Nervous System Flashcards
Major controlling, regulatory, and communicating system in the body. What is this?
Center of all mental activity. What are the three of these that it involves?
Nervous system
- Thought
- Learning
- Memory
The nervous system is responsible for maintaining homeostasis along with what other system?
What is the nervous system composed of? (4)
- Endocrine system
- brain, spinal cord, nerves, and ganglia
The constant internal environment that must be maintained for the cells of the body. The nervous system helps maintain this by regulating vital functions (body temperature, heart rate, breathing), and responding to internal and external stimuli.
Homeostasis
Function of nervous system. Is information that is gathered from stimuli, converted into nerve impulses, and transmitted to the brain.
Sensory input (sensory functions)
Function of nervous system. Decisions are made on the basis of the sensory input.
Integrative functions
Functions of nervous system. This is part of nervous system that responds to sensory input and integration. Sends signals to effectors
Motor functions
Causes an effect in response to directions from the nervous system. In muscles, it causes them to contract.
Motor signals travel away from the brain, motor output travels away from the brain, and motor impulses stimulate these along with muscles or glands that cause an effect.
Effectors
What are the 2 subdivisions of the nervous system?
CNS and PNS
What is protected by the cranium?
What is protected by the vertebral column?
- Brain
- Spinal cord
Bundles of nerve fibers the extend from the CNS to peripheral organs ( ex. muscles and glands). Include cranial nerves and spinal nerves.
Nerves
Cranial nerves has how many pairs? What about spinal nerves?
-12
-31
What 2 nerves consist of motor and sensory fibers?
cranial nerves and peripheral nerves
What nerves arise form the brain? What other nerves arise from the spinal cord?
- cranial nerves
- peripheral nerves
Collections of nerve cell bodies outside the CNS. These are the areas where nerve cell bodies are joined into small knots known as this.
Ganglia (singular form is ganglion)
Transmits impulses from peripheral organs to the CNS. Nerve impulses that travel towards the brain (sensory input) are known as this.
It my be helpful to remember that sensory input affects the nervous system
Afferent (sensory) division
Transmits impulses from the CNS to peripheral organs. This causes an affect or action.
Efferent (motor) division
Efferent division is subdivided into what? (2)
Somatic nervous system and Autonomic nervous system (ANS)
Supplies motor impulses to skeletal muscles. Permits conscious control of the skeletal muscle.
Somatic nervous system (voluntary control)
Supplies moto impulses to cardiac muscle, smooth muscle, and glandular epithelium. Includes motor fibers to the heart, organs, and glands that are not under voluntary conrol.
Autonomic nervous system (ANS)
What system is subdivided into sympathetic and parasympathetic divisions?
Autonomic nervous system (ANS) (involuntary control)
What are two types of cells in nerve tissue?
What is the nerve cell that transmits impulses?
What are nonconductive cells that provide a support system for neurons?
- Neuron and Neuroglia
- Neuron
- Neuroglia
Composed of conducting cells (neurons), which are long and thin, embedded in a matrix of supportive cells (neuroglia).
Nerve tissue
Are amitotic. Do not undergo mitosis. If this is destroyed, it cannot be replaced.
Neurons
Cell body of a neuron. Main part of the neuron and contains a nucleus.
Soma
Cytoplasmic extensions that are short and branching transmit impulses to the cell body
One or more dendrites
Cytoplasmic extension that is elongated. Carries impulses away from the cell body.
A single axon
One or more side branches of an axon
Axon collateral
Short branches at the distal end of an axon or axon collateral
Telodendria
An enlargement at the distal end of telodendria. Contains vesicles of neurotransmitters.
Synaptic knob
White fatty substance that surrounds nerve fibers. Is like an insulator.
Myelin (myelin sheath)
What makes up white matter in the CNS?
What two fibers make up gray matter in the CNS?
- Myelinated fibers
- Cell bodies and unmyelinated fibers
Short, unmyelinated regions between two segment of myelin in myelinated nerve fiber
Nodes of Ranvier
In the peripheral nervous system, myelin is produced by what cells that make up the neurilemma?
In the central nervous cells, what produces myelin?
