A&PI Ch. 13,14,&15 Central and Automatic Nervous Systems Flashcards
What are the Main Functions of the CNS
-receiving and processing EXTERNAL SENSORY information
-integrating information from a wide range of sources: processing it, acting in it, or storing it in memory
-sending signals that control the main functions of body tissues
-consciousness perception of senses, language, reason, memory, emotion, etc.
What are the two main cell types in nervous tissue?
Neurons and Glial Cells
What is a nerve?
-a bundle of axons outside the brain and spinal cord
- two kinds (cranial and spinal nerves)
Cranial Nerves
originate from the brain; 12 pairs
Spinal Nerves
originate from the spinal cord; 31 pairs
Ganglion
collection of neuron cell bodies outside the brain and spinal cord
Plexus
extensive network of axons, and sometimes neuron cell bodies, located outside CNS
Glial Cells
supportive cells with many functions
5 Important Facts about the CNS
1) The CNS consists of the brain and spinal cord
2) Only 10% of CNS cells are neurons; the rest are neuroglia
3) The CNS is supported by the cerebral spinal fluid (CSF)
4) THE CNS is protected by meninges, CSF, and the BBB
5) White matter is inside the brain, outside the spinal cord
What is the brain protected by?
- Bones of the skull
- Meninges
- (CSF) Cerebral Spinal Fluid (liquid cushion)
- Blood-brain Barrier (controls what passes from the blood to the brain)
Meninges Dura Mater
- superior layer of meninges (under bone layer)
- thick, strong connective tissue layer
Meninges Arachnoid Mater
- 2nd layer of meninges
- thin, transparent fibrous membrane
Meninges Pita Mater
- 3rd layer of meninges
- delicate connective tissue layer
Functions of CSF
-homeostatic regulation of ions and nutrients in extra cellular environment
-support and cushioning of the brain and spinal cord with buoyant forces
-chemical and immunological buffering of the fluid surrounding neurons and glia
CSF Moves through the brain through __________.
Ventricles
Ventricles
-store CSF and provide a continuous flow of CSF between brain and spinal cord
CSF is produced by specialized tissue (_______ _______) and _________ ______ within ventricles.
choroid plexus; ependymal cells
Functions of BBB
-regulates which substances enter the brain’s interstitial fluid
-helps prevent neuron exposure to harmful substances via tight junctions of endothelial cells
-some molecules can pass (alcohol, cocaine, and small bacteria)
-The BBB is reduced in certain regions of the CNS for functional regions- areas of high hormones secretion like hypothalamus
Which arteries are in the Circle of Willis?
Internal Carotid Artery and Vertebral Artery
Internal Carotid Artery
- Portion of the Circle of Willis
- Anterior portion of the brain
Vertebral Artery
- Portion of the Circle of Willis
- Posterior portion of the brain
True or False? There is only one pathway of blood flow in the brain.
FALSE There are multiple paths of blood flow (in case one gets blocked)
True or False? The Circle of Willis allows blood supplying anterior and posterior portions of the brain to overlap
True because there are multiple paths of blood flow, the Circle of Willis allows an overlap to pick up the slack of the other side possibly (safeguards the CNS to maintain blood flow)
Anterior Communicating Artery
- connects both anterior cerebral arteries
- safeguard the CNS to maintain blood flow
Function of the Formation of the Basilar Artery from the two vertebral arteries and spinal arteries
safeguard the CNS to maintain blood flow
What is a stroke?
- Interrupted blood flow to the brain has caused neuronal death (Circle of Willis gets interrupted)
- there are two types (Ischemic and Hemorrhagic)
Ischemic Stroke
-reduced blood flow (blood clot or embolism)
Hemorrhagic Stroke
- bleeding (bleeding out, aneurism)
Risk Factor of a Stroke
Hypertension (elevated blood pressure), smoking, obesity, elevated blood cholesterol, diabetes, or heart problems
What are the 3 Types of Neurons?
- Sensory/ Afferent
- Motor/ Efferent
- Interneurons/ Association Neurons
Sensory/ Afferent Neurons
action potential travels toward the CNS
Motor/ Efferent Neurons
action potential travels away from the CNS (E= exit)
Interneurons/ Association Neurons
within CNS from one neuron to another (relay)
What are the 4 different structural classifications of Neurons?
