System
the division of the motor nervous system of vertebrates composed of neurons that carry signals to skeletal muscles (voluntary)
Autonomic
a subdivision of the motor nervous system of vertebrates that regulates the internal environment; made up of sympathetic and parasympathetic subdivisions (involuntary)
Parasympathetic Division
one of two sets of neurons in the autonomic nervous system; generally promotes body activities that gain and conserve energy, such as digestion and reduced heart rate
Sympathetic Division
one of two sets of neurons in the autonomic nervous system; generally prepares the body for energy consuming activities, such as fleeing or fighting
What are the 4 major structures of the brain?
1) Cerebrum
2) Interbrain
3) Brainstem
4) Cerebellum
Cerebrum
Highest part of brain in terms of location and function
- Right hemisphere for nonverbal side
- Left hemisphere for verbal side
- corpus callosum
- cerebral cortex
Corpus Callosum
Big thick band of neurofibers that connect cerebral hemispheres
Cerebral cortex
The outer part of the brain, has ridges and grooves
Basal Ganglia
clusters of nerve cell bodies located deep within the cerebrum that are important in motor coordination
What are the 4 lobes of the cerebral hemispheres?
1) Frontal lobe (motor/speech cortex)
2) Parietal (sensory cortex)
3) Temporal (Auditory/Olfactory cortex)
4) Occipital (visual)
Association Cortex
All parts of lobes that are responsible for higher mental capabilities (thinking)
Interbrain
Thalamus…gatekeeper to cerebrum
- analyzes, sorts, and transmits sensory inputs
- suppresses some signals and enhances others
Hypothalamus…controls all its homeostatic mechanisms and glands/hormones
Brainstem
Sensory filter; selects which info goes into the higher center
- Mid Brain, pons, Medulla Oblongata
Mid brain
Relay Center for eyes, ears, and reflexes
Pons
Site where many cranial nerves enter/leave the brain
Medulla Oblongata
Respiratory Center, Cardiovascular Center, Reflect Center
Cerebellum
Mini-me of brain that has two highly folded hemispheres
- coordination of voluntary muscles, maintain balance/equilibrium, regulate muscle tone
Brain Waves
Electrical activity in brain
- results forma action potentials firing in brain neurons
- alpha waves, beta waves, delta waves, REM Sleep
Reticular Formation
functional system of neurons that extends from the medulla oblongata thru brainstem to thalamus and receives data from sensory receptors
Limbic System
a functional unit of several integrating and relay centers located deep in the human forebrain; interacts with the cerebral cortex in creating emotions and story memories
Amygdala
an integrative center of the cerebrum; functionally the part of the limbic system that seems to label info to be remembered
Hippocampus
an integrative center of the cerebrum; functionally, part of the limbic system that plays central roles in memory and learning
Long Term Depression
a reduced responsiveness to an action potential (nerve signal) by a receiving neuron
Long Term Potentiation
an enhanced responsiveness to an action potential (nerve signal) by a receiving neuron