In what nervous system can damaged nerves regenerate?
-Schwann cells
- oligodendrocytes
- peripheral nervous system
Consists of a layer of Schwann cells that surrounds a neve fiber in the PNS. Produces myelin that surrounds axons in the PNS. Plays a role in regeneration of nerve fibers.
Neurilemma
Neuroglial cells that produce myelin that surrounds axons within the CNS. What is this?
What is not located in the CNS?
Because this is not located in the CNS, fibers do not what?
- Oligodendrocytes
- Neurilemma
- regenerate
What carry impulses from peripheral sense receptors to the CNS. Have long dendrites and short axons.?
What neurons transmit impulses from the CNS to effector organs, such as muscles and glands. Have short dendrites and long axons.?
- Afferent (sensory) neurons
- Efferent (motor) neurons
Form the connecting link between the afferent and efferent neurons. Located within the CNS. Are located in the spinal cord and brain. They are connecting neurons. Have shot dendrites and a short or long axon.
Interneurons (association neurons)
Do not conduct nerve impulses. Support, nourish, and protect neurons. Are capable of mitosis. What is this?
What are some examples?
What are the most abundant glial cells?
Neuroglia
- Schwann cells, oligodendrocytes
- astrocytes (star-shaped)
Cell membrane of a nonconducting neuron. Impermeable to passive diffusion of sodium (NA+) and potassium (K+) ions.
Resting Membrane
Resting membrane. What are excitable (able to respond to stimuli) and can conduct impulses? This forms the basis of all functions associated with the nervous system.
What two things are maintained on different sides of a neuron’s resting membrane?
If diffusion is possible, the concentration of ions of sodium or potassium gradually what on both sides of a membrane?
When the membrane is impermeable, there can be a difference in the concentration from one side of the membrane to the other. What is this called?
Neurons
- Sodium and potassium
- equalizes
- concentration gradient
Active transport mechanism. Maintains a difference in concentration of Na+ and K+ on the two sides of the membrane. What is this?
- What ions are concentrated in extracellular fluid?
- What ions are inside the cell?
What does this result in?
What charges are outside the cell?
What charges are inside the cell?
- Sodium-potassium pump
- Sodium ions
- Potassium ions
- Polarized membrane
- Positive charges
- Negative charges
Difference in charges on the two sides of the resting membrane
Resting membrane potential
Event that alters the neuron cell membrane. Allows it to become permeable to sodium ion. Na+ ions diffuse into the cell.
Stimulus
As the positive Na+ ions enter the cell, the inside of the membrane becomes more positively charged.
Depolarization
For just an instant, an influx of sodium ions reverses the membrane polarity. More positive charges inside the cell than outside.
Reverse polarization
Very quickly, the membrane again becomes impermeable to sodium. Membrane becomes permeable to potassium ions for fraction of a millisecond. Potassium diffuses to outside of the cell, removes intracellular positive charge and restores resting membrane potential.
What is this?
What is the resting membrane potential?
Repolarization
- -70 millivolts
Rapid sequence of events in response to a stimulus (depolarization, reverse polarization, and repolarization)
Action potential
Minimum stimulus necessary to initiate an action potential.
Threshold stimulus
Answer the following:
- Where are sodium ions during the resting membrane outside or inside cell?
- Where are sodium ions during depolarization?
- Where are sodium ions during reverse polarization, inside or outside the cell?
- Where are sodium ions during repolarization?
- What happens if a stimulus is less than the threshold stimulus?
- Outside the cell
- Entering the cell
- Inside the cell
- pumping out of the cell
- Nothing
Causes a localized area of reverse polarization on the membrane. IN that one area the membrane is negative on the outside and positive on the inside.
- Creates a current flow
- Depolarizes the second point
-Continues point by point in domino fashion along the entire length of the neuron
- Creates a propagated action potential or nerve impulse
Threshold stimulus (propagated action potentials)
In myelinated fibers, depolarization occurs only at the places where there is no myelin. Which is where? Action potential “jumps”.
What is this?
Nodes of Ranvier (saltatory conduction)
Period of cell membrane “recovery”.