- Multipolar
- Bipolar
- Pseudo- unipolar
- Anaxonic
Multipolar
-most neurons in CNS; motor neurons
-has many dendrites and an axon
Bipolar
-sensory in the retina of the eye and nose
-has a dendrite and an axon
Pseudo- Unipolar
-SINGLE process that divides into two branches. Part that extends to the periphery has dendrite-like sensory receptors
-appears to have an axon and no dendrites
Anaxonic
-no axons, only dendrites; found in the brain and retina where they only communicate using graded potentials
-has multiple branches but no axons
______ makes up 90% of the cells of the CNS
Neuroglia Cells
Types of Neuroglia Cells/ Glial Cells of the CNS
-Oligodendrocytes
-Astrocytes
-Ependymal Cells
-Microglia (resident macrophages)
Oligodendrocytes
-type of neuroglia cell/ glial cell of the CNS
-creates myelin sheath surrounding neurons (schwann cells in lab)
-touches multiple neurons
Astrocytes
-type of neuroglia cell/ glial cell of the CNS
-multiple functions including neurotransmitter secretion/ absorption
-3D structure of the brain
-glycogenesis
-fluid regulation
-release of ATP
-repair
Ependymal Cell
-type of neuroglia cell/ glial cell of the CNS
-secretes CSF
CSF
Cerebral Spinal Fluid
Microglia
-type of neuroglia cell/ glial cell of the CNS
-resident macrophages
-removes damaged neurons
-recognizes infectious agents
-prevents inflammation
-can cause tuberculosis to enter the BBB
What are the functions of Astrocytes in the CNS?
-Processes that form feet that cover the surfaces of neurons and blood vessels and the pia matter.
-Regulate what substances reach the CNS from the blood (BBB) lots of microfilaments for support.
-Produce chemicals that promote tight junctions to form the BBB.
-Regulate extracellular brain fluid composition.
What are the functions of Ependymal Cells in the CNS?
-Line the brain ventricles and spinal cord central canal. Specialized versions of ependymal form choroid plexuses.
-Choroid Plexus within certain regions of ventricles. Secrete cerebrospinal fluid. Cilia help move fluid through the cavities of the brain. Have long processes on basal surfaces that extend within the brain tissue, may have astrocyte-like functions.
What are the functions of Microglia in the CNS?
-resident macrophages
-respond to inflammation
-phagocytize necrotic tissue, microorganisms, and foreign substances that invade the CNS
What are the functions of Oligodendrocytes in the CNS?
-Form myelin sheaths if surrounding axon.
-Single oligodendrocytes can form myelin sheaths around portions of several axons
Which neuroglia cell type secretes CSF?
Ependymal Cells
Convergent Pathways
-neuronal pathway
-many converge and synapse with a smaller number of neurons
-ex. synthesis of data in the brain
Divergent Pathways
-neuronal pathway
-small number of presynaptic neurons
-synapse with a large number of of postsynaptic neurons
-ex. important information can be transmitted to many parts of the brain
Reverberating Circuit
-neuronal circuit
-outputs cause reciprocal activation
-ex. rhythmic activities such as breathing
Parallel After-Discharge Circuit
-neuronal circuit
-neurons stimulate several neurons in parallel organization, which converge upon a common output cell
-ex. complex data processing in the brain
Simple patterns of neuronal circuits
1 to 1 ratio but not always simple thoughts
Complex patterns of neuronal circuits
signals back to original neuron
Divergent patterns of neuronal circuits
one neuron to multiple neurons
Convergent patterns of neuronal circuits
multiple neurons to one neuron
Rhythm patterns of neuronal circuits
-cyclical (never stops)
-ex. breathing
-abnormalities are related to seizures
Parrallel after Discharge of neuronal circuits
-one neuron relays signal to many neurons then converges into a few neurons (difficult math)
True or False? Synaptic Connections between neurons can be built and maintained when used during adulthood
True
A ______ ____ is the smallest, simplest neuronal circuit.
Reflex Arc
Basic Components of a Reflex Arc
- sensory neuron
- motor neuron
- target tissue
Reflex Arc
- can be monosynaptic or polysynaptic
- can be afferent or efferent
Afferent
dorsal, sensory
Efferent
ventral, motor
Four Major brain regions
- Cerebrum
- Diencephalon (middle or inside)
- Brainstem
- Cerebellum
Gyri
elevated ridges or hills (noodles)
Sulci
small grooves or valleys (depressions)
Fissures
deep grooves or canyons (deeper than sulci)