Refractory period
Permeable to sodium ions. Cannot respond to second stimulus.
Absolute refractory period
Stronger than normal stimulus required
Relative refractory period
Nerve impulse travels along a nerve fiber until it reaches the end of the axon. Must be transmitted to next neuron.
Conduction Across a Synapse
Region of communication between two neurons.
What is this?
What are the three parts of a synapse?
Synapse
- Synaptic knob
- Synaptic cleft
- Postsynaptic membrane
Neuron preceding the synapse
Presynaptic neuron
Neuron following the synapse
Postsynaptic neuron
Tiny bulges at the end of the telodendria on the presynaptic neuron.
Synaptic knobs
Small sacs within the synaptic knobs. Contain chemicals known as neurotransmitters (e.g. acetylcholine)
Synaptic vesicles
Small space between the synaptic knob of a neuron and the cell membrane of an adjacent neuron
Synaptic cleft
When a nerve impulse reaches the synaptic knob. Series of reactions releases neurotransmitters into the synaptic cleft. Neurotransmitters diffuse across synaptic cleft. React with receptors on the postsynaptic cell membrane. Transmitters are quickly inactivated by enzymes. What is this? What are examples?
Synaptic transmission
- cholinesterase inactivates acetylcholine
Billions of neurons in the CNS are organized into functional groups. Arranged in pathways, or circuits.
What is this? What are the functions?
- Neuronal Pools
Functions: - Receive information
- Process and integrate that information
- Transmit it to some other destination
A type of conduction pathway. Impulses can only travel in one direction. What is this? What are the 5 components?
Reflex Arcs
- Receptor
- Sensory neuron
- Center
- Motor neuron
- Effector
An automatic, involuntary response o some change. Either inside or outside the body. Helps to maintain homeostasis, makes adjustments to heart rate, breathing rate, blood pressure.
What is this?
What is this also involved in (examples)?
- Reflex
Coughing, sneezing, reactions to painful stimuli, reflexes operate through the spinal cord and do not require input from the conscious brain.
Includes brain and spinal cord. Consists of gray and white matter. Enclosed in bone for protection. What is this? Where is it located?
CNS
- located in dorsal body cavity
Neuron cell bodies and unmyelinated fibers. What is this?
Myelinated fibers. What is this?
- Gray matter
- White matter
Connective tissue membranes that surround the brain and spinal cord.
Meninges
Outer layer. Tough, white fibrous connective tissue. Contains channels (dural sinuses). They provide a channel for the circulation of cerebrospinal fluid, which also cushions the brain and spinal cord.
Dura mater
Collect venous blood to return it to the cardiovascular system. Contained in the dura mate collect venous blood in the head instead of in the large veins.
Dural sinuses
Middle layer. Resembles a cobweb. Thin layer with numerous threadlike strands. Has a subarachnoid space.
Arachnoid
Space under the arachnoid
Subarachnoid space
Innermost layer. Thin, delicate membrane. Tightly bound to surface of brain and spinal cord.
Pia mater
Largest part of the brain. controls thinking, memory, personality, voluntary movement, and interpretation of sensation.
Cerebrum
Divides cerebrum into two cerebral hemispheres.
Longitudinal fissures
Bad of white fibers that connects cerebral hemispheres. Provides a communication pathway between the two halves
Corpus callosum
Convolutions (meaning it has many folds and creases) on the surface of the cerebrum.
Gyri
Grooves that separate gyri
Sulci
Controls motor functions as well as reasoning, intelligence, personality, behavior.
Frontal lobe
Motor speech is controlled primarily by this in the frontal lobe.
Broca’s area
The center for sensory functions is located here.
Parietal lobe
Understanding of language is primarily located in Wernicke’s area, here.
Temporal lobe
Lies deep within lateral sulcus. Is covered by parts of the frontal, parietal, and temporal lobes.
Insula
Outermost portion of cerebrum. Consists of gray matter. Center for sensory functions. Center for motor functions.
What is this?
What does this function in?
Cerebral cortex
- Memory
- Language
- Reasoning
- Intelligence
- Personality
What matter makes up the bulk of the cerebrum? Forms communication pathways int he cerebrum.
Where is this located?
- White matter
- Just beneath the cerebral cortex
Includes the thalamus, hypothalamus, and epithalamus.
Diencephalon
Is the largest part of the diencephalon. At the level of this, a person knows that he or she is experiencing sensation without being able to localize it. Relay station for sensory impulses going to the cerebral cortex. Channels the impulses to the appropriate region of the cortex for interpretation.
Thalamus
Located below the thalamus.
Regulates and integrates the ANS. Regulates emotional responses and behavior. Regulates body temperature. Regulates food intake. Regulates water balance and thirst. Regulates sleep-wake cycles. Regulates secretion of hormones from pituitary glands.
Serves as a connection between the central nervous system and the endocrine system.
Hypothalamus
What extends from the floor of hypothalamus to pituitary gland and acts as a connector between the two structures?
Infundibulum
Two “bumps” on posterior portion of hypothalamus. Involved in memory and motional responses to different odors.
Mammillary bodies
Pineal gland extends from posterior margin of this. Involved with onset of puberty. Regulates rhythmic cycles in body (biological clock)
Epithalamus
Superior portion of the brainstem.
Midbrain
Bundles of myelinated fibers. Contain voluntary motor tracts that descend from cerebral cortex.
Cerebral peduncles
Made up of superior and inferior colliculi.
Corpora quadrigemina
What are the visual reflex centers of the corpora quadrigemina?
What are the auditory reflex centers of the corpora quadrigemina?
- Superior colliculi
- Inferior colliculi
Narrow channel floor of CSF. Descends through the center of the midbrain.
Cerebral aqueduct
Middle portion of brain stem. Means bridge. Four cranial nerves arise here. Consist of nerve fibers. Form conduction tacts between higher brain centers and spina cord. Contains the pneumotaxic and apneustic areas
Pons
What doe the pneumotaxic and apneustic areas do?
help regulate breathing movements
Inferior portion of brain stem. Consist of ascending (sensory) and descending (motor) nerve fibers that connect brain and spinal cord. Consist of cardiac center, vasomotor center, respiratory center, and centers involved in coughing, sneezing, swallowing, and vomiting
Medulla oblongata
What adjusts heart rate and contraction strength?
What regulates blood pressure?
What regulates rate, rhythm, and depth of breathing?
- Cardiac center
- Vasomotor center
- Respiratory center
Second largest portion of brain. Two cerebellar hemispheres connected by the vermis. Consists of white matter.
What is this?
White matter is surrounded by a thin layer of gray matter which is what?
What are the branching arrangement of white matter?
- Cerebellum
- Cerebellar cortex
- Arbor vitae
Myelinated nerve fibers form communication pathways between cerebellum and other parts of the CNS.
Cerebellar peduncles
What mediates subconscious contractions of skeletal muscles for coordination, posture, and balance (this responds to impulses from the semicircular canals of the ear and maintains body balance and posture)?
Cerebellum
Fluid-filled cavities in the brain that are interconnected. What is this? What 3 ventricles does this include?
Ventricles
- lateral ventricles
- third ventricle
- fourth ventricle
Fluid that fills the cavities of the ventricles. Provides support and protection for the CNS, help to nourish the brain, maintains constant ionic conditions for brain and spinal cord, and provides a pathway for removal of waste products. Produced in the lateral ventricles and circulates through the third and fourth ventricles to the cerebral aqueduct and central canal of the spinal cord and throughout the subarachnoid layer of the meninges.
Cerebrospinal fluid (CSF)
What extends from foramen magnum (base of skull) to level of first lumbar vertebra? What is the distance in inches of this?
Surrounded by bone, meninges, and CSF. Meninges extend beyond the end of the spinal cord down to upprt part of the what?
How many segments is the spinal cord divided into? Each segment gives rise to a pair of what nerves?
Spinal cord (distance of 17 to 18 inches)
- sacrum
- 31 segments, spinal nerves
Spinal cord cross section is partially divides cord into right and left halves. What 2 things is it divided into?
What white matter surrounds gray matter and resembles a butterfly or letter H?
- Dorsal median sulcus and ventral median fissure
- Peripheral white matter
Spinal cord cross section. Each side of fray matter divided into dorsal, lateral, and ventral horns. Contains what 3 things?
- Terminal portions of sensory neuron axons
- Interneurons
- Dendrites and cell bodies of motor neurons
Central connecting bar between two large areas of gray matter. Surrounds central canal and contains CSF.
Gray commissure
Divides surrounding white mater into three regions on each side. What is this? Regions are dorsal, lateral, and ventral columns containing longitudinal bundles of myelinated nerve fibers known as what?
- Gray matter
- nerve tracts
Functions of the spinal cord. Conduction pathway for impulses going to and from the brain. These carry sensory impulses from body parts to the brain
Ascending tracts
Functions of the spinal cord. Carry motor impulses from the brain to muscles and glands.
Descending tracts
Responses to stimuli that do not require conscious thought–occur more quickly than reactions that require thought processes
Reflexes
Reflex action withdraws affected part before you are aware of pain. Many reflexes mediated in spinal cord without going or higher brain centers.
Withdrawal reflex
Consist of nerves that branch from the brain and spinal cord. Form the communication network between the CNS, organs and the body. Further subdivided into Somatic and Autonomic nervous systems.
Peripheral Nervous System (PNS)
Consists of nerves that go to the skin and muscles. Involved in conscious (voluntary) activities
Somatic nervous system
Consist of nerves that connect the CNS to visceral organs (e.g. heart, stomach, intestines). Mediates unconscious (involuntary) activities
Autonomic nervous system
Connective tissue sheath that surrounds a nerve. Portions of this project inward to divide the nerve into compartments. Each contains a bundle of nerve fibers.
Epineurium
A bundle of nerve fibers
Fasciculus
Connective tissue that surrounds a fasciculus
Perineurium
Connective tissue that surrounds a nerve fiber
Endoneurium
Emerge from inferior surface of the brain.
How many cranial nerves are there?
Cranial nerves (12 pairs)
Groups of nerve cell bodies located outside the brain. When sensory fibers are present in a cranial nerve cell bodies of those neurons are located here.
Ganglia
What are the 12 Cranial Nerves?
I. Olfactory
II. Optic
III. Oculomotor
IV. Trochlear
V. Trigeminal
VI. Abducens
VII. Facial
VIII. Vestibular
IX. Glossopharyngeal
X. Vagus
XI. Accessory
XII. Hypoglossal
Emerge laterally from spinal cord.
How many pairs of spinal nerves are there?
Each pair of nerves corresponds to a segment of the cord.. What are they?
31
- 8 cervical nerves (C1-C8)
- 12 thoracic nerves (T1-T12)
- 5 lumbar nerves (L1-L5)
- 5 sacral nerves (S1-S5)
- 1 coccygeal nerve (Co)
The autonomic nervous system has two neurons between the CNS and the visceral effector. What are they?
What is this neuron…
- Cell body located in the brain or spinal cord. Has an axon that is PREganglionic (shorter) fiber that leaves the CNS and synapses with a second neuron.
What is this neuron…
- Cell body is located in an autonomic ganglion. Has an axon that is POSTganglionic fiber that leaves the ganglion and goes to the effector organ.
First and second neuron
- First neuron
- Second neuron
Involved with “fight or flight” reaction. Stimulates responses that are necessary to meet an emergency. Inhibits the visceral activities that an be delayed momentarily. Increases breathing rate, heart rate, blood flow to skeletal muscle while decreasing activity in digestive tract.
Sympathetic Division System
Maintains normal function. Most active under ordinary, relaxed conditions. Brings the body’s systems back to a normal state after an emergency. Slows heart rate and breathing rate; decreases bp; decreases blood flow to skeletal muscles; increases digestive tract activity.
Parasympathetic Division
Nerve cells are lost as a person ages. Loss of neurons is largely responsible for the decrease in what?
Decline in intelligence with aging is thought to be associated with the loss of neurons. Decrease in memory; rate of impulse conduction along an axon and across a what?
- brain mass
- synapse
